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Acid/Base Removal of Al-Cu Discharge Layer From E-Beam Resist

IP.com Disclosure Number: IPCOM000102451D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Klymko, PW: AUTHOR

Abstract

Disclosed is a general method for the removal of an Al-Cu discharge layer from an undeveloped sulfone-novolak resist using acid or basic strip solutions. The requirements for any strip solution based on the stability of the active resist, the stability of the discharge layer, and the kinetics of discharge layer removal are presented.

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This is the abbreviated version, containing approximately 65% of the total text.

Acid/Base Removal of Al-Cu Discharge Layer From E-Beam Resist

       Disclosed is a general method for the removal of an Al-Cu
discharge layer from an undeveloped sulfone-novolak resist using acid
or basic strip solutions.  The requirements for any strip solution
based on the stability of the active resist, the stability of the
discharge layer, and the kinetics of discharge layer removal are
presented.

      When a sulfone-novolak resist is used with an Al-Cu discharge
layer, the unexposed portion of the resist is damaged.  Although the
discharge layer can be removed in the same step as resist developing,
the resist damage results in poor contrast and increased defect
levels.  Use of a separate discharge layer strip followed by a baking
prior to developing was previously shown to partially repair the
resist damage.  However, the technique was limited to the use of
buffered HF as a stripping agent as other stripping agents tested
were found to further damage the resist. Further, HF was found to
occasionally leave insoluble hydrated precipitates of AlF3 on the
resist surface resulting in defects.

      The disclosed method uses a general acid or base strip that
does not damage the resist, and can be formulated to avoid
precipitate formation.  It was determined that the active resist
could withstand short term exposure to acid solutions with a pH as
low as 1.  The thermodynamic requirement for acid removal of the
aluminum is pH < 4.  An effective range fo...