METAL OXIDE TFT WITH IMPROVED SOURCE/DRAIN CONTACTS
First Claim
1. A method of forming an active layer for a TFT with areas of different carrier densities, the method comprising the steps of:
- providing a substrate with a gate, a layer of gate dielectric adjacent the gate, and a layer of high carrier concentration metal oxide semiconductor material positioned on the gate dielectric opposite the gate; and
oxidizing a channel portion of the layer of metal oxide semiconductor material aligned with the gate to reduce the carrier concentration of the channel portion, contact portions on both sides of the channel portion retaining the high carrier concentration.
9 Assignments
0 Petitions
Accused Products
Abstract
A method of forming ohmic source/drain contacts in a metal oxide semiconductor thin film transistor includes providing a gate, a gate dielectric, a high carrier concentration metal oxide semiconductor active layer with a band gap and spaced apart source/drain metal contacts in a thin film transistor configuration. The spaced apart source/drain metal contacts define a channel region in the active layer. An oxidizing ambient is provided adjacent the channel region and the gate and the channel region are heated in the oxidizing ambient to reduce the carrier concentration in the channel area. Alternatively or in addition each of the source/drain contacts includes a very thin layer of low work function metal positioned on the metal oxide semiconductor active layer and a barrier layer of high work function metal is positioned on the low work function metal.
-
Citations
39 Claims
-
1. A method of forming an active layer for a TFT with areas of different carrier densities, the method comprising the steps of:
-
providing a substrate with a gate, a layer of gate dielectric adjacent the gate, and a layer of high carrier concentration metal oxide semiconductor material positioned on the gate dielectric opposite the gate; and oxidizing a channel portion of the layer of metal oxide semiconductor material aligned with the gate to reduce the carrier concentration of the channel portion, contact portions on both sides of the channel portion retaining the high carrier concentration.
-
-
2. A method of forming ohmic source/drain contacts in a metal oxide semiconductor thin film transistor comprising the steps of:
-
providing a gate, a gate dielectric, a high carrier concentration metal oxide semiconductor active layer with a band gap and spaced apart source/drain metal contacts in a thin film transistor configuration, the spaced apart source/drain metal contacts defining a channel region in the active layer; providing an oxidizing ambient adjacent the channel region; and heating the gate and the channel region in the oxidizing ambient to reduce the carrier concentration in the channel area. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of forming ohmic source/drain contacts in a metal oxide semiconductor thin film transistor comprising the steps of:
-
providing a substrate with a gate, a layer of gate dielectric overlying the gate, and a layer of high carrier concentration metal oxide semiconductor material overlying the gate dielectric opposite the gate; providing an oxidizing ambient adjacent the layer of metal oxide semiconductor material; heating the gate and an adjacent channel area in the metal oxide semiconductor material in the oxidizing ambient to reduce the carrier concentration in the channel area while retaining the high carrier concentration in areas on both sides of the channel area; and forming spaced apart source/drain metal contacts on the metal oxide semiconductor material, the spaced apart source/drain metal contacts being positioned one on each side of the channel region on the high carrier concentration areas in the metal oxide semiconductor material. - View Dependent Claims (16, 17, 18)
-
-
19. An active layer for a TFT with areas of different carrier densities comprising:
-
a substrate with a gate, a layer of gate dielectric adjacent the gate, and a layer of high carrier concentration metal oxide semiconductor material positioned on the gate dielectric opposite the gate; and a channel portion of the layer of metal oxide semiconductor material aligned with the gate oxidized to reduce the carrier concentration of the channel portion, contact portions on both sides of the channel portion retaining the high carrier concentration. - View Dependent Claims (20, 21)
-
-
22. A metal to metal oxide low resistance ohmic contact in a metal oxide semiconductor thin film transistor comprising:
-
a gate, a gate dielectric, a high carrier concentration metal oxide semiconductor active layer with a band gap and spaced apart source/drain metal contacts in a thin film transistor configuration, the spaced apart source/drain metal contacts defining a channel region in the active layer; and portions of the metal oxide semiconductor active layer in contact with the source/drain metal contacts having a carrier concentration greater than a carrier concentration in the channel region. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
-
-
34. A metal to metal oxide low resistance ohmic contact in a metal oxide semiconductor thin film transistor comprising:
-
a gate, a gate dielectric, a high carrier concentration metal oxide semiconductor active layer with a band gap and spaced apart source/drain metal contacts in a thin film transistor configuration; each of the source/drain contacts including a very thin layer of low work function metal positioned on the metal oxide semiconductor active layer, the work function of the low work function metal being one of equal to and lower than a work function of the metal oxide semiconductor active layer; and each of the source/drain contacts including a barrier layer of high work function metal positioned on the low work function metal, the work function of the high work function metal being one of equal to and greater than the work function of the metal oxide semiconductor active layer. - View Dependent Claims (35, 36, 37, 38, 39)
-
Specification