AbstractHyperbranched polymers containing carboxyl and acryloxyl groups were prepared through a one‐step synthesis with metatrimellitic anhydride, epichlorohydrin, and methylacrylic acid glycidic ester. The photo‐sensitivity coefficients of the polymer resists varied with the resin acid values and formulas. The linear depth was the reverse of the contrast. When the contrast was less than 0.49, the linear depth could reach 43 μm. The hyperbranched polyester resists were used to prepare microlens arrays. Moreover, there was a slight discrepancy between the element profile and simulated profile of the formed resists. The etching depth could reach 50 μm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1259–1263, 2004