Challenges in hardening technologies using shallow-trench isolation

Abstract

Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide.

Influence of total-dose radiation on the electrical characteristics of SOI MOSFETs

“…These defects can lead to enhanced radiation-induced charge trapping. It has also been shown that implant damage can cause significant radiation-induced degradation in gate and field oxides [11,16,17]. Thus, it is natural to expect that the very high-fluence implants used to fabricate SIMOX substrates (and some bonded oxide substrates) may cause numerous implant-related defects that might result in enhanced radiationinduced charge trapping in the buried oxide.…”

“…As is the case with gate and field oxides [11], the radiation response of buried oxides has been found to be highly dependent on the fabrication process [12,13]. Two common methods for fabricating SOI substrates are separation by implanted oxygen (SIMOX) and wafer bonding.…”

“…For radiation-induced charge buildup in field oxides (LOCOS or shallowtrench isolation), the worst-case bias configuration is typically the ON bias configuration (gate high, source and drain low) [11]. Similar to field oxides, the buildup of radiation-induced charge in SOI buried oxides is dominated by positive oxidetrapped charge.…”

Investigation of Hump Degradation by F-N stress for Narrow Width n-MOSFETs with Shallow Trench Isolation (STI)

“…[1] Possible processed induced leakage current path exist for STI, as illustrate fig 1. These paths consist of the corner/ sidewall leakage current path from source to drain in the n channel transistor and these leakage currents are responsible for the degradation in the retention time and power dissipation of logic circuits.…”

Including the effects of process-related variability on radiation response using a new test chip

“…Accurate assessment of effects such as transistor mismatch is not only required by commercial designs using advanced processes, but also required by space applications, since previous work has shown that total ionizing dose (TID) response is sensitive to process variations and layout [1]- [4]. Many space applications rely on commercial foundries to provide advanced process technologies, but how to enhance foundry process design kits (PDKs) accurately and quickly to address the space environment is another challenge.…”