JP4823863B2 - Baking apparatus for manufacturing semiconductor device and semiconductor device manufacturing method - Google Patents

Description

  The present invention relates to a baking apparatus for manufacturing a semiconductor device and a method for manufacturing a semiconductor device, to which a near infrared heater for baking a metal-containing layer is applied.

  Since the solar cell as a semiconductor device uses solar energy, the market is expanding as an environmentally friendly product. With such a situation as a background, improvement in conversion efficiency of solar cells has been attempted. In the case of manufacturing a solar cell using a p-type silicon substrate for the purpose of improving the conversion efficiency of the solar cell, a p + layer (high-level) is formed on the side opposite to the light receiving surface in anticipation of a BSF (Back Surface Field) effect. In general, a p layer having a concentration is formed.

  In order to form the p + layer, the group III element aluminum is laminated on the side opposite to the light-receiving surface by a printing method or a vapor deposition method, and the p + layer is formed by a subsequent heat treatment. Diffusion of aluminum into silicon is often performed by a continuous (belt type, walking beam type, etc.) heating furnace because the manufacturing equipment is inexpensive and the process is simple.

  Since such aluminum diffusion (firing treatment) requires rapid heating, a near-infrared heater having a relatively large watt density is often used as the heater used in the heating furnace. However, when such a near-infrared heater having a large watt density is used, the temperature of the heater body becomes high, and quartz glass as the envelope of the near-infrared heater reacts with aluminum, often causing devitrification. It was.

  FIG. 5 is a plan view schematically showing a conventional baking apparatus for manufacturing a semiconductor device.

  A conventional baking apparatus 101 for manufacturing a semiconductor device includes a near infrared heater 111 and a conveyor belt 122. A plurality of near-infrared heaters 111 are arranged along the conveyance direction SD of the conveyance belt 122 and emit near-infrared IR.

  The transport belt 122 is an infinite conveyor made of a metal mesh belt, and can perform infinite transport in the transport direction SD. At the upper right end of the transport belt 122 in the figure, solar cells 130 on which a metal-containing layer as a firing target is formed are sequentially placed according to the movement of the transport belt 122. Further, the solar cells 130 that have finished firing the metal-containing layer are sequentially discharged to the left end of the transport belt 122 in the drawing.

  In solar cell 130, a metal-containing layer containing metal (aluminum) is formed in advance in the metal-containing layer forming step. In the firing process in the middle of being transported through the firing apparatus 101 for manufacturing a semiconductor device by the transport belt 122, the near-infrared IR emitted from the near-infrared heater 111 is irradiated to the solar cell 130, and the metal-containing layer is fired. A belt drive shaft 122a that rotates the conveyor belt 122 infinitely is disposed at both ends of the baking apparatus 101 (conveyor belt 122) for manufacturing a semiconductor device.

  Generally, the temperature during firing of the metal-containing layer (aluminum) is such that the actual temperature of the solar cell 130 is within a temperature range of 650 ° C. to 850 ° C. in order to diffuse aluminum into the solar cell 130 made of silicon. It is necessary. In order to raise the actual temperature of the solar cell 130 to 650 ° C. to 850 ° C., the actual temperature of the near infrared heater 111 needs to be 1000 ° C. or higher.

  The envelope 112 of the near-infrared heater 111 has good near-infrared IR transmittance and is made of quartz from the viewpoint of durability against high temperatures. In the firing step, aluminum in the metal-containing layer formed on the solar cell 130 may sublimate (in the case of a resin paste containing aluminum, the aluminum scatters together with the resin paste) and may adhere to the outer tube 112. Since aluminum and quartz react at about 800 ° C., there is a problem that the outer tube 112 is devitrified and the life of the near infrared heater 111 is significantly reduced.

  FIG. 6 is an enlarged cross-sectional view schematically showing a cross section in the direction of arrows XX in FIG.

  The baking apparatus 101 for manufacturing a semiconductor device includes an apparatus heat insulating portion 120 that forms the outer wall of the baking furnace. The near-infrared heater 111 is configured to be appropriately held by the apparatus heat insulating portion 120.

For example, Patent Document 1 is known as a document disclosing a conveyor-type firing furnace for forming an electrode of a solar cell element by applying an infrared lamp to form an electrode of the solar cell element and a method for manufacturing the solar cell element.
JP 2002-170972 A

  As described above, in a conventional solar cell (solar cell element) manufacturing method (manufacturing apparatus), when a near-infrared heater having a quartz envelope is used when firing aluminum, aluminum and aluminum are heated at a high temperature. There is a problem that the outer tube is easily devitrified by the reaction of quartz.

  The present invention has been made in view of such a situation, and by providing a quartz protective tube surrounding an outer tube of a near-infrared heater in a baking apparatus for manufacturing a semiconductor device provided with a near-infrared heater, It is an object of the present invention to provide a semiconductor device manufacturing firing device and a semiconductor device manufacturing method with good productivity by preventing devitrification of the outer tube and extending the life of the near infrared heater.

A firing apparatus for manufacturing a semiconductor device according to the present invention includes a near-infrared heater that fires a metal-containing layer formed on a semiconductor substrate and containing a metal, and an apparatus heat insulating portion that constitutes an outer wall and holds the near-infrared heater. A semiconductor device manufacturing firing apparatus comprising a quartz protective tube surrounding a surrounding tube of the near-infrared heater via a spacer , the quartz protective tube being attached to the device heat insulating portion It is characterized by being configured to be held and replaced when devitrified .

With this configuration, it becomes possible to provide a baking apparatus for manufacturing a semiconductor device that can prevent devitrification of the envelope of the near-infrared heater, extend the life of the near-infrared heater, and stably manufacture the semiconductor device. In addition, since a space is provided between the quartz protective tube and the envelope tube via the spacer, it is easy to attach and remove the quartz protective tube, and the workability when replacing the quartz protective tube is good and easy to handle. It becomes possible to make a baking apparatus for manufacturing a semiconductor device.

  In the baking apparatus for manufacturing a semiconductor device according to the present invention, a plurality of the near infrared heaters are arranged, and the quartz protective tube is arranged for each.

  With this configuration, it is possible to reliably protect the near-infrared heater and extend the life of the near-infrared heater (sintering apparatus for manufacturing a semiconductor device).

  In the baking apparatus for manufacturing a semiconductor device according to the present invention, the quartz protective tube is cylindrical.

  With this configuration, it is possible to make an inexpensive quartz protective tube, and it is easy to handle and equalize and can improve heating accuracy, so it is possible to easily and accurately fire a metal-containing layer with high accuracy and good uniformity. It becomes.

  In the baking apparatus for manufacturing a semiconductor device according to the present invention, the metal is aluminum, and the metal-containing layer is heated to 650 ° C. to 850 ° C.

  With this configuration, when aluminum is diffused into the semiconductor substrate, it prevents the devitrification of the outer tube due to aluminum, extends the life of the near infrared heater, and provides a firing device for manufacturing semiconductor devices that operates stably. It becomes possible.

  In the baking apparatus for manufacturing a semiconductor device according to the present invention, the semiconductor device is a solar cell.

  With this configuration, a baking apparatus for manufacturing a semiconductor device (a baking apparatus for manufacturing a solar cell) capable of manufacturing a solar cell with high productivity is obtained.

In addition, a semiconductor device manufacturing method according to the present invention includes a near-infrared heater that bakes a metal-containing layer formed on a semiconductor substrate containing metal, and an apparatus heat insulating portion that constitutes an outer wall and holds the near-infrared heater. Semiconductor device manufacturing using a baking apparatus for manufacturing a semiconductor device, comprising: a transport belt for transporting the semiconductor substrate; and a quartz protective tube surrounding a surrounding tube of the near infrared heater via a spacer. A metal-containing layer forming step of forming the metal-containing layer containing the metal on the semiconductor substrate; and placing the semiconductor substrate on which the metal-containing layer is formed on the transport belt and the near infrared ray And a firing step of firing the metal-containing layer with a heater, wherein the quartz protective tube is held by the device heat insulating portion and is replaced when devitrified .

With this configuration, it becomes possible to provide a semiconductor device manufacturing method capable of preventing the devitrification of the envelope of the near infrared heater, extending the life of the near infrared heater, and stably manufacturing the semiconductor device. Also, quartz protective tubes are easily replaced when devitrified.

  In the semiconductor device manufacturing method according to the present invention, the metal is aluminum, and the metal-containing layer is heated to 650 ° C. to 850 ° C. in the baking step.

  With this configuration, when aluminum is diffused to the semiconductor substrate, the semiconductor device manufacturing can prevent the devitrification of the outer tube by aluminum and extend the life of the near-infrared heater, and manufacture the semiconductor device stably and inexpensively. It becomes possible to be a method.

According to the baking apparatus for manufacturing a semiconductor device and the semiconductor device manufacturing method according to the present invention, since the quartz protective tube surrounding the outer tube of the near infrared heater is provided, devitrification of the outer tube of the near infrared heater is prevented. As a result, the life of the near infrared heater is extended, and the semiconductor device can be stably manufactured. Further, when the quartz protective tube is devitrified, it can be easily replaced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a solar cell manufactured by a baking apparatus for manufacturing a semiconductor device and a semiconductor device manufacturing method according to an embodiment of the present invention. Note that hatching is omitted for the sake of easy viewing.

  A solar cell 30 as a semiconductor device manufactured by the semiconductor device manufacturing firing apparatus and semiconductor device manufacturing method according to the present embodiment includes a semiconductor substrate 31, a surface electrode 32 formed on the surface of the solar cell 30, and a solar cell. A back electrode 33 formed on the back surface of the battery 30. The semiconductor substrate 31 is made of solidified p-type polycrystalline silicon, and an n + layer (high concentration n layer) 34 is formed on the surface electrode 32 side to form a pn junction 31j. In addition, the solar cell 30 in a manufacturing process is supplied as a wafer form and a cell form.

  On the surface of the n + layer 34, a texture portion 35 is formed that includes a large number of projections and depressions for promoting the absorption of sunlight. An antireflection film 36 for preventing the reflection of sunlight is formed on the surface of the texture portion 35. A p + layer (high-concentration p layer) 37 and a back electrode 33 are formed on the back surface of the solar cell 30.

The texture portion 35 is formed by performing dry etching on the solar cell 30 using a chlorine gas such as chlorine trifluoride gas (CClF ₃ ). Alternatively, it is formed by performing wet etching using an alkaline aqueous solution such as a sodium hydroxide aqueous solution (NaOH) or a mixed acid prepared by mixing hydrofluoric acid and nitric acid at a predetermined mixing ratio.

  The antireflection film 36 is made of a silicon nitride film formed by a plasma CVD method using a mixed gas of silane and ammonia as a raw material, or a titanium oxide film formed by a normal pressure CVD method using a titanic acid alkoxide as a raw material.

  The surface electrode 32 is formed by applying a silver (Ag) paste to the light receiving surface of the solar cell 30 and baking it. The p + layer 37 is formed by forming a metal-containing layer containing aluminum (metal) (metal-containing layer forming step) and firing the metal-containing layer at about 700 ° C. (650 ° C. to 850 ° C.). . Formation of a metal content layer can be suitably performed by a vapor deposition method or a printing method. The back electrode 33 is formed by forming the p + layer 37, applying an Ag paste to a part of the back surface (p + layer 37), and baking it.

  As described above, the p + layer 37 is formed in the firing step of firing the metal-containing layer. In the firing step, the near-infrared heater 11 as the firing device for manufacturing a semiconductor device according to the present embodiment (see FIG. 2). ) Apply. Since the metal-containing layer containing aluminum is fired (baking step) at about 700 ° C. (650 ° C. to 850 ° C.), the p + layer 37 can be formed by diffusing aluminum into the semiconductor substrate 31 that is a silicon substrate. It becomes.

  Based on FIG. 2 thru | or 4, the baking apparatus for semiconductor device manufacture which concerns on embodiment of this invention and a semiconductor device manufacturing method are demonstrated.

  FIG. 2 is a plan view schematically showing a baking apparatus for manufacturing a semiconductor device according to an embodiment of the present invention.

  A baking apparatus 1 for manufacturing a semiconductor device according to the present embodiment includes a near-infrared heater 11 and a conveyor belt 22 and is used for manufacturing a semiconductor device. A plurality of near-infrared heaters 11 are arranged along the conveyance direction SD of the conveyance belt 22 and are configured to emit near-infrared IR by, for example, a halogen lamp. In addition, although a belt type baking furnace is illustrated, it is not restricted to a belt type.

  The transport belt 22 is an infinite conveyor made of a metal mesh belt, and can perform infinite transport in the transport direction SD. A solar cell 30 on which a metal-containing layer as a firing target is formed is sequentially placed on the right end of the transport belt 22 in the drawing as the transport belt 22 moves. Further, the solar cells 30 that have finished firing the metal-containing layer are sequentially discharged to the left end of the transport belt 22 in the drawing.

  In the solar cell 30, a metal-containing layer containing metal (aluminum) is formed in advance in the metal-containing layer forming step. In the baking process in the middle of being conveyed through the baking apparatus 1 for manufacturing a semiconductor device by the conveying belt 22, the near-infrared IR emitted from the near-infrared heater 11 is irradiated to the solar cell 30, and the metal-containing layer is baked. A belt drive shaft 22a that rotates the conveyor belt 22 infinitely is disposed at both ends of the baking apparatus 1 (conveyor belt 22) for manufacturing a semiconductor device.

  The near infrared heater 11 has an outer tube 12 that constitutes the outer peripheral shape of the near infrared heater 11. Further, the baking apparatus 1 for manufacturing a semiconductor device includes a quartz protective tube 15 surrounding the outer tube 12 of the near infrared heater 11. Since the quartz protective tube 15 does not block the near-infrared IR from the near-infrared heater 11, the solar cell 30 can be irradiated with the near-infrared IR as in the conventional case. Further, the metal (aluminum) diffused from the metal-containing layer in the firing step adheres to the quartz protective tube 15 and does not adhere to the outer tube 12.

  Therefore, the firing device 1 for manufacturing a semiconductor device can prevent devitrification of the outer tube 12 of the near-infrared heater 11 to extend the life of the near-infrared heater 11 and stably manufacture the semiconductor device (solar cell 30). Is possible. That is, the expensive near-infrared heater 11 does not need to be replaced, and when the quartz protective tube 15 which is cheaper than the near-infrared heater 11 is devitrified, the replacement is further continued by replacing the quartz protective tube 15. Can be used.

  Note that power supply lines 14 for supplying power to the near infrared heater 11 are connected to both ends of the outer tube 12 via power supply terminals 13.

  A plurality of near infrared heaters 11 are arranged, and a quartz protective tube 15 is arranged for each. Therefore, the workability at the time of replacement | exchange with respect to the failure | damage etc. of the quartz protective tube 15 can be improved, and the near-infrared heater 11 is protected reliably and the lifetime of the baking apparatus 1 for semiconductor device manufacture (near-infrared heater 11) is extended. It becomes possible.

  FIG. 3 is an enlarged cross-sectional view schematically showing a cross section in the direction of arrows XX in FIG. In the figure, the thickness of the quartz protective tube 15 is ignored.

  The baking apparatus 1 for manufacturing a semiconductor device includes an apparatus heat insulating portion 20 that forms the outer wall of the baking furnace. The near-infrared heater 11 and the quartz protective tube 15 are configured to be appropriately held by the apparatus heat insulating portion 20. That is, the quartz protective tube 15 is configured to surround the outer tube 12 via an appropriate spacer 21.

  Since a space is provided between the quartz protective tube 15 and the envelope tube 12, the quartz protective tube 15 can be easily attached and detached, and the workability when exchanging the quartz protective tube 15 is good. It becomes possible to make the baking apparatus 1 for manufacturing a semiconductor device easy.

  FIG. 4 is a perspective view schematically showing the quartz protective tube shown in FIGS.

  Since the quartz member is inexpensive in terms of the cylindrical shape, the quartz protective tube 15 has a cylindrical shape. Further, by using a cylindrical shape, it is possible to irradiate the solar cell 30 with the near infrared IR from the outer tube 12 evenly. Therefore, the quartz protective tube 15 can be constructed at low cost, and can be easily handled and soaked, and the heating accuracy can be improved. Therefore, the metal-containing layer can be easily and accurately fired with high accuracy and uniformity. .

  As described above, in the semiconductor device manufacturing firing apparatus 1 and the semiconductor device manufacturing method according to the present embodiment, the metal contained in the metal-containing layer is aluminum, and the metal-containing layer is heated to 650 ° C. to 850 ° C. As a configuration. Accordingly, aluminum can be diffused into the semiconductor substrate 31 in the firing step, and the p + layer 37 can be easily and stably formed on the semiconductor substrate 31 of the solar cell 30. In addition, it is possible to prevent the devitrification of the outer tube 12 due to the diffusion of aluminum in the baking process, thereby extending the life of the near-infrared heater 11 and to make the baking apparatus 1 for manufacturing a semiconductor device operating stably.

  In the semiconductor device manufacturing firing apparatus 1 and semiconductor device manufacturing method according to the present embodiment, it is possible to manufacture the solar cell 30 as a semiconductor device with high productivity. This is particularly effective when a high-concentration p layer (p + layer 37) corresponding to the back electrode 33 of the semiconductor substrate 31 of the solar cell 30 is formed of aluminum. That is, the baking apparatus 1 for manufacturing a semiconductor device is a baking apparatus for manufacturing a solar cell, and the semiconductor device manufacturing method is a solar cell manufacturing method.

It is sectional drawing which shows schematic structure of the solar cell manufactured by the baking apparatus for semiconductor device manufacture which concerns on embodiment of this invention, and a semiconductor device manufacturing method. It is a top view which shows the outline of the baking apparatus for semiconductor device manufacture which concerns on embodiment of this invention. It is sectional drawing which expands and shows the outline of the cross section in the arrow XX direction of FIG. It is a perspective view which shows the outline of the quartz protective tube shown in FIG. 2 and FIG. It is a top view which shows the outline of the baking apparatus for conventional semiconductor device manufacture. It is sectional drawing which expands and shows the outline of the cross section in the arrow XX direction of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device manufacturing baking apparatus 11 Near-infrared heater 12 Outer tube 13 Power supply terminal 14 Power supply line 15 Quartz protective tube 20 Apparatus heat insulation part 21 Spacer 22 Conveyance belt 30 Solar cell 31 Semiconductor substrate 32 Front surface electrode 33 Back surface electrode 34 n + layer 35 texture portion 36 antireflection film 37 p + layer

Claims (7)

A semiconductor device manufacturing baking comprising: a near- infrared heater for firing a metal-containing layer formed on a semiconductor substrate containing a metal; and a device heat insulating portion that constitutes an outer wall and holds the near-infrared heater. A device,
A quartz protective tube that surrounds the envelope of the near-infrared heater through a spacer ,
A firing apparatus for manufacturing a semiconductor device, wherein the quartz protective tube is held by the device heat insulating portion and is replaced when devitrified .   2. The baking apparatus for manufacturing a semiconductor device according to claim 1, wherein a plurality of the near infrared heaters are disposed, and the quartz protective tube is disposed for each of the near infrared heaters. The quartz protective tube, for manufacturing a semiconductor device baking apparatus according to claim 1 or claim 2 characterized in that it is a cylindrical shape. Said metal is aluminum, the metal-containing layer for manufacturing a semiconductor device baking apparatus according to any one of claims 1 to claim 3, characterized in that it is constituted to be heated to no 650 ° C. to 850 ° C. . The said semiconductor device is a solar cell, The baking apparatus for semiconductor device manufacture as described in any one of Claim 1 thru | or 4 characterized by the above-mentioned. A near-infrared heater that bakes a metal-containing layer formed on a semiconductor substrate containing metal, an apparatus heat insulating portion that constitutes an outer wall and holds the near-infrared heater, a transport belt that transports the semiconductor substrate, and a spacer A semiconductor device manufacturing method using a baking apparatus for manufacturing a semiconductor device, comprising a protective tube made of quartz surrounding an outer tube of the near infrared heater through the semiconductor device,
A metal-containing layer forming step of forming the metal-containing layer containing the metal on the semiconductor substrate;
A firing step of placing the semiconductor substrate on which the metal-containing layer is formed on the transport belt and firing the metal-containing layer with the near-infrared heater;
The method of manufacturing a semiconductor device, wherein the quartz protective tube is held by the device heat insulating portion and is replaced when devitrified . The method of manufacturing a semiconductor device according to claim 6 , wherein the metal is aluminum, and the metal-containing layer is heated to 650 ° C. to 850 ° C. in the baking step.

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