JP2819056B2 - Method and apparatus for forming deposited film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mass-produced method and apparatus suitable for forming a silicon-containing deposited film, particularly, a photovoltaic element.

[Description of the Related Art] For example, a functional deposition film such as an amorphous silicon film (hereinafter abbreviated as a-Si) is formed by a vacuum deposition method, a plasma CVD method, a CVD method, a reactive sputtering method, an ion plating method, or the like. Methods, photo-CVD methods and the like have been tried, and in general, plasma CVD methods are widely used and commercialized.

However, in general, deposited films formed by these deposition film forming methods are not suitable in terms of electrical and optical characteristics, fatigue characteristics in repeated use or use environment characteristics, and productivity and mass productivity including uniformity and reproducibility. There is room for further improving the overall characteristics. Among them, electrical, optical, photoconductive or from the viewpoint of developing a deposited film that can sufficiently satisfy each of the mechanical properties, at present it is best to form by a plasma CVD method, Depending on the application of the deposited film, the plasma CVD method must be used to increase the uniformity of the film quality while increasing the area and uniforming the film thickness and to achieve reproducible mass production by high-speed film formation. These have been pointed out as problems to be improved in the future in the formation of a deposited film. Therefore, as a means for solving these problems, a precursor (B) which is a raw material for forming a deposited film generated in an activation space and is used as a raw material for forming a deposited film in a film forming space for forming a deposited film on a substrate,
A deposition film formation method has been proposed in which a deposition film is formed on the substrate by introducing an active species (A) generated in an activation space and interacting with the precursor.

Note that the “precursor (B)” can be a raw material of a deposited film to be formed, but refers to a material that can or cannot hardly form a deposited film in the same energy state.
The “active species (A)” means a chemical interaction with the precursor (B), for example, giving energy to the precursor (B) or chemically reacting with the precursor (B). And serves to bring the precursor (B) into a state in which a deposited film can be formed. Therefore, the active species (A) may include a component constituting a component constituting a deposited film to be formed, or may not include such a component.

This method of forming a deposited film is also suitable for manufacturing a photovoltaic element using a high-quality and inexpensive a-Si. In particular, by assembling a roll-to-roll mass-production apparatus using a roll-shaped base material, , A significant increase in productivity is expected.

On the other hand, among photovoltaic elements, research and development for improving the performance of solar cells using amorphous materials containing Group IV elements of the periodic table is remarkable, effectively absorbing the entire spectrum of sunlight, and In order to obtain photoelectric conversion efficiency, a material having high short-wavelength sensitivity, such as amorphous silicon carbide (hereinafter abbreviated as a-SiC), or a material having high long-wavelength sensitivity, such as amorphous silicon germanium (hereinafter a).
-SiGe. ) Have been developed. At present, great results are being achieved with a triple configuration in which solar cells made of these materials are stacked.

Also, in a single-layer solar cell, the open-circuit voltage V _0C is increased by having a larger band gap (hereinafter abbreviated as Eg) on the light incident side and having an inclined band profile that becomes smaller in the film thickness direction. It is possible to improve the conversion efficiency. This band profile is shown in FIG.

In particular, a band profile has been devised in which holes having low mobility are promoted in the I-layer, particularly in intrinsic a-Si, a-SiGe and a-SiC films. That is, if the band profile shown in FIG. 7 (B) is formed, the drift of the photo-generated holes in the forward direction is promoted, and the FF of the solar cell is improved. Further, a buffer layer having the same effect as the band profile shown in FIG. 7 (A) is provided on the light receiving surface side in the band profile of FIG. 7 (B).
With the band profile shown in the figure, a high open-circuit voltage and a high FF can be obtained. Thus the seventh
(C) The band profile shown in the figure is made of an amorphous material having a different band gap, for example, a-SiGe.
By forming and laminating with an a-SiC film, a photovoltaic element such as a solar cell with extremely high efficiency can be produced.

However, in order to mass-produce a high-performance photovoltaic element having such a tilted band profile, it is necessary to design a mass-production method and an apparatus with as simple a device configuration as possible and with a small number of items to be managed. is there.

It is thought that mass production of photovoltaic devices with these inclined band profiles on a roll-to-roll basis can be dealt with by installing a plurality of deposition chambers with different Eg steps in series. In addition to the fact that the best graded band profile cannot be obtained with the mold, the increase in the number of deposition chambers leads to an increase in equipment costs, operation costs, and management items, thereby increasing the manufacturing cost of the photovoltaic device. Had.

[Object of the invention]

An object of the present invention is to provide a deposition film forming method suitable for producing a high-performance photovoltaic element using a tilted band profile in a roll-to-roll mass production apparatus and an apparatus therefor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for forming a deposited film capable of stably mass-producing a high-performance photovoltaic element using an inclined band profile and reducing the production cost. It is in.

[Configuration of the invention]

The present invention includes an active species (A) obtained by activating a gas containing at least hydrogen, at least silicon and one or more elements (b) selected from Group IV of the periodic table other than silicon, and a halogen. The flow (AB) obtained by mixing the precursor (B) obtained by activating the source gas is guided to the substrate moving in the direction along the surface, and a functional deposition film is formed on the substrate. In the method of forming a deposited film, the ratio of the number of atoms of the element (b) to the number of silicon atoms contained in the deposited film obtained on the substrate gradually decreases in the direction of progress of the flow (AB). This effect will be described below.

The present invention includes a deposited film forming method and a deposited film forming apparatus described below.

The method of forming a deposited film according to the present invention is characterized in that the active species (A) obtained by activating a gas containing at least hydrogen, at least silicon and at least one element selected from Group IV of the periodic table other than silicon, and halogen A stream (AB) obtained by mixing the precursor (B) obtained by activating the raw material gas containing, to a substrate moving in a direction along the surface thereof,
In a deposition film forming method for forming a functional deposition film having an inclined band profile such that a band gap is increased on the substrate side on the substrate side, the active species (A) and the precursor (B) are formed on the substrate. On the downstream side in the moving direction, each of the introduction pipes is introduced into the deposition space at an angle with respect to the substrate from the different introduction pipe toward the deposition space on the upstream side in the moving direction of the substrate and toward the deposition space, and the flow (AB) flows to the surface of the substrate. After flowing in the deposition space surrounded by the wall provided in the direction along and the surface of the substrate, the air is exhausted from the upstream side in the moving direction of the substrate.

The apparatus for forming a deposited film according to the present invention is characterized in that an active species (A) obtained by activating a gas containing at least hydrogen, at least silicon and at least one element selected from Group IV of the periodic table other than silicon, and halogen. A stream (AB) obtained by mixing the precursor (B) obtained by activating the raw material gas containing, to a substrate moving in a direction along the surface thereof,
In a deposition film forming apparatus for forming a functional deposition film having an inclined band profile such that a band cap becomes larger on the substrate side on the substrate side, the active species (A) and the precursor (B) are formed on the substrate. A deposition surrounded by a wall provided in a direction along the surface of the substrate so as to be introduced at an angle toward the deposition film forming space on the upstream side in the direction of movement of the substrate on the downstream side in the direction of movement. Each of the active species (A) and the precursor (B) provided at an angle to the moving substrate disposed downstream in the direction of movement of the substrate in the film formation space. After the flow (AB) flows through the wall provided in the direction along the surface of the substrate and the deposition film forming space surrounded by the surface of the substrate, and then flows from the upstream side in the moving direction of the substrate. Exhausted And having an exhaust port provided on the downstream side in the moving direction of the base body of the space so.

 Hereinafter, the operation of the present invention will be described.

FIG. 8 is a top view of the device for explaining the operation of the present invention.

In FIG. 8, reference numeral 1 denotes an introduction pipe for introducing a gas containing at least hydrogen which becomes the active species (A), and 2 denotes at least silicon which becomes the precursor (B) and a group IV in the periodic table other than silicon. This is an introduction pipe through which a source gas containing one or more elements (b) selected from the group consisting of halogen and halogen is passed. Reference numeral 3 denotes a microwave plasma generator for activating a part or all of these gases to generate plasma, thereby generating the active species (A) and the precursor (B). The stream (AB) obtained by mixing these is indicated by the arrow 5. After introducing the stream (AB) onto the substrate 6 maintained at a predetermined temperature, the stream (AB) is evacuated from the vacuum chamber 4 to the outside.

Hydrogen and Ar gas were introduced from the gas introduction tube 1 and SiF ₄ and GeF ₄ gas were introduced from the gas introduction tube 2 under the conditions summarized in Table 1. The microwave effective power was applied to the microwave plasma generator 3 When a predetermined amount is applied, a hydrogen atom corresponding to the active species (A) and a precursor corresponding to the precursor (B) generated from activated SiF ₄ and GeF ₄ are generated, respectively, and the introduction pipe outlet of 2 And an a-SiGe film is deposited on the substrate 6. A # 7059 glass substrate manufactured by Corning Co., Ltd. was placed on the substrate No. 6, and its band gap distribution was determined by Tauc plot in the direction of the flow (AB). Further, an aluminum substrate was placed on the substrate of No. 6, and the distribution of Ge concentration in the film was similarly obtained by XMA in the flow direction of the flow (AB). These are summarized in the graph of FIG.

In FIG. 9, the horizontal axis x is scaled in the direction of the flow (AB), and the vertical axes are Eg and Ge concentration in the film, respectively. From FIG. 9, it can be seen that the Ge temperature of the deposited film obtained on the substrate is about 2 (at) as it proceeds downstream in the direction of the flow (AB).
omic%) to about 40 (atomic%), and Eg also decreases linearly from 1.7 (eV) to 1.4 (eV).

Similarly, an example of forming an a-SiC film will be described. Gas inlet pipe 102
Then, CF ₄ is introduced instead of GeF ₄ , and an a-SiC film is formed on the substrate under the predetermined forming conditions summarized in Table 1. a-SiG
As in the case of the e-film, the distribution of 6 on the substrate was examined with respect to Eg and the C concentration in the film.
It increases linearly from 1.7 (eV) to 2.1 (eV), and the C concentration in the film is about 3 (atomic%) to 20 (atomic).
%) Tended to increase linearly.

The inventors have found that the ratio of the number of atoms of the element (b) to the number of silicon atoms in the deposited film deposited on the substrate gradually increases toward the downstream in the direction of the flow (AB). As a result, it has been found that Eg gradually changes, and by applying this finding to a roll-to-roll mass production apparatus, mass production of solar cells having a tilted band profile is made possible.

That is, according to the present invention, first, a wall is provided along the base, an exhaust pipe directly connected to an exhaust device is provided at one end of the wall, and the active species (A) and the precursor are provided at the other end. By providing an inlet through which the body (B) can be mixed and introduced, the flow (AB) can be created in a direction along the surface of the substrate.

In addition, the flow (AB) is introduced perpendicularly to the surface of the substrate, and a gas (C) whose flow direction is 10 ° or more and 90 ° or less with respect to the flow direction of the flow (AB) is introduced. Accordingly, the direction of the flow (AB) can be changed from a direction perpendicular to the surface of the substrate to a direction along the surface of the substrate. At this time, it is also possible to activate the gas (C) in advance and to introduce the gas, thereby effecting the cleaning effect of the substrate surface by pre-sputtering, and the reaction between the active species (A) and the precursor (B) on the substrate surface. And other effects can be expected.

Furthermore, the flow (AB) is introduced along the surface of the substrate by introducing the flow (AB) along the surface of the substrate by introducing the flow (AB) to the surface of the substrate at an angle of 30 ° or more and 90 ° or less. It is also possible to flow in different directions.

 Hereinafter, the present invention will be described in detail based on specific examples.

Embodiment 1 FIGS. 1 (A), 1 (B) and 1 (C) are schematic views of a mass production apparatus of a photovoltaic device of the present invention, and FIG. FIG. In FIG. 1 (A), 101 is a stainless steel substrate, and 102 and 103 are a roll for sending out and a roll for winding up, respectively. 102 and 103 are in the atmosphere. 104
Is a vacuum chamber for mass production of solar cells, and 104 is a load chamber that performs both preliminary exhaust and preliminary heating. 104 (N), 104 (I) and 104 (P) are film forming chambers for an N layer, an I layer and a P layer, respectively. 104 (O) is a transparent conductive film deposition chamber, each of which has an independent exhaust unit.

Next, FIG. 1B is a drawing for explaining a film formation chamber used for 104 (N) and 104 (P). In the same figure, 105 is a quartz glass tube capable of introducing hydrogen or a gas containing hydrogen, while 106 is a quartz glass tube having a coaxial double tube structure with 105,
Silicon or non-silicon periodic table group III, IV
It is possible to introduce a gas containing a Group V element and a Group V element and halogen. Reference numeral 107 denotes a plasma generator, which includes a microwave power supply unit (not shown) and converts a part or all of the gas introduced from 105 and 106 into plasma. Further, 107 can use an RF plasma generator instead of the microwave plasma generator. Reference numeral 108 denotes an infrared lamp for heating the stainless steel roll substrate 101, which raises and maintains the temperature of the 101 to a predetermined temperature.

In the chamber 104 (N), the N layer is formed in the chamber 104 (P).
In the following, a P layer is formed, but an example of an N layer will be described. First, 101 is heated to a predetermined temperature, and a quartz glass tube 105 is heated.
And a predetermined amount of SiF ₄ and PH ₃ are passed through the quartz glass tube 106. As described in the operation of the present invention, when a predetermined microwave effective power is supplied from a microwave power source to generate plasma, H ₂ , Ar, SiF ₄ and PH ₃ are partially or entirely activated, and quartz glass is activated. The N-type a-Si film is transported onto the 101 while being associated at the outlet of the tube 106, and an N-type a-Si film is formed on the 101.

Next, the formation of a P layer of microcrystal silicon (hereinafter abbreviated as μC-Si) will be described. The formation of the P layer is different from the formation of the N layer in that BF ₃ is introduced from 106 instead of PH ₃ and that the flow rate of H ₂ is increased by about 50% as a condition for forming μC-Si. Thus, the P layer of μC-Si is
Table 2 summarizes the conditions for forming the N layer and the P layer, which can be deposited thereon.

Subsequently, a method for forming the I layer, which is a feature of the present invention, will be described.
A description will be given by taking a tilted a-SiGe layer as an example.

FIG. 1 (C) is a schematic view of the I-layer film forming chamber 104 (I) for explaining the features of the present invention. In the figure, a stainless steel substrate 101 is fed to 104 (I) in a state where an N-layer of a-Si is laminated in an N-layer deposition chamber. 109a and b are microwave cavity type cavity resonators, 111a and b are meshes, 11
2a, b are alumina windows, 110a, b are gas inlets. 110a, b
A more predetermined gas and a predetermined microwave effective power are supplied to 109a and 109b (collectively shown in Table 3), and a predetermined trigger is applied to generate plasma in both the 109a and 109b cavities, The active species and the precursor are introduced into the film formation chamber 113 through the meshes 111a and 111b to form a flow 116. This flow 116 passes through a space surrounded by the wall 117 along the surface of the base 101 and the surface of the base 101, and is further exhausted from the exhaust pipe 114 to the exhaust system. The I-layer a-SiGe thus formed
The film has a distribution in which the concentration of Ge contained in the I layer gradually increases as approaching the exhaust port.
Eg tends to be small.

Therefore, the I layer of the solar cell as shown in FIG. 2 is laminated on the rolled stainless steel substrate on which the N layer is laminated in advance. Then, after exiting 104 (I), 101 is 104
After a predetermined P layer is laminated in (P), a transparent conductive film is laminated under predetermined conditions at 104 (O) and wound around 103.

FIG. 2A is a schematic view of the mass-produced solar cell of the present embodiment, and FIG. 2B shows the Eg profile of the I layer according to the present embodiment. 201 is a stainless steel substrate, 202N, 202I, 202P
Denotes an a-Si N layer, an a-SiGe inclined type I layer, and a μC-Si P layer. As described above, after the precursor and the active species are associated with each other, by guiding the obtained flow in a direction along the surface of the substrate, it is possible to easily form an a-SiGe gradient layer.

As shown in Table 5, the a-SiGe solar cell prepared in this manner was used in a roll-to-roll production apparatus as shown in Table 5.
-Compared to an a-SiGe solar cell having an Eg of 1.4 (eV) without a graded layer of SiGe, the photoelectric conversion efficiency?
(%).

Example 2 Next, Example 2 describes an a-SiGe solar cell having a buffer layer and an inversely inclined band profile. First, in the same manner as in the first embodiment, in the mass production apparatus shown in FIG. 1 (A), the present embodiment is performed using a mass production apparatus in which the I-layer deposition chamber of 104 (I) is formed as the deposition chamber shown in FIG. Will be described.

In the figure, 301 (F) and (R) are gas introduction pipes, 302
(F) and (R) are hydrogen or a gas introduction tube containing hydrogen,
303 (F) and (R) are gas introduction pipes containing Si, an element of Group IV of the periodic table and halogen. (F) and (R) in each figure indicate the Front portion and the Re, respectively, when viewed from the introduction direction of the base 101.
means ar part. 304 is a microwave plasma generator (ancillary equipment not shown). Reference numeral 305 denotes a pyrolysis heater 307 (F), (R), and 308 (F), (R) each indicate an arrow indicating a main gas flow direction. Reference numeral 309 denotes a tungsten lamp for maintaining the base 101 at a predetermined temperature. Table 4 summarizes the predetermined gas flow rates, effective microwave power, and heater temperature. The mixed gas of H ₂ and Ar introduced from 302 (F) is turned into a plasma state by 304, generates many active hydrogen atoms, is introduced from 303 (F) at 306 (F), and is thermally decomposed by 305 The precursor generated from the mixed gas of Si ₂ F ₆ and GeF ₄
8 (F) is transported in the flow direction shown in FIG.
A mold a-Si layer is laminated. ) Is first introduced vertically. Further, a predetermined Ar is converted to a predetermined angle θ _F from 301 (F).
When introduced at 307, the flow introduced perpendicularly to the 101 substrate is 307.
It can be changed in the direction indicated by the arrow (F). In FIG. 3, the gas flow shown by 308 (R) can be similarly generated by the gas introduction pipes installed substantially symmetrically to this. 301 flow and theta _F and theta _R of (F) and 301 (R) gas introduced more it is possible to suitably adjusted to optimize the buffer layer opposite the inclined layer, theta _F
It can be adjusted in the range below 90 ° or more 10 ° for and theta _R.

As a result of this optimization, the preparation conditions were as summarized in Table 4. FIG. 4 shows the profile of Eg in the film thickness direction of the reverse-tilt a-SiGe solar cell having the buffer layer formed under the above conditions. In addition, as summarized in Table 5, a large effect was observed in the conversion efficiency from 8.0 (%) to 10.0 (%) as compared with the a-SiGe solar cell with Eg = 1.4 (eV) of (conventional example) without inclination. Can be

Example 3 Next, it will be shown that the present invention is effective for a roll-to-roll mass production apparatus for a triple type solar cell having the configuration shown in FIG. FIG. 5A is a schematic diagram of the present embodiment. In the same figure, 504 is a preheating chamber, 505 (N),
(I), (P), 506 (N), (I), (P), 507
In each of the deposition chambers (N), (I), and (P), the subscript (N) is N.
The layer and the suffix (I) indicate an I layer and the suffix (P) indicates a P layer deposition chamber. Schematic diagrams of 505 (I) and 506 (I)
(B) In the figure, a bottom layer and a middle layer of a buffer layer and a reverse-slope a-SiGe are formed, respectively. FIG. 5 (C) is a schematic view of 507 (I), in which a buffer layer and a top layer of inversely inclined a-SiC are formed, respectively. Reference numeral 508 denotes a deposition chamber for a transparent conductive film.
5 (B) and 5 (C), the suffixes (F) and (R) of the figure numbers correspond to the Front side and the Rear side with respect to the introduction direction of the substrate 501, as in the second embodiment. It is. Fifth (B)
In the figure, 509 (F), (R), 510 (F), and (R) are gas introduction tubes, 511 (F) and (R) are microwave plasma generators, and 513 is a tungsten lamp for heating a substrate. . θ
_F and θ _R are angles formed between the substrate 501 and the gas ejection pipe, respectively.

In FIG. 5C, reference numerals 513 and 514 denote gas introduction pipes,
Reference numeral 15 denotes a plasma generator. θ is the gas inlet tube and substrate 50
It is the angle between 1 and.

Table 6 summarizes the film forming conditions in each I layer film forming chamber. First, a buffer layer of the bottom layer and an a-SiGe
The I layer will be described. In FIG. 5 (B), 509
A gas containing hydrogen is introduced from (F) and (R), respectively.
The plasma state is activated by the microwave plasma generators 511 (F) and (R), respectively, and is transported to the film forming chamber, while the SiF introduced from the 510 (F) and (R) is on the way.
₄ and GeF _{4, respectively,} and undergoing a chemical reaction to form a precursor while forming a flow indicated by 512 (F) and (R), respectively.
A deposited film of a-SiGe is formed on the top, the band gap of which tends to become smaller as the distance from the gas inlet tube increases. As in the previous embodiment, the base 501 has an N layer laminated in advance. theta _F and theta _R is the gas introducing pipe and the substrate
The angle formed by 501, but a reverse-slope a with a buffer layer
-Each can be adjusted from a minimum of 10 ° to a maximum of 90 ° according to the optimization of SiGe solar cells. In a triple cell, a bottom layer having a high infrared sensitivity and a small band gap, for example, about 1.40 (eV) is currently optimal, but in the present embodiment, the minimum band gap of the reversely inclined portion of the bottom layer is It can be optimized as 1.40 (eV), that of the middle layer as 1.65 (eV).

In the present embodiment, optimization was attempted particularly by setting the balance of the flow rates of the respective gases, the microwave effective power, and the conditions of θ _F and θ _R.

In Table 3, since the device configuration of the bottom layer and the middle layer is almost the same for convenience, the figure with a dash after the figure number is shown as the figure number of the middle layer. The reverse slope band profiles having the bottom layer and the middle buffer layer are basically the same, but the difference is that the bottom layer is designed to have a small Eg in order to increase the long wavelength sensitivity. For this reason, the flow rate of GeF ₄ is six times as large as that of the middle layer, and the thickness of the bottom layer is about twice as large as that of the middle layer. It is about bigger.

Next, the creation of the top layer will be described. What is characteristic here is that only one gas inlet tube is used, and an inverted-slope type I layer having an a-SiC buffer layer as shown in FIG. 6 can be formed.

In FIG. 5 (C), hydrogen and Ar
Is introduced through the 514 and the microwave plasma generator 515
Into a plasma by the gas introduction pipe 51.
From 4, SiF ₄ and CF ₄ are introduced and associated to form flows 516 and 517 while undergoing a chemical reaction. The flow 516 flows in a direction opposite to the traveling direction of the base 501, and the flow 517 flows in a forward direction. In a region sandwiched between 516 and 517, an a-SiC film having a small C (carbon) component is deposited on 501, and an a-SiC film having a large C component is deposited on 501 as the flow proceeds in the flow direction of 516. Similarly, in the flow direction of 517, an a-SiC film having a large C component is deposited on 501 as the flow proceeds in the flow direction. In this way, it is possible to form a reverse-tilted a-SiC top layer having a buffer layer shown in FIG. The positioning with respect to the thickness direction becomes Eg minimum is possible by choosing x ₁ of the first 5-3 Figure appropriately the angle θ of the position and the gas introducing pipe and the substrate 501 of x _2.

In this manner, a transparent conductive film is vapor-deposited on the substrate 508 on which the bottom, middle, and top layers are laminated in this order, and wound up by the roll 503. Then, the conversion efficiency of the solar cell fabricated as described above, that is, the solar cell of a triple structure having a buffer layer in each layer and an inversely inclined band profile was 13.5 (%).

On the other hand, a-SiGe (Eg = 1.40 (eV)) and a-Si (Eg = 1.70) optimized for the bottom layer, middle layer, and top layer, respectively.
(EV)), and the conversion efficiency of the triple solar cell obtained using a-SiC (Eg = 2.2 (eV)) was improved by 1.4 (%) compared to 12.1 (%). You can see that

[Effects of the Invention] As described above, particularly when a high-performance photovoltaic element using an a-SiGe and a-SiC inclined band profile is produced in a roll-to-roll mass production apparatus, the present invention According to the feature that the inclined band gap is of good quality and smoothly inclined, not only the best one can be obtained, but also it is not necessary to increase the number of film forming chambers, reduce capital investment, and control items of equipment operation. As a result, there is an effect that a high-performance photovoltaic element can be supplied to the market at a low cost.

[Brief description of the drawings]

FIG. 1 (A) is a schematic view of a basic solar cell mass production apparatus necessary for carrying out the present invention. FIG. 1 (B) is a cross-sectional view of a basic film forming chamber for forming an N layer and a P layer of a solar cell. FIG. 1 (C) is a diagram showing an example of the I described in Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view of a film formation chamber for forming a layer. FIG. 2 is a diagram showing the configuration of the solar cell described in Example 1 and the band profile of the I layer. FIG. 3 is a schematic diagram of a film forming chamber for forming an I layer of the solar cell described in Example 2. FIG. 4 is a diagram of a configuration and a band profile of the solar cell of the example. FIG. 5 (A) is a schematic view of a mass production apparatus for producing a triple solar cell in Example 3, and FIG. 5 (B) is for producing a bottom layer and a middle layer of a-SiGe in Example 3. FIG. 5C is a schematic view of a film forming chamber for forming a top layer. FIG. 6 is a diagram showing a configuration of the triple solar cell of the same embodiment and a reverse-slope band profile having each I-layer buffer layer. 7 (A), 7 (B), and 7 (C) are diagrams showing band profiles of a conventional photovoltaic element, respectively. Respectively
The PIN type has a light receiving surface on the P type side, and shows the band profile of the I layer. FIG. 7 (A) shows an inclined type in which Eg is large on the light receiving surface side and is smoothly reduced in the film thickness direction. 7th (B)
The figure shows an inverted tilt type designed to promote hole drift in the valence band. FIG. 7 (C) shows an inversely inclined band profile having a buffer layer provided with a buffer layer on the light receiving surface side in FIG. 7 (B). FIG. 8 is a schematic view of a deposited film forming apparatus for explaining the operation of the present invention, and FIG. 9 shows the distribution of Eg on the substrate 6 of the a-SiGe film and the Ge concentration in the film formed by this apparatus. It is a graph. In FIG. 1 (A), 101: a substrate of a stainless steel substrate, 102: a substrate feeding roll, 103: a substrate winding roll, 104: a preheating chamber, 104 (N): an N-layer film forming chamber, 104 (I): I-layer film forming chamber, 104 (P): P-layer film forming chamber, 104 (O): Transparent conductive film deposition chamber. In FIG. 1 (B), 105, 106... Gas introduction pipe, 107... Plasma generator, 108... Infrared lamp. In FIG. 1 (C), 109a, 109b... Cavity plasma generating chamber, 110a, 110b... Gas inlet, 111a, 111b... Mesh, 112a, 112b... Alumina ceramics, 113. Seed reaction chamber, 114: exhaust pipe, 115: tungsten lamp, 116: arrow indicating flow of active species and precursor, 117: wall provided in the direction along the surface of substrate 101. In FIG. 2 (A), 201: a substrate of a stainless steel substrate, 202 (N): an N-layer of a-Si, 202 (I): an a-SiG having an inclined band profile
e I layer, 202 (P)... μC-SiC P layer. In FIG. 3, 301 (F), (R)... Gas introduction pipe, 302 (F), (R)... Hydrogen or hydrogen-containing gas introduction pipe, 303 (F), (R)... Halogen And a gas introduction tube containing a Group IV element of the periodic table, 304... A microwave plasma generator, 305... A pyrolysis heater, 306 (F), (R)... , 307 (F), (R)... Arrows indicating gas flow, 308 (F), (R)... Arrows indicating precursor and active species flows, 309... Tungsten heater, θ _F , θ _R ... The angle between the base and the gas inlet tube. In FIG. 4, 401: a base of a stainless steel substrate; 402 (N): an N-layer of a-Si; 402 (I): an a-SiGe layer of a reverse inclined hand profile having a buffer layer; ): P layer of μC-SiC, 403: Transparent conductive film. In FIG. 5 (A), 501: a base of a stainless roll substrate, 502: a substrate feed roll, 503: a substrate winding roll, 504: a preheating chamber, 505 (N), 506 (N), 507 (N): a-Si N-layer film forming chamber; 505 (I), 506 (I): reverse-graded band profile a-SiGe, having a buffer layer, I-layer film forming chamber; 507 (I) )... I-layer deposition chamber of a-SiC having a buffer layer and reverse slope band profile, 505 (P), 506 (P), 507 (P)... P-layer deposition chamber of μC-SiC, 508 … Transparent conductive film deposition chamber. 5 (B) and 5 (C), 509 (F), (R), 513... Hydrogen or a gas containing hydrogen, 510 (F), (R), 514. Introduction tube for gas containing Group IV element, 511 (F), (R), 515 ... Microwave plasma generator, 512 (F), (R), 516,517 ... Precursor and active species Arrows indicating flow, 513: infrared lamp, θ _F , θ _R , θ: angle between gas introduction tube and substrate, x ₂ , x ₂ … position of gas introduction tube in 507 (I) film forming chamber The distance from the indicated chamber wall. In FIG. 6, 601 has a stainless steel roll substrate, 602 (N), 603 (N), 604 (N) has an N-layer of a-Si, and 602 (I), 603 (I) has a buffer layer. A-SiGe I layer having an inversely inclined band profile, 604 (I)... A-SiC I layer having an inversely inclined band profile having a buffer layer, 602 (P), 603 (P), 604 ( P): P layer of μC-SiC, 605: Transparent conductive film. In FIG. 8, 1... Gas introduction tube, 2... Gas introduction tube, 3... Microwave plasma generator, 4... Vacuum chamber, 5... Arrow, 6 ... Base.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 16/00-16/56 H01L 31/04

Claims (8)

(57) [Claims] 1. A raw material gas containing an active species (A) obtained by activating a gas containing at least hydrogen, at least silicon and one or more elements selected from Group IV of the periodic table other than silicon, and a halogen. Of the precursor (B) obtained by activating the water, the flow (AB) obtained by mixing the precursor (B) is guided to a substrate moving in a direction along its surface, and the band gap increases on the substrate on the substrate side In the deposition film forming method for forming a functional deposition film having such a tilted band profile, the active species (A) and the precursor (B) are respectively disposed on the downstream side in the moving direction of the substrate through separate introduction tubes. Introduced into the deposition space at an angle to the substrate toward the deposition space on the upstream side in the moving direction of the substrate and
After the flow (AB) flows in a deposition space surrounded by the surface of the substrate of a wall provided in a direction along the surface of the substrate, the flow is exhausted from an upstream side in the moving direction of the substrate. A method for forming a deposited film. 2. An angle between the direction of the flow of the gas (C) and the direction of the flow (AB) of the gas (C) containing no element of Group IV of the periodic table is 10 ° or more and 90 ° or less. The method for forming a deposited film according to claim 1, wherein the introduction is performed such that 3. The method according to claim 2, wherein the gas (C) is activated in advance. 4. A deposited film using a source gas for forming a deposited film containing at least silicon and a source gas for forming a deposited film containing at least one element selected from Group IV of the periodic table other than silicon. In a deposition film forming method for forming a functional deposition film having an inclined band profile such that a band gap is increased on a substrate side on a substrate which is introduced and moved into a formation space, the deposition film forming gas is The raw material for forming a deposited film at an angle with respect to the substrate on the downstream side in the moving direction of the substrate and upstream from the end of the deposited film forming space toward the upstream in the moving direction of the substrate and toward the deposited film forming space. A method for forming a deposited film, wherein each of the gases is introduced into a deposited film forming space from a different introduction pipe, and the gas is exhausted upstream from the introduction position in the moving direction of the substrate. 5. The deposition film forming gas comprises a precursor (B) obtained by activating a source gas containing at least silicon and at least one element selected from Group IV of the periodic table other than silicon. The method for forming a deposited film according to claim 4, wherein a flow (AB) obtained by mixing the activated species (A) obtained by activating a gas containing hydrogen is formed. 6. A raw material gas containing an active species (A) obtained by activating a gas containing at least hydrogen, at least silicon and one or more elements selected from Group IV of the periodic table other than silicon, and a halogen. Of the precursor (B) obtained by activating the water, the flow (AB) obtained by mixing the precursor (B) is guided to a substrate moving in a direction along its surface, and the band gap increases on the substrate on the substrate side In a deposited film forming apparatus for forming a functional deposited film having such a tilted band profile, the active species (A) and the precursor (B) are located on the downstream side in the moving direction of the substrate and upstream in the moving direction of the substrate. A wall provided in a direction along the surface of the substrate so as to be introduced at a side and at an angle toward the deposition film formation space; The separate introduction pipes for each of the active species (A) and the precursor (B) provided at an angle to the moving substrate disposed on the flow side, and the flow (AB) is After flowing in a deposition film forming space surrounded by the wall provided in the direction along the surface of the substrate and the surface of the substrate, the substrate in the space is evacuated from the upstream side in the moving direction of the substrate. A deposition film forming apparatus provided with an exhaust port provided on the downstream side in the moving direction of the film. 7. The gas (C) containing at least an element of Group IV of the periodic table, wherein the angle between the flow direction of the gas (C) and the direction of the flow (AB) is 10 ° or more and 90 ° or less. Claim (6) characterized by having means for introducing
3. The deposited film forming apparatus according to item 1. 8. The deposition film forming apparatus according to claim 7, further comprising means for activating said gas (C) in advance.