Unpolished Semiconductor Wafer and Method For Producing An Unpolished Semiconductor Wafer

Abstract

Unpolished semiconductor wafers are produced by: (a) pulling a single crystal of a semiconductor material, (b) grinding the single crystal round, (c) separating a semiconductor wafer from this crystal, (d) rounding the edge of the semiconductor wafer, (e) surface-grinding at least one side of the semiconductor wafer, (f) treating the semiconductor wafer with an etchant, and (g) cleaning the semiconductor wafer. The unpolished semiconductor wafers have, on at least the front side, a reflectivity of 95% or more, a surface roughness of 3 nm or less, have a thickness of 80-2500 μm, an overall planarity value GBIR of 5 μm or less with an edge exclusion of 3 mm and a photolithographic resolution of at least 0.8 μm, and which furthermore contain a native oxide layer with a thickness of 0.5-3 nm on both sides.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to an unpolished semiconductor wafer and to a method for producing an unpolished semiconductor wafer.[0003]2. Background Art[0004]According to the prior art, semiconductor wafers are produced in a multiplicity of successive process steps, which can generally be subdivided as follows:[0005]a) production of a single crystal of semiconductor material (crystal pulling);[0006]b) separation of the semiconductor single crystal into individual wafers (wafering, sawing);[0007]c) mechanical processing of the semiconductor wafers;[0008]d) chemical processing of the semiconductor wafers;[0009]e) chemical-mechanical processing of the semiconductor wafers.Added to this, there are a multiplicity of substeps such as cleaning, measuring and packaging.[0010]A single crystal is conventionally produced by pulling a semiconductor single crystal from a melt (CZ or Czochralski method) or by recrystallizing a rod of polyc...

AI Technical Summary

Benefits of technology

[0032]It is therefore an object of the invention to improve the surface quality of unpolished semiconductor wafers and to permit smaller linewidths of components produced thereon. These and other objects are achieved by a method for producing an unpolished semiconductor wafer which comprises the following steps: (a) pulling a single crystal of a semiconductor material, (b) grinding the single crystal round, (c) separating a semiconductor wafer from this crystal, (d) rounding the edge of the semiconductor wafer, (e) surface-grinding at least one side of the semiconductor wafer, (f) treating the semiconductor wafer with an etchant, (g) finally cleaning the semiconductor wafer. The wafers thus produced are not processed further, but are packaged for shipping.

Problems solved by technology

For the production of semiconductor wafers for applications in power electronics or for the fabrication of discrete components, however, these methods are too elaborate and uneconomical.

A disadvantage of this method is that lapping leads to damage deep into the interior of the crystal lattice, which usually necessitates increased material removal during the subsequent etching in order to remove this damage.

A high etch removal leads to a deterioration of the planarity of the semiconductor wafer.

This method is also disadvantageous, since further deterioration of the planarity of the semiconductor wafer is to be expected from two etching steps.

An inferior surface roughness of the semiconductor wafers produced, namely less than 100 nm, is reported in all known methods in which a lapping step is provided.

Another disadvantage of the foregoing method is that again, a high etching removal is provided, which entails a deterioration of the planarity or the microstructure of the surface of the wafer.

Such a microstructure leads to a limitation of the possible linewidth in photolithographic processes during the production of components.