THIN FILM TRANSISTORS HAVING MULTIPLE DOPED SILICON LAYERS
First Claim
1. A thin film transistor fabrication method, comprising:
- depositing an amorphous silicon layer over a substrate having a gate electrode and a gate dielectric layer formed thereon;
depositing two or more doped silicon layers over the amorphous silicon layer, each doped silicon layer having at least one characteristic that is different than the other doped silicon layers;
depositing a metal layer over the two or more doped silicon layers;
patterning the metal layer to form a source electrode and a drain electrode;
patterning the two or more doped silicon layers to expose the amorphous silicon layer; and
depositing a passivation layer over the source electrode, the drain electrode and the exposed amorphous silicon layer.
1 Assignment
0 Petitions
Accused Products
Abstract
Embodiments of the present invention generally relate to a TFT and a method for its fabrication. The TFT disclosed herein is a silicon based TFT in which the active channel comprises amorphous silicon. Over the amorphous silicon, multiple layers of doped silicon are deposited in which the resistivity of the doped silicon layers is higher at the interface with the amorphous silicon layer as compared to the interface with the source and drain electrodes. Alternatively, a single doped silicon layer is deposited over the amorphous silicon in which the properties of the single doped layer change throughout the thickness. It is better to have a lower resistivity at the interface with the source and drain electrodes, but lower resistivity usually means less substrate throughput. By utilizing multiple or graded layers, low resistivity can be achieved. The embodiments disclosed herein include low resistivity without sacrificing substrate throughput.
-
Citations
20 Claims
-
1. A thin film transistor fabrication method, comprising:
-
depositing an amorphous silicon layer over a substrate having a gate electrode and a gate dielectric layer formed thereon; depositing two or more doped silicon layers over the amorphous silicon layer, each doped silicon layer having at least one characteristic that is different than the other doped silicon layers; depositing a metal layer over the two or more doped silicon layers; patterning the metal layer to form a source electrode and a drain electrode; patterning the two or more doped silicon layers to expose the amorphous silicon layer; and depositing a passivation layer over the source electrode, the drain electrode and the exposed amorphous silicon layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A thin film transistor fabrication method, comprising:
-
depositing an amorphous silicon layer over a substrate having a gate electrode and a gate dielectric layer formed thereon; depositing a first doped silicon layer having a first resistivity on the amorphous silicon layer at a first deposition rate; depositing a second doped silicon layer having a second resistivity less than the first resistivity on the first doped silicon layer, the second doped silicon layer deposited at a second deposition rate less than the first deposition rate; depositing a metal layer over the second doped silicon layer; patterning the metal layer to form a source electrode and a drain electrode; patterning the first doped silicon layer and the second doped silicon layer to expose the amorphous silicon layer; and depositing a passivation layer over the source electrode, the drain electrode and the exposed amorphous silicon layer. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. A thin film transistor fabrication method, comprising:
-
depositing an amorphous silicon layer over a substrate having a gate electrode and a gate dielectric layer formed thereon; depositing a doped silicon layer on the amorphous silicon layer, the doped silicon layer having a resistivity that decreases from a first surface in contact with the amorphous silicon layer to a second surface opposite the first surface; depositing a metal layer on the second surface of the doped silicon layer; patterning the metal layer to form a source electrode and a drain electrode; patterning the doped silicon layer to expose the amorphous silicon layer; and depositing a passivation layer over the source electrode, the drain electrode and the exposed amorphous silicon layer. - View Dependent Claims (19, 20)
-
Specification