| 摘要 |
<p>1379975 Semi-conductor devices PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 28 Jan 1972 [2 Feb 1971] 4123/72 Heading H1K In manufacturing a PN junction semiconductor capacitor a first layer 2 of the same conductivity type as, but of lower conductivity than, a substrate 1 is deposited on the substrate 1, at least a second layer 3 of the same conductivity type as, but higher conductivity than, the layer 2 is deposited thereon. The conductivity of a surface portion of the layer 3 is increased by diffusing in further impurity of the same conductivity type and finally the PN junction 13 is formed by diffusing in an impurity of the opposite type. During the first-mentioned diffusion and any other heating stage employed, e.g. to form an oxide coating on the layer 2, the steplike impurity profile resulting from the sharp boundaries between the substrate 1 and the layers 2 and 3 is rounded off by thermal diffusion. More than two layers may be provided, each layer having a higher conductivity than the layer on which it is deposited. More than one impurity may be diffused simultaneously into the layer 3 to obtain a desired profile. In an example in which an Sb-doped Si substrate 1 has formed thereon P-doped epitaxial layers 2 and 3, P and Sb or As are simultaneously diffused into the layer 3, the former impurity having the lower surface concentration but the greater depth of penetration into the layer 3. The PN junction 13 is finally formed by means of a B-diffusion stage.</p> |
