Browse Prior Art Database

Vacuum-Compatible Low Contamination Wafer-Orientor System

IP.com Disclosure Number: IPCOM000060006D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Related People

Kulak, J: AUTHOR [+4]

Abstract

In semiconductor manufacturing, the alignment of wafers for processing is a critical step. A system is described for orienting the wafers with a minimum of contamination and no mechanical contact with the wafer edge or top surface. The wafer orientor can also be used within vacuum systems. The system is shown in Fig. 1, with the wafer 1 supported by a pedestal 2. In orienting the wafer, the objective is to align the center of the wafer with the axis of the pedestal. The pedestal 2 supports the wafer 1 and has both rotary (r) and vertical (z) motion. A high resolution micro-stepping motor 3 directly drives the pedestal 2 in the r direction, while the vertical movement is provided by a motor and eccentric cam arrangement (not shown).

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Vacuum-Compatible Low Contamination Wafer-Orientor System

In semiconductor manufacturing, the alignment of wafers for processing is a critical step. A system is described for orienting the wafers with a minimum of contamination and no mechanical contact with the wafer edge or top surface. The wafer orientor can also be used within vacuum systems. The system is shown in Fig. 1, with the wafer 1 supported by a pedestal 2. In orienting the wafer, the objective is to align the center of the wafer with the axis of the pedestal. The pedestal 2 supports the wafer 1 and has both rotary (r) and vertical (z) motion. A high resolution micro-stepping motor 3 directly drives the pedestal 2 in the r direction, while the vertical movement is provided by a motor and eccentric cam arrangement (not shown). If used in an atmospheric system, the face of the pedestal must be inscribed with shallow cross- channels to dissipate any air film which would develop during wafer transfer. Vacuum suction could be added to avoid wafer slippage during rotation. An x-corrector 4 is a single-axis linear drive mechanism whose primary function is to move the wafer 1 relative to the pedestal 2 in a controlled manner. The x-corrector 4 axis passes through the pedestal 2 center, with the pedestal travelling in the z-axis via an access opening in the center of the corrector. In operation, the wafer 1 on the pedestal 2 is deposited on the x-corrector 4 by lowering the pedestal to its "down" position. After the x-corrector 4 is moved the required distance, the wafer 1 is picked up by raising the pedestal 2 to its "up" position. A charge-coupled device linear array camera 5 is positioned so that the linear array is in line with the pedestal 2 center. The wafer 1 edge is backlighted by a uniform light source 6 directed toward a 45-degree prism 7 having one of its faces treated to create a diffusing screen. By backlighting the wafer 1 and looking at its edge from above, a distinct edge contour is imaged on the linear array. This image is converted to a digital representation of the edge position. A computer 8 is used to acquire and process the edge position information and control the various motion components of...