JPH04113650A - Method for unloading in heat treatment process - Google Patents

Abstract

PURPOSE:To prevent a wafer from damaging and cracking, by providing a first sensor for sensing whether any object to be processed is stored in carriers or not and a second sensor for sensing whether the objects to be processed are stored properly in the carriers or not. CONSTITUTION:In a base 31 for placing carriers, provided are a first sensor 32 for sensing whether any wafer is stored in four carriers 2 or not, and a second sensor 33 for sensing whether any wafer W protruded from the carriers 2 is stored in the four carriers 2 or not. The optical axis of light, which extends from a light emitting element 32A to a light receiving element 32B in the first sensor 32, is made to be so positioned, as shown by a point 41, that when any wafer W is not stored in all carriers 2, the light emitted from the light emitting element 32A can be received by the light receiving element 32B, and when even one wafer is stored in one of the carriers 2, the light transmitted from the light emitting element 32A to the light receiving element 32B is intercepted by the wafer thereof.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an unloading method in a heat treatment process.

[Conventional technology]

The manufacturing process of semiconductor devices includes a heat treatment process for oxidizing the surface of a semiconductor wafer and diffusing impurities, and a vertical or horizontal heat treatment furnace is used. The heat treatment equipment used in this heat treatment process includes a carrier stocker that stores carriers that can store multiple semiconductor wafers, which are objects to be processed, and a carrier stocker that stores multiple wafers and loads and unloads them into a heat treatment furnace. A boat station that places a boat to be loaded in a predetermined position, a carrier transfer device that transfers carriers between the stocker and the boat station, and a wafer transfer device that transfers wafers between the carrier and the boat. a replacement device,
It is equipped with a boat transport device that carries the boat into the heat treatment furnace and pulls out the boat that has been heat treated from the heat treatment furnace. Then, carriers storing a plurality of unprocessed wafers are sequentially loaded into the carrier stocker, and carriers storing processed wafers are sequentially taken out from the carrier stocker. During loading in the heat treatment process, a carrier transport device pulls out a plurality of carriers containing unprocessed semiconductor wafers from the carrier stocker and brings them to a predetermined position. Then, the semiconductor wafer in the carrier is transferred by a wafer transfer device to an empty boat made of quartz, for example, for heat treatment placed at a boat station. Then, the quartz boat loaded with a plurality of semiconductor wafers after the transfer is completed is moved from the boat station to a heat treatment furnace by a boat transfer device, the boat is inserted into the heat treatment furnace, and the semiconductor wafers are heat treated. Also, during unloading, the boat that has been heat treated is pulled out of the heat treatment furnace by the boat transfer device, placed on the boat mounting table of the boat station, and the semiconductor wafer that has been heat treated is transferred to a hot empty carrier. Then, the carrier that stores the processed wafer is transported to the carrier stocker by the carrier transport device.

[Invention or problem to be solved]

By the way, at the time of unloading, the carrier transport device transports a plurality of empty carriers in advance from the carrier stocker to a predetermined position near the boat station, and transfers the wafers from the boat to the carriers. However, at this time, if the carrier transport device or the carrier containing the wafers is being transported incorrectly, when the processed wafers are transferred from the boat to the carrier, they may collide with the wafers inside the carrier and damage the wafers. or fall off. In addition, even if the carrier transport device pulls out all empty carriers from the carrier stocker without error, when the transfer of wafers from the boat is completed, if some wafers are not properly stored in the carriers and are sticking out. When the carrier is transported into the carrier stocker by the carrier transport device, there is a risk that the protruding wafer may hit any part of the transport rod path and break. In view of the above points, it is an object of the present invention to provide an unloading method that can prevent damage and cracking of wafers.

[Means to solve the problem]

This invention transfers the processed objects from a boat carrying the processed objects that have been heat-treated to a transport tool capable of storing a plurality of processed objects, and transfers the processed objects to a plurality of transport tools after the transfer has been completed. In the unloading method of a heat treatment process, the object is moved to a stocker that accommodates the object, comprising: a first sensor for detecting whether or not the object to be processed is stored in the carrier; and a second sensor for detecting whether or not the object to be processed is correctly stored, and the first sensor confirms that the object to be processed is not stored in the transport tool, and then the boat is moved. The object to be processed is then transferred to the transport tool, and the second sensor confirms that the object to be processed does not protrude from the transport tool, and then the transport tool is moved to the stocker. shall be.

[Effect]

In this invention, as described above, after it is confirmed by the first sensor that no object to be processed is stored in the transport tool, the object to be processed is transferred from the boat to the transport tool. Therefore, when even one object to be processed is stored in the storage tool, the wafers are not transferred from the boat to the transport tool, so wafers will not collide with each other or fall off. Then, after it is confirmed by the second sensor that the object to be processed does not jump out from the transport tool, the transport tool is moved to the stocker. Therefore, when the carrier is transported to the stocker, the wafer does not jump out from the carrier at all, and the wafer is not damaged.

【Example】

Hereinafter, one embodiment of the boat transfer device according to the present invention will be described with reference to the drawings. First, a heat treatment apparatus to which the present invention is applied will be explained with reference to FIG. The carrier stocker 1 can accommodate a plurality of carriers such as wafer carriers 2, each of which accommodates, for example, 25 semiconductor wafers W, on the inside and the outside with the rail 4 in between. Then, carriers for storing unprocessed wafers are loaded onto the inside side, and carriers for storing processed wafers are stocked on the outside side. It is taken out from the outside side. Then, the carrier conveyance device 3 is guided by the rails 4,
It is attached so as to be slidably movable between the carrier stocker 1 and a predetermined position on the side of a boat mounting table 5 on which a heat-resistant wafer boat is mounted. Further, on the side of the rail 4, a boat platform 5 of a boat station is provided. A wafer transfer device 6 is provided between the boat platform 5 and the rail 4. For example, four carriers 2 can be placed on the carrier mounting table 31 of the carrier transport device 3, as shown in FIG. The wafers W in the carrier 2 are stored in the carrier 2 in a parallel manner with their main surfaces facing each other. The carriers 2 are placed on the carrier mounting table 31 in such a manner that all the wafers in the four carriers 2 are lined up in parallel. The carrier mounting table 31 includes a first sensor 32 for detecting whether or not a wafer is stored in the four carriers 2, and a first sensor 32 for detecting whether or not a wafer is stored in the four carriers 2, and a first sensor 32 for detecting whether or not a wafer is stored in the four carriers 2. A second sensor 33 is provided to detect whether or not there is. In this example, the first and second sensors 32 and 33 are optical sensors including a light emitting element such as a light emitting diode or a semiconductor laser, and a light receiving element such as a phototransistor or CCD. In this example, these first and second sensors 32
, 3B are attached as follows. That is, at one end of the carrier mounting table 31 in the longitudinal direction, with four carriers 2 in between, there is a section 3 for mounting the light emitting element.
4 is provided at the bottom of the section 34.
The light emitting element 32A of the second sensor 32 is mounted on the upper part of the mounting section 34, and the light emitting element 33A of the second sensor 33 is mounted on the upper part of the mounting section 34, respectively. Further, a light receiving element mounting section 35 is provided at the other end of the carrier mounting table 31, and a light receiving element 32B of the first sensor 32 is mounted at the lower part of this mounting section 35.
However, the light emitting element 3 of the second sensor is attached to the upper part of the part 35.
3B are attached to each. Then, the respective light receiving elements 32B and 33B are connected to the light emitting elements 32A and 33A.
A light emitting element and a light receiving element are provided facing each other so as to receive light from the light emitting element and the light receiving element. In this facing relationship, the surfaces may be parallel to each other or may be located on oblique surfaces. In this example, as shown in FIG. 3, the carrier 2 is shaped so that when the wafer W is stored, the upper end and lower end of the main surface of the wafer W are exposed to the outside. It is preferable that these sensors 32A and 32B have a structure that allows them to be attached and detached with one touch. The optical axis position of the light from the light emitting element 32A to the light receiving element 32B of the first sensor 32 is at point 41 in FIG.
As shown in FIG. 2, when no wafer W is stored in any of the carriers 2, the light from the light emitting element 32A can be received by the light receiving element 32B, and even one wafer W is stored in any carrier 2. When the wafer W
This is a position where light from the light emitting element 32A to the light receiving element 32B is blocked. Further, the optical axis position of the light from the light emitting element 33A to the light receiving element 33B of the second sensor 33 is as shown by a point 42 in FIG. 3 when the wafer W is correctly stored in the carrier 2. In this case, the light from the light emitting element 33A is transmitted to the light receiving element 33.
If the wafer W stored in the carrier 2 protrudes from the correct position, the wafer W can receive light at B.
This is the position where light from the light emitting element 33A to the light receiving element 33B is blocked. If such detection results in ambient light or noise, frequency selection (
Noise countermeasures can be taken by using a filter circuit). Further, in this example, the loading operation and the unloading operation are controlled by software, and as shown in FIG. 4, a control device 50 including a microcomputer for the control is provided. The sensor outputs of the first and second sensors 32 and 33 are supplied to this control device 50, and this control device 50 controls the drive of the wafer transfer device 6, the carrier transfer device 3, and further the boat transfer device 8. be done. Next, the loading operation and unloading operation in this device will be explained below. At the time of loading, a robot (not shown) places, for example, four inner carriers 2 on the carrier 31 of the carrier carrier 3. After confirming that there is no wafer W flying out from the carrier 2 based on the detection output of the second sensor 33, the control device 50 drives the carrier transfer device 3 to move the wafer W to a predetermined position on the side of the hoard mounting table 5. These carriers 2 are transported to the location. On the other hand, an empty boat 7 is positioned and placed on the boat mounting table 5. Then, the wafer transfer mechanism 6 transfers the wafer W from the carrier 2 to the empty boat 7 on the boat mounting table 5. When the transfer of the wafer is completed, the wafer is carried into a heat treatment furnace by the boat 7 or a boat transfer device (not shown), and heat treatment is performed. In the case of a multistage furnace configuration including a plurality of heat treatment furnaces, the control device 50 drives the carrier transport device 3 to return the four empty carriers 2 to the carrier stocker 1 after the transfer. At this time, it can be detected from the detection output of the first sensor 32 that the four carriers 2 are empty. Then, the carrier 2 containing another unprocessed wafer is placed in the same manner as described above, these are transported to the side of the boat mounting table 5, the wafer W is transferred to the boat 7, and the wafer W is transferred to the boat 7 by the boat transport device. Transfer to another heat treatment furnace. Then, when the heat treatment is completed in any of the heat treatment furnaces, unloading is performed. During this unloading, the boat 7 that has undergone heat treatment is
is pulled out from the heat treatment furnace, and the boat 7 is placed and positioned on the boat mounting table 5 by the boat transfer device. On the other hand, the empty carrier 2 is being transported from the carrier stocker 1 to the side of the boat mounting table 5 by the carrier transport device 3 . In this state, the control device 5o checks the output of the first sensor 32 of the carrier transport device 3, and determines whether all four carriers are empty or not. And the light receiving element 32B
is receiving light from the light emitting element 32A, and when it is confirmed from the output of the light receiving element 32B that no wafer is stored in the four carriers, the control device 50 sends the wafer transfer device 6 to the wafer transfer device 6. The processed wafers are transferred from the boat 7 to the carrier 2 by the wafer transfer device 6. In this way, the wafer is transferred after confirming that there is no wafer W stored in the carrier 2, so there is no chance of the wafer being damaged due to collision or falling and breaking the wafer. . When the transfer is completed, the control device 5o checks the sensor output of the second sensor 33, and determines whether all the wafers are properly stored in the carrier and there are no protruding wafers. Then, the light receiving element 33B is the light emitting element 33
After receiving the light from A and confirming that there are no wafers protruding from the carrier 2, the control device 5o drives the carrier transport device 3. Then, the carrier transport device 3 moves to the carrier stocker 1. Thereafter, the carrier containing the processed wafer is transferred to the outside of the carrier stocker 1 from a robot (not shown) or carrier transfer device 3. In this way, the carrier is transported to the carrier stocker 1 after confirming that the wafer W has not jumped out from the carrier 2, so there is no possibility that the wafer W that has flown out will collide with and be damaged on the transport route. The above example is an example in which a plurality of carriers are placed side by side on a horizontal table, but the carriers taken out from the carrier stocker are transported by a carrier transport device (not shown) as shown in FIG. With the main surface of the boat W being horizontal, it is transported to a carrier station 62 where a plurality of carriers 61 are stacked and mounted vertically, and from the carrier 61 of this carrier station 62, the boat mounting table 63 is loaded. On the boat 64 standing vertically on top,
Of course, the present invention can also be applied to a case where the wafer transfer device 65 transfers wafers W one by one, for example. In this example, the first sensor for detecting the presence or absence of the wafer W may not be shown or may be provided on each carrier mounting table 62C of the carrier station 62. Further, the second sensor for detecting the protrusion of the wafer W includes a light emitting element 37A provided above a plurality of carriers 61 stacked vertically in the carrier station 62, and a light emitting element 37A provided at the bottom side. Light receiving element 3'7B
A wafer protrusion can be detected in common to a plurality of carriers by providing a wafer protrusion. In the example shown in FIG. 2, one set of optical sensors 32
, 33, it is possible to detect whether all of the plurality of carriers are empty and whether or not there is a protruding wafer, but the first and second sensors 32,
A sensor having the same role as 33 may be provided. However, as in the example shown in FIG.
, 33 is better in terms of sensor installation space and cost. Further, as the first and second sensors, not only optical sensors but also capacitive sensors and other various sensors can be used. For example, when a weight sensor is used, if the object to be processed is large, such as an 8-inch wafer, the presence or absence of the object to be processed can be detected with high accuracy. Furthermore, the object to be processed is not limited to semiconductor wafers;
Needless to say, various materials such as a CD substrate are applicable.

【Effect of the invention】

As explained above, according to the present invention, when unloading in the heat treatment process, the first sensor confirms that the carrier is empty, and then the object to be processed is transferred from the boat. There is no possibility that processing bodies collide with each other. In addition, after the transfer is completed, after confirming with the second sensor that there are no objects to be processed sticking out of the carrier,
Since the carrier is transferred to the stocker, it is possible to prevent the object to be processed from colliding with somewhere during the transfer of the carrier and being broken.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an outline of an example of a heat treatment apparatus according to the present invention, FIG. 2 is a side view of an example of a carrier conveying apparatus, and FIG.
The figure is a diagram for explaining the state of wafer storage in the carrier and the installation positions of the first and second sensors, Figure 4 is a block diagram of an example of the drive control section of the heat treatment equipment, and Figure 5 is the object of the present invention. It is a figure which shows another example. 1; carrier stocker 2: carrier 3; carrier transport device 5; boat mounting table 6; wafer transfer device 7; boat 31: carrier mounting table 32; first sensor 33; second sensor 32A, 33A, light emitting element 32B , 33B, light receiving element 34; light emitting element mounted in section 35; light receiving element mounted in section W; semiconductor wafer

Claims (1)

[Scope of Claims] The object to be processed is transferred from the boat carrying the object to be processed which has been heat-treated to a transport tool that can store a plurality of objects to be processed, and the object to be processed is transferred to a transport tool which has completed the transfer. In an unloading method for a heat treatment process in which a transport tool is moved to a stocker that accommodates the transport tool, the transport tool includes: a first sensor for detecting whether or not the object to be processed is stored in the transport tool; and a second sensor for detecting whether or not the object to be processed is correctly stored in the carrier, and confirming that the object to be processed is not stored in the transport tool by the first sensor, The object to be processed is transferred from the boat to the transport tool, the second sensor confirms that the object to be processed does not jump out of the transport tool, and the transport tool is moved to the stocker. An unloading method in a heat treatment process characterized by: