| 摘要 |
PURPOSE:To improve the gamma value (or contrast) thereby to form a resist pattern, which is clear even for a fine mask pattern, by using a mixture resist which is composed of two types of negative photoresists having different optical sensitivities. CONSTITUTION:A negative photoresist having a higher optical sensitivity and a negative photoresist having a lower optical sensitivity are mixed to prepare a mixture photoresist having a high gamma value. In this mixture photoresist, the resist having a higher sensitivity (as shown in an optical sensitivity curve 10) has its optical polymerization prohibited under the influence of the resist having a lower sensitivity (as shown in an optical sensitivity curve 11) in case the optical radiation is at a low level. When the optical radiation becomes high, on the contrary, the above influence becomes negligible so that a similar optical polymerization to the case, in which only the resist having a higher sensitivity is used, can be effected. Thus, the mixture resist follows the optical sensitivity curve, as shown in broken curve, i.e., has a high gamma value. |
