Copper sputtering targets and methods of forming copper sputtering targets

Abstract

The invention includes a copper-comprising sputtering target. The target is monolithic or bonded and contains at least 99.99% copper by weight and has an average grain size of from 1 micron to 50 microns. The copper-comprising target has a yield strength of greater than or equal to about 15 ksi and a Brinell hardness (HB) of greater than about 40. The invention includes copper alloy monolithic and bonded sputtering targets consisting essentially of less than or equal to about 99.99% copper by weight and a total amount of alloying element(s) of at least 100 ppm and less than 10% by weight. The targets have an average grain size of from less than 1 micron to 50 microns and have a grain size non-uniformity of less than about 15% standard deviation (1-sigma) throughout the target. The invention additionally includes methods of producing bonded and monolithic copper and copper alloy targets.

Description

RELATED PATENT DATA[0001] This patent is a continuation in part of U.S. patent application Ser. No. 09 / 465,492 which was filed on Dec. 16, 1999 and which is herein incorporated by reference. This patent further claims benefit of priority under 35 U.S.C. .sctn.119 to U.S. Provisional Patent Serial No. 60 / 396,544, which was filed Jul. 16, 2002, and to U.S. Provisional Patent Serial No.: Not Yet Assigned, entitled Copper Sputtering Targets and Methods of Forming Copper Sputtering Targets, which was filed May 15, 2003.[0002] The invention pertains to copper-comprising monolithic sputtering targets and copper-comprising bonded sputtering targets. The invention additionally pertains to methods of forming copper-comprising monolithic and bonded sputtering targets.[0003] High-purity copper sputtering targets and copper alloy sputtering targets are currently used in a variety of applications including, for example, fabrication of integrated circuits. The quality of copper-comprising structur...

AI Technical Summary

Problems solved by technology

However, the high temperatures utilized during bonding of the copper target to the backing plate often results in abnormal grain growth resulting in non-uniformity of microstructure and an increase in overall average grain size.

Conventional high-purity copper targets typically have an average grain size greater than 50 microns which can result in relatively low yield strength.

The resulting grain size and structural non-uniformity of conventionally formed high-purity copper sputtering targets can detrimentally affect the quality of sputter-deposited high-purity copper films and interconnects.

In addition to the resulting large grain size and anomalous grain growth that can result during bonding processes, diffusion bonded copper targets are often plagued by problems such as burn through and short target life.

Additionally, bonding processes can be complicated and time consuming.

Another draw back to alloying can be potential defects such as formation of second phase precipitates or segregation.

Although treatment of conventional materials for reduction or removal of precipitates or segregation defects may be possible in some instances, such treatment typically includes high temperatures which can result in extremely large grain sizes (greater than 150 microns).

However, the remaining defects can still affect the quality of sputtered films.

Such low temperature or absence of anneal can result in a blank having an average grain size of less than about 1 micron.

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