CN103035569A - Growth process of thin film transistor - Google Patents

Abstract

The invention provides an In203Ga203CaOZnO (IGCZO) growth process of thin film transistor (TFT) and a tape out process of the TFT. The IGCZO growth process includes the following steps: (1)corroding indium tin oxide (ITO) glass and (2) growing an IGCZO composite coating structure, wherein the prepared procedure of a TFT device of the IGCZO composite coating in the later period includes the following steps: (1) etching aluminium (Al) and (2) etching of the ICGZO with a wet process. In the TFT tape out process, people need to pay attention to the growth process of the IGCZO in an active layer so as to reduce defects of materials, optimize performance of channel conduction and control growth size of the ICGZO of a railing insulating layer, and therefore the TFT device with a low driving voltage and a high switch ratio is achieved.

Description

A kind of thin-film transistor growth technique

Technical field

The present invention relates to IGCZO TFT growth technique and TFT flow technique.

Background technology

A-Si:H TFT is widely used in TFT-LCD as the active switch device.But, the shortcoming of the maximum of a-Si:H TFT is that field-effect mobility is low, simultaneously because the forbidden band of a-Si is narrow, so that it is opaque in visible-range, this range of application, especially a-si:H TFT that has just limited greatly a-si:H TFT can not be used for making start-up circuit, and TFT-LCD needs the peripheral drive circuit of configure dedicated, improve manufacturing cost, reduced reliability.

The transparent semiconductor oxide as the prerequisite of switching device be energy gap greater than 3eV, have high conductivity and high light transmission rate (〉 80%).The wide bandgap semiconductor BaN that other are transparent and SiC also have research to be used for TFT at present.But the wide bandgap semiconductor oxide has more real prospect, because they can be grown at low temperatures, the selection of substrate will be more like this, comprise glass and organic substance.In all oxide semiconductor materials, ZnO leads widely and is paid close attention to owing to the characteristic with low-temperature epitaxy and high electricity.The ZnO structures shape Fujian threshold voltage of TFT device and the quality of characteristics of electrical conductivity thereof.Semiconductor ZnO film material is strong N-shaped, carrier concentration can reach 1020/cm3, the single crystal ZnO mobility can reach 200cm2/Vs, is conducive to form the depletion mode fet that majority carrier is electronics, has naturally utilized electron mobility to be higher than the superiority of hole mobility.But enhancement mode TFT has better prospect at low-power consumption type semiconductor device.Adopt different growing technologies, the ZnO growth temperature is selected can be between 300-700 ℃.The hall mobility of polycrystalline ZnO material is at 10-50cm2/Vs.Also there is recently p-type ZnO to grow by MBE, magnetron sputtering growth and the successful report of combined beam deposition.Based on above characteristics, select ZnO to be subject to extensive concern as the active layer of TTFT.

One of them challenge that zno-based FET development faces is the control of active layer charge carrier.The carrier concentration that unannealed ZnO performance is high, high carrier concentration is so that raceway groove also is in conducting state when making alive not, and device is operated under the spent condition, so intrinsic ZnO device is depletion device.But the realization of high concentration carrier depletion is very difficult, and the enhancement device of being led by applied voltage control electricity has more practical value.ZnO can form the IGCZO alloy material with Ga2O3, In2O3 and CaO, can effectively increase energy gap by the content of regulating Ca among the IGCZO, reduces carrier concentration.Another challenge of zno-based TFT development is the selection of gate dielectric layer.The same with the body silicon device, the leakage current of grid also is must problems of concern.At present the many of usefulness is Si3N4 and HfO2.Direct continuous growth IGCZO film on ito glass has unrivaled advantage at the aspects such as interface of growth control, cost and the device thereof of TFT device.The mobility of electronics is relevant with the local density of state in the energy gap in the IGCZO film, and the distribution of the local density of state is closely related with the thin film technology process conditions.Therefore the selection and optimization of processing step, condition is most important.

Summary of the invention

The invention provides a kind of IGCZO TFT growth technique and TFT flow technique

This IGCZO growth technique comprises:

1) corrosion ito glass;

2) growth IGCZO lamination layer structure

Wherein, IGCZO composite bed TFT device later stage preparation flow is as follows:

1) etching Al;

2) wet etching IGCZO.

Above-mentioned corrosion ito glass comprises and uses corrosive liquid HNO3:H20:HCI=1:2:3,50 ℃ of water-baths 1 minute.

Above-mentioned growth IGCZO lamination layer structure comprises employing physical evaporation low temperature depositing (PELD) the evaporation oxidation thing ZnO of system and Ga2O3, In2O3 and Ca2O3, successive sedimentation growth IGCZO and C-IGCZO composite bed film on the ito glass substrate.

Above-mentioned wet etching IGCZO comprises the 60 ℃ of wet etching IGCZO of solution water-bath that adopt the H3PO4:H2O proportioning.

Embodiment

The invention provides a kind of IGCZO TFT growth technique.

The preparation of 1 material

1) corrosion ito glass

The TIO glass front is coated with the positive glue of 6809#, 4000 rev/mins of whirl coatings 30 seconds, and photoresist thickness is 0.88 micron behind the whirl coating.80 ℃ of front bakings 20 minutes; Photolithographic exposure 12 seconds developed 6 seconds, and microscopy is observed and developed fully, and it is remaining that equipment for burning-off photoresist by plasma bottoming film was removed photoresist in skilful second.120 ℃ in the solid glue of rear baking 30 minutes.

Corrosive liquid HNO3:H20:HCI=1:2:3,50 ℃ of water-baths 1 minute

Be soaked in and dissolve photoresist in the acetone, alcohol immersion dissolving acetone, deionized water rinsing, nitrogen dries up, and places baking oven dry, prepares the deposition of IGCZO film.

2) growth IGCZO lamination layer structure

Adopt physical evaporation low temperature depositing (PELD) the evaporation oxidation thing ZnO of system, Ga2O3, In2O3 and Ca2O3, successive sedimentation growth IGCZO and C-IGCZO composite bed film on the ito glass substrate.Evaporate that used target InGaZn1-xCaxO is mixed according to certain ratio by 99.99% ZnO, Ga2O3, In2O3 and Ca2O3 powder, compacting, calcination form, wherein grow channel layer #1 target x value by 0.001 to 0.005, and growth of cubic phase insulating barrier #2 target x value is 0.01.Electron Beam Focusing is in the #1 of working region target, and underlayer temperature remains on 250 ℃ during evaporation, and settling chamber's operating air pressure is 5.0 * 10-2Pa, evaporation speed 5-10nm/ minute, deposit thickness 50-100nm.Deposit 400 ℃ of annealing of complete original position 30 minutes.Rotation #2 target is to the working region, and settling chamber's operating air pressure is 5.0 * 10-2Pa, evaporation speed 5-10nm/ minute, deposit thickness 150-200nm.After taking out, the IGCZO composite bed of growth under 400 ℃ of oxygen atmospheres, annealed 30 minutes, to eliminate the defective in the film.

2.IGCZO composite bed TFT device later stage preparation flow is as follows:

L) etching Al

Deposited by electron beam evaporation 300nm Al electrode, conventional photoetching, 60 ℃ of water-bath H3PO4:5%H2O2 corrode Al and IGCZO, it should be noted that here if etchant solution does not have H2O2, have following chemical reaction to occur:

Al+H3P04→H2+AlPO4

Zn+H3P04→H2+Zn3(PO4)2

H2 can corrode IT0, reacts as follows

SnO2+H2→Sn?or?SnOx，x<l

Sn+H3PO4 → H2+Sn3 (PO4) 4, Sn3 (PO4) 4 is solvable

Corroding rapidly the IGCZO composite bed, H3PO4 solution destroys electrograph shape at utmost point short time internal corrosion ITO.So allocate 10% H2O2 here in solution, purpose is to suppress the corrosion of ITO electrode material,

Its chemical reaction is as follows:

Al+H3PO4→H2+AlPO4

AlPO4 is as catalyst, H2O2 → H2O+O2

Thereby O2 can take away rapidly the corrosion that H2 suppresses ITO in the solution in the solution.

2) wet etching IGCZO

Wet etching IGCZO adopts 60 ℃ of corrosion of solution water-bath of H3PO4:H2O proportioning, and the H3PO4 etchant solution of why selecting to release is to consider that the IGCZO active layer thickness here only has 70nm-100nm, and is short with the H3PO4 reaction time of dilution, is not easy control.

The transparent film transistor of the present invention take the IGCZO material as primary structure, device feature size W/L=90/30 micron, thickness of insulating layer 200nm, output current is near 10 μ A, the current switch characteristic〉104, effective mobility μ EF=0.6cm2/Vs, mutual conductance peak value gm=9.8 μ s/mm.

IGCZO is applicable to the electronic device of visible transparent as transparent material.Take H-IGCZO or Mixed-IGCZO wide bandgap semiconductor as raceway groove, good hafnium C-IGCZO is that insulating barrier prepares active layer/insulation layer structure, can be applied to TFT.Adopt physical evaporation preparation technology in low temperature (PELD) low-temperature epitaxy InGaZn1-xCaxO crystal film on the ito glass substrate, film surface is smooth, and visible light transmissivity is high.Ultraviolet-near-infrared transmission spectrum and XRD analysis show, along with the increase of Ba component in the film, the InGaZn1-xCaxO film changes the Emission in Cubic structure into by six side's phase structures.PELD growth InGaZn1-xCaxO alloy firm, thus the carrier concentration that x regulates alloy regulated by different target proportionings.

In TFT flow technique, note in active layer IGCZO growth course, reduce fault in material, optimize the channel conduction performance, the size growth of control gate insulating barrier IGCZO.Thereby obtain the TFT device of low driving voltage, high on-off ratio.

Claims (4)

1. an IGCZO TFT growth technique is characterized in that

This IGCZO growth technique comprises:

The corrosion ito glass;

Growth IGCZO lamination layer structure

Wherein, IGCZO composite bed TFT device later stage preparation flow is as follows:

Etching Al;

Wet etching IGCZO.

2. IGCZO TFT growth technique as claimed in claim 1 is characterized in that, above-mentioned corrosion ito glass comprises and use corrosive liquid HNO3:H20:HCI=1:2:3,50 ℃ of water-baths 1 minute.

3. IGCZO TFT growth technique as claimed in claim 1 is characterized in that,

Above-mentioned growth IGCZO lamination layer structure comprises employing physical evaporation low temperature depositing (PELD) the evaporation oxidation thing ZnO of system and BaO, successive sedimentation growth IGCZO and C-IGCZO composite bed film on the ito glass substrate.

4. IGCZO TFT growth technique as claimed in claim 1 is characterized in that,

Above-mentioned wet etching IGCZO comprises the 60 ℃ of wet etching IGCZO of solution water-bath that adopt the H3PO4:H2O proportioning.