JP2004172287A - Wafer carrier, inspecting wafer and method for regulating wafer insertion to wafer carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a positional deviation occurs when a wafer is inserted into a wafer carrier owing to the deformation of the wafer carrier used to house and convey a plurality of Si wafers for a long period in a processing work in a clean room, the mechanical wear of a bearing built in a conveying arm, loosening of a mounting screw, etc., and the wafer is rubbed with the wafer carrier to cause particles to be generated with the result that a processing yield is lowered. <P>SOLUTION: In order to easily regulate the conveying arm so as not to rub the wafer with the wafer carrier 4 when the wafer is inserted into a predetermined step in the periodic inspection of a wafer conveying system, the conveying arm is regulated by using an inspecting wafer, the peripheral edge of which is metallized so as to easily bring the wafer carrier 4 having electrodes 7-9 provided at a wafer introducing part into contact with the electrodes 7-9. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
In a semiconductor process, the present invention relates to a method of adjusting a transfer arm so that a wafer and a wafer carrier do not rub against each other when a wafer is inserted into a wafer carrier used for transferring a wafer.
[0002]
[Prior art]
In a semiconductor device manufacturing process, a wafer is transported in a wafer carrier in order to facilitate transportation and prevent particles floating in the air from adhering. FIG. 3 shows a state where the wafer 1 is mounted on the wafer carrier 4. However, when the wafer 1 is inserted into the wafer carrier 4, if both rub, the particles will be generated. In fact, particles generated due to friction between the wafer 1 and the wafer carrier 4 have become a problem as semiconductors become more highly integrated. In the future, as the diameter of the wafer 1 increases and its weight increases, it is important to manage the wafer 1 more strictly than before so that the wafer 1 is inserted into the wafer carrier 4 without rubbing.
[0003]
FIG. 4 is an enlarged view of a cross section of the wafer carrier and a peripheral portion of the wafer when a wafer is inserted into the wafer carrier at a certain stage in FIG. 3. The transfer arm stretches the arm, which has been processed by the exposure device or etching device, and secures it to the wafer holder by vacuum suction or dropping. Insert between the bars of the step. After the wafer is inserted, the wafer carrier is raised or the transfer arm is lowered, and the wafer is set on a crosspiece of the wafer carrier as shown in FIG.
[0004]
However, during use for a long period of time, deterioration of the bearing of the transfer arm, synchronization deviation of the synchronous motor, bending of the transfer arm, deformation of the wafer carrier, displacement of the position where the wafer carrier is set, and the like occur. Then, the wafer is inserted or ejected in a state where the wafer and the rail or the inner wall of the wafer carrier are in contact with each other. Furthermore, if the position for inserting the wafer is greatly shifted, the wafer will not enter the wafer carrier and will be broken. For example, a wafer carrier containing an 8-inch wafer for semiconductor manufacturing has a worst-case negative tolerance of ± 0.5 mm because the interval between the lower and upper bars is 1.9 mm, but the tolerance of the bars is ± 0.5 mm. In this case, when a wafer having a thickness of 0.72 mm is used, there is only a gap of only 0.34 mm at each of the upper and lower sides, and very high transfer accuracy is required.
[0005]
As a method of accurately inserting a wafer into a wafer carrier, a light reflection type photoelectric sensor using an optical fiber as a stage on which a wafer of a wafer transfer device is mounted as shown in JP-A-61-267622 or an electrostatic There is a method of using a non-contact type sensor such as a capacitive sensor to guide the stage into the storage groove. The purpose of this method is to insert the stage on which the wafer is mounted into the groove, and it is out of consideration that the wafer carrier and the stage are rubbed. Rather, adopting a universal connection structure that allows the stage to freely tilt with respect to the axis of the elevating mechanism so that the stage can be inserted along the groove, the groove and the stage are actively rubbed. Therefore, this method cannot transfer a wafer with a transfer accuracy of 0.34 mm.
[0006]
Even if the rubbing with the wafer carrier is on the back surface or side surface of the wafer, particles generated by the rubbing are wrapped around the surface of the wafer by a wet process or a plasma process, causing a reduction in yield.
[0007]
[Problems to be solved by the invention]
It is necessary to perform high-precision inspections and inspections so that the wafer carrier does not rub against the wafer carrier due to deformation and displacement of the wafer carrier due to aging and changes in the setting position of the transfer arm. Rather, there is a need for a method that can be adjusted automatically and electromechanically. An object of the present invention is to provide a method for positioning a transfer arm.
[0008]
[Means for Solving the Problems]
Using a wafer of the same size as the Si wafer used in the process, perform a predetermined operation on the transfer arm while monitoring the electrical connection of the metal electrode provided on the wafer carrier, the Si wafer, and the path of the transfer arm, Once the electrical connection is detected, the operation of the transfer arm is stopped. At this time, the position detected by the Si wafer and the wafer carrier is the upper surface on either the left or right of the predetermined beam, the lower surface on either the left or right of the upper beam of the predetermined beam, or the left or right of the wafer carrier housing. This means that at least one of the six positions on the side surface has come into contact. Based on this information, the transfer arm is moved in the opposite direction, the connection signal disappears, and the position where the connection signal is generated again and the connection signal is generated again is confirmed. By setting it as the completed position, adjustment in one direction is possible. Further, if the same operation is performed in the remaining two directions, the adjustment point of the transfer arm in three dimensions is obtained. Further, this operation is performed for each stage, and finally, the data of the adjustment point in each stage is stored for each wafer carrier. And finish the adjustment.
[0009]
The first invention relates to an electrode provided for determining contact when a wafer is inserted into each stage, and the upper surface of the right and left crosspieces of the stage to be inserted and the lower surface of the left and right crosspieces of the upper stage of the same. And a total of six checkpoints on the left and right inner surfaces of the wafer carrier housing holding the crosspiece.
Preferably, the metal electrode is provided from the wafer insertion opening of the wafer carrier to a position where the wafer is completely housed inside the wafer carrier, that is, a position longer than the radius of the wafer.
[0010]
By moving the wafer so as to come into contact with these six metal electrodes, the position of the wafer can be known.
According to the second invention, normally, the back surface and side surfaces of the Si wafer used in the process are untreated and covered with a natural oxide film, so that the silicon wafer does not conduct even if it comes into contact with the metal electrode as it is. Therefore, in order to electrically confirm that the wafer has come into contact, an ohmic metallized pattern is provided on the peripheral portion of the wafer where contact is expected and the wafer surface of the portion of the transfer arm that is in contact with the wafer holder, This is a wafer for inspection at the time of wafer insertion.
[0011]
By providing the metallized pattern, the resistive element can be regarded as a resistance element of a path reaching the metallized pattern at the peripheral portion via the wafer bulk crystal via the wafer holder. When the resistance element contacts the six metal electrodes, the electrodes are individually biased, so that a current flows and the presence or absence of the contact can be grasped as an electric signal.
[0012]
Preferably, the metallized pattern of the peripheral portion is a portion that may come into contact with the crosspiece or the inner wall, and is not provided on the entire circumference but is divided on the left and right.
The third invention is characterized in that the transfer position of the transfer arm is adjusted using the wafer carrier of the first invention and the inspection wafer of the second invention so that the wafer does not rub against the wafer carrier.
[0013]
Where the wafer is set in the three-dimensional space for each stage of the wafer carrier is quantified at the design stage. However, the deformation of the wafer carrier, the positional accuracy of the transfer arm, and the like change over time. In order to accurately detect such a change, it is necessary to perform three-dimensional dimension measurement and determine whether or not the measured value is within an allowable range. However, it is difficult to accurately obtain three-dimensional coordinates over a wide range.
[0014]
According to the wafer insertion adjustment method of the present invention, since the coordinate value can be obtained by aligning the actual wafer and the wafer carrier, it is possible to easily inspect the transfer arm. In this inspection method, the position of the contact is generated by moving the transfer arm up and down and left and right on the computer of the transfer device, and the contact coordinates at six locations can be obtained. There is no need to visually check the carrier contact, and the carrier can be automated.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 illustrating an embodiment of the present invention shows a metallized pattern of an inspection wafer. In the drawing, reference numeral 1 denotes a Si wafer, 2 denotes a metallized pattern on the periphery of the wafer, and 3 denotes a metallized pattern provided on the back surface of the central portion of the wafer. The Si wafer 1 is 8 inches in size and has a specific resistance of several tens of Ωcm. Then, the metallized pattern is made of tungsten or molybdenum as a base, and gold is laminated and deposited to obtain ohmic properties. The transfer arm is adjusted by contacting two opposing patterns of the metallized pattern on the peripheral edge with electrodes provided on the left and right sides of the wafer carrier described later.
[0016]
FIG. 1 shows an outline structure of a wafer carrier in which metal electrodes are embedded. In the figure, 4 is a wafer carrier housing, 5 is a housing side wall, 6 is a bar, 7 is a metal electrode provided on the upper portion of the bar, 8 is a metal electrode provided on a lower portion of the bar, 9 is provided on the inner side of the side wall. Metal electrode. If the metal electrode was soft, it would be a source of particles when it came into contact with the wafer, so a 0.5 mm thick tungsten electrode was used. The metal electrode may be a metal or a non-metallic material as long as it is a conductive material. Since it is necessary to draw signal lines from the upper and lower rails in the space for inserting 25 wafers and the metal electrodes on the inner walls of the left and right wafer carrier housings, there is a distance of 152 between the carrier and the wafer contact detection device (described later). The connection was made using a core flat cable. (Cables and connectors are not shown)
The movement of the transfer arm is controlled by a computer, and is controlled by three numerical values: a rotation angle about the arm mounting axis, an arm height, and a distance from the arm rotation axis. Data for inserting a wafer into a predetermined stage is prepared in a storage device of a computer for each wafer carrier.
[0017]
FIG. 4 is a diagram showing a system configuration for performing wafer insertion adjustment of the present invention. In the figure, 10 is a wafer carrier, 11 is a transfer device, 12 is a transfer arm, 13 is a wafer holder, 14 is an inspection wafer, 15 is a contact detection device, and 16 is a transfer arm control computer. The contact detection device 15 allows a current flowing through a specific metal electrode provided on the wafer carrier, a peripheral metallization pattern of the inspection wafer 14, a crystal part of the Si wafer, a metallization pattern for the wafer holder, and a current flowing through the wafer holder to flow into the load resistor. The voltage generated at both ends is converted into "0" and "1" signals by a comparison circuit, encoded into 8-bit or 16-bit data, and output to the computer 16. The adjustment procedure of the wafer insertion adjustment will be specifically described below.
[0018]
An inspection wafer 14 mounted on a working stage of an etching apparatus or an exposure apparatus is fixed to the wafer holder 13 of the transfer arm 12 by suction or dropping, and the transfer arm 12 is inserted into a predetermined stage by the transfer arm 12 of the wafer carrier 10. Get closer to your eyes.
1: The arm is extended from the rotation axis of the transfer arm 12, and the inspection wafer 14 is half inserted into the wafer carrier and stopped.
1 ': If a contact is detected before Step 1 is completed, it is necessary to separately check whether the transfer arm 12 and the computer 16 that controls the transfer arm 12 are operating properly.
2: The inspection wafer 14 is transported until it comes into contact with a metal electrode provided on one of the left and right sides of the wafer carrier 10 housing, and when the contact is detected, the transport is stopped. The position control information at this time is stored.
2 ': When the upper arm 7 of the n-th rail or the lower metal electrode 8 of the (n + 1) -th rail is contacted before contacting the metal electrode 9 on the side surface, the right and left feed of the transfer arm is reversed, for example. After returning by 0.1 mm and moving in the vertical direction by, for example, 0.1 mm, it is moved in the horizontal direction again, and this operation is repeated until it comes into contact with the metal electrode on the side surface. Then, the position control information at this time is stored.
3: The transport arm is moved in the reverse direction, and transported until it contacts the metal electrode on the opposite side. Then, the position control information at this time is stored, an average value with the position control information stored in step 2 is obtained, and the average value is stored as the first left-right direction position control information.
3 ′: When contacting the metal electrode 7 on the upper part of the n-th rail or the metal electrode 8 on the lower part of the (n + 1) -th rail before contacting the metal electrode on the side surface in step 3, the same as step 2 ′ And stores it as first new left-right direction position control information in the same manner as in step 3.
4: The transfer arm is moved based on the first left / right position control information obtained in the step 3, and the arm is moved downward by, for example, 0.1 mm at a time to come into contact with the upper metal electrode 7 of the n-th crosspiece. Obtain position control information.
5: Conversely, move upward by 0.1 mm to obtain position control information for contacting the lower metal electrode 8 of the (n + 1) -th stage rail. This is averaged with the position control information in step 4 and stored as first vertical position control information.
6: Based on the new left-right and up-down position control information obtained in Steps 3 and 5, move the transfer arm in the depth direction until the inspection wafer is completely inserted into the wafer carrier housing. 5, the second new left / right and up / down position control information is obtained, the first and second left / right and up / down position control information are averaged, and the new left / right and up / down position control information to be used for future control is obtained. It is stored as vertical position control information.
6 ′: When contact is made with any of the six metal electrodes before reaching the predetermined depth, the same processing as in steps 1 to 5 is performed, and the center control in the horizontal direction and the vertical direction at that depth position The position is obtained, compared with the previously obtained new position control information in the left, right, up and down directions, and the position control information at a predetermined depth position is obtained in a proportional relationship, and if the difference value is within a predetermined allowable range, Then, the transfer arm is moved to a predetermined position, and the step 6 is performed again. If it exceeds the allowable range, review the accuracy of the transfer arm itself or perform three-dimensional dimension measurement on the wafer carrier to investigate the cause of the failure in control.
[0019]
In the present invention, the insulating wafer carrier has been disclosed. However, the same effect can be obtained with a conductive wafer carrier as long as the metal electrodes are insulated from each other.
Further, in the present invention, the embodiment in which the metal electrode is provided and the wafer carrier is used in the process has been described, but it may be regarded as an adjusting jig for inspecting the transfer arm.
[0020]
The present invention is summarized as follows.
(Supplementary Note 1) In an insulating wafer carrier provided with a multi-stage bar for accommodating a plurality of wafers, an upper surface of the bar for mounting the wafer, a lower surface of a bar located above the bar, and the multi-stage. A metal electrode embedded in each of inner surfaces of a wafer carrier housing for holding the crosspiece, thereby exposing a surface of the metal electrode.
(Supplementary Note 2) The metal electrodes provided on the upper surface, the lower surface, and the inner side surface of the crosspiece of the wafer carrier have a length in a depth direction from an entrance of the wafer carrier longer than at least a radius of the wafer. The described wafer carrier.
(Supplementary Note 3) An ohmic contact with respect to the wafer is provided at least at a portion of the peripheral portion of the wafer that contacts the crosspiece and the inner surface of the wafer carrier and a portion of the front or rear surface of the wafer that contacts the wafer holder of the transfer arm. An inspection wafer, wherein a metallized pattern having a characteristic is formed.
(Supplementary Note 4) The inspection wafer according to Supplementary Note 3, wherein the metallized pattern provided on the peripheral portion of the wafer is a ring-shaped part and is divided into two or more pieces.
(Supplementary Note 5) Using the inspection wafer and the wafer carrier, electrically detecting that the metal electrode of the wafer carrier is in contact with the metallized pattern of the inspection wafer, and adjusting the transfer arm. A wafer insertion adjustment method characterized by the above-mentioned.
[0021]
【The invention's effect】
If the method of adjusting the transfer arm using the wafer carrier and the inspection wafer of the present invention is used, the presence or absence of rubbing between the wafer carrier rail and the wafer, which has conventionally occurred in a place where it is difficult to peep, is automatically controlled by a computer to determine the appropriate wafer. Since position control information can be obtained for each stage of each carrier, the maintenance and inspection of the transfer arm and the wafer carrier can be made more efficient, and there is an effect of suppressing generation of particles and wafer damage accidents which are problematic in the process.
[Brief description of the drawings]
FIG. 1 is a view showing an outline structure of a wafer carrier in which metal electrodes are embedded. FIG. 2 is a view showing a shape of an inspection wafer provided with a metallized pattern. FIG. 3 is a view showing a state where a wafer is mounted on a wafer carrier. FIG. 4 is a diagram showing a system configuration for performing wafer insertion adjustment of the present invention.
DESCRIPTION OF SYMBOLS 1 Si wafer 2 Peripheral part metallization pattern 3 Backside central part metallization pattern 4 Wafer carrier case 5 Side wall 6 Crosspiece 7 Metal electrode provided on the upper part of the rail 8 Metal electrode provided on the lower part of the rail 9 Metal electrode provided on the side wall of the wafer carrier Reference Signs List 10 wafer carrier 11 transfer device 12 transfer arm 13 wafer holder 14 inspection wafer 15 contact detection device 16 transfer arm control computer

Claims (3)

In an insulating wafer carrier provided with a multi-stage bar for accommodating a plurality of wafers, an upper surface of the bar for mounting the wafer, a lower surface of the bar located above the bar, and holding the multi-stage bar A metal electrode embedded in each of inner surfaces of a wafer carrier housing to expose a surface of the metal electrode. Forming a metallized pattern having ohmic properties with respect to the wafer at least at a portion of the peripheral edge of the wafer that contacts the crosspiece and the inner surface of the wafer carrier and at a portion that contacts the wafer holder on the front or back surface of the wafer. Inspection wafer characterized by having done. Using the inspection wafer and the wafer carrier, electrically detecting contact between the metal electrode of the wafer carrier and the metallized pattern of the inspection wafer, and adjusting a transfer arm. Wafer insertion adjustment method.

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