Patent ID: 6146930
Filing Date: 2000-11-14
Classification: H01L

Abstract:
A method for fabricating an active-matrix liquid crystal display integrally formed with a driver circuit wherein a liquid crystal material is sandwiched between a TFT substrate and a counterpart substrate having a counter electrode on an insulating substrate, the TFT substrate comprising an insulative substrate, thin film transistors arranged in a matrix pattern on the insulating substrate and each provided to an individual pixel portion for use as a switching element, and a CMOS driver circuit having a CMOS for driving the thin film transistor of each pixel portion, the method comprising formation of the thin film transistors of each pixel portion and the CMOS including a first conductivity type thin film transistor and a second conductivity type thin film transistor, the formation comprising at least the steps of:(a) sequentially forming a channel semiconductor film, a gate insulating film and a gate electrode thin film on the insulating substrate in regions thereof provided for the thin film transistor of each pixel portion and for the first conductivity type thin film transistor and second conductivity type thin film transistor of the CMOS driver circuit, followed by forming a photoresist on the gate electrode thin film for finely patterning the gate electrode thin film;(b) etching the gate electrode thin film with use of the photoresist as a mask followed by over-etching with use of the same etchant after judging the completion of the gate thin film etching for predetermined time period to form gate electrodes each narrower than the photoresist;(c) after the step of etching the gate electrode thin film, ion-implanting a first conductivity type impurity to a high concentration into source/drain regions lying on opposite sides of each of the gate electrodes with use of the photoresist as a mask to form three kinds of first conductivity type thin film transistors of an offset structure and afterward removing said photoresist; and(d) covering at least the thin film transistor of each pixel portioned the thin film transistor intended for the first conductivity type thin film transistor of the CMOS driver circuit with a photoresist and ion-implanting a second conductivity type impurity into the thin film transistor intended for the second conductivity type thin film transistor of the CMOS driver circuit to a concentration higher than the concentration of the first conductivity type impurity in terms of an effective concentration determined in view of the activation yield of each impurity at the time of completion of the activation thereof, to form the second conductivity type thin film transistor of the CMOS driver circuit.