16 Reliability Simulation |
541 |
Vds0 State Diffusion @ Vg=–5
Vertical (um)
GaN |
Oxide |
Nitride |
Val-1e+18 |
Val-8e+19 |
AIGaN |
Metal |
Val-1e+19 |
Val-9e+19 |
Val-8e+19 |
–0.02
–0.01
0
0.01
Gate Width=0.3um
0.02
0.2 |
0.1 |
0 |
–0.1 |
–0.2 |
Lateral (um)
Fig. 16.18 Simulation figure of impurity diffusion in the VDS ¼ 0 state with VG ¼ 5 V, VD ¼ VS ¼ 30 V. Concentration contours show enhanced diffusion on both sides of gate where compressive strains are higher
The resultant metal impurity profile is treated as profile of charged trapping sites that are added to Poisson’s equation. The assumption of permanent trapped charge as used in the model is based on the observation of nonrecoverable changes in IDS during off-state step-stress experiments performed by [37] and nonrecoverable changes in trap density observed by [33]. Figure 16.20 shows the simulation of the altered structures IV characteristics. For a 10-V negative gate bias with VDS equal to 35-V stress, a 10.6% reduction in gate current is observed. Increasing current degradation is observed with increasing voltage stress on the device, in accordance with observed device behavior.
16.5Conclusion
The FLOORS platform offers a capable way to simulate degradation in III-V devices. A variety of physics can be included. This chapter shows examples of self-heating simulation in HEMTs, adjustable MEM mirrors responding to heat
542 |
M.E. Law et al. |
Off State Diffusion @ Vg=–10
Vertical (um)
GaN |
Oxide |
Nitride |
Val-1e+18 |
Val-8e+19 |
AIGaN |
Metal |
Val-1e+19 |
Val-9e+19 |
Val-8e+19 |
–0.02
–0.01
0
0.01
Gate Width=0.3um
0.02
–0.2 |
–0.1 |
0 |
0.1 |
0.2 |
Lateral (um)
Fig. 16.19 Simulation figure of impurity diffusion in the off state with VG ¼ 10 V, VDS ¼ 30 V. Concentration contours show deeper enhanced diffusion at drain edge(right side) of gate where compressive strains are higher
Fig. 16.20 Current degradation in a HEMT for devices showing metal in diffusion in the gate region of the device
16 Reliability Simulation |
543 |
generation from current flow, and fully coupled thermal, electrical, and mechanical simulation of device structures.
Using FLOORS, two degradation examples were simulated. First, a simulation of the degradation of oxide materials under radiation as a function of hydrogen ambient was shown. Full models of hole motion, molecular and atomic hydrogen were shown fully coupled with reactions occurring at oxide vacancy defects. Second, a full simulation of the degradation behavior of GaN HEMTs in the off state has been performed. The degradation was modeled as compressive straindriven impurity diffusion into the AlGaN layer and has accounted for both a critical voltage and a subsequent decrease in IDS.
References
1.D. Scharfetter, H. Gummel, IEEE Trans. Electron Devices 16(1), 64–77 (1969)
2.M.R. Pinto, PhD thesis, Stanford University (1990)
3.R. Bank, D. Rose, W. Fichtner, IEEE Trans. Electron Devices 30(9), 1031–1041 (1983)
4.J. Machek, S. Selberherr, IEEE Trans. Electron Devices 30(9), 1083–1092 (1983)
5.S. Micheletti, Comput. Vis. Sci. 3, 177–183 (2001)
6.D. Cummings, M.E. Law, S. Cea, T. Linton, SISPAD (September 2009)
8.G. Wachutka, IEEE Trans. Comput.-Aided Des. 9(11), 1141–1149 (1990)
9.S.P. Gaur, D.H. Navon, IEEE Trans. Electron Devices ED-23, 50–57 (1976)
10.M.S. Adler, IEEE Trans. Electron Devices ED-25, 16–22 (1978)
11.H. Elschner, Nachrichientech. Electron 29, 415–418 (1979)
12.A. Chryssafis, W. Love, Solid-State Electron. 22, 249–256 (1979)
13.A. Venkatachalam, W.T. James, S. Grahm, Semicond. Sci. Technol. 26, 085027 (2011) (6 pp.)
14.F. Gao, H. Lo, R. Ram, T. Palacios, Device Research Conference, June 2010, pp. 127–128
15.M. der Maur, G. Penazzi, G. Romano et al., IEEE Trans. Electron Devices 58(5), 1425–1431 (2011)
16.D. Horton, F. Ren, L. Lu, M.E. Law, An Electro-Mechanical Simulation of Off State AlGaN/ GaN Device Degradation, Proceedings of the International Reliability Physics Symposium, April 2012
17.T.P. Ma, P.V. Dressendorfer (eds.), Ionizing Radiation Effects in MOS Devices and Circuits
(Wiley, New York, 1989)
18.R.A. Weeks, Paramagnetic resonance of lattice defects in irradiated quartz. J. Appl. Phys. 27(11), 1376–1381 (1956)
19.P.M. Lenahan, P.V. Dressendorfer, Hole traps and trivalent silicon centers in metal/oxide/ silicon devices. J. Appl. Phys. 55(10), 3495–3499 (May 1984)
20.J.F. Conley Jr., P.M. Lenahan, Room temperature reactions involving silicon dangling bond centers and molecular hydrogen in amorphous SiO2 thin films on silicon. IEEE Trans. Nucl. Sci. 39(6), 2186–2191 (Dec. 1992)
21.J.F. Conley Jr., P.M. Lenahan, Molecular hydrogen, E0 center hole traps, and radiation induced interface traps in MOS devices. IEEE Trans. Nucl. Sci. 40(6), 1335–1340 (1993)
22.X.J. Chen, H.J. Barnaby, B. Vermeire, K. Holbert, D. Wright, R.L. Pease, G. Dunham, D.G. Platteter, J. Seiler, S. McClure, P. Adell, Mechanisms of enhanced radiation-induced degradation due to excess molecular hydrogen in bipolar oxides. IEEE Trans. Nucl. Sci. 54(6), 1913–1919 (2007)
23.N.S. Saks, D.B. Brown, Observation of H + motion during interface trap formation. IEEE Trans. Nucl. Sci. 37(6), 1624–1631 (1990)
544 |
M.E. Law et al. |
24.S.N. Rashkeev, D.M. Fleetwood, R.D. Schrimpf, S.T. Pantelides, Defect generation by hydrogen at the Si-SiO2 interface. Phys. Rev. Lett. 87(16), 165506 (2001)
25.B.R. Tuttle, D.R. Hughart, R.D. Schrimpf, D.M. Fleetwood, S.T. Pantelides, Defect interactions of H2 in SiO2: Implications for ELDRS and latent interface trap buildup. IEEE Trans. Nucl. Sci. 57(6), 3046–3053 (2010)
26.T.R. Oldham, Ionizing Radiation Effects in MOS Oxides (World Scientific, River Edge, 1999), pp. 13–17
27.M.R. Shaneyfelt, D.M. Fleetwood, J.R. Schwank, K.L. Hughes, Charge yield for cobalt-60 and 10-keV X-ray irradiations of MOS devices. IEEE Trans. Nucl. Sci. 38(6), 1187–1194 (1991)
28.S.R. de Groot, P. Mazur, Non-Equilibrium Thermodynamics (North-Holland Publishing Company, Amsterdam, 1963)
29.N.L. Rowsey, M.E. Law, R.D. Schrimpf, D.M. Fleetwood, B.R. Tuttle, S.T. Pantelides, IEEE Trans. Nucl. Sci. 58, 2940 (2011)
30.P.M. Fahey, P.B. Griffin, J.D. Plummer, Point defects and dopant diffusion in silicon. Rev. Mod. Phys. 61, 289–384 (Apr 1989)
31.R.L. Pease, P.C. Adell, B.G. Rax, X.J. Chen, H.J. Barnaby, K.E. Holbert, and H.P. Hjalmarson,
The effects of hydrogen on the enhanced low dose rate sensitivity (ELDRS) of bipolar linear circuits, IEEE Trans. Nucl. Sci., vol. 55, no. 6, pp. 3169–3173, Dec. 2008
32.N.L. Rowsey, M.E. Law, R.D. Schrimpf, D.M. Fleetwood, B.R. Tuttle, S.T. Pantelides,
Radiation-induced oxide charge in lowand high-H2 environments. RADECS’11 Proceedings, Sevilla, Spain, Sept. 2011
33.M. Kuball, M. Tapajna, R.J.T. Simms, M. Faqir, U.K. Mishra, Microelectron. Reliab. 51(2), 195 (2011)
34.L.Liu, F. Ren, S.J. Pearton, R.C. Fitch, D.E. Walker, K.D. Chabak, J.K. Gillespie, M.Kossler, M. Trejo, David Via, and A. Crespo, Investigating the effect of off-state stress on trap densities in AlGaN/GaN high electron mobility transistors J. Vac. Sci. Technol., B. Microelectron.
Nanom. Struct. (2011)
ˇ
35. M. Tapajna, U. K. Mishra, and M. Kuball Importance of impurity diffusion for early stage degradation in AlGaN/GaN high electron mobility transistors upon electrical stress Appl. Phys. Lett. 97, 023503 (2010)
36. K.C. Hall, S.W. Leonard, H.M. van Driel, A.R. Kost, E. Selvig, D.H. Chow, Appl. Phys. Lett. 75(26), 4210 (1999)
37. J. Joh, J.A. del Alamo, J. Electron Device Lett. 29(4), 287 (2008)