JPH0674965B2 - Alignment method and device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a device for recording or displaying information directly on an object, a device for reading information directly from an object, or a first device.
And apparatus for performing registration in a two-dimensional or three-dimensional space in a device or the like for transferring or displaying information on the object of the second object, particularly to a method of applying it to a semiconductor manufacturing device such as an X-ray aligner And equipment.

[Prior Art] Conventionally, this type of alignment method and apparatus includes a detection unit that measures the position of an object to be aligned, the amount of deviation of the object to a desired position, and the like, and a drive unit for the object. According to the measurement result by the means, the driving means moves the object for alignment.

In this case, the position of the object is represented in the coordinate system of the detection means which measures it, while the drive amount is represented in the coordinate system of the drive means. The detecting means and the driving means are arranged so that the coordinate system of the detecting means and the coordinate system of the driving means have a predetermined relationship. Therefore, the alignment of the object is calculated by calculating the driving amount of the driving unit from the displacement amount measured by the detecting unit using the relationship between these coordinate systems which is clear in advance, and moving the object by driving that amount. I was doing.

However, in actuality, when arranging the detection means and the driving means when assembling the device, there is a positioning error in these means, and due to fluctuations in the external environment such as vibration and heat,
The predetermined relationship between the detecting means and the driving means changes because of the displacement of the arrangement positions of the detecting means and the driving means. At this time, the driving amount is calculated and the driving unit is driven in the same manner as before according to the value measured by the detecting unit. That is, the predetermined relationship between the coordinate system of the detecting unit and the coordinate system of the driving unit, which is premised, is assumed. However, there is a drawback in that the alignment of the objects becomes poor. This is a serious problem particularly in an X-ray aligner or the like which requires high alignment accuracy.

[Object of the Invention] In view of the above-mentioned problems of the conventional type, an object of the present invention is to apply to a semiconductor manufacturing apparatus such as an X-ray aligner or the like to align an object such as a wafer with a predetermined position. That is, it is possible to perform highly accurate and efficient alignment without being affected by the fluctuation of. Further, according to the present invention, it is possible to associate each part of the independently configured alignment device with each other at the time of alignment, and it is possible to make the mounting precision of the parts at the time of manufacturing the device highly accurate. It is an object to provide an alignment method and device that are unnecessary.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the arrangement of an alignment apparatus according to an embodiment of the present invention. The apparatus shown in the figure is an alignment apparatus applied to a proximity X-ray aligner or the like.

In the figure, 1 is a fixed object, a mask made of glass or the like that transmits light, 2 is a wafer that reflects light, and the wafer is aligned with the mask 1 in a predetermined positional relationship, Denoted at 3 and 4 are detection devices for detecting relative displacement between the mask 1 and the wafer 2. This detection device is, for example, an alignment error (X, Y, θ) detection device as disclosed in Japanese Patent Laid-Open No. 59-99721.
Further, as a detection device using a television (TV), Japanese Patent Laid-Open No. 59-1
Devices such as those disclosed in 00527 can also be used. Reference numerals 5 and 6 are drive devices for moving the wafer 2 in two directions in the plane (XY plane), 7 is a drive device for rotating the wafer 2 in the plane, and 8 is an arithmetic unit for controlling the entire alignment operation. CPU for performing the above, 9 a memory such as RAM, ROM, 10 a keyboard, 11 an interface circuit between the arithmetic unit 8 and the detection units 3 and 4, 12 an interface circuit between the arithmetic unit 8 and the drive units 5, 6 and 7. , 13 are wafer holders that hold the wafer 2 and move in the XY plane.

The apparatus of this embodiment is an apparatus for transferring or displaying the pattern on the mask 1 onto the wafer 2, and the detecting apparatus 3 and the detecting apparatus using the alignment marks provided at each of two positions on the mask 1 and the wafer 2. The amount of displacement (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) in the two-dimensional direction at each location is measured by the procedure 4 and from this, the amount of displacement in the X direction X = (X ₁ + X ₂ ) / 2 …… (1) Y direction deviation amount Y = (Y ₁ + Y ₂ ) / 2 …… (2) θ direction deviation amount θ = (Y ₁ −Y ₂ ) / D D is a constant …… (3) This is a positioning device for moving the wafer 2 by driving the driving devices 5, 6 and 7 based on the obtained values.

Now, when the location measured by the detection devices 3 and 4 and the location when driven by the drive devices 5, 6 and 7 have a predetermined position or a predetermined positional relationship, that is, the coordinate system (X, Y, θ) and the coordinate system (X ′, Y ′,
When θ ′) has a predetermined relationship, the following relationship holds.

Here, x, y, and θ represent the amount of deviation of the wafer 2 from the desired position in the coordinate system of the detector. k ₁₁ ~ k ₃₃
Is a value that relates the detectors 3 and 4 to the drives 5, 6 and 7, that is, the coordinate system (X, Y, θ) in the detector and the coordinate system (X ′, Y ′, θ ′) in the drive. The relationship is shown, and when both are in a predetermined position or in a predetermined positional relationship, the values of k _{11 to} k ₃₃ are uniquely determined. Also, a, b, and c are the wafer 2 respectively.
The amount of driving the driving devices 5, 6 and 7 for the alignment of is represented by a coordinate system in the driving device.

From this relational expression (4), the driving amount of the driving devices 5, 6, 7 when the wafer 2 is moved to a predetermined position is obtained from the amount measured and calculated by the detecting devices 3, 4, and the position of the wafer 2 is calculated. Matching is possible.

However, in reality, in a step-and-repeat type semiconductor manufacturing apparatus or the like, the wafer 2 is moved. There is a positioning error of the detection device 3, the detection device 4, the driving device 5, and the driving device 6 when assembling the device. Due to changes in the positions of the detection device 3 and the detection device 4, the drive device 5, and the drive device 6 due to changes in the external environment such as heat, the predetermined positions between the detection devices 3 and 4 and the drive devices 5 and 6 are determined. Relationship changes. That is, at this time, since the predetermined relationship between the coordinate system in the detection device and the coordinate system in the drive device changes, the relationship between the displacement amount measured by the detection devices 3 and 4 and the amount driven by the drive devices 5 and 6 is shown ( 4) k ₁₁ to k in the formula
The value of ₃₃ changes and formula (4) no longer holds. For this reason, if the wafer 2 is moved according to the equation (4), there is a problem that the alignment becomes defective.

The alignment device of the present invention solves the above problems.

First, the principle of the present invention will be described with reference to the above embodiments.

In the present embodiment, the relationship between the coordinate system of the detecting means and the coordinate system of the driving means is obtained before performing the alignment, and the relational expression is used to enable highly accurate alignment. That is, k ₁₁ to k ₃₃ in the above relational expression (4) are obtained before alignment, and this value is used for alignment.

From equation (4), if this is transformed, However, The inverse matrix of And

That is, Is. From this, l _{11 to} l ₃₃ are one of a, b, and c
And other values are set to 0, for example, a = 1 and b = c = 0, and x, y, θ are obtained. In the above example, l ₁₁ = x, l
₂₁ = y, l ₃₁ = θ. In the following process, l ₁₁ to l ₃₃ are obtained based on this principle.

In the embodiment shown in FIG. 1, two detectors measure deviations in three directions (XYθ directions), and three driving devices are provided for the XYθ directions. Is composed of n detecting devices and n driving devices, the one corresponding to the equation (1) is Then, k _{11 to} knn can be obtained by the same method as described above, and the alignment can be performed. Where (x ₁ , x
₂ ..., xn) is the displacement of the object in the n-dimensional coordinate system measured by n detectors, and (a ₁ , a ₂ ..., an) is the object in the n-dimensional coordinate system of n driving devices. Is the driving amount.

The operation of the apparatus shown in FIG. 1 will be described below with reference to the flowchart shown in FIG.

In the figure, step S11 is a process for obtaining l ₁₁ to l ₃₃ ,
A step S12 obtains the k ₁₁ to k ₃₃ process, step S13 a,
The process of obtaining b and c, and step S14 is a process of performing alignment.

The positioning operation described below is performed by the CPU (arithmetic unit).
All are controlled and calculated by 8.

In FIG. 2, in step S11, first, the deviation amounts (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) of predetermined alignment marks (alignment marks) measured by the detection devices 3 and 4 are taken in, and CP
U8 is used in equations (1) to (3) to calculate each deviation amount of the wafer 2 in the XYθ directions with respect to the mask 1, and these values are calculated as x ₁ , y
_It is stored in the memory 9 as ₁ and θ ₁ . The alignment mark is attached to the mask 1 and the wafer 2 in advance. Next, the driving device 5 is driven by a unit amount while the driving devices 6 and 7 are stopped. At this time, the wafer 2 is determined from the alignment mark displacement amounts (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) measured by the detection devices 3 and 4.
Shift amounts x ₂ , y ₂ , θ ₂ of the mask 1 with respect to the mask 1 are calculated and stored in the memory 9. Next, x ₁ , y ₁ , θ ₁ in the memory 9
The difference between x ₂ , y ₂ , θ ₂ is calculated by using CPU 8 as l ₁₁ = x ₂ -x ₁ , l ₂₁ = y ₂ -y ₁ , l ₃₁ = θ ₂ -θ ₁
(8) is calculated and stored in the memory 9.

It should be noted that the unit amount here may be a predetermined amount, and may be any amount that can give a drive amount to the drive means with this amount as a reference.

Next, with the driving devices 5 and 7 stopped, the driving device 6 is driven by a unit amount, and the same process as above is performed to obtain the shift amounts x ₃ , y ₃ , θ ₃ .
l ₁₂ , l ₂₂ , l ₃₂ are calculated and stored in the memory 9.

Further, with the driving devices 5 and 6 stopped, the driving device 7 is driven by a unit amount, and the same processing as above is performed to obtain the shift amounts x ₄ , y ₄ and θ ₄ .
l ₁₃ , l ₂₃ , l ₃₃ are calculated and stored in the memory 9.

Through the above processing, l ₁₁ to l ₃₃ were obtained.

In step S12, by using l ₁₁ to l ₃₃ stored in the memory 9, the arithmetic unit (CPU) 8 calculates k ₁₁ to k ₃₃ from the equation (6).
Ask for. This is stored in the memory 9.

In step S13, the last measured displacement amount x ₄ , y ₄ , θ ₄
Is the deviation amount x, y, θ at the present time, so this value and k ₁₁ to k
_{Using 33} , the amounts a, b, c for driving the driving devices 5, 6, 7 for the alignment of the wafer 2 are obtained from the equation (4).

In step S14, the drive devices 5, 6, and 7 are controlled by the CPU 8 to control a, b, and c.
It is driven to move the wafer 2 to a predetermined position.

Positioning is performed by the above processing.

FIG. 3 shows a configuration of a positioning device obtained by partially modifying the embodiment of FIG. In the apparatus of FIG. 3, the same or common parts as those of the apparatus shown in FIG. 1 are designated by the same reference numerals.

Unlike the apparatus shown in FIG. 1, the apparatus shown in the figure aligns the wafer 2 in an apparatus which directly records or displays information on the wafer 2 without the mask 1 or reads information from the wafer 2. . Then, in this case, the wafer 2 is located at a predetermined position in space or the detection devices 3 and 4.
Are aligned in a predetermined relative positional relationship with respect to. This apparatus is a positioning apparatus applied in an exposure apparatus such as electron beam exposure.

In this modification, the alignment can be performed by the same operation as that of the above-described embodiment except that the detection devices 3 and 4 directly detect the position of the wafer 2.

These embodiments and modifications can be applied to a step-and-repeat type semiconductor manufacturing apparatus or the like, and a value relating the coordinate system can be obtained at each alignment stage. Also, during the first alignment operation of the day, the first operation of one lot, or the first operation after a large change in the environment, etc., the measured values of the detection device and the drive device It is also possible to obtain a value that correlates with the value to be moved.

For example, FIG. 4 is a flowchart showing an example of the alignment operation in the above-described embodiment and modification.

In the figure, in step S31, at the time of the first alignment operation of the day as described above, at the time of the first operation of one lot, or at the time of the first operation after a large change in environment etc.
An instruction from the keyboard 10 or a sensor for monitoring environmental changes and the like is given to the CPU 8 so as to obtain a related value at the time when a predetermined event occurs. Then, step S32
When alignment is started in step S33, first, in step S33, it is determined whether or not it is the time point instructed in step S31, that is, whether or not it is necessary to obtain a correlation value. If it is necessary, in step S34, the related value is obtained in the same manner as in steps S11 and S12 in FIG. 2 described above. Next, the value obtained in step S35 is stored in a predetermined location in the memory 9 so that it can be used in the subsequent processing. Memory 9 first
If this value is stored therein, the stored value will be corrected to the latest value.

In step S36, the associated value is read from the memory 9. Then, in steps S37 and S38, similarly to steps S13 and S14 in FIG. 2, the drive amounts of the drive devices 5 and 6 for moving are obtained, and the drive devices 5 and 6 are driven by the amount to drive the wafer 2 Align.

If it is determined in step S33 that it is not necessary to obtain the value to be associated, the alignment is performed in steps S36 to S38.

The above process is repeated as necessary when the wafer 2 is changed.

[Effects of the Invention] As described above, according to the present invention, the driving method is applied to the alignment method and apparatus that are applied to a semiconductor manufacturing apparatus such as an X-ray aligner and the like to align an object such as a wafer with a predetermined position. A predetermined amount of driving is performed to measure the amount of movement of the object, the relationship between the coordinate system in the detecting means and the coordinate system in the driving means is calculated from the measurement result, and alignment is performed based on the relationship. There is such an effect.

Even if there is a change in the predetermined positional relationship between the detecting means and the driving means, this positional relationship is calculated as necessary, so that highly accurate alignment is always possible.

Not affected by fluctuations due to external environment such as vibration and heat.

It enables efficient and especially time-efficient alignment.

Facilitates the manufacture of the device. In particular, a high placement position (alignment) accuracy is not required when attaching each part to the apparatus body.

It is possible to make mutual relations between the parts that are configured independently. Thus, the effects (1) to (3) can be obtained even for an independently configured device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an alignment apparatus according to an embodiment of the present invention, FIG. 2 is a flow chart for explaining a flow of alignment processing of the apparatus of FIG. 1, and FIG. FIG. 4 is a configuration diagram of a positioning device which is a modified example of the device shown in FIG. 4, and FIG. 4 is a flowchart showing an example of the positioning operation. 1: Mask, 2: Wafer, 3, 4: Detection device, 5, 6, 7: Drive device, 8: Arithmetic device (CPU), 9: Memory, 10: Keyboard.

Claims (5)

[Claims] 1. A method for measuring the position of an object by a detecting means, moving the object by a driving means on the basis of the measurement result, and aligning the object at a desired position. Driven, the amount of movement of the object at that time is measured by the detecting means, the relationship between the coordinate system in the detecting means and the coordinate system in the driving means is calculated from the measurement result, and the object is calculated based on the relationship. The positioning method is characterized in that the driving amount of the driving means is determined with respect to the positional deviation amount, and the object is positioned. 2. A detecting means for measuring the position of an object, a driving means for moving the object, and a predetermined amount of driving of the driving means before the positioning of the object. Control means for measuring by the detecting means, first calculating means for calculating the relation between the coordinate system in the detecting means and the coordinate system in the driving means from the measurement result, and from the desired position of the object based on the relation Second computing means for calculating the driving amount of the driving means corresponding to the shift amount of the object, and moving the object by using the driving amount calculated by the second computing means to align the object at a desired position. An alignment device characterized by: 3. The object is a semiconductor wafer which projects a pattern drawn on a mask, and the detection means measures a relative positional relationship between the mask and the semiconductor wafer. The alignment device according to item 2. 4. The alignment apparatus according to claim 2, wherein the object is a semiconductor wafer, and the detecting means measures the relative position of the semiconductor wafer with respect to a predetermined reference position. 5. The alignment device according to claim 3 or 4, wherein the calculation of the relationship in said calculating means is performed at the time when a predetermined event occurs.