JPH05206250A - Alignment equipment - Google Patents

Abstract

PURPOSE:To accurately detect a notch and perform alignment, independently of whether material constituting an object to be processed is transparent. CONSTITUTION:The outer end surface 59 of an object 18 to be processed which is mounted on a prealignment stage 30 of a rotary means 50 is irradiated with laser light M from a laser light transmitting part 54 arranged in the horizontal direction of the object. The reflected wave is received with a laser light receiving part 56, and the image is formed. Since the imagery position, i.e., the output, changes according to the distance of the outer end surface 59, the output changes when a notch passes a measuring part. Hence a control part 58 can recognize the position of the notch by processing the output signal, and drives the rotary means 50 according to the recognition result and the output result of a rotation angle detecting means 52. Thereby the notch of the object 18 to be processed is set at a specified position.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alignment device.

[0002]

2. Description of the Related Art Generally, when a semiconductor wafer is subjected to a predetermined process, for example, dry etching, or a product inspection is conducted by contacting a probe or the like for characteristic inspection with a wafer in the process of manufacture, First, it is necessary to orient the semiconductor wafer itself in a predetermined direction and perform its alignment, that is, pre-alignment. Usually, as a reference mark for performing such alignment, a notch is formed on a semiconductor wafer, for example, an orientation flat (hereinafter referred to as an orientation flat) on a 6-inch wafer, and a notch is formed on an 8-inch wafer. ing. A conventional alignment apparatus is, for example, disclosed in Japanese Patent Laid-Open Nos. 58-210633 and 60-80241, above a peripheral portion of a semiconductor wafer suction-supported on a rotary table. A light emitting element or the like is provided, and the light emitting element is arranged in line symmetry with the light emitting element centering on the semiconductor wafer. The position of the orientation flat or notch on the wafer is recognized by processing the output of the light emitting element while rotating the semiconductor wafer, and based on the result, the orientation table of the wafer is stopped by stopping the rotary table at a predetermined rotation angle. Orient it in place.

[0003]

By the way, in the conventional apparatus as described above, the amount of light at which the portion such as the orientation flat of the wafer to be processed blocks or does not block the light from the light emitting element. Since the position is confirmed from the change, no problem occurs when the object to be processed is a member that does not transmit light, for example, a silicon wafer.
When this object is made of a material that transmits light, for example, glass, crystal, or SOS (silicon on sapphire), the amount of light in the light emitting element even if the orientation flat passes between the light emitting element and the light receiving element. Since there is almost no change, there is an improvement in that the above conventional device cannot be used. The present invention has been made to pay attention to the above problems and to solve them effectively.
An object of the present invention is to provide a positioning device that can perform accurate positioning regardless of whether the material forming the object to be processed is transparent or opaque.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to rotating means for rotating an object to be processed having a notch and rotation angle detection for detecting the rotation angle of the rotating means. Means, a laser light transmitter for irradiating a laser beam so as to form an irradiation cross section that crosses a contour not including a notch on the surface of the object to be processed, and a laser light reflected from a peripheral part of the object to be processed. Receiving a laser beam receiving unit, recognizing the position of the notch of the object to be processed based on the output of the laser beam receiving unit and the output of the rotation angle detecting means, and at the position of the recognized notch. And a control unit for directing the cutout of the object to be processed to a predetermined position by operating the rotating means.

[0005]

Since the present invention is configured as described above, the laser light is emitted from the laser light transmitting section to the outer end surface of the object to be processed which is being rotated by the rotating means, so that the laser light is emitted from the outer end surface of the object to be processed. For example, the reflected wave is reflected in the horizontal direction, and the reflected wave is received by the laser light receiving unit. The fluctuation of the output signal in the receiving unit changes depending on the image forming position of the reflected wave, that is, whether or not the notch passes through the laser light irradiation unit. Therefore, the control unit performs a predetermined process based on the output value of the receiving unit and the output value of the rotation angle detection unit at this time to associate the position of the notch formed in the object with the rotation angle. Can be recognized. And
Based on this recognition result, the control unit stops the rotating means at an appropriate rotation angle to direct the notch of the object to be processed to a predetermined position, and the alignment is performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the alignment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. 1 is a configuration diagram showing an alignment device according to the present invention, FIG. 2 is a schematic perspective view showing the alignment device shown in FIG. 1, and FIG. 3 is a plan view showing a probe device equipped with the alignment device shown in FIG. 4, FIG. 4 is a front view of the probe apparatus of FIG. 3, and FIG. 5 is an explanatory view of a loader section of the probe apparatus of FIG. As shown in FIGS. 3 to 5, the alignment device 2 according to the present invention is incorporated in the probe device 4. First, the entire probe device 4 will be described. The probe device 4 has a configuration in which a prober unit 9 also formed in an independent housing is arranged on a side surface of a loader unit 6 formed in an independent housing.

As shown in FIG. 5, the loader unit 6 is composed of an independent casing having a depth of 1000 mm, a width of 380 mm, and a height of 1200 mm, for example. The side surface of the loader portion 6 is composed of a detachable side surface plate, and this side surface plate is attached and detached by screwing bolts at a total of eight positions of the peripheral edge square and the midpoint of each corner. As the internal configuration of the loader unit 6, the entire surface side is a cassette storage unit 8. A motor 10 is connected to the housing portion 8, and four rotatable guide shafts 12 are installed in the vertical direction along the side surface of the housing of the loader portion 6 with respect to the two guide shafts 12. And one side of one cassette mounting table 14 is attached. That is, the guide shaft 12 is rotated by the rotation of the motor 10, the mounting table 14 is moved up and down in accordance with this rotation, and the cassette 16 mounted on the mounting table 14 is moved up and down. Two cassettes 16 can be placed in the cassette storage portion 8, each of which is an object to be processed, and 25 semiconductor wafers 18 each having semiconductor chips regularly formed are stored at appropriate intervals. ing.

The vacuum suction tweezers 20 for loading and unloading the wafer 18 from the cassette 16 are provided with a support rod 26 vertically on a horizontally configured rotating shaft 24 connected to a tweezer motor 22. It is installed. With this structure, the vacuum suction tweezers 20 can slide in parallel. Further, from the tip end of the tweezers 20 to the central portion is formed by a suction portion 28 in the form of two parallel plates, and from the central portion to the installation portion of the support rod 26 is formed in the state of a single plate. .. Between the vacuum suction tweezers 20 and the cassette housing portion 8, a rotatable pre-alignment stage 30 that constitutes a part of the alignment device 2 according to the present invention described later is provided so that the wafer 18 can be placed. .. In addition, the wafer 1 is transferred from the pre-alignment stage 30 to the measurement stage 32 of the prober unit 9.
Vacuum suction arm 34 that slides and conveys 8
Is installed. The arm 34 is connected to a motor (not shown) and can rotate 360 ° in a horizontal plane. On the rear surface side of the loader unit 6 above the housing, a pillar 36 is provided.
An arm 38 is attached to the column 36, which is rotatable about this by 360 ° in the horizontal plane. A microscope 40 for enlarging the chip is installed at the tip of the arm 38, and for example, a microscope 40 is installed in the vertical direction.
It can move up and down mm. A CPU (not shown) is incorporated in the loader unit 6 to control this operation, and is wired to a keyboard 42 that is detachably installed on the upper surface of the loader unit casing. In addition, the power supply 44
Are arranged so that power can be supplied to the prober unit 9.

Next, the prober unit will be described. The prober unit 9 is composed of, for example, an independent casing having a depth of 1000 mm, a width of 620 mm, and a height of 1200 mm. Both side surfaces of the prober unit 9 are detachable by simply screwing bolts at eight positions so that the loader unit 6 can be set on either side. The eight points are the squares of the peripheral portion of the housing of the prober unit 9 and the midpoints of the respective corners. As an internal configuration, the measurement stage 32 is a well-known means, and the X direction, the Y direction, the Z direction,
It can be driven in the θ direction and is configured for fine alignment operation. In addition, a probe card is set at a position facing the measurement stage 32 at the measurement position, and the measurement is performed by a known means. The operation of the prober unit 9 is input from the operation panel unit 46 as shown in FIG.
U performs arithmetic processing to control each operating mechanism.

On the other hand, as shown in FIGS. 1 and 2, the alignment apparatus 2 according to the present invention for pre-aligning an object to be processed has a rotating means 50 for rotating the semiconductor wafer 18 as the object to be processed, and this rotation. A rotation angle detecting means 52 for detecting the rotation angle of the means 50, a laser light transmitting portion 54 for emitting a laser light, a laser light receiving portion 56 for receiving the laser light reflected from the wafer, the receiving portion 56 and the rotation angle. The control unit 58 mainly recognizes the position of the notch based on the output from the detecting unit 52 and operates the rotating unit based on the recognition result to direct the notch to a predetermined position. .. Specifically, the rotating means 50 is mainly composed of the pre-alignment stage 30 and a stage motor 60 such as a step motor for rotating the pre-alignment stage 30. A vacuum suction mechanism (not shown) is provided on the stage 30 so that the wafer 18 can be suctioned on the upper surface thereof, and the entire stage 30 is in the vertical direction (Z direction).
It can be raised and lowered freely.

The stage motor 60 is connected to a rotation angle detecting means 52 such as an encoder, the output of which is input to the control section 58.
The laser light transmitter 54 is provided on an extension of the horizontal plane of the wafer on the stage, that is, in the horizontal direction as shown in the drawing, and the transmitter 54 has, for example, a wavelength of 670 nm.
Semiconductor laser element 55 that emits red laser light M of a certain degree
And a laser drive circuit 57 for driving the laser element 55.
And a projection lens 61 that irradiates the laser light M from the laser element 55, and is configured to accurately irradiate the condensed laser light M onto the outer end surface 59 of the wafer. There is.

Generally, the thickness L1 of the wafer 18 is 0.6 mm.
While the spot S of the laser light applied to the outer end surface 59 is an ellipse having an ellipse L2 of about 0.6 mm and a short circle L3 of about 0.3 mm, as shown in FIG. And the distance between the arcuate contour of the wafer and the laser light transmitter 54 is, for example, 5
Set to about 0 mm. Then, the laser light transmitter 5
4, the laser light receiving portions 56 are arranged in parallel with each other at a slight distance of, for example, about 10 mm in the vertical direction or the horizontal direction,
The output signal (voltage) is transmitted according to the image forming position of the laser light reflected from the outer end surface of the wafer. Specifically, the laser light receiving unit 56 collects the laser light reflected or irregularly reflected from the wafer outer end face 59 as shown in FIGS. 6 and 7, and the light from this lens 63. It is mainly configured by a linear sensor 65 that receives light, for example, and is configured so that the imaging position can be moved on the linear sensor 65 according to the distance of the outer end face 59. Therefore, when the notch 18A of the wafer passes through the irradiation portion of the laser light M, the image forming position on the linear sensor 65 moves above it. This makes it possible to determine the position of the notch in the wafer.

The output of the linear sensor 65 of the receiving unit 56 is the A / A value of the control unit 58 including a microcomputer or the like.
It is connected to the D converter 62, and the output of this converter 62 is C
It is connected to the PU 64. Further, the CPU 64 receives the output from the rotation angle detecting means 52 and also stores the various processing programs in the ROM 66.
Are connected, and predetermined calculations are performed as necessary. In the present embodiment, a program for calculating and adjusting the eccentricity amount of the wafer placed on the stage is executed before performing the prealignment operation, and then the prealignment program is executed. Is configured.

Then, the CPU 64, as a result of the calculation,
The tweezers drive signal is appropriately output to the tweezers motor drive circuit 68, and the stage drive signal is appropriately output to the stage motor drive circuit 70. The tweezers motor 22 and the stage motor 60 are driven so that the eccentricity can be adjusted and the position of the notch of the wafer can be oriented.

Next, the operation of this embodiment configured as described above will be described. Each mechanism of the loader unit 6 and the prober unit 9 operates according to a predetermined program input to each CPU. First, two cassettes 16 in which 25 wafers 18 are stored are set in the cassette mounting table 14 of the cassette storage unit 8. The vacuum suction tweezers 20 are slid into the cassette 16 and one wafer 18 is suctioned to the vacuum suction section 28.
Is carried out by the vacuum suction tweezers 20. The vacuum suction part 28 of the vacuum suction tweezers 20 is set at the place where the pre-alignment stage 30 is installed, and the pre-alignment stage 30 is raised there to place the wafer 18 carried out on the pre-alignment stage 30.

When the wafer transfer is completed in this way, next, an eccentricity amount adjusting operation and a notch position directing operation are performed by the alignment device 2 according to the present invention. First, when the transfer is completed as described above, the center of rotation of the pre-alignment stage 30 and the center of the wafer 18 are usually misaligned and it is necessary to match them. Therefore, first, while irradiating the laser light M from the semiconductor laser element 55 of the laser light transmitter 54 toward the outer end surface 59 of the wafer, the pre-alignment stage 30 is rotated at a predetermined speed, for example, 1 rotation / second. The linear light sensor 65 of the laser light receiver 56 receives the reflected light. At this time, if the position of the outer end surface 59 moves in the horizontal direction as the wafer rotates, the image forming position on the linear sensor 65 changes. For example, in FIGS. 6 and 7, if the image forming position of the reflected laser light from the arc portion other than the cutout 18A of the wafer is F1, the image forming position of the reflected laser light from the outer end face of the cutout 18A moves to F2. This movement is output from the linear sensor 65 as a voltage change, for example. Such voltage fluctuations also occur when the wafer is eccentrically placed on the stage 30. That is, a typical output waveform when the wafer is eccentrically placed is a sine curve as shown in FIG. 8A, and the recess 80 in the middle has the orientation flat or notch 18A of the wafer as the measuring portion. The portion where the image formation position by the laser beam has changed abruptly after passing is shown.

This signal is input from the receiving unit 56 to the A / D converter 62 of the control unit 58, converted into a digital signal here, and further input to the CPU 64. Then, in the CPU 64, the eccentricity amount is calculated by a predetermined program stored in the ROM 66. The rotation angle in FIG. 9 is obtained from the output value from the rotation angle detecting means 52. An example of calculating the amount of eccentricity is as follows.
The difference D1 between the peak P1 and the bottom P2 of the sine curve in FIG. 9A is obtained, and 1/2 of this difference D1 is the eccentricity amount. Therefore, the wafer may be moved radially inward or outward from the rotation angle direction corresponding to the peak P1 or bottom P2 by a distance corresponding to the eccentricity so that the difference D1 becomes zero.

Therefore, the pre-alignment stage 30 is appropriately rotated by driving the stage motor 60 via the stage motor drive circuit 70, and the corresponding rotation angle direction of the peak P1 or the bottom P2 is moved in the moving direction of the vacuum suction tweezers 20. To match. Then, while alternately performing the suction vacuum operation of the stage 30 and the tweezers 20, the stage 30 is lowered to transfer the wafer 18 onto the tweezers 20. Then, while holding the wafer, the tweezers 20 is moved in the eccentricity correction direction by the eccentricity. Then, the stage 30 is raised again to support the wafer again. Theoretically, the eccentricity amount becomes zero by this one operation, but since an error is actually included, the above series of operations is performed a plurality of times, that is, the amplitude of the sine curve is a predetermined value as shown in FIG. 9B. Repeat until the following:

When the step of correcting the amount of eccentricity is completed in this way, the step of directing the notch position is next entered. Specifically, since the bottom P3 of the recess 80 in FIG. 9B corresponds to the center position of the cutout 18A,
The stage 30 is arranged so that this part is positioned in a predetermined direction.
Can be rotated. In general, since the output value from the receiving unit 56 contains noise, as one of the bottom (peak) calculation methods that is least affected by these noise components, in this embodiment, for example, a data value is A processing program is stored which is applied to the trigonometric function equation by the least squares method and is processed by the CPU 6.
4 can easily obtain the rotation angle corresponding to the bottom P3. In this way, the notch 18A on the wafer surface
When the center position of the stage is obtained, the stage motor drive circuit 70 is used to reversely feed the pulse so as to rotate the stage by a desired angle, and the stage motor 60 is reversely rotated by a predetermined number of pulses. Of course, it may be rotated forward if necessary. As a result, the stage 30 is rotated by an appropriate angle and the notch 18A of the wafer is positioned in a predetermined direction.

In the above description, the case where the least squares method is used to obtain the bottom P3 has been described, but other methods may be used. In this way, it becomes possible to always orient all the wafers in a certain direction by the pre-alignment operation with the notches formed in each as the reference. The wafer that has undergone the pre-alignment process as described above is moved to the prober 9 by the vacuum suction arm 34.
After being placed on the measurement stage 32 of FIG. 2 and accurately and properly positioned, that is, fine-aligned by a laser recognition mechanism or a pattern recognition mechanism, a probe needle is brought into contact with the electrode pad of each chip on the wafer by a well-known means to electrically perform Take a measurement. When the probe inspection is completed, the wafer is transferred in the reverse direction through the above-mentioned transfer path, and the wafer is stored in the processed cassette.

In the above embodiment, the laser light receiving section 5
Although 6 is arranged in parallel with the laser beam transmitter 54, the receiver may be disposed anywhere near the transmitter as long as it can receive the reflected laser light from the wafer. In particular, in the present embodiment, since the laser light having a uniform phase is used as the measurement wave, it is possible to obtain a high resolution, for example, a resolution of 0.1 mm or less, and an accurate positioning operation can be performed. . Further, in the above embodiment, the size of the laser beam spot on the outer end face of the wafer is set to 0.3 × 0.6.
Although it is set to have an elliptical shape of about mm, it is needless to say that the size is not limited to this.

Further, in the above embodiment, the case where the orientation flat of the 6 inch wafer is detected as the notch has been described, but the present invention is not limited to this, and as shown in FIG. It can also be applied to the case of detecting a relatively small semicircular notch 81 as a notch. In this case, the laser light transmitter 54 and the receiver 56 are configured to be movable in the radial direction of the wafer so as to cope with the change in the diameter of the wafer. Furthermore,
In the above embodiments, the case of detecting a notch in a substantially circular semiconductor wafer has been described, but the present invention is not limited to this, and the present invention is also applied to, for example, an LCD substrate or the like that is film-formed on a glass substrate. be able to. It is needless to say that the present invention can be applied not only to the probe device, but also to other processing devices that require alignment, such as etching devices.

[0023]

As described above, according to the present invention, the following excellent operational effects can be exhibited. Since the outer end surface of the object to be processed is irradiated with laser light and the image formation position of the reflected light is detected, the position of the notch can be reliably ensured regardless of whether the material of the object to be processed is transparent or not. It can be detected, and the orientation of the position of the notch can be accurately performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a positioning device according to the present invention.

FIG. 2 is a schematic configuration diagram showing the alignment device shown in FIG.

FIG. 3 is a plan view showing a probe device including the alignment device shown in FIG.

FIG. 4 is a front view showing the probe device of FIG.

5 is an explanatory diagram showing a loader section of the probe device of FIG. 3. FIG.

FIG. 6 is an explanatory diagram illustrating a method of detecting a position of a notch of a target object.

FIG. 7 is an explanatory diagram illustrating a method of detecting a position of a notch of a target object.

FIG. 8 is a diagram showing spots of laser light applied to the outer edge surface of the wafer.

FIG. 9 is a waveform diagram showing an output waveform of the ultrasonic transmission unit.

FIG. 10 is an enlarged view showing another type of notch in the object to be processed.

[Explanation of symbols]

 2 Positioning device 4 Probe device 18 Semiconductor wafer (processing target) 18A Notch 20 Vacuum suction tweezers 30 Pre-alignment stage 50 Rotating means 52 Rotation angle detecting means 54 Laser light transmitting section 55 Semiconductor laser element 56 Laser light receiving section 57 Laser Drive circuit 58 Control unit 59 Outer end face 61 Light emitting lens 63 Light receiving lens 65 Linear sensor M Laser light F1, F2 Imaging position S Spot

Claims (1)

[Claims] 1. A rotating means for rotating an object to be processed having a notch, a rotation angle detecting means for detecting a rotation angle of the rotating means, and a laser for irradiating an outer end surface of the object to be irradiated with laser light. An optical transmitter, a laser light receiver for receiving laser light reflected from the outer end surface of the object to be processed, an output of the laser light receiver, and an output of the rotation angle detection means based on the output of the object to be processed. A controller for recognizing the position of the notch and for directing the notch of the object to be processed to a predetermined position by operating the rotating means based on the recognized position of the notch. An alignment device having the above structure.