CN107946409A - A kind of back side junction method of IBC solar cell - Google Patents

Abstract

The application discloses a back junction making method of an IBC solar cell, which comprises the following steps: after alkali texturing is carried out on a silicon wafer, patterned first electrode type doping and second electrode type doping are formed on the back surface of the silicon wafer, wherein the first electrode type doping and the second electrode type doping are opposite, and at least one of the first electrode type doping and the second electrode type doping adopts a laser doping mode. The back junction manufacturing method of the IBC solar cell can simplify the manufacturing process of the IBC solar cell while ensuring the manufacturing precision, save the material cost and the time cost for preparing the cell and avoid the damage of a matrix.

Description

A kind of back side junction method of IBC solar cell

technical field

The invention belongs to the technical field of photovoltaic equipment manufacturing, and in particular relates to a backside junction method of an IBC solar cell.

Background technique

N-type crystalline silicon solar cells avoid the B-O defect in P-type silicon and have a high minority carrier lifetime, and are often used in the development and manufacture of high-efficiency crystalline silicon solar cells. Due to the shielding of the front electrode of the traditional N-type battery, the incident light cannot be completely received by the battery to generate electricity, while the IBC (Interdigitated Back Contact, interdigitated back contact) battery has no metal grid on the front, which can increase the reflectance of light by 5-7 %, so the power generation effect with better efficiency can be obtained. U.S. solar cell manufacturer SunPower relies on its IBC cell technology to make its cells reach the highest efficiency of mass-produced crystalline silicon cells. Japan's Kaneka has combined IBC and HIT cell technologies to develop a high-efficiency solar cell with an efficiency of 26.7%. Solar battery.

The existing technology is to form diffusion openings through multi-step masks and slots, so that the dopant source thermally diffuses into the crystalline silicon substrate to form a certain pattern of back doping. By controlling the diffusion parameters, the ideal doping concentration and junction depth can be obtained. , but the multi-step masking and grooving increases the manufacturing cost, and the production efficiency is also greatly limited. It is also possible to form back doping in a certain pattern by ion implantation, but it will cause structural damage to the crystalline silicon substrate, resulting in surface amorphization or introduction of point defects. Therefore, a specific annealing process is often required to eliminate defects, and the process is relatively complicated.

Contents of the invention

In order to solve the above problems, the present invention provides a method for fabricating the back of an IBC solar cell, which can simplify the manufacturing process of the IBC cell while ensuring the manufacturing accuracy, save the material cost and time cost of preparing the cell, and avoid damage to the substrate .

A method for making a junction on the back of an IBC solar cell provided by the invention comprises:

After performing alkali texturing on the silicon wafer, patterned first electrode type doping and second electrode type doping are formed on the back of the silicon wafer, wherein the first electrode type is opposite to the second electrode type, At least one of the first electrode type doping and the second electrode type doping is laser doping.

Preferably, in the above-mentioned rear junction method of IBC solar cells, the formation of patterned first electrode type doping and second electrode type doping on the back side of the silicon wafer includes:

forming a mask on the back side of the silicon wafer and opening holes for boron diffusion;

removing the BSG and the mask;

A phosphorus source is deposited on the back side of the silicon wafer and laser doped to form a pattern.

Preferably, in the above-mentioned rear junction method of IBC solar cells, the formation of patterned first electrode type doping and second electrode type doping on the back side of the silicon wafer includes:

forming a mask on the back side of the silicon wafer and opening holes for phosphorous diffusion;

removing the PSG and the mask;

A boron source is deposited on the back of the silicon wafer and laser doped to form a pattern.

Preferably, in the above-mentioned rear junction method of IBC solar cells, the formation of patterned first electrode type doping and second electrode type doping on the back side of the silicon wafer includes:

Depositing a boron source on the back side of the silicon wafer and performing laser doping to form a first pattern;

Remove BSG;

Depositing a phosphorus source on the back side of the silicon wafer and performing laser doping to form a second pattern;

Remove PSG.

Preferably, in the above-mentioned method for fabricating back junctions of IBC solar cells, the laser doping method is as follows:

Use a laser with a wavelength of 532nm or 355nm, a power of 5W to 60W, a pulse width of 5ns to 200ns, a frequency of 20kHz to 100kHz, and a spot or stripe spot diameter of 5μm to 400μm to irradiate the back of the silicon wafer to form a depth range The heavily doped backside field region is 0.4μm to 2.4μm and the square resistance is 10Ohm/sq to 100Ohm/sq.

Preferably, in the back junction method of the above-mentioned IBC solar cell, the mask formed on the back side of the silicon wafer is:

A _SiO2 mask or a _SiOxNy mask or _SiNx mask with a thickness of 100nm to 300nm or a _SiOxNy mask or SiNxmask with a thickness of 100nm to 250nm is formed on the backside of the silicon wafer.

Preferably, in the method for making the backside of the above-mentioned IBC solar cell, the opening is:

Grooves with a width ranging from 120 μm to 1200 μm are etched on the mask with an interval of 150 μm to 1500 μm by using an etching laser.

Preferably, in the method for making the back of the above-mentioned IBC solar cell, the phosphorus source deposited on the back of the silicon wafer is:

A phosphorus source is deposited on the back side of the silicon wafer by means of APCVD or printing.

Preferably, in the method for making the backside of the above-mentioned IBC solar cell, the boron source deposited on the backside of the silicon wafer is:

A boron source is deposited on the back of the silicon wafer by means of APCVD or printing.

Preferably, in the above-mentioned rear junction method of IBC solar cells, after forming the patterned first electrode type doping and second electrode type doping on the back side of the silicon wafer, it further includes:

Deposit 10nm to 120nm AlO _x passivation layer by ALD or thermal oxidation to form 10nm to 120nm SiO _x passivation layer, and deposit 20nm to 150nm SiN _x anti-reflection layer by PECVD;

Metallization is performed to form contacts.

It can be seen from the above description that the method for fabricating the backside of the above-mentioned IBC solar cell provided by the present invention is to form a patterned first electrode type doping and a second electrode on the backside of the silicon wafer after alkali texturing of the silicon wafer. type doping, wherein the first electrode type is opposite to the second electrode type, and at least one of the first electrode type doping and the second electrode type doping is laser doping, Therefore, while ensuring the manufacturing accuracy, the manufacturing process of the IBC battery can be simplified, the material cost and time cost of preparing the battery can be saved, and the matrix can be avoided from being damaged.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

FIG. 1 is a schematic diagram of a first method for fabricating a back junction of an IBC solar cell provided in an embodiment of the present application.

Detailed ways

The core idea of the present invention is to provide a method for fabricating the backside of an IBC solar cell, which can simplify the manufacturing process of the IBC cell while ensuring the manufacturing accuracy, save the cost of materials and time for preparing the cell, and avoid damage to the substrate.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The backside junction method of the first IBC solar cell provided in the embodiment of the present application is shown in Figure 1, and Figure 1 is a schematic diagram of the backside junction method of the first IBC solar cell provided in the embodiment of the application, the method includes the following step:

S1: Alkali texturing of silicon wafers;

A silicon wafer with a thickness of 120nm to 280um can be selected as the N-type silicon substrate, and a pyramid structure is formed on the surface of the silicon wafer by alkali texturing.

S2: Forming patterned first electrode type doping and second electrode type doping on the back surface of the silicon wafer, wherein the first electrode type and the second electrode type are opposite, and the first electrode type doping At least one of doping and doping of the second electrode type is laser doping.

It should be noted that when the doping of the first electrode type is N-type doping, the doping of the second electrode type is P-type doping, and when the doping of the first electrode type is P-type doping , the second electrode type doping is N-type doping. In this case, laser doping can be used for N-type doping, and laser doping can also be used for P-type doping. , In addition, laser doping can also be used simultaneously in the two processes of N-type doping and P-type doping. The emitter or BSF is formed by laser doping, which can avoid further mask opening and diffusion process, and the doping region with a certain doping pattern can be formed through the control system, which simplifies the manufacturing process of the IBC battery and greatly The material cost and time cost for preparing the battery are saved.

It can be known from the above description that in the first method for backside junction of IBC solar cells provided by the embodiment of the present application, after the silicon wafer is subjected to alkali texturing, a patterned first electrode type doping is formed on the back side of the silicon wafer. Doping with the second electrode type, wherein the first electrode type is opposite to the second electrode type, and at least one of the first electrode type doping and the second electrode type doping is laser doped Therefore, while ensuring the manufacturing accuracy, the manufacturing process of the IBC battery can be simplified, the material cost and time cost of preparing the battery can be saved, and the matrix can be avoided from being damaged.

The second method for fabricating the backside of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned first method for fabricating the backside of an IBC solar cell, and further includes the following technical features:

The patterned doping of the first electrode type and the doping of the second electrode type on the back side of the silicon wafer includes:

forming a mask on the back side of the silicon wafer and opening holes for boron diffusion;

removing the BSG and the mask;

A phosphorus source is deposited on the back side of the silicon wafer and laser doped to form a pattern.

It should be noted that this embodiment is a laser doping method only used in the N-type doping process, which simplifies the manufacturing process of the IBC battery and greatly saves the cost of materials and time for preparing the battery.

The third method for fabricating the backside of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned first method for fabricating the backside of an IBC solar cell, and further includes the following technical features:

The patterned doping of the first electrode type and the doping of the second electrode type on the back side of the silicon wafer includes:

forming a mask on the back side of the silicon wafer and opening holes for phosphorous diffusion;

removing the PSG and the mask;

A boron source is deposited on the back of the silicon wafer and laser doped to form a pattern.

It should be noted that this embodiment is a laser doping method only used in the P-type doping process, which simplifies the manufacturing process of the IBC battery and greatly saves the cost of materials and time for preparing the battery.

The fourth method for fabricating the backside of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned first method for fabricating the backside of an IBC solar cell, and further includes the following technical features:

The patterned doping of the first electrode type and the doping of the second electrode type on the back side of the silicon wafer includes:

Depositing a boron source on the back side of the silicon wafer and performing laser doping to form a first pattern;

Remove BSG;

Depositing a phosphorus source on the back side of the silicon wafer and performing laser doping to form a second pattern;

Remove PSG.

It should be noted that this embodiment is a laser doping method used in the process of N-type doping and P-type doping at the same time, which simplifies the manufacturing process of the IBC battery and greatly saves the material cost and time cost of preparing the battery. , and may, but is not limited to, utilize hydrofluoric acid to remove the PSG.

The fifth method for fabricating the back of an IBC solar cell provided in the embodiment of the present application is based on any one of the above-mentioned first to fourth methods for fabricating the back of an IBC solar cell, and further includes the following technical features:

The laser doping method is:

Use a laser with a wavelength of 532nm or 355nm, a power of 5W to 60W, a pulse width of 5ns to 200ns, a frequency of 20kHz to 100kHz, and a spot or stripe spot diameter of 5μm to 400μm to irradiate the back of the silicon wafer to form a depth range The heavily doped backside field region is 0.4μm to 2.4μm and the square resistance is 10Ohm/sq to 100Ohm/sq.

The parameters of this laser are the optimal solution obtained through many experiments, which can achieve sufficient depth of doping.

The sixth method for fabricating the backside of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned second or third method for fabricating the backside of an IBC solar cell, and further includes the following technical features:

The mask formed on the back side of the silicon wafer is:

A _SiO2 mask or a _SiOxNy mask or _SiNx mask with a thickness of 100nm to 300nm or a _SiOxNy mask or SiNxmask with a thickness of 100nm to 250nm is formed on the backside of the silicon wafer.

It should be noted that the SiO ₂ mask is obtained by thermal oxidation in a diffusion furnace, and the SiO _x N _y mask and SiN _x mask can be obtained by PECVD. This thickness and type of mask can effectively Protection during diffusion.

The seventh method for fabricating the backside of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned sixth method for fabricating the backside of an IBC solar cell, and further includes the following technical features:

The openings are:

Grooves with a width ranging from 120 μm to 1200 μm are etched on the mask with an interval of 150 μm to 1500 μm by using an etching laser.

After opening such a trench, perform boron diffusion in a diffusion furnace to form an emitter with a junction depth of 0.6μm to 1.2μm and a square resistance of 16Ohm/sq to 300Ohm/sq, and then use hydrofluoric acid to remove the mask and BSG.

The eighth method for fabricating the back of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned second or fourth method for fabricating the back of an IBC solar cell, and further includes the following technical features:

The phosphorus source deposited on the back side of the silicon wafer is:

A phosphorus source is deposited on the back side of the silicon wafer by means of APCVD or printing.

It should be noted that the phosphorus source mentioned here may be PSG or other semiconductor materials containing phosphorus, which is not limited here.

The ninth method for fabricating the back of an IBC solar cell provided in the embodiment of the present application is based on the above-mentioned third or fourth method for fabricating the back of an IBC solar cell, and further includes the following technical features:

The boron source deposited on the back side of the silicon wafer is:

A boron source is deposited on the back of the silicon wafer by means of APCVD or printing.

The tenth method for fabricating the back of an IBC solar cell provided in the embodiment of the present application is based on any one of the above-mentioned first to fourth methods for fabricating the back of an IBC solar cell, and further includes the following technical features:

After forming the patterned doping of the first electrode type and the doping of the second electrode type on the back side of the silicon wafer, it also includes:

Deposit 10nm to 120nm AlO _x passivation layer by ALD or thermal oxidation to form 10nm to 120nm SiO _x passivation layer, and deposit 20nm to 150nm SiN _x anti-reflection layer by PECVD;

Metallization is performed to form contacts.

It should be noted that the thermal oxidation process is carried out in a diffusion furnace, and after these two steps, a complete IBC solar cell is formed.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not 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. a kind of back side knot method of IBC solar cells, it is characterised in that including：

After carrying out alkali making herbs into wool to silicon chip, patterned first electrode type doping and the second electricity are formed at the back side of the silicon chip The doping of pole type, wherein the first electrode type and the second electrode type on the contrary, first electrode type doping and At least one of second electrode type doping using laser doping mode.

2. the back side knot method of IBC solar cells according to claim 1, it is characterised in that described in the silicon The back side of piece, which forms the patterned doping of first electrode type and the doping of second electrode type, to be included：

Mask is formed at the back side of the silicon chip and perforate carries out boron diffusion；

Remove BSG and the mask；

The silicon chip backside deposition phosphorus source and carry out laser doping formed figure.

3. the back side knot method of IBC solar cells according to claim 1, it is characterised in that

It is described the doping of patterned first electrode type and the doping of second electrode type are formed at the back side of the silicon chip to include：

Mask is formed at the back side of the silicon chip and perforate carries out phosphorus diffusion；

Remove PSG and the mask；

The silicon chip backside deposition boron source and carry out laser doping formed figure.

4. the back side knot method of IBC solar cells according to claim 1, it is characterised in that described in the silicon The back side of piece, which forms the patterned doping of first electrode type and the doping of second electrode type, to be included：

The silicon chip backside deposition boron source and carry out laser doping formed the first figure；

Remove BSG；

The silicon chip backside deposition phosphorus source and carry out laser doping formed second graph；

Remove PSG.

5. according to the back side knot method of claim 1-4 any one of them IBC solar cells, it is characterised in that described The mode of laser doping is：

Using wavelength be 532nm or 355nm, power are 5W to 60W, pulse width is 5ns to 200ns, frequency be 20kHz extremely 100kHz, point-like or strip spot diameter are that 5 μm to 400 μm of laser irradiates the back side of the silicon chip, and forming depth bounds is 0.4 μm to 2.4 μm, the heavy doping back side field areas that sheet resistance is 10Ohm/sq to 100Ohm/sq.

6. the back side knot method of the IBC solar cells according to Claims 2 or 3, it is characterised in that described described The back side of silicon chip forms mask：

The SiO that thickness is 50nm to 300nm is formed at the back side of the silicon chip₂The SiO of mask or 50nm to 250nm_xN_yMask or SiN_xMask.

7. the back side knot method of IBC solar cells according to claim 6, it is characterised in that the perforate is：

Width range is etched as 120 μm to 1200 μ using 150 μm to 1500 μm of interval using laser is etched on the mask The groove of m.

8. the back side knot method of the IBC solar cells according to claim 2 or 4, it is characterised in that described described The backside deposition phosphorus source of silicon chip is：

In the backside deposition phosphorus source of the silicon chip in a manner of APCVD or printing.

9. the back side knot method of the IBC solar cells according to claim 3 or 4, it is characterised in that described described The backside deposition boron source of silicon chip is：

In the backside deposition boron source of the silicon chip in a manner of APCVD or printing.

10. according to the back side knot method of claim 1-4 any one of them IBC solar cells, it is characterised in that described Formed after the patterned doping of first electrode type and the doping of second electrode type, further included at the back side of the silicon chip：

The AlO of 10nm to 120nm is deposited in a manner of ALD_xPassivation layer or thermal oxide form the SiO of 10nm to 120nm_xPassivation layer, and The SiN of 20nm to 150nm is deposited in a manner of PECVD_xAntireflection layer；

Carry out metallization and form contact.