A method for manufacturing a silicon epitaxial wafer of a high-power pin device

Abstract

The invention provides a manufacturing method of a silicon epitaxial wafer of a large-power PIN device. The method is that a highly As-doped N type <100> polished wafer of which the resistivity does not exceeds 0.003 ohm / cm and local flatness does not exceeds 1.5mm and the rear surface is free of a back seal oxide layer is adopted. The manufacturing method of the silicon epitaxial wafer of the large-power PIN device has the advantages that 1, polycrystalline silicon is transferred from a graphite base to the rear surface of a substrate by the mass transfer principle, so as to reach the back enveloping purpose; 2, proper atmospheric corrosion flow and atmospheric corrosion time are selected and the gas phase concentration of atmospheric corrosion impurities in an epitaxial reaction chamber is reduced so as to reduce self doping under epitaxial growth; 3, after atmospheric corrosion, variable temperature and flow hydrogen is selected to purge the epitaxial reaction chamber; 4, during the growth of a first epitaxial layer, an intrinsic epitaxial layer grows under relatively low temperature to envelope the high-concentration substrate surface, and the growth temperature, rate and time are controlled to reach an ideal enveloping layer; and 5, during the growth of a second epitaxial layer, an epitaxial layer of which the surface concentration is below 10E13cm-3 grows under a low temperature.

Description

technical field [0001] The invention relates to a silicon epitaxial wafer in the field of semiconductor silicon materials, in particular to a method for manufacturing a silicon epitaxial wafer of a high-power PIN device. Background technique [0002] PIN diode (positive-intrinsic-negative diode, abbreviated as PIN diode) is a kind of light that absorbs light radiation and generates photocurrent in the PN junction between two semiconductors, or in the vicinity of the junction between semiconductor and metal. Detector. Ordinary diodes are composed of PN junctions, and a thin layer of low-doped intrinsic (Intrinsic) semiconductor layer is added between P and N semiconductor materials. The diode of this P-I-N structure is a PIN device. PIN device is a common semiconductor device widely used in the fields of microwave, electric power and optoelectronics. It is mostly used as microwave switch, microwave attenuator, microwave limiter, digital phase shifter, etc. High-power rectif...

AI Technical Summary

Problems solved by technology

However, in the actual growth process, due to the solid-state diffusion of impurity atoms from the high-concentration substrate to the epitaxial layer and HCl corrosion before epitaxy, H 2 The high temperature during processing and epitaxial growth causes the impurity atoms of the heavily doped substrate to evaporate from the solid phase to the gas phase of the reaction chamber from the front, edge and back. Although blown off by a large flow of gas, some impurities still remain on the substrate. In the stagnant layer on the surface, it enters the epitaxial layer during epitaxial growth to form gas-phase self-doping, which causes the impurity concentration at the interface between the substrate and the epitaxial layer to be too high, causing the transition zone to widen, thereby reducing the effective thickness of the epitaxial layer

At the same time, gas-phase self-doping has a great influence on the uniformity of radial resistivity distribution on the surface of the epitaxial layer, so that the center resistivity of the epitaxial wafer is high and the edge resistivity is low. When the device is made, its breakdown voltage Vbc is large in the middle and small at the edge. , resulting in uneven breakdown voltage and series resistance