Production method of heavily phosphorus-doped thin substrate silicon epitaxial layer for Schottky devices

Abstract

The invention relates to a production method of a heavily phosphorus-doped thin substrate silicon epitaxial layer for Schottky devices. The method adopts a normal-pressure flat plate type epitaxial furnace, and comprises the following steps: 1, polishing the pedestal of the epitaxial furnace at a high temperature by using hydrogen chloride with the purity being not lower than 99.99%; 2, filling the epitaxial furnace with a phosphorus-doped silicon substrate slice, and sequentially purging the cavity of the epitaxial furnace by nitrogen and hydrogen, wherein the purities of nitrogen and hydrogen are not lower than 99.999% respectively; 3, polishing the surface of the silicon substrate slice by using a hydrogen chloride gas; 4, purging the surface of the silicon substrate slice by using a bulk flow of hydrogen; 5, growing an intrinsic epitaxial layer; 6, carrying out variable flow purging on the reaction cavity of the epitaxial furnace; and 7, growing a doped epitaxial layer. The thickness inhomogeneity of the epitaxial layer is smaller than 1%, the resistivity inhomogeneity of the epitaxial layer is smaller than 1%, the surface of the epitaxial layer has no stacking fault, dislocation, slip lines, mist or other defects, the width of a transition region under optimum conditions can be smaller than 1[mu]m, and requirements of the silicon epitaxial layer by the Schottky devices can be completely met, so the performances and the yield of the Schottky devices are improved.

Description

technical field [0001] The invention relates to a preparation technology of a silicon epitaxial layer for a Schottky device, in particular to a preparation method for a silicon epitaxial layer on a heavily doped thin phosphorus substrate for a Schottky device. Background technique [0002] Schottky devices are low-power, high-current, ultra-high-speed semiconductor devices. Key devices such as breakdown voltage and forward voltage drop basically depend on the parameters of the epitaxial layer substrate, especially high-performance silicon Schottky diodes. The quality of the epitaxial layer has higher requirements, such as better uniformity, narrow transition zone, and low defect density. At present, the epitaxial layer on the heavily doped phosphorus substrate is the first choice for Schottky devices, which can greatly reduce the forward voltage drop and reduce the power consumption of the device. The bottom (resistivity 0.002~0.004W×cm), due to the higher doping concen...

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Problems solved by technology

But at the same time, due to the difference in the thickness of the substrate, the distribution of the flow field in the epitaxial cavity will inevitably be different, which increases the difficulty of thickness uniformity control

Moreover, substrates with different thicknesses need to experience different thermal stresses during the epitaxial growth process, which greatly increases the difficulty of controlling epitaxial defects.

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