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Surface Modification by High Pressure Sputtering

IP.com Disclosure Number: IPCOM000061421D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+2]

Abstract

An object is treated by using it as a sputtering target and then sputtering it in an inert gas, such as argon, in a high pressure plasma (pressure is greater than 100mTorr). Thus, sputtering rearranges the position of the atoms on the object so the atoms redeposit on the object, but they are in different locations than they had been. That tends to increase the homogeneity of composition of the surface of the material. In addition, certain species in an alloy which are sputtered more easily may be depleted from the surface. For example in stainless steel, the Cr composition of the surface is increased as the other elements in the alloy are sputtered away to a somewhat greater degree.

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Surface Modification by High Pressure Sputtering

An object is treated by using it as a sputtering target and then sputtering it in an inert gas, such as argon, in a high pressure plasma (pressure is greater than 100mTorr). Thus, sputtering rearranges the position of the atoms on the object so the atoms redeposit on the object, but they are in different locations than they had been. That tends to increase the homogeneity of composition of the surface of the material. In addition, certain species in an alloy which are sputtered more easily may be depleted from the surface. For example in stainless steel, the Cr composition of the surface is increased as the other elements in the alloy are sputtered away to a somewhat greater degree.

This treatment modifies the surface of the object and can result in improved properties such as corrosion resistance, hardness, friction and wear.

When a target is sputtered in a high pressure plasma (P > _ 100 mTorr) the sputtered atoms thermalize a short distance from the target. Then the sputtered atoms may diffuse back to the target so the net transport from the target is small. The target surface, however, is significantly modified by this treatment. In particular, we found that high pressure sputtering imparts enhanced corrosion resistance and other useful properties to the surface.

For example, samples of 304 stainless steel sheet were sandblasted, electropolished, masked and exposed to argon sputtering pressures of 100, 310 and 250mTorr. The corrosion res are shown in Table I.

Decreased corrosion rates of 17% to 26.5% were seen. The bigges...