JPH05206249A - 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 peripheral part of an object 18 to be processed mounted on a prealignment stage 30 of a rotary means 50 is irradiated with ultrasonic wave M from an ultrasonic transmitting part 54 arranged above the object, and the reflected wave is received with an ultrasonic wave receiver 56. Since the amount of the reflected ultrasonic wave is proportional to the area of a reflecting surface, the output decreases when a notch passes a measuring part. Hence a control part 58 can recognize the position of the notch, 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]

In order to solve the above-mentioned problems, a first invention is directed to rotating means for rotating an object to be processed having a notch, and rotating means for detecting a rotation angle of the rotating means. An angle detecting means, an ultrasonic wave transmitting unit for irradiating ultrasonic waves so that the irradiation cross section extends over a contour not including a notch on the surface of the object to be processed, and an ultrasonic wave reflected from the peripheral part of the object to be processed. An ultrasonic wave receiving unit for receiving a sound wave, and recognizing the position of the notch of the object to be processed based on the output of the ultrasonic wave receiving unit and the output of the rotation angle detecting means, and the recognized notch A control unit for directing the notch of the object to be processed to a predetermined position by operating the rotating means based on the position. In order to solve the above-mentioned problems, a second aspect of the present invention includes 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, a light transmitting section for irradiating light so as to have an irradiation cross section that crosses over a contour not including a notch on the surface of the object to be processed, While recognizing the position of the notch of the object to be processed based on the output of the light receiving part that receives light reflected from the peripheral part of the object to be processed, and the output of the light receiving part and the rotation angle detecting means, A control unit 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.

[0005]

According to the first aspect of the invention, ultrasonic waves are emitted from the peripheral part of the object to be processed by emitting ultrasonic waves to the peripheral part of the object to be processed rotated by the rotating means from above. The reflected wave is reflected upward, and the reflected wave is received by the ultrasonic wave reception unit. The variation of the output signal in the receiving unit varies depending on the amount of the reflected wave, that is, whether the notch passes through the ultrasonic wave 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. Then, 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.

According to the second invention, the ultrasonic wave is emitted from the light transmitting section to the peripheral portion of the object to be processed which is being rotated by the rotating means, whereby the light is reflected upward from the peripheral part of the object to be processed, This reflected light is received by the light receiver. The fluctuation of the output signal in the light receiving unit fluctuates depending on the amount of the reflected wave, that is, whether the notch passes through the ultrasonic wave irradiation unit. Therefore, the control unit outputs the output value of the receiving unit at this time,
By performing a predetermined process based on the output value of the rotation angle detection means, it is possible to recognize the position of the notch formed in the object to be processed in association with the rotation angle. Then, 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.

[0007]

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 section 6 is composed of, for example, an independent casing having a depth of 1000 mm, a width of 380 mm and a height of 1200 mm. 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 the 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, an ultrasonic wave transmitting section 54 for emitting an ultrasonic wave, an ultrasonic wave receiving section 56 for receiving the ultrasonic wave reflected from the wafer, the receiving section 56 and the rotation angle. Detection means 5
2 and the position of the notch based on the output of the control unit 58, and based on this recognition result, the rotating unit is operated 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 upper surface of the stage 30 so that the wafer 18 can be sucked on the upper surface thereof, and the entire stage 30 is vertically movable (Z direction).

The stage motor 60 is connected to a rotation angle detecting means 52 such as an encoder, and its output is input to the control section 58.
The ultrasonic transmission unit 54, for example, a built-in oscillating portion which oscillates an ultrasonic wave of about 500KH _z, directly above, for example, 5 of the contour L of circumference without the notch 18A of the wafer 18
It is installed with a distance of about 0 mm. Then, the ultrasonic wave is radiated toward the peripheral portion of the lower wafer from here in a pulsed manner, and as shown in FIGS. 6 to 7, the irradiation cross section S (FIG. 6) in the same horizontal plane as the wafer at that time (FIG. The cutout 18A of the above wafer is indicated by the medium wave line).
The ultrasonic wave is radiated so as to straddle the contour L that does not include.

Preferably, the center of the transmitter 54 is located right above the contour L. Further, the size of the irradiation cross section S has a flat contour L1 of the orientation flat or the cutout 18A assuming that the center O is on the contour L as shown in FIG.
To the extent that the outer circumference of the irradiation cross section S is in contact with, for example, diameter 20 mm
It is preferable to set the peak value or the bottom of the output value clearly as will be described later. This setting
This can be easily performed by adjusting the height of the ultrasonic transmitter 54. An ultrasonic wave reception unit 56 is arranged in parallel with the ultrasonic wave transmission unit 54 at a distance of, for example, a few mm, and an output signal (voltage) is output according to the reflection amount of the ultrasonic wave from the peripheral portion of the wafer. Is configured to issue.
Therefore, when the notch 18A of the wafer passes downward, the amount of reflection of ultrasonic waves decreases, so that the position of the notch can be determined by corresponding to the rotation angle of the wafer at that time.

The output of the receiver 56 is connected to the A / D converter 62 of the controller 58 including a microcomputer, and the output of the converter 62 is connected to the CPU 64. The CPU 64 is also connected to the output from the rotation angle detecting means 52, and is connected to a ROM 66 in which various processing programs are stored, so that predetermined calculation is performed as necessary. There is. 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 is configured to appropriately output a tweezers drive signal to the tweezers motor drive circuit 68 and a stage drive signal to the stage motor drive circuit 70 as a result of the calculation, and inputs the above signals. Each of the circuits 68 and 70 is configured to appropriately drive the tweezers motor 22 and the stage motor 60 to adjust the amount of eccentricity and orient the position of the notch of the wafer.

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 ultrasonic wave M from the ultrasonic wave transmitting unit 54 toward the peripheral portion of the wafer, the pre-alignment stage 30 is rotated at a predetermined speed, for example, 1 rotation / second, and the reflected wave is received by the ultrasonic wave. It is received by the unit 56. A typical output waveform when the wafer is eccentrically placed is a sine curve as shown in FIG.
0 indicates a portion where the orientation flat or notch 18A of the wafer has passed through the measurement portion and the reflected wave of ultrasonic waves has decreased.

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. 8 is obtained from the output value from the rotation angle detection 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 of FIG. 8A is obtained, and 1/2 of this difference D1 is the eccentric 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. 8B. 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. 8B 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 ultrasonic wave receiver 56 is used.
However, the receiving unit may be arranged anywhere near the transmitting unit as long as it can receive the reflected ultrasonic waves from the wafer. Further, the size of the ultrasonic irradiation cross-section S on the horizontal level surface of the wafer is set so as to be in contact with the flat contour L1 of the notch as shown in FIG. 7, but is not limited to this. The diameter of the irradiation cross section S may be increased or decreased as long as the change in the reflection amount of the ultrasonic wave can be captured when the notch 18A passes through the measurement section. The center O may be moved outward or inward in the radial direction of the wafer for measurement. 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 a notch formed in, for example, an 8-inch wafer as shown in FIG. It can also be applied to the case of detecting a relatively small semicircular notch 81. In this case, the size of the ultrasonic irradiation cross section on the horizontal level surface of the wafer is set to be small so that the fluctuation amount of the reflected ultrasonic waves can be sufficiently detected, and the change in the size of the wafer diameter can be dealt with. First, the ultrasonic transmitter 54 and the receiver 56 are configured to be movable in the radial direction of the wafer.

Further, in the above embodiment, the ultrasonic wave was used as the measurement wave, but instead of this, light may be used as the second invention as shown in FIG. That is, instead of the ultrasonic wave transmitting unit, a light transmitting unit 82 including an LED that emits red light H is installed above the peripheral portion of the wafer 18, and the ultrasonic wave receiving unit serves as a member that receives reflected light from the wafer. Instead, for example, a light receiving section 84 such as a light receiving element is provided, and the receiving section 84 receives the reflected light reflected from the peripheral portion of the wafer and photoelectrically converts it.
The configuration of the latter stage of the light receiving unit 84 is exactly the same as the configuration shown in FIG. 1 described above, and performs the same signal processing. In this case, the diameter of the irradiation cross section on the horizontal level surface of the wafer can be set to about 2 mm in diameter, which is smaller than that in the case of ultrasonic waves. Therefore, when the notch area is relatively small like the notch of an 8-inch wafer. When applied, the output fluctuation rate becomes larger than that in the case of ultrasonic waves, and it becomes possible to improve the detection accuracy. Furthermore, in the above embodiments, the case where the notch of the substantially circular semiconductor wafer is detected has been described, but the present invention is not limited to this, and the present invention can be applied to, for example, an LCD substrate or the like formed on a glass substrate. Can be applied. 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 surface of the peripheral part of the object to be processed is irradiated with ultrasonic waves or light and the amount of reflection 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 a partially enlarged view showing a part of the object to be processed.

FIG. 7 is an enlarged view showing a notch in the object to be processed.

FIG. 8 is a waveform diagram showing an output waveform of an ultrasonic wave receiving unit.

FIG. 9 is an enlarged view showing another type of notch in the object to be processed.

FIG. 10 is an enlarged view showing a main part of the second invention.

[Explanation of symbols]

 2 Positioning device 4 Probe device 18 Semiconductor wafer (object to be processed) 18A Notch 20 Vacuum suction tweezers 30 Pre-alignment stage 50 Rotating means 52 Rotation angle detecting means 54 Ultrasonic wave transmitting section 56 Ultrasonic wave receiving section 58 Control section 82 Optical transmission Section 84 light receiving section H light L contour L1 flat contour M ultrasonic wave S irradiation cross section

Claims (2)

[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 contour not including a notch on a surface of the object to be processed. An ultrasonic wave transmitting unit that irradiates ultrasonic waves so as to have an irradiation cross section that straddles, an ultrasonic wave receiving unit that receives ultrasonic waves reflected from the peripheral portion of the object to be processed, an output of the ultrasonic wave receiving unit, and the The position of the notch of the object to be processed is recognized based on the output of the rotation angle detection means, and the notch of the object to be processed is operated by operating the rotating means based on the position of the recognized notch. And a control unit for directing the to a predetermined position. 2. 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 contour not including a notch on a surface of the object to be processed. A light transmitting unit that irradiates light so as to have an irradiation cross section that straddles, a light receiving unit that receives light reflected from the peripheral portion of the object to be processed, the output of the light receiving unit, and the rotation angle detection unit. While recognizing the position of the notch of the object to be processed based on the output, by operating the rotating means based on the position of the recognized notch to position the notch of the object to be processed to a predetermined position. An alignment device configured to include a control unit for directing.