Method for manufacturing a silicon wafer

Abstract

Method for manufacturing a silicon wafer free of point defect agglomerates by processes including adding pure carbon to raw material of polycrystalline silicon, melting to become a molten silicon liquid, pulling a single silicon crystal ingot comprising a perfect domain [P] from the molten silicon liquid by controlling a ratio of V / G (mm2 / minute ° C.), lapping a silicon wafer cut out from the ingot, beveling the silicon wafer, chemical etching the beveled wafer so as to be removed damages of a surface of the wafer, and mirror-polishing the etched wafer, and the pure carbon is added to the raw material of polycrystalline silicon so that a density of carbon in the ingot becomes 1×1015 to 5×1015 atoms / cm3.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of application Ser. No. 09 / 718,659, filed Nov. 22, 2000, the disclosure of which is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a silicon wafer made of a single crystal silicon ingot grown by the Czochralski method (hereinafter, referred to as CZ method) and a method for manufacturing the same wafer. And it relates more particularly to a silicon wafer to be used for manufacturing a semiconductor device such as an LSI and the like.[0004]2. Description of the Related Art[0005]A semiconductor device such as an LSI and the like needs to exhibit such excellent electric characteristics that a leakage current is a little in a pn junction and an MOS transistor has a high reliability in a gate oxide film. Crystal defects in a silicon wafer to be a substrate and contamination caused by a metal element in the wafer...

AI Technical Summary

Benefits of technology

[0015]A first object of the present invention is to provide a silicon wafer which does not have defects caused by crystal and which is low in the contamination degree by metal such as iron and excellent in electric characteristics, and provide a method for manufacturing the same.

[0016]A second object of the present invention is to provide a silicon wafer which has little agglomerates of point defects even if an ingot is pulled at a comparatively high speed and at a V / G value within a wide range, makes it possible to manufacture a semiconductor integrated circuit at a high yield rate and can be compatible with an existing device process thanks to its resistivity of 1 to 15 Ωcm and to provide a method for manufacturing the same.

[0017]A third object of the present invention is to provide a silicon wafer which can be adjusted so as to have a desired resistivity and a method for manufacturing the same.

Problems solved by technology

Above all among metal elements in a single crystal silicon, an iron element is thought to have a bad influence and this iron element is taken in by contamination from an environment or an apparatus.

In case that a large amount of metal element is mixed into a single crystal silicon ingot grown by the CZ method, however, it is necessary to more and more complicate or advance a technique for removing or capturing the metal element from a silicon wafer.

The OSF is made by a fact that a microscopic defect to be the nucleus of a crystal is introduced when growing the crystal, is actualized in a thermal oxidation process and the like when manufacturing a semiconductor device, and causes a failure such as the increase of leakage current in a manufactured device.

And existence of COPs on the surface of a wafer makes a step in a wiring process of a device and can cause breaking of wire.

And it may cause leakage and the like in an isolation part of a device and reduces the yield rate of a product.

When a wafer having an insufficient gettering ability is contaminated by metal in a device process, a defective operation of a device is caused by a junction leakage or a trap state by a metal impurity and thereby the yield rate of the product is lowered.

However, in a wafer being comparatively low in vacancy point defect density among silicon wafers composed of said perfect domain [P], oxygen precipitation does not always occur uniformly in the wafer in heat treatment in a device process and thereby the wafer sometimes cannot obtain a sufficient gettering effect.

And in case that the temperature gradient is constant, the value of V / G for producing a silicon wafer composed of a perfect domain [P] is in proportion to the pulling speed V of an ingot and it is required to pull the ingot at a comparatively low speed controlled within a narrow range, but it is not always technically easy to meet securely this requirement and the productivity of such an ingot also is not high.

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