CN1800440A

CN1800440A - Preparation method of polycrystalline vanadium dioxide film with room temperature resistance temperature coefficient higher than 10%K

Info

Publication number: CN1800440A
Application number: CN 200510039179
Authority: CN
Inventors: 李金华; 袁宁一
Original assignee: Jiangsu Polytechnic University
Current assignee: Liyang Chang Technology Transfer Center Co., Ltd.
Priority date: 2005-04-30
Filing date: 2005-04-30
Publication date: 2006-07-12
Anticipated expiration: 2025-04-30
Also published as: CN100500928C

Abstract

The invention relates to a functional thin film material preparing technology, which adopts improved ion beam amplify deposited method to make the film and combines the subsequent crystallization and annealing to achieve the impurity element even immersing and the effective place-replacing to vanadium so that the phase starting temperature of the thin film reduces to 12-16 deg. It adjusts the argon /hydrogen ratio film craft and crystallizing heat treatment condition so that when the polycrystalline VO2 thin film transfers to the mental phase from the semiconductor phase, the change of the resistance ratio over 2 magnitude orders.

Description

Room temperature resistance temperature coefficient is higher than the preparation method of polycrystalline vanadium dioxide film of 10%/K

Technical field

The present invention relates to the film material with function technology of preparing, refer in particular to the preparation method of polycrystalline vanadium dioxide film that a kind of room temperature resistance temperature coefficient (TCR) is higher than 10%/K.

Background technology

Vanadium oxide film is the important sensitive membrane of a kind of preparation non-refrigeration focal surface infra-red imaging array (UFPA) and infrared eye.Its preparation method mainly contains sol-gel method that magnetron sputtering deposition, ion beam sputtering, pulsed laser deposition, Chinese patent 03115643.6 " preparation method of vanadium oxide thin film material " that Chinese patent 200410060770.1 " preparation method of the vanadium oxide film that transformation temperature is adjustable " mentions mention etc.Though the whole bag of tricks can both prepare vanadium oxide film, the performance of gained film, cost, and producibility have nothing in common with each other.At present, practical preparation method makes target with vanadium metal, the method for sputtering sedimentation VOx in oxygen atmosphere (x～2) film, and the heat resistance temperature coefficient (TCR) of practical VOx film is 2%～3% at present.Reached 5.2%/K with the mix TCR of vanadium dioxide film of preparation of sol-gel method tungsten.Because the size of TCR directly affects the height of UFPA detectivity, hope can improve near the TCR of vanadium oxide film room temperature as far as possible in the application.

In order to satisfy infrared eye, the actual process demand of UFPA development particularly mainly contains the requirement of four aspects: a high TCR that tries one's best to the vanadium oxide sensitive membrane; B densification, even; The interface of c and substrate adheres to; D and CMOS process compatible.Because the film with the sol-gel method preparation can not satisfy back three requirements, promptly enable to obtain higher TCR and also can only study as mechanism, and can not actual use in the device preparation.With the film of other method preparation, the very high TCR of difficult acquisition though can be used as the sensitive membrane of infrared acquisition and image device, has influenced the detectivity of device.

Summary of the invention

The present invention is for overcoming above-mentioned deficiency, a kind of preparation method of ultra high temp coefficient polycrystalline vanadium dioxide film is provided, ion beam enhanced depositing (the IBED-Ion Beam Enhanced Deposition) method that employing has improved, physical action is combined with chemical action, the phase transformation of vanadium dioxide polycrystal film is extended to low temperature, on silicon oxide and silicon nitride substrate preparation evenly, fine and close, with substrate adhere to good, TCR is higher than the polycrystalline vanadium dioxide sensitive membrane of 10%/K during with CMOS process compatible, 300K.

Realize that technical scheme of the present invention is:

(1) sputtering target is made in doping

Mo, Ta, W, Nb, the Mn oxide compound of 1-15% atomic ratio are evenly mixed V ₂O ₅Powder is with waiting static pressure to be pressed into sputtering target.

(2) adopt ion beam mixing to strengthen deposition

Select above-mentioned sputtering target for use, select Ar for use: H ₂The ion beam mixing that is high-purity gas generation in 1: 3～1: 9 bombards deposited film, beam intensity 8～10mA, argon/hydrogen combined beam beam diameter that the bombarding ion source produces is greater than 150mm, heterogeneity is less than 15%, vertically be injected on the sputtering sedimentation film, utilize the revolution and the sample strip rotation of sample table to realize evenly injecting, like this, the damaging effect that the high dosage argon ion injects makes V ₂O ₅Part of V-O bond rupture; The reduction effect of injecting hydrogen is with V ₂O ₅Price reduction converts VO to ₂Structure; The melange effect of bombarding beam makes that film combines with substrate interface firmly, membrane structure is fine and close.Bring into play physical action and chemical action simultaneously, form the IBED film.

(3) heat of crystallization is handled

With the ion beam enhanced depositing vanadium oxide film of method for preparing, through 500-700 ℃, argon gas that 10-30 divides or n 2 annealing, crystallization, the polycrystalline VO that obtained performance is good ₂Film.

Wherein, different critical Tcs is arranged to the IBED film of different filming conditions.To Ar/H ₂Than being 1: 3～1: 9, sputter line 100mA bombards the IBED film that mixes line 10mA, critical Tc is at 500～650 ℃, the heat of crystallization treatment temp is higher than 20～40 ℃ of critical Tcs, and crystallization time is selected 10～20 fens, determines according to subsequent device technology.

With the ion beam enhanced depositing method film forming of having improved,, realize near evenly mixing and, the phase transformation starting temperature of film being reduced to 12～16 ℃ of impurity to effective displacement of vanadium in conjunction with follow-up crystallization, annealing.Regulate argon/hydrogen ratio and wait film-forming process and heat of crystallization treatment condition, make polycrystalline VO ₂Film is when metallographic phase changes in opposite directions from semi-conductor, and the variation of its resistivity surpasses 2 orders of magnitude.Chosen doping element, adjusting dopant dose reach more than the 10%/K TCR of doped vanadium dioxide polycrystal film when 300K.

The invention has the advantages that:

(1) adopts the well behaved vanadium dioxide polycrystal film that phase-change characteristic is arranged of dried preparation, in conjunction with selecting preparation conditions such as preparation method, dopant dose, dopant species such as doping or introducing stress, the thin film phase change temperature is extended to low temperature suitably, guarantee that the stagnant Henan of phase transformation is enough little, the TCR that realizes near room temperature (300K) improves greatly, reach more than the 10%/K, can satisfy the service requirements of infrared acquisition and infrared imaging.

(2) adopt the ion beam enhanced depositing method improved, overcome the deficiency of the ion beam enhanced depositing method of existing simple physical method, utilize of the bombardment of big line ion beam mixing to deposit film, bring into play physical action and chemical action simultaneously, realize doping, price reduction, interface blended effect.Deposit film is combined with substrate interface firmly, also can make the compact structure of polycrystalline vanadium dioxide film, density reaches 4.23g/cm ³, very near the 4.34g/cm of monocrystalline vanadium dioxide ³The crystal boundary density of this film is low, and the oxygen room in the film is few.This also makes film improve in the intensity of activation of semi-conductor phase, thereby makes the more approaching TCR value with the monocrystalline vanadium dioxide than other vanadium oxide film of the temperature factor of film.After the doping, the displacement of impurity in the vanadium dioxide crystalline structure is more abundant, and the transformation temperature of film extends to low temperature, so can improve the TCR of film greatly., the present invention can make TCR be elevated to 10%/K with the multiple foreign atom of 5-12atm%,

(3) this film technique is without vanadium metal, and with cheap powder V ₂O ₅, embodied cost advantage.

(4) present technique is a kind of dry method deposition technique, does not have environmentally hazardous material discharging such as waste liquid, waste gas in film process.

Description of drawings

Fig. 1 is the ion beam enhanced depositing synoptic diagram

Among the figure 1, the plasma sputter source; 2, V2O5 target; 3, Ar+ ion sputtering bundle; 4, bombarding ion source; 5, Ar/H+ ion beam mixing; But 6 rotation deposited samples framves; 7, rotatable sample platform; 8, system vacuum bleeding point.

Fig. 2 is the annealing characteristic of ultra high temp coefficient IBED vanadium oxide film, among the figure a.500 ℃; B.530 ℃; C.550 ℃; D.600 ℃; E.630 ℃

Fig. 3 is the X-ray diffraction spectrum after the IBED vanadium oxide film argon annealed, among the figure a.600 ℃, 4 '; B.600 ℃, 12 '; C.650 ℃, 3 ';

Fig. 4 is the temperature-resistance change curve of ultra high temp coefficient vanadium dioxide polycrystal film, and the TCR of 300K is 10.2%/K among the figure

Fig. 5 is the XRD analysis result of the IBED film of different crystallization conditions, and a is 650 ℃ among the figure, 2min, and 600 ℃ of b, 5min, 550 ℃ of c, 19min, d is crystallization treatment not

Embodiment

The preparation process of the embodiment of the invention is as follows:

(1) the sputter preparation of shooting at the target

With purity high-purity V of 99.99% ₂O ₅Powder and purity are high-purity Sb of 99.99% ₂O ₃, Ta ₂O ₅, WO ₃, MoO ₃, MnO, Nb ₂O ₅Powder is with 100atm%:1-15atm%, uniform mixing, ball milling.For preventing to introduce impurity, ball milling adopts agate ball and agate jar, and rotational speed of ball-mill is controlled at per minute 40-60 to be changeed.With 100Kg/cm ²Pressure just molded, remake 2000Kg/cm ², 20 minutes etc. static pressure, obtain blocky sputtering target.At last, in box-type furnace, do air atmosphere thermal treatment, temperature rise rate in the time of 300 ℃～600 ℃ about 5 ℃/minute, 600 ℃ of insulations one hour, taking-up was stand-by behind the cooling cool to room temperature naturally.

(2) ion beam enhanced depositing

The sputter bundle is Ar+, beam intensity 80～100mA, acceleration voltage 1.5～2.5KV.The Kaufman ion source is fed Ar/H ₂Than the high-purity gas that is 1: 3～1: 9, the beam intensity of ion beam bombardment is 8～10mA, and acceleration voltage is 40～60KV.The diameter of no electric scanning bombarding beam is not less than 150mm, and heterogeneity is less than 15%.Sample and sample table are done independent rotation (rotating speed is respectively 3r/min and 24r/min), make to strengthen that sample temperature is lower than 300 ℃ in the deposition process.Strengthen the sedimentary time by the sedimentary film thickness decision of needs, the about 100nm/h of sedimentation rate.The synoptic diagram of ion beam enhanced depositing is seen Fig. 1.

(3) crystallization and anneal

Post-depositional film is made heat of crystallization and is handled in high pure nitrogen or argon atmospher, thermal treatment temp must be a little more than its critical Tc.Critical Tc is to strengthening sedimentary actual conditions, the particularly Ar/H dependency bigger than having, crystalline temperature height in argon gas than in nitrogen.To 1: 3-1: 9 Ar/H ratio, the critical Tc Tc of nitrogen atmosphere be at 500-650 ℃, the about 540-700 of the Tc of argon atmospher ℃.Can select suitable enhancing mode of deposition according to the requirement of development infrared device technology, and then obtain the critical Tc of needs.When the infra-red imaging array of development band CMOS sensing circuit, can select the nitrogen atmosphere recrystallization annealing temperature usually, crystallization condition is 530～550 ℃, 10～20 minutes (Fig. 2).Crystallization can detect with XRD, and suitable crystallization condition will obtain being positioned near unimodal (Fig. 3) 39.5 °, the crystal orientation of corresponding vanadium dioxide be M2 (002) to.The resistivity of IBED vanadium dioxide polycrystal film can be regulated with the heat treated temperature and time of crystallization.At 1-5 ohm. in the cm range, the TCR value of film is maximum.Barium oxide has very complicated valence state to be formed, and long annealing time all can cause VO after too high Tc or the formation vanadium dioxide structure ₂The price reduction of structure raises resistivity, and TCR reduces.Fig. 5 is under the different recrystallization annealing temperature conditions, the XRD analysis of IBED film spectrum.As can be seen, suitable annealing conditions is to forming the necessity of vanadium dioxide structure.The height of film resiativity will be determined according to the design of infrared components sensing circuit.

Claims

1. room temperature resistance temperature coefficient is higher than the preparation method of polycrystalline vanadium dioxide film of 10%/K, it is characterized in that:

(1) Mo, Ta, W, Nb, the Mn oxide compound with the 1-15% atomic ratio evenly mixes V ₂O ₅Powder is with waiting static pressure to be pressed into sputtering target;

(2) select above-mentioned sputtering target for use, it is done the sedimentary while of argon ion sputtering, use Ar: H ₂Than the ion beam mixing that is high-purity gas generation in 1: 3～1: 9 deposited film is bombarded, sputter bundle beam intensity 80～100mA, bombarding beam beam intensity 8～10mA forms the ion beam enhanced depositing vanadium oxide film; And the Ar that the bombarding ion source produces ⁺/ H ⁺Combined beam vertically injects sample, utilizes the revolution of sample table and sample strip rotation to realize evenly injecting;

(3) with the ion beam enhanced depositing vanadium oxide film of method for preparing, through 500～700 ℃, 10～30 minutes argon gas or n 2 annealing, crystallization, the polycrystalline VO that obtained performance is good ₂Film.

2. room temperature resistance temperature coefficient according to claim 1 is higher than the preparation method of polycrystalline vanadium dioxide film of 10%/K, it is characterized in that: to Ar/H ₂Than being 1: 3～1: 9, sputter line 100mA bombards the IBED film that mixes line 10mA preparation, critical Tc is at 500～650 ℃, the heat of crystallization treatment temp is higher than 20～40 ℃ of critical Tcs, and crystallization time is selected 10～30 fens, and film resiativity is adjusted in 1～5 ohmcm.

3. room temperature resistance temperature coefficient according to claim 1 is higher than the preparation method of polycrystalline vanadium dioxide film of 10%/K, it is characterized in that: the Kaufman ion source is fed Ar/H ₂Than the high-purity gas that is 1: 3～1: 9, the beam intensity of ion beam bombardment is 8～10mA, and acceleration voltage is 40～60KV.