Silicon wafer and method for production of silicon wafer

Abstract

A silicon wafer, which has been doped with nitrogen and has been subjected to an extrinsic gettering (EG) treatment, for example, the formation of a polysilicon layer. In the silicon wafer, when the wafer is exposed to an ion of a heavy metal such as copper or nickel in a device manufacturing process, the copper and nickel can be captured by the action of intrinsic gettering (IG) in the course of a heat treatment, and, when a polysilicon layer is formed as a strain layer, iron and copper can be captured by the action of an extrinsic gettering (EG) using the polysilicon as a strong point for the capture.

Description

TECHNOLOGICAL FIELD [0001] The present invention relates to a silicon wafer and a method for manufacturing a silicon wafer. More particularly, the present invention relates to a silicon wafer, which is capable of preventing a contamination of heavy metal ions therein, and a manufacturing method thereof. Background Art [0002] Semiconductor devices are typically manufactured via a device manufacturing process for forming device layers on the surface of the silicon wafer by a thin film, diffusion or the like. [0003]FIG. 3 is a cross sectional view of a silicon wafer 1′ in which an epitaxial growth layer 2 is formed on a silicon wafer substrate 1, assuming that the wafer is a silicon (Si) wafer. [0004] The silicon wafer 1′ is doped with boron B as an impurity (dopant). The silicon wafer 1′ is a p / p− silicon wafer doped with the impurity B of relatively low concentration. Inside the furnace of an epitaxial growth apparatus, feed gases for a thin film such as trichlorosilane (SiHCl3) is s...

AI Technical Summary

Benefits of technology

[0025] In view of the above situation, the present invention provides a solution to the above-mentioned problem, and it is an object of the present invention to provide a technology for improving the gettering ability of heavy metal ions.

[0036] According to the present invention, as shown in FIG. 1, the silicon wafer 1′ is subjected to a nitrogen doping process, the nitrogen being as an element of facilitating BMD precipitation, and also subjected to an extrinsic gettering (EG) treatment, for example, a process of forming a polysilicon layer 3. Therefore, even if the silicon wafer is exposed to heavy metal ions such as copper, nickel or the like during the device manufacturing process, the intrinsic gettering (IG) acts during the the heat treatment, and thus copper and nickel can be captured (see FIG. 2). In addition, since the polysilicon layer 3 is formed as a strain layer, iron and copper can be captured using the polysilicon layer 3 as a strong point for the capture with the action of the extrinsic gettering (EG)(see FIG. 2). Thus, according to the present invention, sufficient gettering of various heavy metal ions such as iron, copper, nickel or the like generated during the device manufacturing process, can be achieved. Therefore, migrations of heavy metal ions such as iron, copper, nickel or the like into the device layer of the silicon wafer 1′ can be avoided, thereby to prevent malfunctions of the device, and to effect a longer product life.

Problems solved by technology

When heavy metal ions such as iron ions or the like are migrated into the device layer of the silicon wafer 1′ during the device manufacturing process, the resultant devices may possibly perform false operations, and as a result may have a short life.

In addition, since higher concentration of boron as dopant results in higher concentration of BMD, the concentration of the BMD in the p / p− silicon wafer 1′ doped with boron of a low concentration is decreased, thereby reducing the gettering ability thereof.

As such, the silicon wafer 1′ doped with boron of a low concentration and having an epitaxial growth film 2 formed thereon has a problem of lower gettering ability.

However, this attempt has a problem that the heat treatment requires a long time, and thus the manufacturing cost of silicon wafer is increased.

On the other hand, since the above-mentioned steps (a) to (c) should be carried out for performing the EG treatment on the silicon wafer 1′, the steps for manufacturing the wafers become complicated, thereby requiring longer time, and thus the manufacturing cost is increased.

However, the situation of insufficient gettering ability has arisen in both the IG that additionally includes the nitrogen doping process and the EG treatment.

This problem has not been solved in the existing circumstances.

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