Browse Prior Art Database

New Type of Pod to Secure Wafers during Transit

IP.com Disclosure Number: IPCOM000099084D
Published in the IP.com Journal: Volume 5 Issue 4 (2005-04-16)
Included in the Prior Art Database: 2005-Apr-16
Document File: 3 page(s) / 638K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In the computer-chip technology wafers are carried with SMIF pods (Standard Mechanical Interface pods) or FOUPs (Front Opening Unified Pods). SMIF-pods and FOUP's have been used with success for a number of years however defects which find their way into the pod can cause still problems. This can be made worse by the movement of the wafers during transit of the pod. If wafers could be held securely in the carrier then it should be possible to minimize the movement of defects and minimize cross contamination which is always possible. Defects often get stuck to the back of the wafer and can be transported into the pod this way. Securing the wafer would also stop the top edge of the wafer being touched by the cassette. This region can often be a source of defects due to excessive etching at the wafer edge. A new method to secure wafers within the pod is to use vacuum. Small grooves can be machined into the rails on which the wafer rests on. These grooves allow a vacuum to be applied. This will hold the wafer during normal horizontal transit. The internal construction is similar to the vacuum pencil used to lift wafers out of a cassette. Preferred the pod has to be vacuum tight, at least to a low vacuum level (<10Torr). Maintaining vacuum over relatively short periods of time is not difficult. The wafers are effectively in parallel to each other so this means that it has to be assured that a full cassette or tiny valves exist to allow empty slots to exit. These valves would have to shut if an empty slot exists.

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New Type of Pod to Secure Wafers during Transit

Idea: Dr. Kevin Pears, DE-Dresden

In the computer-chip technology wafers are carried with SMIF pods (Standard Mechanical Interface pods) or FOUPs (Front Opening Unified Pods). SMIF-pods and FOUP's have been used with success for a number of years however defects which find their way into the pod can cause still problems. This can be made worse by the movement of the wafers during transit of the pod.

If wafers could be held securely in the carrier then it should be possible to minimize the movement of defects and minimize cross contamination which is always possible. Defects often get stuck to the back of the wafer and can be transported into the pod this way. Securing the wafer would also stop the top edge of the wafer being touched by the cassette. This region can often be a source of defects due to excessive etching at the wafer edge.

A new method to secure wafers within the pod is to use vacuum. Small grooves can be machined into the rails on which the wafer rests on. These grooves allow a vacuum to be applied. This will hold the wafer during normal horizontal transit. The internal construction is similar to the vacuum pencil used to lift wafers out of a cassette.

Preferred the pod has to be vacuum tight, at least to a low vacuum level (<10Torr). Maintaining vacuum over relatively short periods of time is not difficult.

The wafers are effectively in parallel to each other so this means that it has to be assured...