硅片氧含量径向不均匀性问题

经多方面检测分析，证明硅片中原始氧含量的径向不均匀度是影响硅片高温过程中的几何稳定性和单片电路成品率的重要因素。

区熔气相掺杂硅单晶径向电阻率均匀性的研究

本文通过试验研究了下轴转速、正反转时间比、偏心度三个方面因素对于区熔气相掺杂硅单晶径向电阻率均匀性的影响。试验结果表明:随着下轴转速的不断增加,单晶径向电阻率分布偏差呈先降低后升高的趋势;正反转时间比增加,单晶径向电阻率分布得到明显改善,正反转角度进一步增加,径向电阻率分布偏差又有升高的趋势;随偏心度增加,单晶边缘与中心点电阻率趋于一致,单晶径向电阻率不均匀性明显减小。

高阻区熔硅单晶的径向少子寿命变化

在氩气气氛及真空环境下生长的高阻区熔硅单晶的径向少子寿命分布情况进行了检测。检测结果表明,在氩气气氛下生长的各种规格的高阻单晶,其少子寿命一般都在1 000μs以上,且径向变化大部分在10%以内,当生长工艺参数改变时,单晶少子寿命的径向分布规律虽然会有所不同,但对少子寿命径向均匀性的影响却几乎可以忽略。而在真空环境、不同工艺参数下生长的单晶,其少子寿命的径向分布及均匀性的变化则十分的明显,还会经常看到中心少子寿命400~500μs、边缘区域少子寿命高于1 000μs的单晶。本文在单晶生长试验的基础上,通过对产生这种现象的原因进行分析,确定了采用适当地降低晶体生长速率、提高加热功率的方法,可以使高阻真空区熔硅单晶中心区域的少子寿命的提高,并使其径向分布变均匀。

Influence of radial forging process on strain inhomogeneity of hollow gear shaft using finite element method and orthogonal design

Due to the current trend towards lightweight design in automotive industry,hollow stepped gear shafts for automobile and its radial forging process are widely investigated.Utilizing coupled finite element thermo-mechanical model,radial forging process of a hollow stepped gear shaft for automobile was simulated.The optimal combination of three process parameters including initial temperature,rotation rate and radial reduction was also selected using orthogonal design method.To examine the strain inhomogeneity of the forging workpiece,the strain inhomogeneity factor was introduced.The results reveal that the maximum effective strain and the minimum effective strain appeared in the outermost and innermost zones of different cross sections for the hollow stepped gear shaft,respectively.Optimal forging parameters are determined as a combination of initial temperature of 780°C,rotation rate of 21°/stroke and radial reduction of 3 mm.