[polysilicon thin film transistor and method of forming the same]
AssigneeAu Optronics Corporation
InventorsKUN-HONG CHEN, CHINWEI HU
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Abstract
A polysilicon thin film transistor and a method of forming the same is provided. A poly-island layer is formed over a substrate. A gate insulation layer is formed over the poly-island layer. A gate is formed over the gate insulation layer. Using the gate as a mask, an ion implantation of the poly-island layer is carried out to form a source/drain region in the poly-island layer outside the channel region. An oxide layer and a silicon nitride layer, together serving as an inter-layer dielectric layer, are sequentially formed over the substrate. Thickness of the oxide layer is thicker than or the same as (thickness of the nitride layer multiplied by 9000 Å)1/2 and maximum thickness of the nitride layer is smaller than 1000 Å.
Claims8
A polysilicon thin film transistor, comprising:
- a poly-island layer;
- a gate over the poly-island layer;
- a gate insulation layer between the gate and the poly-island layer;
- and
- an inter-layer dielectric layer, wherein the inter-layer dielectric layer includes an oxide layer and a nitride layer, the oxide layer covers the gate and the gate insulation layer and the nitride layer is over the oxide layer, the oxide layer and the nitride layer of the inter-layer dielectric layer have a thickness relationship given by the following inequality:
- Tox #(TnitrideX 9000 Å)1/2, where Tox represents the thickness of the oxide layer (in Å), Tnitride represents thickness of the silicon nitride layer and that thickness of the nitride layer is between 50 Å and 1000 Å.
A method of forming a polysilicon thin film transistor, comprising the steps of:
- forming a poly-island layer over a substrate;
- forming a gate insulation layer over the poly-island layer;
- forming a gate electrode over the gate insulation layer above a section of the poly-island layer destined for forming a channel region;
- conducting an ion implantation of the poly-island layer using the gate as a mask to form source/drain regions in the poly-island layer outside the channel region;
- and
- sequentially forming an oxide layer and a nitride layer over the substrate to cover the gate and the gate insulation layer, wherein the oxide layer and the nitride layer of the inter-layer dielectric layer have a thickness relationship given by the following inequality:
- Tox #(TnitrideX 9000 Å)1/2, where Tox represents the thickness of the oxide layer (in Å), Tnitride represents thickness of the silicon nitride layer and that thickness of the nitride layer is between 50 Åand 1000 Å.
Dependencies are inferred from the claim text.