CN102544195A - Solar cell and manufacturing method thereof - Google Patents

Abstract

The invention discloses a manufacturing method of a solar cell. The manufacturing method comprises the following steps of: 1, accelerating P type ions and forming a P type local doping region on the back face of a P type wafer through ion injection; 2, forming an N type doping layer on the front face of the P type wafer; 3, forming coatings on the front face and the back face of the P type wafer, wherein each coating consists of a passivation layer and a reflection reducing coating; 4, forming a surface electrode on the front face of the P type wafer; 5, forming a back face electrode on the back face of the P type wafer, wherein the back face electrode is positioned at a position which corresponds to the P type local doping region; and 6, sintering the P type wafer at the temperature of 700-1,100 DEG C to compound a metal electrode element with a silicon eutectic crystal in the wafer, wherein when a P type is replaced by an N type, the N type is replaced by the P type simultaneously. The invention further discloses a solar cell. In the invention, a selective emitter and a local back field structure are adopted, so that contact resistance between the surface electrode and a substrate is reduced, and the photoelectric conversion efficiency of the solar cell is increased.

Description

Solar cell and preparation method thereof

Technical field

The present invention relates to a kind of solar cell and preparation method thereof, particularly relate to a kind of solar cell and preparation method thereof with selective emitting electrode structure.

Background technology

After solar cell received illumination, battery produced electron-hole pair after absorbing the incident photon of an energy greater than band gap width, and electronics and hole are energized into the upper state of conduction band and valence band respectively.Moment after exciting, the energy of incident photon is depended in electronics and hole in the energy position of excitation state.The photo-generated carrier that is in upper state very fast with the lattice interaction, energy is given phonon and is fallen back at the bottom of the conduction band and top of valence band, this process is also referred to as the thermalization process, the thermalization process make high-energy photon energy loss a part.After the thermalization process, the transport process of photo-generated carrier will have recombination losses in (barrier region or diffusion region).Last voltage output once pressure drop again, pressure drop derive from the difference with the work function of electrode material.By above-mentioned analysis, solar battery efficiency receives material, device architecture and preparation technology's influence, comprises the light loss of battery, limited mobility, recombination losses, series resistance and the bypass resistance loss etc. of material.For certain material, battery structure and preparation technology's improvement is important to improving photoelectric conversion efficiency.

In general solar cell preparation technology mainly passes through following process, is the example explanation with the silicon chip:

1, the surface treatment of silicon chip: prepare on the surface of silicon chip is the first step main technique of making silicon solar cell, and it comprises the chemical cleaning and the surface corrosion of silicon chip.After cutting into the silicon chip of accords with production requirement to the good silicon ingot that mixes on request; At first will be to its surface treatment; Because cutting back silicon chip surface has dust, organic substances such as metal ion and other inorganic matters and grease also can produce certain mechanical damage layer when cutting.Can get rid of these pollutions and damage through sour corrosion and alkaline corrosion, make the silicon chip surface light.Afterwards, silicon chip is put into sodium hydroxide solution or other acid solution of 1.2%-1.5% and done the pyramid matte, incident light is repeatedly reflected on the surface and reflect, increased the absorption of light, improved the efficient of battery.

2, diffusion system knot: making the knot process is on a block matrix material, to generate the different diffusion layer of conduction type, and preceding surface treatment all is the critical processes in the battery manufacture process with the system knot for it.Diffusion is a kind of phenomenon of material molecule or atomic motion.The method of thermal diffusion system P-N knot is to make V family impurity infiltrate P type silicon or the impurity infiltration N of III family type silicon through high temperature.The most frequently used V family impurity of silicon solar cell is phosphorus, and what III family impurity was the most frequently used is boron.Requirement to diffusion is junction depth and the diffusion layer square resistance that obtains to be suitable for solar cell P-N knot needs.The shallow junction dead layer is little, and battery shortwave effect is good, and shallow junction causes that series resistance increases, and has only the density that improves gate electrode, could effectively improve the fill factor, curve factor of battery.So just increased technology difficulty.Junction depth is too dark, and dead layer is apparent in view.If diffusion concentration is too big, then cause heavy doping effect, the open circuit voltage of battery and short circuit current are descended.In the battery of reality is made, considered the factor of many aspects, so the junction depth of solar cell generally is controlled at 0.3～0.5 micron, 20～70 ohm of square resistance average out to.At present, the used main thermal diffusion method of silicon solar cell is liquid source diffusion, and this technology is that the method for carrying through gas is with realizing in impurity band such as the diffusion furnace.

3, trimming: in diffusion process, also formed diffusion layer at the periphery surface of silicon chip, peripheral diffusion layer can make the upper/lower electrode of battery form short-circuited conducting sleeve, must it be removed.Existing any small partial short-circuit that the battery parallel resistance is descended on the periphery, is fatal to the influence of battery.The main method of trimming has etch, extrusion and ion dry etching etc.It is now industrial that the longest what use is plasma method, feed nitrogen, oxygen and carbon tetrafluoride high pressure and produce aura down, by oxonium ion and fluorine ion alternately to the silicon effect, remove the diffusion layer periphery lead with layer.Because generated P, P in the diffusion₂O₅, S_iO₂And phosphorosilicate glass, cleaned 2 minutes with 10% HF solution now, reach the purpose of decontamination glass.

4, make antireflective coating: illumination is mapped on the silicon chip on plane, and wherein some is reflected, even the silicon face of matte also has 11% reflection loss approximately, covers one deck antireflective coating at silicon face, can reduce reflection of light greatly.The spraying process that adopts now, it is to utilize high temperature to generate titanium dioxide film at silicon face; The method that also has a kind of spraying is with PECVD (plasma chemistry gaseous phase deposition) system, and it is by computer control, and under vacuum, high-voltage radio-frequency source condition, ammonia that makes and silane gas ionization form silicon nitride film at silicon face.

5, electrode is made: electrode is exactly the electric conducting material that forms tight ohmic contact with P-N knot two ends.Such material should satisfy: can form firm contact and contact resistance is little, excellent conductivity, little, the high requirement of collection efficiency of shielded area with silicon.A large amount of adopted technologies are silver slurry or silver-colored aluminium paste printing in the commercialization battery production at present; And this technology moves to maturity; The ratio of width to height of grid line reduces greatly; This and battery electrode designing principle---make the output of battery maximum, promptly as far as possible little and illumination active area battery of the series resistance of battery is as far as possible greatly on all four.

6, electrode is made and is finished the next operation-sintering of having arrived.Sintering is last one production process of solar energy monolithic battery, and good temperature curve is crucial in this step, and sintering time will be got hold of, and at first wants low temperature by the eliminating of the materials such as mixing agent in the slurries, heats or is sintered to aluminium-above sintered alloy of silicon eutectic point.Through after the alloying, along with cooling, the silicon in the liquid phase will solidify again; Formation contains the recrystallized layer of a certain amount of aluminium, and it is actually a process that silicon is mixed, and it has compensated the donor impurity in the N+ layer of the back side; Obtain with aluminium doped P-type layer, along with the rising of alloy temperature, the increasing proportion of the aluminium in the liquid phase; Under enough aluminium amount alloy temperatures, the back side even can form the electric field identical with the place ahead becomes back of the body electric field; This technology has been used in the large batch of commercial production at present, thereby has improved open circuit voltage and short circuit current, and has reduced the electrode contact resistance.Temperature and factors such as time and temperature that can back of the body knot burn with the doping content of the resistivity of stock, reverse diffusion layer and thickness, back side thickness or printing aluminum layer thickness, sintering all have relation.The two poles of the earth of battery are burnt in the too high meeting of temperature, badly damaged battery, and the not high enough ohmic contact formedness that can not guarantee electrode of temperature is so must there be a suitable temperature to remove sintering.The solar battery sheet of monolithic has just been accomplished like this, arrives test at last, is welding and packaging technology then.

Because the concentration of dopant ion can't be precisely controlled in the thermal diffusion process, causes the conversion efficiency of solar cell to be limited to, and can't carry out opto-electronic conversion efficiently.And adopting thermal diffusion process to prepare solar cell, its processing step is more, causes the reduction of production efficiency and the raising of cost.

Summary of the invention

The defective that the technical problem that the present invention will solve is that the prior art conversion efficiency of solar cell is low in order to overcome, the concentration of dopant ion can't be precisely controlled and processing step is complicated, cost is higher in the thermal diffusion process, what provide that a kind of processing procedure cost is low, dopant ion concentration is able to accurately control and photoelectric conversion efficiency is high has solar cell of selective emitting electrode structure and preparation method thereof.

The present invention solves above-mentioned technical problem through following technical proposals:

A kind of manufacture method of solar cell, its characteristics are that it may further comprise the steps:

Step S₁, quicken P type ion and form P type local doped region territory at P type chip back surface through the mode that ion injects, parameters such as the dopant ion that those skilled in the art can select to be fit to according to actual needs and the concentration of dopant ion, energy are to obtain suitable square resistance;

Step S₂, in P type wafer surface, form N type doped layer;

Step S₃, form coating at P type wafer surface and the back side, this coating is passivation layer and anti-reflection film;

Step S₄, form surface electrode in P type wafer surface;

Step S₅, form backplate at P type chip back surface, this backplate is positioned at and this corresponding position, P type local doped region territory;

Step S₆, with the sintering temperature of P type wafer at 700--1100 ℃, make the silicon eutectic in metal electrode element and the wafer compound, wherein preferably, with P type wafer 850--1000 ℃ sintering temperature 30 seconds to 30 minutes;

Wherein, when described P type replaced with the N type, the N type replaced with the P type simultaneously.

Preferably, step S₁Further comprising the steps of:

Step S₁₁, mask plate placed the back side of this P type wafer;

Step S₁₂, quicken mode that P type ion injects to 500eV-50keV and through ion with this P type ion from this P type chip back surface injection, preferably, this P type ion is accelerated to 1keV-40keV, more preferably, this P type ion is accelerated to 5keV-30keV;

Step S₁₃, form P type local doped region territory in the zone of the not masked plate resistance of P type chip back surface retaining; The square resistance in this P type local doped region territory is 10-50 Ω/; Preferably; The square resistance in this P type local doped region territory is 15-45 Ω/, and more preferably, the square resistance in this P type local doped region territory is 20-40 Ω/.

Preferably, step S₂In inject or the method for thermal diffusion forms this N type doped layer through ion; The square resistance of formed N type doped layer is 60-120 Ω/, and wherein preferably, the square resistance of this N type doped layer is 70-110 Ω/; More preferably, the square resistance of this N type doped layer is 80-100 Ω/.Those skilled in the art can select the technology that is fit to according to actual needs; For example adopt the mode of thermal diffusion or the mode of ion injection to form this N type doped layer; If the employing thermal diffusion process before carrying out thermal diffusion, need be provided with a diffusing protection layer at chip back surface; Because adopting thermal diffusion that wafer is processed is to entire wafer; In order to prevent to destroy the doped layer of other positions that processed, adopt this diffusing protection layer to stop the thermal diffusion of non-machining area, for example can adopt mask plate or use silicon nitride also to form this diffusing protection layer through PECVD method (plasma enhanced chemical vapor deposition method); If the technology that adopts ion to inject has directivity because ion injects, thus need not to be provided with the diffusing protection layer, but need high annealing, for example 700-1100 ℃, annealing time is 30 seconds to 30 minutes;

Preferably, step S₃In form coating through PECVD, the passivation layer of this coating is one or more the lamination in silica, carborundum, aluminium oxide, silicon nitride or the amorphous silicon membrane, the anti-reflection film of this coating is a silicon nitride film.The thickness of this coating is 60-150nm, and preferably, the thickness of this coating is 70-140nm, and more preferably, the thickness of this coating is 80-120nm.Surface passivation can reduce semi-conductive surface activity; The recombination rate on surface is reduced; Its main mode is the dangling bonds at saturated semiconductor surface place, reduces surface activity, increases the cleaning procedure on surface; Avoid reducing the recombination velocity of minority carrier with this owing to impurity forms the complex centre in the introducing of superficial layer.Through surface passivation, make surface recombination reduce, thereby improve effective minority carrier life time.Anti-reflection film can reduce surperficial sun reflection of light, improves the utilance of sunlight.Adopt above-mentioned coating to be the effective means that improves the solar cell photoelectric conversion efficiency.

Preferably, step S₄Middle employing silver slurry also passes through the silk screen printing method for producing surface electrode, and those skilled in the art can select other known materials and already known processes making surface electrode according to actual needs.

Preferably, step S₅In adopt silver slurry or silver-colored aluminium paste and through silk screen print method with this corresponding zone, P type local doped region territory on make backplate.

Preferably, step S₅Further comprising the steps of:

Step S₅₁, silver slurry or silver-colored aluminium paste and the oven dry that can burn passivation layer at this P type local doped region territory accurate overprinting;

Step S₅₂, press the silver slurry that does not burn passivation layer through silk screen print method plating;

Step S₅₃, the silver slurry or the silver-colored aluminium paste that can burn passivation layer be connected with the formation backplate with the silver slurry that does not burn passivation layer.The concrete realization of secondary printing is known in those skilled in the art, so do not launch narration.

Preferably, the content of aluminium is greater than 3% in the said silver-colored aluminium paste, and more preferably, the content of aluminium is greater than 5% in the said silver-colored aluminium paste, and said percentage is the mass percent that aluminium accounts for silver-colored aluminium paste total amount.

The solar cell that the present invention also provides a kind of manufacture method of using aforesaid solar cell to make, its characteristics are that it comprises:

One P type wafer;

One is arranged in the P type local doped region territory of this P type chip back surface;

One is arranged in the N type doped layer of this P type wafer surface;

Lay respectively at this back side, P type local doped region territory and this N type doped layer coating surfaces, this coating is passivation layer and anti-reflection film;

Be positioned at the surface electrode on this N type doped layer surface;

And the backplate that is positioned at this P type chip back surface;

Wherein, metallic element in said surface electrode and the backplate and the silicon eutectic in the wafer are compound, and this backplate is positioned at and this corresponding position, P type local doped region territory,

Wherein, when described P type replaced with the N type, the N type replaced with the P type simultaneously.

Preferably, the square resistance in this P type local doped region territory is 10-50 Ω/, and wherein preferably, the square resistance in this P type local doped region territory is 15-45 Ω/, and more preferably, the square resistance in this P type local doped region territory is 20-40 Ω/.

Preferably, the square resistance of this N type doped layer is 60-120 Ω/, and wherein preferably, the square resistance of this N type doped layer is 70-110 Ω/, and more preferably, the square resistance of this N type doped layer is 80-100 Ω/.

Preferably, the passivation layer of this coating is one or more the lamination in silica, carborundum, aluminium oxide, silicon nitride or the amorphous silicon membrane, and the anti-reflection film of this coating is a silicon nitride film.

In addition, only need be in said process, transposing base material and the impurity material that mixes with the mode that ion injects or diffusion is grown, then this method is equally applicable to the making of N type solar wafer, and when promptly described P type replaced with the N type, the N type replaced with the P type simultaneously.What but injected this moment on N type base wafer surface is P type ion such as boron ion, mixes to form the P type.

Measuring the photovoltaic performance of solar cell and assembly, is under stable natural daylight or simulated solar irradiation, under steady temperature, depicts its output current-voltage response, measures the photoelectric conversion efficiency of the irradiance of incident light with counting cell simultaneously.Photovoltaic energy resource system technical committee for standardization (TCST) (IEC-TC82) has stipulated standard test condition.The photoelectric conversion efficiency of the solar cell that makes according to the method described above is more than 19.25%.

Positive progressive effect of the present invention is:

1, adopt selective emitter and local back of the body field structure, reduced the contact resistance between surface electrode and the substrate, solar energy converting efficient can improve about 10%.Specifically, at present the photoelectric conversion efficiency of the solar cell of volume production is about 17.5% on the production line, and the conversion efficiency of solar cell of the present invention can be increased to about 19.25%.

2, the solar cell that makes of the present invention has bilateral structure; Can receive light in the two sides; Different with traditional single face battery like this, the back side of the solar cell that the present invention makes also can utilize the sunlight of scattering sunlight and reflection, and solar energy converting efficient can improve about 10% thus.

3, adopt ion to inject and mix, the concentration of dopant ion has obtained accurate control, and is more favourable to the efficient that improves opto-electronic conversion compared with the doping of thermal diffusion process, also reduced processing step simultaneously, reduces cost of manufacture.

Description of drawings

Fig. 1-Fig. 5 is the decomposition step sketch map of manufacturing solar cells of the present invention.

Embodiment

Provide preferred embodiment of the present invention below in conjunction with accompanying drawing, to specify technical scheme of the present invention.

Embodiment 1

With reference to figure 1, step S₁, quicken the boron ion and form P type local dopedregion territory 2 atP type wafer 1 back side through the mode that ion injects.Specifically,earlier mask plate 20 is placed the back side of thisP type wafer 1; Quickening this boron ion again injects this boron ion to 500eV and through the mode that ion injects from this P type wafer 1 back side; The last zone that just not maskedplate 20 stops atP type wafer 1 back side forms P type local doped region territory 2.The square resistance in thus obtained this P type local dopedregion territory 2 is 10 Ω/, and the arrow among Fig. 1 is depicted as the direction that ion injects, and only is for the ease of understanding, should not be construed as limitation of the present invention.

With reference to figure 2, step S₂, form N type dopedlayer 3 onP type wafer 1 surface.The method of injecting through ion in the present embodiment forms this N type dopedlayer 3; Phosphonium ion is accelerated to 500eV to be injected to carry out ion; The square resistance of formed N type dopedlayer 3 is 60 Ω/, and completion needs high annealing after injecting, and anneals 30 minutes down so that the impurity activation at 700 ℃.

With reference to figure 3, step S₃,form coating 4 at P type wafer surface and the back side, thiscoating 4 is passivation layer and anti-reflection film.Specifically, form coating through PECVD, the passivation layer of this coating is a silica, and the anti-reflection film of this coating is a silicon nitride film.The thickness of this coating is 60nm.

With reference to figure 4, step S₄,form surface electrode 5 onP type wafer 1 surface.Adopt the silver slurry in the present embodiment and pass through the silk screen printing method for producing surface electrode.

With reference to figure 5, step S₅, form backplate 6 atP type wafer 1 back side, this backplate 6 is positioned at and these 2 corresponding positions, P type local doped region territory; Step S₆, with the sintering temperature of P type wafer at 700 ℃, make the silicon eutectic in metal electrode element and the wafer compound.Wherein, step S₅In adopt the silver slurry and through silk screen print method with this corresponding zone, P type local doped region territory on make backplate.Thus, said solar cell completes.

Embodiment 2

With reference to figure 1, step S₁, quicken the boron ion and form P type local dopedregion territory 2 atP type wafer 1 back side through the mode that ion injects.Earliermask plate 20 is placed the back side of thisP type wafer 1; Then quickening the boron ion injects this boron ion to 50keV and through the mode that ion injects from thisP type wafer 1 back side; The zone that so just not maskedplate 20 stops atP type wafer 1 back side forms P type local dopedregion territory 2, and the square resistance in the P type local dopedregion territory 2 that obtains is 50 Ω/.In addition, the arrow among Fig. 1 is depicted as the direction that ion injects, and only is for the ease of understanding, should not be construed as limitation of the present invention.

With reference to figure 2-Fig. 2 a, step S₂, form N type dopedlayer 3 onP type wafer 1 surface.Wherein the method through thermal diffusion forms this N type dopedlayer 3, and the square resistance of formed N type dopedlayer 3 is 120 Ω/.With reference to figure 2a; Before carrying out thermal diffusion; Need onediffusing protection layer 21 be set at chip back surface; Because adopting thermal diffusion that wafer is processed is to entire wafer; In order to prevent to destroy the doped layer of other positions that processed; Adopt this diffusing protection layer to stop the thermal diffusion of non-machining area; Use silicon nitride and form this diffusing protection layer by PECVD method (plasma enhanced chemical vapor deposition method); After accomplishing thermal diffusion, remove this silicon nitride diffusing protection layer by the wet chemistry method.

With reference to figure 3, step S₃,form coating 4 at P type wafer surface and the back side, thiscoating 4 is passivation layer and anti-reflection film.Specifically, form coating through PECVD, the passivation layer of this coating is the lamination of carborundum, aluminium oxide, silicon nitride film, and the anti-reflection film of this coating is a silicon nitride film.The thickness of this coating is 150nm.

With reference to figure 4, step S₄,form surface electrode 5 onP type wafer 1 surface.Adopt the silver slurry and pass through the silk screen printing method for producing surface electrode.

With reference to figure 5, step S₅, form backplate at P type chip back surface, this backplate is positioned at and this corresponding position, P type local doped region territory; Step S₆, with the sintering temperature of P type wafer at 1100 ℃, make the silicon eutectic in metal electrode element and the wafer compound.Wherein, step S₅In adopt silver-colored aluminium paste and through silk screen print method with this corresponding zone, P type local doped region territory on make backplate.In order to obtain more excellent battery performance, adopt the mode of the secondary printing that is described below to make backplate: silver-colored aluminium paste and the oven dry that at first can burn passivation layer at these P type local doped region territory 2 accurate overprintings; Then press the silver slurry that does not burn passivation layer through the silk screen print method plating; The silver-colored aluminium paste that can burn passivation layer at last is connected to form backplate 6 with the silver slurry that does not burn passivation layer.The concrete realization of secondary printing is known in those skilled in the art, so do not launch narration.The content of aluminium is 3% in the said silver-colored aluminium paste, and said percentage is the mass percent that aluminium accounts for silver-colored aluminium paste total amount.Thus, said solar cell completes.

Embodiment 3

With reference to figure 1, step S₁, quicken the boron ion and form P type local dopedregion territory 2 atP type wafer 1 back side through the mode that ion injects.Specifically, step S₁Further comprising the steps of: the back side that atfirst mask plate 20 is placed thisP type wafer 1; Then quickening the boron ion injects this boron ion to 30keV and through the mode that ion injects from thisP type wafer 1 back side; The zone that not maskedplate 20 stops atP type wafer 1 back side thus forms P type local dopedregion territory 2, and the square resistance in the P type local dopedregion territory 2 of formation is 30 Ω/.In addition, the arrow among Fig. 1 is depicted as the direction that ion injects, and only is for the ease of understanding, should not be construed as limitation of the present invention.

With reference to figure 2, step S₂, form N type dopedlayer 3 onP type wafer 1 surface.Wherein quicken phosphonium ion and form this N type dopedlayer 3 to 30keV through the method that ion injects, the square resistance of formed N type dopedlayer 3 is 100 Ω/.Accomplishing needs high annealing after ion injects, and promptly under 850 ℃ temperature, anneals 10 minutes.

With reference to figure 3, step S₃,form coating 4 at P type wafer surface and the back side, thiscoating 4 is passivation layer and anti-reflection film.Specifically, form coating through PECVD, the passivation layer of this coating is the lamination in silicon nitride and the amorphous silicon membrane, and the anti-reflection film of this coating is a silicon nitride film.The thickness of this coating is 80nm.

With reference to figure 4, step S₄,form surface electrode 5 onP type wafer 1 surface.For example adopt the silver slurry and pass through the silk screen printing method for producing surface electrode.

With reference to figure 5, step S₅, form backplate 6 at P type wafer 1 back side, this backplate 6 is positioned at and these 2 corresponding positions, P type local doped region territory; Step S₆, with the sintering temperature of P type wafer at 850 ℃, make the silicon eutectic in metal electrode element and the wafer compound.Wherein, step S₅In adopt silver-colored aluminium paste and through silk screen print method with this corresponding zone, P type local doped region territory on make backplate 6.In order to obtain more excellent battery performance, adopt the mode of following secondary printing to make backplate, at first can burn the silver-colored aluminium paste and the oven dry of passivation layer at these P type local doped region territory 2 accurate overprintings; Then press the silver slurry that does not burn passivation layer through the silk screen print method plating; The silver-colored aluminium paste that can burn passivation layer at last is connected to form backplate 6 with the silver slurry that does not burn passivation layer.The concrete realization of secondary printing is known in those skilled in the art, so do not launch narration.The content of aluminium is 5% in the wherein said silver-colored aluminium paste, and said percentage is the mass percent that aluminium accounts for silver-colored aluminium paste total amount.Thus, said solar cell completes.

Embodiment 4

With reference to figure 1, step S₁, quicken phosphonium ion and form N type local doped region territory at N type chip back surface through the mode that ion injects.Specifically, at first mask plate is placed the back side of this N type wafer; Then quickening phosphonium ion injects this phosphonium ion to 500eV and through the mode that ion injects from this N type chip back surface; Form N type local doped region territory in the zone of the not masked plate resistance retaining of N type chip back surface thus, the square resistance in this N type local doped region territory is 10 Ω/.

With reference to figure 2, step S₂, form P type doped layer in N type wafer surface.The method of wherein injecting through ion forms this P type doped layer, and the square resistance of formed P type doped layer is 60 Ω/.Accomplishing needs high annealing after ion injects, and anneals 30 minutes down at 700 ℃.

With reference to figure 3, step S₃, form coating at N type wafer surface and the back side, this coating is passivation layer and anti-reflection film.Specifically, form coating through PECVD, the passivation layer of this coating is a silica, and the anti-reflection film of this coating is a silicon nitride film.The thickness of this coating is 60nm.

With reference to figure 4, step S₄, form surface electrode in N type wafer surface.Adopt the silver slurry in the present embodiment and pass through the silk screen printing method for producing surface electrode.

With reference to figure 5, step S₅, form backplate at N type chip back surface, this backplate is positioned at and this corresponding position, N type local doped region territory; Step S₆, with the sintering temperature of N type wafer at 850 ℃, make the silicon eutectic in metal electrode element and the wafer compound.Wherein, step S₅In adopt the silver slurry and through silk screen print method with this corresponding zone, N type local doped region territory on make backplate.For the mode of the secondary printing that obtains more excellent battery performance, can adopt to be described below is made backplate: silver slurry and the oven dry that at first can burn passivation layer at this N type local doped region territory accurate overprinting; Then press the silver slurry that does not burn passivation layer through the silk screen print method plating; The silver slurry that can burn passivation layer at last is connected to form backplate with the silver slurry that does not burn passivation layer.The concrete realization of secondary printing is known in those skilled in the art, so do not launch narration.Thus, said solar cell completes.

Adopting the advantage of selective emitter is to improve the open circuit voltage Voc of solar cell, short circuit current Isc and fill factor, curve factor F.F., thus make battery obtain high photoelectric conversion efficiency.And such benefit doping content height different, the diffusion depth is different in the different zone of solar cell is just brought.

Though more than described embodiment of the present invention, it will be understood by those of skill in the art that these only illustrate, protection scope of the present invention is limited appended claims.Those skilled in the art can make numerous variations or modification to these execution modes under the prerequisite that does not deviate from principle of the present invention and essence, but these changes and modification all fall into protection scope of the present invention.

Claims (12)

1. the manufacture method of a solar cell is characterized in that, it may further comprise the steps:

Step S₁, quicken P type ion and form P type local doped region territory at P type chip back surface through the mode that ion injects;

Step S₂, in the surface of P type wafer, form N type doped layer;

Step S₃, form coating on the surface of P type wafer and the back side, this coating is passivation layer and anti-reflection film;

Step S₄, form surface electrode in P type wafer surface;

Step S₅, form backplate at P type chip back surface, this backplate is positioned at and this corresponding position, P type local doped region territory;

Step S₆, with the sintering temperature of P type wafer at 700--1100 ℃, make metal electrode element and wafer eutectic compound,

Wherein, when described P type replaced with the N type, the N type replaced with the P type simultaneously.

2. the manufacture method of solar cell as claimed in claim 1 is characterized in that, step S₁Further comprising the steps of:

Step S₁₁, mask plate placed the back side of this P type wafer;

Step S₁₂, quicken mode that P type ion injects to 500eV-50keV and through ion with this P type ion from this P type chip back surface injection;

Step S₁₃, form P type local doped region territory in the zone of the not masked plate resistance of P type chip back surface retaining, the square resistance in this P type local doped region territory is 10-50 Ω/.

3. the manufacture method of solar cell as claimed in claim 1 is characterized in that, step S₂In inject or the method for thermal diffusion forms this N type doped layer through ion, the square resistance of formed N type doped layer is 60-120 Ω/.

4. the manufacture method of solar cell as claimed in claim 1 is characterized in that, step S₃In form coating through PECVD, the passivation layer of this coating is one or more the lamination in silica, carborundum, aluminium oxide, silicon nitride or the amorphous silicon membrane, the anti-reflection film of this coating is a silicon nitride film.

5. the manufacture method of solar cell as claimed in claim 1 is characterized in that, step S₄Middle employing silver slurry also passes through the silk screen printing method for producing surface electrode.

6. like the manufacture method of any described solar cell among the claim 1-5, it is characterized in that step S₅In adopt silver slurry or silver-colored aluminium paste and through silk screen print method with this corresponding zone, P type local doped region territory on make backplate.

7. the manufacture method of solar cell as claimed in claim 6 is characterized in that, step S₅Further comprising the steps of:

Step S₅₁, silver slurry or silver-colored aluminium paste and the oven dry that can burn passivation layer at this P type local doped region territory accurate overprinting;

Step S₅₂, press the silver slurry that does not burn passivation layer through silk screen print method plating;

Step S₅₃, the silver slurry or the silver-colored aluminium paste that can burn passivation layer be connected with the formation backplate with the silver slurry that does not burn passivation layer.

8. the manufacture method of solar cell as claimed in claim 7 is characterized in that, the content of aluminium is greater than 3% in the said silver-colored aluminium paste, and said percentage is the mass percent that aluminium accounts for silver-colored aluminium paste total amount.

9. solar cell that the manufacture method of using solar cell as claimed in claim 1 makes is characterized in that it comprises:

One P type wafer;

One is arranged in the P type local doped region territory of this P type chip back surface;

One is arranged in the N type doped layer of this P type wafer surface;

Lay respectively at this back side, P type local doped region territory and this N type doped layer coating surfaces, this coating is passivation layer and anti-reflection film;

Be positioned at the surface electrode on this N type doped layer surface;

And the backplate that is positioned at this P type chip back surface;

Wherein, metallic element in said surface electrode and the backplate and wafer eutectic are compound, and this backplate is positioned at and this corresponding position, P type local doped region territory,

Wherein, when described P type replaced with the N type, the N type replaced with the P type simultaneously.

10. solar cell as claimed in claim 9 is characterized in that, the square resistance in this P type local doped region territory is 10-50 Ω/.

11. solar cell as claimed in claim 9 is characterized in that, the square resistance of this N type doped layer is 60-120 Ω/.

12. solar cell as claimed in claim 9 is characterized in that, the passivation layer of this coating is one or more the lamination in silica, carborundum, aluminium oxide, silicon nitride or the amorphous silicon membrane, and the anti-reflection film of this coating is a silicon nitride film.

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