The effect of stress in silicon nitride films on boron diffusion of silicon has been studied. During annealing in nitrogen, the degree of the retardation in boron diffusion becomes larger as the temperature becomes lower and the thickness of nitride films increases. On the other hand, boron diffusion of Si covered with very thin nitride films is enhanced for long diffusion times. These results suggest that nitride film stress makes the region near the surface of the silicon substrate compressed and changes vacancy and interstitial concentrations.The various thin films used in LSI usually develop stress during the thermal process and the stress causes problems such as leak current and generation of dislocations in large scale integrated (LSI) devices. Moreover, accurate control of boron diffusion %vith doses of 1012 to 1013/cm 2 in silicon covered with various films is essential for channel doping with the scaling down of LSI. Therefore, it is necessary to investigate the effects of stress in the films on the substrate and on dopant diffusion in the silicon substrate.Silicon nitride (Si3N4) films used as oxidation resistant masks and dielectric layers are highly stressed, 1-4 so the effect of stress in the Si3N4 films on dopant diffusion is of interest. With respect to this topic, Mizuo et al. ~ and Ahn et al.6 reported that diffusion of dopant in float zone (FZ) silicon under Si3N4 films was retarded compared with that under silicon dioxide (SiO2) films covered with nitride films. However, Mizuo et aI. did not take into account the effect of stress in deposited Si~N~ films during heat-treatment. Since Ahn et al. deposited off-stoiehiometrie Si3N4films on both sides of the samples to prevent bending of the substrates, it seems that they investigated the effect of the chemical reaction between off-stoiehiometric nitride films and the surface of the Si substrate on the diffusion of phosphorus in FZ-Si, but not on the stress in SiaN4 films. Their experimental conditions ~' 6 were also restricted in terms of the thickness of Si3N 4 films, time, and temperature of diffusion. Moreover, their analysis based on only the penetration depth monitored by a staining technique was not sufficient.In the present paper, we have investigated the effect of stress in deposited Si3N~ films on the diffusion of boron in FZ-Si. The thickness of Si3N4 films, time, and temperature of diffusion were varied in a wide range. In addition to the Si3N4/Si structure, boron diffusion of Si under the area masked with double-layered SiO2-Si3N4 films and the area without any films was also performed to clarify the effect of SigN4 film stress on the point defect generation. Boron profiles were measured by secondary ion mass spectroscopy (SIMS). We found that diffusion of boron in FZ-Si under Si3N, films had anomalous characteristics. These results are discussed in terms of point defect concentration. ExperimentalThe substrates used were p-type (100) FZ-Si wafers with resistivities of 3 to 5 f~-em. The use of FZ-Si is essential for avoiding the accompa...
The effect of stress during annealing induced by Si3N4 films on boron diffusion in float zone-silicon has been studied and a correlation between vacancy concentration and compressive strain in the substrate has been clarified. From the results of Si3N4 film thickness and annealing temperature dependence on both boron diffusivity and stress in the substrates, boron diffusion was found to be retarded and the substrate was found to have high stress, having elastic compressive strain during annealing under Si3N4 films. These results indicate that excess vacancies are generated by elastic compressive strain, causing the retardation of interstitial-mediated diffusion of boron.
PurposeThe Stump classification is significantly correlated with a retear after arthroscopic rotator cuff repair. However, no study has evaluated whether or not the stump classification is correlated with retear in the suture‐bridge or double‐row repair techniques. The aim of this study was to evaluate the relationship between a retear and the stump classification in the suture‐bridge and double‐row repair techniques. MethodsAmong 389 patients who underwent arthroscopic repairs of full‐thickness rotator cuff tears using suture‐bridge or double‐row repair techniques, 326 patients (median age 67.0 years; range 25–85) were included. There were 51 small, 172 medium, 83 large, and 20 massive tears. Two hundred forty patients were treated with the suture‐bridge technique, and 86 patients were treated with the double‐row technique. The following variables were analyzed: age, sex, the Cofield classification, anteroposterior and mediolateral tear size on preoperative MRI, global fatty degeneration index, and the stump classification. Cuff integrity was evaluated on magnetic resonance imaging at 6 months after surgery. The patients were divided into the intact and retear groups and the relationship between the variables and retear was evaluated by multivariate logistic regression analysis. ResultsThe overall retear rate was 10.1%. In the multivariate logistic regression analysis, the independent predictors of a retear were the stump classification type 3 (Odds ratio: 4.71, p = 0.0246), global fatty degeneration index (Odds ratio: 3.87, p = 0.0030), and anteroposterior tear size (Odds ratio: 1.07, p = 0.0077) in the suture bridge technique. In the double‐row technique, the independent predictors of retear were stump classification type 3 (Odds ratio: 7.82, p = 0.0348), and age (Odds ratio: 1.22, p = 0.0163). ConclusionThe stump classification was significantly correlated with retear in the suture‐bridge and double‐row repair technique. Stump classification type 3 was indicated to be an important risk factor for predicting retear. Level of evidenceIII
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