CN100551602C - Method and device at the silicon photocell surface groove - Google Patents

Abstract

The invention discloses processing method and device that cutting is carried out on a kind of surface at silicon photocell.This method adopt two bundle laser respectively with the normal direction symmetry angle of inclination+θ of processing plane and-θ, and the plane that makes two bundle laser places is perpendicular to line of rabbet joint direction, with condenser lens two bundle laser are focused on perpendicular on the line of rabbet joint direction, focus is positioned at the silicon chip surface below, along the translation of line of rabbet joint direction, two bundle Laser Processings form low wide and up narrow wire casing with processing plane.This device comprises laser instrument, light-splitting device, completely reflecting mirror, condenser lens, bidimensional precision stage.The present invention has advantages such as cutting processing tasks, the cost that can directly finish silicon photocell are low, efficient is high, the easy assurance of crudy.

Description

Method and device at the silicon photocell surface groove

Technical field

The present invention relates to a kind of processing method and device of silicon photocell, particularly relate to processing method and device that cutting is carried out on a kind of surface at silicon photocell.

Background technology

The solar photovoltaic generation system movement-less part, reliable, the few maintenance, life-span is long, and electric energy easily utilizes, easily carry, easily store, and photovoltaic generation is most active field during solar energy utilizes, it causes the concern of countries in the world, becomes the focus of each developed country's research and development.University of New South Wales has developed efficient and has reached 20% solar module, and the U.S., Japan, Germany and Britain etc. have all set up the pilot production line of this battery, and its battery efficiency reaches 17%-18%, and production scale enlarges rapidly.

The existing solar cell development of China is compared very big gap in addition with the level of production with international most advanced level, seek new technology, new material, new technology, to improve the solar cell conversion efficiency, reduce production costs significantly, be the urgent task that China photovoltaic interface is faced.

In order to reach purpose efficiently, silicon photocell can adopt the grooving and grid burying electrode structure.Grooving and grid burying electrode single crystal silicon solar cell is because of the unique texture of its buried gate electrode, make the electrode shaded area drop to 2-4% by the 10-15% of conventional batteries, short circuit current can rise 12%, with adopting heavily diffusion in the time slot, the area at metal-silicon interface is increased, contact resistance reduces, thereby makes fill factor, curve factor improve 10%; In battery is made, the characteristics that both kept high-efficiency battery, saved again efficient single crystal battery make in technology such as photoetching, make the grooving and grid burying electrode battery aspect maintenance high conversion efficiency and suitable large-scale production, become the tie that connects between efficient single crystal silicon solar cell in laboratory and the conventional batteries production.

Usually the main application of silicon photocell surface groove is used for embedding of silicon photocell surface electrode grid line, and with reference to shown in Figure 1, the line of rabbet joint is a strip, and its horizontal interface is a trapezoidal shape, and main technical requirements is as follows:

D represents the degree of depth: 30 μ m～60 μ m;

L1 represents on the horizontal interface of flute profile groove wide: 10 μ m～20 μ m;

L2 represents under the horizontal interface of flute profile groove wide:＞L1+2 μ m;

Existing processing method comprises both at home and abroad at present:

1) machining; Adopt diamond cutter, delineate successively with three kinds of cuttves and mold the groove of groove width greater than 10 μ m.The advantage of this method is: the properties of product quality that processes is good.But shortcoming is: the cost height, the equipment that present China carries out this type of processing must rely on import.

2) directly deposit; Adopt chemical method directly to go out electrode wires at the photocell surface deposition, the advantage of this method is: processing is simple, cost is low.But shortcoming is: the properties of product that process are of poor quality, and working (machining) efficiency is low, and product is short service life.

3) conventional laser cutting; With chemical method bottom land is widened again after carving wire casing with beam of laser.This method is at present still in the experimental stage, and effect is not determined yet, and the method difficulty is bigger, and cost is higher.

Because the above-mentioned deficiency of prior art just needs a kind of novel silicon photocell surface groove method and device.

Summary of the invention

The purpose of this invention is to provide a kind of good processability, lower, the simple silicon photocell surface groove method of operation enforcement of cost.

For achieving the above object, the technical solution used in the present invention is as follows:

Method at the silicon photocell surface groove may further comprise the steps:

1) laser instrument is set, on the light path of described laser instrument output laser a light-splitting device is set; Described laser instrument sends the laser that power is above 1064nm wavelength of 50W or the above 355nm wavelength of power 20W;

2) with described light-splitting device laser beam homenergic ground is divided into two bundle laser;

3) with two bundle laser respectively with the normal direction of processing plane symmetry angle of inclination+θ and-θ; And the plane that makes two bundle laser places is perpendicular to line of rabbet joint direction, as shown in Figure 2;

4) with condenser lens two bundle laser are focused on perpendicular on the line of rabbet joint direction; It is the d place that focus is positioned at the silicon chip 6 lower face degree of depth, and the span of d is 30 μ m～60 μ m;

5) with processing plane along the translation of line of rabbet joint direction, two the bundle Laser Processings forms low wide and up narrow wire casing.

In technique scheme, the beam quality factor M of laser in the step 1) ²＜3;

In technique scheme, in the step 3), 0 °≤θ≤60 °.

At the device of silicon photocell surface groove, as shown in Figure 3, comprising:

One laser instrument 1;

One light-splitting device 2, be placed on the light-emitting window of described laser instrument 1 by support before;

One completely reflecting mirror 3 is placed on by support on a branch of beam split light path of described light-splitting device 2;

One condenser lens 4 is placed on by support on another bundle beam split light path of described light-splitting device 2, and the reverberation of described completely reflecting mirror 3 is also by this condenser lens 4 simultaneously;

One bidimensional precision stage 5 is placed on after the described condenser lens 4; One silicon chip 6 to be processed is fixed on this bidimensional precision stage 5, and the plane at two bundle transmitted light places of described condenser lens 4 is vertical with these silicon chip 6 finished surfaces.

In technique scheme, described laser instrument 1 is the laser instrument of the 532nm of 30W-40W for the above 1064nm wavelength of power 50W or with power, or the ultraviolet laser of power 10W-20W, and repetition rate is greater than 4K Hz, the beam quality factor M of laser ²＜3;

In technique scheme, two bundle transmitted lights of described condenser lens 4 respectively and the angle theta between the silicon chip 6 finished surface normal directions about this normal symmetry, angular range is 0 °≤θ≤60 °.

The present invention is applicable to the cutting on silicon materials photocell surface.

Compared with prior art, the invention has the beneficial effects as follows:

1) directly finishes the cutting processing tasks of silicon photocell;

2) cost is low;

3) efficient height;

4) crudy guarantees easily.

Description of drawings

Fig. 1 (a) expression silicon photocell surface wire casing front elevational schematic;

Fig. 1 (b) expression silicon photocell surface wire casing cross sectional representation;

Fig. 2 represents the angle schematic diagram between laser beam and the silicon photocell surface normal;

Fig. 3 represents the device schematic diagram of the embodiment of the invention.

The specific embodiment

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

The method at the silicon photocell surface groove that present embodiment provides may further comprise the steps:

1) provide beam of laser, laser parameter is as follows:

Maximum continuous laser power is 55W;

The peak-peak laser power is 75KW;

Optical maser wavelength is 1064nm;

Beam quality factor M ²=2.8;

Repetition rate is 1KHz;

2) with light-splitting device laser beam homenergic ground is divided into two bundle laser; This light-splitting device adopts 50% spectroscope;

3) with two bundle laser respectively with the normal direction of processing plane symmetry angle of inclination+20 ° and-20 °; And the plane that makes two bundle laser places is perpendicular to line of rabbet joint direction, as shown in Figure 2; Wherein beam of laser directly is incident on the finished surface, and another Shu Jiguang incides finished surface after reflecting by a completely reflecting mirror;

4) be that the 10cm condenser lens focuses on two bundle laser perpendicular on the line of rabbet joint direction with focal length; Focus is positioned at silicon chip surface below 30 μ m;

5) with processing plane along the translation of line of rabbet joint direction, two bundle Laser Processings forming d=30 μ m, L1=10 μ m; The wire casing of L2=12 μ m.

The device at the silicon photocell surface groove that present embodiment provides as shown in Figure 3, comprising:

One laser instrument 1; One light-splitting device 2, be placed on the light-emitting window of described laser instrument 1 by support before; One completely reflecting mirror 3 is placed on by support on a branch of beam split light path of described light-splitting device 2; One condenser lens 4 is placed on by support on another bundle beam split light path of described light-splitting device 2, and the reverberation of described completely reflecting mirror 3 is also by this condenser lens 4 simultaneously; One bidimensional precision stage 5 is placed on after the described condenser lens 4; One silicon chip 6 to be processed is fixed on this bidimensional precision stage 5, and the plane at two bundle transmitted light places of described condenser lens 4 is vertical with these silicon chip 6 finished surfaces.

Below the device various piece is elaborated.

Laser instrument 1 adopts all solid state acousto-optic Q modulation laser of semiconductor pumped YAG, and its key technical indexes is:

Maximum continuous laser power 55W;

Peak-peak laser power 75KW;

Optical maser wavelength 1064nm;

Beam quality factor M ²=2.8;

Repetition rate 1KHz;

Light-splitting device 2 adopts a T=50% half-reflecting mirror and a completely reflecting mirror that laser is divided into two bundles and is adjusted to 50 ° of certain angle angles.This angle can require to determine that in general, angle increases according to cutting, and groove depth reduces, and the cutting width strengthens; Angle reduces, and groove depth deepens, and the cutting width reduces.When angle is increased to a certain degree, will produce boss in the middle of the groove at quarter, and the height of boss increases with the increase of angle.For carving the constant groove of specification, angle is constant in the delineation process.

Completely reflecting mirror 3, the conventional completely reflecting mirror of employing respective wavelength.

Condenser lens 4 adopt the amasthenic lens of the about 50mm of a diameter, focal length 70mm that two-beam is converged on the same focal plane, and the bifocal line should be perpendicular with the groove longitudinal direction.Will take into account clear aperture to the selection of amasthenic lens diameter goes to consider to the influence of focusing effect and the complexity of short focal length anaberration lens design of heavy caliber and processing; The amasthenic lens of short focal length can realize that littler focal beam spot to realize higher focus power density, splashes amasthenic lens but focal length collapses the residue that spatters when too weak point can make laser grooving.In the present embodiment, carve d=30 μ m, L1=10 μ m; The cutting of L2=12 μ m makes the angle of the two bundle laser that incide the silicon finished surface equal 40 °.

Bidimensional precision stage 5 adopts X=200mm, the bidimensional precision stage of Y=200mm.It is X=200mm that silicon photoelectric cell slice is placed on stroke, on the bidimensional precision stage of Y=200mm, utilize the action of industrial computer control workbench and the bright dipping and the disconnected light of laser, utilize the high power density at focus place to make the gasification of battery sheet surface, thereby realize the high speed cutting of battery sheet.

Because laser beam intersects, if desired the trench bottom of Keing at the bottom width of groove than wide more in top, and groove depth relatively before the time, convex of groove central authorities meeting formation, the height of boss increases with the increase of angle.The generation of boss can make trench bottom become uneven, and this has no relations, usually the main application of silicon photocell surface groove, be used for embedding of silicon photocell surface electrode grid line, boss has been arranged, increased the contact area and the degree of irregularity that need embed grid, can prevent better that electrode from dropping out.

Claims (4)

1, in the method for silicon photocell surface groove, may further comprise the steps:

1) laser instrument is set, on the light path of described laser instrument output laser a light-splitting device is set;

2) with described light-splitting device laser beam homenergic ground is divided into two bundle laser;

3) with two bundle laser respectively with the normal direction of processing plane symmetry angle of inclination+θ and-θ; And the plane that makes two bundle laser places is perpendicular to line of rabbet joint direction;

4) two bundle laser are focused on perpendicular on the line of rabbet joint direction, focus is positioned at the silicon chip surface below;

5) with processing plane along the translation of line of rabbet joint direction, two the bundle Laser Processings forms low wide and up narrow wire casing.

2, the method at the silicon photocell surface groove according to claim 1 is characterized in that, the laser output power in the described step 1) is the laser of above 1064nm wavelength of 50W or the above 355nm wavelength of power 20W, beam quality factor M ²＜3.

3, the method at the silicon photocell surface groove according to claim 1 is characterized in that, to be positioned at the silicon chip surface below degree of depth be the d place to focus in the described step 4), and the span of d is 30 μ m～60 μ m.

4, the method at the silicon photocell surface groove according to claim 1 is characterized in that, in the described step 3), and 0 °＜θ≤60 °.

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