Argon Content of SiO₂ Films Deposited by RF Sputtering in Argon

Abstract

When Si0 2 is deposited by sputtering in an argon rf glow discharge, the films so produced contain considerable amounts of trapped argon, as determined by x-ray fluorescence analysis. This argon content was measured as a function of various sputtering parameters: argon pressure, rf power, electrode spacing, substrate temperature, and magnetic field, the latter two being most influential. A simple theoretical model for the capture and release of argon is presented which explains an observed linear decrease of the argon concentration in SiOz with increasing temperature. Incorporation of argon into the sputtered SiO. film does not seem to impair the film's ability to act as a good passivating and insulating layer.where 0"8 is the cross section for sputtering. Thus, while reflection of argon from filled sites, Eq. (1), and bombardment-induced re-emission, Eq. (2), are introduced as separate processes, their effects are indistinguishable.The impinging Si0 2 continuously buries sorbed argon, providing a fresh surface for further gas sorption.By using an argon-free glass surface, the rate of argon capture has been found to be proportional to the bombardment rate of argon ions." The capture process can be visualized: an incoming energetic argon ion or atom can strike the surface, either at an empty site where it will stick, or at an occupied site where it will be reflected. The net rate of argon capture can be written as:where / is the flux of energetic argon, 0" c is a proportionality constant or capture cross section, flo is the number of potential capture sites, and n is the number of filled sites.The release of sorbed gas by ion bombardment has been demonstrated clearly in experiments where one inert gas is used to recover another gas that had been previously sorbed." During the recovery process, the second gas is itself sorbed on the surface. Thus, the rate of sputtering re-emission can be given as (2) (1) luAno -n),

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The Influence of Noble Gas Atoms on the Epitaxial Growth of Implanted and Sputtered Amorphous Silicon

“…Ar as-sputtering gas.--Reported concentrations of Ar retention in sputtered films vary from about 0.5-15 a/o (4,5). The lowest Ar inclusion we could obtain in our Si films sputtered with Ar gas was 1.5 a/o.…”

High Quality RF‐Sputtered Silicon Dioxide Layers

“…The rf power had to be reduced toward the end of the etching to keep the damage of the Si so low that it could be removed by the same annealing procedure which is also customarily used on thermal SiO2. It is also sufficient to remove enclosed Ar (12) and defects in the sputtered SiO2 (13). Upon such annealing in N2 at 1050~ before and at 500~ after A1 deposition, MOS diodes of very good quality could be made, especially by reactively sputtering Si in an O2-Ar mixture.…”