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Monitoring Thickness During Radio Frequency Sputtering

IP.com Disclosure Number: IPCOM000074805D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Sarkary, HG: AUTHOR

Abstract

It is possible to monitor the thickness in an radio-frequency (R.F.) sputtering operation by using a substrate (wafer) material which is more than about 75% transparent to infrared (IR) light at the wavelength range of an IR detector. The detector 10 is focused with the aid of mirror 11 on a transparent wafer 12 through a hole drilled in the bottom anode plate 14, as shown in Fig. 1. The cathode or target 16 of the apparatus is also shown.

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Monitoring Thickness During Radio Frequency Sputtering

It is possible to monitor the thickness in an radio-frequency (R.F.) sputtering operation by using a substrate (wafer) material which is more than about 75% transparent to infrared (IR) light at the wavelength range of an IR detector. The detector 10 is focused with the aid of mirror 11 on a transparent wafer 12 through a hole drilled in the bottom anode plate 14, as shown in Fig. 1. The cathode or target 16 of the apparatus is also shown.

Spectral emissivity of the wafer changes sinusoidally with increasing thickness of the material being deposited. This has been verified experimentally wherein silicon dioxide was deposited. A series of maxima and minima are observed in Fig. 2 for temperature as a function of time when keeping the spectral emissivity constant at a low value of about 0.2 or less. The added advantages of backside measurements are (1) that the plasma (R.F.) does not interfere with the IR detector, and (2) with increasing size of the chambers and decreased cathode-anode (electrode) spacing, this technique shows obvious advantages. The thickness at any point during sputtering is thus obtained by making use of the number of maxima and minima at that time.

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