Semiconductor electronic devices and methods of manufacture thereof
A method of manufacturing an electronic device comprises: providing a layer of semiconductor material comprising a first portion, a second portion, and a third portion, the third portion connecting the first portion to the second portion and providing a semiconductive channel for electrical current flow between the first and second portions; providing a gate terminal arranged with respect to said third portion such that a voltage may be applied to the gate terminal to control an electrical conductivity of said channel; and processing at least one of the first and second portions so as to have an electrical conductivity greater than an electrical conductivity of the channel when no voltage is applied to the gate terminal. In certain embodiments, the processing comprises exposing at least one of the first and second portions to electromagnetic radiation. The first and second portions may be laser annealed to increase their conductivities.
1. A method of manufacturing an electronic device, the method comprising:
providing a layer of semiconductor material comprising a first portion, a second portion, and a third portion, the third portion connecting the first portion to the second portion and providing a semiconductive channel for electrical current flow between the first and second portions;
providing a gate terminal arranged with respect to said third portion such that application of a voltage to the gate terminal controls an electrical conductivity of said channel;
processing at least one of the first and second portions so as to have an electrical conductivity greater than an electrical conductivity of the channel when no voltage is applied to the gate terminal,
wherein said processing comprises exposing at least one of the first and second portions to electromagnetic radiation, and
providing a layer of electrically insulative material covering at least the first and second portions,
wherein said processing comprises exposing at least one of the first and second portions to said electromagnetic radiation through said layer of electrically insulative material; and
wherein providing said gate terminal comprises forming a covering of resist material over the layer of semiconductor material, forming a window in said covering to expose said third portion, depositing a layer of dielectric material at least inside said window to cover said third portion, depositing a layer of conductive material at least inside said window to cover the layer of dielectric material inside the window, and removing remaining material of said covering of resist material so as to expose the first and second portions of the layer of semiconductor material, whereby the layer of conductive material covering the layer of dielectric material covering the third portion provides said gate terminal.
2. A method in accordance with claim 1 , wherein forming said window comprises forming a depression in the covering of resist material and then removing resist material at least from a base of said depression to expose said third portion.
3. A method in accordance with claim 2 , wherein forming said depression comprises forming said depression by imprinting, for example by imprinting with an imprint tool having a plurality of imprint features, each feature being adapted to produce a respective depression having a respective depth.
4. A method in accordance with claim 1 , wherein said window is arranged to have a width greater than a width of the third portion such that said window extends beyond edges of the third portion.
5. A method in accordance with claim 1 , further comprising forming an undercut in said window before forming said layer of dielectric material.
6. A method in accordance with claim 1 , further comprising forming an undercut in said window after forming said layer of dielectric material so as to expose at least one further portion of the surface of the semiconductor layer adjacent the layer of dielectric material inside the window.
7. A method in accordance with claim 5 , further comprising extending said undercut after forming said layer of dielectric material so as to expose at least one further portion of the surface of the semiconductor layer adjacent the layer of dielectric material inside the window.