阅读说明：本技术 一种砷化镓薄膜太阳电池及制作方法 (Gallium arsenide thin film solar cell and manufacturing method thereof ) 是由 李俊承 徐培强 吴洪清 白继锋 米万里 熊珊 潘彬 王向武 张银桥 于 2021-03-23 设计创作，主要内容包括：本发明涉及砷化镓薄膜电池技术领域,尤其涉及一种砷化镓薄膜太阳电池及制作方法。一种砷化镓薄膜太阳电池,包括外延层、聚酰亚胺薄膜层和键合层,外延层上均匀间隔开设有腐蚀槽,腐蚀槽把外延层分割成具有间距的阵列状外延层,与外延层接触的键合层上均匀间隔开设有走道,走道把与外延层接触的键合层分割成具有间距的阵列状键合层。一种砷化镓薄膜太阳电池的制作方法,使用ICP或化学腐蚀的办法,外延层和键合层被分割为具有间距的微小的阵列,并且实现阵列之间的互联,使得有源层进行小面积分割互联,有效减少的外延层应力的释放,解决了由于聚酰亚胺薄膜无法抵抗外延层的应力而造成整个器件是弯曲的问题。(The invention relates to the technical field of gallium arsenide thin film batteries, in particular to a gallium arsenide thin film solar battery and a manufacturing method thereof. A gallium arsenide thin film solar cell comprises an epitaxial layer, a polyimide thin film layer and a bonding layer, wherein corrosion grooves are uniformly arranged on the epitaxial layer in a spaced mode, the epitaxial layer is divided into array-shaped epitaxial layers with intervals by the corrosion grooves, walkways are uniformly arranged on the bonding layer in contact with the epitaxial layer in a spaced mode, and the bonding layer in contact with the epitaxial layer is divided into array-shaped bonding layers with intervals by the walkways. A method for manufacturing a gallium arsenide thin film solar cell uses an ICP (inductively coupled plasma) or chemical corrosion method, an epitaxial layer and a bonding layer are divided into tiny arrays with intervals, interconnection among the arrays is achieved, active layers are subjected to small-area division interconnection, release of stress of the epitaxial layer is effectively reduced, and the problem that the whole device is bent due to the fact that a polyimide thin film cannot resist stress of the epitaxial layer is solved.)

1. The utility model provides a gallium arsenide thin film solar cell, includes epitaxial layer, polyimide film layer and bonding layer, polyimide film layer both sides are provided with bonding layer, one side be provided with on the bonding layer epitaxial layer, its characterized in that:

etching grooves are uniformly arranged on the epitaxial layer at intervals, the etching grooves divide the epitaxial layer into array-shaped epitaxial layers with intervals, the bottom of each etching groove is the surface of the bonding layer, walkways are uniformly arranged on the bonding layer in contact with the epitaxial layer at intervals, the walkways divide the bonding layer in contact with the epitaxial layer into array-shaped bonding layers with intervals, the bottom of each walkway is the surface of the polyimide film layer, and the walkways are positioned below the etching grooves and in one-to-one correspondence;

the silicon wafer is characterized by further comprising N electrodes, P electrodes and interconnection electrodes, wherein each bonding layer is provided with a P electrode, the P electrodes are uniformly distributed in the corrosion groove at intervals, each epitaxial layer is provided with an N electrode, the interconnection electrodes are arranged between the adjacent P electrodes and the N electrodes, and the adjacent array-shaped bonding layers and the adjacent array-shaped epitaxial layers are connected together through the interconnection electrodes positioned between the adjacent array-shaped bonding layers and the array-shaped epitaxial layers;

and a BCB adhesive layer is coated on the surface of the epitaxial layer, in the corrosion groove and in the channel, and an antireflection film layer is coated on the surface of the BCB adhesive layer.

2. The gallium arsenide thin film solar cell of claim 1, wherein:

the structure of the epitaxial layer is a triple junction, a double junction or a single junction.

3. The gallium arsenide thin film solar cell of claim 1, wherein:

the electrode structures of the N electrode and the P electrode are AuGe/Ti/Au/Ag/Au, the overall thickness is 3 mu m, and the thickness of Au accounts for about 11%.

4. The gallium arsenide thin film solar cell of claim 1, wherein:

the interconnection electrode material is Ag, the thickness is 40K A, and the thickness of the bonding layer is 15K A.

5. A method for manufacturing a gallium arsenide thin film solar cell as claimed in any of claims 1-4, comprising the steps of:

s1: growing an epitaxial structure in an inverted mode, and growing the epitaxial structure of the multi-junction solar cell on the N-type GaAs substrate by using an organic metal chemical vapor deposition method to form an epitaxial layer on the N-type GaAs substrate;

s2: metal evaporation, namely cleaning the epitaxial layer, the GaAs temporary substrate sheet and the polyimide film, evaporating Au on the surface of one side of the epitaxial layer far away from the GaAs substrate and the surface of one side of the GaAs temporary substrate sheet close to the epitaxial layer after cleaning, evaporating Ti and Au on the surfaces of two sides of the polyimide film in sequence, and annealing the epitaxial layer, the GaAs temporary substrate and the polyimide film after evaporation;

s3: bonding, namely sequentially superposing the epitaxial layer, the polyimide film and the GaAs temporary substrate together, wherein during bonding, the metal faces the metal surface, so that a metal bonding layer is formed between the epitaxial layer and the polyimide film and between the GaAs temporary substrate and the polyimide film, and after bonding, a protective layer film is deposited on the surface of one side, away from the polyimide film, of the GaAs temporary substrate surface;

s4: removing the GaAs substrate, namely removing the GaAs substrate on one side of the epitaxial layer by using a chemical solution corrosion method;

s5: manufacturing a table board, namely etching the epitaxial layer by using inductively coupled plasma until the metal layer is etched, so that etching grooves are formed on the epitaxial layer at uniform intervals, and the epitaxial layer is divided into a plurality of epitaxial layers;

s6: manufacturing an N/P electrode, namely manufacturing an electrode pattern by using negative photoresist, evaporating a metal electrode, and then performing a stripping method to manufacture the electrodes of an N surface and a P surface at one time, so that an N electrode is evaporated on each epitaxial layer, and a P electrode is evaporated on a bonding layer in each corrosion groove;

s7: making the channel by using photoetching mask technology, making channel pattern at the bottom of the etched groove by using photoresist, and using I₂Etching the Au layer of the bonding layer by using a KI aqueous solution, and corroding the Ti layer of the bonding layer by using a HF solution to etch a walkway on the bottom of each corrosion groove, so that the bonding layer is divided into a plurality of blocks, and the walkways are positioned between two adjacent P electrodes;

s8: BCB filling, namely coating a layer of tackifier on the surface of the array-shaped epitaxial layer, the surface of the corrosion groove and the surface of the channel after the channel manufacturing step, coating a layer of BCB glue to form a BCB glue layer, and curing the BCB glue after coating;

s9: flattening and windowing an electrode, curing the BCB glue filled in the step BCB, then carrying out chemical mechanical polishing on the surface of the BCB glue layer, flattening the surface of the BCB glue layer, taking one side of the BCB glue layer as the front side of the solar cell, and removing the BCB glue on the N/P electrode by utilizing a photoetching mask and an ICP technology;

s10: manufacturing an interconnection electrode, namely evaporating an electrode for connecting the adjacent N electrode and the adjacent P electrode by utilizing a negative photoresist stripping technology and an electron beam evaporation technology, and forming an interconnection electrode between the adjacent N electrode and the adjacent P electrode so as to connect the two adjacent bonding layers and the epitaxial layer together through the interconnection electrode;

s11: preparing an antireflection film, and sequentially evaporating on the front surface of the solar cell by using an electron beam evaporation technologyUpper Ti₃O₅And Al₂O₃Forming an antireflection film layer, manufacturing an antireflection film etching graph by using a photoetching mask technology, and corroding the antireflection film on the N/P electrode and the interconnection electrode by using a HF solution;

s12: removing the GaAs temporary substrate, coating a layer of photoresist on the front surface of the solar cell to serve as a protective layer, further protecting by attaching a layer of pyrolytic film, thinning the GaAs temporary substrate to 100 mu m by using a grinding wheel grinder, and then using NH₄OH and H₂O₂The residual GaAs temporary substrate is etched until the GaAs substrate is completely etched.

6. The method of claim 5, wherein the method comprises:

in the step of metal evaporation, the organic cleaning mode comprises the steps of ultrasonic cleaning for 5min by using acetone, ultrasonic cleaning for 5min by using isopropanol, washing by using deionized water, dehydrating for 1min by using the isopropanol and drying for 10min by using a 110 ℃ oven in sequence;

in the step of metal evaporation, the epitaxial layer, the GaAs temporary substrate and the polyimide film are annealed in N₂The annealing is carried out in the environment, the annealing temperature is 320 ℃, and the annealing time is 10 min.

7. The method of claim 5, wherein the method comprises:

in the step bonding, the bonding conditions are: the pressure is 7000 kgf-9000 kgf, the temperature rises and falls in three stages, the first stage is 240 ℃, the holding time is 5min, the second stage is 320 ℃, the holding time is 10min, and the third stage is 100 ℃, and the holding time is 5 min;

in step bonding, a Si of a protective layer film 3000A deposited on the surface of the GaAs temporary substrate face on the side away from the polyimide film₃N₄A film;

in the step bonding, the thickness of Au evaporated on the battery epitaxial wafer and the GaAs temporary substrate is 10K A, and the thicknesses of Ti and Au evaporated on both sides of the polyimide film are 1K A and 4K A respectively;

in the step of GaAs substrate removal, the chemical solution composition used is NH₄OH、H₂O₂、H₂O, in a ratio of 1:1:5 or 1:5:5, the etching being carried out in a cooling bath.

8. The method of claim 5, wherein the method comprises:

in the step of mesa fabrication, when the epitaxial layer is etched by using the inductively coupled plasma, the gas used is Cl₂、HBr、BCl₃、O₂The total flow is controlled to be 50sccm, the cavity pressure is 0.5Pa, the upper electrode power is 300w, and the lower electrode power is 50 w;

in the step of manufacturing the table top, the integral depth of the etching groove is 5-6 microns, each epitaxial layer is used as a table top, and the size of each table top is 100 microns multiplied by 100 microns;

in the step of manufacturing the N/P electrode, the electrode has the structure of AuGe/Ti/Au/Ag/Au, the whole thickness is 3 mu m, wherein the thickness of Au accounts for about 11%;

in the step of making the walkway, in using I₂And KI in an aqueous solution, wherein I₂The mass ratio of the KI to the KI is 1:5, the solution concentration is 3-5 mol/L, and the use temperature is 40 +/-2 ℃;

in the step of making the walkway, the concentration of the used HF solution is 0.15-0.2 mol/L.

9. The method of claim 5, wherein the method comprises:

in the step of BCB filling, the BCB glue is coated by using a spin coating method, wherein the spin coating parameters are as follows: the first rotation is 1200rpm and the time is 10s, the second rotation is 2500rpm and the time is 30 s;

in the step of BCB filling, the method for carrying out curing treatment on the BCB glue is that N is₂Annealing at 200 deg.C for 30 min;

in the step of flattening and windowing an electrode, when the surface of the BCB adhesive layer is subjected to chemical mechanical polishing, a polyurethane polishing pad is used for polishing, the polishing solution is alkaline, the pH value is 9.6-10.9, the polishing pressure is 0.2kgf, and the time is 10 min;

in the step of flattening and electrode windowing, the gas used by ICP is SF₆、O₂Total flow rate of 50sccm, where O₂5sccm, pressure 2Pa, top electrode power 500w, and bottom electrode power 100 w.

10. The method of claim 5, wherein the method comprises:

in the step of manufacturing an interconnection electrode, the interconnection electrode is made of Ag and has a thickness of 40K A, and when an electron beam evaporation technology is used, the angle of an evaporation plating pot is controlled at 70 degrees, and the rotating speed is 12 rpm;

in the step of forming the antireflection film, Ti₃O₅And Al₂O₃The thickness of the HF solution is 300A and 600A respectively, and the concentration of the HF solution is 0.12 mol/L;

in the step of removing the GaAs temporary substrate, the thickness of the coated photoresist is 2-2.5 i mu m, the thickness of the pyrolytic film is 500 mu m, and NH is used₄OH and H₂O₂The mass ratio of each component in the aqueous solution of (1) is NH₄OH：H₂O₂：H₂O=1:1:5。

Technical Field

The invention relates to the technical field of gallium arsenide thin film batteries, in particular to a gallium arsenide thin film solar battery and a manufacturing method thereof.

Background

Typically, epitaxial structures for thin film GaAs cells are grown upside down. And is typically a large mismatch structure for efficiency improvement. One consequence of this is that the epitaxial layer itself is very stressed and is typically rolled up automatically after the original epitaxial substrate is removed. However, it is now common to transfer the epitaxial layer to the polyimide film, which has stable properties and strong environmental suitability and can work in an out-of-ground space. However, since the polyimide film is thin and cannot resist the stress of the epitaxial layer, the whole device is bent, which causes great difficulty in application of the gallium arsenide thin film battery.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides the gallium arsenide thin film solar cell, an ICP (inductively coupled plasma) or chemical corrosion method is used, the epitaxial layer and the bonding layer are divided into tiny arrays with intervals, and the interconnection among the arrays is realized, so that the active layer is subjected to small area division interconnection, and the stress of the epitaxial layer is effectively reduced; meanwhile, BCB is filled in the grooves on the front side of the solar cell, namely the surface of the epitaxial layer, the corrosion groove and the channel, and surface planarization is realized by matching with a CMP technology, so that the reliability of interconnection between the epitaxial layer and the small units of the bonding layer array is effectively ensured, and the interconnection yield is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a gallium arsenide thin film solar cell, which comprises an epitaxial layer, a polyimide thin film layer and bonding layers, wherein the bonding layers are arranged on two sides of the polyimide thin film layer, the epitaxial layer is arranged on the bonding layer on one side, etching grooves are uniformly arranged on the epitaxial layer at intervals and divide the epitaxial layer into array-shaped epitaxial layers with intervals, the bottom of each etching groove is the surface of the bonding layer, walkways are uniformly arranged on the bonding layer in contact with the epitaxial layer at intervals and divide the bonding layer in contact with the epitaxial layer into array-shaped bonding layers with intervals, the bottom of each walkway is the surface of the polyimide thin film layer, and the walkways are positioned below the etching grooves and are in one-to-one correspondence relationship;

the silicon wafer is characterized by further comprising N electrodes, P electrodes and interconnection electrodes, wherein each bonding layer is provided with a P electrode, the P electrodes are uniformly distributed in the corrosion groove at intervals, each epitaxial layer is provided with an N electrode, the interconnection electrodes are arranged between the adjacent P electrodes and the N electrodes, and the adjacent array-shaped bonding layers and the adjacent array-shaped epitaxial layers are connected together through the interconnection electrodes positioned between the adjacent array-shaped bonding layers and the array-shaped epitaxial layers;

and a BCB adhesive layer is coated on the surface of the epitaxial layer, in the corrosion groove and in the channel, and an antireflection film layer is coated on the surface of the BCB adhesive layer.

As a further improvement of the technical scheme, the structure of the epitaxial layer is a triple junction, a double junction or a single junction.

As a further improvement of the technical scheme, the electrode structures of the N electrode and the P electrode are AuGe/Ti/Au/Ag/Au, the overall thickness is 3 mu m, and the thickness of Au accounts for about 11%.

As a further improvement of the above technical solution, the interconnect electrode material is Ag with a thickness of 40K a, and the bonding layer has a thickness of 15K a.

The invention also provides a manufacturing method of the gallium arsenide thin film solar cell, which comprises the following steps:

and (3) inverted growth of an epitaxial structure: growing an epitaxial structure of the multi-junction solar cell on the N-type GaAs substrate by using an organic metal chemical vapor deposition method, so that an epitaxial layer is formed on the N-type GaAs substrate;

metal evaporation: cleaning the epitaxial layer, the GaAs temporary substrate sheet and the polyimide film, evaporating Au on the surface of one side of the epitaxial layer far away from the GaAs substrate and the surface of one side of the GaAs temporary substrate sheet close to the epitaxial layer after cleaning, evaporating Ti and Au on the surfaces of two sides of the polyimide film in sequence, and annealing the epitaxial layer, the GaAs temporary substrate and the polyimide film after evaporation;

bonding: sequentially superposing the epitaxial layer, the polyimide film and the GaAs temporary substrate together, wherein during bonding, the metal faces to the metal surface, so that a metal bonding layer is formed between the epitaxial layer and the polyimide film and between the GaAs temporary substrate and the polyimide film, and after bonding, a protective layer film is deposited on the surface of one side, away from the polyimide film, of the GaAs temporary substrate surface;

removing the GaAs substrate: removing the GaAs substrate on one side of the epitaxial layer by using a chemical solution corrosion method;

manufacturing a table top: etching the epitaxial layer by using inductively coupled plasma until the metal layer is etched, so that etching grooves are formed on the epitaxial layer at uniform intervals, and the epitaxial layer is divided into a plurality of epitaxial layers;

manufacturing an N/P electrode: manufacturing an electrode pattern by using negative photoresist, evaporating a metal electrode, and then carrying out stripping to manufacture electrodes with an N surface and a P surface at one time, so that an N electrode is evaporated on each epitaxial layer, and a P electrode is evaporated on a bonding layer in each corrosion groove;

manufacturing a walkway: firstly, using photoetching mask technology, utilizing photoresist to make walkway pattern at the bottom of etched groove, using I₂Etching the Au layer of the bonding layer by using a KI aqueous solution, and corroding the Ti layer of the bonding layer by using a HF solution to etch a walkway on the bottom of each corrosion groove, so that the bonding layer is divided into a plurality of blocks, and the walkways are positioned between two adjacent P electrodes;

BCB filling: coating a layer of tackifier on the surface of the array-shaped epitaxial layer, the surface of the corrosion groove and the surface of the walkway after the walkway manufacturing step, coating a layer of BCB glue to form a BCB glue layer, and curing the BCB glue after coating;

flattening and windowing an electrode: after the BCB glue filled in the step BCB is solidified, carrying out chemical mechanical polishing on the surface of the BCB glue layer, flattening the surface of the BCB glue layer, taking one side of the BCB glue layer as the front side of the solar cell, and removing the BCB glue on the N/P electrode by utilizing a photoetching mask and an ICP technology;

manufacturing an interconnection electrode: evaporating an electrode for connecting the adjacent N electrode and the P electrode by utilizing a negative photoresist stripping technology and an electron beam evaporation technology, and forming an interconnection electrode between the adjacent N electrode and the adjacent P electrode, so that the two adjacent bonding layers and the epitaxial layer are connected together through the interconnection electrode;

preparing an antireflection film: sequentially evaporating Ti on the front surface of the solar cell by using an electron beam evaporation technology₃O₅And Al₂O₃Forming an antireflection film layer, manufacturing an antireflection film etching graph by using a photoetching mask technology, and corroding the antireflection film on the N/P electrode and the interconnection electrode by using a HF solution;

removing the GaAs temporary substrate: coating a layer of photoresist on the front surface of the solar cell to serve as a protective layer, further protecting by attaching a layer of pyrolytic film, thinning the GaAs temporary substrate to 100 mu m by using a grinding wheel grinder, and then using NH₄OH and H₂O₂The residual GaAs temporary substrate is etched until the GaAs substrate is completely etched.

As a further improvement of the technical scheme, in the step of metal evaporation, the organic cleaning mode comprises the steps of ultrasonic cleaning for 5min by using acetone, ultrasonic cleaning for 5min by using isopropanol, washing by using deionized water, dehydrating for 1min by using the isopropanol and drying for 10min by using a 110 ℃ oven in sequence;

in the step of metal evaporation, the epitaxial layer, the GaAs temporary substrate and the polyimide film are annealed in N₂The annealing is carried out in the environment, the annealing temperature is 320 ℃, and the annealing time is 10 min.

As a further improvement of the above technical solution, in the step bonding, the bonding conditions are: the pressure is 7000 kgf-9000 kgf, the temperature rises and falls in three stages, the first stage is 240 ℃, the holding time is 5min, the second stage is 320 ℃, the holding time is 10min, and the third stage is 100 ℃, and the holding time is 5 min;

in step bonding, a Si of a protective layer film 3000A deposited on the surface of the GaAs temporary substrate face on the side away from the polyimide film₃N₄A film;

in the step bonding, the thickness of Au evaporated on the battery epitaxial wafer and the GaAs temporary substrate is 10K A, and the thicknesses of Ti and Au evaporated on both sides of the polyimide film are 1K A and 4K A respectively;

in the step of GaAs substrate removal, the chemical solution composition used is NH₄OH、H₂O₂、H₂O, in a ratio of 1:1:5 or 1:5:5, the etching being carried out in a cooling bath.

As a further improvement of the technical scheme, in the step mesa manufacture, when the epitaxial layer is etched by using the inductively coupled plasma, the used gas is Cl₂、HBr、BCl₃、O₂The total flow is controlled to be 50sccm, the cavity pressure is 0.5Pa, the upper electrode power is 300w, and the lower electrode power is 50 w;

in the step of manufacturing the table top, the integral depth of the etching groove is 5-6 microns, each epitaxial layer is used as a table top, and the size of each table top is 100 microns multiplied by 100 microns;

in the step of manufacturing the N/P electrode, the electrode has the structure of AuGe/Ti/Au/Ag/Au, the whole thickness is 3 mu m, wherein the thickness of Au accounts for about 11%;

in the step of making the walkway, in using I₂And KI in an aqueous solution, wherein I₂The mass ratio of the KI to the KI is 1:5, and the concentration of the solution is 3 mol/L-5 mol-L, the using temperature is 40 +/-2 ℃;

in the step of making the walkway, the concentration of the used HF solution is 0.15-0.2 mol/L.

As a further improvement of the above technical solution, in the step of BCB filling, BCB glue is coated by spin coating, where the spin coating parameters are: the first rotation is 1200rpm and the time is 10s, the second rotation is 2500rpm and the time is 30 s;

in the step of BCB filling, the method for carrying out curing treatment on the BCB glue is that N is₂Annealing at 200 deg.C for 30 min;

in the step of flattening and windowing an electrode, when the surface of the BCB adhesive layer is subjected to chemical mechanical polishing, a polyurethane polishing pad is used for polishing, the polishing solution is alkaline, the pH value is 9.6-10.9, the polishing pressure is 0.2kgf, and the time is 10 min;

in the step of flattening and electrode windowing, the gas used by ICP is SF₆、O₂Total flow rate of 50sccm, where O₂5sccm, pressure 2Pa, top electrode power 500w, and bottom electrode power 100 w.

As a further improvement of the above technical solution, in the step of manufacturing the interconnection electrode, the interconnection electrode material is Ag, the thickness is 40K a, and when using an electron beam evaporation technique, the angle of the evaporation plating pot is controlled at 70 ° and the rotation speed is 12 rpm;

in the step of forming the antireflection film, Ti₃O₅And Al₂O₃The thickness of the HF solution is 300A and 600A respectively, and the concentration of the HF solution is 0.12 mol/L;

in the step of removing the GaAs temporary substrate, the thickness of the coated photoresist is 2-2.5 i mu m, the thickness of the pyrolytic film is 500 mu m, and NH is used₄OH and H₂O₂The mass ratio of each component in the aqueous solution of (1) is NH₄OH：H₂O₂：H₂O=1:1:5。

The invention has the beneficial effects that: 1. by using an ICP (inductively coupled plasma) or chemical corrosion method, the epitaxial layer and the bonding layer are divided into tiny arrays with intervals, and the interconnection among the arrays is realized, so that the active layer is subjected to small-area division interconnection, the stress release of the epitaxial layer is effectively reduced, and the problem that the whole device is bent due to the fact that the polyimide film cannot resist the stress of the epitaxial layer is solved.

2. BCB is filled in the grooves on the front side of the solar cell, namely the surface of the epitaxial layer, the corrosion groove and the channel, and surface planarization is realized by matching with a CMP technology, so that the reliability of interconnection between the epitaxial layer and the small units of the bonding layer array is effectively ensured, and the interconnection yield is improved.

Drawings

Fig. 1 is a schematic structural diagram of a solar cell according to an embodiment.

Fig. 2 is a schematic partial structure diagram of a solar cell according to an embodiment.

Wherein the figures include the following reference numerals: 1. the chip comprises an epitaxial layer, 2, a polyimide film layer, 3, a bonding layer, 4, a corrosion groove, 5, a channel, 6, an N electrode, 7, a P electrode, 8, an interconnection electrode, 9, a BCB adhesive layer, 10 and an antireflection film layer.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for completeness and fully convey the scope of the invention to the skilled person.

Example 1

As shown in fig. 1-2, this embodiment provides a gallium arsenide thin film solar cell, which includes an epitaxial layer 1, a polyimide thin film layer 2, and bonding layers 3, where the bonding layers 3 are disposed on two sides of the polyimide thin film layer 2, the epitaxial layer 3 on one side is disposed with the epitaxial layer 1, etching grooves 4 are uniformly spaced on the epitaxial layer 1, the epitaxial layer 1 is divided into array-shaped epitaxial layers 1 with spaces by the etching grooves 4, the bottom of each etching groove 4 is the surface of the bonding layer 3, walkways 5 are uniformly spaced on the bonding layer 3 in contact with the epitaxial layer 1, the bonding layer 3 in contact with the epitaxial layer 1 is divided into array-shaped bonding layers 3 with spaces by the walkways 5, the bottoms of the walkways 5 are the surfaces of the polyimide thin film layer 2, and the walkways 5 are located below the etching grooves 4 and are in a one-to-one; the silicon wafer further comprises N electrodes 6, P electrodes 7 and interconnection electrodes 8, wherein each bonding layer 3 is provided with the P electrodes 7, the P electrodes 7 are uniformly distributed in the corrosion groove 4 at intervals, each epitaxial layer 1 is provided with the N electrodes 6, the interconnection electrodes 8 are arranged between the adjacent P electrodes 7 and the adjacent N electrodes 6, and the adjacent array-shaped bonding layers 3 and the adjacent array-shaped epitaxial layers 1 are connected together through the interconnection electrodes 8 positioned between the adjacent array-shaped bonding layers and the array-shaped epitaxial layers; a BCB glue layer 9 is coated on the surface of the epitaxial layer 1, in the corrosion groove 4 and in the runner 5, and an antireflection film layer 10 is coated on the surface of the BCB glue layer 9.

Further, the structure of the epitaxial layer 1 is a triple junction, a double junction or a single junction, the electrode structures of the N electrode 6 and the P electrode 7 are AuGe/Ti/Au/Ag/Au, the overall thickness is 3 μm, wherein the Au thickness accounts for about 11%, the material of the interconnection electrode 8 is Ag, the thickness is 40K a, and the thickness of the bonding layer 3 is 15K a.

The epitaxial layer 1 and the bonding layer 3 are divided into tiny arrays with intervals, and the interconnection among the arrays is realized, so that the active layer is subjected to small-area division interconnection, the stress of the epitaxial layer 1 is effectively reduced, and the problem that the whole device is bent due to the fact that the polyimide film cannot resist the stress of the epitaxial layer 1 is solved; meanwhile, BCB is filled in the grooves on the front side of the solar cell, namely the surface of the epitaxial layer 1, the corrosion groove 4 and the walkway 5, and surface planarization is realized by matching with a CMP technology, so that the reliability of interconnection between the epitaxial layer 1 and the bonding layer 3 array small units is effectively ensured, and the interconnection yield is improved.

Example 2

The embodiment provides a method for manufacturing a gallium arsenide thin film solar cell, which comprises the following steps:

s1, growing an epitaxial structure of the multi-junction solar cell on the N-type GaAs substrate in an inverted mode by using an organic metal chemical vapor deposition method, and forming an epitaxial layer on the N-type GaAs substrate;

s2, metal evaporation, namely cleaning the epitaxial layer, the GaAs temporary substrate piece and the polyimide film, evaporating Au on the surface of the epitaxial layer far away from the GaAs substrate and the surface of the GaAs temporary substrate piece near the epitaxial layer after cleaning, sequentially evaporating Ti and Au on the surfaces of the two sides of the polyimide film, and annealing the epitaxial layer, the GaAs temporary substrate and the polyimide film after evaporation;

s3, bonding, namely sequentially overlapping the epitaxial layer, the polyimide film and the GaAs temporary substrate together, wherein during bonding, the metal faces the metal surface, so that a metal bonding layer is formed between the epitaxial layer and the polyimide film and between the GaAs temporary substrate and the polyimide film, and after bonding, a protective layer film is deposited on the surface of one side, away from the polyimide film, of the GaAs temporary substrate surface;

s4, removing the GaAs substrate, namely removing the GaAs substrate on one side of the epitaxial layer by using a chemical solution corrosion method;

s5, manufacturing a table top, etching the epitaxial layer by using inductively coupled plasma until the metal layer is etched, forming a corrosion groove on the epitaxial layer at uniform intervals, and dividing the epitaxial layer into a plurality of epitaxial layers;

s6, manufacturing an N/P electrode, namely manufacturing an electrode pattern by using negative photoresist, evaporating a metal electrode, and then performing a stripping method to manufacture the electrodes of an N surface and a P surface at one time, so that an N electrode is evaporated on each epitaxial layer, and a P electrode is evaporated on a bonding layer in each corrosion groove;

s7 making the channel by using photoetching mask technology, making channel pattern on the bottom of the etched groove by using photoresist, and using I₂Etching the Au layer of the bonding layer by using a KI aqueous solution, and corroding the Ti layer of the bonding layer by using a HF solution to etch a walkway on the bottom of each corrosion groove, so that the bonding layer is divided into a plurality of blocks, and the walkways are positioned between two adjacent P electrodes;

s8, BCB filling, namely coating a layer of tackifier on the surface of the array-shaped epitaxial layer, the surface of the corrosion groove and the surface of the walkway after the walkway manufacturing step, coating a layer of BCB glue to form a BCB glue layer, and curing the BCB glue after coating;

s9, flattening and windowing an electrode, curing the BCB glue filled in the step BCB, then carrying out chemical mechanical polishing on the surface of the BCB glue layer, flattening the surface of the BCB glue layer, taking one surface of the BCB glue layer as the front surface of the solar cell, and removing the BCB glue on the N/P electrode by utilizing a photoetching mask and an ICP technology;

s10, manufacturing an interconnection electrode, namely evaporating an electrode for connecting the adjacent N electrode and the adjacent P electrode by utilizing a negative photoresist stripping technology and an electron beam evaporation technology, and forming an interconnection electrode between the adjacent N electrode and the adjacent P electrode so as to connect the two adjacent bonding layers and the epitaxial layer together through the interconnection electrode;

s11 preparing the anti-reflection film, and sequentially evaporating Ti on the front surface of the solar cell by using an electron beam evaporation technology₃O₅And Al₂O₃Forming an antireflection film layer, manufacturing an antireflection film etching graph by using a photoetching mask technology, and corroding the antireflection film on the N/P electrode and the interconnection electrode by using a HF solution;

s12, removing the GaAs temporary substrate, coating a layer of photoresist on the front side of the solar cell to serve as a protective layer, further protecting by attaching a layer of pyrolytic film, then thinning the GaAs temporary substrate to 100 mu m by using a grinding wheel grinder, and then using NH₄OH and H₂O₂The residual GaAs temporary substrate is etched until the GaAs substrate is completely etched.

The detailed manufacturing process is as follows:

1. and (3) growing an epitaxial structure of the multi-junction solar cell on the N-type GaAs substrate by using an organic metal chemical vapor deposition method. The epitaxial structure may be a triple junction, a double junction, or a single junction. The three-junction cell grows in the order of InGaP, GaAs and InGaAs, the two-junction cell grows in the order of InGaP and GaAs, and the single junction can be single-junction GaAs or single-junction InGaP; the sub-cells are connected by a tunnel junction, which may be GaAs/AlGaAs or GaAs/GaInP.

2. And evaporating bonding layer metal. And cleaning the solar cell epitaxial wafer, the temporary substrate GaAs wafer and Polyimide (PI). The method for cleaning the solar cell epitaxial wafer and the GaAs temporary substrate wafer is organic cleaning. Ultrasonic treating with acetone for 5min, ultrasonic treating with isopropanol for 5min, washing with deionized water, dehydrating with isopropanol for 1min, and oven drying at 110 deg.C for 10 min. The thickness of the selected GaAs temporary substrate is 500 mu m +/-15 mu m.

And (4) carrying out metal evaporation on the bonding layer by using an electron beam evaporation method after cleaning. Cell epitaxial wafer, GaAs temporary substrate, and vapor deposition methodAu, thickness 10k A; performing double-sided evaporation of Ti/Au on the PI film, wherein the thickness of Ti is 1K A, and the thickness of Au is 4K A; after evaporation, annealing the solar cell epitaxial wafer, the GaAs temporary substrate and the PI film at 320 ℃ for 10min, wherein N is₂And (4) environment.

3. The sandwich bonding refers to a method for sequentially stacking a solar cell epitaxial wafer, a PI film and a temporary GaAs substrate together to form a whole structure similar to a sandwich structure and then bonding and molding at one time; when bonding, the metal faces the metal, and the bonding conditions are as follows: the pressure is 7000 kgf-9000 kgf, the temperature rises and falls in three stages, the first stage is 240 ℃, the holding time is 5min, the second stage is 320 ℃, the holding time is 10min, and the third stage is 100 ℃, and the holding time is 5 min; after bonding, a 3000 a thin film of Si3N4 was deposited as a protective layer on the GaAs temporary substrate side.

4. And removing the GaAs substrate of the battery epitaxial wafer by using a chemical solution corrosion method. The chemical solution component used is NH₄OH、H₂O₂、H₂O, the ratio can be 1:1:5 or 1:5:5, and the corrosion is carried out in a cooling tank, so as to absorb the heat released by the reaction.

5. And (5) manufacturing a table top. And etching the epitaxial layer by using inductively coupled plasma until the metal layer is etched, wherein the integral groove depth is 5-6 mu m, and the mesa size is 100 mu m multiplied by 100 mu m. The gas used is Cl₂、HBr、BCl₃、O₂The total flow rate of the gas is controlled to be 50sccm, the pressure of the cavity is 0.5Pa, the power of the upper electrode is 300w, and the power of the lower electrode is 50 w. Specifically, O is added to the etching gas₂In order to etch steps without right angles, O₂The flow rate of the liquid is 2-5%, the step angle is 105-120 degrees, and the liquid has no right-angled steps, so that subsequent filling and passivation are facilitated.

6. And manufacturing an N/P electrode. And (3) manufacturing an electrode pattern by using negative photoresist, evaporating a metal electrode, and then stripping to manufacture the N-surface and P-surface electrodes at one time.

The structure of the electrode of the N-surface and P-surface electrodes is AuGe/Ti/Au/Ag/Au, the whole thickness is 3 mu m, wherein the thickness of Au accounts for about 11%.

7. And (5) manufacturing the walkway. Firstly, a photolithographic mask technology is used, and a path pattern is made by utilizing photoresist. Use of I₂KI aqueous solution, etching the gold, wherein I₂: KI =1:5 (mass ratio), the solution concentration is 3-5 mol/L, and the use temperature is 40 ℃ +/-2 ℃. And then corroding Ti by using an HF solution, wherein the concentration of the HF solution is 0.15-0.2 mol/L.

8. BCB fills and planarizes. BCB coating was performed using spin coating and the surface was coated with AP3000 adhesion promoter prior to BCB coating. BCB spin coating parameters are as follows: the first rotation was 1200rpm for 10s, the second rotation was 2500rpm for 30 s. After coating, BCB is cured by N₂Annealing at 200 ℃ for 30min under the environment, then carrying out chemical mechanical polishing, and flattening the surface of the BCB, wherein a polyurethane polishing pad is used for polishing, the polishing solution is alkaline, the pH value is 9.6-10.9, the polishing pressure is 0.2kgf, and the time is 10 min. After polishing, the BCB on the N/P electrode is removed by using a photolithographic mask and an ICP (inductively coupled plasma) technology. The gas used by ICP is SF₆、O₂Total flow rate of 50sccm, where O₂5sccm, pressure 2Pa, top electrode power 500w, and bottom electrode power 100 w.

9. And manufacturing an interconnection electrode. And (3) connecting electrodes by evaporation by using a negative adhesive stripping technology and an electron beam evaporation technology, wherein the electrode material is Ag and the thickness is 40K A. In particular, in order to make the connection electrode have good connection, disconnection is not caused. The angle of the evaporation plating pot is controlled at 70 degrees, and the rotating speed is 12 rpm.

10. And (4) manufacturing an antireflection film. And (3) evaporating the antireflection film material by using an electron beam evaporation technology. The material is sequentially Ti₃O₅And Al₂O₃The thicknesses are respectively 300A and 600A. Then, a photoetching mask technology is used for manufacturing an anti-reflection film etching pattern. And etching off the antireflection film on the electrode by using an HF solution, wherein the concentration of the HF solution is 0.12 mol/L.

11. And removing the temporary substrate. Firstly, coating a layer of photoresist with the thickness of 2-2.5 i mu m on the front surface of the battery to be used as a protective layer. Then sticking a pyrolytic film with the thickness of 500 mu m for further protection; the GaAs temporary substrate was then thinned to 100 μm using a wheel grinder, followed by NH₄OH：H₂O₂：H₂And O =1:1:5 solution, and etching the residual GaAs substrate until the GaAs substrate is completely etched.

The above examples are merely representative of preferred embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.