PN junction and the SE one step completed method of diffusion that adulterates
Technical field
The invention belongs to technical field of semiconductors, be specifically related to a kind of PN junction and the SE one step completed method of diffusion that adulterates.
Background technology
To semiconductor inside such as Si and GaAs, mixing alms giver or acceptor impurity atomic time, because the radius of alms giver or acceptor impurity atom is generally all larger, it is very difficult wanting them directly to enter into that semiconductor lattice goes, the technology the most often adopting is thermal diffusion, high temperature can make lattice produce some thermal defects, these impurity of help by these thermal defects spread relatively easily and enter into semiconductor and go, and for thermal diffusion technology, often all need higher diffusion temperature.
Tubular type diffusion is one of the most frequently used major way of thermal diffusion.Tubular type diffusion is a batch diffusion, with intermittent mode operation, need to be diffused thing by hundreds of at every turn and vertically be placed on support by artificial or special instrument, advance in diffusion furnace and pass into high pure nitrogen and phosphorus oxychloride is carried out high-temperature process, then cooling rear taking-up, circulation repeatable operation.The advantage of tubular type diffusion is closed-loop operation, and diffusional environment cleanliness factor is high, and battery conversion efficiency is high; Its shortcoming is can not continuous operations, and production capacity is low, diffusion cost is high.Simultaneously because dopant spreads in gaseous state mode in advance built in parts surface, the thermal field of square resistance and diffusion furnace distribution after diffusion, to be diffused in the position of thing in stove, body of heater intake method, stove air-flow distribution etc. relevant, cause PN junction square resistance to be uniformly distributed and to there are differences at same parts surface, conventionally each parts surrounding square resistance is lower than middle square resistance, and inhomogeneities is more than 5%.In addition, the dopant source of tubular type diffusion is generally liquid phosphorus oxychloride, is dangerous goods, need to strictly manage on the one hand, requires on the other hand diffusion furnace to seal, once otherwise careless mistake in use occurs, may cause life to injure safely.
Patent EP1010960A1 relates to one for the preparation of the horizontal chain diffusion furnace of solar cell, mode of heating is infrared heating, wherein with certain density phosphoric acid solution, to substitute dangerous liquid phosphorus oxychloride evenly to spray on silicon chip, again silicon chip high-temperature process in chain type diffusion furnace is generated to PN junction, it indicates silicon chip and can adopt metal mesh belt to transmit, metal furnace zone in use easily makes to be diffused the pollution that thing is subject to metal impurities, also because serialization equipment furnace inner environment atmosphere cleanliness factor is not easy the reasons such as assurance, the low 0.1-0.2% of efficiency of the solar cell that efficiency of solar cell prepared by this chain type diffusion furnace is prepared than tubular type diffusion way, in transmitting procedure, the easy sideslip of silicon chip, fragment rate is higher, when conveyer belt leaves body of heater, also heat can be taken away, equipment power consumption is high.This patent has also been introduced a kind of method that replaces nichrome metal mesh belt transmission cell piece with high-purity ceramic roller-way, roll shaft at least a portion of its description is comprised of a series of transparent roll shaft continuous arrangements, roll shaft can autorotation with driving, and synchronously rotate by parts direct of travel, parts can move to another roll shaft from a roll shaft by the frictional force of roll shaft.But this patent does not relate to the problem that how to keep the cleanliness factor of furnace inner environment atmosphere to guarantee diffusion effect, and this equipment does not have SE function.
Patent CN1602554A has set forth a kind of baking oven, for the electrooptical device of being made by semi-conducting material, be characterized in that roller that the transmission of semi-conducting material is made by series of ceramic material is realized and roller rotates around the axis of himself, as a continuous production device that semi-conducting material is heat-treated, this patent does not relate to the problem that how to keep the cleanliness factor of furnace inner environment atmosphere to guarantee result of use equally, and this equipment does not have SE function yet.
Selective emitter (selective emitter is called for short SE) is exactly under emitter electrode, on silicon face, to make a high-dopant concentration region, and metal electrode is produced on area with high mercury, and other regions are low concentration region.With the silicon solar cell of this structure fabrication, select exactly emitter region battery, high-doped zone declines metal and semi-conductive contact resistance, thereby raising fill factor, curve factor, the short circuit current of battery is improved in doped regions, thereby can improve the conversion efficiency of battery, higher more than 1% than the transformation efficiency without SE battery.The world-class PERL battery of University of New South Wales's conversion efficiency is exactly a kind of SE battery, what it adopted is laboratory process, after adopting photoetching technique to prepare SE window on the silicon chip of thermal oxidation, adopt thermal diffusion to form high-doped zone, after oxide layer is fallen in pickling again, another warm diffuses to form doped regions, the oxidation several times of SE battery, photoetching and a diffusion process, be difficult in large-scale industrial production promote.
Also have a kind of SE preparation technology that high concentration phosphorus slurry is printed onto to silicon chip surface as electrode grid wire, then silicon chip is put into conventional diffusion furnace and spread.High concentration phosphorus slurry deposits to non-Printing Zone from Printing Zone volatilization in diffusion process, but the phosphorus concentration that volatilization deposition like this obtains is too low, be difficult to reach the diffusion requirement of SE and low concentration region, need to be when diffusion, pass into nitrogen and phosphorus oxychloride gas supplementing as phosphorus source, because used phosphorus oxychloride, so can only complete in airtight tubular diffusion furnace.The technology of preparing of this SE need to increase by one phosphorus slurry printing process and can not realize serialization and produce before routine diffusion.
As known from the above, prior art exists the low and serialization diffusion facilities of PN junction and SE doping can not once complete, serialization diffusion facilities is produced production interchange efficiency to be difficult to guarantee the problems such as cleanliness factor of diffusional environment atmosphere.
Summary of the invention
The object of this invention is to provide a kind of PN junction and the SE one step completed method of diffusion that adulterates.The method not only effectively solves PN junction and the SE one step completed problem of adulterating, and realizes the serialization of PN junction and SE doping process and produces, but also solve the cleanliness factor problem of diffusional environment atmosphere in serialization production process.
PN junction of the present invention and the SE one step completed method of diffusion that adulterates, the method is on the diffusingsurface of thing, to form the coating that one deck contains dopant being diffused, the coating forming in PN junction region and SE region has respectively different density or concentration or component; Wherein, SE zone-coating density or concentration are higher than PN junction zone-coating density or concentration; Or the component of its dopant of coating in SE region and PN junction region is different; By surface attachment the thing that is diffused of above-mentioned coating at high temperature process, once complete the doping of PN junction and SE.
Preferably, by silk screen printing or laser spraying technique, in SE region and PN junction region, once prepare density or the different coating that contains dopant of concentration, then it is at high temperature processed, once complete the doping of PN junction and SE.Wherein, the half tone that is used for carrying out silk screen printing has different printing characteristics for SE region and PN junction region, be that the coating density of SE region printing or coating density or the concentration of the printing of concentration ratio PN junction region are high, realize one-step print and in SE region and PN junction region, form respectively the coating of different densities or concentration.
Preferably, be used for carrying out the half tone of silk screen printing, SE region is comprised of the pierced pattern interpenetrating, PN junction region is comprised of some disconnected patterns, and this disconnected pattern comprises circle (point-like) or linear or square or triangle or rhombus or other any disconnected figures.Or, the half tone that is used for carrying out silk screen printing, SE region etching degree is higher than PN junction region etching degree.
Preferably, be first diffused the SE figure that on thing diffusingsurface, preparation contains dopant, then on same diffusingsurface, forming the coating that contains dopant that density or concentration or component are different, finally carrying out together high-temperature process, completing the doping of PN junction and SE.Wherein, the SE figure that it contains dopant can adopt silk screen printing or laser spraying mode to prepare, and its coating that contains dopant can adopt atomizing spraying or laser spraying or silk screen printing or spin coating mode to prepare.
Preferably, surface attachment described coating be diffused thing, remain diffusingsurface upward, one group can along under the transmission of the horizontal roller of axis direction reciprocating rotation successively continuously by high temperature treating device, uninterrupted, the disposable doping that completes PN junction and SE; Or, surface attachment described coating be diffused thing, also can under plumbness, carry out by conventional tubular diffusion furnace high-temperature process, intermittent, the disposable doping that completes PN junction and SE.
Preferably, be prepared with the thing that is diffused of described SE figure, remain that diffusingsurface upward, one group can along under the transmission of the horizontal roller of axis direction reciprocating rotation successively continuously by preparation facilities and the high temperature treating device of described coating, uninterrupted, the disposable doping that completes PN junction and SE.If desired, prepare after described SE figure being diffused on thing diffusingsurface, first by drying and processing, then on thing diffusingsurface, form described coating being diffused.
Preferably, be prepared with the thing that is diffused of described SE figure, under the transmission of horizontal roller, successively in continuous moving process, by being arranged on atomizing spraying or the laser spraying device of horizontal roller top, complete the preparation of described coating.
Preferably, roller-way at least a portion that transmission is diffused thing is comprised of hollow axle roller, the position that is diffused thing process on hollow axle roller is radially provided with some air vent holes, at least one end at hollow axle roller is connected with air inlet pipe by swivel joint, from air inlet pipe, can pass into clean nitrogen, compressed air or other necessary gas, this gas enters into the burner hearth position that is diffused thing process by the air vent hole on hollow axle roller, owing to there being all the time the gas of fresh cleaning to spray from the air vent hole of hollow axle roller, and be diffused thing, from the air vent hole top of hollow axle roller, pass through always, thereby the clean gas of constantly ejection will be diffused thing encirclement, stop external gas to approach and be diffused thing, thereby formed local very clean subenvironment around being diffused thing, therefore, can be not tight because of diffusion furnace furnace sealing, exogenous impurity gas enters burner hearth and affects the cleanliness factor of heat treatment operational environment, therefore, can play a protective role to diffusional environment.Wherein, the some air vent holes that radially arrange on hollow axle roller, can be aperture of the same race and different pore size, can be proportional spacing or inhomogeneous spacing, to reach being uniformly distributed of gas.For not to being diffused thing or diffusion technology pollutes, the material of hollow axle roller can be quartz glass tube, quartz-ceramics pipe, alumina ceramic tube, silicon nitride ceramics pipe etc., and first-selection is quartz glass tube and quartz-ceramics pipe.
Preferably, on hollow axle roller, be diffused the position that is provided with some air vent holes of thing process, be provided with at least one middle concave, the protruding step in both sides, be diffused thing moves horizontally under the support of both sides raised step and frictional force effect, be diffused between thing and air vent hole and leave certain distance, gas enters burner hearth without barrier below being diffused thing.
Preferably, being diffused thing can be that silicon chip, germanium wafer, gallium arsenide film or other can carry out the material of PN junction doping; Dopant can be phosphorous or the compound of boron or aluminium or carbon or zinc or iron etc. or other can form the material of PN junction.
High temperature of the present invention, temperature, generally at 700-1000 ℃, is those skilled in the art's common practise.
The present invention has following beneficial effect:
PN junction provided by the invention and the SE one step completed method of diffusion that adulterates, not only can effectively solve PN junction and the SE one step completed problem of adulterating, and the serialization that can realize PN junction and SE doping process produces, can also solve the cleanliness factor problem of diffusional environment atmosphere in serialization production process.Because introduced SE technique in routine diffusion, can increase substantially diffusion effect, take crystal silicon battery as example, single crystal battery efficiency can improve 0.8%, polycrystalline battery efficiency can improve 0.4%; Because realized the serialization of diffusion technology under clean atmosphere, produce, not only can greatly improve output, reduce production costs, and guarantee stability and the reliability of diffusion technology.The present invention to optimizing solar cell technological process, improve battery efficiency, reducing production costs all has great importance.
Accompanying drawing explanation
Fig. 1 is PN junction and SE doping coating schematic diagram;
Fig. 2 is plater structural representation;
Fig. 3 is the structural representation of ventilation hollow axle roller;
Fig. 4 is ventilation step hollow axle roller structural representation;
1, SE region; 2, PN junction region; 3, disconnected pattern; 4, coated areas; 5, plater; 6, be diffused thing; 7, roll shaft; 701, spindle nose; 702, hollow axle roller; 703, air vent hole; 704, ventilation spindle nose; 705, swivel joint; 706, air inlet pipe; 707, step.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in further detail.
Embodiment 1
As Fig. 1 and Fig. 2, the present embodiment is SE region and the one step completed diffusion technology in PN junction region for silicon solar cell.Wherein being diffused thing is P type monocrystalline or polysilicon chip, adopts a kind of special screen painting phosphorus slurry, and this half tone has the figure shown in Fig. 1.Wherein 1 solid line is partly SE region, this district's figure is straight line, comprise thick lines millimeter more than magnitude and perpendicular to broad-brush several microns of hachure and frames to tens of micron dimensions, thick line can be designed as continuously, part is interrupted (connecting in centre), hollow out etc., number is two bars at the most, and hachure is partly necessary for continuously, and number is tens of to hundreds of bars, frame can be for continuous or snakelike, and width is consistent with hachure; The 2nd, PN junction region, blank or some disconnected patterns 3, consist of, this disconnected pattern 3, comprises circle (point-like) or linear or square or triangle or rhombus or other any disconnected figures, pattern dimension is in micron dimension, and spacing is zero to several microns; When printing, SE region 1 can see through phosphorus slurry completely, and PN junction region 2 can only partly see through phosphorus slurry, so just in the SE region 1 of silicon chip surface, has formed respectively the different phosphorus slurry of density with PN junction region 2.Or, adopt the mode of laser spraying in SE region, to starch with the PN junction region different phosphorus of spraying density respectively.Then this silicon chip with variant phosphorus slurry coating is heat-treated under the high temperature of 700-1000 ℃, the square resistance of silicon chip after heat treatment in SE region reaches 20 Ω cm, at PN junction region square resistance, be 40-200 Ω cm, once complete the doping of PN junction and SE.
Embodiment 2
As shown in Figure 1, Figure 2 and Fig. 3, the present embodiment is SE and the one step completed diffusion technology of PN junction for silicon solar cell.Wherein being diffused thing is P type monocrystalline or polysilicon chip, and silicon chip is through secondary coating process, and half tone figure as described in Example 1.First coating is at silicon chip surface printing SE figure by screen printing mode, the slurry adopting is phosphorus slurry, then silicon chip reaches below next spray equipment through the transmission of roll shaft, spray equipment is sprayed on silicon chip front surface by a certain proportion of phosphoric acid, namely cover LiaoSEHe PN district, then its level under the transmission of roller-way is entered and in high-temperature furnace body, carries out high-temperature process.Because there has been phosphorus slurry in SE region below phosphoric acid, the square resistance in final SE region reaches 20 Ω cm, PN junction region square resistance is 40-200 Ω cm, once completes the doping of PN junction and SE.
Embodiment 3
As shown in Figure 1, Figure 2 and Fig. 3, the present embodiment is SE and the one step completed diffusion technology of PN junction for silicon solar cell.Wherein being diffused thing is P type monocrystalline or polysilicon chip, and silicon chip is through secondary coating process, and half tone figure as described in Example 1.First coating is at silicon chip surface spraying SE figure by laser spraying device, the slurry adopting is phosphorus slurry, after 200 ℃ of oven dry, this silicon chip reaches below next spray equipment through the transmission of roll shaft, spray equipment is sprayed on silicon chip front surface by a certain proportion of phosphoric acid, namely covered SE and PN region, then its level under the transmission of roller-way has been entered in drying oven and high temperature furnace and spread.Because there has been phosphorus slurry in SE region below phosphoric acid, the square resistance in final SE region reaches 20 Ω cm, PN junction region square resistance is 40-200 Ω cm, once completes the doping of PN junction and SE.
Embodiment 4
As shown in Figure 1, Figure 2 and Fig. 3, the present embodiment is SE and the one step completed diffusion technology of PN junction for silicon solar cell, comprises coating procedure, heat treatment process and a laser treatment process.Wherein being diffused thing is P type monocrystalline or polysilicon chip, first through roll shaft, transmission is placed in spray equipment below to the silicon chip of processing through making herbs into wool, spray equipment is sprayed on whole silicon chip surface by special phosphorus slurry, after the high-temperature heat treatment of 200 ℃ of oven dry and 700-1000 ℃, silicon chip has formed PN junction, and square resistance is 40-200 Ω cm; Then through roll shaft, transmission is placed under a laser equipment silicon chip again, it is the software in SE region that laser equipment has been set up scanning pattern, to there being the silicon chip of PN junction to carry out forming SE region after laser scanning heating according to SE figure, the square resistance in SE region reaches 20 Ω cm, and continuity completes the doping of PN junction and SE.
Embodiment 5
As Fig. 3, the present embodiment is a kind of ventilation hollow axle roller, for substituting the steel band of existing chain type diffusion furnace and the solid roll of roll-type diffusion furnace transmission silicon chip, the structure of hollow axle roller as shown in Figure 3, the 702nd, a kind of hollow roll, the 701st, spindle nose, for fixation hollow roll shaft, the 703rd, the air vent hole of hollow shaft, pore can be aperture of the same race and different pore size, can be proportional spacing or inhomogeneous spacing, to reach being uniformly distributed of gas, the 705th, swivel joint, one end and spindle nose 704 join, the other end and air inlet pipe 706 are joined, from air inlet pipe, can pass into clean nitrogen, compressed air or other necessary gas, this gas enters into the burner hearth position that is diffused thing process by the air vent hole on hollow axle roller,
Or, as shown in Figure 4, on hollow axle roller 702, be diffused the position that is provided with some air vent holes 703 of thing 6 processes, be provided with at least one middle concave, the protruding step 707 in both sides, be diffused thing moves horizontally under the support of both sides raised step 707 and frictional force effect, be diffused between thing 6 and air vent hole 703 and leave certain distance, gas enters burner hearth without barrier below being diffused thing 6.Like this, the clean gas that enters burner hearth by air vent hole plays a protective role to diffusional environment, prevents that silicon chip from receiving pollution.
The efficiency of solar cell prepared by the efficiency of solar cell of preparing with the horizontal proliferation stove that this ventilation hollow axle roller is made and tubular type diffusion way maintains an equal level, solved and adopted the chain type diffusion battery of existing stainless steel guipure transmission silicon chip than the problem of the low 0.1-0.2% of tubular type diffusion battery efficiency, made diffusion technology serialization production under the prerequisite that does not reduce conversion efficiency of solar cell become possibility.In addition, operating silicon chip does not almost have perturbation action to each warm area thermal field, can within the extremely short time, settle out, therefore after adjusting process parameter, the continuous diffusion furnace of this roller bed type is not only applicable to industrial production, and the experiment and the teaching that are also applicable to frequent adjusting process parameter are used.
Although embodiment of the present invention are open as above, but it is not restricted to listed utilization in specification and execution mode, it can be applied to various applicable the field of the invention completely, for those skilled in the art, can easily realize other modification, therefore do not deviating under the universal that claim and equivalency range limit, the present invention is not limited to specific details and illustrates here and the legend of describing.