Recently there has been a tremendous increase in positive photoresist technology to manufacture fine line semiconductor devices. However capabilities of current positive resist can not satisfy LSI production requirements, especially on linewidth control. In this paper new positive photoresists, AZ-1450J, HPR-204 and OFPR-800 were studied to minimize linewidth precision of MOS dynamic RAMs using 1:1 scanning projection systems. In order to optimize resist linewidth characteristics of new materials, i.e. exposure sensitivity, striation, chemical stability, wet developing, resistance for new dry etching, removal and impurity, were evaluated for each material. And the availability was confirmed by application to the test device for MOS dynamic RAM. This is including 128 X 10 transistor arrays with various channel length and possible to measure the threshold voltage imbalance of transistors by scanning of a decoder circuit. Consequently it was found that the channel length variation decreased within 0.1 1111 ( 3o-'). and the threshold voltage variation was ∓ 50 mV ( 3σ ) or less for 2 μm line using AZ-1450J and OFPR-800.