Photoresist Exposure Using Multiple Wavelengths
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15
Advantages of greater tolerance of depth of focus, better planarization, isolation of wafer topography from image control, and added degrees of freedom in profile control found with multilayer photoresist processes can be attained with single layer photoresists when using multiple exposure wavelengths. After application of a single layer 1 of photoresist to wafer 2, as shown in Fig. 1, exposure is done with consideration given the differential spectral characteristics of absorption and sensitivity of the photoresist. Exposure having critical dimensions is done at a wavelength that is highly absorbed so that the top part 3 of the layer is exposed. A different wavelength of less absorption is used to expose the underlying resist layer to create support 4 for the image 3 on top, since dimensions of bulk exposure are less critical.