Reliability results of HBTs with an InGaP emitter

Abstract

0183 cwhitman@rfmd com 1. Abstract Accelerated lifetest results are presented on HBTs with InGaP emitters. The data from this experiment are analyzed in several ways. An Arrhenius plot indicates the existence of a tempemture dependent activation energy, E. A low Ea mechanism dominates above Tj 380°C and a high Ea mechanism dominates at lower temperature. The critical transition temperature between regimes is determined using the method of maximum likelihood. The difference in Ea's between low and high temperature regimes is statistically significant.The HBTs are divided into two groups, A and B. Group A contains a total of 116 devices from II wafer lots. The analysis suggests further splitting group A into high and low temperature subgroups.The A-high H-BTs are run stressed at Tj's of 379, 391 and 413 OC and A-low devices are tested at Tj's of 312, 355 and 367 OC. Group B is composed of HBTs from 7 lots from an earlier qualification and are stressed at Tj of285, 305 and 325 OC.A comparison is made between estimates from degradation measurements performed at temperature vs. 40°C for group A-low. No significant difference is observed indicating that beta degradation can be monitored at temperature only and cooling to low temperature is not necessary. Further, the predictions from group A-low and group B data are found to be in good agreement indicating that very high junction temperatures can still provide good estimates of lower temperature behavior.By the method of maximum likelihood, the group A-low data predicts a MTTF at T-= 125°C of 7.6 x 109 hours with 95% CBs of [6.4 x 108, 8.9 x I o'1. Given the typical industry standard of I x 1 06 hours, the reliability requirements are easily met.It is suggested that the standard of lx 106 hours does not adequately take failure time variation into account and that a better specification is in terms of FITs (fails in time). The 20 year average FIT rate at 125 IC is found to be negligible. Assuming a much higher junction temperature of 200 IC, the average failure rate climbs to 0.65 FITs with an upper 95% confidence bound of-6 FITs.

ALD HfO2 and Al2O3 as MIM Capacitor Dielectric for GaAs HBT Technology

“…However, the dielectric constant of this silicon nitride is relatively low and ranges only from 6 to 7, depending on the deposition method, chemistry, and condition (1,(4)(5)(6)10,11). There are a few other dielectric materials that have been considered and used as capacitor dielectric in GaAs technologies, including silicon dioxide (SiO 2 ), silicon oxynitride (SiON), and tantalum pentoxide (Ta 2 O 5 ) (1,2,5,6,9,(26)(27)(28)(29)(30). These films, along with silicon nitride, are typically deposited using physical vapor deposition (PVD) and plasma-enhanced chemical vapor deposition (PECVD) methods, both of which are compatible with GaAs processing and can be performed at 300ºC or lower.…”

Effects of Deposition Method of PECVD Silicon Nitride as MIM Capacitor Dielectric for GaAs HBT Technology

“…Due to the increasing demand for capacity and revenue, the die size in semiconductor wafer manufacturing must be reduced. One method to reduce the die size of circuit designs is to increase the capacitance density of metal-insulator-metal (MIM) capacitor device, which is a key passive component in GaAs-based technologies, including hetero-junction bipolar transistor (HBT) technology [1][2][3][4][5][6][7][8][9][10]. The capacitance density of capacitors can be increased by simply reducing the thickness of the capacitor dielectric or insulator.…”

“…The silicon nitride and silicon oxynitride as capacitor dielectric is typically deposited using plasma-enhanced chemical vapor deposition (PECVD) [3,4,7,8,23], while the higher dielectric constant materials are typically deposited using sputtering, atomic layer deposition (ALD), or other deposition methods [17,19,20]. The most common dielectric material used as the insulator or dielectric for MIM capacitors in GaAs HBT technology is PECVD silicon nitride, due to its good electrical characteristics, including relatively high dielectric constant, high dielectric breakdown voltage, and low leakage current, and due to its compatibility with GaAs processing [1][2][3][4]7,8]. The application of PECVD Si 3 N 4 film, which can be deposited at temperature of 300 o C or lower, will minimize device degradation that may occur when GaAs devices are exposed to higher processing temperatures [4,8,10,[24][25][26].…”