JP2012119453A - Impurity diffusion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an impurity diffusion apparatus capable of performing a uniform impurity diffusion on semiconductor element substrates over the whole region in a quartz tube.SOLUTION: The impurity diffusion apparatus includes a quartz tube heated by a heater disposed at an outer peripheral part thereof; a plurality of cage-shaped child boards with which a plurality of semiconductor element substrates, whose surfaces are set parallel to a central axis of the quartz tube, are aligned and vertically arranged at equal spatial intervals in a direction orthogonal to the central axis, and dummy substrates are vertically arranged at equal spatial intervals on the outermost side closer to the substrate surfaces of the plurality of semiconductor element substrates; a parent board with which the plurality of child boards are aligned and mounted in a row at predetermined spatial intervals in the central axis direction, and are transferred into the quartz tube; a diffusion gas generator for generating diffusion gas for diffusing impurity into the semiconductor element substrates; and a diffusion gas inlet tube which is connected to the diffusion gas generator and is extended into the quartz tube, and has openings respectively disposed at axial positions of the plurality of child boards aligned and arranged in the row in the central axis direction.

Description

  The present invention relates to an impurity diffusion device used for manufacturing a semiconductor element including a solar cell.

  Conventionally, a quartz tube heated by a heater provided on the outer periphery and a liquid diffusion source are bubbled by a source gas, and a source gas containing saturated vapor of the liquid diffusion source is merged with a carrier gas to form a diffusion gas stream. An apparatus for introducing a gas gas flow into the quartz tube from one end thereof, and a semiconductor element substrate with the substrate surface in a fixed orientation and parallel to the central axis of the quartz tube. And a plurality of channel plates formed with the same outer diameter as the semiconductor element substrate can be arranged on the substrate surface side of the semiconductor element substrate in the semiconductor element substrate row group. A half boat provided on the outermost side with a sub boat arranged at the same dimension as the interval, and a main boat that allows a plurality of sub boats to be arranged in the same direction as the central axis. Impurity diffusion apparatus is disclosed in the body production process (for example, see Patent Document 1).

  In the above impurity diffusing apparatus, after a quartz child boat in which a plurality of semiconductor element substrates such as silicon substrates (particularly, solar cell substrates) are arranged and arranged vertically is transferred to a quartz tube (horizontal furnace) heated by a heater. Then, a diffusion gas (a gas containing impurities) is introduced into the horizontal furnace, and the impurities are thermally diffused into the semiconductor element substrate to form a pn junction.

  When performing impurity thermal diffusion, a plurality of semiconductor element substrates placed vertically in the sub-boat are arranged at regular intervals, and the gas flow rate between the substrates is almost the same. On the outer substrate surface side, there is an interval corresponding to the distance between the horizontal furnace and the substrate, the gas flow rate is different compared to other substrates, the impurity diffusion conditions are different, the diffusion concentration and sheet resistance vary, The characteristics of semiconductor elements vary. Therefore, flow path plates (dummy substrates) formed with the same outer diameter as the semiconductor element substrate are arranged at equal intervals on the outermost surface of the semiconductor element substrate on the substrate surface side.

JP 2001-185502 A

  However, according to the above conventional technique, there is a problem that the gas distribution becomes non-uniform between the diffusion gas introduction side and the exhaust side of the quartz tube. Specifically, near the introduction side, the introduced gas contacts the child boat or the semiconductor element substrate and diffuses rapidly. Immediately after the rapidly diffusing gas, a region with a low impurity concentration is generated, which is not uniform. In addition, in the child boat near the exhaust side, in addition to the gas flowing from the introduction side to the exhaust side, there is also gas that is blocked and retained by the door on the exhaust side, so compared with other child boats Gas will be supplied excessively. In recent years, with the increase in production of solar cells worldwide, the length of the quartz tube (horizontal furnace) tends to become longer and the unevenness of gas distribution on the introduction side and the exhaust side tends to become even larger. In addition, the gas distribution is uneven in the sub boat.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an impurity diffusion device capable of performing uniform impurity diffusion in a semiconductor element substrate over the entire area in a quartz tube (horizontal furnace). .

  In order to solve the above-described problems and achieve the object, the present invention provides a quartz tube heated by a heater disposed on the outer peripheral portion, a plurality of semiconductor element substrates, and a plate surface of the quartz tube as a central axis. The dummy substrate is vertically placed at equal intervals on the outermost side of the substrate surface side of the plurality of aligned semiconductor element substrates, in parallel with each other and in a direction perpendicular to the central axis. A plurality of saddle-shaped child boats, a plurality of child boats arranged in a line at predetermined intervals in the central axis direction, and placed in a row and transferred into the quartz tube, and the semiconductor element substrate A diffusion gas generator for generating a diffusion gas for diffusing impurities, and a plurality of children connected to the diffusion gas generator and extending into the quartz tube and arranged in a line in the central axis direction Each of the boats A diffusion gas inlet pipe having an opening in the direction position, further comprising the features.

  According to the present invention, a uniform diffusion gas is blown to each child boat, and impurity diffusion is performed on each semiconductor element substrate by the uniform diffusion gas, and the diffusion gas introduction side and the exhaust of the quartz tube are exhausted. There is an effect that the non-uniform distribution of the diffusion gas generated between the two sides is eliminated.

FIG. 1 is a diagram showing Embodiment 1 of an impurity diffusion device according to the present invention. FIG. 2 is a diagram showing a second embodiment of the impurity diffusion device according to the present invention. FIG. 3-1 is a diagram of a third embodiment of an impurity diffusion device according to the present invention. 3-2 is a side view illustrating a gas blowing nozzle of the impurity diffusion device according to Embodiment 3. FIG. FIG. 3-3 is a top view illustrating a gas blowing nozzle of the impurity diffusion device according to the third embodiment. FIG. 4A is a diagram of a fourth embodiment of an impurity diffusion device according to the present invention. FIG. 4-2 is a side view illustrating a gas blowing nozzle of the impurity diffusion device according to the fourth embodiment. FIG. 3-3 is a top view illustrating a gas blowing nozzle of the impurity diffusion device according to the fourth embodiment. FIG. 5-1 is a diagram showing Embodiment 5 of an impurity diffusion device according to the present invention. FIG. 5-2 is a perspective view illustrating a gas blowing nozzle of the impurity diffusion device according to the fifth embodiment.

  Embodiments of an impurity diffusion apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing Embodiment 1 of an impurity diffusion device according to the present invention. The quartz tube 1 of the impurity diffusion device 91 according to the first embodiment is formed in a cylindrical shape. A cylindrical heater 11 for uniformly heating the quartz tube 1 is disposed on the outer periphery of the quartz tube 1. The quartz tube 1 and the heater 11 constitute a horizontal furnace.

  One end (right side) of the quartz tube 1 serves as an entrance / exit of a parent boat 21 described later. The entrance and exit are provided with a quartz door 5 for closing the entrance and an exhaust hood (not shown) for collecting purge gas (residual gas in the quartz tube 1) when the quartz door 5 is opened. Yes. The other end (left side) of the quartz tube 1 is closed, and a diffusion gas introduction tube 15 described later is inserted therethrough.

  The diffusion gas generator 19 includes a container 16 for storing the liquid diffusion source 17, a carrier gas introduction pipe 13 for supplying the carrier gas into the quartz tube 1, and a source gas for bubbling the liquid diffusion source 17 in the container. And a source gas introduction pipe 14 to be supplied. The diffusion gas generator 19 causes the saturated vapor of the liquid diffusion source 17 to be included in the source gas by bubbling, and this source gas is merged with the carrier gas to form a diffusion gas, which is diffused via the diffusion gas introduction pipe 15. A working gas is introduced into the quartz tube 1.

  As the liquid diffusion source 17, phosphorus oxychloride is used, but phosphorus tribromide or boron tribromide may be used. The carrier gas is a mixture of nitrogen gas and a small amount of oxygen gas, and the source gas is nitrogen gas.

  In the boat 2, four quartz rod-like child boats 22 are arranged in a row at predetermined intervals in the central axis direction of the quartz tube 1 on a parent boat 21 that forms a substantially rectangular tray. It is what I put. The child boat 22 is formed by combining quartz rods and welding them to form a substantially rectangular parallelepiped bowl shape (frame shape). The parent boat 21 is also formed by combining quartz rods and welding them to form a substantially rectangular ladder. Therefore, the diffusion gas can freely flow in the child boat 22.

  A plurality of (three) semiconductor element substrates (silicon substrates) 3 are vertically arranged in the child boat 22 with their plate surfaces parallel to the central axis of the quartz tube 1 and at equal intervals in a direction perpendicular to the central axis. The flow path plate (dummy substrate) 4 having the same shape as that of the semiconductor element substrate 3 is placed on the outermost surface of the plurality of aligned semiconductor element substrates 3 on the substrate surface side, and the distance between the semiconductor element substrates 3 is the same. Place vertically at intervals.

  The child boat 22 on which the silicon substrate 3 and the flow path substrate 4 are placed is placed on the parent boat 21 and transferred into the horizontal furnace 10 composed of the quartz tube 1 and the heater 11.

  In the quartz tube 1, a diffusion gas introduction pipe 15 connected to a diffusion gas generator 19 is extended and disposed below the parent boat 21 over substantially the entire length of the quartz tube 1. Openings 18 are provided upward in the diffusion gas introduction pipe 15 at predetermined intervals. Each opening 18 is formed in the diffusion gas introduction pipe 15 so that the main boat 21 on which the sub boat 22 is placed is transported to a fixed position in the horizontal furnace 10 so as to be positioned directly below each sub boat 22. Has been placed.

  According to the impurity diffusing apparatus of the first embodiment described above, a uniform diffusion gas is blown out directly below each sub-boat 22, and the impurity diffusion is performed on the semiconductor element substrate 3 by the uniform diffusion gas. The uneven distribution of the diffusion gas that has occurred between the introduction side and the exhaust side of the tube 1 can be reduced.

Embodiment 2. FIG.
FIG. 2 is a diagram showing a second embodiment of the impurity diffusion device according to the present invention. The impurity diffusing device 92 of the second embodiment is different from the impurity diffusing device 91 of the first embodiment in that a diffusion gas introducing tube 15 connected to the diffusion gas generating device 19 and extended into the quartz tube 1 is provided. In other words, the quartz tube 1 is disposed on the upper side of the child boat 22 over substantially the entire length. The diffusion gas introduction pipe 15 is provided with openings 18 at regular intervals, and each opening 18 is provided when the main boat 21 on which the child boat 22 is placed is transferred to a fixed position in the horizontal furnace 10. In addition, the diffusion gas introduction pipe 15 is disposed in a downward direction so as to be located immediately above each of the child boats 22. Portions other than the configuration of the diffusion gas introduction pipe 15 described above are not different from the impurity diffusion device 91 of the first embodiment.

  According to the impurity diffusing device 92 of the second embodiment, a uniform diffusion gas is blown out from directly above each child boat 22, and the impurity diffusion is performed on the silicon substrate 3 by the uniform diffusion gas. The non-uniform distribution of the diffusion gas generated between the introduction side and the exhaust side can be reduced.

Embodiment 3 FIG.
FIG. 3-1 is a diagram illustrating a third embodiment of the impurity diffusion device according to the present invention, and FIG. 3-2 is a side view illustrating a gas blowing nozzle of the impurity diffusion device according to the third embodiment. 3-3 is a top view showing a gas blowing nozzle of the impurity diffusion device of the third embodiment.

  The impurity diffusing device 93 of the third embodiment is different from the impurity diffusing device 91 of the first embodiment, as shown in FIGS. 3-1 to 3-3, in the diffusion gas introduction pipe 15 at a predetermined interval. That is, a quartz T-shaped gas blowing nozzle 33 is mounted in the opening 18 provided. The horizontal pipe 33a of the gas blowing nozzle 33 is provided with a plurality (five) of gas blowing ports 33b, and the diffusion gas introduced into the vertical pipe 33c attached to the opening 18 is supplied to the horizontal pipe 33a. It branches in a connection part and blows off from the some gas blowing outlet 33b. By using the gas blowing nozzle 33, it is possible to supply the diffusion gas in a wider range and more uniformly than when the gas is blown from the opening 18. The gas blowing nozzle 33 may be attached to the opening 18 of the diffusion gas introduction pipe 15 of the impurity diffusion device 92 of the second embodiment.

Embodiment 4 FIG.
FIG. 4-1 is a diagram illustrating an impurity diffusion device according to a fourth embodiment of the present invention, and FIG. 4-2 is a side view illustrating a gas blowing nozzle of the impurity diffusion device according to the fourth embodiment. 4-3 is a top view showing a gas blowing nozzle of the impurity diffusion device according to the fourth embodiment.

  The impurity diffusing device 94 of the fourth embodiment is different from the impurity diffusing device 93 of the third embodiment in that, as shown in FIGS. The gas outlet nozzle 34 different from the gas outlet nozzle 33 of the third embodiment is rotatably mounted in the provided opening 18. The horizontal pipe 34a of the gas outlet nozzle 34 is provided with a plurality (five) of gas outlets 34b. The gas outlet 34b is arranged at one end (left side) of the horizontal pipe 34a as shown in FIG. It is provided on the front side (lateral direction) of the paper, and on the other side (right side), it is provided on the back side (the side opposite to the horizontal direction). The diffusion gas introduced into the vertical pipe 34c from the opening 18 branches at the connection portion of the horizontal pipe 34a, blows out from the left and right gas blowout ports 34b, and is blown out by the reaction force generated when the diffusion gas blows out. The nozzle 34 rotates around the vertical pipe 34 c, and the diffusion gas can be supplied from a position just below each child boat 22 in a wide range and uniformly.

  The impurity diffusing device 94 according to the fourth embodiment can supply the same amount of diffusion gas from directly below each of the child boats 22 mounted on the parent boat 21, and the impurity diffusing device 93 according to the third embodiment. Compared to the above, the diffusion gas can be uniformly supplied into each child boat 22, and the non-uniform distribution of the diffusion gas between the child boats 22 and in the child boat 22 can be reduced. That is, the semiconductor element substrate 3 having a high yield can be manufactured by performing more uniform impurity diffusion throughout the impurity diffusion device 94 to suppress the characteristic variation of the semiconductor element substrate 3. The gas blowing nozzle 34 may be attached to the opening 18 of the diffusion gas introduction pipe 15 of the impurity diffusion device 92 of the second embodiment.

Embodiment 5 FIG.
FIG. 5-1 is a diagram showing a fifth embodiment of the impurity diffusion device according to the present invention, and FIG. 5-2 is a perspective view showing a gas blowing nozzle of the impurity diffusion device according to the fifth embodiment. As shown in FIGS. 5A and 5B, in the impurity diffusion device 95 of the fifth embodiment, the diffusion gas introduction pipe 15 corresponds to each of the child boats 22 carried into the quartz tube 1. In each of the branch pipes (divided gas introduction pipes for diffusion) 151 to 154, one opening 18 is provided at each tip.

  The branch pipes 151 to 154 are each provided with a flow rate adjusting device 40, and the flow rate can be adjusted individually for each branch pipe 151 to 154. Further, the opening 18 is provided with a water outlet-like gas outlet nozzle 35 provided with a large number of gas outlets 35b. The diameter of the gas blowing nozzle 35 is approximately the same as the length of one side of the child boat 22.

  By installing the gas blowing nozzle 35, the diffusion gas can be supplied to a wider range. Further, since the branch pipes 151 to 154 including the flow rate adjusting device 40 are arranged for each child boat 22, the non-uniform distribution of the diffusion gas between the child boats 22 can be further reduced.

  In addition, you may arrange | position each branch pipe 151-154 on the upper side of the child boat 22. FIG. Further, the gas blowing nozzle 35 may be attached to the opening 18 of the diffusion gas introduction pipe 15 of the impurity diffusion device 91 of the first embodiment or the impurity diffusion device 92 of the second embodiment. Further, the gas blowing nozzle 33 of the third embodiment or the gas blowing nozzle 34 of the fourth embodiment may be attached to the opening 18 of each branch pipe 151 to 154 of the impurity diffusion device 95 of the fifth embodiment.

  As described above, the impurity diffusion device according to the present invention is useful for manufacturing a semiconductor element including a solar cell.

1 quartz tube 2 boat 21 parent boat 22 child boat 3 silicon substrate (semiconductor element substrate)
4 Dummy substrate (channel plate)
5 Quartz door 10 Horizontal furnace 11 Heater 13 Carrier gas introduction pipe 14 Source gas introduction pipe 15 Diffusion gas introduction pipe 151-154 Branch pipe (diffusion gas introduction pipe)
16 Container 17 Liquid Diffusion Source 18 Opening 19 Diffusion Gas Generator 33, 34, 35 Gas Outlet Nozzle 33a, 34a Horizontal Pipe 33b, 34b, 35b Gas Outlet 33c, 34c Vertical Pipe 40 Flow Control Equipment 91-95 Impurity Diffusion apparatus

Claims (8)

A quartz tube heated by a heater disposed on the outer periphery,
A plurality of semiconductor element substrates are placed vertically with their plate surfaces parallel to the central axis of the quartz tube and aligned at equal intervals in a direction perpendicular to the central axis, and a plurality of dummy substrates are aligned. A plurality of bowl-shaped child boats arranged vertically at equal intervals on the outermost surface of the substrate surface side of the semiconductor element substrate,
A plurality of child boats arranged in a row at a predetermined interval in the central axis direction, and placed into a row, and transferred to the quartz tube;
A diffusion gas generator for generating a diffusion gas for diffusing impurities in the semiconductor element substrate;
A diffusion gas introduction pipe connected to the diffusion gas generator and extending into the quartz tube and having an opening at each axial position of a plurality of sub-boats arranged in a line in the central axis direction When,
An impurity diffusion apparatus comprising:   The impurity diffusion apparatus according to claim 1, wherein the diffusion gas introduction pipe is branched corresponding to each of the plurality of sub-boats.   The impurity diffusion apparatus according to claim 2, wherein a flow rate adjusting device is attached to each of the branched diffusion gas introduction pipes.   The impurity diffusion device according to claim 1, wherein the diffusion gas introduction pipe is disposed below the parent boat, and the opening is provided upward. .   The impurity diffusion apparatus according to claim 1, wherein the diffusion gas introduction pipe is disposed on an upper side of the child boat, and the opening is provided downward.   6. A vertical tube of a T-shaped gas blowing nozzle is attached to the opening, and a plurality of gas blowing ports are provided in a horizontal tube of the gas blowing nozzle. The impurity diffusion device according to any one of the above.   The vertical pipe is rotatably attached to the opening, and a gas outlet is provided on one end of the horizontal pipe in a lateral direction, and a gas outlet is provided on the other end in a direction opposite to the lateral direction. The impurity diffusion device according to claim 6, wherein the gas blowing nozzle is rotated around the vertical pipe by a gas blowing reaction force.   6. The impurity diffusing apparatus according to claim 1, wherein a water outlet-like gas outlet nozzle having a large number of gas outlets is attached to the opening.

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