Array testing method using electric bias stress for TFT array
View Patent ↗A method of detecting thin film transistor (TFT) defects in a TFT-liquid crystal display (LCD) panel, includes, in part, applying a stress bias to the TFTs disposed on the panel; and detecting a change in electrical characteristics of the TFTs. The change in the electrical characteristics of the TFTs may be detected using a voltage imaging optical system or an electron beam. The panel temperature may be varied while the bias stress is being applied. The change in the electrical characteristics is optionally detected across an array of the TFTs.
1. A method for detecting thin film transistor (TFT) defects in a TFT-liquid crystal display (LCD) panel, the method comprising:
applying a stress bias to the TFTs disposed on the panel to cause a change in a threshold voltage or off current of one or more of the TFTs;
terminating the stress bias;
applying test signals to the TFTs; and
detecting the change in the threshold voltage or off current of the one or more of the TFTs in response to the applied test signals.
2. The method of claim 1 wherein the change in the threshold voltage or off current of the one or more of the TFTs is detected using a voltage imaging optical system.
3. The method of claim 1 wherein the change in the threshold voltage or off current of the one or more of the TFTs is detected using an electron beam.
4. The method of claim 1 further comprising:
changing a temperature of the panel while applying the stress bias.
5. The method of claim 4 further comprising:
heating the panel while applying the stress bias.
6. The method of claim 4 further comprising:
cooling the panel while applying the stress bias.
7. The method of claim 1 further comprising:
changing a temperature of the panel while detecting a change in the threshold voltage or off current of the one or more of the TFTs.
8. The method of claim 7 further comprising:
heating the panel while detecting a change in the threshold voltage or off current of the one or more of the TFTs.
9. The method of claim 7 further comprising:
cooling the panel while detecting a change in the threshold voltage or off current of the one or more of the TFTs.
10. The method of claim 1 wherein said TFTs are disposed in an array, the method further comprising:
detecting a changes in the threshold voltage or off current of the one or more of the array of TFTs.