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Transparent Film Growth Rate and Thickness Monitor

IP.com Disclosure Number: IPCOM000092894D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Boss, DW: AUTHOR [+3]

Abstract

The thickness and film growth rate can be determined during the deposition of transparent dielectric films such as silicon dioxide, aluminum oxide, silicon nitride and combinations thereof. An infrared light detector which has a sensitive wavelength peak at about two microns is utilized to detech the radiant energy emitted from the surface of the film being deposited.

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Transparent Film Growth Rate and Thickness Monitor

The thickness and film growth rate can be determined during the deposition of transparent dielectric films such as silicon dioxide, aluminum oxide, silicon nitride and combinations thereof. An infrared light detector which has a sensitive wavelength peak at about two microns is utilized to detech the radiant energy emitted from the surface of the film being deposited.

The transparent films are grown by pyrolytic deposition over a range of about 300 degrees C to 800 degrees C. The infrared light detector produces a continuous output signal during this growth period such as shown. The variation in the light detector output amplitude is due to transmission interference effects within the film being grown. In particular, the frequency of the light detector output variation is due to the wavelength specification of the light detector device, the refractive index and dispersion of the growing film, the angle of observation of the light detector, and the growth rate of the film.

The first three parameters can be determined and remain constant throughout the growth of the transparent film. The effective wavelength lambda is determined by the first three parameters. The interference maxima yield a film thickness X(L)=(2K+1)lambda/4 and the interference minima yield X(L1)l=K lambda/2 where the order K = 0, 1, 2. . . . The layer growth rate G is determined by G = X(L)/t where t is the run time. Thus continuous monitoring te...