Evaporated AgBr as a potential photosensitive material for the new lithographies

Evaporated AgBr films of the order of 2000 Å thick exhibit sensitivity of the order of 50 µJ/cm²at wavelengths between 2600 and 3000 Å, of the same order of magnitude at the X-ray wavelength of 7 Å, and sensitivity of the order of 10^-9to 10^-10C/cm²to electron-beam excitation at potentials ranging from a few to 25 kV. This sensitivity derives in part from the large absorption (or stopping power) and in part from the amplification or gain in the development process (∼10⁵). The resolution is shown to be dependent upon grain size but most importantly upon the development process. The development process, now under active study, limits the present resolution to the order of 1 µm. In principle, the ultimate resolution, coupled with high gain, should approach that attainable with emulsions, namely about 5000 line pairs/mm. The proposed method of using evaporated AgBr in a photoresist system involves the deposition onto a relatively thick polymer, chosen for its resist properties. Image transfer from the photographically generated Ag image to the resist polymer is by dry etching techniques.