Evaluation of Anisotropic Biaxial Stress Induced Around Trench Gate of Si Power Transistor Using Water-Immersion Raman Spectroscopy

Self Cite

We evaluated the residual stress of the silicon nitride (SiN) fine pattern structure in order to quantitatively predict the occurrence of wiggling, which causes device failure. UV Raman spectroscopy showed an increase of tensile stress in Si substrate with increasing etching time, and the tensile stress in Si substrate was caused by the enhancement at the very edge of the fine pattern and the increase in the amount of over-etching. It was also confirmed that the edge enhanced effect can be obtained by using a UV laser for fine patterns, so that the Raman intensity from Si (amorphous and crystal) increased significantly with the etching time of the pattern. Furthermore, using water-immersion Raman spectroscopy, we evaluated the anisotropic biaxial stress applied to the fine patterns and showed occurrence of strain relaxation. The wiggling, therefore, occurs due to the huge anisotropic stresses induced in the Si substrates.

Section: Experimental Methodsmentioning

confidence: 99%

Section: Investigation Of Anisotropic Biaxial Stress Measurement By W...mentioning

confidence: 99%

Stress evaluation induced by wiggling silicon nitride fine pattern using Raman spectroscopy

Koharada

Yokogawa

Sawamoto

et al. 2020

Self Cite

“…As Raman shift is significantly affected by the manufacturing process, the differences between experimental and simulated values can be attributed to the non-uniform oxide film. 36) In practical manufacturing processes, there may be some non-uniformity in the thickness of the oxide layer, especially in thicker oxide layers. This non-uniformity could potentially lead to a large discrepancy between w S ∆ and w .…”

Section: ∆ ( )mentioning

confidence: 99%

Study on stress in trench structures during silicon IGBTs process-oxidation

Cai,

Yuan,

Miyamura

et al. 2024

In silicon insulated gate bipolar transistors (IGBTs), the trench gate structure is used to achieve smaller cell size and lower ON resistance, and thereby reduces energy loss. However, the thermal process can cause large stress near the trench and sometimes degrades device performance. This study proposed a three-dimensional model of a silicon chip with trench structures to analyze the stress distribution induced by thermal process around the trench, the scribe line, and the bottom surface of the chip. The calculated stress is in good agreement with measurement by Raman spectroscopy. The mesa top has much higher stress than the scribe line and the bottom surface. The stress depends on oxide thickness and the size scaling may reduce the stress.

“…Consequently, IGBTs have the characteristics of high power and high frequency and, therefore, are used as mainstream power switching devices nowadays. 1,2) Various IGBT advances have been proposed to achieve low onresistance, such as trench structure formation, [3][4][5] IE (injection enhancement) effect utilization, [6][7][8] and introduction of a field stop layer. 9,10) The IE effect leads to an increase in the breakdown voltage of the IGBT because on-resistance can be reduced without changing the thickness of the base layer.…”

Section: Introductionmentioning

confidence: 99%

Evaluations of minority carrier lifetime in floating zone Si affected by Si insulated gate bipolar transistor processes

Kobayashi

Yokogawa

Kinoshita

et al. 2019

This study evaluates minority carrier lifetime in floating zone Si affected by advanced and conventional Si IGBT (insulated gate bipolar transistor) processes. Si gate oxidations reduce lifetime due to the formation of interface states between the Si and the oxide. As a result, cross-sectional photoluminescence imaging shows that the lifetime around a trench is lower than that in the bulk region. The high temperature thermal treatment for B-base/P-emitter layer activation after gate oxidation improved the interface, thus resulting in the recovery of the lifetime. TEM observations reveal that the (110) trench surface shows irregular contrast while the (100) surface shows relatively smooth contrast, which is consistent with the lifetime result of “trench side wall surface (100)” > “trench side wall surface (110).” Our study conclusively clarifies that lifetime is correlated with the SiO2 surface state.