1 High Performance ALD HfO2-Al2O3 Laminate MIM Capacitors for RF and Mixed Signal IC ApplicationsHang Hu1, Shi-Jin Ding1, HF Lim1, Chunxiang Zhu1, M.F. Li1, 2, S.J.Kim1, XF Yu1, JH Chen1, YF Yong1, Byung Jin Cho1, D.S.H. Chan1, Subhash C Rustagi2, MB Yu2, CH Tung2, Anyan Du2, Doan My2, PD Foo2, Albert Chin3, Dim-Lee Kwong41SNDL, Dept. of ECE, National Univ. of Singapore, Singapore,2Institute of Microelectronics, Singapore,3Dept. of Electronics Eng., National Chiao Tung Univ., Taiwan4Dept. of Electrical & Computer Eng., Univ. of Texas, Austin, TX 78712, USASilicon Nano Device Laboratory / Dept of ECE
2 Outline of Presentation MotivationExperimentResults and DiscussionRF characterizationDC propertiesReliability and lifetimeHigh-κ MIM capacitors comparisonConclusions
3 Voltage linearity (ppm/V2) Voltage linearity (ppm/V) MotivationMixed signal MIM capacitor requirementYear of Production20032004200520062007201020132016Analog capacitorDensity (fF/µm2)3471015Voltage linearity (ppm/V2)100Leakage (fA[pF•V]RF bypass capacitor891112172023Voltage linearity (ppm/V)1000The International Technology Roadmap for Semiconductors, 2002 Edition
4 MotivationSiO2 and Si3N4 MIM capacitors usually provide low capacitance density of ~1 fF/μm2.High-k dielectrics needs to be used for future MIM application according to ITRS roadmap.HfO2 is a promising high-k material for MIM capacitor. However fast oxygen diffusion.Al2O3 have the advantage of large band gap, low oxygen diffusivity, however only middle k value.
5 TEM photo of 13 nm laminate film Experiment4 μm SiO2 deposition on Si substrate for isolationBottom electrode deposition (Ta/TaN)Transmission line formationDielectric deposition by atomic layer deposition (ALD)Al2O3 (1nm)/HfO2 (5nm) laminateAl2O3 as electrode contacting layers13, 31, and 43 nm used in our workTEM photo of 13 nm laminate film
6 Experiment Post deposition anneal (420oC) Contact hole etching Top metal deposition (TaN/Al) and patterningFinal Device structure for characterizationMIM structureDummy device
7 Capacitor modeling in RF regime I. RF capacitor modelCapacitor modeling in RF regimeEquivalent circuit diagram for MIM capacitormodeling in RF regime
8 I. S-parameter simulation 13 nm31 nm43 nmMeasured and simulated S-parameters for laminateMIM capacitors by IC-CAP using SPICE3 simulator.
9 I. High frequency response High frequency response of laminate MIMcapacitors from 50 MHz to 20 GHz
10 I. Cap. versus frequencyThe frequency dependence of capacitance densityof laminate capacitors (k ~19).
11 II. J-V characteristics Typical J-V characteristics of laminate MIM capacitors
12 II. J-V characteristics Leakage obtained at different temperatures for 13nm MIM capacitor (normalized to JRT: leakagemeasured at room temperature)
13 II. Conduction mechanism Conduction mechanisms of 13 nm laminate MIMcapacitor, showing Pool-Frankel conduction athigh field.
14 II. CV characteristicsQuadratic (α) and linear (β) VCCs of laminate MIMcapacitors with thicknesses of 13, 31 and 43 nm
15 II. CV characteristics Thickness dependence of quadratic VCC (α) for laminate MIM capacitors. The implication issignificant for the scaling of the high-k dielectrics.
16 II. CV characteristics Frequency dependence of quadratic VCC α for laminate MIM capacitors
17 II. CV characteristics Quadratic VCC as a function of stress time. The inset shows time dependence of linear VCC .
18 II. CV characteristics Time dependence on VCCs and leakage, under stress condition. The recovery of leakage and VCCsmay further prolong lifetime under AC condition.
19 II. TCC properties TCC values for laminate MIM capacitors with three different thicknesses
20 III. Constant voltage stress Stress time dependence of leakage for a freshdevice up to 2000s. The device was re-stressed andre-measured after interrupting stress for 10 hours.
21 III. Breakdown characteristics Breakdown and leakage characteristics of 13 nmlaminate MIM capacitors as a function of stress time.
22 III. Lifetime projection Life time projection of 13 nm laminate capacitor, using50% failure time criteria, the extrapolated voltage for10 years lifetime is 3.3 V.
23 IV. High-κ MIM cap. comparison ReferenceThis workDielectricHfO2 (ALD)Ta2O5AlTaOx (PVD)Ta2O5 (CVD)Tb doped HfO2 (PVD)Hf/Al laminate (ALD)Capacitance density (fF/µm2)139.210913.312.8Leakage (A/cm2)—VCC607 ppm/V853 ppm/V22060 ppm/V 3580 ppm/V22818 ppm/V22050 ppm/V475 ppm/V2332 ppm/V2667 ppm/V2211 ppm/V1990 ppm/V2TCC (ppm/oC)~200255123198Laminate capacitor is among one of the best for RF capacitor application.. XF Yu et al. EDL. Vol. 24, 2003.. Tsuyoshi. I et al. IEDM 2002, p.940.. C. H. Huang, et al. MTT-S. Y. L. Tu. et al VLSI symp. 2003, p.79.. S.J. Kim et al. VLSI symp. 2003, p.77.
24 Conclusions High performance HfO2/Al2O3 laminate MIM capacitors have been demonstrated for the first time.The ALD laminate MIM capacitors exhibit high Cdensity, superior dielectric stability up to 20 GHz,low leakage current, and promising reliability.For 13 nm laminate MIM capacitor C density ~12.8 fF/μm2 up to 20 GHz ~ 211 ppm/V, Leakage ~ 7.45 nA/cm2 at 2 V Meets all requirements for RF bypass capacitor
25 AcknowledgmentThis work was supported by Institute of Microelectronics (Singapore) under Grant R and the National University of Singapore under Grant R