JP2009238991A - Heat treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment apparatus that prevents a material to be heated from sliding down during conveyance while preventing it from cracking during a heat treatment by using a conveyance system using a walking beam. <P>SOLUTION: The heat treatment apparatus heat-treats the material to be heated by: conveying the material to be heated which is conveyed by the walking beam driven by a conveyance device into a heat-treatment furnace having a heater; and passing it through the heat-treatment furnace, wherein at least the walking beam has a support portion for supporting one material to be heated at four or more points when the material to be heated is mounted, and a slide-down preventing means for the material to be heated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus using a walking beam conveyance system, among other heat treatment apparatuses.

  A continuous furnace is used for diffusion of single crystal or polycrystalline solar cells and firing during electrode formation. By using this continuous furnace, many semiconductor substrates can be heat-treated continuously, and the productivity is extremely high.

There is a belt type continuous furnace as such a continuous furnace. In this belt-type continuous furnace, an object to be heated is placed on a conveyor belt that passes through the heating section of the baking furnace, and the conveyor belt is rotated endlessly, thereby passing through the heating section of the heat treatment furnace. , Firing.
However, because of concerns about belt contamination, a walking beam using quartz or ceramic rods may be used as a transport system for a continuous furnace.

  FIG. 3 is a diagram showing a general form of a conventional walking beam, and FIG. 4 is a side view of a state in which an object to be heated W is placed on the conventional walking beam. The normal walking beam includes a fixed beam 31 fixed to the furnace and a movable beam 32 that is driven with a predetermined stroke and conveys the article to be heated W.

  In this walking beam, first, the movable beam 32 rises, and the object to be heated W placed on the fixed beam 31 is received from the fixed beam 31, and the object to be heated W is placed on the movable beam 32 as shown in FIG. Is further raised, and stops at the rising edge. Next, the movable beam 32 moves forward by one stroke while holding the article to be heated W and stops. Next, the movable beam 32 descends, delivers the semiconductor substrate to the fixed beam 31, further descends, then retracts by one stroke, stops, and returns to the original position.

At this time, some support pins are provided on the walking beam to support the object to be heated (see, for example, Patent Document 1).
By the method as described above, the object to be heated passes through the heating part of the heat treatment furnace by the walking beam and is fired.
However, in recent years, since the semiconductor substrate has become thinner and its strength has decreased, there has been a problem that the semiconductor substrate is broken while the semiconductor substrate is being transported by the walking beam.

Japanese Patent Laid-Open No. 2003-176011

  Therefore, the present invention has been made to solve the above-described problems, and can use a walking beam conveyance system to prevent the object to be heated during heat treatment from occurring and to prevent slipping during conveyance. It is to provide a heat treatment apparatus.

  In order to solve the above-mentioned problem, the present invention is such that at least a heated object conveyed by a walking beam driven by a conveying device is conveyed into a heat treatment furnace having a heater and passes through the heat treatment furnace, thereby In a heat treatment apparatus for performing heat treatment on an object to be heated, at least the walking beam has a support part for supporting at least four points when placing the one object to be heated, and the object to be heated There is provided a heat treatment apparatus characterized by having a slip prevention means.

In this way, with the walking beam of the present invention, the object to be heated is supported by points during the heat treatment, so that the contact portion between the object to be heated and the walking beam can be made small. Thereby, the temperature difference generated in the vicinity of the contact portion of the heated object due to the walking beam and the heated object coming into contact can be greatly reduced, and cracking of the heated object due to the temperature difference is effectively prevented. be able to. Furthermore, if supported at four or more points, relatively stable conveyance is possible.
In addition, since the walking beam and the object to be heated contact only at points during the heat treatment, it is possible to minimize the heating unevenness of the object to be heated and the interference with the application part of the electrode material when manufacturing the solar cell element. it can.

  Furthermore, since the walking beam of the present invention has a function of preventing slipping, it is possible to prevent cracks due to slipping during transport of an object to be heated that has become unstable due to a reduction in the contact portion when placing the object to be heated. Can do.

Further, the slip-preventing means can be stoppers respectively provided on the walking beam at the rear of the support portion of the object to be heated.
In this way, if the slip prevention means is a stopper, it can be easily installed on the walking beam, and the heated object that is being transported often slides backward. Can prevent sliding down.

Furthermore, the support unit includes at least two support units for placing the one object to be heated on both sides in the transport direction, thereby supporting one object to be heated with a total of four or more points. (Claim 3).
In this way, by supporting the object to be heated at two points on both sides, it is possible to more stably and efficiently disperse the load concentration on the contact portion of the object to be heated to be supported.

It is preferable that the support part and / or the slip-off preventing means is a cylindrical rod-like body.
In this way, by supporting the object to be heated by using the walking beam support portion of the present invention as a cylindrical rod-like body, there is no contact at the center portion, so that the contact area can be further reduced. Furthermore, since the load stress concentration when supporting the object to be heated can be effectively relaxed, it is possible to prevent cracking due to the load of the object to be heated itself. Moreover, installation is easy and it is advantageous also in terms of cost.
Furthermore, the same thing as a support part can also be utilized also about a sliding-off prevention means.

It is preferable that the material of the support part and / or the slip-preventing means is ceramic.
Thus, if the material of the support part and / or slip-off prevention means is ceramic, when using a walking beam having a high heat resistance and a material having a lower coefficient of thermal expansion than ceramic, a hole is provided in the walking beam, The support portion and / or the slip-off preventing means can be provided by a simple method such as inserting a pin there. In other words, if the pin is inserted in a cold state, the pin is firmly fixed by the thermal expansion of the ceramic during heating, and the support part and / or the slip-preventing means are not removed.

The said heat processing apparatus can be utilized when baking the semiconductor substrate which apply | coated the electrode material in manufacture of a solar cell element (Claim 6).
With the heat treatment apparatus of the present invention, since the semiconductor substrate is supported by dots, there is almost no interference with the portion where the electrode material is applied, and heating unevenness can be prevented. Furthermore, since the semiconductor substrate can be fired with few cracks, the defect rate and crystal cost during firing of the semiconductor substrate for solar cells can be reduced.

  The heat treatment apparatus of the present invention can reduce the cracking of the object to be heated during the heat treatment compared to the conventional heat treatment apparatus using a walking beam, and can effectively prevent sliding during the conveyance of the object to be heated. can do. Thereby, it is possible to reduce the defect rate and the crystal cost during firing of the semiconductor substrate, particularly in the manufacture of solar cell elements.

  When performing heat treatment using a normal walking beam transfer system, the object to be heated is placed on the walking beam in the state shown in FIG. Although heat treatment was performed on the object, there was a problem that the object to be heated was cracked.

The present inventors have studied to solve such a problem.
As a cracking method when the heated object is cracked, it is not a cracking method that is usually cracked by a crystal orientation such as a silicon substrate as shown in FIG. 2A, but in contact with a walking beam as shown in FIG. There were many cracks along the part.

In the conventional walking beam, as shown in FIG. 4, since the entire upper surface of the walking beam is in contact with the object to be heated, it can be estimated that an extreme temperature difference occurs in the vicinity of the contact portion of the object to be heated.
From these, the present inventors have found that the cause of the object to be heated cracking is the damage caused by the temperature difference.

  For this reason, if a support pin etc. are provided on a walking beam and a to-be-heated material is supported by a point by it, the contact part of a walking beam and a to-be-heated material can be made small. As a result, it has been found that an extreme temperature difference does not occur in the vicinity of the contact portion of the object to be heated with the walking beam, and cracks derived from the temperature difference can be prevented.

However, as the contact portion between the object to be heated and the walking beam is made smaller, the object to be heated becomes more unstable during transportation and may slide off the walking beam.
For this, the present inventors provide a walking beam with anti-sliding means, and by preventing the object to be heated from sliding down, by performing good heat treatment that prevents cracking of the object to be heated by supporting it at a point, The present invention was completed by conceiving that the object to be heated can be stably conveyed.

  Embodiments of a heat treatment apparatus according to the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to these forms.

  FIG. 1 is a side view of a state in which an object to be heated is placed on a walking beam in the embodiment of the present invention. FIG. 5 is a view showing an example of a heat treatment apparatus using the walking beam conveyance system in the embodiment of the present invention. FIG. 6 is an explanatory view when the object to be heated is conveyed by the walking beam in the embodiment of the present invention, and FIG. 6A shows a state in which the object to be heated is placed on the fixed beam. (B) is the figure which is conveyed in the state by which the to-be-heated material was mounted on the movable beam.

  In FIG. 5, in the heat treatment apparatus 55, the article to be heated W placed on the walking beam 52 driven by the conveyance apparatus 51 is conveyed into a plurality of heat treatment furnaces having heaters 53a, 53b, 53c, and the heat treatment furnace 54a. , 54b and 54c are passed through the multi-stage heat treatment of the article W to be heated.

  In FIG. 5, the section in which the article to be heated W can be heated by three heat treatment furnaces is three sections, but it may be more or less. For example, if it is a heat treatment furnace used for firing solar cells, a low temperature section for burning organic components in the conductive paste of the electrode material and a high temperature section for sintering the metal powder behind it are required. Become. Further, the number of heaters and the structure of the heat treatment furnace are not particularly limited, and may be appropriately changed depending on the heat treatment conditions and the like according to the purpose.

  In the present invention, the basic operation of the walking beam 52 is the same as that of the conventional walking beam. That is, as shown in FIG. 6A, the object to be heated W is held by the support portion 12 on the fixed beam 61, and the operation starts from a state where the movable beam 11 is positioned below the fixed beam 61. First, the movable beam 11 gradually rises, receives the object to be heated W placed on the fixed beam 61 from the fixed beam 61, and the object to be heated W is placed on the movable beam 11 in the state shown in FIG. It is placed on the support unit 12. From there, the movable beam 11 rises until it is positioned above the fixed beam 61, resulting in a state as shown in FIG.

Next, the movable beam 11 descends, delivers the object to be heated W to the fixed beam 61, further descends, and then moves backward by one stroke to return to the initial positional relationship shown in FIG.
By repeating such a cycle, the object to be heated W is sequentially and intermittently conveyed in the heat treatment furnace to perform heat treatment.
Ceramic, quartz or the like is used as the material for the walking beam. Although it is possible with other heat resistant materials, the contamination during the heat treatment is relatively small.

And the movable beam 11 in embodiment of this invention has the support part 12 for supporting one to-be-heated object at four or more points as shown in FIG. As the height of this support portion, for example, four support portions having the same height of about 1 mm can be provided. However, as long as it is indirectly supported by the movable beam 11, the effect of the present invention can be exhibited at any height.
Thereby, when conveying the to-be-heated object W, the contact area of the movable beam 11 and the to-be-heated object W becomes small, and it can prevent that an extreme temperature difference arises in the contact part vicinity of the to-be-heated object W. For this reason, the damage by the temperature difference to the to-be-heated material W can be reduced, and a crack can be prevented effectively.
At this time, it is preferable to provide two support portions 12 on each side of the transport direction on the movable beam 11 that supports the article W to be heated. Thereby, one to-be-heated object can be supported by a total of four or more points, the load of the to-be-heated object W is disperse | distributed effectively, and the stable conveyance is possible.

Furthermore, when the solar cell element is manufactured, since the object to be heated is supported by points, there is almost no interference with the portion where the electrode material is applied, and good baking can be performed.
In addition, as for the fixed beam 61, as shown in FIG. 6, it is preferable to provide a support portion 12 that supports four or more points when one object to be heated is placed. Thereby, even when it is mounted and held on the fixed beam 61, the crack of the article to be heated W can be efficiently prevented, and good heat treatment can be performed.

  Moreover, the movable beam 11 in the embodiment of the present invention has a slip-off preventing means 13 as shown in FIG. In the present invention, the object to be heated W is transported in a state where it is supported at points, and therefore, it is likely to become unstable and may slide down. For this reason, by providing the movable beam 11 of the present invention with the slip prevention means, it is possible to realize both good heat treatment with less cracking and stable conveyance without slipping.

  As the slip-off preventing means 13 of the present invention, a stopper provided behind the object to be heated W as shown in FIG. With such a stopper, the article to be heated W often slides backward during conveyance, so that sliding can be effectively prevented. If the stopper is higher than the height when the object to be heated is placed, the stopper can exhibit a slip-off preventing function. As a method of providing the stopper, for example, the shape of the walking beam itself can be changed. Alternatively, the stopper can be provided by making a hole in the walking beam and inserting a rod-shaped object.

As a shape of said support part 12 and / or slipping prevention means 13, it can be set as a cylindrical rod-shaped body. If the support part 12 is cylindrical when the object to be heated W is placed, the center of the support part 12 has no contact part with the object to be heated W, so that the contact area can be further reduced. In addition, stress concentration due to the load of the object to be heated can be reduced.
Moreover, the same thing as the support part 12 can be utilized also about the sliding-off prevention means 13.

  Further, the material of the support portion 12 and / or the slip-off preventing means 13 can be ceramic. Thus, when the material of the walking beam is a material having a low coefficient of thermal expansion such as quartz, for example, a hole is provided in the walking beam, and when the heating beam is not heated, a ceramic cylindrical rod-shaped body or the like is used. By inserting the ceramic, the ceramic is thermally expanded and firmly fixed by heating performed during conveyance. Thus, if it is a ceramic, it can be attached by a simple method, and can provide the support part 12 and / or slipping prevention means 13 with high heat resistance and little contamination.

(Example)
When 500 semiconductor substrates for solar cells were heat-treated by the heat treatment apparatus of the present invention having the walking beam as shown in FIG. 1, neither cracking nor sliding occurred during the heat treatment. In the case of a heat treatment apparatus using a normal walking beam conveyance system, cracking or slipping occurs in about 2%, and it has been found that the effect of the present invention can be exhibited.

  As mentioned above, if it is the heat processing apparatus using the walking beam of this invention, the crack of the to-be-heated material at the time of heat processing can be prevented rather than the heat processing apparatus using the conventional walking beam, Sliding during transportation can also be effectively prevented. Thereby, it is possible to reduce the defect rate and the crystal cost during firing of the semiconductor substrate, particularly in the manufacture of solar cell elements.

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is a side view of the state by which the to-be-heated material was mounted on the walking beam in embodiment of this invention. (A) It is a cracking method when cracked in the crystal orientation of the object to be heated. (B) How to crack the object to be heated when heat-treated by a walking beam conveying heat treatment apparatus. It is a figure which shows the form of the conventional walking beam. It is a side view of the state by which the to-be-heated material was mounted on the conventional walking beam. It is a figure which shows one Example of the heat processing apparatus using the walking beam conveyance system in embodiment of this invention. (A) It is a side view of the state by which the to-be-heated material was mounted on the fixed beam. (B) It is a side view of the state in which the to-be-heated object was mounted on the movable beam.

Explanation of symbols

11, 32 ... movable beam, 12 ... support part, 13 ... slip-off prevention means,
31, 61 ... fixed beam, 51 ... transport device, 52 ... walking beam,
53a, 53b, 53c ... heater,
54a, 54b, 54c ... heat treatment furnace, 55 ... heat treatment apparatus,
W: Object to be heated.

Claims (6)

At least in the heat treatment apparatus that heats the object to be heated by being transported in a heat treatment furnace having a heater and passing through the heat treatment furnace by a walking beam that is driven by a transport device.
At least the walking beam has a support part for supporting at least four points when placing the one object to be heated, and has a means for preventing the object to slide off. A heat treatment device characterized.   2. The heat treatment apparatus according to claim 1, wherein the slip prevention means is a stopper provided on the walking beam at a rear side of a support portion of the object to be heated.   The support part is provided with at least two support parts for placing the one object to be heated on both sides in the transport direction, thereby supporting one object to be heated at a total of four or more points. The heat treatment apparatus according to claim 1, wherein the heat treatment apparatus is a heat treatment apparatus.   The heat treatment apparatus according to any one of claims 1 to 3, wherein the support portion and / or the slip prevention means is a cylindrical rod-shaped body.   The heat treatment apparatus according to any one of claims 1 to 4, wherein a material of the support portion and / or the slip-preventing means is ceramic.   The heat treatment apparatus according to any one of claims 1 to 5, wherein the heat treatment apparatus is for firing a semiconductor substrate coated with an electrode material in the manufacture of a solar cell element.

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