Method of manufacturing an electronic device using thermally stable mask

A method of manufacturing an electronic device comprising thin-film circuitry with a semiconductor film having a first portion of higher crystallinity than a second portion, and including the stages of:

• (a) depositing material for the semiconductor film on a substrate,
• (b) forming an insulating layer on the film,
• (c) forming a masking pattern on the insulating layer over the intended second portion of the film,
• (d) exposing the un-masked first portion of the film to an energy beam to crystallise the material in the first portion, while using the masking pattern to mask the second portion from the energy beam, and
• (e) forming thin-film circuit elements with the first and second portions of the film,
• characterised in that the masking pattern comprises thermally-stable inorganic material on the insulating layer, the insulating layer being a barrier layer of sufficient thickness to mask the second portion of the film from heating effects in the inorganic material when the second portion of the film is masked from the energy beam in stage (d), and the masking pattern being formed in stage (c) by steps which include:
• (i) depositing the inorganic material on the barrier insulating layer on the film,
• (ii) using a photoresist pattern for defining the masking pattern in the inorganic material and in the barrier insulating layer by removal of the barrier insulating layer and the inorganic material from the first portion of the film;
• and
• (iii) removing the photoresist pattern before exposing the first portion of the film to the energy beam in stage (d).