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Sharp Resist Profiles by Thermally Enhanced Development

IP.com Disclosure Number: IPCOM000119333D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 147K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+2]

Abstract

Prior art (1,2) have shown that the use of chilled developer can lead to much sharper and even undercut resist profiles. Such profiles are necessary for lift-off processing. The use of chilled developer is cumbersome because chilling equipment is not generally available in clean rooms: hence, ice water is generally used as the coolant. This effectively limits the temperature of the process to 0 degrees Celsius, whereas some other temperature could produce more optimum results.

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Sharp Resist Profiles by Thermally Enhanced Development

      Prior art (1,2) have shown that the use of chilled
developer can lead to much sharper and even undercut resist profiles.
Such profiles are necessary for lift-off processing.  The use of
chilled developer is cumbersome because chilling equipment is not
generally available in clean rooms: hence, ice water is generally
used as the coolant.  This effectively limits the temperature of the
process to 0 degrees Celsius, whereas some other temperature could
produce more optimum results.

      Disclosed is a process that provides a resist profile that is
generated by thermal enhancement, i.e., elevated temperature
development.  Fig. 1 is a SEM of typical resist profile when both
wafer and developer are at room temperature.  Fig. 2 is a SEM which
shows the known result for the case when the developer is chilled to
zero de grees Celsius, while the wafer is kept at room temperature
until it is dipped in the developer.  The steep angle of the resist
is apparent for the chilled developer case.  Fig. 3 is a series of
SEMs that shows the sequence of resist profiles for the case when the
wafer is heated to 40 degrees Celsius before dipping into developer
at 18 degrees Celsius. This sequence clearly shows the profile
steepening as development becomes more complete.  The final result is
equivalent to or better than that obtained with the chilled
developer.  This proves that the process responsible for this effect
depends more on the initial temperature difference between...