Stress Engineering of SiNx Films for Modifying Optical and Mechanical Properties

Abstract

This article presents an approach for the adjustment of residual stress in silicon nitride (SiNx) films by constructing a composite multilayer structure. Curvature and Raman measurement results indicate that with the introduction of a 240-nm-thick SiO 2 sublayer, the residual stress in a 110-nm-thick SiNx film varies dramatically from high tensile stress (+358 MPa) to low compressive stress (-57 MPa). The adjustment of film stress leads to the improvement of film quality and the increase of refractive index. However, it also leads to the decreases of Young's modulus and film hardness of SiNx. Particularly, the optical band gap of SiNx remains almost unchanged during the process. This work demonstrates the practical feasibility of modifying the physical properties of SiNx with the film stress, and suggests a new physical route to stress engineering of SiNx films for microelectronic and optoelectronic applications.

A comparison of structures and properties of SiNx and SiOx films prepared by PECVD

“…In addition, low stress SiNx films can be yielded by using some modified systems, such as catalytical CVD (Cat-CVD) [30] and dualfrequency PECVD (DF-PECVD) [31]. Different from all these conventional methods, we recently reported a novel approach to the control of film stress in SiNx by constructing a composite multi-layer structure [32]. Since various Si-N groups are contained in the resulting SiNx, one might thus predict that the film stress in SiNx could be rationally adjusted by controlling the ratio among the Si-N groups, which has also been recently verified by our experiments [29].…”

Role of advanced oxidation processes in lignocellulose pretreatment towards biorefinery applications: a review on emerging trends and economic considerations

“…The combination of photochemical oxidation and EO yielded synergistic effects, particularly in the oxidation of lignin into valuable products such as vanillic acid. 55 This approach is efficient to transform lignin into valuable chemicals. PO selectively breaks down lignocellulose, forming substrate-based radical intermediates engaged in various reactions, including single-electron and electron and proton transfer.…”

Molecular mechanism of the transformation of oxidized lignin to N-substituted aromatics

“…6,7 There have been numerous publications devoted to the effective breaking of C-O and/or C-C bonds in lignin model compounds and extracted lignin samples. [8][9][10][11][12][13][14][15][16][17][18][19][20] Compared to the comprehensive research on the breaking of C-O bonds, the cleavage of C-C bonds in lignin is challenging as the process requires harsh reaction conditions such as using transition metal catalysts or supercritical water or strong acids/bases at high temperatures. 21,22 Since the pioneering reports of Beckham et al 23 that the oxidation of α-OH in a β-O-4 linkage to ketone would realize the breaking of the C β -O bonds by decreasing its dissociation energy, methodologies using oxidized lignin to cleave C-C bonds have opened a new door to achieving lignin degradation more effectively.…”