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当砷相继地扩散入掺镓或掺硼的硅中时,通常观察到 P 型基区层扩散的减慢。这与相继的磷扩散有关连的“发射极推进”效应是相反的。为了模拟晶体管中的杂质分布,必须能够定量地描述在扩散过程中发射区——基区的相互作用。在这研究中考查了关于内部电场,平衡空位密度,离子对以及〔VsiAs_2〕络合物形成的速率对于相继地扩散过程中的基区层再分布的影响。对于一对扩散方程的数字解表明,在砷发射极的扩散时,电场和离子对的效应只引起硼分布的局部减慢。然而,〔VsiAs_2〕络合物的形成引起在硅中空位的不饱和达到晶体内刚好超过实际的集电极——基极结深的距离。因为局部的基区扩散率依赖于空位密度,所以这种非本征的空位不饱和的效应引起所予期的基区扩散的减慢。根据发射区和基区的表面浓度、初始的基区结深以及扩散时间和温度的关系,给出了该理论正确性的实验验证。
As arsenic successively diffuses into gallium-doped or boron-doped silicon, diffusion of the p-type base layer is usually observed to slow down. This is the opposite of the “emitter propulsion” effect associated with successive phosphorous dispersions. In order to simulate the impurity distribution in a transistor, it is necessary to be able to quantitatively describe the emitter-base interaction during diffusion. In this study, we examined the effect of internal electric field, equilibrium vacancy density, ion pairs and rate of formation of [VsiAs_2] complexes on the basement layer redistribution during successive diffusion processes. The numerical solution to a pair of diffusion equations shows that the effect of the electric field and the ion pair causes only a partial slowdown of the boron distribution at the diffusion of the arsenic emitter. However, the formation of the [VsiAs_2] complex causes the unsaturation in the vacancy in the silicon to reach within the crystal just beyond the actual collector-base junction depth. Because the local basal zone diffusion rate depends on the vacancy density, the effect of this extrinsic vacancy unsaturation causes a slowdown of the given base zone diffusion. According to the surface concentration of emitter region and base region, the initial junction depth of base region and the relationship between diffusion time and temperature, experimental verification of the theoretical correctness is given.