The LPCVD system for use in the Micro/Nano Fabrication Center Michael J. Berman, MFC Manager Phone:

Agenda Tool overview Layout of tool and support items Gas –Type –Volume Safety –Systems –Training Abatement system

What is the LPCVD Tool? The LPCVD tool is a Low-Pressure Chemical Vapor Deposition System with 4 Process Tubes. The Tubes (and Processes) are: –Silicon nitride –Polysilicon –Low Temperature Silicon Dioxide (LTO) –Phosphorous doped (4%) LTO (PSG)

The System The process will: Have a working volume of 350mm long x 150mm diameter Have a processing pressure of about 100 to 300m Torr, and Use the following hazardous gases: –SiH4 (PSG, LTO & PSG) –PH3 (15% in SiH4) ( PSG only) –DCS (dichlorosilane--H2SiCl2) (Nitride only)

Layout of tool

Detailed Layout of System G1- O2 & NH3 Cabinet G2- SiH4, Ph3/SiH4 & DCS Cabinet G3- Gas Lines S1 & S2- SiH4 sensors E Main 480 v Box E Main System Power Cabinet

Detailed Layout 2 E v 200 amp power for pumps P Pumps E amp box AB-1-- Abatement system S-3– SiH4 sensor for exhaust EX-1-- Exhaust line

Overview of the Gas Flow (SiH4, 15% PH3 in SiH4 & DCS) A B C D E F G A -Gas Cabinets with Auto Purge Panels B -Double contained Stainless Steel Gas Lines C -The LPCVD System Tool D -4 Stainless Steel Exhaust Lines E -Vacuum Pump (one per tube) F -Gas Abatement System G -House Exhaust System

Overview of the Gas Flow G H I GExhaust HFan on roof ISmoke stack

Gas flows (in Standard Liters) Process flows: –N2 purge (all tubes before and after process) SL –Tube in standby --.2 SL –Silicon Nitride DCS--.2 SL NH3--.05SL –P doped SiO2 PH3 (15%)/SiH SL SiH4--.1 SL O SL N2– 3 SL –SiO2 SiH SL O2--.2 SL N2--.5 SL –Poly Silicon SiH SL Note: About 50% of the process gases become part of the film and do not enter the exhaust Pump Purge –In process tube-- 20 SL –Idle tubes-- 7 SL

Gas Flows Only one tube will be in process at any time. –Will be interlocked by the system software. –Other 3 tubes will be in standby Typical Flows (SiO2 Film) will be: –.05 SL SiH4 (process gas) –.6 SL N2 (stand by for other 3 tubes) –20 SL N2 pump bias (the tube in process) –21 SL N2 for the other 3 pumps –Total gas going into exhaust system: SL during process, with of which 41.6 is N2 During time of no process, the each tube will have.2 SL N2 flowing at the tube and 7 SL of N2 at the pumps or a total of 28.8 SL of N2

A--The Gas Cabinet The Gas Cabinet is/has: –Air Products with Gas Guard 450 Auto purge panels. –Self closing door/ports –Exhausted with > 200 fpm velocity –12 gauge steel –Negative Pressure (exhaust) interlocked to shutdown flow and give an alarm Gas Cabinet meets all of the requirements of the University. –Air flow/Exhaust will be checked after install before any gases are brought on site

A--Restricted Flow Orifices Pressures RFO / Flow Rate in SLPM (Peak) Gas Specific GravityFull0.006 "0.010"0.031"0.040"0.052" SiH % PH3/SiH Pressures RFO / Flow Rate in SLPM (Minimum) Gas Specific Gravity Empty (150) psig)0.006 "0.010"0.031"0.040"0.052"Desired Flow SiH % PH3/SiH DCS NH DCS is shipped as a liquefied gas under its own vapor pressure (9 70°F) for that reason, a RFO is not recommenced

A--Restricted Flow Orifices SiH RFO PH3 15% in SiH RFO NH RFO DCSRFO not recommenced

BDouble contained Stainless Steel gas lines The gas lines for the SiH4, PH3 in SiH4 & DCS will be: –Double contained Stainless Steel gas lines –Center line is ¼ in. –Outer line is ½ in. All contact with gases will be Stainless Steel or glass till the gas is exhausted on the pump. There will be a 20 + liters per min N2 added at the pump.

Gas Bottles

Gas used per 1,000 A (in SL) ProcessN2SiH4DCSNH3 PH3 (15%-SiH4) O2 Nitride PSG LTO Poly4501.4

Gas Volume Total Gas Volume for: –SiH4 –DCS –PH3 (15%- 85%-SiH4) Will be less than 20 Cu. Ft. –This is based on not having the H6 Storing Gas in Lab: Our plans are to store no more than 3 bottles in the lab, when a bottle is needing to be changed, a new bottle will be brought in and the old one removed.

Safety Issues for LPCVD System for SiH4 Gas Cabinet Pneumatically-controlled Gas Valves/Auto Purge for DCS, Sih4 & SiH4 (15% PH3) Interlock to stop flow based on: –Low Cabinet Exhaust –Electrical Power Failure –Gas Sensor –.5 TLV inside the Gas Cabinet (for SiH4 or HCL) –EMO/EMP (in any of the 3 locations) –Fail-closed based on the LPCVD tool going into an alarm mode Lights and horn sounds, if the.5 TLV level is crossed in the work area or with Gas Cabinet.

Safety Systems In the areas In the fab, in front of the LPCVD: –SiH4 to monitor area for.5 TLV levels. –Lights and horn that sound alarm in fab/chase. –An evacuation plan of area (see diagram, next pages). In the chase, behind LPCVD: –Identical SiH4 monitor in cabinet to monitor area for.5 TLV levels. –Lights and horn that sound/flash alarm in fab/chase –Light in the room leading into the chase and down the hallway in the chase (see diagram, next pages).

Evacuation of area Two types of Evacuation Plans: Scheduled –In the course of changing a gas bottle, or –When other PM activities may impede safety –All persons not taking part in the PM activates will leave both the fab and the chase. Unscheduled –On gas cabinet alarms and lights –All persons will evaluate the fab/chase based on the lights and horns

Alarms and lights Lights and horn placement will be as marked on the next pages. –Gas bottle change A do not Enter light will be at each door way to be used during gas bottle change. There will also be chains to block some areas of the fab during the bottle change. Light & horn will be turned on when the TLV for the gas cabinet or the work area is greater than.5 TLV, this will cause all persons to leave the fab and chase. There will also be lights for Do not enter at the doorways. The colors of the safety lights and type of horn are being work with Jose Arizpe, to match University/government standards. The system may at some future time be interconnect to the house fire/smoke system. –Based on future work this interconnection can: Set off the fire/smoke system Be set off by the fire/smoke system

Evacuation plan

SafetyThe gas Sensor The safety monitor is a product of Zellweger Analytics also known as Honeywell. The safety monitor is a Silane Low Level Sensor (SiH4), model MIDAS-S-SHL (which works with other gases, see diagram below). –With the lowest detectable limit (LDL) at 0.18 ppm –Minimum alarm set point at 0.24 ppm GasTLV (ppm).5 TL V Concent ration (ppm) Reading (Silane Sensor) (ppm) Minimum Detectable concentration (ppm) Reading for.5 TLV (ppm) Silane DCS HCL PH3 (15% in Silane) Silane (85% -15% PH3)

Safety Training Gas bottle changes: –PPE will be SCBA, flame suit (including face shield). SCBA training is being reviewed and planned with Julia Rosen of Risk Management & Safety Basic training will be completed before any of the toxic gases are brought on site –The person using the PPE will be trained and approved by the ERT Team leader based on inputs by PPE, gas vendor or outside sources. –Each time there is a bottle change in addition to the person performing the bottle change, a second person will be in the same PPE with the same level of training, near by to assist if there is a problem. All lab personal will be trained in proper knowledge & evacuation. All current users will be trained in proper knowledge & evacuation. All new users will be trained before they receive access Training information will also be available through our website at

ERT MFC will put into action an ERT team for the lab. Gregg Cure will assist as team leader. –Gregg brings experience with ERT from working with other fabs All staff and users will receive training to learn policies and procedures, safety and to understand ERT functions ERT is offered on campus through the Universitys Facilities Department, Spill Control Unit. Gas training (PPE, gas vendor and others, if needed) –Bottle changes –Leak resolution ERT will be defined and reviewed with RM before the gases are brought on site

Abatement System A Centrotherm Dry Resin canister for Gas Abatement System will be used on the output end of the pumps. This system will: React & Remove SiH4, DCS, NH3 & PH3 –All 4 gases should be at or near the TLV before going into the exhaust –The exhaust has a flow of about 300,000,000 sccm Sensor on the output of the Abatement System will be set to about 2X TLV for SiH4 before going into exhaust. An alarm will be used to signal when to change a canister. Sensor will have a go/no-go light Or if there is a problem with the sensor system

Exhaust System Output Output is at or near TLV before going into the Exhaust system The exhaust is > 300,000,000 sccm

Procurement spec for: Silane Silane Name of gas SiH4 Chemical formula of gas Semiconductor Grade 4N8 Purity 0 % of secondary gas Maximum amount of gas in bottle –8.0 cu ft –365 grams weight 350 CGA fitting Bottle size name Cylinder UF Bottle size dimension 6 x 19 (D x H) Restricted Flow Orifices MSDS on file Approved vendor list –Matheson-Trigas

Procurement spec for: 15% PH3 in Silane Name 15% PH3 in Silane Chemical formula of gas PH3 (15%) in SiH4 Semiconductor Grade Purity % of secondary gas Maximum amount of gas in bottle –1.6 cu ft –365 grams weight 350 CGA fitting Bottle size name Cylinder SA Bottle size dimension 2 x 12 (D x H) Restricted Flow Orifices MSDS on file Approved vendor list –Matheson-Trigas

Procurement spec for: DCS Name Dichlorosilane (DCS) Chemical formula H2SiCl2 Semiconductor Grade 2N Purity 0 % of secondary gas Maximum amount of gas in bottle –8.4 cu ft –2.2 LBS. weight 678 CGA fitting Bottle size name Cylinder JF Bottle size dimension 4 x 13 (D x H) Restricted Flow Orifices none (due to the low pressure) MSDS on file Approved vendor list –Matheson-Trigas

Procurement spec for: Ammonia Name Ammonia Chemical formula NH3 Semiconductor Grade 5N Purity Purity 0 % of secondary gas Maximum amount of gas in bottle –50 LBS +- 10% weight 660 CGA fitting Bottle size name Cylinder QF Bottle size dimension 9 x 51 (D x H) Restricted Flow Orifices MSDS on file Approved vendor list –Matheson-Trigas