CN110838528A - A post-doped N-type contact passivation battery - Google Patents

Abstract

The invention discloses a post-doping type N-type contact passivation battery, which comprises an N-type silicon wafer, a front structure and a back structure. The back structure includes a tunneling layer, an n+ polysilicon layer, a back passivation layer and a back metal electrode. The penetration layer, the n+ polysilicon layer and the back passivation layer are arranged in sequence along the direction of the N-type silicon wafer. The N-type contact passivation cell also includes an intrinsic polysilicon layer and an n++ heavily doped region. The intrinsic polysilicon layer is arranged on the n+ polysilicon. Between the layer and the back passivation layer, the n++ heavily doped region runs through the intrinsic polysilicon layer, the inner end of the n++ heavily doped region is in contact with the n+ polysilicon layer, the back metal electrode penetrates the back passivation layer, and the inner end of the back metal electrode is in contact with the n+ polysilicon layer. The outer end contacts of the n++ heavily doped regions. The invention can not only reduce the absorption of free carriers on the backside, improve the double-sided ratio of the double-sided battery, but also eliminate the metal recombination in the metallized area, and further improve the conversion efficiency of the N-type contact passivation battery.

Description

A post-doped N-type contact passivation battery

technical field

The invention designs the field of solar cells, in particular to a post-doped N-type contact passivation cell.

Background technique

Referring to FIG. 1 , an N-type contact passivation cell in the prior art includes an N-type silicon wafer 11 , a front structure disposed on the front side of the N-type silicon wafer 11 , and a backside disposed on the back side of the N-type silicon wafer 11 . Structure, the front structure includes a p+ doped layer 12, a front passivation layer 13 and a front metal electrode 14, the p+ doped layer 12 and the front passivation layer 13 are arranged in sequence along the direction of the N-type silicon wafer 11, and the front metal electrode 14 Passing through the front passivation layer 13 , the inner end of the front metal electrode 14 is in contact with the p+ doped layer 12 , and the back structure includes a tunnel layer 15 , an n+ polysilicon layer 16 , a back passivation layer 17 and a back metal electrode 18 , the tunnel layer 15 , the n+ polysilicon layer 16 and the back passivation layer 17 are arranged in sequence along the direction of getting away from the N-type silicon wafer 11, the back metal electrode 18 penetrates the back passivation layer 17, the inner end of the back metal electrode 18 and the outer end of the n+ polysilicon layer 16 touch. During fabrication, a 1-2nm tunneling layer is first deposited, and then an n+ polysilicon layer of uniform thickness is deposited. In order to ensure that in the subsequent metallization process, the metal paste will not burn through the n+ polysilicon layer. The thickness must be greater than 100 nm, but the larger the thickness of the n+ polysilicon layer, the more severe the free carrier absorption on the backside.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a post-doped N-type contact passivation cell, which can not only reduce the absorption of free carriers on the backside, improve the bifacial ratio of the double-sided cell, but also eliminate the metal recombination in the metallized area, and further improve the N-type contact passivation cell conversion efficiency.

In order to achieve the above object, the technical solution adopted in the present invention is: a post-doped N-type contact passivation cell, comprising an N-type silicon wafer, a front surface structure arranged on the front side of the N-type silicon wafer, and a front surface structure arranged on the front side of the N-type silicon wafer. The backside structure on the backside of the N-type silicon wafer, the backside structure includes a tunneling layer, an n+ polysilicon layer, a backside passivation layer and a backside metal electrode, the tunneling layer, the n+polysilicon layer and the backside passivation The passivation layers are arranged in sequence along the direction away from the N-type silicon wafer, the N-type contact passivation cell further includes an intrinsic polysilicon layer and an n++ heavily doped region, and the intrinsic polysilicon layer is arranged on the n+ polysilicon layer Between the back passivation layer, the n++ heavily doped region penetrates the intrinsic polysilicon layer, the inner end of the n++ heavily doped region is in contact with the n+ polysilicon layer, and the back metal electrode penetrates the In the backside passivation layer, the inner end of the backside metal electrode is in contact with the outer end of the n++ heavily doped region, wherein the thickness of the n+ polysilicon layer is 10-50nm, and the thickness of the intrinsic polysilicon layer is 50-250nm.

Further, the dopant of the n++ heavily doped region is phosphorus.

Further, the n++ heavily doped region is an n++ heavily doped region formed by a laser doping process.

Further, the tunneling layer is a tunneling layer formed by deposition.

Further, the n+ polysilicon layer is an n+ polysilicon layer formed by deposition.

Further, the intrinsic polysilicon layer is an intrinsic polysilicon layer formed by deposition.

Further, the front structure includes a p+ doped layer, a front passivation layer and a front metal electrode, and the p+ doped layer and the front passivation layer are arranged in sequence along the direction of moving away from the N-type silicon wafer, so The front metal electrode penetrates through the front passivation layer, and the inner end of the front metal electrode is in contact with the p+ doped layer.

Further, the dopant of the p+ doped layer is boron tribromide.

Further, the p+ doped layer is a p+ doped layer formed by means of air-carrying dopants.

Further, the front passivation layer and the back passivation layer are both anti-reflection passivation films.

Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art: the post-doped N-type contact passivation cell disclosed in the present invention, for the N-type contact passivation double-sided cell, the current backside is limited by the metal paste Due to the limitation of material burn-through, the photoelectric conversion efficiency of industrial cells is still low. Through the design of the combination of n+ doping on the back and intrinsic polysilicon, the absorption of free carriers on the back is reduced, and the metal contact and the metal region are recombined, which is further improved. N-type contact passivation for bifacial cell efficiency.

Description of drawings

1 is a schematic structural diagram of an N-type contact passivation cell in the prior art;

FIG. 2 is a schematic structural diagram of an N-type contact passivation cell in the present invention.

Among them: 11, 21, N-type silicon wafer; 12, 22, p+ doped layer; 13, 23, front passivation layer; 14, 24, front metal electrode; 15, 25, tunneling layer; 16, 26, n+ Polysilicon layer; 17, 27, backside passivation layer; 18, 28, backside metal electrode; 291, intrinsic polysilicon layer; 292, n++ heavily doped region.

Detailed ways

The present invention is further described with reference to the accompanying drawings and embodiments:

Example 1

Referring to FIG. 2, as shown in the legend, a post-doped N-type contact passivation cell includes an N-type silicon wafer 21, a front-side structure disposed on the front side of the N-type silicon wafer, and a front-side structure disposed on the N-type silicon wafer The back structure on the back side,

The front structure includes a p+ doped layer 22, a front passivation layer 23 and a front metal electrode 24. The p+ doped layer 22 and the front passivation layer 23 are arranged in sequence along the direction of the N-type silicon wafer 21, and the front metal electrode 24 runs through the front side. The passivation layer 23 and the inner end of the front metal electrode 24 are in contact with the p+ doped layer 22 .

The backside structure includes a tunneling layer 25 , an n+ polysilicon layer 26 , a backside passivation layer 27 and a backside metal electrode 28 . The tunneling layer 25 , the n+ polysilicon layer 26 and the backside passivation layer 27 are in sequence along the direction of the N-type silicon wafer 21 . Arrangement, the N-type contact passivation cell further includes an intrinsic polysilicon layer 291 and an n++ heavily doped region 292, the intrinsic polysilicon layer 291 is provided between the n+ polysilicon layer 26 and the backside passivation layer 27, and the n++ heavily doped region 292 runs through In the intrinsic polysilicon layer 291 , the inner end of the n++ heavily doped region 292 is in contact with the n+ polysilicon layer 26 , the backside metal electrode 28 penetrates the backside passivation layer 27 , and the inner end of the backside metal electrode 28 is in contact with the outer end of the n++ heavily doped region 292 contact, wherein the thickness of the n+ polysilicon layer 26 is 10-50 nm, and the thickness of the intrinsic polysilicon layer 291 is 50-250 nm.

In a preferred implementation manner in this embodiment, the dopant of the n++ heavily doped region 292 is phosphorus.

In a preferred implementation manner in this embodiment, the n++ heavily doped region 292 is an n++ heavily doped region formed by a laser doping process.

In a preferred implementation manner in this embodiment, the tunneling layer 25 is a tunneling layer formed by deposition.

In a preferred implementation manner in this embodiment, the n+ polysilicon layer 26 is an n+ polysilicon layer formed by deposition.

In a preferred implementation manner in this embodiment, the intrinsic polysilicon layer 291 is an intrinsic polysilicon layer formed by deposition.

In a preferred implementation manner in this embodiment, the dopant of the p+ doped layer 22 is boron tribromide.

In a preferred implementation manner in this embodiment, the p+ doped layer 22 is a p+ doped layer formed by means of air-carrying dopants.

In a preferred implementation manner in this embodiment, the front passivation layer 23 and the back passivation layer 27 are both anti-reflection passivation films.

The following introduces the preparation method of the N-type contact passivation battery of the present invention, comprising the following steps:

Step1: N-type original silicon wafer double-sided alkali texturing;

Step2: Use BBr3 to diffuse the N-type silicon wafer after alkali texturing to form a P+ layer;

Step3: single-sided etching to remove the P+ layer on the back;

Step4: deposit a tunnel layer (SiO2/a-Si:H, etc.) on the backside;

Step5: In-situ deposition of 10-50nm n+ polysilicon layer on the backside;

Step6: The same process as Step5, except that the phosphorus source is not connected, continue to deposit a 50-250nm intrinsic polysilicon layer, and finally deposit a layer of phosphorus source;

Step7: Use the laser doping process to locally re-dope the area that needs to be metallized to form an n++ region;

Step8: Double-sided cleaning and annealing, on the one hand, activate the in-situ doped phosphorus, and on the other hand eliminate laser damage;

Step9: Deposition anti-reflection passivation film on both sides;

Step10,: The backside is metallized, and the metal paste printing area corresponds to the Step7 laser doping area;

Step11: Sintering to complete the preparation of N-type contact passivation double-sided cells.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The utility model provides a back doping formula N type contact passivation battery, includes the N type silicon chip, locates the front structure of N type silicon chip front one side and locates the back structure of N type silicon chip back one side, the back structure includes tunnel layer, N + polycrystalline silicon layer, back passivation layer and back metal electrode, the tunnel layer, N + polycrystalline silicon layer and back passivation layer set gradually along the distancing the direction of N type silicon chip, its characterized in that, the N type contact passivation battery still includes intrinsic polycrystalline silicon layer and N + + heavily doped region, intrinsic polycrystalline silicon layer locate the N + polycrystalline silicon layer with between the back passivation layer, N + + heavily doped region runs through the intrinsic polycrystalline silicon layer, the inner in N + + heavily doped region with the contact of N + polycrystalline silicon layer, back metal electrode runs through the back passivation layer, the inner end of the back metal electrode is in contact with the outer end of the n + + heavily doped region, wherein the thickness of the n + polycrystalline silicon layer is 10-50nm, and the thickness of the intrinsic polycrystalline silicon layer is 50-250 nm.

2. The N-contact passivated cell of claim 1 wherein the dopant of the N + + heavily doped region is phosphorus.

3. The N-type contact passivated cell of claim 1 wherein the N + + heavily doped region is a N + + heavily doped region formed by a laser doping process.

4. The N-contact passivated cell of claim 1, wherein the tunneling layer is a deposited tunneling layer.

5. The N-contact passivated cell of claim 1 wherein the N + polysilicon layer is a deposited N + polysilicon layer.

6. The N-contact passivated cell of claim 1 wherein the intrinsic polysilicon layer is a deposited intrinsic polysilicon layer.

7. The N-type contact passivated cell of claim 1 wherein the front side structure comprises a p + doped layer, a front side passivated layer and a front side metal electrode, the p + doped layer and the front side passivated layer are sequentially disposed in a direction away from the N-type silicon wafer, the front side metal electrode penetrates through the front side passivated layer, and an inner end of the front side metal electrode is in contact with the p + doped layer.

8. The N-contact passivated cell of claim 7 wherein the dopant of the p + doped layer is boron tribromide.

9. The N-contact passivated cell of claim 7 wherein the p + doped layer is a p + doped layer formed by airborne dopant means.

10. The N-contact passivated cell of claim 7 wherein the front side passivation layer and the back side passivation layer are both antireflective passivation films.

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