JP2002203800A - Wafer cassette, device using the same and liquid phase growth method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provided a method and a device for preventing the growth of a film at the entire rear and side surfaces of an Si wafer and at peripheral section of a surface. SOLUTION: The device dips the Si wafer 6 supported by tools 21, 24 and 25 into a solvent 4, and grows a film on the Si wafer 6 due to liquid phase growth from the solvent. Wafer cassettes 21, 22, 23, 24, 25 and 30 have a counter sink (recess) 31 corresponding to the shape of the Si wafer 6, and have a wafer- backing pedestal (retention member) 25 for fitting the Si wafer 6 to the counter sink (recess) 31 and a wafer cover (cover) 24 where an opening 27 on a smaller surface than the Si wafer 6 is opened. The Si wafer 6 is pressed at the peripheral section. In this case, a plurality of wafer-backing pedestals (retention members) 25 is available, is arranged in parallel, and is supported by a post 21. A groove 28 is present at the connection section with the wafer-backing pedestals (retention members) 25 of the post 21, and the wafer cover (cover) 24 is fitted to the groove 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer cassette,
The present invention relates to a liquid phase growth method and a liquid phase growth apparatus, and more particularly to an immersion type liquid phase growth method and a liquid phase growth apparatus in which a wafer-sized substrate is held by a jig and is immersed in a solvent.

[0002]

2. Description of the Related Art Emission of global warming gases such as carbon dioxide and nitrogen oxides due to the burning of petroleum by thermal power generation and the burning of gasoline by automobile engines cause deterioration of the global environment. In the future, there is concern about depletion of crude oil, and there is increasing interest in solar cell power generation as a clean energy source.

A thin-film crystalline silicon (Si) solar cell has a thin power generation layer and uses a small amount of Si material, so that the cost can be reduced. In addition, since the power generation layer is made of crystalline Si, higher conversion efficiency and lower deterioration can be expected as compared with a solar cell made of amorphous Si or the like. Furthermore, since the thin-film crystalline Si solar cell can be bent to some extent, it can be used by sticking it on a curved surface of an automobile body, a home appliance, a roof tile, or the like.

In order to realize this thin-film crystalline Si solar cell,
Japanese Patent Application Laid-Open No. 8-213645 discloses that a porous Si layer is
To CVD (Chemical Vapor Depos)
using an epitaxial layer grown by
Discloses that a thin film single crystal Si is separated. Figure
Reference numeral 18 denotes Japanese Patent Application Laid-Open No. 8-213645, and
It is sectional drawing showing the method of forming a solar cell. In the figure, 1
01 is a Si wafer, 102 is a porous Si layer, 103 is p
⁺Type Si layer, 104 is p^-Type Si layer, 105 is n ⁺Type S
i layer, 106 is a protective film, 109 and 111 are adhesives, 11
Numerals 0 and 112 are jigs. Method for manufacturing solar cell of FIG.
Then, the surface of the Si wafer 101 is made porous by anodization.
An Si layer 102 is formed. Then, the porous Si layer 102
P on⁺Type Si layer 103 is epitaxially grown,
And p on it^-Type Si layer 104 and n⁺Type Si layer 105
Grow. Then, a protective layer 106 is formed. Soshi
To the protective layer 106 and the Si wafer 101, respectively.
Attach to the jigs 112 and 110 with the agents 111 and 109
Let Thereafter, a pulling force P is applied to the jigs 110 and 112.
The porous Si layer 102 and the Si wafer 101
The axial Si layers 103, 104, 105 are separated.
Then, the epitaxial Si layers 103, 104, 105
A solar cell is formed in the
To reduce costs.

[0005] Also, Japanese Patent Application Laid-Open No. 5-283722 discloses that
It discloses that an epitaxial Si layer is grown on a porous Si layer by a liquid phase growth method. Sn is used as a solvent, and Si is previously dissolved in Sn and saturated before growth. Next, slow cooling was started, and when a certain degree of supersaturation was reached, the porous surface of the wafer was immersed in a Sn solution.
An epitaxial Si layer is grown on the porous surface.

Japanese Patent Application Laid-Open No. Hei 10-189924 discloses that a liquid-phase grown epitaxial layer is formed on a porous Si surface.
It discloses growing a layered wafer and stripping the epitaxial layer to produce a solar cell.

Japanese Patent Application Laid-Open No. 10-053488 discloses a solvent injection type liquid phase growth apparatus in which a jig having no deposited film on the back and side surfaces of a wafer is disclosed. However, the liquid phase growth apparatus disclosed in Japanese Patent Application Laid-Open No. H10-53488 is of a solvent injection type, and therefore has a disadvantage that the growth apparatus becomes large-scale when growing on a large number of wafers. In addition, in order to cope with a large-diameter wafer such as 8 inches or more, the liquid phase growth apparatus becomes larger, and this disadvantage becomes more remarkable.

Japanese Patent Laid-Open No. 5-17284 discloses an immersion type liquid phase growth apparatus for compound semiconductors and a holding jig. FIG. 19 is a sectional view of this liquid phase growth apparatus.
In the figure, 81 is a wafer holder, 82 is a wafer, 83 is a crucible, 84 is a solvent, 85 is a quartz reaction tube, 86 is a gas introduction tube, 87 is a gas discharge tube, 88 is a heater, and 89 is a dummy wafer. In this immersion type liquid phase growth apparatus, a wafer holder 81 holding a wafer 82 and a dummy wafer 89 is provided.
Is lowered (in the direction A), so that the wafer 82 is immersed in the solvent 84 in which the growth material is dissolved. Solvent 8
4 is in a crucible 83, and the crucible 83 is a quartz reaction tube 8 which is maintained in an atmosphere of an atmosphere gas (a reducing gas or an inert gas) by using a gas introduction pipe 86 and a gas discharge pipe 87.
Place in 5. The heater 88 is for controlling the temperature of the system. By lowering the temperature of the heater 88, the temperature of the solvent 84 is reduced, and a growth material is deposited on the wafer 82 from the solvent 84 to perform liquid phase growth. The size of the immersion type liquid phase growth apparatus can be smaller than that of the slide board type or solvent injection type liquid phase growth apparatus for liquid phase growth on wafers of the same size. Also, since a large number of wafers can be arranged in the holder, it is convenient for mass production.

When it is desired to grow a deposited film only on the front surface of a wafer as in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-213645, the deposited film should not be grown on the back surface, the side surface and the peripheral portion of the front surface of the wafer. Want to. However, when the wafer is immersed in a solvent and grown in a liquid phase growth apparatus disclosed in JP-A-5-17284 as shown in FIG. 19, the deposited film grows not only on the front surface of the wafer but also on the back surface and side surfaces. I will. For this reason, when it is desired to use a deposited film only on a desired surface, the deposited film on the back surface, side surface, or peripheral portion of the surface must be cut off or etched, which not only causes an increase in the number of steps but also increases the yield. Will be lowered.

Further, according to the wafer holder disclosed in Japanese Patent Application Laid-Open No. Hei 10-53488, although liquid phase growth on a part of the back surface and the side surface can be prevented, there is a problem that a part of the side surface grows.

Also, as disclosed in Japanese Patent Application Laid-Open No. 10-189924, when it is desired to separate a liquid-phase-grown epitaxial layer from a wafer as a thin-film single-crystal layer, the peripheral portion of the surface becomes too thick or not thick. Also porous S around
Separation may not be successful at the periphery due to the instability of the i-layer.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wafer cassette, a liquid phase growth method and a liquid phase growth apparatus for preventing film growth on the entire back surface and side surfaces of the wafer and on the peripheral portion of the surface. That is. In particular, the object of the present invention is to:
An object of the present invention is to provide a liquid phase growth method and a liquid phase growth apparatus which can be suitably used for immersion type liquid phase growth which is advantageous for increasing the size and mass production of wafers.

[0013]

For this purpose, the present inventors have made intensive efforts and have obtained the following invention.

That is, the wafer cassette of the present invention is a wafer cassette for holding a substrate having a concave portion corresponding to the shape of a substrate and a substrate having a cover having an opening smaller than the surface of the substrate. And the cover holds the substrate in the recess, and one surface and side surfaces of the substrate and all peripheral portions of the other surface,
It is characterized by being covered by an edge of the opening of the cover and the concave portion of the holding member.

Further, the liquid phase growth apparatus of the present invention is a liquid phase growth apparatus for growing a film on a substrate in a liquid phase, wherein the liquid phase growth apparatus includes a transfer system for transferring the wafer cassette.
And a crucible holding a solvent, wherein the transport system comprises:
The wafer cassette is transferred to the crucible.

Further, the liquid phase growth method of the present invention is a method for liquid phase growth of a film on a substrate, wherein the wafer cassette holding the substrate is immersed in a solvent,
Reducing the temperature of the solvent.

Here, it is preferable that there are a plurality of the holding members, which are arranged in parallel and supported by columns. In addition, there is a groove in the connecting portion of the support and the holding member,
The cover and the substrate may be held by fitting the cover into the groove. Preferably, the cover is rotated in parallel with the holding member, and the cover is fitted in the groove. Further, the cover includes a stopper for preventing the cover from rotating by contacting the support, and during the growth of the deposited film, the holding member is rotated so as to fix the cover using the stopper. It is better to let. Further, it is preferable to use a substrate having a porous surface as the substrate.

Other features of the present invention will be described later in detail with reference to the specification and the drawings.

[0019]

Embodiments of the present invention will be described in detail with reference to the drawings. Four embodiments will be described.
Not only in each embodiment, but also in each combination is within the scope of the present invention.

Embodiment 1 The wafer cassette according to Embodiment 1 has four wafer backing pedestals for holding wafers, supports the wafers on both sides of the wafer backing pedestals, and supports each wafer backing pedestal with a wafer backing pedestal. It is made of monolithic quartz. FIG. 1 is a cross-sectional view of the wafer cassette according to the first embodiment as viewed from the side, and FIG. 2 is a cross-sectional view of the wafer cassette taken along line DD ′ in FIG. The cross section taken along the line CC 'in FIG. 2 corresponds to the cross section viewed from the side in FIG. In the figure, 68 is a wafer cassette, 21 is a support,
Reference numeral 22 denotes a nut, 23 denotes a threaded portion, 24 denotes a wafer cover (also referred to simply as a cover, the same applies hereinafter), 25 denotes a wafer backing pedestal, 30 denotes a column supporting disk, and
It is made of quartz to withstand a temperature of about 0 ° C. Reference numeral 6 denotes a Si wafer (also referred to as a substrate; the same applies to the following) having an orientation flat (hereinafter, abbreviated as an orientation flat) at a position 29 in FIG. A counterbore (also referred to as a concave portion) in a wafer backing pedestal (also referred to as a holding member; the same applies hereinafter) 25.
The same applies hereinafter. ) An Si wafer is buried in 31 and held using a wafer cover 24.

FIG. 3 is a sectional view similar to FIG. 2 when the wafer cover 24 is removed from the wafer backing pedestal 25 shown in FIG. The wafer backing pedestal 25 has a diameter of 0.1 to
The orientation flat portion 2 of the Si wafer 6 is about 0.5 mm larger.
A counterbore 31 conforming to the shape of 9 is provided, and the Si wafer 6 is embedded in the counterbore 31. Therefore, the wafer backing pedestal 25 serves as a holding member for holding the Si wafer 6. The wafer cover 24 converts the Si wafer 6 into the Si wafer 6
2 has an inner diameter 1 to 5 mm smaller than that of the Si wafer 6 as shown in FIG.
Has an opening 27 corresponding to the shape. Also, as shown in FIG. 1, grooves 28
Are dug, and the wafer cover 24 is fixed by aligning the wafer cover 24 with the groove 28. When mounting or removing the wafer cover 24, the wafer cover 24 is rotated in the groove 28 so that the notch portion 26 shown in FIG.
To the support 21. With this structure, the Si wafer can be easily attached and taken out. Such a structure for fixing the Si wafer 6 is the same as the structure of the portion for holding the other Si wafer 6. The support 21 has a threaded portion 23 at the upper part, and penetrates a hole 32 of the support disk 30 and is fixed with a nut 22. Above, the support disk 30
And the nut 22 are also described as being made of quartz.
If 1 is fairly long and the temperature of nut 22 and strut support disk 30 can be kept below 500 ° C., a metal such as stainless steel may be used.

Hereinafter, the entire liquid phase growth method will be described using a manufacturing process of a thin film crystalline Si solar cell. FIG.
It is a perspective view of the completed thin film crystal Si solar cell. 1 is a front electrode, 2 is a back electrode, 3 is a glass substrate, 4 is an n ⁺ type S
The i layer 5 and the p ^- type Si layer 5 represent a p ^- type Si layer. 8 and 9 show cross sections of steps for manufacturing a solar cell having this structure. First, a single crystal Si wafer 6 is prepared as shown in FIG. Next, as shown in FIG. 8B, a porous Si layer 7 having a thickness of 1 to 30 μm is formed on the surface of the Si wafer 6 by anodization. Since the thickness of the Si wafer 6 is about 600 μm and the thickness of the porous Si layer 7 is about 1 to 30 μm,
Only the surface layer of the Si wafer 6 becomes the porous Si layer 7. Most of the Si wafer 6 remains as the non-porous Si layer 8.

FIGS. 10A and 10B are sectional views of an apparatus for anodizing the Si wafer 6 with a hydrofluoric acid-based etching solution. In the figure, 6 is a Si wafer, 11 is a hydrofluoric acid-based etching solution, 12 and 13 are metal electrodes, and 14 is an O-ring. The Si wafer 6 to be anodized is preferably of a p-type, but may be of an n-type if the resistance is low. In addition, even if an n-type Si wafer is irradiated with light to generate holes, it can be made porous. As shown in FIG. 10A, a voltage is applied between both electrodes by setting the lower metal electrode 12 to be positive and the upper metal electrode 13 to be negative. When installed in such a way that
The upper surface of the wafer 6 is made porous. FIG. 10 (b)
The left metal electrode 12 is positive and the right metal electrode 1 is
When the voltage is applied with the Si wafer 6 placed between both electrodes, the surface on the right side of the Si wafer 6, that is, the negative electrode side is made porous. As the hydrofluoric acid-based etching solution 11, concentrated hydrofluoric acid (for example, 49% HF) is used. Metal electrodes 12, 13
Pt, Au, or the like is used. During anodization, Si
Since air bubbles are generated from the wafer 6, alcohol may be added as a surfactant in order to efficiently remove the air bubbles. Methanol, ethanol, as alcohol
Desirable are propanol and isopropanol. Alternatively, anodizing may be performed while stirring using a stirrer instead of the surfactant. The thickness of the porous surface is
0.1-30 μm is good, and more preferably, 1-10 μm
m.

In the anodization step, the current flowing from the metal electrode 12 to the metal electrode 13 during the anodization is changed to facilitate separation in the separation step later. For example, a small current is applied in the initial stage of anodization for making the outermost layer of the Si wafer 6 porous, and a large current is applied in the final stage of anodization for making the vicinity of the interface between the non-porous Si layer 8 and the porous Si layer 7 porous. Apply current. Then, the surface layer in the porous Si layer 7 has a structure with small holes that facilitate the subsequent epitaxial growth, and the non-porous Si layer 8 side of the porous Si layer 7 has a structure with large holes that facilitate the separation. . As a result, the subsequent epitaxial growth step and separation step can be easily performed. Of course, for simplification of the process, anodization may be performed at a constant current.

Next, as shown in FIG. 8C, a p ^- type single crystal Si layer 5 is formed on the porous Si layer 7 by liquid phase growth to a thickness of 2.
After the growth of 0 to 50 μm, the n ⁺ -type single-crystal Si layer 4 is grown as shown in FIG. At this time, the back and side surfaces of the wafer 6 and the porous S
The p − -type single-crystal Si layer 5 and the n + -type single-crystal Si layer 4 do not grow on all peripheral portions of the surface of the i-layer 7. The step of growing the p ⁻ type single crystal Si layer 5 and the n ⁺ type single crystal Si layer 4 will be described in detail. FIG. 5 is a view of a two-tank type liquid phase growth apparatus as viewed from above. In the figure, 51 is a loading chamber (L / C), 52 is a hydrogen annealing chamber, 54 is a growth chamber for the p ⁻ type Si layer 5, 55 is a growth chamber for the n ⁺ type Si layer 4, and 56 is an unloading chamber. (UL / C) and 63 are cores into which the transfer system of the wafer cassette 68 enters. 58 and 59 are p ^- type Si, respectively.
Layer, n ⁺ -type Si layer of the transfer chamber for supplying Si source to the growth chamber, 61 and 62, respectively p ^- type Si layer, n ⁺
This is a storage room for the Si raw material for the growth chamber of the type Si layer.

When liquid phase growth is carried out, first, the surface is porous.
Cassette containing Si wafer 6 with porous Si layer 7
68 into the loading chamber (L / C) 51
You. Then, using the transport system in the core 63,
Cassettes in the loading chamber (L / C) 51
68 to the hydrogen annealing chamber 52,
Do. Thereafter, the wafer cassette 68 is p^-Type Si layer 5
Growth chamber 54, n ⁺Growth chamber for Si layer 4
55, and as shown in FIGS. 8 (c) and (d),
p^-Type Si layer 5, n⁺Type Si layer 4 as a table of porous Si layer 7
Form on the surface.

FIG. 6 is a sectional view taken along the line AA 'of FIG. In the drawing, 64 is a solvent, 65 is a heater, 66 is a crucible, 68 is a wafer cassette of the present embodiment, 69 is a vertical transfer system, 70 is a horizontal transfer system, 86 is a melt-in wafer cassette, and 87 is a melter. Reference numeral 38 denotes a connection portion. The parts with the reference numerals described above are the same as the parts described above, and the description is omitted. The loading chamber 51 is normally in a state of being isolated from the core 63 and the outside air by the gate valve 67. Loading chamber 5
In 1, the gate valve 67 on the right side of the loading chamber 51 is released, and the wafer cassette 68 can be introduced. By releasing the gate valve on the left side of the loading chamber 51, the wafer cassette 68 can be moved to the growth chamber 54 of the p ⁻ -type Si layer using the horizontal transfer system 70 in the core 63.

The Si raw material supply chamber 61 is configured such that the wafer cassette 86 can be taken in and out by opening the gate valve 67 on the left side. By releasing the gate valve on the right side, the melted wafer cassette 86 is moved to the p ⁻ type Si layer growth chamber 54 using the horizontal transfer system 70 in the transfer chamber 58.
It can be moved to. The p ^- type Si layer growth chamber 54 has a vertical transfer system 69 for moving the wafer cassette 68 and the melted wafer cassette 86 up and down. The vertical transfer system 69 can dissolve the wafer cassette 68 and the substrate cassette 86 into the solvent 64 stored in the crucible 66. The connection part 38 is composed of a wafer cassette 68 made of quartz and a vertical transfer system 6 made of stainless steel.
9 is connected. This connection is desirably a keyed connection. The heater 65 keeps the solvent 64 in a liquid state by applying a high temperature to the solvent 64. The cross sections of the n ⁺ -type Si layer growth chamber 55, the transfer chamber 59, and the Si source supply chamber 62 have the same structure as in FIG. As described above with reference to FIGS. 1 to 3, the solvent 64 does not touch the entire back surface and side surfaces of the Si wafer 6 and the periphery of the surface. No film growth on the part occurs. Therefore, a film can be grown only on a desired surface. The melt-in wafer cassette 86 converts S Si from one Si wafer into a solvent as much as possible.
The surface, the back surface, and the side surfaces are in contact with the solvent 64 so as to dissolve i. When growing, the vertical transport system 69
It is desirable to impart rotation to the wafer cassette 68 using.

FIG. 7 is a time chart showing a sequence for operating the liquid phase growth apparatus shown in FIGS. 5 and 6. A represents the movement of the wafer cassette of the first batch. The wafer cassette of the first batch is loaded into the loading chamber 51 in the first 20 minutes and transferred to the hydrogen annealing chamber 52. In the hydrogen annealing chamber 52, the temperature of the wafer cassette 68 is raised for 30 minutes, and hydrogen annealing is performed for 10 minutes. The hydrogen annealing is performed at about 1040 ° C. in a hydrogen atmosphere. Also, a slight amount of SiH ₄ (silane) gas may be flown immediately after the hydrogen annealing to improve the surface properties of the porous Si layer 7. Then, the wafer cassette 68 is moved to the growth chamber 54 of the p ⁻ -type Si layer while using the transfer system 20 in the horizontal direction of the core 63, and is held for 10 minutes until the wafer cassette 68 reaches the growth temperature. At this time, the solvent 64 is cooled, and the p ^- type Si in the solvent 64 becomes supersaturated. Before moving the wafer cassette 68 to the p ⁻ type Si layer growth chamber 54, the molten wafer cassette 86 holding a p ⁻ type Si wafer or the like is transferred from the Si source supply chamber 61 to the solvent 64 at a high temperature through the transfer chamber 58. Soak,
P ^- type Si is dissolved in the solvent 64. Solvent 64
Are In, Sn and the like.

Then, the wafer cassette 68 is immersed in the solvent 64 by using the vertical transfer system, and the temperature of the solvent 64 is gradually lowered. As a result, the p ^- type Si layer grows epitaxially on the surface of the porous Si layer 7. . This growth time is about 30 minutes.

Thereafter, the wafer cassette 68 is lifted up from the solvent 64 and moved to the n ⁺ -type Si layer growth chamber 55, kept for 10 minutes in the same manner, and a supersaturated liquid of n ⁺ -type Si is applied to the solvent 64. At this time, the melted wafer cassette holding the n ⁺ -type Si wafer in advance is immersed in the solvent 64, and the n ⁺ -type Si is dissolved in the solvent 64 for 20 minutes. When the wafer cassette 68 is immersed in the solvent 64 and the temperature of the solvent 64 is gradually lowered, the n ⁺ -type Si layer 4 grows epitaxially on the surface of the p ^-- type Si layer 5. This growth time is about 10 minutes.

Thereafter, the wafer cassette 68 is lifted up from the solvent 64, moved to the unloading chamber 56, cooled for 55 minutes and returned to room temperature, and then taken out of the liquid phase growth apparatus for the last 5 minutes. B is
The movement of the wafer cassette of the second batch is shown. The wafer cassette of the second batch is also moved in accordance with the time chart of FIG. 7, but the movement is the same as that of the wafer cassette of the first batch, and the description is omitted. According to the liquid phase growth apparatus of the first embodiment, the liquid phase growth of a new wafer cassette can be performed every 60 minutes.

The p ^- type Si layer 5 and the n ⁺ type S
After completion of the liquid phase growth of the i-layer 4, as shown in FIG. 8 (e) n ⁺
The surface electrode 1 is formed on the mold Si layer 4 by a method such as printing. The surface electrode 1 has a comb-like structure as shown in FIG. 4 which is a perspective view. Next, an antireflection film made of TiO (titanium oxide), MgF (magnesium fluoride), SiN (silicon nitride) or the like is formed on the n ⁺ -type Si layer 4 not covered with the surface electrode 1 by a method such as sputtering. Then, as shown in FIG. 9A, the glass substrate 3 is adhered thereon with an adhesive. At this time, care is taken so that the glass substrate 3 does not stick to the peripheral portion of the wafer where the liquid phase has not been grown.

Thereafter, the glass substrate 3 and the non-porous Si layer 8
A tensile stress acts between them to separate the non-porous Si layer 8 from the portion to be a solar cell at the portion of the porous Si layer 7. Since the glass substrate 3 is not attached to the epitaxial growth layers 4 and 5 at the peripheral portion of the wafer, there is no problem that only the peripheral portion remains without being separated in this separation step. The non-porous Si layer 8 is used for the step of FIG. 8A by removing the residual porous Si on the surface with an alkali etchant or the like and again forming the Si wafer 6. The part which becomes the solar cell separated in FIG.
The residue of the layer 7 is removed with an alkali etchant or the like to obtain a structure having no residue as shown in FIG. Then p
^A back electrode 2 made of stainless steel, Al steel plate, or the like is bonded to the back surface of the -type Si layer 5 with a conductive adhesive or the like, thereby completing a solar cell unit cell. P ^- type S of back electrode 2
The attachment to the i-layer 5 may be performed by heat welding.

When the immersion type liquid phase growth is performed using the wafer cassette of the first embodiment, the film does not grow on the back surface, the side surface, or the peripheral portion of the front surface of the wafer. Can be done. In the first embodiment, an example in which a porous Si layer is formed on a Si wafer and single-crystal Si is epitaxially grown has been described. However, a Ge or GaAs wafer may be used instead of a Si wafer. GaAs or the like may be grown on a porous Si layer obtained by anodizing a Si wafer.
Although an example of manufacturing a solar cell has been described, an epitaxial wafer or SOI (Silicon Insula) is used.
(tor) It may be applied to manufacture of a substrate.

Second Embodiment A wafer cassette according to the second embodiment has the same structure as the first embodiment.
There are four wafer backing pedestals that hold the i-wafer, and the pillars that hold the Si wafer on the front and back, support the respective wafer backing pedestals, and the wafer backing pedestals themselves are made of an integrated quartz structure. There is a department.
FIG. 11 is a cross-sectional view showing the structure of the wafer cover 24 according to the second embodiment as viewed obliquely from above. FIG. 11 corresponds to FIG. 2 of the first embodiment. The difference from the first embodiment described with reference to FIG.
That is, the wafer cover 24 has four stopper portions 33. Other component codes are the same as in the first embodiment.
The stopper portion 33 has an effect of further fixing the wafer cover 24 to the wafer backing pedestal 25. In the second embodiment, when the wafer cassette is rotated in the direction of arrow B in FIG. 11 during the liquid phase growth, for example, the wafer cover 24 is
Even if the wafer cover 24 is displaced, the stopper portion 33 hits the column 21 and the displacement stops, so that the wafer cover 24 does not further displace from the wafer backing pedestal 25.

Third Embodiment A wafer cassette according to the third embodiment has the same structure as that of the first embodiment.
There are four wafer backing pedestals for holding the i-wafer, the supporting columns for holding the Si wafer on the front and back, and the wafer backing pedestals themselves, and the wafer backing pedestals themselves are integrally formed of quartz. Hold two Si wafers. FIG. 12 shows a wafer cassette 68 according to the third embodiment.
It is sectional drawing which looked at from the side. In the figure, reference numerals 36 and 37 denote wafer covers, the wafer cover 36 can cover two Si wafers at the top and bottom, and the wafer cover 37 covers one Si wafer. FIG. 13 is a cross-sectional view taken along a line DD ′ in FIG. 12 and viewed from an oblique upper surface. Note that C- in FIG.
The cross section taken along the line C ′ corresponds to the cross section shown in FIG. The same reference numerals as those described above in the drawings denote the same components.
As shown in FIG. 13, the three pillars 21 of the third embodiment are
Is the same as that of the first embodiment shown in FIG.
Reference numeral 5 is a position shifted leftward from the position in FIG. This is because when the wafer cover 36 is turned in the direction B to remove it from the wafer cassette 68, it can be displaced upward in FIG.

FIG. 14 is a perspective view of the wafer cover 36. As shown in the figure, the inner diameter of the wafer cover 36 has a structure in which two square quartz plates having an opening 27 smaller than the Si wafer by 1 to 5 mm and the four corners of the quartz plate are connected by the connecting portion 34. . The quartz plate has a gap of 3 to 40 mm in order to improve circulation of the solvent therebetween. In the case of liquid phase growth, it is desirable to rotate the wafer cassette 68 in the solvent 64 in the direction B in FIG.

Fourth Embodiment A wafer cassette according to a fourth embodiment is similar to the first embodiment in that
It has four wafer backing pedestals as a holding member for holding the i-wafer, and holds the Si wafer on its front and back. The pillars supporting the wafer backing pedestal and the wafer backing pedestal can be separated. The wafer cassette of the fourth embodiment also has 1,000 wafers.
All are made of quartz so as to withstand temperatures of about ° C.
FIG. 15 is a cross-sectional view of the wafer cassette according to the fourth embodiment as viewed from the side. In the figure, 39 is a wafer backing pedestal, and 40 and 4
Reference numerals 1 and 42 cover the wafer, and 46 is a pin. The same reference numerals as those described above denote the same parts as those described above. In the fourth embodiment, unlike the above-described embodiment, the support 21 and the wafer backing pedestal 39 are not integral but separate. FIG.
6 is a perspective view of a wafer backing pedestal 39, the wafer backing pedestal 39 has a counterbore 31 for holding the Si wafer 6, and
It has four holes 45 through which the columns 21 pass.

FIG. 17A shows a wafer cover 40, FIG.
(B) is a perspective view of the wafer cover 42. Wafer cover 4
Reference numeral 0 denotes two circular quartz plates having openings 27 each having a diameter of 1 to 20 mm smaller than the Si wafer 6 and separated by a gap.
It has a structure connected by two connection parts 38. The gap is 3 to 50 m so that the solvent 64 can easily circulate during liquid phase growth.
m. Outside the opening 27, there is a hole 4 through which the post 21 passes.
There are four of three. The connecting portion 38 is cylindrical and has a hole 43 therethrough. The wafer cover 42 is a single circular quartz plate having an opening 27 having a diameter of 1 to 20 mm smaller than the Si wafer 6, and has four holes 44 passing through the columns 21. FIG.
The wafer cover 41 has the same structure as the wafer cover 24 shown in FIG.

When assembling the wafer cassette according to the fourth embodiment, as shown in the sectional view of FIG.
And the wafer cover 42 is hooked on the protrusion 47 at the lower part of the support 21. Next, one sheet of Si
The column 21 is passed through the hole 45 of the wafer backing base 39 in which the wafer 6 is embedded in the counterbore 31 on each of the front and back sides. Then, the support 21 is passed through the hole 43 of the wafer cover 40 to fix the upper Si wafer 6 on the wafer backing pedestal 39. Next, the support 21 is passed through the hole 45 of the wafer backing pedestal 39 in which one Si wafer 6 is embedded in the counterbore 31 on each of the front and back sides, and the wafer cover 40 is further placed thereon.
Repeat it. Attach the last wafer backing pedestal 39 to support 2
After passing through 1, the wafer backing pedestal 39 and the wafer covers 40 and 42 are fixed by the wafer cover 41 using the groove 28 of the column 21. The wafer cover 41 is fixed in the same manner as in the second embodiment.

A hole 48 is provided at the upper part of the column 21. After the wafer backing pedestal 39 and the wafer covers 40 and 42 are fixed to the column 21, the pin 4 longer than the diameter of the column 21 is inserted into the hole 48.
Insert 6. Next, the support disk 30 is inserted into the support 21. At this time, the pin 46 prevents the support column 30 from falling below the pin 46. Next, the column 21 and the column supporting disk 30 are fixed by assembling the nut 22 to the threaded portion 23 at the top of the column 21.

The wafer cassette 68 assembled as described above is used as a wafer cassette of an immersion type liquid phase growth apparatus similar to the first embodiment described with reference to FIGS. According to the immersion type liquid phase growth apparatus and the growth method of the fourth embodiment, while suppressing the growth of the film on the entire back surface and side surfaces of the Si wafer and the peripheral portion of the front surface of the Si wafer with a small number of parts, Liquid phase growth can be performed only on the desired surface.

[0044]

According to the wafer cassette, the liquid phase growth method and the liquid phase growth apparatus of the present invention, it is possible to prevent unintended film growth on the entire back surface and side surfaces of the wafer and on the periphery of the front surface of the wafer. Then, a film can be grown only on a desired surface. In particular, the present invention can be suitably used for immersion type liquid phase growth which is advantageous for crystal growth of large area wafers. Further, according to the present invention, it is easy to take out and attach the wafer. Also,
When the epitaxial layer is separated from the wafer by using the porous layer, the peripheral portion of the surface where separation is unstable can be excluded from the separation step, which is useful for improving the production yield. For this reason, manufacturing costs of semiconductor devices such as solar cells, epitaxial wafers, and SOI substrates can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view from the side of a wafer cassette according to a first embodiment.

FIG. 2 is a cross-sectional view of the wafer cassette according to the first embodiment as viewed obliquely from above.

FIG. 3 is a cross-sectional view of the wafer cassette according to the first embodiment as viewed obliquely from above.

FIG. 4 is a perspective view of the solar cell of Embodiment 1.

FIG. 5 is a top view of the immersion type liquid phase growth apparatus.

FIG. 6 is a sectional view of an immersion type liquid phase growth apparatus.

FIG. 7 is a diagram illustrating a sequence of an immersion type liquid phase growth apparatus.

FIG. 8 is a cross-sectional view illustrating a manufacturing process of the solar cell.

FIG. 9 is a cross-sectional view illustrating a manufacturing process of the solar cell.

FIG. 10 is a sectional view of an anodizing apparatus.

FIG. 11 is a cross-sectional view of the wafer cassette according to the second embodiment as viewed from an oblique upper surface.

FIG. 12 is a cross-sectional view of a wafer cassette according to a third embodiment as viewed from a side.

FIG. 13 is a cross-sectional view of the wafer cassette according to the third embodiment as viewed from an oblique upper surface.

FIG. 14 is a perspective view of a wafer cover according to the third embodiment.

FIG. 15 is a cross-sectional view of the wafer cassette according to the fourth embodiment as viewed from the side.

FIG. 16 is a perspective view of a wafer backing pedestal according to a fourth embodiment.

FIG. 17 is a perspective view of a wafer cover according to the fourth embodiment.

FIG. 18 is a cross-sectional view illustrating a conventional method of manufacturing a solar cell.

FIG. 19 is a sectional view of a conventional immersion type liquid phase growth apparatus.

[Explanation of symbols]

Reference Signs List 1 front electrode 2 back electrode 3 glass substrate 4 n ⁺ -type Si layer 5 p ^-- type Si layer 6 Si wafer (substrate) 7 porous Si layer 8 non-porous Si layer 11 etching solution 12, 13 metal electrode 14 O-ring 21, 35 Support 22 Nut 23 Threaded portion 24, 36, 37, 40, 41, 42 Wafer cover (cover) 25, 39 Wafer backing pedestal (holding member) 26 Notched portion 27 Opening 28 Groove 29 Ori-flat portion 30 Support column 31 Counterbore (recess) 32, 43, 44, 45, 48 hole 33 Stopper part 34, 38 Connection part 46 Pin 47 Projection part 51 Loading chamber 52 Hydrogen annealing chamber 68 Wafer cassette

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Yoshino 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masaki Mizutani 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Non Co., Ltd. (72) Inventor Akishi Nishida 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (72) Inventor Tetsuro Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Makoto Iwagami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsumi Shoji 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo F-term (reference) 4G077 AA03 BA04 CG02 EG03 QA04 QA54 5F031 CA02 CA05 DA03 EA01 EA07 EA10 EA19 FA03 FA07 FA14 GA19 GA49 HA72 MA04 MA21 MA30 NA07 5F053 AA01 AA32 BB04 BB13 BB52 BB53 BB55 HH04 HH10 LL05 PP03 RR05 RR06 RR13

Claims (12)

[Claims] 1. A wafer cassette for holding a substrate including a holding member having a concave portion corresponding to a shape of a substrate and a cover having an opening smaller than the surface of the substrate, wherein the holding member and the cover include Holding the substrate in the concave portion, and covering one surface and side surfaces of the substrate and all peripheral portions of the other surface with an edge of the concave portion of the holding member and the opening of the cover. Wafer cassette. 2. The wafer cassette according to claim 1, wherein a plurality of the holding members are arranged in parallel, and are supported by columns. 3. A connecting portion of the support column with the holding member has a groove, and the cover is fitted into the groove,
3. The wafer cassette according to claim 2, wherein the cover and the substrate are held. 4. The wafer cassette according to claim 3, wherein the cover is rotated in parallel with the holding member, and the cover is fitted in the groove. 5. The cover is provided with a stopper for preventing rotation of the cover by contacting the support, and the holding is performed so as to fix the cover using the stopper during the growth of a deposited film. The wafer cassette according to claim 4, wherein the member is rotated. 6. The cover according to claim 5, wherein the cover is formed of two plates separated by a space to hold the two substrates, and joins the ends of the two plates via the connection portion. The wafer cassette as described. 7. The wafer cassette according to claim 2, wherein the holding member and the cover have holes through which the columns are passed, and the holding member and the cover are alternately overlapped through the holes. 8. The wafer cassette according to claim 1, wherein a substrate having a porous surface is used as the substrate. 9. A liquid phase growth apparatus for growing a film in a liquid phase on a substrate, wherein the liquid phase growth apparatus transports the wafer cassette according to claim 1. Description: A liquid phase growth apparatus comprising: a system; and a crucible for holding a solvent, wherein the transfer system transfers the wafer cassette to the crucible. 10. The liquid phase growth apparatus according to claim 9, wherein a substrate having a porous surface is used as the substrate held in the wafer cassette. 11. A method for growing a film on a substrate in a liquid phase, wherein the method comprises immersing the wafer cassette according to claim 1 in a solvent while holding the substrate. And the temperature of the solvent is reduced. 12. The liquid phase growth method according to claim 11, wherein a substrate having a porous surface is used as the substrate held in the wafer cassette.