Method and device for the production of a silicon single crystal, silicon single crystal, and silicon semiconductor wafers with determined defect distributions

Abstract

A method for the production of a silicon single crystal by pulling the single crystal, according to the Czochralski method, from a melt which is held in a rotating crucible, the single crystal growing at a growth front, heat being deliberately supplied to the center of the growth front by a heat flux directed at the growth front. The method produces a silicon single crystal with an oxygen content of from 4*10<17 >cm<-3 >to 7.2*10<17 >cm<-3 >and a radial concentration change for boron or phosphorus of less than 5%, which has no agglomerated self-point defects. Semiconductor wafers are separated from the single crystal. These semiconductor wafers have may have agglomerated vacancy defects (COPs) as the only self-point defect type or may have certain other defect distributions.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention[0001] The invention relates to a method for the production of a silicon single crystal by pulling the single crystal, according to the Czochralski method, from a melt which is held in a rotating crucible, with the single crystal growing at a growth front. The invention also relates to a silicon single crystal and to semiconductor wafers which are separated therefrom. 2. The Prior Art[0002] The production of single crystals which have a diameter of 200 mm or more represents a significant challenge, particularly since it is very difficult to deliberately adjust the radial crystal properties within a very narrow tolerance range. This applies to the concentration of impurities or dopants, and especially to the crystal defects and self-point defects, and agglomerates thereof. Self-point defects include interstitial silicon atoms (silicon self-interstitials) and vacancies, which are formed at the growth front of the single crystal. The...

AI Technical Summary

Benefits of technology

The invention relates to a method for producing silicon single crystals using the CZ-crystal growth method, which involves pulling the single crystal from a melt in a rotating crucible. The process is challenging because it requires precise control of radial crystal properties, such as impurities and defects, within a very narrow tolerance range. The invention aims to address this challenge by providing a method that can deliberately adjust the radial crystal properties, such as impurities and defects, to a high degree of accuracy. The invention also addresses the challenge of controlling the flow of heat in the melt, which affects the formation of crystal defects and impurities. The invention provides a method that can produce high-quality silicon single crystals with a low defect density.

Problems solved by technology

The production of single crystals which have a diameter of 200 mm or more represents a significant challenge, particularly since it is very difficult to deliberately adjust the radial crystal properties within a very narrow tolerance range.

The flows which transport heat in the melt are extremely difficult to predict.

They generally have a diameter of about 100 nm, and therefore cause problems for component fabrication.

These defects as well can also impair the functionality of the electronic components fabricated on silicon wafers.

This is not easy to achieve, however, especially when single crystals with a comparatively large diameter are being pulled, because the value of G then depends significantly on the radial position r. In general, owing to the radiative heat losses, the temperature gradient G is very much greater at the edge of the single crystal than at the center.

), can lead to there being several defect regions on a semiconductor wafer cut from a single crystal.

With the known prior art, however, sufficient radial V / G homogenization for the production of perfect silicon, especially with large crystal diameters, cannot be achieved in this way.

When analyzing the pulling tests which were carried out, it was found that insufficient radial homogenization of the ratio V / G.RTM.) is correlated with an inadequate heat supply from the melt to the center of the growth front.

They impede off-axial supply of heat to the melt.

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