Field effect transistor manufacturing method

Abstract

Provided is a novel method for manufacturing a field effect transistor. Prior to forming an amorphous oxide layer on a substrate, ultraviolet rays are irradiated onto the substrate surface in an ozone atmosphere, plasma is irradiated onto the substrate surface, or the substrate surface is cleaned by a chemical solution containing hydrogen peroxide.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method for manufacturing a field effect transistor.[0003]2. Related Background Art[0004]In recent years, flat image display devices (Flat Panel Display: FPD) have been developed for practical use as a result of the progress made in technologies such as liquid crystals and electroluminescence (EL). These FPDs are driven by the active matrix circuitry of field effect thin-film transistors (Thin Film Transistor: TFT) which use an amorphous silicon thin-film or a polycrystalline thin-film on a glass substrate in the active layer.[0005]Meanwhile, testing is being carried out into the use of resin substrates which are light-weight and flexible in place of a glass substrate in order to make such FPDs even thinner, lighter and have better their shatter resistance.[0006]However, the manufacture of such an above-described transistor which uses a silicon thin-film requires a relatively high tempe...

AI Technical Summary

Benefits of technology

The present invention provides a method for manufacturing a field effect transistor with improved performance. The method involves a deposition pre-treatment and a deposition post-treatment, which can include steps of irradiating the substrate with ultraviolet rays or plasma, or cleaning the substrate surface with a chemical solution containing hydrogen peroxide. The method can also involve thermal processing at a higher temperature than the deposition temperature of the active layer. The invention also includes a method for forming an active layer comprising an amorphous oxide by resistance heating deposition, electron beam deposition, chemical vapor deposition, line-beam laser deposition, or electrodeposition. The substrate temperature during the deposition can be set at 70° C. or more. The amorphous oxide produced in the invention has an electron carrier density of less than 1×1018 / cm3 or is an oxide where electron mobility tends to increase as electron carrier density increases. The invention also includes a separate step between the first and second steps, and the use of an amorphous oxide containing In, Zn, or Sn, or an oxide containing In, Zn, or Ga.

Problems solved by technology

However, the manufacture of such an above-described transistor which uses a silicon thin-film requires a relatively high temperature thermal process, whereby direct formation onto a resin substrate, which usually has a low thermal resistance, is difficult.

Images