JPS6046361B2 - alignment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alignment device for aligning two parallel objects.

For example, when precisely aligning two objects, a mask for VLSI X-ray transfer, to a 78LSI pattern drawn on a wafer, it is necessary to roughly align the mask and the wafer as a preliminary step.

Conventionally, in order to roughly align the mask and wafer,
A microscope is inserted into the line transfer device, and while observing the VLSI patterns on the mask and wafer, a holding mechanism such as a moving table that holds the mask or wafer is manually operated to align them relative to each other. I was getting used to it. However, when aligning the mask and wafer using this method, the microscope must be inserted into the X-ray transfer device, and the operator must position the wafer or mask while looking through the microscope with the naked eye. Not only does the work require a lot of time and effort, and the workability is extremely poor, but also there are drawbacks such as large variations in alignment accuracy depending on the skill level of the worker.

This invention was made based on the above-mentioned circumstances, and its purpose is to automatically perform relative positioning of two objects using a diffraction grating, thereby improving work efficiency and uniformizing accuracy. An object of the present invention is to provide a positioning device that can measure.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

1 in the figure is a holding mechanism. This holding mechanism 1 includes a mask holder 2 and an XY
This XY table 3 consists of a drive source 4
It is designed to be driven in the X and Y directions by. Above: A mask 5 as a first object is held in the mask holder 2, and a wafer 6 as a second object is held on the upper surface of the epithelium Y table 3 so as to be parallel to the mask 5. A first pattern 9 consisting of a rectangular opaque frame 7 and a transparent portion 8 surrounded by the frame 7 is formed at the corner of the mask 5, and a first pattern 9 is formed on the wafer 6.
A second pattern 10 is formed at a corner corresponding to the pattern 9. In this second pattern 10, the first to fourth diffraction gratings 11 to 14 are arranged so that the body has a square shape with a larger area than the light-transmitting part 8, and each of the diffraction gratings 11 to 14 The directions of the marked lines differ by 45 degrees. A laser oscillator 15 as a light source device is disposed above the holding mechanism 1.

The laser beam L, which is a coherent beam outputted from the laser oscillator 15, is reflected by a reflecting mirror 16a and then passes through the light-transmitting portion 8 of the first pattern 9, and passes through the diffraction gratings 11 to 14 of the second pattern 10. irradiate. Then, a plurality of diffracted lights are generated from the first to fourth diffraction gratings 11 to 14, respectively, in directions corresponding to these score line angles, and among them, the +1st-order diffraction light beams ~ L4 are generated from the first to fourth diffraction gratings 11 to 14. The light is received by optical sensors 16-19. These optical sensors 16 to 19
is connected to the signal processing circuit 20. This signal processing circuit 20 compares the signals from each of the optical sensors 16 to 19, that is, the amount of received light, and drives the drive source 4 based on this comparison value. Next, the operation of the above configuration will be explained. Once the mask 5 and wafer 6 are held on the mask holder 2 and the XY table 3 of the holding mechanism 1, respectively, so that the first pattern 9 and the second pattern 10 correspond to each other, the laser oscillator 15 is activated. Activate it to output laser light L. Then, this laser beam L is reflected by the reflecting mirror 16a, passes through the light transmitting portion 8 of the first pattern 9, and irradiates the second pattern 10, so that each of the diffraction gratings 11- The +1st-order diffracted lights L1 to L4 generated from the photodetector 14 are received by each of the optical sensors 16 to 19, and the amounts of the j received light are compared by the signal processing circuit 20. Then, the drive source 4 operates based on this comparison value,
The XY table 3 is driven so that the amounts of light received by each of the optical sensors 16 to 19 are equal. That is, if the positions of the mask 5 and the wafer 6 in the X and Y directions match, the light-transmitting portion 8 of the first pattern 9 is transferred to the second pattern 1 as shown in FIG.
Each of the diffraction gratings 11 to 14 of 0 faces the same area.

Therefore, since the intensity of the +1st-order diffracted light L upper 4 generated from each diffraction grating 11 to 14 is equal, each optical sensor 16
~19, the amount of light received is the same. However, if the relative positions of the mask 5 and the wafer 6 are shifted in the +X direction as shown in FIG. , which face the light-transmitting portion 8 over a larger area than the fourth diffraction gratings 12 and 14. Therefore, the first and third diffraction gratings 11,
The +1st-order diffracted light Ll and light L generated from 13 are the second and fourth
The +1st-order diffracted light generated from the diffraction gratings 12 and 14, L
4, there is a difference in the amount of light received by each optical sensor 16 to 19, and a signal corresponding to this difference in light amount is output to the signal processing circuit 20. - Driven in the X direction. And each optical sensor 16
~19 continuously receives the +1st-order diffracted lights L1 to L4,
When the amount of light received by each of the optical sensors 16 to 19 becomes equal, the XY table 3 stops, and the second pattern 10, that is, the mask 5 and the wafer 6, are positioned relative to the first pattern 9. Furthermore, if there is a shift in the Y direction, the wafer 6 is positioned in the same way as in the X direction. Note that the present invention is not limited to the above-mentioned embodiment; for example, two first and second patterns may be formed on the first object and the second object, respectively.
By providing the first object and the second object at an angle of 80 degrees or 90 degrees, it is possible to align the first object and the second object not only in the XY directions but also in the rotational direction.

Moreover, a plurality of diffraction gratings 1 constituting the second pattern 10
1 to 14, the pitch of the scored lines may be changed as shown in FIG.

Furthermore, the intensity distribution of the laser beam L is usually strongest at the center;
Since the glass has a distribution that becomes weaker toward the periphery, if the optical axis of the laser beam L does not coincide with the transparent portion 8 of the first pattern 9, each diffraction grating 11 to 14 is irradiated. Since the intensity of the laser beam L is non-uniform from the beginning, an error occurs in alignment.

In order to eliminate such errors, as shown in FIG.
Draw numbers 1 to 24. However, in the fifth to eighth diffraction gratings 21 to 24, the direction of the scored lines or the width of the scored lines is narrower than that of the first to fourth diffraction gratings 11 to 14,
In addition, the concentration is made thin so that most of the laser beam L can pass through. Further, above the holding mechanism 1, as shown in FIG. 9, fifth to eighth optical sensors 25 to 28 are arranged to receive the diffracted lights from the fifth to eighth diffraction gratings 21 to 24. Then, the light amount of the diffracted light L4 received by the first to fourth optical sensors 16 to 19 is set to 116, 117, 1
18,119, and the fifth to eighth optical sensors 25 to 28
The amount of light received at 125, I. 2f5, 127, 12
8, or if the XY table 3 is driven and controlled by the output from the signal processing circuit 20 so that the equations (2) and (3) are obtained, the intensity distribution of the laser beam L is non-uniform. Even if the mask 5 and the wafer 6 are the same, the mask 5 and the wafer 6 can be accurately aligned.

Furthermore, it goes without saying that the alignment according to the present invention can be applied not only to a mask and a wafer but also to other two objects, such as an IC automatic bonder.

As described above, the present invention holds a first object and a second object in parallel by a holding mechanism, forms a first pattern serving as a light-transmitting part on the first object, and a second object. The object has multiple diffraction gratings.Azuna4 [(n
A second pattern is formed, and coherent light is irradiated onto the diffraction grating through the transparent part, and the diffracted light from these diffraction gratings is received by each optical sensor, so that the amount of light received by each optical sensor is equal. The first object or the second object is controlled to be driven through the holding mechanism so that the holding mechanism holds the first object or the second object.

Therefore, there is an advantage that the alignment between the first object and the second object can be performed automatically, efficiently, and accurately.

[Brief explanation of the drawing]

1 to 6 show one embodiment of the present invention, FIG. 1 is a schematic configuration diagram, FIG. 2 is a plan view showing the arrangement state of the optical sensor, and FIG. 3 is a plan view of the first pattern. Figure 4 is the second
5 and 6 are explanatory diagrams showing the states of the first pattern and the second pattern with respect to the relative positions of the first object and the second object, respectively, and FIG. 7 is a plan view of the pattern. FIGS. 8 and 9 are plan views of a diffraction grating showing other embodiments of the present invention, FIG. 8 is a plan view of a first pattern, and FIG. 9 is a plan view of a first pattern. FIG. 3 is a plan view showing the arrangement of optical sensors. DESCRIPTION OF SYMBOLS 1... Holding mechanism, 4... Drive source (control means), 5...
...Mask (first object), 6... Wafer (second object), 8... Transparent part, 9... First pattern, 10
...Second pattern, 11-14...Diffraction grating, 1
5...Talaser oscillator (light source device), 16-19...
Optical sensor, L... Loser light (coherent light), L4...
・Diffraction light.

Claims (1)

[Claims] 1. A holding mechanism that holds a first object and a second object in parallel, a first pattern having a light-transmitting portion provided on the first object, and a holding mechanism that holds a first object and a second object in parallel; a second pattern consisting of a plurality of diffraction gratings provided in the first pattern; a light source device that irradiates the diffraction grating of the second pattern with coherent light through the transparent portion of the first pattern; A plurality of optical sensors each receive diffracted light from each irradiated diffraction grating, and the amount of diffracted light received by each optical sensor is compared, and based on this comparison value, the amount of light received by each optical sensor is maintained to be equal. A positioning device comprising: a control means for operating a mechanism to move the first object or the second object. 2. The alignment device according to claim 1, wherein the plurality of diffraction gratings of the second pattern have different score line directions or score line pitches.