CN114300573A - A method for optimizing the monitoring of backside overprint offset during the production of crystalline silicon solar cells - Google Patents

Abstract

The invention discloses a method for optimizing the monitoring of back overprinting offset during the manufacture of crystalline silicon solar cells, comprising the following steps: a. cell manufacturing, forming a detection pattern on the silicon wafer substrate of a PERC double-sided cell, that is, a back laser Graphics and overprinting of aluminum grid lines within the outline of the front layer pattern by screen printing; b. Screen printing overprint alignment detection, extending the laser line at the arc to the edge of the silicon wafer substrate, the aluminum The grid pattern overprints the back laser pattern, and the laser lines are exposed outside the aluminum grid pattern; by directly checking whether the laser lines extended from the four arc corners are aligned with the printed aluminum grid lines to monitor whether the overprinting is present or not offset. The method provided by the invention reduces the loss of aluminum paste caused by wiping, reduces the production cost, and also avoids the loss of cell efficiency and yield due to unclean wiping.

Description

A method for optimizing the monitoring of backside overprint offset during the production of crystalline silicon solar cells

technical field

The invention relates to the technical field of solar energy assistance, and relates to a method for optimizing the monitoring of back overprint offset during the manufacture of crystalline silicon solar cells.

Background technique

In recent years, due to the energy crisis and the increasingly serious environmental pollution, countries have gradually increased the production and investment of renewable energy, the entire industry chain has achieved breakthroughs and rapid development, and the cost of electricity is getting lower and lower. In some countries and regions, supply-side parity can be achieved. Low cost and high efficiency are the two magic weapons for reducing the cost of electricity per kilowatt hour. The PERC process has always become the standard for production expansion in the entire industry due to its rapid power increase and significant cost reduction.

The concept of PERC bifacial cells was introduced in 2015 and has been rapidly commercialized. The double-sided cell adopts an aluminum grid line structure instead of the all-aluminum layer structure of conventional PERC cells. While maintaining the high conversion efficiency of the front side, the back side can also generate electricity. The back aluminum gate line needs to be aligned with the laser grooved area, and an ohmic contact is formed with the silicon wafer through the laser grooved area to achieve the effect of collecting carriers. Because the characteristics of the aluminum paste determine that it cannot burn through the AlO _x and SiN _x :H films, if the aluminum grid lines are not printed in the laser grooved area, a better quality localized surface field (LBSF) and electrode contact cannot be formed. Cause the battery EL graphics to be black, affecting the battery efficiency.

At present, to monitor whether there is any offset in the printing, it is necessary to wipe off the printed aluminum grid lines, and then check under the microscope whether the aluminum grid lines are printed in the laser opening area. , you need to wipe the whole aluminum grid line clean and print again. This method requires employees to take the time to wipe and rework, which increases the workload of employees; wipes off the aluminum paste and reprints it, which increases the loss of aluminum paste; if the wipe is not clean, it will affect the cell efficiency and yield.

Therefore, there is an urgent need to develop a more convenient and labor-saving method for monitoring the backside overprint offset during the fabrication of crystalline silicon solar cells.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, the present invention provides a method for optimizing the monitoring of the backside overprint offset during the fabrication of crystalline silicon solar cells. In the present application, by expanding the laser opening area at the four corners beyond the aluminum grid line, it is possible to directly monitor the printing of the aluminum grid line for offset without wiping the aluminum grid line; and the output of the laser equipment is basically not affected.

The invention discloses a method for optimizing the monitoring of back overprinting offset during the manufacture of crystalline silicon solar cells, the method comprising the following steps:

a. The manufacture of the cell, using the laser process on the silicon wafer substrate of the PERC double-sided cell to break down the aluminum oxide + SiN _x :H dielectric film according to the back laser pattern, exposing the silicon wafer substrate, that is, the back laser opening, The aluminum grid lines are overprinted in the area of the back laser opening to achieve contact with the silicon wafer substrate, and after high temperature sintering, the battery is made;

b. Screen printing overprint alignment detection, the cell structure is a square with rounded corners, with four symmetrically arranged arc corners, and each corner has the same design; extend the laser line at the arc to the silicon wafer substrate The edge of the aluminum grid line pattern is overprinted with the back laser pattern, and the laser line is exposed outside the aluminum grid line pattern;

By directly checking whether the laser lines extended from the four arc corners are aligned with the printed aluminum grid lines to monitor whether the overprint is offset or not, if the laser lines are aligned with the aluminum grid lines, it is determined that there is no offset; If the laser line and the aluminum grid line are not aligned, it is determined that there is an offset.

As a further improvement of the embodiment of the present invention, a plurality of back laser patterns are provided as detection patterns.

As a further improvement of the embodiment of the present invention, the plurality of detection patterns are divided into at least one group, and the plurality of detection patterns in the same group are based on the outline of a section of aluminum grid lines of the previous layer pattern.

As a further improvement of the embodiment of the present invention, during the screen printing overprint alignment detection, the offset of the front electrode is determined according to the number of detection patterns with higher brightness.

The present invention has the following beneficial effects:

1. The method disclosed in the present invention does not require employees to take time to wipe for rework, reduces the workload of employees, and has more time for maintaining the normal production of the production line;

2. The method disclosed in the present invention reduces the loss of aluminum paste caused by wiping and reduces production costs;

3. The method disclosed in the present invention can avoid the loss of cell efficiency and yield due to unclean wiping.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are just some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a schematic diagram of the working principle of a method for optimizing backside overprint offset monitoring in the manufacture of a crystalline silicon solar cell according to an embodiment of the present invention.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The invention discloses a method for optimizing the monitoring of back overprinting offset during the manufacture of crystalline silicon solar cells, the method comprising the following steps:

a. The manufacture of the cell, using the laser process on the silicon wafer substrate of the PERC double-sided cell to break down the aluminum oxide + SiN _x :H dielectric film according to the back laser pattern, exposing the silicon wafer substrate, that is, the back laser opening, The aluminum grid lines are overprinted in the area of the back laser opening to achieve contact with the silicon wafer substrate, and after high temperature sintering, the battery is made;

b. Screen printing overprint alignment detection, the cell structure is a rounded square, with four symmetrically arranged arc corners, and the design of each corner is the same; the laser line at the arc is extended to the edge of the silicon wafer substrate, aluminum The grid pattern is overprinted with the back laser pattern, and the laser line is exposed outside the aluminum grid pattern;

By directly checking whether the laser lines extended from the four arc corners are aligned with the printed aluminum grid lines to monitor whether the overprint is offset or not, if the laser lines are aligned with the aluminum grid lines, it is determined that there is no offset; If the laser line and the aluminum grid line are not aligned, it is determined that there is an offset.

Specifically, as shown in FIG. 1 , the battery sheet is a square with rounded corners, and has the same four rounded corners. This example is one of the corners, and the design of each corner is the same. Picture a is an aluminum grid line pattern, b1 and c1 are the back laser pattern and the overprinted pattern in the prior art, and b2 and c2 are the backside laser pattern and the overprinted pattern involved in the application. Compared with b1, the laser line at the arc is extended to the edge of the silicon wafer substrate. The extension line has no effect on the output of the laser equipment. The aluminum grid line pattern is overprinted with the optimized back laser pattern, and there is a laser outside the aluminum grid line pattern. The lines are exposed; monitor whether the overprint is offset or not, you can directly check whether the laser lines extended from the four arc corners are aligned with the printed aluminum grid lines.

Further, in other optional embodiments, a plurality of detection patterns may be set, and the plurality of detection patterns are divided into at least one group, and the plurality of detection patterns in the same group are based on the outline of a section of aluminum grid line of the previous layer pattern. .

Preferably, the offset of the front electrode is determined according to the number of detection patterns with higher brightness during the screen printing overprint alignment detection.

The present invention has the following beneficial effects:

1. The method disclosed in the present invention does not require employees to take time to wipe for rework, reduces the workload of employees, and has more time for maintaining the normal production of the production line;

2. The method disclosed in the present invention reduces the loss of aluminum paste caused by wiping and reduces production costs;

3. The method disclosed in the present invention can avoid the loss of cell efficiency and yield due to unclean wiping.

Claims (4)

1. a method for backside overprint offset monitoring during the manufacture of an optimized crystalline silicon solar cell, is characterized in that, the method comprises the following steps: a. The manufacture of the cell, using the laser process on the silicon wafer substrate of the PERC double-sided cell to break down the aluminum oxide + SiN _x :H dielectric film according to the back laser pattern, exposing the silicon wafer substrate, that is, the back laser opening, The aluminum grid lines are overprinted in the area of the back laser opening to achieve contact with the silicon wafer substrate, and after high temperature sintering, the battery is made; b. Screen printing overprint alignment detection, the cell structure is a square with rounded corners, with four symmetrically arranged arc corners, and each corner has the same design; extend the laser line at the arc to the silicon wafer substrate The edge of the aluminum grid line pattern is overprinted with the back laser pattern, and the laser line is exposed outside the aluminum grid line pattern; By directly checking whether the laser lines extended from the four arc corners are aligned with the printed aluminum grid lines to monitor whether the overprint is offset or not, if the laser lines are aligned with the aluminum grid lines, it is determined that there is no offset; If the laser line and the aluminum grid line are not aligned, it is determined that there is an offset. 2 . The method for optimizing the monitoring of backside overprinting during the manufacture of crystalline silicon solar cells according to claim 1 , wherein a plurality of backside laser patterns are set as detection patterns. 3 . 3. The method for backside overprint offset monitoring when optimizing the production of crystalline silicon solar cells according to claim 2, wherein the plurality of detection patterns are divided into at least one group, and the plurality of detection patterns in the same group are the same as those of the previous layer pattern. The outline of a section of aluminum grid line is the benchmark. 4. The method for monitoring the offset of back overprinting during the production of optimized crystalline silicon solar cells according to claim 1, wherein, during the alignment detection of screen printing overprinting, the front electrode is judged according to the number of detection patterns with higher brightness offset.

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