PLASMA TRAINING PROGRAM

PLASMA TRAINING PROGRAM
等离子技术讲座: 等离子原理及其应用 PLASMA TRAINING PROGRAM

目录 Agenda March公司产品介绍等离子技术在高级封装工业的应用
Application of Plasma Technology in Advanced Packaging Industries. 等离子技术简介 Introduction to Plasma Technology March公司产品介绍 Products of March Plasma Systems This presentation includes four parts: 1. Overview of advanced packaging industries 2. Application of Plasma technology 3. Introduction of plasma technology 4. Products of March Plasma Systems

in Advanced Packaging Industries
等离子技术在高级封装工业的应用 Plasma Application in Advanced Packaging Industries Because the cleaned surface is desired for the reliability and quality of the microelectronic package, how to clean the surface becomes a key issue to reach the success in advanced packaging industries. In this part, the plasma application will be introduced.

综述 Overview: 微电子工业 Microelectronic Industry
Flash, EEPROM DRAM, SRAM Analog/Linear Microcontrollers, Microprocessors, Microperipherals ASIC 光电子工业 Optoelectronic Industry Laser Diodes Fiber Assembly Hermetic Packaging MEMS 印刷电路工业 Printed Circuit Industry Printed Circuit Board Flash - a programmable memory chip derived from EEPROM technology that can be erased in a flash and holds its content without power EEPROM - Electrically Erasable Programmable Read Only Memory, programmable chip that holds its content without power. DRAM - Dynamic Random Access Memory, primary memory for computers. SRAM - Static Random Access Memory, requires power to hold its content, this type of memory has much faster access times than DRAM. Analog/Linear - Convert conditions such as temperature and sound into electrical signals Microcontrollers - a single chip that contains the processor, RAM, ROM, clock and I/O control unit. ASIC - Application Specific Integrated Circuit, custom semiconductors for very specific functions such as in camcorders, airbag systems and printers

集成电路封装面临的挑战 IC Assembly and Packaging: Specific Challenges
不良的芯片粘结 Poor Die Attach Insufficient Heat Dissipation Due to Poor Die Attach 不良的导线连接强度 Poor Wire Bond Strength Contamination on Bond Pad 覆晶填料 Flip Chip Underfill Fillet Height of Underfill Void in Flip Chip Underfill 剥离 Delamination Laminate Materials Releasing Moisture Metal Leadframe Oxidation 印刷电路板孔中的残余物 Smearing in Printed Circuit Boards 打印记号 Marking Clean surface vital for good adhesion of thin film coatings or of soft solder on metallic substrates. Surfaces must be free of contamination prior to any kind of attach process for mechanically stable, electrically and thermally well conducting connections. Superficial contamination includes: Humidity, Hydrocarbon, Oxygen, Sulfur, Chlorine, Phosphorus Contaminated surface can influence the adhesion process in many ways. Contamination may reduce the surface tension and hinder or prevent wetting with liquid solder in the case of die bonding. They may lead to delamination of the mold material and to package cracking (popcorn effect) during reflow processes. And they can lead to high wire bond and corrosion failure rates in the wire bonding. Challenge is that the interface between mold compound and solder resist frequently show poor adhesion resulting in package delamination.

等离子体应用 Plasma Applications
表面污染物去除 Contamination Removal Wire Bonding Encapsulation Ball Attach (Contamination Sources: Fluorine, Nickel Hydroxide, Photoresist, Epoxy Paste, Organic Solvent Residue, smear in PCB, and scum) 表面活化 Surface Activation Die Attach Flip Chip Underfill Marking 表面改性和刻蚀 Surface Modification and Etch Fluxless Soldering Cladding layer removal on fiber Applications of plasma technology include: 1.) Contamination Removal - all forms of contamination can compromise adhesion in the integrated circuit manufacturing process. Sources of contamination include: chemicals used in the integrated circuit wafer manufacturing process; outgassing from the package substrate materials or from the adhesive materials; airborne contamination; or human skin contact. Processes which are impacted by contamination include: Encapsulation, Wire Bonding, and Ball Attach. 2.) Surface Activation - Increasing the surface energy of a material will allow for improved adhesion in Encapsulation, Die Attach, Flip Chip Underfill, and Marking processes. 3.) Process Enhancements - Plasma treatment of the solder can produce a fluorine containing layer which when reheated will act as a flux material in the soldering process. The cladding layer removal on fiber can also be realized by plasma process

表面活化: 芯片粘结 Surface Activation: Die Attach
Proper Die Attach Critical Heat Dissipation Delamination Plasma Treatment of Substrate Prior to Die Attach Promotes Adhesion of Epoxy Removes Oxidation For Good Solder Reflow Better Bond Between Die and Substrate Better Heat Dissipation Minimizes Delamination Adhesion of the epoxy to the die and substrate is critical for good heat dissipation and prevents delamination of the die Plasma cleaning of substrates improves adhesion of the epoxy and provides a better bond between the die and the substrate. Better bond means better heat dissipation. Also less delamination of the die after treatment. – Plasma cleaning of substrates improves adhesion of the epoxy and provides a better bond between the die and the substrate. Better bond means better heat dissipation. Also less delamination of the die after treatment. Die attachment to lead frame or cleaning lead frame to get good adhesion of the molding process which could decrease delamination. Plasma cleaning of substrates will improve the adhesion of the epoxy and provide a better bond between the die and the substrate – better bond provides improved heat dissipation.

污染物去除: 导线连接 Contamination Removal: Wire Bonding
Poor Wire Bond Strength Contamination Oxidation Smaller Bond Pad Pitches 80 mm to 25 mm Higher Ratio of Contamination to Pad and Wire Deformation Welding Inhibited By Physical Process: Contaminants Act As Physical Barrier Chemical Process: Contaminants Form Bonds With Surfaces and Minimize Adhesion Epoxy Resin Bleedout Due to smaller devices, bond pad pitches are decreasing from 80 micron down to 45 micron and roadmaps indicate further reduction with expectations of microns – to ensure high device reliability, must optimize wire bonding process. Poor bond strength and low bonding yields are often a result of contamination or oxidation on the bonding pad. Smaller bond pad – higher ratio of contamination to the pad and wire. The epoxy used for die attach has organic solvents and volatile components that can migrate to the bonding pads and prevent good adhesion in the wire bonding process. Small amounts of contamination on surfaces to be welded can inhibit bonding by physical and chemical mechanisms. In deformation welding, the forces act over only a few molecular layers so contamination can be critical. Physical – contaminants act as a physical barrier acting as a spacer between the land and the wire, preventing contact. Chemical – interference can be caused by contaminants forming bonds with metallic surfaces and thus decreasing adhesion by limiting the number of available bonding sites. In BGA type packages, the BGA polymer substrates are prone to outgassing during die cure step and the resulting contamination often deposits on the bond pads. Epoxy Bleedout Removal – when epoxy is applied to microcircuit surfaces, a small amount of resin separates from the epoxy, and the resin enters small crevices on the gold surfaces and spreads out to the surrounding area. The bleeds can be as from 10 to 2500 angstroms thick and 50 mils from the epoxy. The bleeds can occur on the bond surface resulting in low quality bonds or failures. After the epoxy has been cured it is very difficult to observe the bleedout

污染物去除: 导线连接 Contamination Removal: Wire Bonding
Plasma Processing Removes Trace Contamination and Oxidation From Substrates Metal Ceramic Plastic Wire Bond Strength Significantly Increased Throughput Increased: Lower Pressure Required A cleaner surface for wire bonding also has the added benefit of increasing the wire bonder’s performance. Studies have demonstrated that plasma treated substrates require lower required pressure in the bonding step. The lower pressure results in a decrease in process time, and thus an increase in throughput.

污染物去除和表面活化: 封装 Contamination Removal and Surface Activation: Encapsulation
Molding Compound Must Adhere To Different Compounds Substrate Material Solder Mask Die Metal Bond Pads Several Materials Bonding to One Another Delamination Can Result From Poor Surface Activity and Contamination Encapsulation - molding compound must adhere to a number of different surfaces including substrate material, solder mask, die, and the metal bond pads. This requires several materials bonding to one another.

污染物去除和表面活化: 封装 Contamination Removal and Surface Activation: Encapsulation
Delamination Biggest Challenge For Organic Based Substrates Laminate Materials Absorb Water From Air and the Flux Residue Removal Process Trapped Moisture Released From High Temperatures: Use or Soldering Oxidation on Metal Leadframes Can Inhibit Adhesion of Frame to Mold Plasma Treatment of BGA Packages, Other Polymer Substrates, and Metal Leadframes Improves Surface Activity Achieves Good Adhesion Minimizes Delamination Delamination is the biggest challenge for organic based substrate because of outgassing and moisture release during the process. Oxidation on metal leadframes can inhibit the adhesion of frame to mold. The plasma process can remove the contaminants and oxide from the surface and activate the surface, thus, minimize the interface delamination.

表面活化: 填料 Surface Activation: Underfill
Underfill Required in Flip Chip Minimize Thermal Coefficient of Expansion (CTE) Mismatch Between Die and Substrate Challenge Void Free Wicking Speed Difficult with Large Dies and High Density Ball Placement Plasma Treatment Increases Surface Energy Promotes Adhesion Increasing Wicking Speeds Decreased Voiding Void Free Underfill - Unique challenge in Flip Chip packaging is the underfill process, particularly designs that utilize large dies, tight gaps, and high density ball placement. Flip Chip Underfill – In this packaging process it is extremely important for the epoxy underfill to wick under the chip without voiding in a timely manner. Plasma treatment increases surface energy promoting adhesion, minimizing voiding, and increasing wicking speeds. Proper application of plasma cleaning, after die attach and prior to the application of the underfill epoxy will compel the epoxy to wick quickly under the chip and greatly improve the homogeneity of the under-fill material. Two key benefits of plasma treatment: decreased voiding and increased dispensing speeds.

氧化物去除 Oxides Removal Presence of Oxides
Inhibits Wire Bonding Limits Good Die Attachment Inhibits Solder Reflow Plasma Treatment Reduces Metal Oxides Improves Wire Bond Strength Improves Die Attachment Improves Solder Reflow Oxidation - Presence of oxides inhibits wire bonding and solder reflow. Eutectic solder is used as an adhesive material for die bonding – oxidation can limit good die attachment. Plasma treatment reduces metal oxides and improves wire bonding and solder reflow. Eutectic solder is used as an adhesive material for die bonding – oxidation can limit good die attachment. –Reduce Metal Oxides to improve soldering

印刷线路板上的残余物清除 Desmearing in PCB
Smearing in Printed Circuit Boards (PCB) Vias Mechanically or Laser Drilled Laminate Material (Epoxy Resin) Is Smeared Over Edges Of Inner Metal Conductor Lines Subsequent Plating Of The Vias Must Electrically Connect All The Conductor Lines Smeared Resin Must Be Removed To Ensure Good Electrical Contact Plasma Treatment Removes the Epoxy Resins Producing Carbon Dioxide and Water Desmearing in Printed Circuit boards – when vias are mechanically or laser drilled in printed circuit boards (PCB) some of the laminate material (usually epoxy resin) is smeared over the exposed edges of the inner metal conductor lines. Subsequent plating of the vias must electrically connect all the conductor lines intersected by the via on the different layers. The smeared resin must be removed to ensure good electrical contact. Desmearing normally uses oxygen and carbon tetrafluoride – the process is the reaction of the epoxy resins to produce carbon dioxide, water, and hydrogen fluoride

集成电路封装中等离子工艺的应用 IC Assembly and Packaging: Plasma Solutions
Improves Die Attach Improved Wire Bond Strength With Minimal Process Requirements Effective Encapsulation of Metal and Organic Based Packages Minimizes Voids in Flip Chip Underfill Desmearing in Printed Circuit Boards This is the summarization of the plasma application 1. Improve the die attach 2. Increase the wire bonding strength with minimal process requirement 3. Effective for the organic based packaging 4. Minimize the void in flip chip underfill 5. Effective to desmear

等离子工艺的其它应用 Other Plasma Applications
Surface Activation of Numerous Materials: Polymers, and Metals 材料表面的活化 Thin Film Etch: Al, Si, SiO2, Si3N4, W, WSix Organic Removal去除有机污染物 Oxide Removal去除氧化物 Residual Fluorine Removal去除氟的残物 Hydrophilation Hydrophobation Plasma polymerization PECVD The other application of plasma process includes: 1. surface activation of different materials 2. Thin film etching 3. Surface cleaning, remove organic, fluorine, and oxide material from the surface. 4. Surface hydrophobition and surface hydrophiliation. 5. Thinfilm deposition, plasma polymerization and PECVD.

关键参数 Critical Product Parameters
Product Type 处理方式 Metal vs. Laminate Chemical Sensitivity Temperature Sensitivity Product Handling 产品放置 Magazine Single Strip Process Required 工艺的要求 Contamination Removal Surface Activation Throughput 产量的要求 Uniformity 均匀性要求

等离子工艺参数 Parameters For Plasma Processing
Power Supply Frequency and Power 电源的功率和频率 Chamber and Electrode Configuration 腔体的结构 Pressure气压 Gas and Concentration工艺气体的选择 Time处理的时间 Pumping Speed 真空泵的速度 Product Positioning产品的位置 Parameters Function of Product Type

March 单一工艺不适合所有的应用等离子技术及集成电路封装工艺的知识是成功应用的关键 MARCH拥有等离子应用的专家解决你的问题
Single Process Will Not Work For All Applications 等离子技术及集成电路封装工艺的知识是成功应用的关键 Knowledge Of IC Package and Plasma Technology Critical For Successful Application MARCH拥有等离子应用的专家解决你的问题 March Maintains Experts Trained In Plasma Technology To Solve Your Problem

等离子技术 Plasma Technology www.nordsonplasma.com
In plasma processing electrical energy is substituted for heat. Plasma electrons transfer the externally applied electrical energy to the gas. The electrons are accelerated in the electrical field and collide with gas molecules as they move throughout the region influenced by the field. The electrons are much less massive than the atoms and thus are influenced more strongly by the electrical field than the atoms. The electrons continue to gain energy from the applied field until the energy is sufficient (a few electron volts) that a collision with a atom or molecule will cause the atom or molecule to rotate, vibrate, dissociate, or become ionized as a result of the collision. The impact ionization process will produce an additional electron, the original electron and the additional electron can now be influenced by the electrical field causing an electron multiplication effect. A highly reactive environment is created in a plasma at relatively low temperature ( C).

等离子体简述 Plasma: What, Why, How
Gas Phase Mixture Consists of: Neutral, Physically Active and Chemically Reactive Species 如何工作 How? By Physical Bombardment and Chemical Reaction to Remove Contamination Activate Surface Etch 为什么要用等离子体技术 Why? Improves Yields and Enhances Reliability of IC Packages Improves Adhesion of Wire Bonds, Die Attach, and Molding Ease of Use, Environmentally Benign, Low CoO Plasma is a partial ionized gas, which contains ions, electrons, free radicals, photos, matastable state and neutral state molecules (or atoms). It is neutral state but electrical conductive gas. Since many activated species existed in plasma, The activated species can physically bombard the surface or chemically react the molecules on the surface, resulting in the surface has been modified. This process can be surface cleaning (if contaminants has been removed by plasma), etching (if thin film has been removed), activation (if the new function group forms on the surface), or deposition (if the thin film forms on the surface). The reason the plasma is chosen is that the plasma process improves the yield and enhances reliability of IC package. Improves the adhesion of wire bonding, die attach, and encapsulation. Also it is environmentally benign process and low CoO. The plasma application can be: 1. Contamination remove 2. Surface activation 3. Descum, desmear, and etch.

什么是等离子体 What is a Plasma?
Fourth State of Matter Plasmas are often considered the fourth state of matter. The number density of particles in solids, liquids, and gases are too dense for classical plasmas to exist. Typical examples of plasmas are flames, neon signs, and fluorescent lamps.

什么是等离子体 What is a Plasma?
固态  液态  气态  等离子态 Solid  Liquid  Gas  Plasma Energy Energy Energy Solid - Fixed volume and shape. In a molecular solid the individual particles vibrate about fixed lattice positions but are not free to move about. Liquid - Fixed volume but assumes the shape of the container into which it is poured. A molecular view of a liquid is that the particles are in continuous contact with each other but are free to move about throughout the liquid. Gas - neither a fixed volume or shape, it always expands to occupy the entire volume of any closed container into which it is placed. Plasma - Similar characteristics of a gas except that the plasma can conduct electricity.

等离子体的组成 Components of a Plasma
电子 Electrons 离子 Ions Positive Ar + e Ar e- Negative Cl e Cl- 自由基 Free Radicals: CH4 + e CH H + e- 光子 Photons Ar + e Ar* + e Ar + e- + hn 中性粒子 Neutrals Electrons Free electrons initiate the ionization process in a plasma. Exposure of the free electrons to an external energy source allows the electrons to gain sufficient kinetic energy such that a collision with another atom or molecule will result in the formation of ions, and free radicals. Ions Positive Ions – collision of electron results in the removal of an electron from that atom or molecule. An atom or molecule which has lost one or more electrons is a positive ion. Positive ions are important in physical cleaning mechanisms in surface treatment by bombardment of the surface with positive ions. Negative Ions – collision of electron results in the addition of the electron to the atom or molecule. Atom or molecule that gains the electron is a negative ion Free Radicals – collision of electron can dissociate a molecule into neutral species atomic and molecular species or into atomic or molecular species that have a lone electron. Free radicals are extremely reactive and the most reactive species within the plasma. Photons – the ions and free radicals formed in the plasma are not stable due to their higher energy state – these species can lose this energy by collisions with other electrons, atoms, or molecules to produce neutral gas species or they can release the energy in the form of a photon. The energy release is in the form of ultraviolet light. These UV photons are useful for the surface treatment of plastic materials. The UV light is more energetic than the visible light observed in a plasma and is of sufficient energy to break chemical bonds

等离子体特性 Plasma Properties
高能量态 High Energy State Physical Work Chemical Work 电中性的 Electrically Neutral Equal Numbers Of Positive and Negative Species Degree of Dissociation = % Electrically Conductive A Plasma is a high energy state capable of doing both chemical and physical work. Physical work is in the form of sputtering, and chemical work is in the form of chemical reactions. A plasma is electrically neutral, thus having equal numbers of positive and negative charges. The plasma does however conduct electricity. Species Present in Discharge – in general for every 106 reactive gas molecules, 104 will form free radicals and only one will ionize.

表面反应机理: 物理反应 Surface Reaction Mechanisms: Physical
Sputtering - Argon Plasma Substrate Placed on (-) Electrode Ar+ Ion Attracted to (-) Electrode Impact Force Removes Contamination Advantages Non-Chemical Reaction: No Oxidation Pure Substrate Remaining Disadvantages - Easy to Minimize Substrate Damage: Impact, and Overheating Poor Selectivity Low Etch Rate Contaminant Redeposition Surface Reaction Mechanisms – Physical vs. Chemical character can be manipulated by changing the power and pressure. For high power and lower pressure more physical processes (the goal is to get maximum acceleration of the argon ions before they hit the sample surface, high power is needed because the more energetic the plasma, the greater the average velocity of the atoms and ions in the plasma, the low pressure is to maximize the mean free path), for lower power and high pressure more chemical. The Process of cleaning relies on the reactive species getting to the surface, either reacting or imparting enough force to remove the contaminant. If the reaction is not thermodynamically favorable then additional energy must be provided. Physical Mechanism –sputtering, high anisotropy, low selectivity, low etch rate. Very few radicals formed in argon plasma, the plasma ions bombard the surface, desorb the contaminant, the contaminant can be pumped out or it reacts with the plasma to form a more volatile byproduct which is pumped out the system. The large mass of the argon atom is capable of imparting a lot of force.

表面反应机理: 化学反应 Surface Reaction Mechanisms: Chemical
Plasma Generated Reactive Chemical Species Source Chemicals Include: H2, O2 and CF4 Ionized Source Chemical Produces Reactive Species Gas Phase Products Produced From Reactions with Substrate Surface Advantages High Cleaning Speed High Selectivity Effective for Organic Contaminants Disadvantages - Oxides Can Be Produced Chemical Mechanism – low anisotropy, high selectivity, high etch rate, new volatile compounds are created from a chemical a reaction of the radical species produced in the gas phase with those on the material surface. The products from the chemical reaction are volatile and can be removed from the vacuum system with the vacuum pump.

表面反应总结 Summary of Surface Reaction Mechanisms
Physical Cleaning High Anisotropy = Highly directional plasma Low Selectivity = The physical process of sputtering will be specific for a chemical contamination, but will sputter the surface uniformly Low Uniformity Low Cleaning Rate Chemical Cleaning Low Anisotropy = Typically purely chemical process are performed at high pressures and thus result in very isotropic cleaning. High Selectivity = Selection of the plasma source gas can dramatically impact the selectivity of the chemical cleaning. It is possible to clean silicon dioxide in the presence of silicon. High Uniformity Faster Cleaning Rate

等离子技术的优点 Advantages of Plasma Treatment
Very Effective for Surface Cleaning, Activation, and Etching Environmentally Friendly - Low Gas Flow Non-Hazardous 非危险 No Aqueous Chemicals Used No Personnel Exposure to Chemicals Three Dimensional Treatment Capability(3D处理) Controllable Low Cost Of Ownership Minimal Maintenance Ease of Use - Automated High Uniformity and Reproducibility It is the summary of the advantages of plasma process.

等离子工艺 Plasma Process 气相---固相表面相互作用分子级污染物去除
Gas Phase - Solid Phase Interaction Physical and Chemical 分子级污染物去除 Molecular Level Removal of Contaminants 30 to 300 Angstroms 可去除污染物包括 Contaminants Removed 难去除污染物包括 Difficult Contaminants Finger Prints Flux Gross Contaminants Oxides Epoxy Solder Mask Organic Residue Photoresist Metal Salts (Nickel Hydroxide) Generally, the inorganic materials are difficult removed by plasma process unless it is very thin (few molecules levels). Organic contaminants can be removed by plasma process unless it is gross contaminants.

等离子体的产生 Generating a Plasma
four components are required to generate a plasma. These are vacuum chamber, gas source, power source and vacuum pump.

Gas To Be Ionized Chamber With Electrodes Materials Aluminum Stainless Steel Glass: Quartz, Pyrex Configuration Barrel Cylindrical Usually Glass External Electrodes Parallel Plate Box Internal Electrodes: Powered, Grounded, or Floating Custom Barrel – electrodes are external to a cylindrical chamber usually made of glass or quartz (can be metal). Not designed for optimum uniformity and thus the cleaning/etching is not uniform Parallel Plate – Typically a box type chamber with a capacitively coupled internal electrodes (electrodes can be powered, grounded or floating). Produces high uniform cleaning results with a large chamber capacity. Chamber is typically stainless steel or aluminum. Insulators are ceramic (sometimes Teflon is used but it can be a source of contamination).

Vacuum Pump MilliTorr Process Requirements (50mTorr mTorr) Rapidly Remove Byproducts Rotary Vane Pump Roots Blower Power Supply Energy Source Various Frequencies 2.45 GHz 13.56 MHz 40 kHz DC Various Powers Vacuum Pump – Standard technologies require reduced pressure. Atmospheric plasmas are possible but typically require high voltage and low frequency. The limitation is power and mean free path. The pump must have the ability to rapidly remove the byproducts. Cleaning applications requires a soft vacuum (50 mTorr to 1 Torr).

等离子体的重要特性 Important Properties of a Plasma
等离子工艺优化 Effective Plasma Processing Requires Optimum: Physical Processes Chemical Processes 等离子工艺参数 Plasma Properties That Dictate Process Performance: Ion Density Ion Energy DC Bias Th process parameters need to be optimized for successful plasma processing. It includes the physical process and chemical process. The important parameters to determine the plasma process performance are ion density, ion energy and DC bias.

等离子体的电子和离子特性 Plasma Electron and Ion Properties
离子密度 Ion Density Number of Ions per Unit Volume Typically 1 Ion per 10,000 Neutrals 100 Radicals per 10,000 Neutrals Higher Ion Density = Higher Number of Reactive Species High Number of Active Species = Increased Speed, and Uniformity Requires Efficient Coupling of Power Ion Density = Defines the number of ions in the plasma region. Higher ion densities equates to higher number of ions in the plasma, thus greater number of reactives which yields an increase in efficiency uniformity, and speed of the cleaning process. Uniform ion density requires efficient coupling of power to the process chamber and adequate reionization energy within the process chamber. Low ion density will require an increase in process time. In general, the higher the frequency of power, this higher the ion density. Ion Energy = Plasma is electrically neutral having equal numbers of positive and negative ions. Sputtering is an example of an application where we need good ion energy to break the bonds from a physical collision. (For example – the die can have residual fluorine on the aluminum bond pads, this fluorine can be detrimental to the reliability of the gold wire bonds.) Challenge is that excess energy can result in unwanted sputtering of the bond pad site which can lead to deposition of the bond pad material onto other parts of the die or package which can result in short circuiting.

离子能量 Ion Energy Energy of Ion To Do Work = Sputtering Sputtering Charged Species Collides With Surface Energy Sufficient To Break Bonds Surface Material Released Narrow Range Excess Ion Energy = Unwanted Sputtering Too Low Ion Energy = No Sputtering or Slow Process

直流偏压 Self DC Bias Negative DC Bias At Power Electrode Capacitively Coupled Electrons Respond to Alternating Electrical Field Capacitor Prevents Electron Flow At Power Electrode Electrons At Ground Electrode Flow To Ground Potential Electron Build Up At Electrode Causes Potential Difference Between Powered and Ground Electrodes = Self DC Bias DC Bias Increases Ion Energy Directionality of Ions Important Parameters: Pressure, Power, Process Gas DC Bias = negative bias at powered electrode. Changing the process pressure, power, and process gas choice can control the DC bias. The DC Bias is important in applications requiring directionality such as treating magazines, ion bombardment, such as fluorine contamination removal, flip chip underfill improvement, and processes requiring faster etch rates. Self Bias – Two ways to couple AC power into a system Inductive – yields higher ion density, but no Self DC Bias Capacitive – lower ion density, but self DC Bias. Self Bias is a function of pressure, power, type of gas and electrode geometry. Electrons due to their size (unlike the large ions) respond rapidly to the alternating RF potentials, moving back and forth between the electrodes. Some of the electrons touch the electrodes – those that touch the powered electrodes stay at the electrode due to a capacitor which prevents the electron flow consequently producing a negative potential on the powered electrode. The electrons which reach the ground electrode flow to ground and produce zero potential. The difference in the potential between the two electrodes is the self bias. This self bias is a negative DC potential between the powered and the ground electrodes. This DC bias increases the ion energy which results in more directional treatment at a faster rate.

等离子处理模型 Plasma Modes Direct Downstream (Shielded)
Sample Placed Directly In Discharge Samples Placed On Ground or Powered Electrodes: Application Dependent Aggressive Downstream (Shielded) Plasma Generated Downstream Of Samples Gas Phase Active Species Directed To Sample Ions Removed Radicals and Photons Perform Work Reactive Ion Etch (RIE) Direct and Anisotropic Samples Placed On Powered Electrode: Self Bias Direct– most aggressive, places sample between powered and ground electrode (depending upon the device type – some samples will need to be placed on the grounded electrode and some on the powered) Typically users are concerned about damage as a result of the direct plasma processing – this is a legacy from the wafer side of the industry where the wafer can be exposed to a plasma and the wafer surface has unpassivated components. In this application the devices are exposed to a gentle plasma for minutes, and the devices are passivated. If it is a concern, a downstream plasma can be used, at the cost of throughput. Downstream or Shielded - appropriate for those applications where the substrate could be damaged by exposure to the direct plasma. In this case the plasma is generated between two electrodes, and the gas stream is directed though perforations in the grounded electrode to the samples which are held on a electrically isolated (floating) shelf. Because the electrode is grounded the ions which may damage the sample are removed and only the noncharged radicals and photons can travel to the substrate surface. Note: the existence of ions could significantly increase the etch rate due to bombardment. Downstream plasma has three regions in the secondary plasma region (Afterglow region): they are the decaying plasma region (ion species decay due to diffusion and recombination), the near afterglow region (primary active species are the long lived free radicals and metastable neutrals), and the far afterglow which has no reactives. Directional Directional (RIE) – Like the Direct case except that the substrates are always placed on the power electrode to take advantage of the self bias, and thus the directional ability of the plasma

Direct Plasma: Argon (Ar)

Direct Plasma: Oxygen (O2)

Downstream: Ion-Free Plasma

等离子处理模型 Plasma Modes Reactive Ion Etch (RIE) Direct and Anisotropic
Samples Placed On Powered Electrode: Self Bias

成功应用的关键参数 Critical Parameters For Successful Application
Power Supply Frequency and Power Chamber and Electrode Configuration Pressure Gas and Concentration Time Pumping Speed Product Positioning Parameters Function of Product Type

电源功率及频率 Power Supply Frequency and Power
General Trend: Higher Frequency = Lower Ion Energy Higher Frequency = Higher Ion Density Higher Power Increases Etch Rate Increases Temperature Power Supplies DC Low Frequency (40 kHz kHz) Medium Frequency (13.56 MHz) High Frequency (2.45 GHz) Power Supply - Frequency of Power Supply and Power General trend is the higher the frequency (from kHz to GHz) the ion energy decreases, however for ion density the opposite trend holds. In general, increasing the RF power increases the cleaning rate but also increases the temperature.

为什么选择频率13.56MHz? Frequency: Why 13.56 MHz ? Ion Density Ion Energy
DC kHz MHz 2.45 GHz Power Frequency

真空腔及电极组合 Chamber and Electrode Configuration
Barrel External Electrodes Non-Uniform Plasma Parallel Plate Internal Electrodes Polarity Powered Higher Etch Rate, Higher Temperature, Lower Uniformity Ground Lower Etch Rate, Lower Temperature, Higher Uniformity Floating Electrode Configuration - Polarity Power vs. Ground Electrode – Placing the substrate on the powered electrode results in an increase in cleaning time and etch rate when compared to the ground shelf. However, the temperature of the power electrode can become hotter than the ground, and ground electrode cleaning results in more uniform cleaning at a lower temperature at the cost of a slower etch rate. The consideration of uniformity, temperature, and etch rate must be considered to determine optimum configuration.

气体及浓度 Gas and Concentration
Argon (Ar) Inert Physical Process: Surface Bombardment Ar + e Ar e- Ar+ + Contaminant Volatile Contaminant Two to Five Nanometers Removed Applications: Oxide Removal, Epoxy Bleedout Oxygen (O2) Chemical Process: Oxidation of Non-Volatile Organics O2 + e O e- O. + Organic CO2 + H2O Rate Function of Gas Concentration = High Pressure Can Oxidize Surfaces and Damage Laminates Minimize With Ar or Ar/O2 Argon – Physical processing of the surface by bombardment – in the case of bombardment, some amounts of the contaminant and the substrate surface are removed. The physical process in argon plasmas is a mild form of etching where in etch processes relatively large quantities of material is removed (1 micron), where in the cleaning processes only a few monolayers are removed (2 to 5 nanometers). For an etch process, more power and time is required or a more reactive plasma (different chemicals). The key is that once a good cleaning process is defined, there is little risk that too much material will be removed. Removal of epoxy bleed out without oxidation, oxide removal. Oxygen – Chemical processing by the oxidation of non-volatile organic compounds into gas phase (volatile) small organic compounds such as carbon dioxide and water and thus can be quickly be removed from the vacuum chamber. The rate at which the organic compounds are oxidized is a function of the oxygen concentration, thus the higher the pressure the faster the treatment rate. High pressures are in the 200 to 800 mTorr range. It is preferable to use oxygen over argon because of the rapid cleaning rate when using oxygen. The disadvantage of oxygen usage is the substrate can be discolored by the oxygen due to oxidation – this is typically the case with metallic substrates or metal components on the substrate. The oxygen can also be too aggressive with some laminates – to minimize the oxidation and damage on laminate parts argon or an argon/oxygen mix can be used.

Hydrogen (H2) Chemical Process Applications Remove Oxidation On Metals Clean Metals Without Oxidation Carbon Tetrafluoride (CF4) Normally Mixed With Oxygen Free Radicals React = CO2, H2O, and HF Higher Etch Rate = Higher Pressure Other Gases: Helium, Nitrogen, Forming Gas, Sulfur Hexafluoride Hydrogen – gas of choice for removing oxidation from metals. The hydrogen can be mixed with argon to further enhance the removal rate. The flammability of the hydrogen can be concern – however the volume of hydrogen (find out volumetric flow rate) used in the process is very little and requires the presence of oxygen and an ignition source (Flammability limits for hydrogen are between 4% and 76% by volume). A concern also is the storage of the hydrogen – a hydrogen generator can be supplied that creates hydrogen from water (find a schematic for this process). Cleaning metals without oxidation, removal of oxidation. Carbon tetrafluoride - Usually mixed with oxygen. The process is extremely aggressive and can remove many types of contaminants. Sulfur hexafluoride - Can etch tungsten Forming Gas – 90-95% Hydrogen, 5-10% Nitrogen: remove oxides Nitrogen – removal of epoxy bleed out, removal of oxides Helium – cooling agent for oxygen 97% He 3% Oxygen – removal of thin film organic contamination from easily oxidized metals, low temperature removal of organics from metals with minimal oxidation, low temperature ashing.

Gas type and concentration are critical control parameters for successful application. A hydrogen plasma is a chemical process where the reactive hydrogen atoms in the plasma react with the oxide contaminants on the surface to produce gas phase water molecules. The gas phase water molecules are removed from the system via the vacuum pump. A oxygen plasma is a chemical process where the reactive oxygen atoms in the plasma react with the carbon contaminants producing carbon monoxide and carbon dioxide. A argon plasma is a physical process where the active argon atoms bombard the surface physically removing the surface contaminant. 化学清洗工艺化学清洗工艺物理清洗工艺

气体压力 Pressure Average Force Of Gas Molecules On Chamber Wall
Chamber Pressure Gas Flow Outgassing Rate Pumping Speed In General Higher Pressures ( mTorr) = Chemical Processes Higher Pressure = Larger Concentration of Reactive Species High Concentration = Faster Etch Rates Lower Pressures ( mTorr) = Physical Processes Lower Pressure = Longer Mean Free Path Long Mean Free Path = Higher Energy Of Ions Pressure – result of the gas molecules hitting the sides of the container yielding an average force being imparted uniformly across the chamber. Chamber pressure is determined by gas flow, outgassing rate and pumping speed. Pressure is a critical parameter for both physical and chemical processes. In general, higher pressures are desired for chemical cleaning, because the higher the pressure the higher the concentration of reactive species which results in higher cleaning rates – typical pressures are 200 – 800 mTorr. For physical processes – lower pressure is required because of the need for a long mean free path which in turn means that there must be fewer species in the process chamber. The greater the number of species available for bombardment, the better the cleaning rate. Note that when cleaning parts in carriers (magazines) lower pressures are required when it is a chemical or physical process because it is more difficult for the reactive species to travel into and through the carrier and yield uniform treatment – longer mean free paths are required to accomplish good cleaning for substrates in carriers

处理时间 Processing Time Longer Process Time = More Material Removed
Balance Process Time With Power: Higher Power = Faster Etch Rate Pressure: Higher Pressure = Faster Etch Rate Gas Type and Concentration Chamber Electrode Configuration Minimize Time = Maximize Throughput

样品位置 Product Positioning
Direct Open Placement On Shelves Carrier or Magazine Require Lower Pressures For Longer Mean Free Paths Easy To Get Reactive Species Into Carrier Chemical Or Physical Process Pitch Is Critical Uniformity Challenges

在清洗盒中处理 Treatment In Magazine Typical Plasma Condition:
Low system pressure (about 100 mTorr) is required. Increase the mean free path Decrease the hot spots in chamber Pitch should be larger than 6 mm. The open slot on the side wall of magazine is required.

真空泵速度 Pumping Speed Pump Required To Maintain Vacuum
Sweep Away Plasma Byproducts Minimize Re-contamination

等离子工艺中可能的问题: 温度 Plasma Problems: Temperature
Plastic Parts are Susceptible to High Temperature Factors That Effect Temperature Substrate Material of Construction Conductive - Metal Leadframes Nonconductive - BGA Placement of Parts on Electrode Ground: Cooler Temperature, Longer Process Times Powered: Hotter Temperature, Shorter Process Times Process Power and Frequency Higher Power = Higher Temperature Lower Frequency = Higher Temperature 40 kHz >> MHz Process Gas and Gas Flow Higher Gas Flow = Lower Temperature Heat Build Up – Plastic parts can be extremely susceptible to high temperatures. temperatures can reach 125C in a manufacturing environment, to minimize heat build up RF power and process time must be minimized. Liquid cooling of ground shelves in the PX product line is possible. Factors that effect the temperature and need to be optimized to minimize temperature are: Part material of construction – conductive vs. nonconductive. Conductive parts such as metal leadframes conduct the heat more efficiently, which could pose a problem if the leadframe has a sensitive component on it. Nonconductive parts such as BGA’s are sensitive to heat due to their relative low glass transition temperature. Process Power and Frequency – in general the higher the power the higher the temperature, and the lower the frequency the higher the temperature because at low frequency the ion energy is much higher. The ions impact the substrate surface with high ion energy which manifests itself in substrate heating. Process Time – the longer the time the higher the temperature. Process Gas and Gas Flow – oxygen results in higher temperatures than argon which results in higher temperatures than hydrogen. The higher the gas flow the lower the temperature.

等离子工艺中可能的问题: 温度 Possible Problems In Plasma: Temperature
Factors That Effect Temperature Process Time Longer Process Time = Higher Temperature Chamber Temperature Typically < 1250C PX Product Line Has Optional Liquid Cooled Shelves The data represented in the graph indicates that the maximum chamber temperature is less than 1200C. For temperature sensitive parts, the PX product line can be configured with liquid cool electrode shelves.

等离子工艺中可能的问题 Possible Problem in Plasma
均匀度 Uniformity Gas Supply and Removal Should Be Uniform Chemical Processes Typically Have Higher Uniformity Longer Mean Free Path - Lower Pressures For Physical Processes Can Help 表面变色 Discoloration Heat Build Up Complex Parts Can Create Plasma Hot Spots 处理寿命 Treatment Longevity Function Of Substrate Material Humidity Outgassing of Plasticizers and Mold Release Compounds

等离子工艺中可能的问题 Possible Problems In Plasma
荷载影响 Loading Effect Materials Outgas Under Vacuum Effects Pump Down Time Base Pressure Displace Process Gases Amount of Substrate Material in Chamber Effects Process Material Quantity Can Affect Plasma Density Gas Supply Could Be Insufficient 副产品 Byproducts Overtime, CF4 Will Polymerize On Chamber Walls and Can Deposit on The Substrate Surfaces

表面接触角检测 Contact Angle Measurements (CAM)
Contact Angle Indicates Surface Energy Characterizes Interfacial Tension Solid - Liquid Drop Low Surface Energy Solid (Hydrophobic) Liquid Surface Tension > Solid Surface Energy Liquid Forms Spherical Shape High Surface Energy Solid (Hydrophilic) Liquid Surface Tension < Solid Surface Energy Liquid Forms Low Profile Flatter Droplet View Droplets Of Liquid On Surface Line Tangent To Curve Of Droplet Angle Between Tangent Line and Solid Surface Contact Angle Indicates Surface Activity – Adhesion to a substrate improves with surface energy, contact angle of a water droplet on a substrate decreases with increased surface energy. Measurement of the water droplet contact angle can be used as a test for successful plasma processes. Tests for Treatment Effectiveness – high surface activation promotes good adhesion. A method for measuring surface energy is by measuring the contact angle of a deionized water droplet (Display the equation, and the diagram of the surface with the water droplet). When the contact angle is small the surface energy is high and the surface is said to be hydrophilic (likes water), if the contact angle is large the surface energy is low and the surface is said to be hydrophobic. On surfaces that are untreated (dirty or contaminated) the water droplet will bead up rather than spread out over the surface, where on a surface which has been treated the water droplet will spread out evenly. The wetability is related to the surface energy, the more wetable the surface the higher the surface energy. Goneometers and mechanical Contact Angle Measurements (CAM) devices allow precise measurement of the degree of wettability on the surface of a material. The lower the contact angle the more wettable the surface. The CAM is only a preliminary indication of the surface energy, and if adhesion is the goal a complete process including the application of adhesive and testing with a bond pull can then allow for a direct correlation between the contact angle measurement and the bond pull.

+ March 等离子技术 Plasma Technology 集成电路封装技术 IC Packaging Technology 成功应用
(Not All Plasma Systems Are The Same) + 集成电路封装技术 IC Packaging Technology (Not All Packages Are The Same) 成功应用 Successful Application of Plasma Technology for Integrated Circuit Packaging

March 产品 March Products

Equipment Solutions Batch vs. Automated

Batch System Solutions
AP-1000 AP-1000e8

AP-1000 Flexible Shelf Configuration Complete System Enclosure
PLC Controller Vertical Door Option e8 Option CE and SEMI S2-93 Compliant Applications Magazine Treatment Auer Boat Processing Wafer Cleaning MCM Carriers Boards

AP 1000 Vertical Door

AP-1000e8 Higher throughputs Improved uniformity Matrix/Array Pkgs
Metal Leadframes

Automated System Solutions
ITRAK XTRAK MultiTRAK

Automated System Solutions
Unparalleled Uniformity Compact Chamber Design Balanced Gas Flow Unique Vacuum Exhaust Guaranteed Repeatability Strip by Strip Processing Closed or Open Magazines No Pitch Restrictions Speed Total Overhead Time: Seconds Infeed Vacuum and Plasma Outfeed

ITRAK and XTRAK Strip Sized Chamber ITRAK Width 38-78 mm
Length 178 mm mm XTRAK Width mm Length mm PLC Controlled with Touch Screen Intuitive Graphical User Interface Statistical Data Gathering (SEMI E-10) Complete System Enclosure Full Front Access Self-Contained Handling System SMEMA 1.2

XTRAK System

XTRAK-IFP System

MultiTRAK System Multiple Strip Processing: Up to Seven
PC Controlled with Touch Screen Intuitive Graphical User Interface Statistical Data Gathering (SEMI E-10) Complete System Enclosure Full Front Access Compact Footprint Self-Contained Servo Motor Driven Handling System SEMI S2-93 SMEMA 1.2

MultiTRAK System Field Configurable Number of Tracks Width of Tracks

MultiTRAK System Part Dimensions: Width 16mm - 154mm 0.62” - 6”
Length 76mm -305mm 2” - 12” Handling System: Conveyor Belt w/ Pinch Wheels & Bridges Servo Driven Pusher Fiber-optic Sensor User Interface: PC w/ Touchscreen,Mouse & Keyboard Ancillary Equipment: 600 Watt RF Generator 15 CFM Pump Footprint: Width 1067mm (42”) Height mm (82”) Depth 864mm (34”)

MultiTRAK System Multiple Strip Processing Capability
Number of parts Minimum strip width Maximum strip width mm (0.62") mm (6.06") mm (0.62") mm (2.89") mm (0.62") mm (1.83") mm (0.62") mm (1.3") mm (0.62") mm (0.98") mm (0.62") mm (0.77") mm (0.62") mm (0.62") Maximum Part Length:305mm (12") Minimum Part Length: 76mm (3") Maximum Part Thickness:6.35mm (0.25")

Configurations Stand Alone In-Line Island Integration

Stand Alone

Inline Integration

Island Integration

CS-1701 Reactive Ion Etcher
Excellent for metal etching, silicide etching and etching of III-V compounds. Anisotropic etching of nitrides, oxides and polyimides. large DC bias. The ability to control process pressure independent of gas flow. Etch profiles ranging from anisotropic requiring high aspect ratios to sloped walls. Controllable Temperature

Plasma to Make Your Product ….
… And Make It Better

PLASMA TRAINING PROGRAM

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