Technique for Multilayer Photoresist Coating
Original Publication Date: 1978-Jun-01
Included in the Prior Art Database: 2005-Feb-21
Multilayer coating of photoresists requires a substantial high temperature bake of the previous layers in order to avoid dissolving away most or some of the preceding layer because of their mutual solubility in the coating solvent. For example, a layer of 13,000 Angstroms A2 1350J* resist baked at 85 Degrees C for 20 minutes was spun-coated with another layer of the same resist to form a two-coat thickness of much less than the expected 26,000 Angstroms (normally about 18,000 Angstroms was obtained). A much higher prebake temperature, for example, 120 Degrees C, is necessary to achieve a 26,000 Angstroms total thickness. However, baking at such high temperatures makes the photoresist less sensitive to light or other exposure radiation.