Imaging studies have confirmed that a desired resist profile can be obtained by selecting the appropriate combination of process parameters: dose, interrupted development, pattern bias, and resist thickness. Bias sensitivity of the resist image to process parameters was measured using a positive diazo resist with nonlinear development characteristics on an IBM EL-3 E-beam tool. Because of superior bias stability, top-edge imaging with undercut profiles in a single-layer resist was found to provide many of the imaging advantages of a multilayer system. Sufficient resolution and image quality are obtained to extend the application of a single-layer resist system to 1-µm lithography.
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