The effect of developer temperature on the development rates and line edge profiles of electron beam and optically exposed diazo-type photoresists were investigated. An in situ thickness measurement tool (FTA) was used to monitor the development rates; and activation energies based on a simple Arrhenius dependence were calculated. For the positive diazo-resist system AZ-1350J exposed to e-beam. the activation energies and line edge profiles are temperature dependent. Both optically and e-beam exposed resists give greater contrast, straighter line edge profiles, and linewidth control at low temperatures (10°-15°C). For AZ-2400 exposed optically and with e-beam, the activation energies and line edge profiles are independent of temperature, indicating that developer temperature is a less critical parameter for AZ-2400 than for AZ-1350J. © 1979, The Electrochemical Society, Inc. All rights reserved.