Disclosure of Invention
The embodiment of the invention provides a thin film transistor which can improve current drive without seriously influencing breakdown voltage.
The application discloses a thin film transistor, including substrate, grid, at least one auxiliary electrode, insulating layer, semiconductor layer, source electrode and drain electrode, the grid with at least one auxiliary electrode locates the interval of substrate surface sets up, the insulating layer covers substrate, grid and at least one auxiliary electrode, semiconductor layer is located on the insulating layer, and orthographic projection covers the grid with at least one auxiliary electrode, the source electrode is connected with the drain electrode the relative both sides of semiconductor layer form the channel region, and at least one auxiliary electrode with the drain electrode is connected.
Wherein a size of a spacing between the at least one auxiliary electrode and the gate electrode is inversely related to an output current.
Wherein the auxiliary electrode is one, and a separation distance between the auxiliary electrode and the gate electrode is greater than zero.
The auxiliary electrodes are arranged on one side of the grid at intervals.
Wherein a width dimension of the auxiliary electrode adjacent to the gate electrode is positively correlated with an amount of output current.
Wherein the at least one auxiliary electrode and the gate electrode are formed in the same process step.
Wherein the at least one auxiliary electrode is connected with the drain electrode through a via hole.
And a circuit for supplying power to the at least one auxiliary electrode is arranged on the thin film crystal.
The device with the thin film transistor comprises the thin film transistor.
The thin film transistor is provided with the auxiliary electrode in the offset area and connected with the drain electrode, the auxiliary electrode induces free charges in the semiconductor layer, and therefore resistance of a semiconductor in the offset area of the drain electrode is reduced, electric field distribution is optimized, and current driving capacity is improved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The application provides a thin film transistor and a device having the same. The thin film transistor is of a high-voltage offset drain structure. Such devices with thin film transistors include, but are not limited to, printing, scanning devices, micro-electro-mechanical systems, planar X-ray sources, and the like.
Referring to fig. 1, the thin film transistor described herein includes a substrate 10, a gate 11, at least one auxiliary electrode 12, an insulating layer 13, a semiconductor layer 14, a source 15, and a drain 16, where the gate 11 and the at least one auxiliary electrode 12 are disposed on a surface of the substrate 10 at intervals, the insulating layer 13 covers the substrate 10, the gate 11, and the at least one auxiliary electrode 12, the semiconductor layer 14 is disposed on the insulating layer 13, and covers the gate 11 and the at least one auxiliary electrode 12 in an orthographic projection manner, the source 15 and the drain 16 are connected to opposite sides of the semiconductor layer 14 to form a channel region, and the at least one auxiliary electrode 12 is connected to the drain 16.
Specifically, the thin film transistor of the present application is an offset drain structure, and is located below the semiconductor layer 14, the gate 11 is located at a position where the channel region is offset from the source 15, and a distance between the gate 11 and the drain 16 is long; the auxiliary electrode 12 is located within the offset region near the drain 16. The gate electrode 11 is located at the same layer as the at least one auxiliary electrode 12. The at least one auxiliary electrode is connected to the drain 16 by a via hole, which is provided in the periphery of the channel region. According to the design requirement, a circuit (not shown) for supplying power to the auxiliary electrode can be arranged on the thin film crystal.
Further, the size of the space between the at least one auxiliary electrode 12 and the gate electrode 11 is inversely related to the output current. In this embodiment, the number of the auxiliary electrodes 12 is one, and the distance S between the auxiliary electrodes 12 and the gate 11 is greater than zero. That is, a space is required between the auxiliary electrode 12 and the gate electrode 11, and after power is applied, the smaller the space S, the larger the electric field in the channel region, the larger the current, but the smaller the breakdown voltage, and the optimal value of S can be determined according to the specific application.
In the prior art, the resistance of a semiconductor layer in an offset region of a high-voltage thin film transistor is very high, the high voltage on a drain electrode mainly falls on an offset structure, the degree between a grid electrode and the drain electrode in the offset region is relatively large, and the resistance of the semiconductor layer is very high; the thin film transistor is provided with the auxiliary electrode 12 in the offset region, and when the thin film transistor works normally, the auxiliary electrode 12 induces free charges in the semiconductor layer 14, so that the resistance of the semiconductor in the offset region of the drain electrode 16 is reduced, the electric field distribution is optimized, the current is increased, and the current driving capability of the thin film transistor is improved. Meanwhile, since the auxiliary electrode 12 is connected to the drain electrode 16, there is no parasitic capacitance therebetween.
Referring to fig. 2, in another embodiment, the plurality of auxiliary electrodes are disposed at an interval at one side of the gate 11. Specifically, the auxiliary electrodes include a first auxiliary electrode 121, a second auxiliary electrode 122, and a third auxiliary electrode 123. The arrangement of the plurality of auxiliary electrodes in the offset region is beneficial to improving the high output current and breakdown voltage of the thin film transistor.
Further, the width dimension of the auxiliary electrode 121 adjacent to the gate electrode 11 is positively correlated with the amount of output current. In this embodiment, the larger the width of the first auxiliary electrode 121 near the gate electrode 11, the larger the output current.
The first auxiliary electrode 121, the second auxiliary electrode 122 and the third auxiliary electrode 123 are disposed at intervals and have spacings S1 and S2, the vertical spacing between the third auxiliary electrode 123 and the drain is S3, and the smaller the distance between the first auxiliary electrode 121 close to the gate 11 and the gate 11 is, the larger the current is; in addition, the area between the first auxiliary electrode 121 and the gate electrode 11 is small, so that the parasitic capacitance is very small.
Please refer toFig. 3 and fig. 4 are graphs of current transfer curves and graphs of electric field distribution curves of the gate surface in the source-drain direction under the condition of the plurality of auxiliary electrodes, where the novel structures 1 to 5 in the graphs are different embodiments of the present invention and implementation manners that are simply changed according to the present invention, such as changes in the number of auxiliary electrodes. As can be seen from fig. 3, the drain current ID of the thin film transistor adopting the offset drain structure of the present application is smaller than the ID of the thin film transistor of the conventional structure by more than two orders of magnitude; as can be seen from fig. 4, the highest electric field (located near the right edge of the gate, which determines the breakdown voltage of the high voltage tft) of the tft with the offset drain structure is approximately an order of magnitude smaller than that of the tft with the conventional tft structure. As can be seen from FIGS. 3 and 4, the introduction of the auxiliary electrode enables the I of the high voltage thin film transistorDThe breakdown voltage of the thin film transistor is almost consistent with that of a high-voltage thin film transistor with an offset drain structure, and the current driving capability is greatly increased, so that the current driving capability of the thin film transistor is ensured, and higher breakdown voltage is maintained.
Further, the at least one auxiliary electrode 12 and the gate 11 are formed in the same process step. Since the auxiliary electrode 12 is formed simultaneously with the gate electrode 11, signal lines and manufacturing steps of the thin film transistor are not increased.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.