| This work is about the synthesis of photo reactive hyperbranched polyesters modified with epoxy resin, the preparation of negative thick photoresists with these photo reactive polyesters, and application as the mask in the chemical etching for microfabrication of glass. Photo reactive hyperbranched polyesters terminated with-COOH were prepared by trmellitic anhydride, epichlorohydrin and grycidol methacrylate. The modification of the polyesters was performed through the reaction of the epoxy groups on the epoxy resin with the -COOH. A serios of photosensitive resins with difference in photosensitivity were prepared and was characterized by GPC, DSC and TGA. Photocuring behaviours of resin and the photoresists were studied. Sensitivity and contract of the photoresists were measured by gel content High sensitivity and high contract (T0, gel andγgel were 2.71s and 2.802, respectively) were realized. Clear patterns with smooth surface and resolution reached to 2～3μm were prepared with the photoresists through contact exposure with mixed UV light.Effects of reactive diluents and additives on the properties of the photosists were studied. The photolithographic conditions and the developing solution for the thick negative-tone UV photoresist were defined as: prebaking at 65℃for 20～25min, exposure time 5min; developed for 5 min in acetone/ethanol=3 (m/m) and post baking at 70℃. With single-layer coatings the thicknesses of the dried photoresist over 50μm was achieved, and over 100μm thicknesses was also achieved by mulicoating. The aspect ratio of thick (80μm) photoresist was about 1:1.Photo masks for glass etching were prepared with the photoresists composed of the modified photoreactive resins. The wet chemical etching agents made of HF and HCl, HNO3 exhibited high etching rate (≥35μm/min). Photoresists made of the modified photoreactive hyperbranched polyesters were patterned with line width of 50μm. Glass etching with depth for over 38μm was realized using the photoresist as the only mask.
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