CN102569477A - Hybrid silicon solar cell and manufacturing method thereof - Google Patents

Abstract

A hybrid silicon solar cell and a manufacturing method thereof are disclosed. The invention provides a solar cell. In the solar cell, an amorphous semiconductor layer (15) is located on a back side of a crystalline silicon structure so as to form heterojunction. A first contact structure contacts with a crystalline silicon layer (14) and a second contact structure contacts with an amorphous layer (15). The invention also provides a method for forming a heterojunction solar cell. The method is characterized in that: the doped amorphous semiconductor layer (15) is formed on the crystalline silicon layer (14) which is oppositely doped; the doped amorphous semiconductor layer (15) and the crystalline silicon layer (14) form the back heterojunction; then a back side contact (16) is formed and the amorphous semiconductor layer (15) is contacted; a heavily doped region (13), whose conducting type is the same with the conducting type of the crystalline silicon layer (14), is formed at a position where the metal contact is needed to be formed with the crystalline silicon layer (14) so as to contact with the metal contact (10) which is formed subsequently.

Description

Hybrid silicon solar cells and manufacturing approach thereof

The application is to be February 8, application number in 2007 the dividing an application for the application for a patent for invention of " hybrid silicon solar cells and manufacturing approach thereof " that be 200780051088.8 (international application no is PCT/CN2007/000445), denomination of invention the applying date.

Technical field

The present invention relates to the field of silicon solar cell, particularly, the present invention relates to a kind of hybrid technology of using and make the method for this solar cell with reducing production costs to improve energy conversion efficiency.

Background technology

Based on the preparation of the solar cell of p type silicon wafer be generally earlier through such as phosphorus etc. suitably the diffusion of dopant convert the top surface of wafer to the n type; Thereby form shallow n type district (emitter) in the light-receiving side; Subsequently through the light-receiving side being carried out passivation such as hydrogenated silicon nitride; And through the back surface field that is formed by the more heavily doped p type dopant such as Al is carried out passivating back, the electric contacting layer to the silicon chip two sides metallizes then.

Yet n type Czochralski (CZ) silicon wafer has significant advantage than the p type CZ silicon wafer of common available boron-doping.This be because in standard p type CZ material since with oxygen and boron impurity in the existence, cause the generation of defective, this defective has significantly reduced the life-span of the minority carrier in the p type material.Comparatively speaking, the silicon wafer (such as the Czochralski wafer of n type or high resistivity) that does not have the silicon wafer (this can for example realize through the wafer that uses float-zone method to produce through non-CZ process) of obvious oxygen concentration or do not have obvious boron concentration can obtain higher minority carrier lifetime than the main standard p type CZ wafer that uses in the commercially producing of solar cell.Yet existing equipment of employed major part and/or process all are applicable to p type wafer manufacture and can not be used for n type wafer fabrication by development and Design in the production of commercial solar cell.And solar cell industry still must be incorporated n type CZ wafer in the production process into.In addition, for n type wafer, boron mixes and still prepares the predominant methods in its p type district (emitter).Therefore, only adopt n type wafer still can cause in battery structure, existing the zone that has high B and O concentration simultaneously.

Prior art proposes on the optical receiving surface of crystalline silicon, to grow amorphous silicon (a-Si) material layer to be used as a kind of method of avoiding boron doped p type CZ-Si district having formed heterojunction at the interface.Utilize the method, use n type CZ silicon wafer, and in silicon wafer, do not introduce any boron doped region, in entire device, to keep high minority carrier lifetime.

Yet; Utilize the method; Because the amorphous silicon in the heterostructure has low-down conductance, when heterostructure was used in the optical receiving surface place, it was infeasible that the electric current that generates is transmitted to the Metal Contact that is positioned on the amorphous silicon material along the direction that is parallel to battery surface.Must be on amorphous silicon layer shown in prior art conductive oxide layer (like indium tin oxide).This conductive oxide layer is collected the electric charge of generation and it is transmitted to the position at Metal Contact place from amorphous silicon material, thereby with mobile the reduce to minimum of electric current in amorphous silicon material.Yet conductive oxide layer obviously increases the manufacturing cost of solar cell, simultaneously also because introduced undesirable light absorption and owing to having reduced the performance of battery with the resistance loss at the interface of Metal Contact.The conductive oxide layer also causes potential durability issues, and along with wearing out of battery, said problem can reduce the performance of battery.This influence is existing complete record in document.

The minor variations of the amorphous silicon layer thickness on the optical receiving surface also can have remarkable influence to battery performance.For example, if amorphous silicon wall optimum thickness is thick slightly, then in amorphous silicon material, tangible light absorption will occur, this can not help the generation electric current of battery.This has especially reduced the response of battery to the light of shorter wavelength.On the other hand, if amorphous silicon is slightly littler than optimum thickness, then this will cause the surface passivation of relatively poor effect, the corresponding reduction of device voltage.The optimum thickness of amorphous silicon material is compromise between some these two loss mechanism of loss of some losses that reduce short wavelength response and minimizing voltage just.

Summary of the invention

According to first aspect, a kind of solar cell is provided, comprising:

I) crystal silicon layer, it has the preceding optical receiving surface and the back side;

Ii) noncrystal semiconductor layer forms heterojunction with crystal layer on the said crystal layer back side;

First contact structures that iii) contact and second contact structures that contact with said amorphous layer with said crystal layer.

This device can be formed on the silicon wafer or on the crystal silicon thin film on glass or other suitable substrate.

Second contact structures contact with amorphous layer on the back side and are positioned on this amorphous layer, and can be continuous contact layers or can be the intermittent structure such as lattice-shaped or one group of finger-shaped.In the metallized situation of back side n type autoregistration that second contact structures and heterostructure cross one another; Amorphous layer can be continuous on the whole back side; Perhaps second of amorphous layer and lattice-shaped/finger-shaped contact with the identical intermittent structure and be deposited on the back side, thereby metal contact structure is aimed at amorphous silicon layer.

First contact structures can be the intermittent structures such as lattice-shaped or one group of finger-shaped; Be positioned on the preceding optical receiving surface of crystal silicon layer; Perhaps in first contact structures and the metallized situation of the cross one another back side of heterostructure n type autoregistration; If continuously, finally can isolate with amorphous layer by first contact structures (also being positioned at the back side) that then are positioned at first on the amorphous layer on the whole back side for amorphous layer.In this case, need handle, make it extend through the amorphous layer of being separated by to touch the back side of crystal silicon layer to first contact.In the latter's situation, will go up overleaf at interval for one in first and second contact structures and carry out electrically contacting with equal the distributed of crystal region and amorphous area of realizing.

According to second aspect, a kind of method that on relative with the preceding optical receiving surface of the silicon solar cell body back side, forms heterojunction comprises:

A) noncrystal semiconductor layer of formation phase contra-doping on the doped crystal silicon layer back side;

B) form the back side contact that contacts with above-mentioned noncrystal semiconductor layer then;

C) on front surface, need the position formation of Metal Contact and the heavily doped region of crystal silicon layer identical conduction type;

D) form the Metal Contact that contacts with above-mentioned heavily doped region;

This method can silicon wafer be grown in glass or other suitable substrate on crystal silicon thin film on carry out.Preferably, in the situation of using wafer, the silicon wafer of doping is a n type silicon wafer, and this n type silicon wafer is at first removed surface damage, making herbs into wool and cleaning.The front surface of wafer preferably carries out the PECVD deposited silicon nitride layer with containing phosphorus dopant.So can under silicon nitride layer, introduce the electronics accumulation layer.

Noncrystal semiconductor layer is amorphous silicon hydride, hydrogenated amorphous silicon carbide or hydrogenated amorphous sige alloy preferably.We will use amorphous silicon hydride as an example hereinafter.

Second contact structures are preferably formed by layer of metal or multiple layer metal such as through sputtered aluminum.

First contact structures are preferably by Ni, Cu or the Ag heavy doping n in n type crystalline silicon wafer or n type crystalline silicon film ⁺⁺Plated metal is processed in the district.Heavy doping n ⁺⁺The district preferably produces through the laser doping of phosphorus dopant.

Preferably, before chemical plating/plated metal contact, through nickel, copper then for appearing silver in one's mind, is used before this plating step of surface atom of silver replacement copper, to n then such as earlier ⁺⁺The district is cleaned.Then preferably, carry out metal sintering (this does not also carry out if after Ni electroplates).

Can be as an alternative; In the situation that adopts silicon wafer; Front surface first contact structures form before heterojunction forms overleaf, in this case, need on the back side of crystalline silicon, to form interim oxide skin(coating); It can be removed before the amorphous silicon layer that forms heterojunction, and then carried out the back metal contact.

In another alternative, the front surface structure forms through following:

A) form the preparatory passivation layer of front surface through nitrogenize or oxidation earlier;

B) deposit the n type hydrogenated amorphous silicon layer that adds phosphorus dopant again;

C) deposit the silicon nitride layer that adds optional phosphorus dopant then;

On the front surface structure that produces by said method, add first contact structures as described above subsequently.

With heterojunction structure back side n type autoregistration metallization contact structures heterojunction arranged in a crossed manner in; First contact structures that contact with crystal silicon wafer or crystal film are formed on the back side of crystal silicon wafer or crystal film; And when amorphous layer is when being provided with continuously; The amorphous silicon layer that then sees through the back side through laser doping forms, perhaps when amorphous layer be discontinuous when being provided with, then laser doping sees through the gap formation in the amorphous silicon layer of the back side.Last overleaf formation first contact contacts with second and comprises the steps:

A) on the hydrogenated amorphous silicon layer that mixes, form second contact structures that have positive bus bar with open patterns;

B) form preceding dielectric layer and back dielectric layer through the plasma reinforced chemical vapour deposition (PECVD) that contains phosphorus dopant, utilize mask plate that above-mentioned cathode metal busbar is exposed such as silicon nitride, silicon dioxide or carborundum;

C) utilize laser doping to go up overleaf and form the heavy doping n that crosses one another with pectination washing district ⁺⁺The district;

D) at above-mentioned heavy doping n ⁺⁺Form first Metal Contact in the district.

Preferably, in the heterojunction device of the back side of this form, forming the process that electrically contacts comprises:

A) overleaf through metal formation second contact of sputter such as aluminium, have the back side contact of the pectination pattern of positive bus bar with formation;

B) utilize the laser doping method to form the n that crosses one another and be provided with above-mentioned pectination metal area overleaf ⁺⁺The district;

C) to said n ⁺⁺The district carries out chemical cleaning, and then through the for example first nickel of chemical plating/plating, copper for appearing silver in one's mind, is replaced this step of surface atom of copper to use silver, to form first contact structures that contact with crystal silicon layer then then; And

D) carry out metal sintering.

In the situation that adopts silicon wafer, after forming the back side contact that contacts with silicon wafer, contain the depositing hydrogenated silicon nitride of PECVD of phosphorus dopant at the front surface of silicon wafer.This can form the electronics accumulation layer under silicon nitride layer.

Use aforesaid laser doping method; Through back side n type autoregistration metallization process, on the n type crystalline silicon film that is arranged on the glass substrate, form to contain to be and intersect the metallize manufacture method of solar cell of contact structures of the back side n type autoregistration that is provided with and comprise with heterojunction structure:

A) on glass substrate, form crystal silicon thin film;

B) on the back side of the crystal silicon layer that exposes, grow amorphous silicon layer to form heterojunction;

C) form second contact structures through the metal of sputter such as aluminium overleaf, have the back side contact of the pectination pattern of positive bus bar with formation;

D) go up the n that formation and above-mentioned pectination metal area cross one another overleaf with the laser doping method ⁺⁺The district;

E) at n ⁺⁺Form first contact structures in the district.

In this case, preferably, before the grown crystal silicon layer, add the front surface silicon nitride layer of phosphorus dopant in glass substrate growth earlier.In addition, this preferred process and the similar process that adopts doped silicon wafer.

Description of drawings

To describe embodiments of the invention with reference to accompanying drawing now, in the accompanying drawings:

Fig. 1 schematically shows the back side heterojunction structure with front surface autoregistration Metal Contact;

Fig. 2 schematically shows the intermediate steps structural diagrams in a kind of method that forms the back side heterojunction structure with front surface autoregistration metallization contact;

Fig. 3 schematically shows a kind of back side n type autoregistration metallization contact structures and back side heterojunction structure and is and intersects the structural diagrams of setting;

Fig. 4 schematically shows the sketch map that utilizes laser doping to form the heterojunction solar cell structure with cryogenic media layer of contact structures through front surface autoregistration metallization;

Fig. 5 schematically show a kind of on the n type crystalline silicon film on the glass substrate, form to be with heterojunction structure intersects the metallize solar battery structure sketch map of contact structures of the back side n type autoregistration of setting.

Embodiment

With reference to accompanying drawing, show some embodiment of the solar cell that adopts back side heterostructure.

In these embodiment, heterojunction is positioned at the back side, has avoided when heterojunction is positioned on light-receiving (preceding) face, need using conductive oxide layer to realize cross conduction, and has reduced the influence of device performance for the thickness sensitivity of the amorphous silicon layer in the heterostructure.Among the described herein embodiment, light at first through crystalline silicon region, has been avoided the situation of short-wavelength light through amorphous silicon layer basically.This also helps to realize the utilization of metal on the whole back side of amorphous silicon layer, has therefore avoided using conductive oxide layer to conduct the electric current of the direction that is parallel to battery surface.

Yet the use of heterojunction has increased near the travel distance of the charge carrier that optical receiving surface, produces overleaf, because these charge carriers must advance to the collection knot that is positioned at the back side.Therefore, preferably use high resistivity and high-quality wafer (no matter this structural design is used for n type wafer still is p type wafer) or crystal region is fabricated to film or both furthermore.If use n type wafer; Then need be to the contact patterns (otherwise crossing one another with contacting of heterojunction overleaf) of n type material to its front surface; Heavy doping below the Metal Contact is necessary thus; So that minimize contact resistance, and minimize metal/silicon interface is to the influence of device dark electric current.Before the required amorphous silicon material of deposition heterojunction,, should avoid the use of high-temperature heat treatment for the quality of avoiding wafer surface or wafer material descends.After deposition of hydrogenated amorphous silicon, subsequently device handle also should with existing structure compatible to avoid heterojunction and degenerate or the decline of surface passivation quality.

For the high resistivity wafer; Under the situation of the front surface diffusion that does not have independent identical polar; It is a challenge that majority carrier is transmitted to n type metal (first) contact (such as the front surface Metal Contact) in the chip body; In this case, the use of the heterojunction on the diffusion of the front surface of said independent identical polar and the back side is incompatible.Since from the loss of the hydrogen in the amorphous silicon or and even such as through temperature required down crystallization and to the infringement of amorphous silicon material, so after heterojunction forms overleaf, can not use traditional front surface to spread; On the other hand; Before forming back side heterojunction; Traditional front surface diffusion also is infeasible; This is because heat treatment process also can have problems during can bringing influence and associative operation to the back side overleaf, gets into the surface such as producing defective, surperficial roughening, surface contamination, surface oxidation or undesirable dopant or other diffusion of impurities.Adopt any current commercial batteries technology (such as the solar cell of the solar cell of silk screen printing, flush type contact, point contact solar cell etc.) to carry out the Metal Contact scheme and can not realize above-mentioned full content usually; Need be mainly due to them by high-temperature heat treatment process; Be to combine with the diffusion process of necessity, or the sinter bonded that contacts with additional metals.

With reference to Fig. 1; Above-mentioned amorphous silicon/crystalline silicon heterojunction structure 17 uses at the place, the back side of battery; And self aligned chemical plating (or plating) front surface metallization contact 10 is formed on the heavily doped region 13, and this heavily doped region 13 is through using as being formed in the laser doping described in the US patent 6429037 by Wenham and Green.Yet, because it must be used for majority carrier is used in combination from the technology that their generation point is transmitted to the position at metal place, possibly be not enough so do like this.Incompatible such as conventional diffusion process of in fact in all commercial solar cells of making, using at present and the back side heterojunction design among the present invention, existing at present three compatible possibilities (in the battery of commerce manufacturing, not using at present) are through confirming to be enough to provide necessary majority carrier conduction.

In first possibility; Describe in Australian provisional application No.AU2005926552 and 2005926662 " Low area screen printed metal contact structure and method " (being incorporated into this) like Wenham etc. through reference; The transparent conductor of laser doping can be used in and conducts the current to self aligned Metal Contact; Wherein preferably, this transparent conductor and Metal Contact line omnidirectional distribution.In this structure; The laser doping that contacts of the transparent conductor that is useful on and autoregistration metallization can both in single process, carry out; As long as use the different laser condition to transparent conductor; Therefore stacked thus dielectric layer and/or ARC and/or diffuse source can still can not played the mask effect to silicon face at electroplating process subsequently by apparent damage.Can be as an alternative, transparent conductor also can form before dielectric layer/anti-reflecting layer/surface passivation layer deposition, thereby their surface is protected in the plating process that forms with laser doping after the autoregistration metallization contacts.

In second possibility; Can be in the surface by utilizing electrostatic effect; The electric charge of for example painstakingly introducing remarkable energy level is (if use n type wafer then be positive charge; If use p type wafer then be negative electrical charge) in surface dielectric layer, thus produce accumulation layer in this surface, to strengthen the conduction of majority carrier to the position of Metal Contact or transparent conductor.For example, the silicon nitride layer of the atomic hydrogen of high level being introduced Silicon-rich can be realized this result.Other element also can add positive charge in this dielectric layer.If that introduces is suitable, then these electrostatic effects can provide surface passivation very efficiently with dielectric layer.Can have suitable broad-band gap and also can be used to cause band curvature as an alternative, produce accumulation layer, improve the transverse conductivity of n type wafer with this near surface with the semi-conducting material that suitably mixes.The method that is equal to therewith also can be used for p type wafer, and its holes accumulates to the surface, has improved the transverse conductivity of majority carrier, and in this case, majority carrier is the hole.The doping amorphous silicon hydride is exactly one of wide bandgap semiconductor materials with back side heterojunction compatibility.In this material, the atomic hydrogen of release can combine with the elimination mid gap state with the silicon dangling bonds at the interface, thereby has strengthened surface passivation effect.In addition; Through some elemental diffusion such as nitrogen or oxygen; The sub-surface district of crystalline silicon substrate can convert dielectric layer to, thereby the silicon dangling bonds are moved apart original surface of crystalline silicon and will reduce to minimum owing to not cleaning any negative effect that the surface contaminant leave over causes fully.

In the 3rd possibility, realize that through use rapid thermal treatment (RTP) or laser doping the large tracts of land diffusion of whole front surface also can be played effect, these thermal effects will can not make the heterojunction at the back side degenerate.This technology can be used for back side heterostructure with the autoregistration metallization scheme, and at this, front surface rapid thermal treatment or laser carry out before being diffused in the heavily doped region that laser doping formation contacts with plating.In this scheme, can same dopant source be used in the laser doping of front surface diffusion and autoregistration metallization and/or transparent conductor.For example, the phosphorus source can add the silicon nitride ARC, then as the metallized phosphorus of front surface diffusion, transparent conductor and autoregistration source.

Using resistivity in the situation of the n type wafer of the medium resistance rate of 1-5 Ω-cm, the square resistance rate of wafer itself is enough to avoid to the transverse conductivity of the above-mentioned majority carrier that is used for the strengthening wafer demand with the method for the collection that promotes first Metal Contact.These wafers have sufficiently high minority carrier lifetime, and are as long as wafer thickness is not thicker than 200 microns, then compatible with the back side heterojunction device design that is provided.

Realize the exemplifying embodiment of back side heterojunction structure.

1. form back side heterojunction, form front surface autoregistration metallization contact (with reference to Fig. 1) through laser doping subsequently and comprise the steps:

A) n type silicon wafer 14 is removed surface damage, making herbs into wool and cleaning;

B) p type hydrogenated amorphous silicon layer 15 of deposition on chip back surface;

C) utilize the PECVD deposition to contain the silicon nitride 11 of phosphorus dopant at front surface, under silicon nitride layer 11, introduce electronics accumulation layer 12 with this;

D) metal 16 of sputter such as aluminium forms the back side (second) contact;

E) on front surface, need the position of Metal Contact to utilize laser doping to produce n ⁺⁺District 13;

F) chemical cleaning n ⁺⁺District 13, chemical plating/plated metal 10 again, such as first nickel plating, copper facing then, silver is appeared in plating in one's mind then, with the surface atom of silver replacement copper;

G) metal sintering (this does not also carry out if after nickel is electroplated)

2. forming back side heterojunction then through laser doping formation front surface autoregistration metallization contact (with reference to Fig. 2) comprises the steps:

A) n type silicon wafer 14 is removed surface damage, making herbs into wool and cleaning;

B) go up growth temporary protection layer overleaf, as with PECVD growing silicon oxide 18;

C) as in the above-mentioned example 1, utilize the PECVD deposition to contain the silicon nitride 11 of phosphorus dopant at front surface, under silicon nitride layer 11, introduced electronics accumulation layer 12;

D) on front surface, need the position of Metal Contact to produce n with laser doping ⁺⁺District 13;

E) remove back-protective layer 18 (see figure 2) and clean the back side then;

F) on chip back surface, deposit p type hydrogenated amorphous silicon layer 15 then;

G) metal 16 of sputter such as aluminium overleaf then forms the back side (second) contact;

H) chemical cleaning n ⁺⁺District 13, chemical plating/plated metal 10 again, such as first nickel plating, copper facing then, silver is appeared in plating in one's mind then, with the surface atom of silver replacement copper;

I) metal sintering (this does not also carry out if after nickel is electroplated)

3. the back side n type autoregistration metallization that crosses one another through laser doping formation and back side heterostructure contacts (with reference to Fig. 3) and comprises the steps:

A) n type silicon wafer 34 is removed surface damage, making herbs into wool and cleaning;

B) deposition (continuous or with pectination pattern intermittently) p type hydrogenated amorphous silicon layer 35 on chip back surface then;

C) metal 36 of sputter such as aluminium on amorphous silicon layer 35 forms the intermittently back side contact of pattern of pectination that has positive bus bar;

D) utilize the PECVD deposition to contain the silicon nitride layer 31 of phosphorus dopant at the front surface and the back side; Wherein, during deposited silicon nitride, utilize mask that the cathode metal busbar is exposed overleaf;

E) go up with laser doping overleaf and produce n ⁺⁺District 33 is with pectination washing district 36 setting that crosses one another;

F) chemical cleaning n ⁺⁺District 33, chemical plating/plated metal 30 again, such as first nickel plating, copper facing then, silver is appeared in plating in one's mind then, with the surface atom of silver replacement copper;

G) metal sintering (this does not also carry out if after Ni electroplates)

4. form back side heterojunction structure, utilize laser doping and low-temperature dielectric layer to form front surface autoregistration metallization subsequently and contact (with reference to Fig. 4), comprise the steps:

A) n type silicon wafer 44 is removed surface damage, making herbs into wool and cleaning;

B) deposition p type hydrogenated amorphous silicon layer 45 on chip back surface;

C) the metal 46 formation back sides of sputter such as aluminium contact;

D) form the preparatory passivation layer 47 of front surface through nitrogenize or oxidation;

E) deposit the n type hydrogenated amorphous silicon layer 48 that contains phosphorus dopant at front surface;

F) contain 41 layers of the low temperature silicon nitrides of phosphorus dopant in front surface deposition;

G) on front surface, need the position of Metal Contact to produce n with laser doping ⁺⁺District 43;

H) chemical cleaning n ⁺⁺District 43, chemical plating/plated metal 40 again, such as first nickel plating, copper facing then, silver is appeared in plating in one's mind then, with the surface atom of silver replacement copper;

I) metal sintering (this does not also carry out if after Ni electroplates)

5. the back side on the film n type crystalline silicon on the glass substrate utilizes laser doping to form back side n type autoregistration metallization contact, with back side heterojunction structure (with reference to Fig. 5) arranged in a crossed manner each other, may further comprise the steps:

A) on glass substrate 59, contain phosphorus dopant silicon nitride layer 51 with the PECVD deposition;

B) growing n-type film crystal silicon layer 54 on the silicon nitride layer on the glass substrate 51;

C) on the back side of film crystal silicon layer, deposit p type hydrogenated amorphous silicon layer 55 then;

D) metal 56 of sputter such as aluminium then forms the back side contact of the pectination pattern that has positive bus bar;

E) utilize mask that the cathode metal busbar is come out and contain the silicon nitride 61 of phosphorus dopant overleaf with PECVD deposition.Add enough phosphorus dopants, thereby produce the required n of autoregistration first Metal Contact in laser doping subsequently, to make n type dopant cover p type dopant ⁺⁺The district;

F) produce n overleaf with laser doping ⁺⁺District 53, and with pectination washing district 56 distribution that crosses one another;

G) chemical cleaning n ⁺⁺District 53, chemical plating/plated metal 50 subsequently, such as first nickel plating, copper facing then, silver is appeared in plating in one's mind then, with the surface atom of silver replacement copper;

H) metal sintering (this does not also carry out if after Ni electroplates)

In a word; The solar cell that is based on crystalline silicon mentioned above, this solar cell have be positioned at the back side be used to realize that the light induced electron hole is formed for the laser doping regional area of majority carrier conduction to the non crystal heterogeneous agglomeration that separates and at crystalline silicon material.

Utilize Diffusion mechanisms of impurities to introduce to comprise preceding (light-receiving side) passivating structure among some embodiment with the dopant of wafer identical polar; To produce and interface than the light dope wafer, this interface is moved in the body silicon to the silicon front surface in the passivation dielectric film deposition before.

Utilize Diffusion mechanisms of impurities to introduce adding among other embodiment and comprise preceding (light-receiving side) passivating structure like nitrogen or oxygen dopant; With the interface of generation with wafers doped; This interface is moved in the body silicon before the deposition of hydrogenated amorphous silicon passivation layer, with the post-passivation low-temperature dielectric layer of silicon nitride for example.

Some embodiment also through carry out at silicon front surface regional area laser doping introduce local before electrode; Dielectric passivation layer or amorphous silicon layer above destroying simultaneously; So that expose the silicon face after the laser doping; Utilize the autoregistration metallization to form Metal Contact at this exposed region then, the remainder that the not broken simultaneously passivation layer that encircles has been covered optical receiving surface avoids forming Metal Contact.

Also can use one or more layers metal directly to be deposited on the said amorphous silicon film, among the embodiment as rear electrode.

In the structure that substitutes, some embodiment can go up overleaf add cross one another just/negative electrode structure, this electrode structure is processed through the metallization of on the rear electrode of patterning, carrying out laser doping and carry out subsequently.

In certain embodiments; Preceding contact also can be adopted the transparent conductor that combines and form through laser doping and above-mentioned preceding metallization scheme; This transparent conductor is vertical or angled with the Metal Contact line, thereby the heavily doped region under the transparent conductor and first Metal Contact is intersected.

Need be understood that under situation about not departing from like the spirit of broadly described embodiments of the invention or scope, the present invention is carried out many distortion to those of skill in the art and/or modification is all protection scope of the present invention.These embodiment be merely exemplary but not in order to the restriction the present invention.

Claims (19)

1. solar cell comprises:

I) crystal silicon layer, it has the preceding optical receiving surface and the back side;

Ii) noncrystal semiconductor layer forms heterojunction at the back side and the said crystal silicon layer of said crystal silicon layer;

First contact structures that iii) contact and be positioned on the said noncrystal semiconductor layer and second contact structures that contact with said noncrystal semiconductor layer with said crystal silicon layer,

Wherein, said first contact structures are positioned at the back side of said crystal silicon layer, with the setting that crosses one another of said noncrystal semiconductor layer and said second contact structures.

2. the solar cell described in claim 1, wherein,

Said second contact structures and/or first contact structures comprise one group of finger-shaped structure that links each other that contact material forms.

3. the solar cell described in claim 1, wherein,

Said first contact structures comprise with the back side autoregistration metallization that is provided with that crosses one another of said heterojunction and said second contact structures and contacting.

4. solar cell as claimed in claim 1, wherein,

Said crystal silicon layer comprises silicon wafer or is positioned at the crystal silicon thin film on the glass substrate.

One kind with the front surface of silicon solar cell matrix or optical receiving surface opposing backside surface on form the method for heterojunction, comprising:

A) noncrystal semiconductor layer of formation phase contra-doping on the back side of doped crystal silicon layer;

B) form the back side second contact, to contact with said noncrystal semiconductor layer;

C) on said crystal silicon layer, need the position formation of Metal Contact and the heavily doped region of said crystal silicon layer identical conduction type;

D) form metal first contact that contacts with said heavily doped region,

Wherein, said first contact be formed on the said back side and with the setting that crosses one another of said heterojunction.

6. method as claimed in claim 5, wherein,

Said noncrystal semiconductor layer is amorphous silicon hydride, hydrogenated amorphous silicon carbide or hydrogenated amorphous sige alloy.

7. like each described method of claim 5, wherein,

Said crystal silicon layer is a n type crystalline silicon layer, and said first contact is passed through the heavy doping n of one or more metal-plated in said n type crystalline silicon layer ⁺⁺Form in the district.

8. method as claimed in claim 7, wherein,

The metal that is plated is selected from one or more of Ni, Cu and Ag.

9. method as claimed in claim 7, wherein,

Said first contact is to pass back side amorphous silicon layer and cover the insulating barrier formation that is used as dopant source on the said amorphous silicon layer back side; Or passing gap formation as the insulating barrier and the back side amorphous silicon layer of dopant source, said insulating barrier forms said n through carrying out laser doping ⁺⁺The district.

10. method as claimed in claim 9, wherein,

First contact metallization passes through at said n ⁺⁺The opening and the said n that on said insulating barrier, form during the formation in district ⁺⁺District's autoregistration.

11. method as claimed in claim 5, wherein,

Said first contact of formation and said second contacts also and comprises on the said back side:

E) on the noncrystal semiconductor layer of said doping, form said second contact with open patterns with positive bus bar;

F) form preceding dielectric layer and back dielectric layer through plasma reinforced chemical vapour deposition (PECVD), add phosphorus dopant, said positive bus bar is exposed through mask;

G) form the n that contacts the setting that crosses one another with said second through laser doping ⁺⁺The district;

H) at said n ⁺⁺Form Metal Contact in the district.

12. method as claimed in claim 11, wherein,

Dielectric layer and back dielectric layer are formed one or more layers silicon nitride, silica or carborundum before said.

13. method as claimed in claim 11, wherein,

The process that forms said contact further comprises:

I) on the said back side, form said second contact, have the said back side second contact of the pectination pattern of positive bus bar with formation through metal sputtering;

J) use laser doping on the said back side, to form the n that crosses one another and be provided with pectination washing district ⁺⁺The district;

K) the said n of chemical cleaning ⁺⁺The district, chemical plating/plated metal subsequently is to form said first contacting of contacting with said crystal silicon layer; And

L) the said metal of sintering.

14. like each described method in the claim 7 to 13, the front surface that further is included in said crystal silicon layer is provided with dielectric layer.

15. method as claimed in claim 14, wherein,

This dielectric layer is formed one or more layers silicon nitride, silica or carborundum, and said dielectric layer is to form through the PECVD deposition that adds phosphorus dopant, and generating under the said dielectric layer has the electronics accumulation layer.

16. like claim 5 or 11 or 13 described methods, wherein,

Form the front surface structure through following steps:

M) form the preparatory passivation layer of front surface through nitrogenize or oxidation;

N) form the front surface hydrogenated amorphous siliceous deposits of n type and add phosphorus dopant;

O) form front surface silicon nitride deposition.

17. method as claimed in claim 5, wherein,

Said crystal silicon layer comprises the n type crystalline silicon film that is positioned on the glass substrate, and said method comprises:

A) on glass substrate, form crystal silicon thin film;

B) form amorphous silicon layer, the back side that exposes with said crystal silicon thin film forms heterojunction;

C) form said second contact at the said back side through splash-proofing sputtering metal, have the said back side second contact of the pectination pattern of positive bus bar with formation;

D) on the said back side, utilize laser doping to produce n ⁺⁺The district, said n ⁺⁺District and the distribution that crosses one another of pectination washing district;

E) at said n ⁺⁺Form first Metal Contact in the district.

18. method as claimed in claim 17, wherein,

Before using said crystal silicon layer, on said glass substrate, generate the front surface silicon nitride layer.

19. like claim 5 to 13,15,17 to 18 each described methods, wherein,

The metal of said second contact is an aluminium, and it forms through sputter.

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