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Automated, Remote, Programmable, Ellipsometer Drive Mechanism

IP.com Disclosure Number: IPCOM000034339D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 5 page(s) / 209K

Publishing Venue

IBM

Related People

Donald, GW: AUTHOR [+3]

Abstract

A technique is described whereby a drive mechanism is adapted to multiple angle Ellipsometers, as used in measuring film thickness, so as to permit automated, remote, programmability. The mechanism is particularly adaptable to "clean room" applications and where operator protection must be considered for protection from exposure to stray Laser beam reflection. (Image Omitted) The Ellipsometer drive mechanism is designed to function with a base station, which provides the equipment to mount the Ellipsometer, vibration isolation, X-Y-Z-theta stage, wafer orientor and transport, and the basic control system. The Ellipsometer consists of a Laser/ Polarizer, Analyzer, Collimator, Nose Piece Slide Assembly and a Video system.

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Automated, Remote, Programmable, Ellipsometer Drive Mechanism

A technique is described whereby a drive mechanism is adapted to multiple angle Ellipsometers, as used in measuring film thickness, so as to permit automated, remote, programmability. The mechanism is particularly adaptable to "clean room" applications and where operator protection must be considered for protection from exposure to stray Laser beam reflection.

(Image Omitted)

The Ellipsometer drive mechanism is designed to function with a base station, which provides the equipment to mount the Ellipsometer, vibration isolation, X-Y-Z-theta stage, wafer orientor and transport, and the basic control system. The Ellipsometer consists of a Laser/ Polarizer, Analyzer, Collimator, Nose Piece Slide Assembly and a Video system. The mechanism is located over the existing base station such that the major support is a machined post at the rear of the base assembly so as to provide the pivot for left and right Ellipsometer segments 1 and drive segments 2, as shown in Figs. 1 and
2. The main shaft center is located on the center line through the theoretical focal points of Ellipsometer Laser 3 and Analyzer 4, as shown in Fig. 2. It is perpendicular to the plane described by the center lines of rotating Laser 3 and Analyzer 4.

(Image Omitted)

Bearings mounted in each of the segments and subsequently located on the main shaft provide the location and support for Laser 3, Analyzer 4 and drive segments 2. Front plate and rear support posts are bridged across the top with solid beam 5, which also locates and supports the Microscope components, Collimator system, Auto-focus, Video Camera and Nose Piece Slide assembly. Laser 3 and Analyzer 4 are also bridged, from front to rear, and a pair of bearings 6 mounted behind the front support plate can provide a location and pivot point at the front of the system. Front support plate 7 and rear post 8 are both mounted on the base supporting the X-Y Stage assembly

(Image Omitted)

Polarized drive 10, as shown in Fig. 3 and 4, is mounted on Laser support bridge 9 to rotate a polarizer drum. An existing knurl plate on the drum has been replaced with a gear, which is driven by a smaller gear mounted through a coupling to a stepping motor which operates at 36,000 steps/revolution so as to provide a .0025 degree/step output at the Polarizer. A pair of photo-sensing switches are utilized to sense the "zero" position of the Polarizer. One switch at the stepping motor and the other at the polarizer drum are connected in series and adjusted...