CN112071925A - Novel crystalline silicon battery structure and preparation process thereof - Google Patents

Abstract

The present invention relates to the field of solar cell production. A new type of crystalline silicon cell structure, the upper surface of the crystalline silicon cell is composed of a staggered groove texture surface and a laser-doped region. The invention also relates to the preparation process of the novel crystalline silicon battery structure. The invention is not only conducive to the formation of a good ohmic contact, but also has extremely low reflectivity in the non-metallized area, the surface reflectivity of the silicon wafer is reduced to 3-5%, and the photon absorption rate is increased. The process is simple, the equipment compatibility is strong, and the battery conversion efficiency is increased by 0.3-0.5%.

Description

A new type of crystalline silicon battery structure and its preparation process

technical field

The present invention relates to the field of solar cell production.

Background technique

The improvement of the conversion efficiency of crystalline silicon cells can improve the electrical gain on the one hand, and increase the optical gain on the other hand. Currently, single-crystalline PERC cells use grooved alkali to make texturing, and form a pyramid light trapping structure on the surface of the silicon wafer, with a reflectivity of 8 -13%. Based on current texturing technology, there is little possibility of further reducing reflectivity or increasing photon utilization.

SUMMARY OF THE INVENTION

The purpose of the present invention is to reduce the reflectivity of the silicon wafer surface to 3-5% by preparing the staggered surface of the trench texture surface and the laser-doped region, and to ensure the passivation effect of the surface at the trench.

The technical scheme adopted in the present invention is: a novel crystalline silicon battery structure, the upper surface of the crystalline silicon battery is composed of a staggered groove texture surface and a laser doped region.

The groove interval on the grooved suede is 1.42-1.48mm, and the groove width is 0.03mm. The suede between the grooves is divided into six pieces longitudinally, the width of the middle four pieces is 30.5mm, and each piece on the left and right sides is divided into six pieces. The width is 14.75-16.75mm, and the interval between adjacent blocks is 0.7mm.

Each textured surface between the grooves has a lateral width of 5 μm and a number of 46-58 equally spaced laser-doped regions of metal lines.

A new type of crystalline silicon battery structure surface preparation process, the following steps are carried out

Step 1, mask layer preparation;

Step 2, the engraving of groove pattern;

Step 3, texturing;

Step 4: Diffusion knotting;

Step 5, laser doping;

Step 6, back PSG and back etching;

Step seven, high temperature oxidation;

Step 8, front anti-reflection film;

Step 9, back passivation and anti-reflection film;

Step 10. Laser grooving on the back;

Step eleven, screen printing.

In step 1, adopt the thermal diffusion process, first pass N2 at a flow rate of 10slm, raise the temperature to 780 °C, and wait for 5min; The temperature is 780°C, the deposition time is 3-5min, the PSG film thickness is 50-100nm, and the doping concentration is 3*10 ²¹ -5*10 ²¹ /cm ^-3 ; the ratio of N2 and POCl3 is the same as the prior art.

In step 2, a green laser source with a wavelength of 532nm is used, the laser spot size is 25-30um, the power is 40W, the modulation frequency is 200-240Khz, the engraving speed is 27000mm/min, and the groove interval on the groove engraving pattern is 1.42-1.48mm, The width of the groove is 0.03mm, the surface between the grooves is longitudinally divided into six pieces, the width of the four middle pieces is 30.5mm, the width of each piece on the left and right sides is 14.75-16.75mm, and the interval between adjacent pieces is 0.7mm , and each surface between the grooves has 46-58 equally spaced laser grooves with a width of 5 μm in the lateral direction.

In step 3, a grooved suede surface is formed by using a trough alkali texturing machine, and the thinning amount of each piece is 0.1-0.2g to prepare a 1-3 μm pyramid suede surface with a reflectivity of 3-5%, and the front surface is removed by a pickling tank. PSG.

The beneficial effects of the present invention are as follows: the present invention provides a novel crystalline silicon cell structure and a preparation process for trench texture, which can not only reduce the surface reflectivity of silicon wafers to 3-5%, but also have low ohmic contact resistance. The process is simple, the equipment compatibility is strong, and the battery conversion efficiency is increased by 0.3-0.5%.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the structural representation of groove suede;

Fig. 3 is the structural representation of monolithic suede;

Among them, 1, groove texture, 2, laser doping area, 3, middle block, 4, block spacing, 5, right block, 6, metal line laser doping.

Detailed ways

As shown in FIG. 1 , the present invention proposes a preparation process of a novel crystalline silicon cell trench texture, and the front surface geometric structure is composed of a trench texture 1 and a laser-doped region 2 interlaced. The specific preparation process of the battery structure is as follows:

1. Mask layer preparation. Using the thermal diffusion process, first pass N2 at a flow rate of 10slm, raise the temperature to 780 ℃, and wait for 5 minutes; then feed 300-500 sccm of N2, 900-1500 sccm of N2-POCl3, 800-1200 sccm of O2, and the temperature is 780 ℃ , the deposition time is 3-5min, the PSG film thickness is 50-100nm, and the doping concentration is 3*10 ²¹ -5*10 ²¹ /cm ^-3 ;

2. Engraving of groove patterns. Using a green laser source with a wavelength of 532nm, the laser spot size is 25-30um, the power is 40W, the modulation frequency is 200-240Khz, and the engraving speed is 27000mm/min. As shown in Figure 1, the groove engraving pattern is composed of patterns 1 arranged horizontally at intervals 2, wherein the width of pattern 1 is 1.42-1.48mm, and the width of interval 2 is 0.03mm; Six blocks, in which the middle four blocks, each block 3 is 30.5mm wide, the two two blocks on both sides are 14.75-16.75mm wide, and the interval between each block is 0.7mm; as shown in Figure 3, the pattern 1 is composed of straight segments 6 arranged laterally at an interval of 5 μm, and the number is 46-58.

3. Texturing process. Use a groove alkali texturing machine to form a grooved textured surface with a thinning amount of 0.1-0.2g, prepare a 1-3 μm pyramid textured surface with a reflectivity of 3-5%, and use a pickling tank to remove the front PSG.

4. Diffusion knot.

5. Laser doping.

6. Back PSG and back etching. The back PSG was removed by a chain-type PSG removal device. The concentration of the stock solution was 49% HF, and the mixed solution of 1% volume concentration was configured with H2O. The reaction time was 0.5-2min. -0.2g, back reflectivity 30-45%.

7. High temperature oxidation.

8. Front anti-reflection film.

9. Back passivation and anti-reflection film.

10. Laser grooving on the back.

11. Screen printing.

All the content not described in the present invention adopts the technology and formula of the prior art.

Claims (7)

1. A novel crystalline silicon battery structure is characterized in that: the upper surface of the crystalline silicon battery is composed of a groove suede and a laser doping area in a staggered mode.

2. The novel crystalline silicon cell structure of claim 1, wherein: the interval between the grooves on the pile surface of the grooves is 1.42-1.48mm, the width of the grooves is 0.03mm, the pile surface between the grooves is longitudinally divided into six blocks, the width of the middle four blocks is 30.5mm, the width of each block on the left side and the right side is 14.75-16.75mm, and the interval between the adjacent blocks is 0.7 mm.

3. The novel crystalline silicon cell structure of claim 2, wherein: each suede between the grooves is provided with metal wire laser doping areas which are 5 mu m in transverse width and are equally spaced, 46-58.

4. The novel crystalline silicon cell structure surface preparation process of claim 1, characterized in that: the following steps are carried out

Step one, preparing a mask layer;

step two, carving the groove pattern;

step three, making wool;

step four, diffusion and junction making;

step five, laser doping;

sixthly, carrying out PSG and back etching;

seventhly, high-temperature oxidation;

step eight, a front antireflection film;

step nine, back passivation and antireflection coating;

step ten, back laser grooving;

and step eleven, screen printing.

5. The novel crystalline silicon cell structural surface preparation process as claimed in claim 4, characterized in that: in the first step, a thermal diffusion process is adopted,firstly, introducing N2 at the flow rate of 10slm, heating to 780 ℃, and waiting for 5 min; then respectively introducing N2 with the concentration of 300 plus 500sccm, N2-POCl3 with the concentration of 900 plus 1500sccm and O2 with the concentration of 800 plus 1200sccm, wherein the temperature is 780 ℃, the deposition time is 3-5min, the film thickness of PSG is 50-100nm, and the doping concentration is 3 x 10²¹-5*10²¹/cm^-3(ii) a The proportions of N2 and POCl3 were the same as in the prior art.

6. The novel crystalline silicon cell structural surface preparation process as claimed in claim 4, characterized in that: in the second step, a green laser source with 532nm wavelength is adopted, the size of a laser spot is 25-30um, the power is 40W, the modulation frequency is 200-240Khz, the engraving speed is 27000mm/min, the interval between grooves on the groove engraving pattern is 1.42-1.48mm, the width of the groove is 0.03mm, the surface between the grooves is longitudinally divided into six blocks, the width of the middle four blocks is 30.5mm, the width of each block on the left side and the right side is 14.75-16.75mm, the interval between adjacent blocks is 0.7mm, and each surface between the grooves is provided with 46-58 equally-spaced laser grooves with the transverse width of 5 mu m.

7. The novel crystalline silicon cell structural surface preparation process as claimed in claim 4, characterized in that: in the third step, a groove type alkali texturing machine is used for forming groove textured surfaces, the thinning amount of each piece is 0.1-0.2g, pyramid textured surfaces with the thickness of 1-3 mu m are prepared, the reflectivity is 3-5%, and a pickling tank is used for removing PSG on the front surface.

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