Background technology
Silicon dioxide film has the dielectric properties that hardness is high, wear resistance good, heat insulating ability is good, light transmission rate is high, corrosion resistance is strong and good, is widely used, such as electronics integrated device, thin-film material, optical communication device etc. at numerous areas.In optical communication device, it is mainly used in planar optical waveguide material.
Planar Lightwave Circuit Technology is the novel integrated optics technique of one that last decade rises, there is simplicity of design, with existing ic process compatibility, integrated level is high, the features such as output is large, be widely used in Passive Optical Components, as array waveguide grating, optical branching device, star-type coupler etc.Also multiple for realizing the material of planar optical waveguide, as silicon-dioxide, InGaAsP, silicon oxynitride and polymkeric substance etc., but silicon-dioxide has many advantages compared with other material, as low in transmission loss, be easy to preparation, stable performance etc., and it has identical specific refractory power with optical fiber, be easy to and fibre-optic package, it is the good selection of planar optical waveguide material.
In quartz substrate, preparing silicon dioxide film is the core technology in planar optical waveguide, has directly determined the quality of optical signal transmission quality.Most base material all adopts silicon, and its shortcoming mainly contains 2 points: the first, because silicon and the brilliant key of the silicon dioxide film of growing afterwards have larger mismatch, easily produce larger stress and defect; The second, because silicon is different with the thermal expansivity of the silicon dioxide film of growing afterwards, in the time of annealing, easily cause the be full of cracks of film.And the composition of quartz substrate and the composition of silicon dioxide film are very approaching, so use quartz substrate just can avoid above problem.At present mainly contain chemical Vapor deposition process, thermal oxidation method, sputtering method and sol-gel method etc. for the method for silicon-dioxide film preparation; Wherein chemical Vapor deposition process quality of forming film is finer and close, and film forming is thinner, and stress is larger, need to repeatedly anneal; Thermal oxidation method speed is excessively slow, and can not in quartz substrate, prepare; Sputtering method poor controllability, and quality of forming film is bad; Sol-gel method complex operation, specific refractory power variable range is less, easily be full of cracks.
And compared with above several method, flame hydrolysis quality of forming film is good, sedimentation rate is fast, and step coverage is good, and stress is little, and cost is low, stable performance.Therefore,, with the flame hydrolysis silicon dioxide film of growing, particularly thick film growth is very necessary.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of method of preparing silicon dioxide film on quartz substrate surface, present method has overcome traditional preparation method's defect, realize the adjustable of silicon dioxide film specific refractory power, avoid separating out of silica crystals in annealing process, improved masking efficiency and quality.
For solving the problems of the technologies described above, the method that the present invention prepares silicon dioxide film on quartz substrate surface comprises the steps:
Step 1, quartz substrate is placed in to rotation and the Stage microscope of temperature control, utilizes the high temperature of oxyhydrogen flame 2500-3000 DEG C that hydrolysis reaction growth under-clad layer occurs on quartz substrate surface, the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas, air flow is respectively SiCl
48-15sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, under-clad layer growth thickness 15-20um;
After step 2, under-clad layer have been grown, sample is put into vacuum quick anneal oven, and 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keep 25-35 minute, rise to 1380-1430 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean under-clad layer surface, adopt chemical mechanical pulping to under-clad layer surface finish, roughness is dropped to below 5-10nm;
Step 3, sample is placed in to rotation and the Stage microscope of temperature control, utilizes the high-temperature hydrolysis of oxyhydrogen flame at under-clad layer surface growth sandwich layer, the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas and containing 10%(volume) GeCl
4ar/ GeCl
4mixed gas, air flow is respectively SiCl
48-15sccm, containing 10%(volume) GeCl
4ar/ GeCl
4mixed gas 8-25sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, sandwich layer growth thickness 4-6um;
After step 4, sandwich layer have been grown, sample is put into vacuum quick anneal oven, 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keep 25-35 minute, rise to 1380-1430 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean core layer surface;
Step 5, sample is placed in to rotation and the Stage microscope of temperature control, the high-temperature hydrolysis that utilizes oxyhydrogen flame is at the core layer surface top covering of growing, and the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas and containing 1%(volume) BCl
3ar/ BCl
3mixed gas, containing 1%(volume) POCl
3ar/ POCl
3mixed gas, air flow is respectively SiCl
48-15sccm, containing 1%(volume) BCl
3ar/ BCl
3mixed gas 5-10sccm, containing 1%(volume) POCl
3ar/ POCl
3mixed gas 0.8-1.5sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, top covering growth thickness 15-20um;
After step 6, top covering have been grown, sample is put into vacuum quick anneal oven, 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keeps 25-35 minute, rise to 1250-1350 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean top covering surface, obtain the silicon dioxide film on quartz substrate surface.
Method and the device of preparing silicon dioxide film due to the present invention on quartz substrate surface have adopted technique scheme, be placed in the Stage microscope of rotation and temperature control by quartz substrate, utilize the oxyhydrogen flame high-temperature hydrolysis under-clad layer of growing successively respectively on quartz substrate surface, sandwich layer and top covering, when each layer growth, hydrogen-oxygen rifle passes into gas with various, and control the air flow of each gas, Stage microscope temperature and the speed of growth, obtain the under-clad layer of different thickness, sandwich layer and top covering, after each layer growth, in vacuum quick anneal oven, carry out respectively anneal, and control intensification and cooling rate and sample soaking time in stove of annealing furnace, obtain the silicon dioxide film on quartz substrate surface.Present method has overcome traditional preparation method's defect, realizes the adjustable of silicon dioxide film specific refractory power, avoids separating out of silica crystals in annealing process, has improved masking efficiency and quality.
Embodiment
The method that the present invention prepares silicon dioxide film on quartz substrate surface comprises the steps:
Step 1, quartz substrate is placed in to rotation and the Stage microscope of temperature control, utilizes the high temperature of oxyhydrogen flame 2500-3000 DEG C that hydrolysis reaction growth under-clad layer occurs on quartz substrate surface, the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas, air flow is respectively SiCl
48-15sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, under-clad layer growth thickness 15-20um;
After step 2, under-clad layer have been grown, sample is put into vacuum quick anneal oven, and 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keep 25-35 minute, rise to 1380-1430 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean under-clad layer surface, adopt chemical mechanical pulping to under-clad layer surface finish, roughness is dropped to below 5-10nm;
Step 3, sample is placed in to rotation and the Stage microscope of temperature control, utilizes the high-temperature hydrolysis of oxyhydrogen flame at under-clad layer surface growth sandwich layer, the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas and containing 10%(volume) GeCl
4ar/ GeCl
4mixed gas, air flow is respectively SiCl
48-15sccm, containing 10%(volume) GeCl
4ar/ GeCl
4mixed gas 8-25sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, sandwich layer growth thickness 4-6um;
After step 4, sandwich layer have been grown, sample is put into vacuum quick anneal oven, 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keep 25-35 minute, rise to 1380-1430 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean core layer surface;
Step 5, sample is placed in to rotation and the Stage microscope of temperature control, the high-temperature hydrolysis that utilizes oxyhydrogen flame is at the core layer surface top covering of growing, and the removable hydrogen-oxygen rifle of hydrolysis reaction passes into respectively SiCl
4, H
2, O
2gas and containing 1%(volume) BCl
3ar/ BCl
3mixed gas, containing 1%(volume) POCl
3ar/ POCl
3mixed gas, air flow is respectively SiCl
48-15sccm, containing 1%(volume) BCl
3ar/ BCl
3mixed gas 5-10sccm, containing 1%(volume) POCl
3ar/ POCl
3mixed gas 0.8-1.5sccm, H
225-35sccm, O
212-20sccm, controls Stage microscope temperature 450-500 DEG C, speed of growth 5-6um/m, top covering growth thickness 15-20um;
After step 6, top covering have been grown, sample is put into vacuum quick anneal oven, 40-50 DEG C/s of annealing furnace heat-up rate, while rising to 900 DEG C, keeps 25-35 minute, rise to 1250-1350 DEG C with 40-50 DEG C/s more afterwards, keep 4-5 hour, then cool to 25 DEG C with 40-50 DEG C/s, take out sample, use successively acetone, ethanol, water to clean top covering surface, obtain the silicon dioxide film on quartz substrate surface.
In above-mentioned steps, the sccm of air flow unit represents standard state gas milliliter per minute (standard-state cubic centimeter per minute), and in the hydrolysis reaction of growth under-clad layer, sandwich layer, top covering, the temperature of oxyhydrogen flame is all set as 2500-3000 DEG C.
As shown in Figure 1, the silicon dioxide film preparing by present method is the under-clad layer 2, sandwich layer 3 and the top covering 4 that become at quartz substrate 1 surface growth row.
As shown in Figure 2, this silicon dioxide film can obtain by following preparation facilities, and this device comprises pressure source 5, H
2gas tank 11, O
2gas tank 12, SiCl
4gas tank 13, Ar/GeCl
4gas tank 14, Ar/BCl
3gas tank 15, Ar/POCl
3gas tank 16, flow control system 7, controlled valve Controlling System 8, movably hydrogen-oxygen rifle 9 and rotating temperature controlled Stage microscope 10, described pressure source 5 connects described H by some controlled valves 6 respectively
2gas tank 11, O
2gas tank 12, SiCl
4gas tank 13, Ar/GeCl
4gas tank 14, Ar/BCl
3gas tank 15 and Ar/POCl
3gas tank 16, described H
2gas tank 11, O
2gas tank 12, SiCl
4gas tank 13, Ar/GeCl
4gas tank 14, Ar/BCl
3gas tank 15 and Ar/POCl
3hydrogen-oxygen rifle 9 movably described in gas tank 16 connects respectively by described flow control system 7, described controlled valve Controlling System 8 is controlled respectively switching and the aperture of described some controlled valves 6, described rotating temperature controlled Stage microscope 10 be located at described in hydrogen-oxygen rifle 9 belows movably, quartz substrate 17 is placed on Stage microscope 10.Above-mentioned pressure source 5 can adopt pressure pump.
Present method is carried out based on flame hydrolysis, first in quartz substrate, carry out high-temperature hydrolysis and obtain comprising the loose porous silicon-dioxide thick film of one deck of under-clad layer, sandwich layer and top covering, then under vacuum condition, carry out short annealing and solidify backflow, thereby obtain transparent uniform silicon-dioxide thick film.In the time of hydrolysis reaction, pass into GeCl
4gas, the GeO of generation
2can make the doping silicon dioxide film specific refractory power of preparation improve 1.5%, can be used for making the material of waveguide.In the time of hydrolysis reaction, add BCl
3, POCl
3gas, the B of generation
2o
3and P
2o
5can, in the situation that ensureing doping silicon dioxide film specific refractory power and general silica film refractive index match, reduce solidification value, while preventing silicon-dioxide annealing, crystallization reaction, obtains high quality thick film.
Principle of the present invention is SiCl
4gas issues raw hydrolysis reaction in the condition of oxyhydrogen flame and generates amorphous carbon/silicon dioxide particle, and at high temperature annealing, makes silica dioxide granule melting and solidification, forms the silicon dioxide film of vitreous state.GeO
2specific refractory power higher than SiO
2therefore, pass into GeCl
4after gas reaction, can improve the specific refractory power of doping silicon dioxide film.B
2o
3can effectively prevent separating out of silica crystals in annealing process, reduce solidification value, and B
2o
3specific refractory power lower than SiO
2, P
2o
5specific refractory power higher than SiO
2.Therefore can be by the BCl mixing simultaneously
3, POCl
3gas can prevent that silica crystals from separating out, and reduces solidification value, ensures that doping silicon dioxide film specific refractory power and general silica specific refractory power are consistent simultaneously.
While utilizing said apparatus to prepare silicon dioxide film, pressure source is by controlled valve selective reaction gaseous species, and controlled valve opens and closes by the control of controlled valve Controlling System.Growth under-clad layer, when general silica, selects H
2, O
2, SiCl
4three kinds of gases; Growth sandwich layer, when germanium-doped silica, selects H
2, O
2, SiCl
4, GeCl
4four kinds of gases; Growth top covering, when the silicon-dioxide of separating out without crystal when solidification value reduces, anneals, except selecting H
2, O
2, SiCl
4outside three kinds of gases, also need to add BCl
3, POCl
3gas.After choosing reactant gases, participate in the controlled valve aperture of reactant gases by every kind of controlled valve Controlling System control, participate in the real-time traffic of reactant gases by every kind of flow control system control, and feed back in time controlled valve Controlling System, with set(ting)value contrast, carry out gas flow adjustment.After participating in the stability of flow of reactant gases, by H
2, O
2two-way gas is supplied to hydrogen-oxygen rifle one side, and remaining gas is supplied to hydrogen-oxygen rifle opposite side.After gas fully mixes, light the oxyhydrogen flame of hydrogen-oxygen rifle, will there is following hydrolysis reaction in the quartz substrate surface on Stage microscope under high temperature:
2?H
2(v)+?O
2(v)→2H
2O(v)
SiCl
4(v)+2H
2O(v)→SiO
2(s)+4HCl(v)
GeCl
4(v)+2H
2O(v)→GeO
2(s)+4HCl(v)
2BCl
3(v)+3H
2O(v)→B
2O
3(s)+6HCl(v)
2POCl
3(v)+3H
2O(v)→P
2O
5(s)+6HCl(v)
Wherein v represents gaseous state, and s represents solid-state.
Will be in quartz substrate Surface Creation particulate silica when hydrolysis reaction occurs, by regulating Stage microscope temperature, oxyhydrogen flame temperature controlling diaphragm to be grown to amorphous silicon di-oxide, by fast rotational Stage microscope, and carry out by mobile hydrogen-oxygen rifle the homogeneity that controlling diaphragm is grown.After hydrolysis reaction completes, will in quartz substrate, obtain the loose porous powdered form silicon dioxide film of one deck.Then product is put into vacuum quick anneal oven and be cured backflow.When annealing, adopt and heat up fast and cooling, to avoid crystal to separate out, cause the defect of silicon dioxide film.Annealing is carried out in a vacuum, to avoid introducing other impurity, can also improve and heat up and cooling rate simultaneously.In the time that annealing furnace temperature is raised to 850-950 ° of C, will stay for some time, as Procuring processing, to remove the pore of introducing in process of growth.Be rapidly heated again afterwards about 1400 ° of C, keep 3 to 5 hours.Last fast cooling is to room temperature.Adding BCl
3, POCl
3, generate B
2o
3, P
2o
5after, can make reflux temperature be reduced to 1300 ° below C, avoid crystal to separate out simultaneously, improve yield rate.