Browse Prior Art Database

PLASMA ETCHING OF THICK OXIDES WITHOUT PHOTORESIST RETICULATION

IP.com Disclosure Number: IPCOM000005918D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2001-Nov-15
Document File: 1 page(s) / 41K

Publishing Venue

Motorola

Related People

Andrew Nagy: AUTHOR

Abstract

During very long (i.e. > 20 minute) plasma etched, such as those typically used to etch via through glass in metal interconnect structures, the wafers will reach temperatures high enough to cause reticulation or flow of the patterning photoresist. The wavers reach these temperatures (>130%) because of poor thermal conductivity between the wafer and the cooled pedestal against which'it rests during the etch. This problem is most prevalent in batch hexode systems where efficient backside cooling of wafers is mechanically very difficult. One way around this problem without com- promising the other characteristics of the etch (i.e. the etch rate and uniformity) is to add one or more "cool down" steps to the process. During these steps, the system is run at as high an operating pressure as the pumping package will allow (typically about 200 mTorr) with gas flowing, but without rf. The cool down step (or steps) is typically five minutes long. This high pressure, high flow step allows improved thermal conductivity between the wafer and the pedestal, which allows the wafer to cool. With the etch broken up by the appropriate number of cool down steps, the wafer is not allowed to reach a temperature high enough to cause resist flow.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

0 M

MOlVROLA Technical Developments Volume 10 March 1990

f .,

PLASMA ETCHING OF THICK OXIDES

WITHOUT PHOTORESIST RETICULATION

by Andrew Nagy

   During very long (i.e. > 20 minute) plasma etched, such as those typically used to etch via through glass in metal interconnect structures, the wafers will reach temperatures high enough to cause reticulation or flow of the patterning photoresist. The wavers reach these temperatures (>130%) because of poor thermal conductivity between the wafer and the cooled pedestal against which'it rests during the etch. This problem is most prevalent in batch hexode systems where efficient backside cooling of wafers is mechanically very difficult. One way around this problem without com- promising the other characteristics of the etch (i.e. the etch rate and uniformity) is to add one or more "cool down" steps to the process. During these steps, the system is run at as high an operating pressure as the pumping package will allow (typically about 200 mTorr) with gas flowing, but without rf. The cool down step (or steps) is typically five minutes long. This high pressure, high flow step allows improved thermal conductivity between the wafer and the pedestal, which allows the wafer to cool. With the etch broken up by the appropriate number of cool down steps, the wafer is not allowed to reach a temperature high enough to cause resist flow.

0 Motorola, Inc. 1990 91

[This page contains 14 pictures or other non-text objects]