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用示踪原子方法,研究了磷(Na_2HP~(32)O_4)在p型硅表面氧化层中的扩散。硅单晶的电阻率为5—6欧姆·厘米。氧化层是在高温下水汽中生长的,其厚度为0.5—0.6微米,是用灵敏度为10~(-5)克/刻度的微量天平测定的。发现在1245℃时氧化层的生长规律服从X~(1.85)=1.4×10~(-2)t,其中X为氧化层的厚度,单位为微米;t为氧化层的生长时间,单位为分钟。其红外吸收的测量结果与文献中的数据基本一致。扩散是在充满空气的封闭石英管中进行的,扩散温度为700—1250℃,扩散时间从4分钟到5小时。实验结果表明,磷在SiO_2层中的浓度分布不能直接用菲克第二定律描述,它可以看成是一个均匀分布和一个遵守菲克第二定律的分布的迭加。按后一种分布得到在700—1200℃范围内的扩散系数的温度依赖关系:D=1.9×10~(-9)exp(-1.1/kT)厘米~2/秒。均匀分布部分的浓度为(1—8)×10~(19)原子/厘米~3。大中对所用方法和所得结果作了简单讨论.
The diffusion of phosphorus (Na_2HP ~ (32) O_4) in the oxide layer on the surface of p-type silicon was studied by tracer atom method. The resistivity of the silicon single crystal is 5-6 ohm.cm. The oxide layer is grown at high temperatures under water vapor and has a thickness of 0.5-0.6 microns as measured by a microbalance with a sensitivity of 10-5 grams per micrometer. It was found that the growth law of the oxide layer at 1245 ℃ obeys X ~ (1.85) = 1.4 × 10 ~ (-2) t, where X is the thickness of the oxide layer in micrometers; t is the growth time of the oxide layer in minutes . The infrared absorption measurement results and the literature data are basically the same. The diffusion is carried out in an air-filled, closed quartz tube with a diffusion temperature of 700-1250 ° C and a diffusion time of 4 minutes to 5 hours. The experimental results show that the concentration distribution of phosphorus in the SiO 2 layer can not be directly described by Fick’s second law. It can be regarded as a uniform distribution and a superposition of the distribution according to Fick’s second law. The latter distribution gives the temperature dependency of the diffusion coefficient in the range of 700-1200 ° C: D = 1.9 × 10 -9 exp -1.1 / kT cm -2 / sec. The concentration of the uniformly distributed portion is (1-8) × 10-19 atoms / cm3. Dazhong made a brief discussion of the methods used and the results obtained.