Browse Prior Art Database

Plasma Process Monitoring by Ellipsometry With Single Port Optical Access

IP.com Disclosure Number: IPCOM000120966D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Oehrlein, G: AUTHOR [+2]

Abstract

Disclosed is a geometrical arrangement of the optical parts of an ellipsometry system which needs only one port on a vacuum system for optical access. This is achieved by utilizing a mirror inside the vacuum system.

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Plasma Process Monitoring by Ellipsometry With Single Port Optical
Access

      Disclosed is a geometrical arrangement of the optical parts of
an ellipsometry system which needs only one port on a vacuum system
for optical access. This is achieved by utilizing a mirror inside the
vacuum system.

      Ellipsometry is a desirable technique for determining in-situ,
real-time the film thickness and the refractive index of a thin film
when grown or etched over a substrate. However, since a standard
ellipsometer requires two optical ports on a vacuum system, the
technique has not been widely used for real-time monitoring and
control of film growth or etching.

      The use of a mirror mounted inside the vacuum system eliminates
the need for one of the optical ports.  The mirror reflects the light
coming off the wafer surface back onto the wafer where it traverses
the film once more and leaves the chamber through the same optical
port as it entered the vacuum system.  The mirror is adjusted so that
the returning beam traverses a slightly different path from the
incoming beam in order to avoid interference.  This arrangement
eliminates the need for a second optical port which should be
important for manufacturing tools requiring ellipsometry as an
on-wafer real- time diagnostic technique.

      Disclosed anonymously.