Reliability Characterization in consideration of Self-Heating in FinFET Technology

다국어 초록 (Multilingual Abstract)

With technology node scaling, fin shape (3D) engineering enables higher performance for the smaller fin pitch and reducing footprint. Generally, FinFETs have been engineered to be taller and narrower for better electrostatics and performance at lower VT operation. The taller the fin height and the narrower the fin bottom width allows more difficult to remove the heat generated at the top of the fin. It is discussed that the self-heating only matters during device operation and mainly affects hot carrier injection (HCI) aging from device perspective, more severe in PFETs than in NFETs due to higher Ea. Increase of fin self-heating effect and potential reliability issues must be well understood, characterized, and modeled for design of products. By characterizing the duty in AC operation, fin self-heating on high speed logic could be mitigated or can be built into the design by embedding self-heating model into SPICE simulation along with aging run. Self-heating effect have not been very apparent on the Ring Oscillators with their very high frequency operation and voltages around 1/2xVdd during switching transitions even for long durations (of several hundred hours of stress). Any digital logic circuits that operate on the giga-hertz (GHz)-level with very low duty would most practically experience little fin self-heating impacts. As circuits do continue to operate longer, there can be residual impact of self-heating effect that gets accumulated as time elapses. Therefore, those effects must be carefully taken into account in design by running various duty scenarios. On analog devices and circuits that have more static bias and higher duty cycles, typically longer channel devices are used to minimize the process variations. A careful reliability characterization in consideration of self-heating effect is needed as fin dimension continues to scale very aggressively.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Experimetal work 3
• 2.1 FinFET Technology Scaling 3
• 2.2 Characterization Methods in advanced FinFETs 6
• 2.2.1 Hot Carrier Injection 6
• 2.2.2 Self-Heating Effect 7
• 2.2.3 Ring Oscillator Aging 11
• 3. Self-heating Effect in FinFET Reliability 13
• 3.1 Hot Carrier Analysis in FinFET 13
• 3.2 Self-heating Effect in FinFET 15
• 3.3 New methodology to decouple SHE from HCI 17
• 3.4 Self-heating driven drain-biased TDDB 24
• 4. HCI Effect in FinFET Ring Oscillator 30
• 4.1 Ring Oscillator Degradation 30
• 4.2 New RO structures to decouple BTI from HCI 31
• 4.3 HCI Duty Cycle in RO 35
• 5. Conclusion 38
• Reference 39
• Korean Abstract 42