Positive diazo-type photoresists are a very attractive alternative to conventional electron resists such as PMMA. They can be used as both positive and negative electron resists with a resolution well into the submicron range. We first give an overview of the negative resist process and describe the effect of electron dose, optical dose and development time on the resist profiles. We then present a method of evaluation used to optimize the profiles. Several resist systems with a variety of developers were investigated with the goal of producing resist profiles with sidewalls approaching 900. One of our primary concerns was to maintain a forgiving process that was relatively intolerant to changes in processing parameters such as development time. The numerous processing parameters that come into play in the negative resist process are described and the specifics given for a few of the "best" resist/developer systems that we identified. We found that negative-mode diazo-type electron resists are particularly prone to intraproximity effects, but that these effects are dependent upon the particular resist system and developer concentration and could be minimized. The method of evaluation described here should enable the reader to systematically determine a viable negative electron resist system for his particular application.