Convenient Technique to Determine Dose On Deep Uv Lithographic Exposure Equipment

Convenient Technique to Determine Dose On Deep Uv Lithographic Exposure Equipment

       This invention describes a new method for actinometry at
deep UV wavelengths using a polymeric dosimetry film.  It has been
found that one can prepare these films by placing a Deep UV
photosensitive compound into a transparent matrix resin.  As a
specific example, 5-diazomeldrum's acid(*) (I) in
polymethylmethacrylate (PMMA) has the desired optical and mechanical
properties required for a 248 nm dosimetry film.

      Example In order to demonstrate that this invention works, a
dosimetry film was prepared consisting of I in PMMA and this material
was used to calibrate a Deep UV projection aligner (Perkin-Elmer
500).  This PE-500 uses "scan speed" as an arbitrary energy unit, and
this demonstration will use the Meldrum's diazo dosimetry film to
relate "scan speed" to mJ/cm2 .

      The dosimetry film was prepared by dissolving 0.1 g I in 8.0 g
of a 10% PMMA solution (Wt % in arcosolve).  The solution was spin
coated at 3000 rpm for 60 seconds onto a quartz substrate to afford a
0.5m thick film (absorbance of 0.3 at 248 nm).  The coated dosimetry
film should not be heated after spin coating.

      A calibration curve was prepared to determine the relationship
between 248 nm exposure dose and Meldrum's diazo film absorbance.
This was accomplished using a 248 nm band pass filter and an OAI DUV
flood exposure station.  The flux through the 248 nm band pass filter
was...