1. Field of the Invention
The present invention relates to the image display field, and more particular to an IGZO transistor structure and manufacturing method for the same.
2. Description of Related Art
The thin-film field-effect transistor (TFT) based on oxide semiconductor is a hot spot for the display field in the future, and in recent years, it has been widely studied and developed. Wherein, the amorphous indium gallium zinc oxide (a-IGZO) compound film as the active channel has a high mobility up to 80 cm2/Vs (the mobility of the amorphous silicon (a-Si) is only 0.5˜0.8 cm2/Vs), and it is compatible with the large scale and mass production process for the a-Si. Therefore, the indium gallium zinc oxide (IGZO) semiconductor has potential application for next-generation LCD and organic light emitting diode (OLED).
When a metal is contacting with IGZO, the semiconductor energy band at the interface is bend, which forms the potential barrier. The existence of the potential barrier will result in a large interface resistance, i.e., the Schottky contact. The Schottky resistance will cause insufficient current at on-state of a TFT component and too large sub-threshold swing, and decreasing the stability of the component in order to affect the display quality. Therefore, to reduce the contact resistance of the metal and the IGZO to form the ohmic contact is an important factor in determining the quality a semiconductor element. One way to form a good ohmic contact with the semiconductor region is performing heavy doping at the semiconductor region contacted with the metal such that the depletion region of the interface is narrowed and the electrons have more opportunities for direct tunneling (tunneling effect)
FIG. 1 shows a standard top-gate-bottom-contact structure for a TFT, and includes a substrate 1′, a source electrode 2′, a drain electrode 3′, a gate electrode 4′, an insulation layer 5′, and an IGZO layer 6′. FIG. 2 is a schematic diagram of the top-gate-bottom-contact structure through heavy doping, wherein a contact region of the source/drain electrodes and IGZO layer 6′ forms a n+IGZO region 7′.
However, in the conventional manufacturing method, in particular by the method of plasma treatment to perform the N-type doping on IGZO layer, it ignores the protection of the channel of the IGZO layer so that it is easily damage the channel of the IGZO layer in order to affect the performance of the ohmic contact.