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Browse Prior Art Database

Wafer Cassette Turntable for Multi-Wafer Integrated Processing

IP.com Disclosure Number: IPCOM000034398D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

DeFresart, E: AUTHOR [+2]

Abstract

A technique is described whereby a wafer cassette turntable simplifies the exchange transfer process of cassettes between high vacuum chambers during the integrated processing of semiconductor devices. In semiconductor fabrication, multichamber processing tools are important so as to reduce the exposure to impurities and particles. One example is the use of load lock systems: Wafers are introduced from the room into vacuum or controlled ambient chambers (the load lock), the load lock is evacuated, or equilibrated, and then the wafers are transferred from the load lock into the processing tool. This process provides the advantage of never directly exposing the wafers to impurities or particles of the room.

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Wafer Cassette Turntable for Multi-Wafer Integrated Processing

A technique is described whereby a wafer cassette turntable simplifies the exchange transfer process of cassettes between high vacuum chambers during the integrated processing of semiconductor devices. In semiconductor fabrication, multichamber processing tools are important so as to reduce the exposure to impurities and particles. One example is the use of load lock systems: Wafers are introduced from the room into vacuum or controlled ambient chambers (the load lock), the load lock is evacuated, or equilibrated, and then the wafers are transferred from the load lock into the processing tool. This process provides the advantage of never directly exposing the wafers to impurities or particles of the room. Another example involves the combination of several processing chambers with appropriate load lock and/or wafer transfer chambers. Environmental isolation and cleanliness is carried out sequentially (or integrated) by using connected transfer and load lock chambers. This process significantly reduces wafer surface/interface degradation (oxidation, contamination, etc.) as compared with processes which are exposed to room ambient environments. As a result, the use of multichambers and integrated processing provides better control and higher yield since contamination, recleaning and inspection are reduced. Multichamber processing tools typically will use multiple-wafer cassettes made of quartz and have the ability to hold a significant number of wafers at a time. The spectrum of the processing typically includes thermal oxidation, atmospheric and low pressure chemical vapor deposition (CVD) of oxides, nitrides, polysilicon, and ultrahigh vacuum deposition. However, problems can exist in the moving of wafer cassettes between the chambers. For example, in a low temperature epitaxy process, a wafer cassette is transferred between two ultra high vacuum CVD growth reactors. Each reactor consists of a long quartz tube and the cassette is placed near the center. To maintain reasonable lengths of linear transfer, the cassettes must be moved in orthogonal directions. The process of transferring the wafer cassettes from one reactor to another involves passing the cassettes through a transfer chamber, a load lock, through the second transfer chamber and finally into the second reactor. Manipulators are used to provide linear motion along the axis. The vacuum chambers must be isolated at appropriate times by closing a series of valves. If the orientation of the cassette remains the same during the complex series of transfers, the valves and the chambers must be l...