Browse Prior Art Database

Directional Snow Clean Process

IP.com Disclosure Number: IPCOM000014109D
Original Publication Date: 2001-Aug-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 109K

Publishing Venue

IBM

Abstract

Snow cleaning is a process where an intense CO2 stream is directed towards the wafer. The gas/particle stream is capable of removing poorly adhesive material. A commercially available tool exists [1]. This tool allows choosing between two different nozzles with different pressures (non aggressive snow clean and aggressive snow clean). The wafer is rotated during process so that the stream hits the wafer from different directions. In this publication, an advancement of the snow clean process is disclosed, called directional snow clean. Directional snow clean means that the wafer is oriented in a well defined angle to the direction of the CO2 stream. This requires an automatic wafer aligning system in combination with an adjustable or controllable angle of incidence for the snow stream. In contrast to standard snow clean process, directional snow clean process allows removing selective particles. Furthermore, damages can be circumvented which are caused by a stream hitting the broadside of fine structures.

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Directional Snow Clean Process

  Snow cleaning is a process where an intense CO2 stream is directed towards the wafer. The gas/particle stream is capable of removing poorly adhesive material. A commercially available tool exists [1]. This tool allows choosing between two different nozzles with different pressures (non aggressive snow clean and aggressive snow clean). The wafer is rotated during process so that the stream hits the wafer from different directions. In this publication, an advancement of the snow clean process is disclosed, called directional snow clean. Directional snow clean means that the wafer is oriented in a well defined angle to the direction of the CO2 stream. This requires an automatic wafer aligning system in combination with an adjustable or controllable angle of incidence for the snow stream. In contrast to standard snow clean process, directional snow clean process allows removing selective particles. Furthermore, damages can be circumvented which are caused by a stream hitting the broadside of fine structures.

  Multi-step ion mill processes including different angles of ion incidence are state of the art in production of magnetic read write heads. One typical example is the shaping of the pole tip of the write head. Extremely critical dimensions are realized by means of trimming and notching of the pole zone. However, as a side effect, redeposited material can occur (see Fig.1). These structures are useless. They not only create cavities,...