JP2014063848A - Integrated photoelectric conversion device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an integrated photoelectric conversion device manufacturing method which can improve conversion efficiency.SOLUTION: An integrated photoelectric conversion device manufacturing method comprises: sequentially laminating transparent conductive films 21-2n, photoelectric conversion layers 31', 32''-3n'', back electrodes 41-4n and conductive protection films 51-5n on a translucent substrate 1 and forming element isolation grooves 61 to 6n-1, element isolation grooves 71 to 7n-1 for connection and element division grooves 81 to 8n-1 in a manner such that a plurality of photoelectric conversion layers 31-3n are connected in series; and subsequently processing the photoelectric conversion layers 31', 32''-3n'', the back electrodes 41-4n and the conductive protection films 51-5n by a hydrogen plasma treatment by using a hydrogen atom-containing gas through the element division grooves 81 to 8n-1 (process (i)).

Description

  The present invention relates to a method for manufacturing an integrated photoelectric conversion device.

  Conventionally, an integrated photoelectric conversion device including at least one crystalline photoelectric conversion unit layer is known (Patent Document 1).

  In this photoelectric conversion device, a transparent electrode layer, at least one crystalline silicon-based photoelectric conversion unit layer, and a back electrode layer laminated on a transparent insulating substrate are separated by a separation groove so as to form a plurality of photoelectric conversion cells. In the photoelectric conversion device in which a plurality of photoelectric conversion cells are connected in series, the back electrode separation groove for separating the back electrode layer into a plurality of back electrodes is irradiated with a laser beam for scribing from the transparent substrate side. The transparent electrode layer is formed by blowing a predetermined region of the back electrode layer at the same time as the predetermined region of the conversion unit layer, and is observed in the metallographic microscope of the transparent electrode layer exposed in the region of the back electrode separation groove. It is characterized in that the ratio of the area causing discoloration or peeling representing the thermal damage is in the range of 2% or more and less than 10%.

  In Patent Document 1, in a photoelectric conversion device including at least one crystalline photoelectric conversion unit, when a high energy density laser beam is irradiated to form a back electrode separation groove, the transparent electrode layer is thermally damaged. Since it can be suppressed, the decrease in conversion efficiency per light receiving area due to the integration of the integrated thin film solar cell is minimized.

JP 2001-267613 A

  However, when using a method of irradiating a scribing laser beam as a method for forming the back electrode separation groove, the back electrode separation groove is formed by blowing a predetermined region of the back electrode layer simultaneously with a predetermined region of the photoelectric conversion unit layer. When doing so, not only the transparent electrode layer exposed in the area | region of the back surface electrode separation groove | channel but the thermal damage was given also to the edge part of the photoelectric conversion unit layer. Thus, the part which received heat damage became a factor which reduces conversion efficiency.

  Therefore, according to the embodiment of the present invention, a method for manufacturing an integrated photoelectric conversion device capable of improving the conversion efficiency is provided.

  The manufacturing method of the integrated photoelectric conversion device according to the embodiment of the present invention includes a first step of irradiating a transparent conductive film formed on a translucent substrate with a laser beam to form an element isolation groove in the transparent conductive film. A second step of forming a photoelectric conversion layer on the element isolation groove and the first transparent conductive film, a third step of irradiating a laser beam to form a separation groove for connection in the photoelectric conversion layer, and a connection A fourth step of sequentially forming a back electrode and a conductive protective film on the isolation trench and the photoelectric conversion layer, and forming an element dividing groove in the photoelectric conversion layer, the back electrode and the conductive protective film by irradiating a laser beam In the fifth step, the hydrogen concentration in the film is compensated by plasma treatment using a gas containing hydrogen atoms for a part of the photoelectric conversion layer, the back electrode, and the end face side of the conductive protective film through the element dividing groove. 6 steps.

  Preferably, the gas containing a hydrogen atom contains at least H.

Preferably, the gas containing a hydrogen atom contains at least CH ₄ .

Preferably, the gas containing a hydrogen atom contains at least C ₂ H ₆ .

  Preferably, the pressure when performing the hydrogen plasma treatment is 1 Pa or more and 100 Pa or less.

  Preferably, the treatment time when performing the hydrogen plasma treatment is 3 minutes or more and 10 minutes or less.

  In the manufacturing method of the integrated photoelectric conversion device according to the embodiment of the present invention, after the element dividing grooves are formed, the photoelectric conversion layer, the back electrode, and the end surfaces of the conductive protective film are formed by plasma treatment using a gas containing hydrogen atoms. Increase the hydrogen concentration in part of the film on the side. As a result, it is possible to optimize the hydrogen concentration in the film which has been reduced due to thermal damage given to the photoelectric conversion layer when the element dividing grooves are formed, and the current-voltage characteristics of the photoelectric conversion device are improved.

  Therefore, the conversion efficiency of the integrated photoelectric conversion device can be improved.

It is sectional drawing of the integrated photoelectric conversion apparatus in embodiment of this invention. It is sectional drawing of the photoelectric converting layer shown in FIG. FIG. 3 is a first process diagram showing a manufacturing method for manufacturing the integrated photoelectric conversion device shown in FIG. 1. FIG. 6 is a second process diagram illustrating a manufacturing method for manufacturing the integrated photoelectric conversion device illustrated in FIG. 1. FIG. 6 is a third process diagram illustrating a manufacturing method for manufacturing the integrated photoelectric conversion device illustrated in FIG. 1. It is process drawing which shows the detailed process of the process (c) shown in FIG.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  In this specification, the term “amorphous” is used as a synonym for “amorphous” commonly used in the art. Moreover, the term “microcrystal” includes not only a state substantially consisting of only a crystalline phase but also a state in which a crystalline phase and an amorphous phase are mixed as commonly used in the art.

For example, in the Raman scattering spectrum, if even a slight peak near 520 cm ⁻¹ due to a silicon-silicon bond in crystalline silicon is detected, it is considered that “microcrystalline silicon” exists. Also uses the term “microcrystalline silicon” in a similar sense.

  In this specification, “microcrystalline silicon germanium” refers to silicon germanium in the above-described microcrystalline state. That is, the microcrystalline silicon germanium includes not only a state substantially consisting of only a crystalline phase but also an amorphous silicon germanium phase and a crystalline silicon germanium phase.

  In microcrystalline silicon germanium, it is known that the unit cell size of the crystal varies in the range from the unit cell size of crystalline silicon to the unit cell size of crystalline germanium in proportion to the increase in germanium concentration. This means that the ratio of silicon-germanium bonds in the unit cell existing in the volume to be measured increases as the germanium concentration increases.

  Therefore, for example, the presence of the crystalline silicon germanium phase can be detected by determining the size of the unit cell using the X-ray diffraction method. In addition, the presence of a microcrystalline silicon germanium phase can be detected by observing a peak due to crystalline silicon germanium in the Raman scattering spectrum or by changing the position of the peak due to silicon-silicon in crystalline silicon. .

Therefore, in this specification,
(A) The presence of silicon and germanium is confirmed by secondary ion mass spectrometry. (B) The unit cell size determined from the (220) diffraction peak angle in the X-ray diffraction method is the unit cell size (5.43) of crystalline silicon. (C) In the Raman scattering spectrum, a peak due to silicon-silicon of crystalline silicon is observed. (D) Silicon-silicon has a peak that is larger than the unit cell size of crystal germanium (5.67 angstrom). The peak due to Raman shift is shifted to a lower frequency side than the Raman shift position of crystalline silicon not containing germanium. (E) A peak around 400 cm ⁻¹ due to crystalline silicon germanium is observed. For items, at least items (A), (B) When (C) is satisfied simultaneously, or when items (A), (C), (D) are satisfied simultaneously, or at least when items (A), (C), (E) are satisfied simultaneously, the crystalline silicon germanium phase is It is considered to be present and is considered to be crystalline silicon germanium.

  Note that it is difficult to observe the peak due to crystalline silicon germanium when the germanium concentration is relatively low. Therefore, the above items (A), (B), (C), and (D) may be used as means for determining the presence or absence of crystalline silicon germanium.

  Further, in this specification, “amorphous silicon” and “microcrystalline silicon” include “hydrogenated amorphous silicon” and “hydrogenated microcrystalline silicon”, which are generally used in the art, respectively.

  In this specification, amorphous silicon is expressed as “a-Si”. This notation actually means that hydrogen (H) atoms are included. Amorphous silicon containing carbon (C) atoms (a-Si: C), amorphous silicon containing nitrogen (N) atoms (a-Si: N), amorphous silicon containing C atoms and N atoms (a-Si: C: N), amorphous silicon germanium (a-SiGe), amorphous germanium (a-Ge), microcrystalline silicon containing C atoms (μc-Si: C), microcrystalline silicon containing N atoms (μc-Si: N), Also for microcrystalline silicon containing C and N atoms (μc-Si: C: N), microcrystalline silicon (μc-Si), microcrystalline silicon germanium (μc-SiGe), and microcrystalline germanium (μc-Ge) Similarly, it means that an H atom is contained.

  FIG. 1 is a cross-sectional view of an integrated photoelectric conversion device according to an embodiment of the present invention. An integrated photoelectric conversion device 10 according to an embodiment of the present invention includes a translucent substrate 1, transparent conductive films 21 to 2n (n is an integer of 2 or more), photoelectric conversion layers 31 to 3n, and a back electrode 41. To 4n and conductive protective films 51 to 5n.

  The transparent conductive films 21 to 2n are arranged on the main surface of the translucent substrate 1 at desired intervals via the element isolation grooves 61 to 6n-1.

  The photoelectric conversion layer 31 is disposed so as to cover the transparent conductive film 21 and the element isolation trench 61. The photoelectric conversion layer 32 is disposed so as to cover the transparent conductive film 22 and the element isolation trench 62. Hereinafter, similarly, the photoelectric conversion layer 3n-1 is disposed so as to cover the transparent conductive film 2n-1 and the element isolation groove 6n-1, and the photoelectric conversion layer 3n is disposed so as to cover the transparent conductive film 2n. The Each of the photoelectric conversion layers 31 to 3n has at least one pin structure. Each of the photoelectric conversion layers 31 to 3n is mainly formed by a CVD (Chemical Vapor Deposition) method. As the CVD method, an atmospheric pressure CVD method, a low pressure CVD method, a plasma CVD method, a thermal CVD method, a hot wire CVD method, and an MOCVD method can be used.

  The back electrode 41 is disposed so as to cover the photoelectric conversion layer 31 and the connection separation groove 71. The back electrode 42 is disposed so as to cover the photoelectric conversion layer 32 and the connection separation groove 72. Hereinafter, similarly, the back electrode 4n-1 is disposed so as to cover the photoelectric conversion layer 3n-1 and the connection separation groove 7n-1, and the back electrode 4n is disposed so as to cover the photoelectric conversion layer 3n. .

  As a result, the photoelectric conversion layers 31 to 3n are arranged in the in-plane direction of the translucent substrate 1 via the connection separation grooves 71 to 7n-1.

  The conductive protective films 51 to 5n are disposed so as to cover the back electrodes 41 to 4n, respectively.

  The photoelectric conversion layers 31 to 3n, the back electrodes 41 to 4n, and the conductive protective films 51 to 5n are separated by the element dividing grooves 81 to 8n-1. Accordingly, the photoelectric conversion layers 31 to 3n, the back electrodes 41 to 4n, and the conductive protective films 51 to 5n are arranged in the in-plane direction of the translucent substrate 1 via the element dividing grooves 81 to 8n-1.

  The photoelectric conversion layer 31 is in contact with the transparent conductive film 21, the back electrode 41 is in contact with the photoelectric conversion layer 31 and the transparent conductive film 22, the photoelectric conversion layer 32 is in contact with the transparent conductive film 22, and the back electrode 42 is photoelectric. The conversion layer 32 and the transparent conductive film 23 are in contact with each other. Hereinafter, similarly, the photoelectric conversion layer 3n-1 is in contact with the transparent conductive film 2n-1, the back electrode 4n-1 is in contact with the photoelectric conversion layer 3n-1 and the transparent conductive film 2n, and the photoelectric conversion layer 3n is The back electrode 4n is in contact with the photoelectric conversion layer 3n.

  As a result, the photoelectric conversion layers 31 to 3n are connected in series between the transparent conductive film 21 and the back electrode 4n via the transparent conductive films 22 to 2n and the back electrodes 41 to 4n-1.

  Each of the back electrodes 41 to 4n includes a transparent conductive film 2 and an electrode 3. In the back electrodes 41 to 4n-1, the transparent conductive film 2 is disposed so as to cover the photoelectric conversion layers 31 to 3n-1 and the connection separation grooves 71 to 7n-1, respectively. The electrode 3 is disposed so as to cover the transparent conductive film 2.

  The translucent substrate 1 is made of, for example, a glass, polyimide, polyvinyl or other heat-resistant translucent resin plate, or a laminate of glass and the like, and generally has high light transmissivity and photoelectric conversion. It consists of what can structurally support the entire device. Moreover, the surface of the transparent conductive film 21 on the side of the transparent conductive films 21 to 2n may be covered with a metal film, a transparent conductive film, an insulating film, or the like.

Each of the transparent conductive films 21 to 2n is made of a transparent conductive material, for example, a single layer or a plurality of transparent conductive films such as ITO (Indium Tin Oxide), tin oxide (SnO ₂ ), and zinc oxide (ZnO). Consists of layers.

  Since each of the transparent conductive films 21 to 2n plays a role as an electrode, it is preferable that the electrical conductivity is high, even if the electrical conductivity is improved by adding a small amount of impurities. Good.

  And each of the transparent conductive films 21-2n is formed using any methods, such as sputtering method, CVD method, electron beam vapor deposition method, sol gel method, spray method, and electrodeposition method.

  Moreover, it is preferable that each surface (surface by the side of the photoelectric converting layers 31-3n) of the transparent conductive films 21-2n is uneven | corrugated shape. This uneven shape can scatter and refract the incident light incident from the translucent substrate 1 to extend the optical path length, so that the light confinement effect in the photoelectric conversion layers 31 to 3n is increased and the short-circuit current can be improved. .

  As a method of making the surface of the transparent conductive films 21 to 2n uneven, a method of temporarily depositing the transparent conductive film on the translucent substrate 1 and then making the unevenness by mechanical processing such as etching and sandblasting. , A method using irregularities formed by crystal growth of the film material when forming the transparent conductive films 21 to 2n, a method utilizing regular irregularities formed because the crystal growth surface is oriented, etc. Is used.

  In addition, by depositing a zinc oxide layer on the transparent conductive films 21 to 2n by a sputtering method, the tin oxide constituting the transparent conductive films 21 to 2n is damaged by plasma when the photoelectric conversion layers 31 to 3n are formed later. It can be prevented from receiving.

  The photoelectric conversion layers 31 to 3n are mainly made of amorphous silicon or microcrystalline silicon.

  The transparent conductive film 2 is made of the same material as the transparent conductive films 21 to 2n, and is formed by the same method as the method for forming the transparent conductive films 21 to 2n. And the film thickness of the transparent conductive film 2 is 20-3000 nm. If the film thickness is too thick, the amount of light reflected by the electrode 3 and returning to the photoelectric conversion layers 31 to 3n decreases due to light absorption in the transparent conductive film 2, and if the film thickness is too thin, the sheet resistance increases. This is because the current generated by the photoelectric conversion layers 31 to 3n cannot be collected efficiently.

  The transparent conductive film 2 improves the light confinement effect and light reflectivity for incident light, and suppresses diffusion of elements contained in the electrode 3 into the photoelectric conversion layers 31 to 3n.

  The electrode 3 is composed of at least one conductive layer, and is preferably made of a material having a high light reflectance and a high conductivity. More specifically, the electrode 3 is made of silver (Ag), aluminum (Al), titanium (Ti), palladium (Pd), and alloys thereof.

  The electrode 3 is formed by a CVD method, a sputtering method, a vacuum evaporation method, an electron beam evaporation method, a spray method, a screen printing method, or the like.

  And the electrode 3 reflects the light which was not absorbed by the photoelectric converting layers 31-3n, and returns light to the photoelectric converting layers 31-3n again.

  The thickness of the electrode 3 is preferably in a range that ensures sufficient light reflectance and does not hinder the formation of the element dividing grooves 81 to 8n−1, and is, for example, 100 to 400 nm.

Conductive protection film 51~5n generally made of a material having a hydrogen plasma resistance, for _example, made of SnO 2, ITO and ZnO, and the like. Among these, ZnO is particularly preferable because it has a relatively high hydrogen plasma resistance. This is because, after the element dividing grooves 81 to 8n-1 were formed, the hydrogen concentration decreased as a result of thermal damage among the ends of the photoelectric conversion layers 31 to 3n on the element dividing grooves 81 to 8n-1 side. This is because the back electrodes 41 to 4n can be protected from physical and chemical damage when increasing the hydrogen concentration in the region.

  The film thickness of the conductive protective films 51 to 5n is not particularly limited, but may be any film thickness that can withstand the hydrogen plasma conditions, for example, 20 to 200 nm.

  FIG. 2 is a cross-sectional view of the photoelectric conversion layer 31 shown in FIG. With reference to FIG. 2, the photoelectric conversion layer 31 includes a p-type semiconductor layer 311, an i-type semiconductor layer 312, and an n-type semiconductor layer 313.

  The p-type semiconductor layer 311, the i-type semiconductor layer 312 and the n-type semiconductor layer 313 are formed of the transparent conductive film 21 in the order of the p-type semiconductor layer 311, the i-type semiconductor layer 312 and the n-type semiconductor layer 313 from the translucent substrate 1 side. And laminated on the element isolation trench 61. Thus, the photoelectric conversion layer 31 has a pin structure.

  The p-type semiconductor layer 311 is a silicon layer doped with a p-type conductivity dopant. The p-type dopant is made of, for example, boron (B), aluminum (Al), gallium (Ga), or the like.

  More specifically, the p-type semiconductor layer 311 includes p-type amorphous silicon (p-type a-Si), p-type amorphous silicon containing C atoms (p-type a-Si: C), and p-type amorphous containing N atoms. Silicon (p-type a-Si: N), p-type amorphous silicon containing C and N atoms (p-type a-Si: C: N), p-type microcrystalline silicon (p-type μc-Si), C atoms P-type microcrystalline silicon containing (p-type μc-Si: C), p-type microcrystalline silicon containing N atoms (p-type μc-Si: N), and p-type microcrystalline containing both C and N atoms It is made of any one of silicon (p-type μc-Si: C: N).

  When the p-type semiconductor layer 311 is made of any of p-type μc-Si, p-type μc-Si: C, p-type μc-Si: N, and p-type μc-Si: C: N, that is, a p-type semiconductor layer When 311 includes a crystalline silicon phase, high conductivity is obtained and the series resistance of the photoelectric conversion layer 31 can be reduced, so that the fill factor is improved and high conversion efficiency can be obtained.

  In addition, when the p-type semiconductor layer 311 includes a crystalline silicon phase, the i-type semiconductor layer 312 is excellent as a base layer for crystallization of the i-type semiconductor layer 312. Under the influence of the semiconductor layer 311), the crystal component easily grows, and a high-quality i-type semiconductor layer 312 having a high crystallization rate is obtained. As a result, the short circuit current increases and the conversion efficiency can be improved.

  Accordingly, the p-type semiconductor layer 311 preferably includes a crystalline silicon phase.

  The p-type semiconductor layer 311 is p-type a-Si: C, p-type a-Si: N, p-type a-Si: C: N, p-type μc-Si: C, p-type μc-Si: N, and p-type When it consists of any of μc-Si: C: N, that is, when the p-type semiconductor layer 311 contains a carbon atom and / or a nitrogen atom, the p-type semiconductor layer contains a carbon atom and / or a nitrogen atom. The open circuit voltage of the photoelectric conversion layer 31 is improved and high conversion efficiency can be obtained as compared with the case where there is not. The reason is as follows.

  (1) The optical band gap of the p-type semiconductor layer widens and the diffusion potential at the pin junction increases.

  (2) Interface recombination is reduced by the interface passivation effect of the crystal grain boundary due to the addition of impurities (carbon atoms or nitrogen atoms) and the interface passivation effect of the p-type semiconductor layer / i-type semiconductor layer.

  In addition, when the impurity (carbon atom or nitrogen atom) concentration is low, band discontinuity or mismatch between the p-type semiconductor layer 311 and the i-type semiconductor layer 312 hardly occurs, and the p-type semiconductor layer 311 and the i-type semiconductor layer are not easily generated. There is no need to provide an interface layer or the like between the substrate 312 and the like. As a result, a photoelectric conversion device that is simple, inexpensive, and has high conversion efficiency can be obtained.

  Therefore, it is preferable that the p-type semiconductor layer contains a carbon atom or a nitrogen atom.

  And the film thickness of the p-type semiconductor layer 311 is 5-50 nm, for example, Preferably, it is 10-30 nm.

  The i-type semiconductor layer 312 is made of amorphous silicon or microcrystalline silicon to which no impurity is added. Note that the i-type semiconductor layer 312 may contain a small amount of an impurity element as long as it is a substantially intrinsic semiconductor.

  The i-type semiconductor layer 312 is preferably made of microcrystalline silicon. This is because light conversion can be prevented and high conversion efficiency can be obtained.

  Further, the i-type semiconductor layer 312 may contain amorphous silicon germanium or microcrystalline silicon germanium in order to increase long wavelength sensitivity. In this case, the germanium concentration of the i-type semiconductor layer 312 is preferably 5 to 30 atomic%. If the germanium concentration is less than 5 atomic%, the optical band gap does not decrease so much, so the short circuit current does not increase so much and is not practical. When the germanium concentration exceeds 30 atomic%, the conversion efficiency is increased due to the remarkable effect that the open-circuit voltage of the photoelectric conversion layer 31 decreases as the optical band gap decreases or the crystal grain size becomes too small. Is unfavorable because of lowering.

  And the film thickness of the i-type semiconductor layer 312 is 100-5000 nm, for example, Preferably, it is 200-4000 nm.

  The n-type semiconductor layer 313 is formed of a silicon layer doped with an n-type conductivity dopant. The n-type conductivity type dopant includes, for example, phosphorus (P), nitrogen (N), oxygen (O), and the like.

  More specifically, the n-type semiconductor layer 313 includes n-type a-Si, n-type a-Si: C, n-type a-Si: N, n-type a-Si: C: N, and n-type μc-Si. N-type μc-Si: C, n-type μc-Si: N, and n-type μc-Si: C: N.

  When the n-type semiconductor layer 313 is made of any of n-type μc-Si, n-type μc-Si: C, n-type μc-Si: N, and n-type μc-Si: C: N, that is, the n-type semiconductor layer When 313 contains a crystalline silicon phase, high conductivity is obtained and the series resistance of the photoelectric conversion layer 31 can be reduced, so that the fill factor is improved and high conversion efficiency can be obtained.

  Therefore, the n-type semiconductor layer 313 preferably includes a crystalline silicon phase.

  The n-type semiconductor layer 313 is n-type a-Si: C, n-type a-Si: N, n-type a-Si: C: N, n-type μc-Si: C, n-type μc-Si: N, and n-type In the case where it is composed of any one of μc-Si: C: N, that is, when the n-type semiconductor layer 313 contains a carbon atom or a nitrogen atom, compared with the case where the n-type semiconductor layer does not contain a carbon atom or a nitrogen atom. The open circuit voltage of the photoelectric conversion layer 31 is improved, and high conversion efficiency can be obtained. The reason is as follows.

  (1) The optical band gap of the n-type semiconductor layer widens and the diffusion potential at the pin junction increases.

  (2) Interface recombination is reduced by the interface passivation effect of the crystal grain boundary due to the addition of nitrogen atoms and the interface passivation effect of the i-type semiconductor layer / n-type semiconductor layer.

  And the film thickness of the n-type semiconductor layer 313 is 5-100 nm, for example, Preferably, it is 10-30 nm.

  Note that in the case where the p-type semiconductor layer 311 and the n-type semiconductor layer 313 contain carbon atoms, it is assumed that a crystal phase of silicon carbide is not substantially contained. Therefore, p-type μc-Si: C, n-type μc-Si: C, p-type μc-Si: C: N, and n-type μc-Si: C: N substantially contain the crystalline phase of silicon carbide. Not.

  This state is confirmed by, for example, that when a Raman scattering spectrum of microcrystalline silicon containing a carbon atom is observed, a peak due to a silicon-carbon bond constituting the silicon carbide crystal is not substantially observed. This state is confirmed by the fact that a diffraction peak due to the silicon carbide crystal structure is not substantially detected in X-ray diffraction.

  Each of the photoelectric conversion layers 32 to 3n also has the same configuration as the photoelectric conversion layer 31 illustrated in FIG.

The material gas used when forming the photoelectric conversion layers 31 to 3n is not particularly limited as long as it is a gas containing silicon atoms such as a silane (SiH ₄ ) gas and a disilane (Si ₂ H ₆ ) gas. Specifically, SiH ₄ gas is often used.

In addition, as a diluent gas used together with a gas containing silicon atoms, hydrogen (H ₂ ) gas, nitrogen (N ₂ ) gas, argon (Ar) gas, and helium (He) gas can be used. In the case of forming microcrystalline silicon, H ₂ gas is often used.

When forming the p-type semiconductor layer and the n-type semiconductor layer, a doping gas is used together with a gas containing silicon atoms and a dilution gas. The doping gas is not particularly limited as long as it includes an element that determines the target conductivity type. Generally, when the element that determines the p-type conductivity type is boron (B), diborane (B ₂ H ₆ ) gas is used as a doping gas, and phosphine (PH ₃ ) gas is generally used as a doping gas when the element that determines the n-type conductivity is phosphorus (P).

  When the photoelectric conversion layers 31 to 3n are formed by the plasma CVD method, the abundance ratio of the amorphous phase and the crystalline phase is controlled by controlling the substrate temperature, the pressure in the reaction chamber, the gas flow rate, and the input power to the plasma. be able to.

  The formation method of the element isolation grooves 61 to 6n-1, the connection isolation grooves 71 to 7n-1, and the element division grooves 81 to 8n-1 is not particularly limited as long as the target material can be processed. Further, a wet etching method using a chemical solution, a reactive ion etching (RIE) method, and a dry etching method such as a laser scribing method may be used.

  Among these, a laser scribing method that can be processed by a dry method without using a vacuum apparatus is preferably used. In the laser scribing method, the laser is generally incident from the substrate side.

  The laser wavelength used in the laser scribing method is YAG 1064 nm (hereinafter referred to as “IR laser”) and SHG532 nm (hereinafter referred to as “SHG laser”) which is the second harmonic of the YAG laser.

  The IR laser is absorbed by the transparent conductive films 21 to 2n. As a result, the transparent conductive films 21 to 2n generate heat and ablation occurs, and a part of the transparent conductive films 21 to 2n is removed. Therefore, an IR laser is used in the step of forming the element isolation grooves 61 to 6n-1.

  On the other hand, the SHG laser is hardly absorbed by the transparent conductive films 21 to 2n, and most of the SHG laser is absorbed by the photoelectric conversion layers 31 to 3n. As a result, when the photoelectric conversion layers 31 to 3n generate heat, ablation occurs, and a part of the photoelectric conversion layers 31 to 3n and a layer deposited on a part of the photoelectric conversion layers 31 to 3n are removed. Therefore, an SHG laser is used in the step of forming the connection separating grooves 71 to 7n-1 and the element dividing grooves 81 to 8n-1.

  In addition, when irradiating IR laser and SHG laser, the laser is often irradiated in a pulse shape at an appropriate frequency, and the frequency is typically 5 kHz to 30 kHz or the like. The processing speed and the like are adjusted as appropriate so that the trace from which the film is removed by laser irradiation continuously forms grooves. As the processing speed, 50 mm / second to 1000 mm / second is typically used. However, the processing speed is continuous depending on the combination of the frequency when irradiating the pulsed laser, the shape of the processing trace, the width of the processing trace, and the processing speed. Thus, the parameters are selected in combination so that the groove can be formed.

  The output of the laser is determined by the average power in the pulse output state. In the case of the IR laser, an output of about 8 to 15 W is used, and in the case of the SHG laser, an output of about 0.1 to 0.5 W is used. Since the appropriate output varies depending on the volume of the processing object, the adhesion strength of the processing object, and the processing speed, an appropriate value is selected in consideration of the processing state.

  In the embodiment of the present invention, after the element dividing grooves 81 to 8n-1 are formed, hydrogen plasma treatment is performed. As a result, the reduced hydrogen concentration in the film can be optimized as a result of thermal damage that has occurred at the ends of the photoelectric conversion layers 31 to 3n during the formation of the element dividing grooves 81 to 8n-1.

  When performing the hydrogen plasma treatment, the apparatus has a configuration in which a parallel plate for applying an electric field from the outside is provided inside the vacuum chamber.

  When an electric field is applied under an appropriate condition while flowing a gas containing hydrogen in the vacuum chamber, various active hydrogen species such as ion species and radical species having energy are generated by plasma discharge. When the generated active hydrogen species reacts with the silicon dangling bond, the silicon dangling bond can be terminated by bonding with the silicon. For the application of an electric field, an RF power source having a frequency of 13.56 MHz is widely used.

For the hydrogen plasma treatment, a gas containing hydrogen such as methane gas and ethane gas is used in addition to hydrogen gas. Of these gases, hydrogen gas is preferable because there is no deposition of carbon deposits and CO ₂ gas that causes global warming is not generated when the unreacted gas is detoxified.

  In the embodiment of the present invention, the end of the photoelectric conversion layers 31 to 3n exposed to the element dividing grooves 81 to 8n-1 is subjected to hydrogen termination treatment. In order to implement this suitably, the pressure may be 1 Pa or more and 100 Pa or less. By setting the pressure within this range, the mean free path of the active species of hydrogen gas or the energy of the active hydrogen species can be increased. As a result, the end portions of the photoelectric conversion layers 31 to 3n can be suitably terminated with hydrogen through the element dividing grooves 81 to 8n-1.

  Moreover, processing time is determined by the grade which terminates the edge part of the photoelectric converting layers 31-3n. That is, when the laser output at the time of forming the element dividing grooves 81 to 8n-1 is increased, the heat-damaged regions are widely distributed at the ends of the photoelectric conversion layers 31 to 3n. preferable.

  On the contrary, when the element dividing grooves 81 to 8n-1 are formed while suppressing the laser output, since a power generation region as a photoelectric conversion device can be widened, a short processing time is preferable in order to shorten the process time.

Further, the treatment time depends on the type and temperature of the gas, but also depends on the concentration of active species in the reaction space, and greatly depends on the input power. Considering the above, the input power is 0.1 W / cm ² or more and 10 W / cm ² or less, and the treatment time is 3 minutes or more and 10 minutes or less.

  3 to 5 are first to third process diagrams showing a manufacturing method for manufacturing the integrated photoelectric conversion device 10 shown in FIG. 1, respectively.

  3 to 5, the light-transmitting substrate 1 and the transparent conductive films 21 to 2n are formed by depositing tin oxide on a blue plate glass (Asahi Glass Co., Ltd., trade name Asahi-U) by a CVD method. It is made of zinc deposited with a thickness of 20 nm by sputtering on tin, the p-type semiconductor layer 311 is made of p-type μc-Si, the i-type semiconductor layer 312 is made of i-type μc-Si, and the n-type semiconductor layer 313 is made of Manufacture of integrated photoelectric conversion device 10 by taking as an example a case where n-type μc-SiN is used, transparent conductive film 2 is made of zinc oxide, electrode 3 is made of silver, and conductive protective films 51 to 5n are made of zinc oxide. A method will be described.

  When the manufacture of the integrated photoelectric conversion device 10 is started, the above-described translucent substrate 1 and the transparent conductive film 20 are prepared (see step (a) in FIG. 3).

  Then, the transparent conductive film 20 is irradiated with laser light from the translucent substrate 1 side by IR laser to form element isolation grooves 61 to 6n-1 in the transparent conductive film 20 (see step (b) in FIG. 3). Thereby, the transparent conductive films 21 to 2n are formed on one main surface of the translucent substrate 1.

  Thereafter, the photoelectric conversion layer 30 is formed on the transparent conductive films 21 to 2n by the plasma CVD method so as to fill the element isolation grooves 61 to 6n-1 (see step (c) in FIG. 3).

  Then, the photoelectric conversion layer 30 is irradiated with laser light from the translucent substrate 1 side by the SHG laser to form connection separation grooves 71 to 7n-1 in the photoelectric conversion layer 30 (see step (d) in FIG. 3). . As a result, photoelectric conversion layers 31 ′ to 3 n ′ are formed on the transparent conductive films 21 to 2 n.

  After the step (d), the transparent conductive film 4 made of zinc oxide is formed on the photoelectric conversion layers 31 ′ to 3n ′ by DC sputtering so as to fill the connection separation grooves 71 to 7n-1 (step of FIG. 3). (See (e)). In this case, sputtering conditions are as follows: the flow rate of argon gas is 200 sccm, the pressure is 0.532 Pa, and the input power is 150 W. The film thickness of the transparent conductive film 4 (= ZnO) is, for example, 80 nm.

  After the step (e), an electrode 5 made of silver is deposited on the transparent conductive film 4 by a DC sputtering method (see step (f) in FIG. 4). In this case, sputtering conditions are as follows: the flow rate of argon gas is 200 sccm, the pressure is 2.66 Pa, and the input power is 300 W. The film thickness of the electrode 5 is 120 nm.

  After the step (f), a conductive protective film 6 made of zinc oxide is formed on the electrode 5 (see step (g) in FIG. 4). In this case, the thickness of the conductive protective film 6 is 80 nm.

  After the step (g), the photoelectric conversion layers 31 ′ to 3 n ′, the transparent conductive film 4, the electrode 5, and the conductive protective film 6 are irradiated with laser light from the translucent substrate 1 side by the SHG laser. Element division grooves 81 to 8n-1 are formed in '~ 3n', transparent conductive film 4, electrode 5 and conductive protective film 6 (see step (h) in FIG. 4). As a result, photoelectric conversion layers 31 ′, 32 ″ to 3 n ″, backside electrodes 41 ′ to 4 n ′, and conductive protective films 51 ′ to 5 n ′ are formed.

After the step (h), the photoelectric conversion layers 31 ′, 32 ″ to 3n ″, the back electrodes 41 ′ to 4n ′, and the conductive protective films 51 ′ to 5n are passed through the element dividing grooves 81 to 8n-1 by hydrogen plasma treatment. The end of 'is terminated with hydrogen (see step (i) in Fig. 5). In this case, H ₂ gas was used as the hydrogen plasma gas, the treatment time was 3 minutes, and 0.6 W / cm ² high frequency power having a frequency of 13.56 MHz was used as the input power. Thereby, the integrated photoelectric conversion device 10 is completed.

  FIG. 6 is a process diagram showing a detailed process of the process (c) shown in FIG.

After the step (b) shown in FIG. 3, a p-type semiconductor layer 301 is deposited on the transparent conductive films 21 to 2n by plasma CVD so as to fill the element isolation grooves 61 to 6n-1 (step (c) in FIG. -1)). In this case, a mixed gas composed of SiH ₄ gas, H ₂ gas, and B ₂ H ₆ gas was used as the source gas. The flow rate ratio of H ₂ gas to SiH ₄ gas was 150 times, and the flow rate ratio of B ₂ H ₆ gas to SiH ₄ gas was 0.003 times. The substrate temperature is 180 ° C. Thereby, the p-type semiconductor layer 301 made of p-type μc-Si is formed. The film thickness of the p-type semiconductor layer 301 is 20 nm.

After the step (c-1), the i-type semiconductor layer 302 is deposited on the p-type semiconductor layer 301 by a plasma CVD method (see step (c-2) in FIG. 6). In this case, a mixed gas composed of SiH ₄ gas and H ₂ gas was used as the source gas. The flow rate ratio of H ₂ gas to SiH ₄ gas was 80 times. The substrate temperature is 180 ° C. Thereby, an i-type semiconductor layer 302 made of i-type μc-Si is formed. The film thickness of the i-type semiconductor layer 302 is 1850 nm.

After the step (c-2), an n-type semiconductor layer 303 is deposited on the i-type semiconductor layer 302 by a plasma CVD method (see step (c-3) in FIG. 6). In this case, a mixed gas composed of SiH ₄ gas, H ₂ gas and PH ₃ gas was used as the source gas. The flow rate ratio of H ₂ gas to SiH ₄ gas was set to 100 times, and the flow rate ratio of PH ₃ gas to SiH ₄ gas was set to 0.03 times. The substrate temperature is 180 ° C. Thereby, an n-type semiconductor layer 303 made of n-type μc-Si is formed. The film thickness of the n-type semiconductor layer 303 is 20 nm.

  The photoelectric conversion layer 30 is formed by completion | finish of a process (c-3), and the process (c) shown in FIG. 3 is complete | finished.

  As described above, after the element dividing grooves 81 to 8n−1 are formed, the end portions of the photoelectric conversion layers 31 ′ and 32 ″ to 3n ″ are hydrogen-terminated by hydrogen plasma treatment via the element dividing grooves 81 to 8n−1. Thus, the integrated photoelectric conversion device 10 is manufactured.

  As a result, the hydrogen concentration in the region where the hydrogen concentration has decreased as a result of thermal damage when forming the element dividing grooves 81 to 8n-1 can be optimized. As a result, the current-voltage characteristics of the photoelectric conversion layers 31 to 3n are improved, and the conversion efficiency of the integrated photoelectric conversion device 10 can be improved.

  In the steps (a) to (j) (including steps (c-1) to (c-3)) shown in FIGS. 3 to 6, the photoelectric conversion layers 31 to 3n have a single pin structure. The manufacturing method of the integrated photoelectric conversion device 10 has been described. However, when the photoelectric conversion layers 31 to 3n have two or more pin structures, in the step (c) shown in FIG. 3, two or more pin structures are transparent. The layers are sequentially stacked on the conductive films 21 to 2n. In this case, steps (c-1) to (c-3) shown in FIG. 6 are repeatedly executed twice or more.

  When each of the photoelectric conversion layers 31 to 3n has two pin structures, the pin structure disposed on the translucent substrate 1 side is referred to as a top cell, and the pin structure disposed on the back electrodes 41 to 4n side is referred to as a bottom cell. Call.

  The top cell is made of, for example, amorphous silicon, and the bottom cell is made of, for example, microcrystalline silicon or amorphous silicon germanium.

  In addition, when each of the photoelectric conversion layers 31 to 3n has three pin structures, the pin structure disposed on the translucent substrate 1 side is referred to as a top cell, and the pin structure disposed on the back electrodes 41 to 4n side. It is called a bottom cell, and the pin structure arranged between the top cell and the bottom cell is called a middle cell.

  The top cell is made of, for example, amorphous silicon, amorphous silicon containing C atoms, or amorphous silicon containing N atoms, the middle cell is made of, for example, amorphous silicon, amorphous silicon germanium, or microcrystalline silicon, and the bottom cell is made of For example, it is made of amorphous silicon, microcrystalline silicon, or microcrystalline silicon germanium.

  Accordingly, when each of the photoelectric conversion layers 31 to 3n has two or more pin structures, the two or more pin structures have a small optical band gap from the translucent substrate 1 side to the back electrodes 41 to 4n side. Is selected.

Example 1
An integrated photoelectric conversion device was manufactured according to steps (a) to (i) (including steps (c-1) to (c-3)) shown in FIGS. Then, a manufacturing the integrated photoelectric conversion device, AM 1.5, current of the cell having an area of 1 cm ² under the conditions of an irradiation intensity 100 mW / cm ² - voltage characteristics were measured.

As a result, the short-circuit current density was 21.8 mA / cm ² , the open circuit voltage was 0.520 V, the fill factor was 0.715, and the conversion efficiency was 8.11%.

(Comparative Example 1)
In Example 1, an integrated photoelectric conversion device was produced in the same manner as in Example 1 except that the end portions of the photoelectric conversion layers 31 ′, 32 ″ to 3n ″ were not hydrogen-terminated by hydrogen plasma treatment. Then, a manufacturing the integrated photoelectric conversion device, AM 1.5, current of the cell having an area of 1 cm ² under the conditions of an irradiation intensity 100 mW / cm ² - voltage characteristics were measured.

As a result, the short-circuit current density was 21.8 mA / cm ² , the open circuit voltage was 0.510 V, the fill factor was 0.703, and the conversion efficiency was 7.81%.

  According to the comparison between Example 1 and Comparative Example 1, the curve factor and the open-circuit voltage were mainly improved in Example 1 in which the hydrogen plasma treatment was performed after the formation of the element dividing grooves 81 to 8n−1. High conversion efficiency was obtained.

  It has been empirically known that conversion efficiency tends to decrease when the laser output is intentionally increased during the formation of the element dividing grooves 81 to 8n-1, and this is found on the end face of the photoelectric conversion layer. This is thought to be due to damage. That is, after the element dividing grooves 81 to 8n−1 are formed, the conversion efficiency remains low because the end face of the photoelectric conversion layer is damaged. Specifically, since these regions are heated by thermal laser ablation, hydrogen is released from the film, and the hydrogen concentration is lowered.

  Therefore, as in the manufacturing method according to the embodiment of the present invention, after the element dividing grooves 81 to 8n−1 are formed, the damaged portions of the photoelectric conversion layers 31 ′, 32 ″ to 3n ″ are hydrogenated by hydrogen plasma treatment. Conversion efficiency was improved by optimizing the concentration. Therefore, according to the manufacturing method according to the embodiment of the present invention, the damage at the time of forming the element dividing grooves 81 to 8n-1 can be repaired, and the conversion efficiency of the integrated photoelectric conversion device 10 can be improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a manufacturing method of an integrated photoelectric conversion device.

  DESCRIPTION OF SYMBOLS 1 Translucent board | substrate, 2,4,20-2n transparent conductive film, 3,5 electrode, 10 integrated photoelectric conversion apparatus, 30-3n photoelectric conversion layer, 41-4n back electrode, 51-5n conductive protective film, 61 to 6n-1 element isolation groove, 71 to 7n-1 connection isolation groove, 81 to 8n-1 element division groove, 301, 311 p-type semiconductor layer, 302, 312 i-type semiconductor layer, 303, 313 n-type semiconductor layer.

Claims (5)

A method for manufacturing an integrated photoelectric conversion device, comprising:
A first step of irradiating a transparent conductive film formed on a light-transmitting substrate with a laser beam to form an element isolation groove in the transparent conductive film;
A second step of forming a photoelectric conversion layer on the element isolation trench and the first transparent conductive film;
A third step of irradiating a laser beam to form a separation groove for connection in the photoelectric conversion layer;
A fourth step of sequentially forming a back electrode and a conductive protective film on the connection separation groove and the photoelectric conversion layer;
A fifth step of irradiating a laser beam to form an element dividing groove in the photoelectric conversion layer, the back electrode, and the conductive protective film;
A sixth step of performing a hydrogen plasma treatment using a gas containing hydrogen atoms on the photoelectric conversion layer, the back electrode, and a part of the end face side of the conductive protective film through the element dividing groove. A method for manufacturing a photoelectric conversion device.   The method for manufacturing an integrated photoelectric conversion device according to claim 1, wherein the gas containing hydrogen atoms contains at least H. The method for manufacturing an integrated photoelectric conversion device according to claim 1, wherein the gas containing hydrogen atoms contains at least CH ₄ . The method for manufacturing an integrated photoelectric conversion device according to claim 1, wherein the gas containing hydrogen atoms includes at least C ₂ H ₆ .   5. The method for manufacturing an integrated photoelectric conversion device according to claim 1, wherein a pressure when performing the hydrogen plasma treatment is 1 Pa or more and 100 Pa or less.

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