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Process for metallic contamination reduction in silicon wafers

A technology of silicon wafers and impurities, applied in the field of semiconductor material substrates, can solve problems such as limitations, increased wafer costs, and reduced yields

Inactive Publication Date: 2007-06-13
MEMC ELECTONIC MATERIALS INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although these low-temperature annealing operations can be used to effectively remove copper from individual silicon wafers, they are not done in typical manufacturing methods because they would greatly reduce yield and greatly increase the cost of the wafer
Therefore, these low temperature annealing operations are limited to laboratory and pilot applications

Method used

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  • Process for metallic contamination reduction in silicon wafers

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Embodiment Construction

[0015] The following discussion focuses on copper impurities in silicon; copper is the most studied and is usually the biggest problem among metallic impurities. However, the methods described here for copper are also applicable to other metallic impurities found in silicon (eg, nickel, iron, aluminum, chromium, etc.).

[0016] Without being bound to any particular theory, the copper is thought to form some sort of complex with boron and in this way be bound or "stored" in the boron-doped silicon wafer. In addition, these copper-boron complexes are also believed to be metastable even at room temperature. Thus, over time, these complexes dissociate, leaving the copper in interstitial positions. Copper is a fast diffuser in silicon; the fastest of all metals and very active even at room temperature. However, the solubility of copper in silicon is very temperature dependent and very low at low temperatures such as room temperature. Therefore, at low temperatures, interstitial ...

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Abstract

A process for removing a contaminant selected from among copper, nickel, and a combination thereof from a silicon wafer having a surface and an interior. The process comprises cooling the silicon wafer in a controlled atmosphere from a temperature at or above an oxidation initiation temperature and initiating a flow of an oxygen-containing atmosphere at said oxidation initiation temperature to create an oxidizing ambient around the silicon wafer surface to form an oxide layer on the silicon wafer surface and a strain layer at an interface between the oxide layer and the silicon wafer interior. The cooling of the wafer is also controlled to permit diffusion of atoms of the contaminant from the silicon wafer interior to the strain layer. Then the silicon wafer is then cleaned to remove the oxide layer and the strain layer, thereby removing said contaminant having diffused to the strain layer.

Description

technical field [0001] The present invention generally relates to the preparation of substrates of semiconductor material, especially silicon wafers, for the manufacture of electronic components. More specifically, the present invention relates to methods for thermally treating or annealing one or more silicon wafers to reduce the concentration of metallic impurities, such as copper, from within or in the bulk of the wafer. Additionally, performing the method of the present invention may reduce the concentration or size of accumulated vacancy defects on the surface and in the volume of one or more silicon wafers. Background technique [0002] Silicon device performance degrades due to metal impurities. Transition metals - including copper, iron, and nickel - can dissolve and diffuse during routine thermal cycling associated with integrated circuit fabrication conditions. When cooling from the temperatures associated with the fabrication of integrated circuits, copper and o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L21/322H01L21/324
CPCH01L21/3221H01L21/324H01L21/3225H01L21/322
Inventor L·W·夏夫B·L·吉尔摩
Owner MEMC ELECTONIC MATERIALS INC
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