CN100530607C

CN100530607C - Method of producing ZnO based transparent film transistor array

Info

Publication number: CN100530607C
Application number: CNB2007101885642A
Authority: CN
Inventors: 张景文; 张新安; 侯洵; 张�杰
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2007-12-11
Filing date: 2007-12-11
Publication date: 2009-08-19
Anticipated expiration: 2027-12-11
Also published as: CN101183667A

Abstract

The invention discloses a method for preparing transparent ZnO base thin film transistor array, which adopts a preparing process of four times of stripping technology for ZnO base thin film growing using radio frequency magnetron sputtering technique and anneals ZnO base thin film in oxygen to improve electrical properties. The thin film transistor array adopts transparent conductive thin film such as ITO, ZnO:Al or ZnO:Ga to be used as grid, source and drain electrode; thin films such as SiO2, Al2O3 and SiNX are adopted as insulation layer. The transmission of ZnO base thin film transistor array from the test reaches 85% in visible band, which provides a new way for developing plate display array with high performance.

Description

A kind of preparation method of zno-based transparent film transistor array

Technical field

The invention belongs to flat panel display (FPD) technical field, the preparation method who relates to a kind of zno-based transparent film transistor array, adopt the transmitance height of the zno-based transparent film transistor array of this method preparation, provide a kind of new approach for developing high performance flat panel display array at visible light wave range.

Background technology

Arrival along with the information age, active driving flat panel display is used extensive day by day, wherein most typical representative is the LCD (TFT-LCD) of thin-film transistor driving and the organic light emitting diode display (TFT-OLED) that thin-film transistor drives, and thin-film transistor plays crucial effects as a kind of switch element to the performance that improves display device.In order to realize the display device of low-power consumption, fast-response speed, process stabilizing, be that the thin-film transistor of channel layer is widely studied with amorphous silicon, polysilicon and organic semiconductor.But the amorphous silicon film transistor mobility is low, and very strong photoelectric effect is arranged, and influences the charge storage characteristic of liquid crystal pixel.Polycrystalline SiTFT complicated process of preparation, cost height, the silica-base film transistor is opaque at visible light wave range simultaneously, has limited the raising of display unit aperture opening ratio.And organic semiconductor thin film transistor (OTFT) is difficult to overcome shortcomings such as low life-span, low mobility.

Zinc oxide (ZnO) is a kind of wide bandgap compound semiconductor that is widely studied in recent years, in white light-emitting diodes, ultraviolet detector, gas sensor, SAW (Surface Acoustic Wave) device important use is arranged.This material has low, the higher electron mobility of growth temperature, is easy to etching, to advantage such as substrate is less demanding.The someone has reported with the zno-based material to be the thin-film transistor of channel layer recently, and demonstrates excellent electrooptical property.If use zno-based TFT following clear superiority will be arranged as the switch element of driven with active matrix:

1) the zno-based film has higher electron mobility, can improve the response speed of display, satisfies the requirement of high definition, big capacity terminal demonstration;

2) can prepare visible-range has than the bright thin-film transistor of the full impregnated of high permeability, improves the aperture opening ratio of LCD, makes indicator screen more clear bright and cut down the consumption of energy;

3) zno-based growth for Thin Film temperature is low, less demanding to substrate.These can reduce the cost of display, and open up new approach for flexible display device.

Summary of the invention

The objective of the invention is to, a kind of preparation method of zno-based transparent film transistor array is provided, this method has been taked the preparation process of four lithography stripping technology, on substrate, prepare grid, zno-based channel layer, insulating barrier and source, drain electrode respectively, adopted in the high purity oxygen gas method of annealing in process to improve the electrical properties of zno-based film simultaneously.

In order to realize above-mentioned task, the present invention takes following technical solution:

A kind of method for preparing transparent ZnO base tft array is characterized in that comprising the following steps:

Step 1, with simple glass or quartzy as substrate, photoetching gate patterns on substrate is used transparent conductive films such as magnetron sputtering deposition ITO, ZnO:Al or ZnO:Ga then, take out sample in acetone soln ultrasonic several minutes, will remain photoresist lift off and promptly form grid;

Step 2, secondary alignment insulating barrier figure on the ITO grid is with the magnetron sputtering SiO that grows ₂, Al ₂O ₃Film or prepare SiN with chemical vapour deposition technique _XDeng insulating barrier, ultrasonic in acetone equally unnecessary photoresist is partly peeled off;

Step 3 at insulating layer of thin-film glazing ditch road layer pattern, is used the magnetron sputtering ZnO based thin film once more, ultrasonicly in acetone then removes unnecessary photoresist;

Step 4 is with zno-based film annealing in process 1h in 500 ℃ of oxygen atmosphere, to improve its electric property.

Step 5, alignment source, drain electrode figure on the channel layer figure, source-drain electrode adopt the magnetron sputtering method preparation, and material can be selected transparent conductive films such as ITO, ZnO:Al or ZnO:Ga for use, then through promptly obtaining transparent ZnO base tft array after the acetone sonicated.

Method of the present invention can be prepared the zno-based transparent film transistor array, and the complete and existing microelectronic technique of this preparation process is compatible mutually, and whole process of preparation is finished at low temperatures, provides a kind of new approach for developing high performance flat panel display array.

Description of drawings

Fig. 1 is the cross section structure schematic diagram of transparent ZnO-TFT;

Fig. 2 is the picture in kind of the single transparent ZnO-TFT of microscopically shooting;

Fig. 3 is the picture in kind of the transparent ZnO-tft array of preparation on the quartz glass substrate;

Fig. 4 is the output characteristic curve of transparent ZnO-TFT;

Fig. 5 is the transfer characteristic curve of transparent ZnO-TFT;

Fig. 6 is the transmitted spectrum of transparent ZnO-TFT;

The present invention is described in further detail below in conjunction with accompanying drawing.

Embodiment

The present invention is that four lithography stripping technologies of employing and magnetron sputtering technique prepare the zno-based transparent film transistor array, referring to Fig. 1, transparent film transistor is a kind of field effect transistor switch device, concrete structure comprises substrate, grid, insulating barrier, channel layer thin film, source electrode and drain electrode are arranged on the substrate, wherein, if substrate and every layer film all adopt transparent material just can prepare transparent zno-based film tft array, grid and source, drain electrode are generally used films such as ITO, the ZnO:Al of electrically conducting transparent or ZnO:Ga, and insulating barrier can adopt SiO ₂, Al ₂O ₃Deng dielectric film.

Below be the specific embodiment that the inventor provides:

Embodiment 1:

Present embodiment is a preparation ZnO channel layer transparent film transistor array, and concrete implementation step is:

1. photoetching gate patterns on simple glass or quartz substrate then with magnetron sputtering growth ITO transparent conductive film, takes out sample ultrasonic several minutes formation gate patterns in acetone soln, and the grid film thickness is about 200nm;

2, secondary alignment insulating barrier figure on the ITO grid is with the magnetron sputtering SiO that grows ₂Film is as insulating barrier, and ultrasonic in acetone unnecessary photoresist partly peeled off;

3, alignment channel layer figure on insulating layer of thin-film, and magnetron sputtering growing ZnO thin-film ultrasonicly in acetone then removes unnecessary photoresist;

4, with sample annealing in process 1h in 500 ℃ of oxygen atmosphere;

5, alignment source, drain electrode figure on the ZnO channel layer, and with the magnetron sputtering deposition ito thin film as contact electrode, promptly obtain transparent ZnO-tft array through after the acetone sonicated then.

Experiment shows that present embodiment carries out annealing in process to ZnO film in high purity oxygen gas, can improve the electrical properties of ZnO-TFT.

The applicant tests the electrical properties of the transparent ZnO-TFT of preparation, finds that this transistor has good the control function of current and pinch-off behavior.Be operated in the N channel enhancement mode, current on/off ratio is about 10 ⁴, threshold voltage is-0.7V that the field mobility of electronics reaches 15.6cm ²V ^-1s ^-1(Fig. 4, Fig. 5).

Embodiment 2:

Different is for present embodiment and embodiment 1, the ito thin film in step 1 and the step 5 is changed to transparent conductive films such as ZnO:Al or ZnO:Ga, can prepare transparent ZnO-tft array equally.

Embodiment 3:

Different is for present embodiment and embodiment 1, with the SiO in the step 2 ₂Film is changed to HfO ₂, Al ₂O ₃Or Y ₂O ₃Etc. transparent insulating layer of thin-film, other is all with embodiment 1.

Embodiment 4:

Different is for present embodiment and embodiment 1, changes the ZnO target in the step 1 into Zn-Mg-0, Zn-Sn-O or Zn-In-O target, and other is all with embodiment 1.

Claims

1. the preparation method of a transparent ZnO base tft array is characterized in that comprising the following steps:

Step 1, as substrate, photoetching gate patterns on substrate is used magnetron sputtering deposition ITO, ZnO:Al or ZnO:Ga transparent conductive film then with quartz, ultrasonicly in acetone soln will remain photoresist lift off, forms transistorized grid;

Step 2, alignment insulating barrier figure for the second time on transistorized grid is with the magnetron sputtering SiO that grows ₂, Al ₂O ₃Film or prepare SiN with chemical vapour deposition technique _XInsulating barrier ultrasonicly in acetone is partly peeled off unnecessary photoresist, forms the insulating barrier of thin-film transistor;

Step 3, at transistorized insulating layer of thin-film glazing ditch road layer pattern, with magnetron sputtering growing ZnO thin-film, ZnMgO film, Zn-Sn-O film or Zn-In-O film, ultrasonicly in acetone then remove unnecessary photoresist, form the channel layer of thin-film transistor;

Step 4 is with zno-based film annealing in process 1h in 500 ℃ of oxygen atmosphere;

Step 5, alignment source-drain electrode figure on the channel layer figure, source-drain electrode adopt the magnetron sputtering method preparation, and material selection ITO, ZnO:Al or ZnO:Ga transparent conductive film are then through promptly obtaining transparent ZnO base tft array after the acetone sonicated.