JP2000087234A - Device for producing compound film and production of compound film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compd. thin film producing device in which the problems in the conventional CIS film formation are solved and capable of producing a CIS thin film of high quality and large area. SOLUTION: This device is provided with a main vacuum chamber having several openings on the circumference and a rotary drum 5 arranged in the main vacuum chamber 1, mounted with a substrate on the outer circumference and rotating it. Moreover, for feeding sputtering particles from the openings toward the substrate, each opening is fitted with a sputtering chamber 3. Furthermore, for feeding vapor from the openings to the substrate, a vacuum evaporating chamber 2 is fitted as well. At this time, the rotary drum 5 is disposed so as to make a rotary axis horizontal. One of the openings is disposed at the bottom part of the main vacuum chamber 1, and the vacuum evaporating chamber 2 is fitted to the opening at the bottom part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing apparatus for manufacturing a compound thin film, and more particularly to a manufacturing apparatus suitable for forming a compound by evaporating some elements and flying other elements by sputtering. .

[0002]

2. Description of the Related Art CuInSe having a chalcopyrite type structure
_2. Description of the Related Art A solar cell using a (CIS) -based thin film has high photoelectric conversion efficiency, is low in cost, and has excellent long-term stability. In particular, Cu (I
The conversion efficiency of n _1-x Ga _x ) Se ₂ (CIGS) solar cells has improved significantly in recent years, exceeding 17% in lab size and over 14% in mini-modules. Lab-size high-efficiency CIS-based solar cells are formed by a multi-source simultaneous vapor deposition method. On the other hand, the large area module is C
It is manufactured by a selenization method or the like in which a metal laminated film containing u, In and Ga is heat-treated in H ₂ Se gas. Note that the metal laminated film before selenization is referred to as a precursor film (precursor film). Hereinafter, a method of forming a CIS-based solar cell including a CIGS-based solar cell will be specifically described.

1) Multiple Source Simultaneous Deposition Method A typical method of the multiple source simultaneous deposition method is NRE in the United States.
There is a three-step method developed by L (National Renewable Energy Laboratory) and a simultaneous vapor deposition method of the EC group. The three-step method is described in, for example, JRTuttle, JSWard, A. Duda, TABerens,
MAContreras, KRRamanathan, ALTennant, J. Keane,
EDCole, K.Emery and R.Noufi: Mat.Res.Soc.Symp.Pro
c. Vol.426 (1996) p.143. In addition, the simultaneous vapor deposition method is, for example, L. Stolt et al .: Proc. 13th ECPVSEC
(1995, Nice) 1451. In the three-step method, first, In, Ga, and Se are co-deposited in a high vacuum at a substrate temperature of 300 ° C., and then the temperature is raised to 500 to 560 ° C. to form Cu, Se.
After the simultaneous deposition of In, Ga, and Se, a graded band gap CIGS film having a sloped forbidden band width can be obtained. The EC group's method is an improvement in which the bilayer method developed by Boeing, which deposits Cu-excess CIGS in the initial stage of vapor deposition and In-excess CIGS in the latter stage, can be applied to an in-line process. The bilayer method is based on WEDevaney, WSChen, JMSte
wart, and RAMickelsen: IEEE Trans.Electron.Devices
37 (1990) 428.

[0004] In both the three-step method and the simultaneous vapor deposition method of the EC group, a CuGS-excess CIGS film composition is formed during the film growth process.
Since the liquid phase sintering using the phase separated liquid phase Cu _2-x Se (x = 0 to 1) is used, there is an advantage that a large grain size occurs and a CIGS film having excellent crystallinity is formed. However, these are basically vacuum evaporation methods, and have a problem in the stable supply of evaporation flux over a large area. Therefore, they are not essentially suitable for increasing the area of a multi-component compound thin film.

2) Selenization method The selenization method is also referred to as a two-step method, in which a Cu layer / In
Layer or a metal precursor of a laminated film such as a (Cu-Ga) layer / In layer is formed by a sputtering method, a vapor deposition method, an electrodeposition method, or the like, and is formed at 450 to 550 ° C. in selenium vapor or hydrogen selenide.
By heating to about
This is a method for producing a selenium compound such as (In _1-x Ga _x ) Se ₂ . This method is called a gas-phase selenization method. In addition, a solid-phase selenization method in which solid selenium is deposited on a metal precursor film and selenized by a solid-phase diffusion reaction using the solid selenium as a selenium source. There is. Currently, the only successful mass production of a large area is a method in which a metal precursor film is formed by a sputtering method suitable for increasing the area, and this is selenized in hydrogen selenide.

However, in this method, the volume of the film is approximately doubled at the time of selenization, so that internal strain is generated and voids of about several μm are generated in the formed film, and these voids are generated with respect to the substrate. There is a problem that it adversely affects adhesion and solar cell characteristics and is a limiting factor in photoelectric conversion efficiency (BMBasol, VKKapur, CRLeidholm, R.Roe, A.Ha
lani, and G. Norsworthy: NREL / SNL Photovoltaics Prog.
Rev. Proc. 14th Conf.-A Joint Meeting (1996) AIP Conf.
Proc. 394.).

[0007] In order to avoid such rapid volume expansion at the time of selenization, a method of previously mixing selenium in a metal precursor film at a certain ratio (T. Nakada, R. Ohnish)
i, andA.kunioka: "CuInSe ₂ -Based Solar Cells by Se-Va
por Selenization from Se-Containing Precursors "So
lar Energy Materials and Solar Cells 35 (1994) 204-2
14.) or selenium sandwiched between thin metal layers (eg Cu layer /
In layer / Se layer: laminated with Cu layer / In layer / Se layer)
The use of multilayered precursor films has been proposed (T. Nakad
a, K.Yuda, and A.Kunioka: "Thin Films of CuInSe ₂ Prod
uced by ThermalAnnealing of Multilayers with Ultra
-Thin stacked Elemental Layers "Proc. Of 10th Euro
pean Photovoltaic Soalr Energy Conference (1991) 887
-890.). As a result, the above-described problem of the accumulation expansion is avoided to some extent.

However, including such a method,
There are issues that apply to all selenization methods. That is, since a metal laminated film having a predetermined composition is used first and selenized, a degree of freedom in controlling the film composition is extremely low. For example, at present, a high-efficiency CIGS-based solar cell uses a graded band gap CIGS thin film having a Ga concentration inclined in the film thickness direction. In order to produce such a thin film by the selenization method, Cu-Ga When depositing an alloy film, depositing an In film thereon, and selenizing the In film, the Ga concentration is inclined in the film thickness direction using natural thermal diffusion (K. Kushiya, I. Sugiyama, M. et al. Tachiyuki, TK
ase, Y.Nagoya, O.Okumura, M.Sato, O.Yamaseand H.Takesh
ita: Tech.Digest 9th Photovoltaic Science and Engin
eering Conf.Miyazaki, 1996 (Intn.PVSEC-9, Tokyo, 1996)
p.149.). However, in this method, a Ga-excess CIGS film is first formed, so that the crystal grain size is reduced and many crystal grain boundaries are generated. Carriers are trapped in the crystal grain boundaries, which adversely affects the characteristics of the solar cell and is a limiting factor of the photoelectric conversion efficiency. In particular, high quality CIG with large particle size
To obtain an S thin film, as described above, a CuGS-excess CIGS film composition is formed during the film growth process, and the liquid phase Cu _2-x Se phase-separated is obtained.
The use of is important. However, in the selenization method, it is difficult to realize such a film forming process for the reasons described above.

3) Sputtering method On the other hand, the sputtering method is suitable for increasing the area.
Many techniques have been tried as a method for forming a uInSe ₂ thin film. For example, a method using CuInSe ₂ polycrystal as a target, or a method using Cu ₂ Se and In ₂ Se ₃ as targets and using a mixed gas of H ₂ Se and Ar as a sputtering gas 2
Source sputtering method (JHErmer, RBLove, AKKhanna, SCLe
wis and F. Cohen: "CdS / CuInSe ₂ Junctions Fabricated
by DC Magnetron Sputtering of Cu ₂ Se and In ₂ Se ₃ "Pr
oc.18th IEEE Photovoltaic Specialists Conf. (198
5) 1655-1658.) Is disclosed. Also, a three-source sputtering method for sputtering a Cu target, an In target, a Se or CuSe target in an Ar gas has been reported (T. Nakada, K. Migita, A. Kunioka: "Polycryst").
alline CuInSe ₂ Thin Films for Solar Cells by Three
-Source Magnetron Sputteing "Jpn. J. Appl. Phys. 3
2 (1993) L1169-L1172; and T. Nakada, M. Nishioka, a
nd A. Kunioka: "CuInSe ₂ Films for Solar Cells by Mu
lti-Source Sputtering of Cu, In, and Se-Cu Binary
Alloy "Proc. 4 th Photovoltaic Science and Engine
ering Conf. (1989) 371-375.).

[0010] However, in these sputtering methods,
Se negative ions and neutralized high-energy Se particles emitted from the target of Se or Se compound are accelerated by the electric field between the target and the plasma and bombard the film surface, so that many defects are generated in the thin film. However, there was a problem that a high quality CIS thin film could not be obtained. Therefore, the conversion efficiency of the solar cell using the CIS film manufactured by such a sputtering method is low, and is about 6-8%.

4) Hybrid sputtering method If the problem of the sputtering method described above is that the film surface is damaged by Se negative ions or high-energy Se particles, it can be avoided by changing only Se to thermal evaporation. It is. Nakada et al. Formed a CIS thin film with few defects by a hybrid sputtering method in which Cu and In metal were subjected to direct-current sputtering and only Se was deposited, and the conversion efficiency was 10%.
CIS solar cells exceeding T. (T. Nakada, K. Migita,
S.Niki, and A.Kunioka: "Microstructural Characteriz
ation for Sputter-Deposited CuInSe ₂ Films and Phot
ovoltaic Devices "Jpn. Appl. Phys. 34 (1995) 4715-472
1.) Rockett et al. Also preceded this by toxic H ₂ S
A hybrid sputtering method aimed at using Se vapor instead of e-gas has been reported (A. Rockett, TC
Lommasson, LCYang, H.Talieh, P.Campos and JAThor
nton: Proc. 20 th IEEEPhotovoltaic Specialists Con
f. (1988) 1505.). Furthermore, a method of sputtering in Se vapor to compensate for Se deficiency in the film has been reported earlier (S. Isomura, H. Kaneko, S. Tomioka, I. Nakatani, and K. Ma).
sumoto: Jpn. J. Appl. Phys. 19 (Suppl. 19-3) (1980) 2
3.) However, in these hybrid sputtering methods, Se vapor contaminates the metal target, and C
Since a selenide such as uSe or InSe is formed, sputter discharge becomes unstable, and there is a problem that it is difficult to form a uniform film over a large area and reproducibility of film quality deteriorates. However, these contaminants are radio frequency (RF)
In the sputtering method, the insulating film is also sputtered, so that it can be reduced to some extent. However, the current RF sputtering method is not suitable for mass production of a large area because large power is required.

5) Other methods As other CIGS film forming methods, there are reported examples such as a screen printing method, a proximity sublimation method, a MOCVD method, and a spray method.
No system thin film was obtained.

6) JP-A-63-192865 discloses that a plurality of sputtering chambers are mounted on the outer periphery of a cylindrical main vacuum chamber, and the substrate is mounted on a drum-shaped substrate holding mechanism and rotated in the main vacuum chamber. A sputtering apparatus is disclosed. This publication also discloses that a CIS film is formed using this sputtering apparatus. further,
This publication describes that one of the sputtering chambers attached to the main vacuum chamber may be a vacuum evaporation chamber.

[0014]

In the above prior art, the multi-source simultaneous vapor deposition method can obtain a high-quality CIGS thin film, but has a problem in a large area stable supply of the evaporation flux. However, it is not suitable for large-area film formation of a multi-component compound thin film.

Further, as described above, the selenization method has problems such as internal strain due to volume expansion at the time of selenization, generation of voids in the film, and reduction in adhesion of the film to the substrate.
Further, a problem that applies to all selenization methods is that a metal precursor film having a predetermined composition is used and selenized, so that it is impossible to control the film composition during the film forming process. In other words, by changing the evaporation amount of the constituent elements, a CIGS film composition having an excessive amount of Cu is formed at an intermediate stage of the film growth, and the liquid phase sintering mode using the liquid phase Cu _2-x Se separated into phases is used to increase the thin film thickness. A film forming method such as a three-step method for quality improvement cannot be applied. Therefore, it is difficult to achieve both forbidden band width control and high quality thin film crystal required for a high efficiency solar cell.

On the other hand, since the sputtering method is suitable for increasing the area, many methods have been tried as a CuInSe ₂ thin film forming method. However, as described above, S
Lattice defects occur in the thin film due to film surface damage caused by Se negative ions or high energy Se particles released from e or its compound target, and a high quality CIS based thin film cannot be obtained. Further, in order to avoid this, in the hybrid sputtering method in which Cu and In are deposited by sputtering, and only Se is changed to thermal evaporation, there has been a problem of instability of sputter discharge due to contamination of a metal target by Se vapor.

When a sputtering apparatus described in JP-A-63-192865 is used for manufacturing a CIS film, the film surface damage due to Se negative ions or high-energy Se particles is the same as in the above-described sputtering method. Therefore, it is considered that a problem that lattice defects occur in the thin film occurs.
Further, although one of the sputtering chambers described in JP-A-63-192865 is described as a vacuum deposition chamber,
This publication does not describe anything further.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compound thin film manufacturing apparatus capable of solving the above-mentioned problem of forming a conventional CIS based film and producing a high quality, large area CIS based thin film. And

[0019]

According to the present invention, there is provided an apparatus for producing a compound film as described below.

That is, a main vacuum chamber having a plurality of openings around it, a rotating drum disposed in the main vacuum chamber and mounted on the outer periphery for rotating a substrate, and sputtered particles from the opening toward the substrate. And at least one sputter chamber attached to the opening, and the at least one vacuum evaporation chamber to supply vapor from the opening to the substrate, wherein the rotating drum is rotatable. An axis is arranged horizontally, and one of the plurality of openings is provided at a bottom of the main vacuum chamber, and the vacuum evaporation chamber is attached to an opening provided at the bottom. An apparatus for producing a compound thin film, characterized in that:

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

The inventors of the present application disclose Japanese Patent Application Laid-Open No. 63-1928.
No. 65, one of the sputtering chambers is changed to a vacuum deposition chamber, and this vacuum deposition chamber is
It is considered that the use of e for evaporating makes it possible to form a CIS-based film by the hybrid sputtering method using the present apparatus. Then, it was predicted that the above-mentioned conventional problem could be solved by using such an apparatus, and the present inventors studied. As a result, the film forming method using this apparatus can prevent lattice defects from being generated in the thin film due to damage to the film surface due to Se negative ions or high energy Se particles, and furthermore, prevent sputter discharge due to metal target contamination. It turns out that the problem of stabilization can be solved. However, it is difficult to make the distribution of Se vapor uniform in the in-plane direction of the film, and a large-area CIS-based film cannot be obtained. Then, the present inventors investigated the cause of the non-uniform spatial distribution of Se vapor, and found that there was a problem in the positional relationship between the Se liquid surface during deposition and the substrate surface.

More specifically, the apparatus described in Japanese Patent Application Laid-Open No. 63-192865 is a device in which the rotating shaft of a drum-shaped holder for supporting a substrate is vertically arranged, and therefore, the device described in Japanese Patent Application Laid-Open No.
When the vacuum evaporation chamber is mounted, the Se vacuum evaporation chamber is mounted on the side of the vacuum chamber, and Se vapor is introduced from the opening on the side of the vacuum chamber. However, when Se is heated for vapor deposition, it becomes a low melt of clay, and the liquid level of the melt becomes horizontal due to gravity.
Se vapor first rises upward in the vacuum evaporation chamber,
Then, it is drawn horizontally toward the opening on the side of the vacuum chamber due to the difference in the degree of vacuum, and is vapor-deposited on the substrate facing the opening. Therefore, the Se melt surface and the main plane of the substrate have a positional relationship of 90 degrees. For this reason, the distance between the melt surface of Se and the substrate surface (the moving distance until Se vapor reaches the substrate) differs depending on the position on the substrate, and the distribution of Se vapor is kept constant in the main plane direction of the substrate. It becomes difficult.

In addition, a Se film is formed on the moving path of the Se vapor as the deposition proceeds. In particular, since the Se melt surface and the principal plane of the substrate have a positional relationship of 90 degrees, the moving path of Se vapor to the substrate is complicated,
The efficiency of vapor deposition on the substrate is poor, and a large amount of Se vapor is vapor-deposited on the ceiling and openings of the Se vacuum vapor deposition chamber. For this reason, as the deposition proceeds, the moving path of the Se vapor is narrowed, and the shape of the moving path changes, so that the Se amount reaching the substrate surface also changes with time.

Therefore, the Se amount reaching the substrate is not constant in the main plane direction of the substrate, and also varies with time, so that the Se amount becomes non-uniform in the substrate surface and the large area CI
An S-based film cannot be obtained.

Therefore, the present inventors believe that this problem can be solved by changing the direction of the rotation axis of the rotating drum on which the substrate is mounted and the arrangement of the vacuum evaporation source, and provide the following manufacturing apparatus. .

First, the structure of a compound thin film manufacturing apparatus according to the present embodiment will be described with reference to FIGS.

The manufacturing apparatus according to the present embodiment comprises a cylindrical main vacuum chamber 1 having a plurality of (here, four) openings on the outer periphery, and one evaporation chamber 2 for vapor deposition connected to the openings.
And three sputtering chambers 3 (FIGS. 1 and 2). A rotating drum 5 is arranged inside the vacuum chamber 1 so as to keep a constant distance from the inner wall of the vacuum chamber 1. The rotating drum 5 rotates around the rotating shaft 4.

In this embodiment, the rotating drum 5 and the main vacuum chamber 2 are arranged so that the rotating shaft 4 is horizontal. And it is characterized in that the evaporation chamber 2 is arranged at the bottom of the main vacuum chamber 1.

A plurality of (four in FIG. 1 and FIG. 2) substrate mounting cassettes 8 for mounting substrates 7 are provided on the rotating drum 5. The evaporation chamber 2 and the three sputtering chambers 3 are independent of the vacuum chamber 1, respectively.
A shutter 1 that can be opened and closed
9 are arranged.

As can be seen from FIGS. 1 and 2, the shape of the evaporating chamber 2 is long in the axial direction of the rotating shaft 4 and its width is small. An evaporation source container 103 and a heater 102 for heating the evaporation source container 103 are provided at the bottom of the evaporation chamber 2, from which the steam 11 is discharged to the main vacuum chamber 1. Evaporation source container 103
Has a shape that is long and narrow in the axial direction of the rotating shaft 4,
Se is set therein as the evaporation source 10. Also,
A target holder 10 is provided at the bottom of the three sputtering chambers 3.
1 are arranged and hold the metal target 13.

The Se evaporation chamber 2 and the sputtering chamber 3 are connected to a vacuum exhaust system 9 respectively. Thereby, the Se evaporation chamber 2 and the sputtering chamber 3 together with the main vacuum chamber 1 can be made high vacuum. In the sputtering chamber 3,
Further, sputter gas inlets 12 are respectively connected to allow sputter gas such as argon gas to be introduced, and sputter particles 14 are emitted by sputtering the metal target 13. A substrate heating device 15 is installed inside the rotating drum 5 so that the substrate 7 can be heated. The measurement and control of the temperature of the substrate 7 can be performed by a substrate temperature monitor 16 installed between the substrate heating device 15 and the rotating drum 5. Further, as shown in FIG. 1, a substrate exchange load lock mechanism 17 is connected to a side surface of the main vacuum chamber 1 so that the substrate cassette 8 can be taken out without breaking vacuum. A large load lock mechanism 18 for exchanging the rotary drum 5 is connected to the side surface on the opposite side of the main vacuum chamber 1. Therefore, replacement of the substrate 7
In addition to the method of taking the substrate cassette in and out through the load lock mechanism 18, the entire rotary drum 5 can be taken out in the axial direction of the rotary shaft 4 by the large load lock mechanism 18.

In the present embodiment, since the Se evaporation chamber 2 is disposed on the bottom side of the main vacuum chamber 1, the S
When the liquid surface 6 of the e-melt becomes horizontal due to gravity, the melt surface 6 becomes parallel to the rotation axis 4. Therefore, when the substrate 7 attached to the cassette 8 of the rotary drum 5 passes above the Se evaporation chamber 2 due to the rotation of the rotary drum 5, the substrate 7 becomes parallel to the melt surface 6. Therefore, the melt surface 6 and the substrate 7
Is constant everywhere along the axial direction of the rotating shaft 4, so that the concentration of Se vapor is also constant along the axial direction of the rotating shaft 4. Therefore, by rotating the rotating drum 5, the Se vapor 11 having a constant concentration distribution can be supplied to the large-area substrate 7, and a large-area CIS film can be formed.

Next, a method of manufacturing a compound thin film using the above-described manufacturing apparatus will be described. Here, Cu, In, and S, such as a CuInSe ₂ thin film having a chalcopyrite structure and a CuIn ₃ Se ₅ thin film having a defect stannite structure, are used.
The case where a compound thin film containing e as a constituent element is formed on a substrate will be described as an example. In the present embodiment, Cu
A compound thin film containing In, Se, and In as constituent elements is referred to as a CIS thin film.

The Se evaporation source 10 in the evaporation chamber 2 is
A linear evaporation source (linear evaporation source) having a length of 120 cm in the direction of the rotating shaft 4 and a small width is used. A Cu target was attached as a target 13 to one of the three sputtering chambers 3, and a target 1 was placed in another sputtering chamber 3.
As No. 3, an In target is attached. The Cu target 13 and the In target 13 also have a length of 1 in the rotation axis 4 direction.
Use a 20 cm one.

The substrate 7 is 100 cm × 3 here.
A glass substrate of 0 cm is used. Then, the cassette is attached to the cassette 8 so that the longitudinal direction thereof coincides with the direction of the rotating shaft 4, and the cassette is attached to the rotating drum 5
To load. After loading, the evacuation system 9 evacuates the sputtering chamber 3, the evaporation chamber 2, and the main vacuum chamber 1. Further, the temperature of the substrate 7 is raised to a predetermined temperature by the substrate heating device 15. With all the shutters 19 closed, the heater 102 is heated to raise the temperature of the Se evaporation source 10. In the sputtering chamber 3, the target 1
3, a sputtering gas such as argon gas is introduced from a sputtering gas inlet 12 into a sputtering chamber 3 in which a Cu target and an In target are mounted, and further, a voltage is applied to the target holder 101 so that a metal target 13 is formed.
Causes discharge. Metal target 1 in sputtering chamber 3
When the discharge of 3 and the amount of Se evaporation in the evaporation chamber 2 are stabilized, the shutter 7 is opened while rotating the rotary drum 5 at a predetermined rotation speed.
Sputtered particles 14 jumping out of the metal target 13 adhere to the substrate 7 to form a film when passing in front of the substrate 7. When the substrate 7 passes in front of the evaporation chamber 2, Se vapor 11 adheres to the substrate 7. Then, selenization of the metal film on the substrate 7 occurs.

FIG. 6 shows a CIS thin film growth model by continuous sputtering and selenization by the manufacturing apparatus shown in FIGS. FIG. 6A shows a method of completing film formation and selenization by slowly rotating the rotary drum 5 once. In this method, the substrate 7 passes through the front of the sputtering chamber 3 of the Cu target 13 and the front of the sputtering chamber 3 of the In target 13 by rotating the rotating drum 5 slowly. Cu film 60
1. The In film 602 is stacked. Next, when the substrate 7
e Passing in front of the evaporation chamber 2, Se vapor is supplied and C
The u film 601 and the In film 602 are selenized. Since the substrate 7 is heated by the substrate heating device 15, C
A thermal diffusion reaction also occurs between the u film 601 and the In film 602, whereby a CIS thin film can be formed.
This method is the same as the conventional selenization method.

On the other hand, FIG. 6B shows a CIS thin film growth model by the continuous sputtering / selenization method of the present embodiment in which sputtering and selenization are repeated. In this method, the rotation speed of the rotating drum 5 is increased,
The substrate 7 passes through the sputtering chamber 3 of the Cu target 13, the sputtering chamber 3 of the In target 13, and the Se deposition chamber 2 in order at high speed. As a result, a Cu thin layer 604 and an In thin layer 605 are formed on the substrate 7, and then, when passing through the Se evaporation chamber 2, are selenized by Se vapor and a thin CIS thin film is formed by a thermal diffusion reaction. Becomes In the next rotation, the Cu thin layer 604 is again placed on the CIS thin film.
An In thin layer 605 is formed and further selenized to form a CIS thin film having twice the thickness. This method uses a rotating drum 5
This process is repeated each time one rotation is made, and by setting how many rotations of the rotating drum 5, a CIS thin film having a desired film thickness can be obtained. The method of FIG. 6C further increases the rotation speed compared to the method of FIG.
This is a method in which the thicknesses of the formed Cu thin layer 607 and In thin layer 608 are in the order of atoms, and the CIS film is laminated every time the rotating drum 5 makes one rotation.
Same as (b).

In any of the methods shown in FIGS. 6A to 6C, in the manufacturing apparatus of the present embodiment, the In and Cu films are formed by the sputtering method. By using a long target, an In layer and a Cu layer can be formed with a uniform thickness over a large-area substrate. Moreover, in the manufacturing apparatus of the present embodiment, Se is supplied as steam from the evaporation chamber 2 below the rotary drum 5, so that Se vapor can be supplied at a uniform concentration in the main plane direction of these substrates. The In layer and the Cu layer can be uniformly selenized in the in-plane direction. Further, by controlling the power supplied to the metal target 13 and controlling the supply amounts of Cu and In, the composition of the CIS thin film to be formed can be controlled. As a result, a CuInSe ₂ thin film having a chalcopyrite type structure and a CuI
An n ₃ Se ₅ thin film can be formed.

Further, since Se is supplied by vapor, a large-area, high-quality CIS-based film can be obtained without damage to the film surface due to Se negative ions or the like as in the conventional sputtering method. Further, since the sputtering chamber 3 and the Se evaporation chamber 2 are independent, the possibility that the sputter target is contaminated with Se is low.

Further, the manufacturing apparatus of the present embodiment is similar to that of FIG.
Since the rotating drum 5 can be rotated at a high speed as in (b) and (c), the thin Cu thin layers 604, 607,
A film formation method in which the steps of laminating the In thin layers 605 and 608 and selenizing them are repeated. For this reason, unlike the conventional selenization method, there is no rapid volume expansion due to selenization, and the problem of a decrease in voids and adhesion of the film as in the conventional method can be avoided.

Further, since the supply amounts of Cu and In can be controlled by controlling the power supplied to the metal target 13, the composition of the CIS thin film to be formed can be controlled, and a film having a desired composition can be obtained. be able to.
Moreover, by setting a Ga target in another sputtering chamber 3 and controlling the supply amounts of Cu, In, and Ga to the substrate, a method similar to the conventional three-step method can be performed, and the forbidden band width is reduced. Inclined graded band gap C
It is possible to form an IGS film. That is, a Cu target, a Ga target, and an In target are set as the metal targets 13 of the three sputtering chambers 3, respectively. Cu sputter particles, Ga sputter particles, and Se sputter particles are used as the first stage of film formation. The irradiation substrate is irradiated with Cu sputtered particles and Se vapor as a second stage, and In sputtered particles, Ga sputtered particles and Se vapor are irradiated as a third stage. This makes it possible to obtain a chalcopyrite-type Cu (In _1-x Ga _x ) Se ₂ (CIGS) film (x = 0 to 1) having a large grain size and excellent crystallization. Note that Ga
Has a low melting point, so Cu-G
It is also possible to use the target of the a alloy.

As described above, the manufacturing apparatus according to the present embodiment
An independent sputtering chamber 3 and an evaporating chamber 2 are attached around the main vacuum chamber 1, and the rotating drum 5
The rotary shaft 4 is horizontal, and the evaporating chamber 2 is
In the main plane direction of the substrate.
Steam can be supplied uniformly, and a high-quality, large-area CIS-based thin film can be manufactured.

In the present embodiment, Se is evaporated by the evaporation chamber 2 to form a compound thin film (CIS thin film) containing Cu, In and Se as constituent elements, and Cu, In and G
Although the formation of a compound thin film containing a and Se as constituent elements has been described, the manufacturing apparatus of the present embodiment is not limited to manufacturing these films, but is suitable for forming a compound thin film containing a low melting point metal. Can be used. In particular, it is suitable for forming a film of a chalcogen compound which is a low melting point material. Further, a compound containing a low-melting-point metal, which is preferably used for forming a film containing a low-melting-point metal that generates negative ions when the low-melting-point metal is sputtered. Examples of the metal (material) that generates a negative ion include an anion (anion) element and an element having a high electron affinity, or a compound thereof. Such a low-melting-point metal is vaporized by the evaporation chamber 2 of the manufacturing apparatus of the present embodiment, and another constituent metal is formed by sputtering from a sputtering chamber, whereby a high-quality film of the compound containing the low-melting-point metal is formed. Can be formed.

The substances that can be suitably formed into a film by the manufacturing apparatus of the present embodiment are shown below.

(1) Substance containing an element, compound or alloy which becomes a liquid phase at room temperature or becomes a liquid phase upon heating (2) Chalcogen compound (compound containing S, Se, Te) II-VI compound: ZnS, ZnSe, ZnTe , CdS, CdSe, CdTe, etc. I-III-VI Group ₂ compounds: CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) S
e ₂ , CuInS ₂ , CuGaSe ₂ , Cu (In, Ga) (S, Se) ₂ etc.I-III ₃ -VI Group ₅ compounds: CuIn ₃ Se ₅ , CuGa ₃ Se ₅ , Cu (In, G
a) ₃ Se ₅ etc. (3) Compound having chalcopyrite structure and compound having defective stannite structure I-III-VI group ₂ compound: CuInSe ₂ , CuGaSe ₂ , Cu (In, Ga) S
e ₂ , CuInS ₂ , CuGaSe ₂ , Cu (In, Ga) (S, Se) ₂ etc.I-III ₃ -VI Group ₅ compounds: CuIn ₃ Se ₅ , CuGa ₃ Se ₅ , Cu (In, Ga)
Such as ₃ Se ₅ However, in the above description, (In, Ga), ( S, Se) , _{respectively, (In 1-x Ga x} ), (S 1-y Se y) ( where x = 0 to 1,
y = 0 to 1).

When these compounds are formed into a film by the manufacturing apparatus of the present embodiment, a material to be melted such as chalcogen such as Se, S, Te or the like is supplied as vapor by the evaporation chamber 2 and other constituent materials are supplied. Since a film can be formed by sputtering in the sputtering chamber 3, a high-quality film can be formed.

[0048]

An embodiment of the present invention will be described below. In this embodiment, the structure is the same as that of the manufacturing apparatus shown in FIGS. 1 and 2 except that a small manufacturing apparatus in which the size of the metal target 13 and the evaporation source 10 is reduced is used, and a chalcopyrite-type CuInSe is used as the CIS thin film. _Two thin films were formed.

In the present embodiment, a disk target of high-purity copper having a diameter of 6.5 cm and a disk target of indium (purity 99.9999%) are used as the metal targets 13. The upper surface of the evaporation source 10 is also 6.5 c in diameter.
m high-purity Se (purity 99.999%) was used. The metal target 13 was sputtered by a direct current (DC) magnetron method. The distance between the target 13 and the substrate 7 is 6.
It was 5 cm. The substrate 7 is a glass substrate coated with a Mo film, and its size is 5 cm × 4 cm. In FIG. 2, four substrates 7 are attached to the rotating drum 5 by cassettes 8 respectively, but in the present embodiment, five substrates 7 are each attached to the stainless rotating drum 5 by the stainless steel cassette 8. Attached. As the substrate temperature monitor 16, a chromel-alumel thermocouple attached to the rotating drum 5 was used.

Film formation was carried out by such an apparatus as follows. First, the main vacuum chamber 1 is set to 10 ⁻⁶ Torr.
After evacuating to a vacuum, high-purity argon gas (99.99
9%) was introduced into the sputtering chamber 3 from the sputter gas inlet 12 and adjusted by a variable leak valve to 3 × 10 ⁻² Torr. Before depositing the CIS film,
n target 13 is sputtered and has a thickness of about 50 nm at room temperature.
Was formed on the substrate 7 with the Mo film to improve the adhesion of the CIS film. Next, a CIS film was deposited.
Specifically, each metal target 13 in the sputtering chamber 3 was sputtered, the Se evaporation source 10 in the Se evaporation chamber 2 was heated, and the shutter 19 was opened. During deposition of the CIS film, the temperature of the substrate 7 was kept constant at 450 ° C. The rotation speed of the rotating drum 5 was set to an arbitrary rotation speed between 0 and 100 rpm, and the linkage between the rotation speed and the crystallographic properties of the formed film was examined. Further, the input current to the Cu and In targets 13 is controlled to control the properties of the CIS thin film.
The atomic ratio was controlled. Further, the atomic ratio of Se / (Cu + In) was kept at least twice in order to prevent re-evaporation of Se.
Under such conditions, a typical film deposition rate was 150 Å / min. In this embodiment, since a small device is used, the target 13 and the input power are small, and the film deposition speed is such a low speed. However, by using a larger metal target 13 and increasing the input power, It is possible to get a practical speed.

Under these conditions, the rotation speed of the rotary drum 5 is reduced to 0 rpm (that is, each metal target 13 and Se
The substrate is stopped before the evaporation source 10), 40 rpm, 1
CIS films were formed at three different speeds of 00 rpm. At this time,
The contamination of the metal target 13 which was a problem in the ordinary hybrid sputtering method did not occur, and a stable discharge during sputtering was confirmed.

FIGS. 3 (a), 3 (b) and 3 (c) respectively show
The rotation speed of the rotating drum 5 is 0 rpm, 40 rpm as described above.
FIG. 4 is a sketch drawing of an SEM (scanning electron microscope) observation image of a CIS thin film grown on a Mo film / glass substrate 7 at m, 100 rpm. 3 (a), 3 (b),
The Cu / In ratio of the CIS thin film of (c) was estimated by X-ray fluorescence analysis to be 0.93 in all cases. C
When the u / In ratio is 0.93, a thin film of a CuInSe ₂ crystal having a chalcopyrite structure partially containing vacancies is obtained. Actually, when the CIS thin films of FIGS. 3A, 3B, and 3C were examined by X-ray diffraction, as shown in FIG. , 1
03 and 211 diffraction lines appeared, and it was confirmed that these films were CuInSe ₂ thin films having a (112) -oriented chalcopyrite structure.

As can be seen from FIGS. 3A, 3B, and 3C, the surface morphology greatly depends on the speed of the rotating drum 5. For example, when the speed of the rotating drum 5 is 0 (FIG. 3A), ie, the Se film (240 nm) / C
When laminated in the order of u film (120 nm) / In film (50 nm) / Mo film / glass substrate 7, the same state as the conventional selenization method is realized. Therefore, the CIS thin film was separated from Mo due to rapid volume expansion. Next,
When the rotation speed of the rotating drum 5 is 40 rpm (FIG. 3
(B)) Although the peeling of the film is eliminated, the crystal grains are small and the crystal growth is not sufficient. On the other hand, when the rotation speed of the rotating drum 5 was 100 rpm (FIG. 3C), the development of crystal grains was observed. As described above, the increase in the number of rotations of the rotating drum 5 improves the crystallinity by intermittently causing atoms to enter the surface of the substrate 7 as shown in FIG.
This is presumed to be because atoms can migrate sufficiently on the surface. Also, at this time, the extremely thin Cu layer / In layer is selenized to form a CIS layer, and the same process is further continued thereon. It is not observed in the CIS film of c).

On the other hand, the rotational speed of the rotary drum 5 is set to 100 r.
pm, the current applied to the Cu and In targets 13 is controlled, and the Cu / I
5 shows an SEM photograph of a CIS thin film when the n atomic ratio is changed. FIG. 4A shows a CIS film (Cu
/In=1.09) and FIG. 4 (b) shows a CIS film having a nearly stoichiometric composition (Cu / In = 0.93).
(C) shows a CIS film (Cu / In =
0.86). Note that the Cu / In atomic ratio is 0.86
The CIS film in the range of ~ 1.09 is a CuInSe ₂ thin film having a chalcopyrite structure. In the Cu-rich CIS film of FIG. 4A, particularly, growth of large crystal grains is observed.
This is thought to be due to the liquid phase sintering process using liquid phase Cu _2-x Se (x = 0 to 1).

Next, a solar cell was prepared using these CIS thin films as a light absorbing layer. The battery structure, from the light incident side,
ZnO: Al film / CdS film / CIS film / Mo film / soda lime glass substrate 7 The manufacturing procedure of this battery will be briefly described. First, a molybdenum film is formed as a lower electrode on a soda lime glass substrate 7 by sputtering to a thickness of 0.8 μm.
m, and a CIS thin film having a thickness of about 2 μm is formed thereon by the manufacturing apparatus of this embodiment. Next, as a buffer layer,
A CdS thin film was deposited to a thickness of about 90 nm by a solution growth method, and a ZnO: Al film as a transparent conductive film was formed thereon by RF sputtering to a thickness of 0.6 μm. Finally, an Al grid electrode was formed as an upper electrode by a vapor deposition method.

The output characteristics of the solar cell manufactured as described above were measured with a solar simulator of AM 1.5 and 100 mW / cm ² , and as a result, the open voltage was 440 mV, the short circuit current was 34 mA / cm ² , the fill factor was 0.69, and the intrinsic property was 0.69. A conversion efficiency of 10.3% was obtained.

As a result of these series of experiments, continuous sputtering /
It was confirmed that the solar cell grade CIS film can be formed by the selenization method. In addition, it was found that contamination of the metal target 13 by Se, which had been a problem in hybrid sputtering at the time of film formation, could be reduced, stable discharge could be ensured, and generation of voids of μm size, which had been a problem in the selenization method, could be suppressed. Was.

In this embodiment, the evaporation source 10 is S
Although e is used to supply Se vapor, any evaporation source that can supply Se vapor may be used. For example, a Se compound may be used.

[0059]

As described above, according to the present invention,
A compound thin film manufacturing apparatus capable of manufacturing a high-quality, large-area CIS-based thin film can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an apparatus for manufacturing a compound thin film according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line A-A 'of the manufacturing apparatus of FIG.

FIG. 3 shows the rotational speed of the rotary drum 5 in the manufacturing apparatus of FIG.
rpm of chalcopyrite structure formed at rpm
The figure which sketched the SEM observation image of the upper surface of S thin film.

FIG. 4 (a) Cu / In = film formed by the manufacturing apparatus of FIG.
1.09 chalcopyrite type CIS thin film,
(B) SEM of top and cross section of CIS thin film of chalcopyrite type structure with Cu / In = 0.86 and (c) chalcopyrite type structure of Cu / In = 0.86.
The figure which sketched the observation image.

FIG. 5 is a graph showing the X-ray diffraction peaks of the CIS films of FIGS. 3 (a), (b) and (c).

6 (a), (b), (c) are explanatory views showing the configuration of a film formed on a substrate 7 in the manufacturing apparatus of FIG.

[Explanation of symbols]

1 ・ ・ ・ Main vacuum chamber, 2 ・ ・ ・ Se evaporation chamber, 3 ・
..Sputter chamber, 4 ... rotary axis, 6 ... Se melt surface, 7 ... substrate, 8 ... substrate cassette, 9 ...
Vacuum exhaust system, 10: Se evaporation source, 11: Se vapor, 12: Sputter gas inlet, 13: Metal target, 14: Sputter particles, 15: Substrate heating device, 16: substrate temperature monitor, 17: load lock mechanism, 18: large load lock mechanism, 19
... Shutter, 101 ... Target holder,
102: heater, 103: evaporation source container.

Claims (5)

[Claims] 1. A main vacuum chamber having a plurality of openings around the periphery, a rotating drum disposed in the main vacuum chamber for mounting and rotating a substrate on an outer periphery, and sputter particles from the opening toward the substrate. Having at least one sputter chamber attached to said opening, and at least one vacuum evaporation chamber attached to said opening to supply vapor from said opening to said substrate; The rotating drum is arranged so that a rotation axis is horizontal, and one of the plurality of openings is provided at a bottom of the main vacuum chamber, and the vacuum evaporation chamber is provided at an opening provided at the bottom. An apparatus for producing a compound film, wherein the apparatus is attached. 2. The manufacturing apparatus according to claim 1, wherein the vacuum evaporation chamber includes an evaporation source container for holding an evaporation source, and the evaporation source container is disposed at a bottom of the vacuum evaporation chamber. Characteristic compound film manufacturing equipment. 3. The manufacturing apparatus according to claim 2, wherein the shape of the opening to which the vacuum evaporation chamber is attached and the shape of the upper surface of the evaporation source container are both parallel to the rotation axis direction of the rotary drum. An apparatus for producing a compound film, wherein the length in the direction is longer than the length in the width direction. 4. A rotary drum having a substrate mounted on its outer periphery is disposed and rotated in a vacuum chamber so that a rotation axis is horizontal, and Se is heated in an evaporation chamber mounted on an opening at the bottom of the vacuum chamber. , Se vapor is supplied to the rotating drum, and at least sputter particles of In and Cu are supplied to the rotating drum from a sputtering chamber attached around the vacuum chamber, so that Cu, In, and Se are supplied. Forming a compound film on the substrate, the method comprising: 5. A rotary drum having a substrate mounted on an outer periphery thereof is arranged and rotated in a vacuum chamber so that a rotation axis is horizontal, and heated in an evaporation chamber mounted on an opening at the bottom of the vacuum chamber to obtain a melt. By heating the substance to be, and supplying the vapor of the substance toward the rotating drum, by supplying sputtered particles of the metal element from the sputtering chamber attached around the vacuum chamber toward the rotating drum, A method of manufacturing a compound film, comprising forming a compound film of the metal element and the substance on the substrate.