Formation of Shallow P-N Junction in Silicon Wafer by Solid-Phase Diffusion at Low-Temperatures.

本文研究了低温条件下在硅片上形成pn结的方法。利用光辐射加热硅时杂质（磷和硼）的扩散增强，可以在低温下形成pn结。重要结果如下：1。在卤素灯或氙灯的光照射下加热硅时，杂质的扩散大大增强。在这种条件下，杂质的扩散系数比通常的电炉加热方式大100-300倍。利用光辐射加热时的增强扩散，可以在540℃的温度下将杂质扩散到硅中。用这种方法制成的pn结二极管在低温下具有良好的电学特性。经过这种强化扩散后，硅片上没有发现缺陷。因此，本文所提出的在低温下掺杂杂质的方法对器件的制作是有用的。（100）取向硅片的扩散增强幅度大于（111）取向硅片。磷和硼的扩散增强明显，而砷的扩散没有增强。7.光照射时扩散增强是由于硅片中产生了过量的自间隙，这些自间隙可能在光照射时从扩散源膜与硅片之间的界面注入硅片中。对增强扩散和低温扩散有效的光波长为0.6 ~ 1.0 μ m。

In the present work, it has been investigated to form pn junction in silicon wafer at low-temperatures. The pn junction can be formed at low-temperatures by using the enhanced diffusion of impurities (phosphorus and boron ) during heating of silicon with light irradiation. The important results are as follows.1. The diffusion of impurities during heating of silicon with light irradiation from a halogen lamp or a xenon lamp is enhanced considerably. The diffusion coefficients of impurities in such conditions are 100-300 times larger than those during usual heating method by furnace.2. It is possible to diffuse impurities into silicon at 540ﾟC by using the enhanced diffusion during heating with light irradiation.3. The pn junction diode made by such method at low-temperatures indicates a good electrical characteristics.4. After such enhanced diffusion, no defects are found in the silicon wafer. Therefore, it is concluded that the present method for doping of impurities at low-temperatures is useful to device fabrication.5. The enhanced diffusion in (100)-oriented silicon wafer is larger than that in (111) wafer. While phosphorus and boron show a great enhanced diffusion, arsenic shows no enhanced diffusion.6. The enhanced diffusion during light irradiation is due to generation of the excess self-interstitials in silicon wafer, which may be injected into silicon wafer from the interface between the diffusion source film and the silicon wafer during light irradiation.7. The wavelength of light which is effective for the enhanced diffusion and the diffusion at low-temperatures is 0.6-1.0 mum.