Formation of Nonnative Cu-BTA Surface Film

The etch rate of co( r with and without 1 wt% BTA added to the etch solution vs. HNO3 concentration. 

In principle, the addition of BTA to the slurry should provide an effective surface layer during polishing. However, the Cu-BTA layer must (1) not inhibit the polishing action in the high areas and (2) remain intact on the low areas, i.e., must be mechani- 

The polish rate of copper on 125 mm wafers using a Strasbaugh 6CU polisher and a slurry of alumina abrasive, 1 vol% HNO3, and 0.1 wt% BTA slurry is 0.84 pm/min, 70% of the polish rate of 1.0 pm/min obtained without the BTA. Therefore, the BTA does inhibit the polishing to some extent. However, the polish rate is still considerably higher than the rate in NHjOH or HjO slurries. 

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