A method for the production of p - doped zones with different penetration depths in a n - silicon - layer

摘要

1,232,727. Semi-conductor device. SIEMENS A.G. 26 Nov., 1969 [27 Nov., 1968], No. 57766/69. Heading H1K. A p-type zone of varied depth in an n-type zone of a silicon crystal is made by diffusing boron into the n-type zone and thereby forming a layer of boron oxide glass on a surface of the crystal, heating the crystal in a moist atmosphere, removing areas of the boron oxide glass photolithographically using a photovarnish mask and heating the crystal to 900‹ to 1300‹ C. whereby the portions of the p-type zone beneath the residual parts of the glass are diffused further into the crystal. A p-type silicon body 1 has an epitaxial n-type layer 2 grown thereon and a boron-oxide glass layer (3, Fig. 2, not shown) is grown thereon by a transport reaction with B 2 O 3 as a source in a stream of Ar or N 2 or with B 2 H 6 . A p-type zone (4) is formed by diffusion of boron into the epitaxial layer 2. The body is heated in a moist atmosphere to make the glass more readily etchable, a photoresist mask applied and the exposed glass portions etched away 15 using HF+NH 4 F. The body is heated again to diffuse boron from the remaining glass portions 13 further into the n-type layer 12. Optionally a further oxide layer may be formed over the boron oxide layer prior to heating in a moist atmosphere by pyrolysis of tetraethoxysilane. The device formed is a junction-gate FET and may comprise one of many in an integrated circuit.