Rapid Thermal Annealing for Residual-Stress Relaxation in Undoped or Doped Polysilicon Thin Films

1998 ◽  
Vol 546 ◽  
Author(s):  
Xin Zhang ◽  
Tong-Yi Zhang ◽  
Yitshak Zohar
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Stress Evolution ◽  
Before And After ◽  
Polysilicon Films ◽  
Compressive Residual Stresses

AbstractThe residual stress in doped and undoped polysilicon films, before and after rapid thermal annealing (RTA), is investigated using both wafer-curvature and micro-rotating structures techniques. Microstructure characterization has been conducted as well to understand the mechanism of the stress evolution. The results show that the compressive residual stresses in undoped polysilicon films can be reduced or eliminated within a few seconds RTA. Surface nitridation and grain growth are identified as the mechanisms responsible for the stress evolution.

Fem Simulation of Micro-Rotating-Structures and Their Applications in Measurement of Residual Stresses in Thin Films

1997 ◽  
Vol 505 ◽  
Author(s):  
Xin Zhang ◽  
Tong-Yi Zhang ◽  
Yitshak Zohar
Keyword(s):  
Thin Films ◽  
Residual Stresses ◽  
Fem Simulation ◽  
Sensitivity Factor ◽  
Local Measurement ◽  
Micro Structure ◽  
Micro Raman Spectroscopy ◽  
Before And After ◽  
Polysilicon Films ◽  
Simulation Results

ABSTRACTFEM simulation of micro-rotating-structures was performed for local measurement of residual stresses in thin films. A sensitivity factor is introduced, studied and tabulated from the simulation results. The residual stress can be evaluated from the rotating deflection, the lengths of rotating and fixed beams, and the sensitivity factor. The micro-structure technique was applied to measure residual stresses in both silicon nitride and polysilicon thin films, before and after rapid thermal annealing (RTA), and further confirmed by wafer curvature method. Residual stresses in polysilicon films at different RTA stages were also characterized by micro-Raman spectroscopy (MRS). The experimental results indicate that micro-rotating-structures indeed have the ability to measure spatially and locally residual stresses in MEMS thin films with appropriate sensitivities.

Polycrystal Plasticity Modeling of Cyclic Residual Stress Relaxation in Shot Peened Martensitic Gear Steel

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Rajesh Prasannavenkatesan ◽  
David L. McDowell
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Shot Peening ◽  
Cyclic Plasticity ◽  
Residual Stress Field ◽  
Residual Stress Relaxation ◽  
Gear Steel ◽  
Polycrystal Plasticity ◽  
Compressive Residual Stresses

Using a three-dimensional crystal plasticity model for cyclic deformation of lath martensitic steel, a simplified scheme is adopted to simulate the effects of shot peening on inducing initial compressive residual stresses. The model is utilized to investigate the subsequent cyclic relaxation of compressive residual stresses in shot peened lath martensitic gear steel in the high cycle fatigue (HCF) regime. A strategy is identified to model both shot peening and cyclic loading processes for polycrystalline ensembles. The relaxation of residual stress field during cyclic bending is analyzed for strain ratios Rε=0 and −1 for multiple realizations of polycrystalline microstructure. Cyclic microplasticity in favorably oriented martensite grains is the primary driver for the relaxation of residual stresses in HCF. For the case of Rε=−1, the cyclic plasticity occurs throughout the microstructure (macroplasticity) during the first loading cycle, resulting in substantial relaxation of compressive residual stresses at the surface and certain subsurface depths. The initial magnitude of residual stress is observed to influence the degree (percentage) of relaxation. Describing the differential intergranular yielding is necessary to capture the experimentally observed residual stress relaxation trends.

scholarly journals Influence of Vibration and Heat Treatment on Residual Stress of a Machined 12%Cr-Steel

2014 ◽  
Vol 996 ◽  
pp. 609-614 ◽  
Author(s):  
Lin Peng Ru ◽  
Johan Moverare ◽  
Pajazit Avdovic ◽  
Annethe Billenius ◽  
Zhe Chen
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Surface Layer ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Thin Surface Layer ◽  
Microstructural Changes ◽  
Low Level ◽  
Stress Relieving ◽  
Compressive Residual Stresses

In this paper we investigated the influence of vibratory stress relieving technique, which is widely used for stress relaxation of weld and casting components/structure, on machining residual stresses in a ring-component of 12%Cr-steel. It was shown that the employed vibratory treatment, without significantly altering the microstructure, turned the surface layer from tension into compression but retained the compressive residual stresses in the subsurface. In comparison, a stress relieving heat treatment, included as a reference in the study, removed completely the surface tensile residual stresses and reduced the subsurface compressive residual stresses to a low level. Significant microstructural changes in the form of recrystallization also occurred in a thin surface layer of the machining affected zone after the heat treatment.

Stability of Residual Stresses in Ultrasonic Surface Deep Rolling Treated Ti-6Al-4V Alloy under Cyclic Loading

2016 ◽  
Vol 853 ◽  
pp. 173-177 ◽  
Author(s):  
Miao Dong Mao ◽  
Xian Cheng Zhang
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Diffraction Method ◽  
Relaxation Rates ◽  
Deep Rolling ◽  
Fatigue Process ◽  
Compressive Residual Stresses

Compressive residual stresses have been found to affect fatigue crack growth behavior by delaying the crack initiation and by decelerating the crack propagation rate. Therefore, various mechanical surface treatment techniques have been developed to produce the compressive residual stresses on the surface of components. However, the residual stresses will relax due to cyclic loading. Hence, the stability of residual stress during fatigue process is a great importance aspect for design of components. In this paper, the ultrasonic surface deep rolling was used to generate the compressive residual stress near the surface of Ti-6Al-4V. The stress relaxation behavior was identified during the low cycle fatigue process. The X-ray diffraction method was used to determine the magnitude and sign of residual stress. Results showed that under cyclic loading, the residual stress relaxation occurred fast in the first few cycles then became stable. Furthermore, it was found that relaxation rates of residual stress were depended on the applied stress.

Residual Stress Relaxation and Microstructure in ZnO Thin Films

2006 ◽  
Vol 45 ◽  
pp. 1316-1321 ◽  
Author(s):  
Istem Ozen ◽  
Mehmet Ali Gülgün
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Residual Stresses ◽  
Thermal Annealing ◽  
Structural Damage ◽  
Single Crystal Silicon ◽  
Extended Period ◽  
Zno Thin Films ◽  
Zno Films ◽  
Crystal Silicon

Stability under normal environmental conditions over a long period of time is crucial for sustainable thin-film device performance. Pure ZnO films with thicknesses in the 140 - 450 nm range were deposited on amorphous glass microscope slides and (100)-oriented single crystal silicon wafers by radio frequency magnetron sputtering. The depositions were performed at a starting temperature of 200 oC. ZnO films had a columnar microstructure strongly textured along the <0002> direction. XRD peak-shift analysis revealed that the films were under residual, compressive, in-plane stress of -5.46 GPa for the glass substrate and -6.69 GPa for the Si substrate. These residual stresses could be completely relaxed by thermal annealing in air. When left under normal environmental condition over an extended period of time the films failed under buckling leading to extensive cracking of the films. The XRD and SEM results indicated different mechanisms of stress relaxation that were favored in the ZnO thin films depending on the energy provided. Although thermal annealing eliminated residual stresses, serious micro-structural damage upon annealing was observed. Thermal annealing also led to preferential growth of some ZnO crystals in the films. This kind of behavior is believed to be indicative of stress-induced directional diffusion of ZnO. It appears that for the extended stability of the films, the stresses have to be eliminated during deposition.

Retained Austenite and Residual Stress Evolution in Carbonitrided Shot-Peened Steel

2011 ◽  
Vol 681 ◽  
pp. 374-380 ◽  
Author(s):  
S. Van Wijk ◽  
Manuel François ◽  
E. Sura ◽  
M. Frabolot
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Shot Peening ◽  
Industrial Process ◽  
High Hardness ◽  
Residual Austenite ◽  
Stress Evolution ◽  
X Ray Diffraction ◽  
Austenite Transformation ◽  
Compressive Residual Stresses

Carbonitriding followed by shot peening is an important industrial process to improve the mechanical properties of components, especially by producing compressive residual stresses. In addition, a high hardness and strength produced by this process enhances the surface properties and leads also a high resistance to fatigue. In this study, shot peening with different parameters have been employed to treat the carbonitrided specimens. The measurements of residual stress and residual austenite were performed by X-ray diffraction. It is shown, with a simple eigenstrain model, that residual austenite transformation under shot impact contributes to a significant fraction of residual stresses. When the material (750 HV) is peened with 800 HV shot, it represents about 50%, the remaining is due to plasticity. When it is peened with 640HV shot, 100% of residual stresses can be explained by austenite transformation.

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