May 12, 2005  19  US 2005/0100814 Al  [0207]  A  formulation containing a terpolymer similar to  that described in this example and base I. described above  was exposed, developed and tested in a similar fashion to  that described in Example 9 and showed an improvement in  resolution.  [0208]  Example 7 was repeated with the following excep› tions: The following solution was prepared and magnetically  stirred:  [0209]  To ten 5.0 gm samples of the above solution were  added 0.128 gm of a 0.0232  M  solution of one of each of the  bases disclosed in Example 7 dissolved in 2-heptanone, and  stirred overnight.  [0210]  Wafers were coated and prepared as described in  Example 7 except that exposure time was 3 seconds instead  of 10 seconds, providing an unattenuated dose of 4.0  mJ/cm 2 .  [0211]  This test generated positive images, with the fol› lowing clearing doses (mJ/cm 2 )  required for the formula› tions with the above bases:  [0213]  This resist formulation was spin cast on an 8 inch  Si wafer at a speed of 2000 rpm, yielding a film of measured  thickness 2169  A  after PAE at 120°  C. for 60 sec.  [0214]  All imaging and open frame exposures were made  using an Exitech 157 nm microstepper. Resist formulations  were spin-coated on 8 inch Si wafers which were first vapor  primed at 90°  C. with hexamethyldisilazane (HMDS). The  resulting films were soft baked, or post-apply baked (PAE),  at 120° C. for 60 sec, and then their thicknesses were  measured using a Prometrix interferometer which utilized  Cauchy coefficients determined by variable angle spectro› scopic ellipsometry measurements using a  J.A.  Woollam  VU301 variable angle spectroscopic ellipsometer. After  open frame exposure on the Exitech stepper (typically 100  exposure doses were made), or imaging using either a binary  mask with numerical aperture (N.A.)=0.6 and partial coher› ence (a)=0.7, or a Levenson strong phase shift mask with  N.A.=0.6 and  a=0.3,  the wafer was post-exposure baked  (PEE) at 100°  C. for 60 sec followed by a 60 sec puddle  develop with Shipley LDD-26W 2.38% tetramethyl ammo› nium hydroxide. The open frame exposed wafers were then  subjected to thickness measurements on the Prometrix inter› ferometer in order to determine the thickness loss versus  exposure dose, and the imaged wafers were examined using  a JEOL 7550 top-down and tilt scanning electron micro› scope (SEM), and in some cases cross-sections were made  and examined using a Hitachi 4500 SEM.  [0215]  At an exposure dose of 24 mJ/cm 2  the image was  found to exhibit features at 140 nm resolution.  [0216]  The same polymer formulation was used, but with  the addition of 38 microliters of 0.5 wt % tetrabutylammo› nium lactate (TBALac) base to 1 milliliter of the resist. This  corresponds to a molar concentration of the base equal to  10% of the molar concentration of the PAG. This formula› tion was spin cast on an 8 inch Si wafer at 2000 rpm,  yielding after PAE at 120°  C. for 60 sec a film of thickness  2087  A.  This film was exposed and developed as described  above. The resulting image was then examined in the JEOL  7550 SEM and was observed to exhibit features at least as  small as 60 nm at an exposure dose of 52 mJ/cm 2 .  These  features were also examined in cross-section using the  Hitachi 4500 SEM, and 100 nm 1:2 lines and spaces were  well resolved and exhibited good line profiles, as did 60 nm  1:5 lines and spaces. These results demonstrate that this  vinyl addition polymer can image at sub-100 nm resolution,  with film thcknesses exceeding 200 nm, when formulated  with added base.  [0212]  The following solution was prepared, magnetically  stirred overnight, and filtered through a  0.45µ  PTFE syringe  filter before use:  Example 9B  Example A  A. 2.4 mJ/cm 2  B. 1.2 mJ/cm 2  C. 1.0 mJ /cm 2  D. 1.2 mJ/cm 2  E. 2.1 mJ/cm 2  F.  2.1 mJ/cm 2  G. 1.2 mJ/cm 2  H. 1.2 mJ/cm 2  I.  2.4 mJ/cm 2  J. 2.4 mJ/cm 2  A. 3.9 mJ/cm 2  B. 3.2 mJ/cm 2  C. 2.4 mJ /cm 2  D.  3.2 mJ/cm 2  E. 6.8 mJ/cm 2  F.  3.9 mJ/cm 2  G. 3.9 mJ/cm 2  H. 2.4 mJ/cm 2  I.  5.3 mJ/cm 2  J. 2.4 mJ/cm 2  Example 8  Component  NB-Me-F--OH/NB-Me-F--0-tBuAc  (68/32) copolymer prepared  similarly to that in Example 5  2-Heptanone  6.82% (wt) solution of triphenylsulfonium  nonaflate dissolved in cyclohexanone  which had been filtered through a  0.45µ  PTFE syringe filter.  Wt. (gm)  1.739  12.364  0.897  Component  NB-Me-F--OH/NB-Me-F--0-Ac-tBu copolymer  (68/32, as analyzed by $^{19}$F NMR) similar to that  described in Example 5  2-Heptanone  6.82% (wt) solution of triphenylsulfonium nonaflate  dissolved in 2-heptanone which had been  filtered through a  0.45µ  PTFE syringe filter.  Wt. (gm)  6.607  46.983  3.410 