JPH08202421A - Robot control method - Google Patents

Abstract

PURPOSE: To provide a robot control method which can correct a position shift without reteaching all chambers. CONSTITUTION: If a substrate conveying robot has a position shift during conveying operation, reteaching is done at a desired conveyance place 1011 , an error swivel movement quantity ΔRa1 (or ΔRb1 ) and an error expansion/ contraction movement quantity ΔEa1 (or ΔEb1 ) at this conveyance place 1011 are calculated from the current movement quantity and storage contents and converted according to the positions of respective conveyance places on the basis of the structure and cause of the position shift of the substrate conveying robot, thereby correcting storage contents (Rn , En ) indicating the positions of the respective conveyance positions. When a place where a recovery is easy even in case of exposure to the atmosphere is selected as the conveyance place where the reteaching is performed, the time required for the recovery to the original state can greatly be shortened after the position shift is corrected.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] The present invention relates to a robot control method in which a transfer position is stored by teaching and a substrate transfer operation is performed, and particularly, a control of a substrate transfer robot having a place for transferring a substrate in a chamber that is not exposed to the atmosphere. Regarding the method.

[0002]

2. Description of the Related Art In recent years, a multi-chamber type semiconductor manufacturing apparatus has been used for sputtering and etching. As an example of such a multi-chamber type apparatus, a semiconductor manufacturing apparatus 1 shown in FIG.
00 will be briefly described.
Is centered on the transfer chambers 103 ₁ and 103 ₂ and four processing chambers 101 ₂ , 101 ₃ , 101 ₅ , and 10 ₁₆ and the transfer chamber 1
03 _1, 103 and an intermediate chamber 101 ₄ connecting the _two, carrying the wafer, the cassette chamber 101 _1, 101 ₇ unloading is performed is arranged as a multi-chamber, the transfer chamber 103 _1, 103 ₂ and the A partition plate that can be opened and closed is provided between the cassette chambers 101 ₁ and 101 _7, and the transfer chambers 103 ₁ and 103 ₂ have high vacuum even when the cassette chambers 101 ₁ and 101 ₇ are exposed to the atmosphere. It is configured so that it can maintain its state. In addition, each processing chamber 101 ₁ , 101 ₂ , 1
01 _5, 101 ₆ and the transfer chamber 103 _1, 103 ₂ openable partition plates also between are respectively provided, the conveying chamber 10
Even when 3 ₁ and 10 3 ₂ are exposed to the atmosphere, each processing chamber 10
11 ₁ , 101 ₂ , 101 ₅ , and 10 ₁₆ are configured so that a clean atmosphere in a high vacuum state can be maintained.

At a position 105 near the center of the _two transfer chambers 103 ₁ and 103 ₂ , a substrate transfer robot 2 as shown in FIG. 1 is arranged.
When the cassette chamber 101 ₁ is set to a high vacuum state and a partition plate between the cassette chamber 101 ₁ and the transfer chamber 103 ₁ is opened, the wafer placed in the cassette chamber 101 ₁ is removed according to the contents taught in advance and a predetermined sequence. The transfer chamber 103 ₁
Each processing chamber 10 according to the locus indicated by the arrow.
1 _1, 101 _2, 101 _5, 101 ₆ carrying the wafer between the carry-out is performed, the processing chambers 101 _1, 101 _2, 101
_5, 101 treated wafer ₆ is taken out from the end to the cassette chamber 101 _7, the semiconductor processing equipment 100
The process work done at is finished.

The teaching operation for the substrate transfer robot 2 is performed when the semiconductor manufacturing apparatus 100 is installed. At the time of this teaching, each chamber is opened, the inside is exposed to the atmosphere, and the cassette chamber 10 is checked while observing the operation of the transfer robot 2.
11 ₁ , 10 ₁₂ and the processing chambers 101 ₁ , 101 ₂ , 10
This is performed by tentatively transporting the wafer to a predetermined transporting location within 1 ₅ and 10 _{16 and} storing the amount of movement at that time as the position of each transporting location. Then, in the actual transfer operation, the wafer is carried out and carried in between the respective transfer locations according to the stored contents. A general-purpose transfer robot that operates by such teaching can handle various chamber combinations, and if re-teaching is performed, additional chambers can be added without mechanical modification of the transfer system.
It has been widely used because of the advantage that it can be changed.

However, the frog leg arm and pickup provided in the transfer robot 2 may need to be replaced after maintenance. When such replacement is performed, the mounting position and the mounting angle are often slightly different from those before the replacement. If such a difference occurs, after the maintenance work is completed, even if the substrate transfer robot 2 performs the operation as taught, the wafer cannot be accurately transferred to the transfer location. If a large amount of positional deviation occurs between the wafer and the correct transfer place, it will hinder the processing of the wafer, and it has been necessary to correct this.

In view of this, in the prior art, when a positional deviation occurs, teaching is performed again for all the chambers in order to store the positions of the transfer locations in all the chambers including the processing chamber again. It was lost time.

However, rather than the loss time due to this re-teaching, the time required to restore the original high vacuum state again after the end of re-teaching is longer. Exposing each chamber placed to the atmosphere once is a problem.

In this case, for example, in the transfer chamber through which the wafer passes, the quality of the vacuum state required for the transfer chamber may be low. Therefore, it is not possible to recover the vacuum state of the transfer chamber to a level usable in the process operation. Although it is easy, once the processing chamber is exposed to the atmosphere, it takes a huge amount of time to recover the high-vacuum state of good quality to the extent that wafer processing is possible. The loss time for recovering the vacuum state of good quality is longer than the time required for the re-teaching work, and the throughput is seriously affected.

Particularly when the processing chamber is a sputtering chamber,
Since the target placed in the sputtering chamber is also exposed to the atmosphere, the target surface is oxidized, water is adsorbed, dust is adhered, etc. Without sputtering, the target could not recover its original performance and a solution was desired.

[0010]

SUMMARY OF THE INVENTION The present invention was created in view of the disadvantages of the above-mentioned prior art. The purpose of the present invention is to expose all the chambers to the atmosphere and re-execute them when a position displacement occurs in the transfer operation. It is an object of the present invention to provide a technique capable of correcting a position shift without teaching.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 is a robot main body provided with two rotary shafts, and is attached to the two rotary shafts. An arm portion having a link mechanism that rotates by the rotation in the same direction and expands and contracts by the rotation in the opposite direction, a substrate holding portion that is provided on the arm portion and forms a part of the link mechanism, and is held by the substrate holding portion. A robot control method for controlling a substrate transfer robot that transfers the substrate to a plurality of transfer locations arranged around the robot body, wherein the amount of rotation of the arm portion based on the origin return state of the arm portion is set. The turning movement amount is set, and the expanded / contracted amount is set to the expansion / contraction movement amount, and the substrate holding unit is temporarily moved to each of the transfer locations, and the turning movement amount and the expansion / contraction movement amount at that time indicate the position of each transfer location. Memory turning movement and memory Stored as reduced moving amount, in the substrate transfer robot according to the stored contents, actually in the robot control method of conveying the wafer to the respective conveying location,
When the return-to-origin state of the substrate holding unit changes and the wafer is transferred according to the stored contents, a positional deviation is corrected in a positional deviation correction step including the following steps. (1) A first step in which a reference point is set on the substrate holder according to the cause of the positional deviation and a transfer position corresponding to the reference point is set on a desired transfer location selected from the plurality of transfer locations. (2) A second step of forcibly moving the substrate holder so that the reference point is located on the transfer position. (3) A third step of detecting the turning movement amount and the extension / contraction movement amount when the forced movement is performed, and setting the corrected turning movement amount and the correction extension / contraction movement amount that correctly indicate the transport position. (4) From the difference between the values of the stored turning movement amount and the stored extension / contraction movement amount corresponding to the desired conveyance location, and the values of the corrected turning movement amount and the corrected extension / contraction movement amount, the positional deviation at the conveyance position is calculated. A fourth step of calculating the error turning movement amount and the error expansion / contraction movement amount shown. (5) Converting the error rotation movement amount and the error expansion / contraction movement amount obtained in the fourth step into values corresponding to each conveyance position according to the cause of the position deviation, and showing the position deviation at each conveyance position. A fifth step of obtaining the error turning movement amount and the conversion error expansion / contraction movement amount. (6) The converted error swing movement amount and the converted error expansion / contraction movement amount obtained in the fifth step are respectively added to the stored rotation movement amount and the stored expansion / contraction movement amount corresponding to each of the transport positions,
A sixth step of correcting the stored content indicating each transport position.

The invention according to a second aspect is the robot control method according to the first aspect, wherein each of the transfer locations is individually in a vacuum state, and the desired transfer location has a high-quality vacuum state. In the robot control method according to claim 1, the present invention according to claim 3 is characterized in that, when a transporting place where the above is not required is selected and the positional deviation is corrected, other transporting places are not exposed to the atmosphere. A sensor for detecting the reference point is provided at the carrying position to correct the positional deviation without exposing each carrying place to the atmosphere.

[0013]

A substrate holding portion which is attached to two rotating shafts of the robot body, and which pivots when the two rotating shafts rotate in the same direction and which expands and contracts by rotating in the opposite direction, constitutes a part of a link mechanism. If the substrate is held by and the rotations of the two rotary shafts are controlled, the substrate can be freely moved to a plurality of transfer places arranged around the robot body.

When the movement of the substrate is carried out, the substrate holding is carried out when the amount of rotation of the arm is taken as the amount of turning movement and the amount of expansion and contraction is taken as the amount of expansion and contraction with reference to the origin return state of the arm. If the part is temporarily moved to each of the transfer places and the turning movement amount and the expansion / contraction movement amount at that time are obtained, the value becomes two components of a plane position vector indicating the position of each transfer place. Is stored as a memory turning movement amount and a memory expansion / contraction movement amount respectively, and according to a predetermined sequence,
If the transfer robot is actually operated based on the stored contents, the substrate can be automatically transferred to each transfer location.

However, if maintenance work or the like is performed and the return-to-origin state of the substrate holder changes, a positional deviation occurs even if the substrate is transported based on the stored contents.
The board cannot be correctly transferred to each transfer location.

In order to correct such positional deviation,
Since it is necessary to set a reference point when making corrections, first set a reference point on the substrate holding part according to the cause of the positional deviation, and set it on a desired transfer location selected from the plurality of transfer locations. A transport position corresponding to the reference point is determined (first step).

Then, when the substrate holding portion is forcibly moved so that the reference point is located on the transfer position and the transfer is performed without positional deviation (second step), the turning required at this time is performed. Since the movement amount and the extension / contraction movement amount are values that correctly indicate the reference point after the change in the origin return state, the values are used as the corrected turning movement amount and the corrected extension / contraction movement amount (third step), and the values thereof are set. And calculating a difference between the stored turning movement amount and the stored expansion / contraction movement amount value corresponding to the transport position,
Assuming that the error turning movement amount and the error extension / contraction movement amount are respectively, the values of the error turning movement amount and the error extension / contraction movement amount are error vectors indicating the magnitude and direction of the positional deviation at the conveyance position defined at the desired conveyance location. (4th step).

In order to obtain an error vector at another transfer position from this error vector, the turning movement amount and the error expansion / contraction movement amount are calculated for each transfer according to the structure of the substrate transfer robot and the cause of the positional deviation. The converted error swing movement amount indicating the two components of the error vector at the position and the converted error expansion / contraction movement amount are converted (fifth step), and the values are converted into the stored rotation movement amount and the stored expansion / contraction movement. By adding each to the amount, the stored content indicating each transfer position is corrected (sixth step), and if the substrate is transferred based on the corrected turning movement amount and expansion / contraction movement amount, the substrate is placed at the correct transfer location. Will be able to.

When each of the transfer locations is individually evacuated, it is possible to select a transfer location in the chamber that does not require a high-quality vacuum state at the desired transfer location during the correction. It is not necessary to expose the transportation place of to the atmosphere.

Further, if a sensor for detecting the reference point is provided at the carrying position, it is not necessary to visually recognize the substrate holding portion even when re-teaching at a desired carrying place. Will not be exposed to the atmosphere.

[0021]

Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, 2 is an example of a substrate transfer robot that can be used in the present invention, and has a robot body 11 and an arm 1.

Inside the robot body 11, an inner shaft 4 ₁ and an outer shaft 4 ₂ having a coaxial structure are provided, and one rotation axis 3
It is configured so that they can rotate independently of each other. Arms 6 ₁ and 6 ₂ having the same length are attached to the inner shaft 4 ₁ and the outer shaft 4 ₂ , respectively, and one ends of the link members 7 ₁ and 7 _{2 having} the same length are swingably movable. It is attached to the arms 6 ₁ and 6 _{2 and} has a frog leg arm structure. The other ends of the link members 7 ₁ and 7 ₂ are attached to a mounting plate 9 of the substrate holding portion 10 with a space therebetween, and the arms 6 ₁ and 6 ₂ and the link members 7 ₁ and 7 ₂ and the substrate holding portion 10 constitute a link mechanism of section 5. Therefore, when the inner shaft 4 ₁ and the outer shaft 4 ₂ rotate in the same direction by the same amount to operate the link mechanism of the 5th node, the substrate holding unit 10 moves together with the arms 6 ₁ , 6 _2. When the inner shaft 4 ₁ and the outer shaft 4 ₂ rotate in the opposite directions by the same amount and the link mechanism of the five-node is operated, the rotation amount in the opposite direction is increased. The arm part 1 expands and contracts, and the substrate holding part 10 attached thereto also expands and contracts.

Motors 5 ₁ and 5 ₂ are attached to the inner shaft 4 ₁ and the outer shaft 4 ₂ , respectively. As shown in FIG. 2, the motors 5 ₁ and 5 ₂ and the motor 5 ₁ are attached. form part of a control system for controlling the five _second rotation amount, the transfer chamber 103
_1, 103 ₂ and the controllers 21 placed outside, by a cable 20 _second cable 20 ₁ and the signal system of the power system, transfer chamber 103 ₁ arranged in the substrate conveying robot 2, 10
_They are electrically connected to each other without breaking the vacuum in 32.

A magnetic sensor (not shown) is arranged in the robot body 11, and the substrate transfer robot 2
Is a home-return operation in which the state of the arm 1 when the magnets attached to the inner shaft 4 ₁ and the outer shaft 4 ₂ enter the detection range of the magnetic sensor is set to the home-return state. It can be done.

A pulse signal for independently rotating the inner shaft 4 ₁ and the outer shaft 4 ₂ is input to the motors 5 ₁ and 5 ₂ from the controller 21 via the cable 20 _2. The pulse signal corresponding to the inner shaft 4 ₁ is _one of the pulse signals.
Once were entered inner shaft 4 ₁ 1/64 degrees (deg) rotated, the outer shaft 4 when the pulse corresponding to ₂ is one input outer shaft 4 ₂ 1/64 degrees (deg) It is set to rotate.
Further, since the controller 21 has a counter for counting the number of pulses for rotating each of the inner shaft 4 ₁ and the outer shaft 4 ₂ , referring to the contents of the counter, the inner shaft 4 1 _The amount of rotation between ₁ and the outer shaft 4 ₂ can be obtained.

The controller 21 includes a cable 20.
The ₃ is connected to a sequencer 22 that instructs the order in which the substrate is transferred to the conveying locations, also by a cable 20 ₄ is connected to the teaching box 23 for performing the teaching operation of the substrate transport robot 2 There is.

The substrate transfer robot 2 includes the transfer chambers 103 ₁ and 10 3 of the semiconductor manufacturing apparatus 100 shown in FIG.
_No. 3 ₂ is arranged, and here, a control method of the one arranged in the transfer chamber 103 ₁ will be described.

Firstly, prior to the actual transport work, the cassette chamber 101 _1, the processing chamber 101 _2, 101 _3, with the intermediate chamber 101 within _4, the position of the transfer location to the wafer is a substrate respectively placed Teaching to memorize.

When a wafer is placed at each transfer location,
The points at which the wafer center should be located are points P ₁ , P ₂ ,
And P _3, P _4, with reference to FIG. 4, for determining the state of the first reference, the wafer transfer robot 2 is homing operation, the arm portion 1 to the homing state 31. And
The teaching box 2 while visually recognizing the wafer held by the pickup 8 of the substrate holding unit 10.
3 is operated, and the arm 1 is appropriately swung, expanded and contracted,
The arm portion 1 is brought into a transport end state 32 in which the wafer center is located on the point P ₁ .

From the origin return state 31 to the conveyance end state 3
The operation of the arm portion 1 up to 2 is the same as in the origin return state 31.
The arm ₆₁ and the arm 6 ₂ is rotated by turning angle omega ₁ in the same direction becomes a turning state 33, then the arm 6 _and 62 are rotated by an angle alpha ₁ extending in opposite directions from It can be considered that the arm portion 1 is extended to reach the transport end state 32.

Generally, only one combination (ω _n , α _n ) of the turning angle ω _n and the extension angle α _n is determined for each point P _n , and if the value is stored, the origin return state is used as a reference. The position of the point P _n can be saved.

Incidentally, the inner shaft 4 ₁ and the outer shaft 4 ₂ are each 1/64 degrees (d
Since the turning angle ω _n is 64 times the turning angle ω _n , the turning pulse number R _n (R
_n = 64 × ω _n ), which can be expressed by an integer pulse number, and the extension angle α _n is also an integer as the extension pulse number E _n (E _n = 64 × α _n ) that is 64 times the extension angle α _n. Since the position of the point P ₁ can be represented by the number of pulses, the value of the number of turning pulses R ₁ is the stored amount of swing movement, and the value of the number of extension pulses E _{1 is} the amount of stored extension / contraction movement, P ₁ (R ₁ , Remember E ₁ ).

As for the remaining points P ₂ , P ₃ and P ₄ , the wafer is tentatively moved and the rotation angles ω ₂ , ω ₃ and ω ₄ and the extension angles corresponding to the respective transfer locations are set similarly to the point P _1. α _2, α _3, α ₄ seek and to the pivot pulse number R _n with the value to 64 times the storage memory pivotal movement amount, the elongation number of pulses E _n as storage expansion movement amount, P ₂ (R _2, E ₂ ), P ₃ (R ₃ ,
The position of each point P _n is memorized by E ₃ ), P ₄ (R ₄ , E ₄ ), and the teaching work is completed.

During the teaching work, the arm 6 ₁ when the arm 1 is in the origin return state 31 is used.
The angle between the arm 6 ₂ and the arm 6 ₂ is obtained. An angle θ _{0 that} is ½ of that angle is called an opening angle, and this opening angle θ ₀ is also the number of opening pulses G ₀ (G ₀ = 64) that is 64 times that value.
It is stored as xθ ₀ ).

By the way, the turning amount of the arm portion 1 is an angle and is directly represented by the turning angle ω _n, but the extending and contracting amount of the arm portion 1 is a distance and the extension angle α _n.
Is not directly represented by.

[0036] This is explained with reference to FIG. 5 (a) the relationship between the deformation amount and the turning angle of the arm portion 1, the link member _71,
The positions where 7 ₂ is attached to the attachment plate 9 are points Q ₁ and Q ₂ , respectively, and the midpoint of the line segment connecting the points Q ₁ and Q ₂ is the reference point on the substrate holder 10. Let Q ₀ . Moreover, when the arm portion 1 is in the origin return state 31, a straight line passing through the reference point Q ₀ and intersecting the rotation axis 3 at a right angle is 40.
In the return-to-origin state 31, the straight line 40
And the arms 6 ₁ and 6 ₂ respectively have the opening angle θ _0.
It is assumed that they are communicating with each other.

Such a straight line 40 and the arms 6 ₁ , 6 ₂
The angle at which and intersect is generally called the “expansion / contraction angle”, and the opening angle θ ₀ indicates the value of this expansion / contraction angle in the return-to-origin state. Also, the reference point Q
The distance between ₀ and the axis of rotation 3 is called the "expansion / contraction distance", and the arm 1 is in the home-return state 31.
The value of the expansion / contraction distance when the value of the expansion / contraction angle is θ ₀ is set to L ₀ . Reference numeral 24 in FIG. 5 (a) shows an extended state of the arm portion 1.
_{When 1} and 6 ₂ are rotated in opposite directions by the expansion / contraction angle θ and the value of the expansion / contraction distance is L, the expansion / contraction distance L is
The link members 7 _1, 7 ₂ of the length a constant s ₁ The arms 1, the arms ₆₁ and 62 constant s _{2 2} of length, and the point Q ₀ and the point Q _1, Q ₂ The distance is a constant s ₃ and the expansion / contraction angle θ is a variable, which is represented by a function f (θ) of the following equation (1). Note that √ (A) represents the square of A.

L = f (θ) = √ [s ₁ ² − {s ₂ · sin (θ) −s ₃ } ² ] −s ₂ · cos (θ) (1)

In the equation (4) described later, a = s ₁ ² -s ₂ ² -s ₃ ² -L ² (2) b = 2 · s ₂ · √ (L ² + s ₃ ² ) (3), the expansion / contraction angle θ has the expansion / contraction distance L as a variable, and is a function h of the following equation having an inverse function relationship with f (θ).
It is represented by (L). θ = h (L) = sin ^-1 (-a / b) + cos ^-1 (s ₃ / √ (L ² + s ₃ ² )) (4)

Here, s ₁ = 260 mm, s ₂ = 245
FIG. 5 is a graph of the function f (θ) when mm and s ₃ = 20 mm.
It shows in (b). Although the slope dL / dθ varies depending on the size of the expansion / contraction angle θ, it can be seen that when the expansion / contraction angle θ is determined, only one expansion / contraction distance L is determined.

However, when the maintenance work is performed and the arms 6 ₁ and 6 ₂ of the arm ₁ and the link members 7 ₁ and 7 ₂ are exchanged (hereinafter, abbreviated as arm exchange), the substrate transfer robot 2 Even if the arm 1 is returned to the origin by performing the origin return operation, the origin return state before replacement and the origin return state after replacement do not match.

This state is shown in FIG. 6 (a). Reference numeral 34 denotes a return-to-origin state after the arm replacement. When the midpoint between the two attachment positions of the link members 7 ₁ and 7 ₂ after the arm replacement is the reference point Q ₀ ′, the reference point Q ₀ before the arm replacement is shown. The position of and the position of the reference point Q ₀ ′ after the arm replacement do not coincide with each other, and a position shift is generated. Here, the opening angle θ ₀ before the arm replacement changes to θ ₀ ′ after the arm replacement, and the straight line 40 before the arm replacement rotates by Δω,
It is assumed that a straight line 41 is formed after the arms are replaced. Such misalignment also affects the movement of the wafer to the transfer location, and thus needs to be corrected.

The procedure of one embodiment of the present invention for correcting this positional deviation will be described. First, a desired carrying place is selected from the carrying places. Here, it is assumed that the cassette room 101 ₁ is selected.

Next, using the teaching box 23, the substrate holding unit 10 is visually moved into the cassette chamber 101 ₁ , and the wafer center placed on the pickup 8 is moved to the point P ₁ (wafer center is (Point to be located)
Then, the teaching room at the cassette chamber 101 ₁ is re-teached. Here, before the arm exchange, when the wafer center placed on the pickup 8 is placed on this point P ₁ , the reference point Q ₀ before the arm exchange is at the transfer position P ₁ ′ near the point P _1. It is assumed that the wafer is positioned, and the positional deviation due to the arm replacement is a change in the opening angle of the arm and the orientation in the initial state. Even after the positional deviation due to the arm replacement occurs, the wafer center placed on the pickup 8 is Point P
_It is assumed that the reference point Q ₀ ′ after the arm replacement is located at the transfer position P ₁ ′ when placed at ₁ . in this case,
The reference point on the substrate holding unit 10 is the reference point Q ₀ ′, and the corresponding transport position is the transport position P ₁ ′.

When the number of turning pulses when this re-teaching is performed is R ₁ ′ and the number of extension pulses is E ₁ ′, a correction that correctly indicates the transport position P ₁ ′ with reference to the return-to-origin state 34 after replacement. The value of the turning movement amount and the value of the corrected expansion / contraction movement amount are R ₁ 'and E ₁ ', respectively. The turning angle at this time was ω ₁ 'and the extension angle was α ₁ '.

Of the memory swivel movement amount R ₁ and the memory expansion / contraction movement amount E ₁ corresponding to the cassette chamber 101 ₁ , and the corrected swivel movement amount R ₁ 'and the corrected expansion / contraction movement amount E ₁ ' after the arm replacement. The respective differences are calculated, and the error turning movement amount ΔR _a1 and the error expansion / contraction movement amount ΔE are calculated by the following equations: ΔR _a1 = R ₁ ′ −R ₁ (6) ΔE _a1 = E ₁ ′ −E ₁ (7) We ask for _a1 .

By the way, the opening angle θ ₀ before the arm replacement is
(4) Using the formula, θ ₀ = expressed as _{h (L c) -E 1/} 64 ...... (10). The opening angle θ ₀ before the arm replacement indicates the distance between the center of the wafer held by the pickup holding unit 8 and the rotation axis 3 in the return-to-origin state. And
Since the arm portion 1 further extends from the distance in the return-to-origin state by the extension pulse number E ₁ , and the wafer center is placed at the point P ₁ in the cassette chamber 101 ₁ , the rotation axis 3 Assuming that the distance from the point P ₁ is L _c , the number of opening pulses G ₀ obtained by converting the opening angle θ ₀ into the number of pulses is G ₀ = 64 · θ ₀ = 64 · h (L _c ) −E ₁ ... … (11) can be calculated backward.

On the other hand, the opening angle in the return-to-origin state 34 after the arm replacement is θ ₀ ', and the number of extension pulses when the arm is forcibly extended from this state and the wafer is transferred is E ₁ Therefore, the number of opening pulses G ₀ 'corresponding to the opening angle θ ₀ ' is inversely calculated as G ₀ '= 64h (L _c ) -E ₁ ' ... (12) as in the above equation. can do.

When the above equation (7) is rewritten using the above equations (11) and (12), the error expansion / contraction movement amount ΔE _a1 which is the difference between the extension angle before replacement and the extension angle after replacement is ΔE and _{a1 = E 1 -E 1 '=} -G 0 + G 0' ...... (15), may also be represented by the difference between the number of open angle pulses. Figure 6
In (b), the error expansion / contraction movement amount ΔE _a1 is shown in a graph of the expansion / contraction angle θ and the expansion / contraction distance L.

In the case where such a change in the return-to-origin state occurs due to the exchange of the arm and a positional deviation at the transfer place occurs accordingly, the error turning movement amount ΔR indicating the positional deviation in the cassette chamber 101 ₁ . _a1 and the error expansion / contraction movement amount ΔE _a1 are converted error rotation movement amounts ΔR _an and conversion error expansion / contraction movement amounts ΔE indicating the positional deviations at the respective conveyance locations.
_When converting to _an , the following equation holds for all n. ΔR _an = ΔR _a1 , ΔE _an = ΔE _a1 (16)

Therefore, ΔR _a1 and ΔE _a1 are respectively added to the stored turning movement amount indicating each transfer location and the stored expansion / contraction movement amount before the displacement due to the arm exchange occurs, and the storage position indicating each transfer location is stored. The content is (R ₁ , E ₁ ) → P ₁ (R ₁ + ΔR _a1 , E ₁ + ΔE _a1 ) (R ₂ , E ₂ ) → P ₂ (R ₂ + ΔR _a1 , E ₂ + ΔE _a1 ) (R ₃ , E ₃ ) → P ₃ (R ₃ + ΔR _a1 , E ₃ + ΔE _a1 ) (R ₄ , E ₄ ) → P ₄ (R ₄ + ΔR _a1 , E ₄ + ΔE _a1 ) Correctly conveys.

By the way, the return-to-origin state of the arm 1 also changes when the pickup 8 is replaced. An embodiment of the present invention for correcting the positional deviation caused by the exchange of the pickup will be described.

FIG. 6 (c) is a schematic view showing a state in which the displacement has occurred due to the exchange of the pickup, and the wafer center when the wafer is placed on the pickup is at the position indicated by point U ₀ before the exchange. However, when the pickup 8 is replaced, it is assumed that the pickup 8 has moved to the position indicated by the point U ₀ '. When the center of the wafer moves and the return-to-origin state changes in this way, when the wafer is conveyed as taught, it becomes impossible to place the wafer in the correct place.

The procedure of the embodiment of the present invention for correcting this displacement will be described. Also in this embodiment, as in the above-described embodiments, the semiconductor manufacturing apparatus 100 and the substrate transfer robot 2 are used, and when the wafer is correctly placed at each transfer location, the wafer center is located at the point P _n . It is assumed that the memory swing movement amount and the memory expansion / contraction movement amount indicating the position of each transfer location are P ₁ (R ₁ , E ₁ ), P ₂ as a combination of the swing pulse number R _n and the extension pulse number E _n. (R ₂ , E ₂ ), P ₃ (R ₃ ,
E ₃ ) and P ₄ (R ₄ , E ₄ ) are stored.

With respect to the positional deviation caused by the exchange of the pickup, the reference point defined on the substrate holding portion is the point U ₀ 'at the center of the wafer held by the pickup 8 after the exchange, and each transfer is performed. When the cassette room 101 ₁ is selected from among the locations, the transfer position determined corresponding to the reference point U ₀ 'is the point P ₁ .

Referring to FIG. 7, after replacing the pickup 8,
Using the teaching box 23, the substrate holding unit 10 is moved into the cassette chamber 101 ₁ while visually observing the reference point U ₀ ′ on the transfer position P ₁ . When the value of the number of turning pulses at that time is R ₁ ″ and the value of the number of extending pulses is E ₁ ″, the value of the corrected turning movement amount and the corrective expansion / contraction movement that correctly indicate the transfer position P ₁ after the pickup replacement. The quantity values are R ₁ ″ and E ₁ ″, respectively.

On the other hand, when the arm 1 is moved in accordance with the stored turning movement amount R ₁ and the stored expansion and contraction movement amount E ₁ corresponding to the carrying position P ₁ , the reference point U ₀ ′ is the correct carrying position. It is assumed to be located at a point T ₁ that is displaced from P ₁ .

The error turning movement amount ΔR _b1 and the error expansion / contraction movement amount ΔE _{b1 at the} transport position P ₁ are (R ₁ , E ₁ ),
(R ₁ ″, E ₁ ″), ΔR _b1 = R ₁ ″ −R ₁ (21) ΔE _b1 = E ₁ ″ −E ₁ (22)

If a straight line passing through the point T ₁ and intersecting the rotation axis 3 at a right angle is a straight line 50 and an intersection with the rotation axis 3 is a point O, the error turning movement amount ΔR
_b1 is an angle ∠P ₁ OT ₁ formed by the straight line 50 and the straight line P ₁ O
Therefore, ΔR _b1 = 64 · ∠P ₁ OT ₁ = 64 · δ ₁ (23) (where, δ ₁ = ∠P ₁ OT ₁ ).

In the case other than the cassette chamber 101 ₁ , the reference point U ₀ ′ is located at a position different from the point P _n when moved according to the memory swing movement amount R _n and the memory expansion / contraction movement amount E _n indicating each transfer place. Assuming that the point is located at the shifted point T _n , the error turning movement amount ΔR _bn and the error expansion / contraction movement amount ΔE at each transfer location.
_bn is the same as ΔR _b1 and ΔE _b1 described above, ΔR _bn = R _n ″ −R _n = 64 · δ _n (24) (where δ _n = ∠P _n OT _n ) ΔE _bn = E _n it can be expressed by "-E _n ...... (25).

Here, if a point J ₁ that satisfies OP ₁ = OJ ₁ (27) is given on the straight line 50, OP ₁ -OT ₁ = OJ ₁ -OT ₁ = T ₁ J ₁ ... ( 28) Therefore, if L ₁ = OT ₁ , ΔL ₁ = T ₁ J ₁ (29) is set, the error expansion / contraction movement amount ΔE _b1 can be calculated by using the equation (4), ΔE _b1 = 64 · h _{(OJ 1) -64 · h (} OT 1) = 64 · h (L 1 + ΔL 1) -64 · h (L 1) = 64 · h (L 1 + ΔL 1) - (G 0 + E 1) ...... ( 30)

[0062] Further, similarly to the point J _1, on the line OT _n connecting said point T _n and the point O, giving _{OP n = OJ n ...... (31} ) to become a point J _n, L _n = OT _n, putting the _{ΔL n = T n J n ......} (32), said Delta] E _{bn is, ΔE bn = 64 · h (} OJ n) -64 · h (OT n) = 64 · h (L n + ΔL _n )-(G ₀ + E _n ) ... (33)

Here, the point T _n is an erroneous conveyance place, an error vector C _n connecting the correct point P _n and the point T _n is considered, and an angle formed by the error vector C _n and the straight line OJ _n is considered. ∠
_Let P _n T _n J _n be an error angle ξ _n (∠P _n T _n J _n = ξ _n ), and _let the length of the error vector C _n be represented by | C _n |
In the isosceles triangle P _n OJ _n , the following equation holds. tan (δ _n ) = | C _n | · sin (ξ _n ) / {L _n + | C _n | · cos (ξ _n )} ... (34)

Further, due to the structure of the substrate transfer robot 2 and the characteristic of the positional deviation caused by the exchange of the pickup, the error vector C _{n at} the point P _{n at} each transfer location has the magnitude | C _n | Since the value of the angle ξ _n is the same at all the transfer locations, the following two expressions are established. │C _n │ = │C ₁ │ (35) ξ _n = ξ ₁ ...... (36)

Here, the triangle P _n OJ _n and the triangle P ₁
Focusing on OJ ₁ , the following two equations: | C _n | · sin (ξ _n ) = (L _n + ΔL _n ) · sin (δ _n ) = (L ₁ + ΔL ₁ ) · sin (δ ₁ ) ... (37) | C _n | · cos (ξ _n ) = (L _n + ΔL _n ) · cos (δ _n ) −L _n = (L ₁ + ΔL ₁ ) · cos (δ ₁ ) −L ₁ (38) And the angle δ is calculated from the equation (23).
_{Since 1} can be expressed as δ ₁ = ΔR _b1 / 64 (39), the error turning movement amount ΔR _bn can be _calculated from the above (3).
4), (37), (38), and (39), the following equation

[Equation 1] Can be represented by

Further, the following two equations, Δθ _n = h (L _n + ΔL _n ) -h (L _n ) ... (45) (L _n + ΔL _n ) .sin (δ _n ) = (L ₁ + ΔL ₁ )・ Sin (δ ₁ ) ... Rewriting the above equation (33) by (46), the error expansion / contraction movement amount ΔE _{bn at} each transfer place is calculated by the following equation:

[Equation 2] Can be represented by

In the equation (30), the cassette chamber 1
The error turning movement amount ΔR _b1 and the expansion and contraction movement amount ΔE _{b1 at} 01 ₁ (conveyance position P ₁ ) can be directly obtained by the equations (21) and (22), and E ₁ , G ₀ and L ₁ The value is known. Furthermore, the value of [Delta] L _1, the (30) rewrite the equation, the following equation can be calculated from _{ΔL 1 = f {(G 0} + E 1 + ΔE b1) / 64} -L 1 ...... (48), the When the value is substituted into the equation (40), can be calculated the value of the error pivotal movement amount [Delta] R _bn in all transport location, further, the thus the value to the value of the [Delta] L ₁ of [Delta] R _bn obtained above (47 Substituting into the equation), the error expansion / contraction movement amount ΔE _{bn at} all the transfer locations is obtained.

As a result of the above results, the memory turning movement amount and the memory expansion / contraction movement amount indicating the respective transportation locations are corrected as follows. (R ₁ , E ₁ ) → P ₁ (R ₁ + ΔR _b1 , E ₁ + ΔE _b1 ) (R ₂ , E ₂ ) → P ₂ (R ₂ + ΔR _b2 , E ₂ + ΔE _b2 ) (R ₃ , E ₃ ) → P ₃ (R ₃ + ΔR _b3 , E ₃ + ΔE _b3 ) (R ₄ , E ₄ ) → P ₄ (R ₄ + ΔR _b4 , E ₄ + ΔE _b4 )

As described above, if the transfer position is determined at one transfer location and the re-teaching is performed, the positional deviation can be corrected without performing the re-teaching at the other transfer positions, so that the time required for the re-teaching can be shortened.

When correcting the positional deviation, it is not necessary to open the chamber in which another transfer place is located. Therefore, it is not necessary to open the vacuum chamber or the reactor chamber to expose it to the atmosphere. It is possible to significantly reduce the time required to recover to the performance of.

As still another embodiment of the present invention, there is a case where the arm displacement and the pickup exchange are simultaneously performed to correct the positional deviation. In this case, the displacement of the arm is first corrected by the reference point Q ₀ ′ after the arm exchange and the transport position P ₁ ′ corresponding to the reference point Q ₀ ′, and then the reference point U. 'and, the reference point U _{0' 0} if correction of positional deviation of the pick-up exchange and the transport position P ₁ corresponding to the contents stored indicating each conveying locations is modified as follows. (R ₁ , E ₁ ) → P ₁ (R ₁ + ΔR _a1 + ΔR _b1 , E ₁ + ΔE _a1 + ΔE _b1 ) (R ₂ , E ₂ ) → P ₂ (R ₂ + ΔR _a1 + ΔR _b2 , E ₂ + ΔE _a1 + ΔE _b2 ) (R ₃ , E ₃ ) → P ₃ (R ₃ + ΔR _a1 + ΔR _b3 , E ₃ + ΔE _a1 + ΔE _b3 ) (R ₄ , E ₄ ) → P ₄ (R ₄ + ΔR _a1 + ΔR _b4 , E ₄ + ΔE _a1 + ΔE _b4 ).

In this way, the working time when the positional deviation is corrected according to the present invention is compared with the working time when the positional deviation is corrected by re-teaching of all rooms of the prior art, and the following table is given. It is described in 1. According to the present invention, the total working time in the past was 11 hours and 50 minutes, but was shortened to 3 hours and 50 minutes.

[Table 1]

Although the substrate transfer robot 2 having the link mechanism described in Section 5 has been described above, the present invention is not limited thereto. For example, as shown in FIG. 8, the present invention can also be applied to a substrate transfer robot having arm portions 1 ′ configured so that _two rotation axes can independently rotate about different rotation axis lines 3 ₁ and 3 _2. You can

Considering a virtual arm by connecting the rotation axes 3 ₁ and 3 ₂ , this arm portion 1 ′ has a link mechanism of 6 joints. The same parts as those of the substrate transfer robot 2 having the link mechanism described in Section 5 are designated by the same reference numerals, and a method of controlling this substrate transfer robot will be described. However, in the return-to-origin state, the reference point Q ₀ and the two rotation axis lines 3 ₁ ,
A straight line connecting the midpoint of 3 ₂ is defined as a straight line 40 ′, and the opening angle θ ₀ of this substrate transfer robot is set to the straight lines 40 ′ and the arms 6 ₁ and 6 _{2 of the} arm portion 1 ′ in the origin returning state. The angle at which and intersect.

Further, as in the case of the substrate transfer robot 2 having the link mechanism described in Section 5, the lengths of the link members 7 ₁ and 7 ₂ are constant s ₁ , and the lengths of the arms 6 ₁ and 6 ₂ are constant s _2. , The distance between the reference point Q ₀ and the points Q ₁ and Q ₂ is a constant s ₃ , and further, the rotation axis 3 ₁ and the rotation axis 3 ₂ and the straight line 4
The distance from 0 ′ is a constant s _4, and s ₅ = s ₃ −s ₄ (50) is set, and the relationship between the distance L and the expansion / contraction angle θ is calculated in the same manner as in the above formula (1). It is expressed by the function g (θ) of the equation. L = g (θ) = √ [s ₁ ² − {s ₂ · sin (θ) −s ₅ } ² ] −s ₂ · cos (θ) (51)

Further, if c = s ₁ ² −s ₂ ² −s ₅ ² −L ² (52) d = 2 · s ₂ · √ (L ² + s ₅ ² ) (53), then Similar to the function h (L), the expansion / contraction angle θ is
It is represented by the following function j (L), which is an inverse function of g (θ). θ = j (L) = sin -1 (-c / d) + cos -1 (s 5 / √ (L 2 + s 5 2)) ...... (54)

Then, instead of the function f (θ), the g
(θ), the function h (L) is replaced by the function j (L), and when the carrying position is determined in the same manner as in the above-described embodiments, the cassette chamber 101 ₁ is selected and re-teaching is performed. ,
Since the error turning movement amounts ΔR _a1 and ΔR _{b 1} and the error expansion / contraction movement amounts ΔE _a1 and ΔE _b1 are obtained, the converted error rotation movement amount and the converted error expansion / contraction movement amount at another conveyance place are calculated as follows. Similar to the above-described embodiment, it can be calculated based on the cause of the positional deviation based on the operation of the link mechanism in the section 6.

As described above, the present invention can be widely applied to a substrate transfer robot provided with a link mechanism that performs a turning movement and a telescopic movement by the rotation of two rotating shafts.

Although the above embodiment has been described by taking as an example a semiconductor manufacturing apparatus having four transportation places, the number of transportation places is not limited thereto. Further, although the cassette chamber 101 ₁ is selected from a plurality of chambers and re-teaching is performed, the transfer place for performing the re-teaching is not limited to the cassette chamber 101 ₁ and recovery is possible even when exposed to the atmosphere. Any chamber can be used as long as it is an easy chamber, and even if re-teaching is performed not at one place but at a plurality of places, it is only necessary to open a chamber that is not exposed to the atmosphere.

Further, in particular, in order to correct the positional deviation by exchanging the arm, a reference transfer position P ₀ is set in advance in a vacuum atmosphere in a place different from the chamber used for wafer processing in the semiconductor manufacturing apparatus. Oite, when performing teaching of the conveying locations, the reference point Q _0, is tentatively moved on the conveying position P ₀ as the this reference, it causes also stores the position of the transport position P _0, the transport position P ₀ The distance between the rotation axis 3 and the rotation axis 3 is obtained, and when a displacement occurs due to the arm exchange, the reference point Q ₀ ′ of the substrate holder 10 after the exchange is forcibly moved to the transfer position P _0. If the positional deviation is corrected in the same manner as in the first embodiment described above, it is not necessary to expose all the chambers to the atmosphere.

Further, if a sensor is provided at the reference transport position P ₀ and the reference points Q ₀ and Q ₀ ′ are detected electrically and magnetically, it is not necessary to visually recognize them. The transfer chamber in which the substrate transfer robot is arranged can also be corrected for misalignment without being exposed to the atmosphere, and the working time can be further shortened.

In the above embodiment, the case where the displacement of the arm or the pickup occurs due to the displacement has been described. However, the present invention is not limited to this. It also includes correcting the deviation. Further, the present invention is not limited to controlling the substrate transfer robot arranged in the vacuum device, but can be widely applied to the substrate transfer robot arranged in a device having a chamber which is inconvenient when exposed to the atmosphere.

Although the number of pulses is stored in the above embodiment, it is needless to say that the number of pulses is not limited to this.

[0084]

According to the present invention, when the positions of a plurality of transfer locations stored by teaching are corrected, it is sufficient to re-teach at least one location, and the time required for re-teaching is reduced.

Furthermore, since it is not necessary to open a chamber which is not easily restored to its original state when exposed to the atmosphere, the working time can be greatly reduced, and the substrate transfer robot is arranged. The work time can be further shortened if the vacuum atmosphere is not broken.

[Brief description of drawings]

FIG. 1 is an example of a substrate transfer robot having a 5-section link mechanism to which the present invention can be applied.

[Figure 2] Block diagram of the robot

FIG. 3 is an example of a semiconductor manufacturing apparatus in which the substrate transfer robot is used.

FIG. 4 is a diagram for explaining teaching work.

5A is a diagram for explaining expansion and contraction movement. FIG. 5B is a graph showing a relationship between expansion and contraction angle θ and elongation L.

FIG. 6A is a diagram showing a return-to-origin state changed by exchanging the arm. FIG. 6B is a graph for explaining a reference point changed by exchanging the arm. FIG. 6C is a diagram showing a return-to-origin state changed by exchanging the pickup.

FIG. 7 is a diagram for explaining the size and direction of each positional displacement amount caused by the exchange of the pickup.

FIG. 8 is an example of a substrate transfer robot having a 6-section link mechanism to which the present invention can be applied.

[Explanation of symbols]

1, 1 '... Arm 2 ... Substrate transfer robot 3 ...
… Rotation axis 4 ₁ 4 ₂ …… Two rotation axes 11 …… Robot body 10 …… Substrate holder 31, 34 …… Returning the arm to the origin Q ₀ ′, U ₀ …… Reference point P ₁ ′ , P ₁ , P ₀ ...... Conveying position R _n ...... Rotation movement amount E _n ...... Expansion / contraction movement amount R ₁ , R ₂ , R ₃ , R ₄ ...... Memory rotation movement amount E ₁ , E ₂ , E ₃ , E ₄ …… Memory expansion / contraction movement amount R ₁ ′, R ₁ ″ …… Corrected turning movement amount E ₁ ′, E ₁ ″ ……
Corrected expansion / contraction movement amount ΔR _a1 , ΔR _b1 , ... Error turning movement amount ΔE _a1 , ΔE
_b1・ ・_・ Error expansion / contraction movement amount ΔR _a1 , ΔR _b2 , ΔR _b3 , ΔR _b4 …… Conversion error turning movement amount ΔE _a1 , ΔE _b2 , ΔE _b3 , ΔE _b4 …… Conversion error expansion / contraction movement amount G ₀ …… Number of opening pulses L: Stretch distance θ: Stretch angle θ _0: Open angle α: Stretch angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G05B 19/18 H01L 21/68 A G05B 19/18 D

Claims (3)

[Claims] 1. A robot main body having two rotating shafts, and a link mechanism attached to the two rotating shafts, which is rotated by rotation of the two rotating shafts in the same direction and expands and contracts by rotating in the opposite direction. An arm part, a substrate holding part provided on the arm part and forming a part of the link mechanism, and a substrate held by the substrate holding part are transferred to a plurality of transfer locations arranged around the robot body. A robot control method for controlling a substrate transfer robot, wherein, based on a return-to-origin state of the arm portion, a swung amount of the arm portion is set as a swivel movement amount, and a stretched amount is set as a stretchable movement amount. Is temporarily moved to each of the transfer locations, and the turning movement amount and the expansion / contraction movement amount at that time are stored as a memory turning movement amount and a storage expansion / contraction movement amount indicating the position of each transfer location, and the substrate transfer robot , The memory According to the contents, in the robot control method of actually transferring the wafer to each transfer location, in the case where the origin return state of the substrate holding unit changes and the wafer is transferred according to the stored contents, a positional deviation occurs, and the following steps are performed. A robot control method characterized in that the positional deviation is corrected in a positional deviation correcting step including the step. (1) A first step in which a reference point is set on the substrate holder according to the cause of the positional deviation and a transfer position corresponding to the reference point is set on a desired transfer location selected from the plurality of transfer locations. (2) A second step of forcibly moving the substrate holder so that the reference point is located on the transfer position. (3) A third step of obtaining the turning movement amount and the extension / contraction movement amount when the forced movement is performed and setting the corrected turning movement amount and the correction extension / contraction movement amount that correctly indicate the transport position. (4) From the difference between the values of the stored turning movement amount and the stored extension / contraction movement amount corresponding to the desired conveyance location, and the values of the corrected turning movement amount and the corrected extension / contraction movement amount, the positional deviation at the conveyance position is calculated. A fourth step of calculating the error turning movement amount and the error expansion / contraction movement amount shown. (5) Converting the error rotation movement amount and the error expansion / contraction movement amount obtained in the fourth step into values corresponding to each conveyance position according to the cause of the position deviation, and showing the position deviation at each conveyance position. A fifth step of obtaining the error turning movement amount and the conversion error expansion / contraction movement amount. (6) The converted error swing movement amount and the converted error expansion / contraction movement amount obtained in the fifth step are respectively added to the stored rotation movement amount and the stored expansion / contraction movement amount corresponding to each of the transport positions,
A sixth step of correcting the stored content indicating each transport position. 2. Each of the transfer locations is individually evacuated, and a transfer location that does not require a high-quality vacuum state is selected for the desired transfer location and another transfer location is used when correcting the positional deviation. The robot control method according to claim 1, wherein the robot is not exposed to the atmosphere. 3. The robot control method according to claim 1, wherein a sensor for detecting the reference point is provided at the carrying position, and the positional deviation is corrected without exposing each carrying place to the atmosphere.