Patent ID: 6429058
Filing Date: 2002-08-06
Classification: H01L

Abstract:
A method for opening resist in raised areas of a trilayer thin film transistor device, comprising the steps of:forming a conductive layer over a channel insulator layer to form a raised portion which includes a height above a substantially planar surrounding area, the channel insulator layer being aligned to a gate electrode; forming a photoresist layer on the conductive layer over the raised portion and the surrounding area; patterning the photoresist by employing a gray scale light mask having a gray-scale density pattern with symmetrical two-dimensional holes to reduce exposure light on the photoresist over the raised portion such that after developing the photoresist, the photoresist is reduced over a top surface and a portion of sides of the raised portion but remains in the surrounding area; non-selectively etching the photoresist such that substantially no photoresist remains over the top surface of the top insulator but a reduced thickness of resist remains on adjacent regions including a portion of sides of the raised portion; and etching the conductive layer in accordance with the photoresist to form source and drain electrodes which are self aligned to the channel insulator layer.