JPH01230229A - Method and apparatus and loading and unloading body under heat treatment into and out of furnace - Google Patents

Abstract

PURPOSE:To make the relative positions of a fork and wafers in loading and unloading identical, by supporting a boat on which the wafers, i.e., bodies under heat treatment, based on the quantity of a dynamic state that is measured beforehand. CONSTITUTION:A loading/unloading means is set so that the quantity of a dynamic state that is measured beforehand is obtained. Wafers 2 are mounted on a boat 3. The boat 3 is supported in a cantilever mode with a fork 6 of the loading/unloading means. The boat 3 is loaded into a process tube 28 wherein heat treatment is performed. At the time of unloading, the boat 3 is supported in a cantilever mode with the fork 6 under the state wherein the measured quantity of the dynamic state of the fork 6 agrees with the value that is measured beforehand. In this method, the relative positions of the fork and the wafers in loading and unloading become identical. The succeeding automatic control after the heat treatment is carried out readily and securely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method and apparatus for transporting objects to be heat treated into and out of a furnace.

(Prior Art) Semiconductor devices such as ICs or LSIs are produced by sequentially processing a wafer cut from an ingot, performing one surface processing treatment, thermal oxidation treatment, impurity diffusion treatment, film deposition treatment, etching treatment, etc. Manufactured through multiple steps. In these manufacturing steps, semiconductor wafers are repeatedly subjected to heat treatment multiple times.

Generally, multi-stage furnaces 1, for example, four-stage furnaces stacked one above the other, are employed as heating furnaces for heat treatment of semiconductor wafers. Process tubes are installed horizontally in each furnace of the multi-stage furnace, while a soft landing device is installed in front of each furnace mouth, and boats loaded with wafers (hereinafter referred to as wafer boats) are placed in each soft landing device. It is inserted into each process tube by a landing device.

Soft landing devices for loading and unloading boats into and out of the process tube of a furnace are described in Japanese Patent Publication No. 62-3571, U.S. Pat. No. 4,008,815, and U.S. Pat. No. 4,468,195. are known. These soft landing devices have a fork that extends in the axial direction of the furnace (referred to as the X-axis direction) toward the furnace mouth. The fork.

The main body is cylindrical, and the tip of the wafer boat is a
It is shaped so that it can be placed.

In addition, the soft landing device
an xI111 drive mechanism for advancing or retracting along an axis;
It has a θ-axis drive mechanism that swings the tip of the fork up and down, a controller that controls the movement of the fork, and a computer system that backs up the controller based on predetermined programming.

When loading a wafer boat into a furnace using a conventional soft landing device, the X-axis drive mechanism moves the fork forward a predetermined distance in the X-axis direction, and the θ-axis drive mechanism gently lowers the fork tip, allowing the wafer boat to Transfer the boat from the fork to the process tube. Also,
To unload the wafer boat in the furnace, insert the fork into the process tube, gently lift the wafer boat with the tip of the fork, and move the fork back a set distance in the X-axis direction. During these series of loading/unloading operations, the fork and wafer boat are controlled so as not to rub against the inner wall of the process tube, thereby preventing generation of quartz powder due to rubbing against each other.

(Problems to be Solved by the Invention) However, in the conventional method of loading and unloading wafer boats, the wafer boat is tilted with respect to the process tube when loading the boat using the θ-axis drive mechanism, or the X-axis drive Due to the presence of operational errors in the mechanism, the relative position between the fork and the wafer boat is different during loading and unloading. For this reason, the carrying position of the wafer boat on the fork changes between loading and unloading.
There has been a problem in that mechanical measures cannot be taken when the wafer boat is transported by an automatic transport mechanism in the next process (process following the heat treatment process).

This invention has been made to improve the above-mentioned problems, and provides a boat loading and unloading method that can maintain the relative position of the boat and fork constant when loading and unloading the boat, and a method for loading and unloading the boat. To provide a soft landing device that allows a boat to be loaded/unloaded into a furnace without substantially changing the carrying position of the boat on the fork.

[Structure of the invention]

(Means for Solving the Problems) This invention provides a mechanical state that acts on the loading/unloading means when the object to be heat treated is cantilever-supported by the loading/unloading means before loading the object into the furnace. The quantity is measured in advance, and this is used as the first measurement value, and furthermore, the mechanical state quantity that acts on the loading/unloading means when the heat-treated object after heat treatment is cantilever-supported by the loading/unloading means. is measured, this is taken as a second measured value, the first and second measured values are compared with each other, and the load/unloading means is applied until the second measured value matches the first measured value. A method for loading and unloading a heat-treated object into and out of a furnace, comprising correcting the holding position of the heat-treated object and unloading the heat-treated object from the furnace when the two match;
and a means for transporting the object to be heat treated while supporting it in a cantilever manner and loading or unloading it into a furnace, and a means for measuring the amount of mechanical state acting on the loading/unloading means when the object to be heat treated is supported in a cantilever manner. and,
means for comparing the measured values of the mechanical state quantity before and after the heat treatment; and means for correcting the holding position of the object to be heat treated by the loading/unloading means until the two values match.

An object of the present invention is to obtain a device for taking a heat-treated object into and out of a furnace, characterized by having the following features.

(Function) According to the present invention, before the object to be heat treated is loaded into the furnace, when the object to be heat treated is cantilever-supported by the loading/unloading means, the amount of mechanical state that acts on the loading/unloading means is calculated. The mechanical state quantity is measured in advance, and the mechanical state quantity is also measured after the heat treatment, the surface measurement values are compared with each other, and the holding position of the heat-treated object by the loading/unloading means is corrected until the two match. A method for unloading an object to be heat treated from a furnace when the two match, a means for transporting an object to be heat treated while supporting it in a cantilever manner, and loading or unloading the object into the furnace, A means for measuring a mechanical state quantity acting on the loading/unloading means; a means for comparing the measured values of the mechanical state quantity before and after the heat treatment; and (1) a means for loading/unloading the object to be heat treated until both values match. means for correcting the holding position according to the
The relative position of the boat and fork can be kept constant during loading and unloading of the boat, and the hoard can be loaded/unloaded into the furnace without substantially changing the carrying position of the boat on the fork. can.

(Example) An example in which the present invention is applied to a heating furnace system will be described below with reference to the drawings.

As shown in FIG. 1, the heating furnace apparatus 1 is a multistage furnace in which single furnaces are stacked vertically in four stages, and a plurality of process tubes are inserted horizontally into each furnace. This heating furnace apparatus 1 is for oxidizing and diffusing silicon wafers.

A unit 4 for loading and unloading the boat is connected to the furnace port 1 of the heating device 1.
It is installed in front of a. Unit 4 is.

It is comprised of a filter unit 4a having an air filter, and a unit 4b for transporting, for example, a quartz glass boat 3 loaded with a large number of wafers 2 into and out of the furnace 1 via the furnace opening 1a. Unit 4b is column 4 of 4 rows.
c, and one end of each shelf 4c communicates with the respective furnace opening 1a. A soft landing device 5 having a fork 6 made of quartz glass is provided on each shelf 4c.

The fork 6 extends on the extension line of each furnace axis, and has a cylindrical portion 7 on its base end side and a boat support portion 8 on its distal end side.

An elevator device 9 is provided on the front side between the heating furnace device 1 and the pedestal 4. Arm 9a of elevator device 9
A member 9b for transferring the boat 3 on the front stage to the support portion 8 of the fork 6 is provided at the tip.

The elevator device 9 has a mechanism for moving one member 9b along the X-axis and the Z-axis, respectively.

A stage on which the wafer cassette 11 and wafer boat 3 are placed is provided in front of the lowermost shelf 4C of the unit 4b. A handling device [10] is provided further in front of this stage. Handling equipment @10
has a mechanism for taking out the wafers 2 from the cassette 11 and a mechanism for transferring the taken out wafers 2 to the boat 3.

The soft landing device 5 will be explained with reference to FIG. Note that the guide rails 13a and 13b of the soft landing device M5, whose forks are not shown in FIG. 2 for convenience, are fixed on the base member 12 of 1i4c. The drive shaft 15 is connected to the rail 13
a and 13b, one end is pivotally connected to the stopper member L5a, and the other end is connected to the gear 18.

Guide rails 13a, 13b and drive shaft 1
5 extend parallel to each other along the X axis, and each passes through each of the first slider 14 and the second slider 27.

The timing belt 17 is connected to the gear 18 and the motor 1 described above.
The hook is passed between the 6 drive gears 16a.

The drive shaft 15 and the first slider 14 are connected by a transducer 15b. The converter 15b has a built-in friction member that slides on the shaft 15.

The friction member has the function of converting the rotational motion of the shaft 15 into a sliding linear motion.

In addition, the second slider 27 also has a similar converter (not shown).
have. This second slider 27 is.

This is to support the fork on the tip side.

A support portion 19 for cantilever-supporting the fork 6 is provided with a first
is provided above the slider 14. This fork support part 19 is provided with a first
a support member 20 and a support shaft 22 on the first support member 20.
In FIG. 6, the second support member 22 is provided to be swingable via a, and the third support members 23a and 23b are provided on the second support member 22. ,
The third support members 23a and 23b are shown in an exploded state. When the upper member 23a is placed over the lower member 23b and the bolt 23c is tightened, the rear end of the fork 6 (not shown) is held between the upper and lower members 23a and 23b. In this case, the rearmost ends of the fork 6 and the rearmost ends of the third members 23a, 23b are aligned. Note that the third lower member 23b is fixed to the second support member 22 by bolts 23d.

Further, the rear end portion of the second support member 22 extends rearward than the rear end portions of the third support members 23a and 23b, and the eccentric cam 21 is in contact with the upper surface of the rear end portion of the member 22. There is.

Both ends of the eccentric cam 21 are rotatably supported by a pair of brackets 21a, and one end is connected to a shaft 21b. This shaft 21b is connected to a drive shaft of a motor 25 via a speed reduction mechanism (not shown) having a worm gear.

A pressure sensor (not shown) is connected to the cam 21 and the bracket 2.
1a, and from the force 1121 to the bracket 2
The moment of force transmitted to 1a is adapted to be detected.

Next, the swinging mechanism of the fork 6, that is, the θ-axis drive mechanism will be described with reference to FIG.

The swinging mechanism of the fork 6 is a lever mechanism that uses the support shaft 22a as a fulcrum, the contact portion of the cam 21 and the member 22 as a point of force, and the boat support portion 8 as a point of action. That is, when the eccentric cam 21 is rotated, the boat support section 8, which is the point of action, swings up and down.

Next, the mutual positional relationship between the fork and the process tube when loading/unloading a boat will be explained with reference to FIGS. 4 to 6.

As shown in FIG. 4, the fork 6 is on standby so that the boat support part 8 faces the insertion opening of the process tube 28. When the fork 6 is advanced, the boat support section 8 is inserted into the process tube 28, as shown in FIG. As shown in Figure 6.

The boat support part 8 is the soaking part 28a of the process tube 28.
The fork 6 is stopped at the position, and the boat (not shown) is loaded/unloaded.

As shown in FIG. 7, the boat 3 is connected to the process tube 28
The wafer 2 and the process tube 28
The distance from the inner wall is almost uniform over the entire circumference.

Next, the flowchart 1- in FIG. 8 and the flowcharts 9 to 14 in FIG.
While referring to the cross-sectional schematic diagram in the figure, the boat 3 is moved to the process tube 2 of the furnace using the soft landing device 5 described above.
8 will be explained in detail.

A boat 3 loaded with a large number of silicon wafers 2.

The member 9b of the elevator device 9 is transferred to the boat support portion 8 of the fork 6. In this case, wafer 2 and boat 3
The total weight of the fork 6 is about 5 to 10 kg, and the length of the fork 6 is about 200 to 300 cm. The soft landing device 5 is turned on to start the loading/unloading operation of the wafer boat 3.

First, step 1 of detecting and measuring, with a sensor, the moment A of the force transmitted to the force point of the fork support portion 19 (the contact portion between the cam 21 and the member 22) when the wafer boat 3 is cantilever-supported by the fork 6. (Sl).

Step 2 (52) of storing this measured value M1 in the memory of the computer system.

Next, move the fork 6 in the X-axis direction, insert the boat support part 8 into the process tube 28, and stop when the wafer boat 3 is located in the soaking part 28a, as shown in FIG. .

Next, by driving the motor 25 of the θ-axis drive mechanism.

The eccentric cam 21 is rotated by a predetermined number of rotations, and the boat support part 8 is lowered as shown in FIG.

After transferring the wafer boat 3 from the support section 8 to the process tube 28, as shown in FIG.
The wafer boat 3 is moved back in the axial direction, leaving only the wafer boat 3 in the process tube 28.

The furnace opening 1a is closed, and the wafer 2 is subjected to oxidation diffusion treatment under predetermined temperature, time, and atmospheric conditions.

After the heat treatment is completed, the fork 6 is moved forward in the XIPI direction 11 by the same distance as during loading, and the boat support part 8 is positioned at the wafer boat 3, as shown in FIG.

As shown in FIG. 13, the wafer boat 3 is lifted by the fork 6, and when lifted,
Step 3 (S:
3) At this time, the weight of the wafer boat 3 before and after the heat treatment is substantially the same. For example, when IIJM polysilicon is deposited on 150 6-inch diameter wafers by CVD, a weight increase of about 12 grams is observed before and after the process, but this is negligible from the overall weight of the wafer board and fork. This is a possible number.

The memory value H2 in which the data is stored is called, the detected moment M2 and the memory value M1 are compared with each other (step 4), and if they match, as shown in FIG.
Step 5 (S5) of retracting the fork 6 and taking out the wafer boat 3 out of the furnace.

In step 4 (S4), the detected moment M
2 is different from the memory value M1, step 6 of lowering the wafer boat 3 into the process tube 28, correcting the stop position of the fork 6, and lifting the wafer boat 3 again with the fork 6 (S6); In other words, until the memory value and the detected moment M□ match, step 3
→ Repeat step 4 → step 6 → step 3.

Finally the memory value is detected moment! 112, the process proceeds to step 5, where the wafer boat 3 is taken out of the furnace, and the series of operations ends.

In the above embodiment, the moment of force at the force point of the fork support member is detected, but the present invention is not limited to this, and a strain gauge may be provided on the fork support member 22 to detect the deflection of the support member 22. You can.

Further, in the above embodiment, a θ drive mechanism having an eccentric cam is used as the swinging means of the fork, but the present invention is not limited to this, and other swinging mechanisms such as a lever crank mechanism may also be used. The soft landing device also includes an X-axis drive mechanism (fork forward/backward mechanism) and a θ drive mechanism (fork swing mechanism). In this case, it is preferable that the X-axis drive mechanism and the θ drive mechanism be controlled by a computer system.

It is preferable that a computer system perform calculations based on the measured data of the mechanical state quantity, and correct the lifting position of the wafer boat by the fork based on the calculation results.

Furthermore, it is preferred that the XM drive mechanism of the soft landing device has a converter for converting the rotational movement of the drive shaft into a linear movement of the slider.

In this case, a ball screw or the like can be used as the drive shaft, but it is preferable to use a friction shaft without threaded grooves.

According to the above embodiment, the relative position between the boat and the fork can be kept constant when lifting the boat. Therefore, the wafer boat can be taken in and out of the furnace without the boat and fork coming into contact with the inner wall of the process tube, and it also prevents accidents caused by misalignment between the wafer and the automatic transport mechanism during automatic wafer transport after the next process. does not occur. Therefore, wafer damage accidents can be effectively avoided, and the yield of wafers can be improved. Furthermore, the cleanliness within the room can be maintained at a high level.

〔Effect of the invention〕

According to the present invention, the relative positions of the fork and the boat can be made substantially the same at both the loading and unloading points, so that the wafers can be handled reliably by the automatic machine in the next process and thereafter. It has an effect that is easy to achieve.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing ancillary equipment near the furnace mouth of a heating furnace system for explaining one embodiment of the method and apparatus of the present invention, and FIG. 2 is a soft landing device (
FIG. 3 is an explanatory diagram showing the fork (not shown); FIG. 3 is an explanatory diagram showing the fork in a direction perpendicular to its longitudinal direction; Figure 6 is an explanatory diagram of the fork and process tube viewed from the longitudinal direction, in order to explain the mutual positional relationship between the fork and the process tube at each stage in Figure 1, and Figure 7 is an explanatory diagram of the fork and process tube inserted into the process tube. An explanatory view of the fork and boat viewed from the longitudinal direction, FIG. 8 is a flowchart showing the operation of the luff 1-landing device in FIG. 1, and FIGS. 9 to 11 show loading the boat in FIG. 1 into the process tube. In order to explain a series of operations when the boat shown in FIG. For illustrative purposes, FIG. 2... Wafer 3... Boat 5... Soft landing device 6... Fork 8... Boat support part 10
...Handling device 11...Cassette 28...
・Process tube Fig. 4 Fig. 5 8 Fig. 6 Fig. 8

Claims (2)

[Claims] (1) Before loading the object to be heat treated into the furnace, measure in advance the amount of mechanical state that acts on the loading/unloading means when the object to be heat treated is cantilever-supported by the loading/unloading means. is the first measurement value, and further, when the heat-treated object is cantilever-supported by the loading/unloading means, the mechanical state quantity acting on the loading/unloading means is measured, and this is determined as the second measurement value. and comparing the first and second measured values with each other, correcting the holding position of the object to be heat treated by the loading/unloading means until the second measured value matches the first measured value, A method for loading and unloading a heat-treated object into and out of a furnace, which comprises unloading the heat-treated object from the furnace when the two match. (2) Measuring the means for transporting the object to be heat treated while supporting it in a cantilever manner and loading or unloading it into the furnace, and the amount of mechanical state that acts on the loading/unloading means when the object to be heat treated is supported in a cantilever manner. and the means to
A heat-treated object characterized by comprising means for comparing the measured values of the mechanical state quantity before and after the heat treatment, and means for correcting the holding position of the heat-treated object by the loading/unloading means until both values match. A device that moves bodies into and out of the furnace.