Background technology
In solar cell manufacturing process, diffusion square is a very important parameter, square, i.e. square resistance.Consider a block length be l, wide be a, the thick thin layer for t, if the resistivity of this layer material is ρ, then the resistance of this whole thin layer is
and in a certain proportion of nitric acid of silicon chip back side, hydrofluoric acid and sulfuric acid mixture liquid process to remove the effect of silicon chip back side and side phosphorus, remove phosphorosilicate glass simultaneously.
The making of solar battery sheet comprises the techniques such as chemical cleaning and surface-texturing process → diffusion → periphery etching and dephosphorization silex glass → depositing antireflection film → print electrode → sinter successively, and the concrete effect of each technique is as follows:
Chemical cleaning and surface-texturing process, namely make the silicon chip surface of light originally form scraggly structure, to increase the absorption of light by chemical reaction;
Diffusion, that is, by after spreading P-type silicon sheet, surface becomes N-type, forms PN junction, makes silicon chip have photovoltaic effect;
Periphery etching and dephosphorization silex glass, stay when the object of this technique is to remove diffusion that silicon chip edge formed by the conductive layer of PN junction two terminal shortcircuit, then cross HF groove, remove the phosphorosilicate glass formed in diffusion technology;
Depositing antireflection film, mainly contain and comprise two class antireflective coatings, be i.e. silicon nitride film and oxidation titanium film, Main Function is passivation and antireflective;
Print electrode, comprise front electrode printing, backplate printing and the printing of back of the body electric field;
Sintering, that is, make the process forming alloy between the electrode of printing and silicon chip.
In the manufacturing process of above-mentioned solar battery sheet, diffusion is core process when making solar battery sheet, because this technique forms PN junction, the efficiency of size to whole solar battery sheet of inspection diffusion square serves vital effect, therefore, if it is defective to record diffusion square after diffusion, then to the important step also becoming and improve whole efficiency of doing over again of defective diffusion square.
Current diffusion technology mostly adopts and spreads back-to-back, but the back side (should not carry out the one side spread) also can spread some phosphorus, and spreads that square is defective following three kinds of situations:
1) square is spread bigger than normal;
2) square is spread less than normal;
3) unevenness spreading square is excessive.
For the 1st) plant situation, existing reworking method continues diffusion when doing over again, for the 2nd) and 3) plant situation, do over again with reverse side after normally adopting four groove HF to clean.
But, do over again with reverse side after cleaning according to four groove HF, the phosphorus in back side diffusion is had no idea to remove, and the unevenness by increasing square is spread again to underproof diffusion square.
Summary of the invention
The embodiment of the present invention provides a kind of reworking method of defective polycrystalline diffusion square resistance, thoroughly to remove the phosphorus on diffusingsurface, makes diffusion square become even.
The embodiment of the present invention provides a kind of reworking method of defective polycrystalline diffusion square resistance, said method comprising the steps of: (1) configures the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of described sulfuric acid is 50 ~ 100L, the concentration of described sulfuric acid to be mass fraction be 98% the industrial concentrated sulfuric acid, the consumption of described nitric acid and hydrofluoric acid is 300L, the concentration of described nitric acid is 300 ~ 550g/L, and the concentration of described hydrofluoric acid is 20 ~ 60g/L; (2) containing described etching liquid into temperature is the cell body of 5 ~ 20 DEG C; (3) defective polycrystalline diffusion square resistance is inserted described etching liquid and carry out back of the body corrosion, the drift velocity of described defective polycrystalline diffusion square resistance in described etching liquid is 0.8 ~ 2m/min.
Alternatively, describedly defective polycrystalline diffusion square resistance is inserted described etching liquid and carry out back of the body corrosion and comprise: described defective polycrystalline diffusion square resistance face down is inserted described etching liquid and carry out the back of the body and corrode.
Alternatively, describedly defective polycrystalline diffusion square resistance is inserted described etching liquid and carry out back of the body corrosion and comprise: described defective polycrystalline diffusion square resistance is faced up and inserts described etching liquid and carry out the back of the body and corrode.
Alternatively, the consumption configuring described sulfuric acid during described etching liquid is 80L.
Alternatively, the concentration configuring described nitric acid during described etching liquid is 400g/L, and the concentration of described hydrofluoric acid is 30g/L.
Alternatively, the cell body that to contain into temperature by described etching liquid be 5 ~ 20 DEG C is specially: being contained by described etching liquid into temperature is the cell body of 8 DEG C.
Alternatively, carrying out the drift velocity of described defective polycrystalline diffusion square resistance in described etching liquid when the back of the body corrodes is 1.3m/min.
Alternatively, the consumption configuring described sulfuric acid during described etching liquid is 80L, the concentration of described nitric acid is 400g/L, the concentration of described hydrofluoric acid is 30g/L, the described cell body that to contain into temperature by described etching liquid be 5 ~ 20 DEG C is specially: being contained by described etching liquid into temperature is the cell body of 8 DEG C, described in when carrying out the back of the body corrosion drift velocity of described defective polycrystalline diffusion square resistance in described etching liquid be 1.3m/min.
From the reworking method of the defective polycrystalline diffusion square resistance that the invention described above embodiment provides, because said method defective polycrystalline diffusion square resistance is inserted the etching liquid configured by sulfuric acid, nitric acid and hydrofluoric acid carry out back of the body corrosion, to remove the effect of silicon chip back side and side phosphorus, remove phosphorosilicate glass simultaneously.Therefore, compared with doing over again with reverse side after adopting four groove HF to clean with prior art, the method that the embodiment of the present invention provides can remove the phosphorus in defective polycrystalline diffusion square resistance front or back side diffusion effectively, make the defective polycrystalline diffusion square resistance when doing over again have a clean diffusingsurface, follow-up when re-starting diffusion the uniformity of square higher.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those skilled in the art obtain, all belongs to the scope of protection of the invention.
Refer to accompanying drawing 1, be the reworking method schematic flow sheet of a kind of defective polycrystalline diffusion square resistance that the embodiment of the present invention provides, mainly comprise step:
S101, configure the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of described sulfuric acid is 50 ~ 100L, the concentration of described sulfuric acid to be mass fraction be 98% the industrial concentrated sulfuric acid, the consumption of described nitric acid and hydrofluoric acid is 300L, the concentration of described nitric acid is 300 ~ 550g/L, and the concentration of described hydrofluoric acid is 20 ~ 60g/L.
S102, being contained by described etching liquid into temperature is the cell body of 5 ~ 20 DEG C.
In embodiments of the present invention, can will configure etching liquid is contained in the descaling bath cell body of chain type low temperature pickler in step S101, such as, can will configure etching liquid is contained in the descaling bath cell body of chain type low temperature pickler of Rena manufacturer production in step S101.The temperature-controllable of cell body is within 5 ~ 20 DEG C.
S103, inserts described etching liquid by defective polycrystalline diffusion square resistance and carries out back of the body corrosion, and the drift velocity of described defective polycrystalline diffusion square resistance in described etching liquid is 0.8 ~ 2m/min.
In embodiments of the present invention, so-called defective polycrystalline diffusion square resistance refers to that polysilicon chip is after having carried out polycrystalline diffusion technology, after tested personnel's detection, testing result does not meet the diffusion square resistance of related request, when carrying out diffusion technology, its front (carrying out the one side of diffusion technology) and the back side (not carrying out the one side of diffusion technology, relative with the one side of carrying out diffusion technology) has also spread a certain amount of phosphorus.When defective polycrystalline diffusion square resistance being inserted etching liquid and carrying out back of the body corrosion, its drift velocity in described etching liquid can be controlled at 0.8 ~ 2m/min, back of the body corrosion fully can be carried out.Particularly, the belt speed of the chain type low temperature pickler of Rena manufacturer production can be controlled at 0.8 ~ 2m/min.
As one embodiment of the invention, defective polycrystalline diffusion square resistance being inserted etching liquid, to carry out back of the body corrosion can be described defective polycrystalline diffusion square resistance face down is inserted described etching liquid to carry out the back of the body and corrode, thus thoroughly washing the phosphorus of this polycrystalline diffusion square resistance front diffusion when carrying out diffusion technology, follow-up diffusion technology uses the front having washed phosphorus to spread.
As another embodiment of the present invention, defective polycrystalline diffusion square resistance being inserted etching liquid, to carry out back of the body corrosion can be faced up by described defective polycrystalline diffusion square resistance to insert described etching liquid and carry out the back of the body and corrode, thus thoroughly washing the phosphorus of this polycrystalline diffusion square resistance back side diffusion when carrying out diffusion technology, follow-up diffusion technology uses the back side having washed phosphorus to spread.
In embodiments of the present invention, when configuring the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid can be 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 300 ~ 550g/L, the concentration of hydrofluoric acid is 20 ~ 60g/L, and cell body temperature controls at 5 ~ 20 DEG C, and the drift velocity of defective polycrystalline diffusion square resistance in described etching liquid controls at 0.8 ~ 2m/min.
In an alternative embodiment of the invention, when configuring the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid can be 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 400g/L, the concentration of hydrofluoric acid is 30g/L, and cell body temperature controls at 5 ~ 20 DEG C, and the drift velocity of defective polycrystalline diffusion square resistance in described etching liquid controls at 0.8 ~ 2m/min.
In an alternative embodiment of the invention, when configuring the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid can be 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 300 ~ 550g/L, the concentration of hydrofluoric acid is 20 ~ 60g/L, and cell body temperature controls at 8 DEG C, and the drift velocity of defective polycrystalline diffusion square resistance in described etching liquid controls at 0.8 ~ 2m/min.
In an alternative embodiment of the invention, when configuring the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid can be 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 300 ~ 550g/L, the concentration of hydrofluoric acid is 20 ~ 60g/L, and cell body temperature controls at 5 ~ 20 DEG C, and the drift velocity of defective polycrystalline diffusion square resistance in described etching liquid controls at 1.3m/min.
In another preferred embodiment of the present invention, when configuring the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid can be 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 400g/L, the concentration of hydrofluoric acid is 30g/L, and cell body temperature controls at 8 DEG C, and the drift velocity of defective polycrystalline diffusion square resistance in described etching liquid controls at 1.3m/min.
From the reworking method of the defective polycrystalline diffusion square resistance that the invention described above embodiment provides, because said method defective polycrystalline diffusion square resistance is inserted the etching liquid configured by sulfuric acid, nitric acid and hydrofluoric acid carry out back of the body corrosion, to remove the effect of silicon chip back side and side phosphorus, remove phosphorosilicate glass simultaneously.Therefore, compared with doing over again with reverse side after adopting four groove HF to clean with prior art, the method that the embodiment of the present invention provides can remove the phosphorus in defective polycrystalline diffusion square resistance front or back side diffusion effectively, make the defective polycrystalline diffusion square resistance when doing over again have a clean diffusingsurface, follow-up when re-starting diffusion the uniformity of square higher.
In order to the effect of the method that the reworking method method of defective polycrystalline provided by the invention diffusion square resistance provides with prior art is clearly described, time below to configure the etching liquid mixed by sulfuric acid, nitric acid and hydrofluoric acid, the consumption of sulfuric acid is 80L, the consumption of nitric acid and hydrofluoric acid is 300L, the concentration of nitric acid is 400g/L, the concentration of hydrofluoric acid is 30g/L, cell body temperature control 8 DEG C, defective polycrystalline spreads the drift velocity of square resistance in described etching liquid and controls at 1.3m/min.First group (A group) defective polycrystalline diffusion square is inserted etching liquid and is carried out the back of the body when corroding, face down; Second group (B group) defective polycrystalline diffusion square is inserted etching liquid and is carried out the back of the body when corroding, and faces up; 3rd group (C group) defective polycrystalline diffusion square is done over again with reverse side after employing four groove HF cleans, and washes rear drying, then use the back side to spread as diffusingsurface.
In solar cell making process, qualified its average square (Ω/) of polycrystalline diffusion square is 65 ± 5, and variance is no more than 5, with following table one be do over again before the average square of A, B and C tri-groups defective polycrystalline diffusion square and variance yields thereof.
Group |
Average square (Ω/) |
Variance |
A |
49.23 |
2.21 |
B |
50.21 |
2.14 |
C |
49.34 |
1.25 |
Table one
After A, B and C tri-groups defective polycrystalline diffusion square carries out carrying on the back corrosion, carry out spreading the average square and variance yields thereof that record again with following table two.
Group |
Average square (Ω/) |
Variance |
A |
64.59 |
0.95 |
B |
63.29 |
1.01 |
C |
63.54 |
1.92 |
Table two
When doing over again, the mean value of the thickness A group of back of the body corrosion etching is 1.23 μm, the mean value of B group is 1.27 μm, and current diffusion technology junction depth at 600nm (0.6 μm) below, therefore, the phosphorus in diffusion can all etch away by the back of the body corrosion that the embodiment of the present invention provides.
Following table three is electrical property contrasts that A, B and C tri-groups defective polycrystalline diffusion square records after doing over again
Table three
From the electrical property contrast shown in above-mentioned table three, the efficiency of A group (namely inserting the defective polycrystalline diffusion square of face down when etching liquid carries out carrying on the back corrosion) back of the body corrosion is best, its electric current and voltage is all more satisfactory, and the voltage of B group (namely inserting heads defective polycrystalline diffusion square when etching liquid carries out carrying on the back corrosion) is also more satisfactory, but electric current is obviously undesirable, its main cause is that it is after the phosphorus thoroughly washing back side diffusion, use the back side having washed phosphorus to spread in follow-up diffusion technology, and the reflectivity at the back side is obviously large than front; The C group not only uniformity is bad, and little obviously than A group of its electric current.
Above the reworking method of the defective polycrystalline diffusion square resistance that the embodiment of the present invention provides is described in detail, apply specific case herein to set forth principle of the present invention and execution mode, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping; Meanwhile, for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.