CN103247668A

CN103247668A - Thin film transistor

Info

Publication number: CN103247668A
Application number: CN2012100251119A
Authority: CN
Inventors: 曾坚信
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Priority date: 2012-02-06
Filing date: 2012-02-06
Publication date: 2013-08-14

Abstract

A thin film transistor includes a baseplate, as well as an active layer and a grid electrode both arranged on the baseplate, wherein the active layer includes a channel layer, as well as a source electrode and a drain electrode respectively arranged on two opposite sides of the channel layer and electrically connected with the channel layer; the grid electrode is positioned above or below the channel layer; a grid insulating layer is arranged between the grid electrode and the channel layer; the active layer is composed of at least two layers of oxide semiconductors in a stacked manner; and every two adjacent layers of oxide semiconductors are made of different materials, so that influence degree on the oxide semiconductor layers by the manufacture procedure condition can be balanced, and further, better conductivity of the active layer is ensured.

Description

Thin-film transistor

Technical field

The present invention relates to a kind of thin-film transistor.

Background technology

Along with the progress of technology, thin-film transistor has been widely applied among display, with demands such as the slimming that adapts to display and miniaturizations.Thin-film transistor generally comprises parts such as grid and active layer, active layer comprises drain electrode, source electrode and channel layer, thin-film transistor changes the conductivity of channel layer by the voltage of control grid, makes the state that forms conducting or end between source electrode and the drain electrode.

Usually, the active layer of thin-film transistor is generally one deck structure, and adopts IGZO to make material as it.Yet the IGZO material can be subjected to the processing procedure condition effect and change its characteristic, and especially the hole of oxygen atom (Oxygen vacancy) to the influence of conductivity, thereby influences the conductivity of active layer.

Summary of the invention

In view of this, be necessary to provide a kind of thin-film transistor with better conductivity.

A kind of thin-film transistor, comprise substrate, be located at active layer and grid on the substrate, described active layer comprises channel layer and lays respectively at the relative both sides of this channel layer and the source electrode that is electrically connected with this channel layer, drain electrode, this grid is positioned at top or the below of channel layer, be provided with gate insulation layer between grid and the channel layer, described active layer is piled up by two-layer at least oxide semiconductor layer and forms, and every adjacent two-layer oxide semiconductor layer adopts different materials to make.

In thin-film transistor provided by the invention, this active layer is piled up by two-layer at least oxide semiconductor layer and forms, and every adjacent two-layer oxide semiconductor layer adopts different materials to make, under same temperature, between can balanced each oxide semiconductor layer because of the influence degree of process conditions, thereby guarantee that active layer has electric conductivity preferably.

Description of drawings

Fig. 1 is the schematic cross-section of the thin-film transistor that provides of first embodiment of the invention.

Fig. 2 is the schematic cross-section of the thin-film transistor that provides of second embodiment of the invention.

Fig. 3 is the schematic cross-section of the thin-film transistor that provides of third embodiment of the invention.

The main element symbol description

Thin-film transistor	100、100a、100b
		Substrate
	10
		Active layer	20、20b
First oxide semiconductor layer	21、21a、21b
		Channel layer
	22、22a、22b
		Second oxide semiconductor layer	23、23a、23b
Source electrode
		24、24a
Drain electrode
		26、26a
Grid
		30、30b
Source electrode
		40、40a、40b
Drain electrode
		50、50a、50b
Gate insulation layer			60、60b
	Etch stop layer	70

Following embodiment will further specify the present invention in conjunction with above-mentioned accompanying drawing.

Embodiment

As shown in Figure 1, this thin-film transistor 100 comprises substrate 10, is located at active layer 20 and grid 30 on this substrate 10.

This substrate 10 can be made by materials such as glass, quartz, silicon wafer, Merlon, polymethyl methacrylate, metal forming or paper.

This active layer 20 is arranged on the upper surface of substrate 10.In the present embodiment, described active layer 20 is piled up by first oxide semiconductor layer 21 and second oxide semiconductor layer 23 and forms, and first oxide semiconductor layer 21 adopts different materials to make with second oxide semiconductor layer 23.First oxide semiconductor layer 21 and second oxide semiconductor layer 23 can one of them be made by indium oxide gallium zinc (IGZO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), gallium oxide zinc (GZO), tin indium oxide (ITO), gallium oxide tin (GTO), aluminium oxide tin (ATO), titanium oxide (TiOx) or tin oxide (ZnO).In the present embodiment, described first oxide semiconductor layer 21 is located at the top of second oxide semiconductor layer 23, and the energy gap of second oxide semiconductor layer 23 is less than the energy gap of first oxide semiconductor layer 21, and namely the carrier concentration of first oxide semiconductor layer 21 is less than the carrier concentration of second oxide semiconductor layer 23.

This active layer 20 comprises the channel layer 22 that is positioned at substrate 10 upper surface middle part and is separately positioned on the relative both sides of channel layer 22 and source electrode 24 and the drain electrode 26 that electrically connects with channel layer 22.Described source electrode 24 and drain electrode 26 lay respectively at upper left side and the upper right side of channel layer 22, and and substrate 10 between maintain a certain distance.Because this active layer 20 is formed by first oxide semiconductor layer 21 and second oxide semiconductor layer, 23 folded establishing, and can utilize multiple interface enhancing oxide semiconductor layer to the resistivity of the influence of external environment condition; And first oxide semiconductor layer 21 adopts different material manufacturings to form respectively with second oxide semiconductor layer 23, and the two-dimentional conducting particles that forms between can the oxide by different energy gaps increases the conductivity of active layer 20.Compare with the active layer that existing employing homogenous material is made, thin-film transistor of the present invention under specified temp, can balanced each

oxide semiconductor layer

21,23 between because of the influence degree of process conditions, thereby guarantee that active layer 20 has electric conductivity preferably.

This thin-film transistor 100 also comprises respectively and source electrode 24 and drain 26 source electrodes that are electrically connected 40 and drain electrode 50.In the present embodiment, described source electrode 40 and drain electrode 50 are located at the upper surface of substrate 10 respectively and are laid respectively at the relative both sides of channel layer 22, source electrode 40 is arranged between second oxide semiconductor layer 23 of substrate 10 and source electrode 24, and drain electrode 50 is arranged between second oxide semiconductor layer 23 of substrate 10 and drain electrode 26.The thickness of described source electrode 40 and drain electrode 50 is less than the thickness of channel layer 22.Described source electrode 40 is used for being connected with extraneous power supply with drain electrode 50, for thin-film transistor 100 operate as normal provide corresponding driving voltage.In this thin-film transistor 100, because source electrode 40 and drain electrode 50 all contact with the outer surface of little second oxide semiconductor layer 23 of energy gap in the active layer 20, be source electrode 40 and drain electrode 50 all with active layer 20 in the outer surface of high second oxide semiconductor layer 23 of carrier concentration contact or form electric connection, thereby have electric conductivity preferably.

Grid 30 is positioned at the top of channel layer 22, is formed with gate insulation layer 60 between grid 30 and the channel layer 22.Whether thin-film transistor 100 at channel layer 22 forms conductive channel by apply different voltage at grid 30 with control in when work, thus the conducting of control thin-film transistor 100 or end.In general, for the thin-film transistor 100 of enhancement mode, when not applying voltage on the grid 30, do not form conductive channel on the channel layer 22, thin-film transistor 100 is in cut-off state; When grid 30 applies a certain size voltage, will be owing to effect of electric field form conductive channel to connect source electrode 24 and drain electrode 26 in the channel layer 22, this moment, thin-film transistor 100 was in conducting state.Concerning the thin-film transistor 100 of depletion type, when not applying voltage on the grid 30, be formed with conductive channel on the channel layer 22, thin-film transistor 100 is in conducting state; When grid 30 applies a certain size voltage, the conductive channel on the channel layer 22 will disappear owing to effect of electric field, and this moment, thin-film transistor 100 was in cut-off state.In the present embodiment, the making material of grid 30 comprises gold, silver, aluminium, copper, chromium, molybdenum, titanium or its alloy.The making material of gate insulation layer 60 comprises the oxide S iOx of silicon, and the nitride SiNx of silicon or the nitrogen oxide SiONx of silicon, or the insulating material of other high-ks are as Ta ₂O ₅Or HfO ₂

Fig. 2 is the schematic cross-section of the thin-film transistor 100a of second embodiment of the invention, and the difference of present embodiment and last embodiment is: the described second oxide semiconductor layer 23a is located at the top of the first oxide semiconductor layer 21a; Described source electrode 24a and drain electrode 26a are positioned on the upper surface of substrate 10, and lay respectively at the relative both sides of channel layer 22a, and the end face of described source electrode 24a and drain electrode 26a is all mutually concordant with the end face of channel layer 22a.Described source electrode 40a and drain electrode 50a be the local surface that covers the second oxide semiconductor layer 23a of the second oxide semiconductor layer 23a of source electrode 24a and the 26a that drains respectively, and another part extends on substrate 10 surfaces.

Fig. 3 is the schematic cross-section of the thin-film transistor 100b of third embodiment of the invention, the difference of present embodiment and second embodiment is: described grid 30b is positioned at the below of active layer 20b, gate insulation layer 60b is located between this active layer 20b and the grid 30b, it is the central area that grid 30b directly is located at substrate 10 surfaces, gate insulation layer 60b is covered in the surface of grid 30b, active layer 20b is located at the surface of gate insulation layer 60b, described active layer 20b is alternately folded to establish by a plurality of first oxide semiconductor layer 21b and the second oxide semiconductor layer 23b and forms, and also is provided with an etch stop layer 70 on the surface of channel layer 22b.The making material of this etch stop layer 70 be selected from SiOx, AlOx, HfOx, YOx and SiNx one of them.Because be separated with etch stop layer 70 between between source electrode 40b and drain electrode 50b and the channel layer 22b, the metallic atom of source electrode 40b and drain electrode 50b is not easy to diffuse to channel layer 22b by diffusion or electron transfer.Therefore, the electrical property of thin-film transistor 100b is not easy to be subjected to the metallic atom diffusion of source electrode 40b or drain electrode 50b or the influence of electron transfer.

During concrete enforcement, described thin-film transistor 100,100a, the structure of 100b is not limited to the situation of above-described embodiment, described

active layer

20,20b can be by two-layer, folded the establishing of three layers or multilayer forms, it can be by the first different oxide semiconductor layer 21 of energy gap, 21a, 21b and second

oxide semiconductor layer

23,23a, 23b alternately folded establishing forms, also can be formed by folded the establishing of the different oxide semiconductor layer of multiple energy gap, and guarantee source electrode 40 in each execution mode, 40a, 40b and

drain electrode

50,50a, 50b all contacts or forms electric connection with the surface of the oxide semiconductor layer of energy gap minimum.Described

grid

30,30b can be located at the top of

channel layer

22,22a, 22b, also can be located at the below of

channel layer

22,22a, 22b, as long as guarantee that

gate insulation layer

60,60b are between

grid

30,30b and

channel layer

22,22a, 22b.When

grid

30,30b are positioned at the below of

channel layer

22,22a, 22b, can be provided with etch stop layer 70 in

channel layer

22,22a, 22b, also can not be provided with this etch stop layer 70.

Be understandable that, for the person of ordinary skill of the art, can make change and the distortion that other various pictures are answered by technical conceive according to the present invention, and all these change the protection range that all should belong to claim of the present invention with distortion.

Claims

1. thin-film transistor, comprise substrate, be located at active layer and grid on the substrate, described active layer comprises channel layer and lays respectively at the relative both sides of this channel layer and the source electrode that is electrically connected with this channel layer, drain electrode, this grid is positioned at top or the below of channel layer, be provided with gate insulation layer between grid and the channel layer, it is characterized in that: described active layer is piled up by two-layer at least oxide semiconductor layer and forms, and every adjacent two-layer oxide semiconductor layer adopts different materials to make.

2. thin-film transistor as claimed in claim 1 is characterized in that: the material of each of described active layer layer be selected from IGZO, IZO, AZO, GZO, ITO, GTO, ATO, TiOx and ZnO one of them.

3. thin-film transistor as claimed in claim 1 or 2, it is characterized in that: also comprise respectively the source electrode and the drain electrode that are electrically connected with source electrode and drain electrode, described source electrode and drain electrode respectively with active layer in the oxide semiconductor layer electric connection of energy gap minimum.

4. thin-film transistor as claimed in claim 1, it is characterized in that: described active layer is alternately piled up by first oxide semiconductor layer and second oxide semiconductor layer and forms.

5. thin-film transistor as claimed in claim 4, it is characterized in that: the energy gap of described second oxide semiconductor layer is less than the energy gap of first oxide semiconductor layer.

6. thin-film transistor as claimed in claim 4, it is characterized in that: the carrier concentration of described second oxide semiconductor layer is greater than the carrier concentration of first oxide semiconductor layer.

7. thin-film transistor as claimed in claim 5 is characterized in that: also comprise the source electrode and the drain electrode that are electrically connected with source electrode and drain electrode respectively, described source electrode and drain electrode electrically connect with second oxide semiconductor layer respectively.

8. thin-film transistor as claimed in claim 1 is characterized in that: described active layer is piled up by the oxide semiconductor layer of multiple different material and forms.

9. thin-film transistor as claimed in claim 1, it is characterized in that: described channel layer is provided with etch stop layer, and described source electrode and drain electrode cover on the part surface of etch stop layer.