JPH07113528B2 - 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 method for aligning the gap between objects in a device for transferring or displaying the information on the object to the second object, etc., and particularly a position applied to a semiconductor manufacturing apparatus such as a step-and-repeat type X-ray aligner A matching method and apparatus.

[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.

However, in practice, as in the step-and-repeat type semiconductor manufacturing apparatus or the like, the position of the object for alignment is detected at several places, so the object may be moved each time. In this case, the detection point on the object for detecting the positional deviation by the detection means and the point of action on which the driving means acts when moving the object must be separate locations, and the positional relationship between the detection point and the point of action is different. Changes with the movement of the object, so the positional relationship between the detection means and the drive means also changes.

If the position detection point and the object movement action point coincide with each other, the drive amount may be calculated corresponding to the detected shift amount, and the drive amount may be driven. However, in the case where the detection point and the action point are different places as described above, the drive amount of the drive means is calculated and driven by a predetermined method based on the value measured by the detection means. Since the positional relationship between the detecting means and the driving means has changed, accurate positioning cannot be performed. 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 a step-and-repeat type X-ray aligner or the like, and a method for aligning an object such as a wafer with a predetermined position. The object of the present invention is to enable highly accurate alignment even in the case where the positional relationship between the detecting means for measuring the position of the object and the driving means for moving the object changes.

[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 a positioning apparatus applied to a step-and-repeat type 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 semiconductor wafer that is made of a material that reflects light, and is aligned with the mask 1 at a predetermined distance. And 4 are gap detection devices (sensors) for measuring the distances g ₁ and g ₂ between the mask 1 and the wafer 2, respectively. The gap detecting devices 3 and 4 are, for example, the devices disclosed in JP-A-56-130922. Reference numerals 5 and 6 respectively denote a drive unit having a piezo stack or a piezo drive circuit for moving the wafer 2 in the Z-axis direction, and 7 an arithmetic unit that is a CPU that controls the entire alignment operation.
8 is a memory such as RAM and ROM, 9 is a keyboard, 10 is an interface circuit connecting the CPU 7 and the detection devices 3 and 4, 11 is a CPU
It is an interface circuit that connects 7 and Z drive devices 5 and 6. Further, 12 is a mask holder for fixing the mask 1, and 13 is a wafer holder which moves integrally with the Z drive devices 5 and 6 on the XY plane. a and b are position detection points on the wafer 2 of the gap detection devices 3 and 4, and c and d are action points on which the drive devices 5 and 6 act. This device moves the wafer 2 in the Z-axis direction by the driving devices 5 and 6 based on the distances g ₁ and g ₂ between the mask 1 and the wafer 2 measured by the detection devices 3 and 4, and the wafer 2 is masked. The position is adjusted to a predetermined position with respect to 1.

In this embodiment, the pattern on the object 1 is generally used as the object 2
It can also be applied to a device for transferring or displaying the image on the top, or a device for photographing the pattern on the object 2 with the object 1.

The operation of the apparatus of this embodiment will be described below.

Now, the detection points a and b measured by the detection device 3 and the detection device 4 and the action points c and d when driven by the drive device 5 and the drive device 6
However, if they are in a predetermined position or in a predetermined positional relationship, for example, they match, the relationship of the following expression (1) is established.

Here, h ₁ and h ₂ are amounts for driving the driving devices 5 and 6 for aligning the wafer 2, respectively. k _{11 to} k ₂₂ are values that relate the detection devices 3 and 4 to the drive devices 5 and 6, and
It is uniquely determined when the 3, 4 and the driving devices 5, 6 are in a predetermined position or in a predetermined positional relationship. Further, g ₁ ′ and g ₂ ′ are the deviation amounts of the wafer 2 from the desired position, that is, the detection devices 3,
This is the distance moved to align the wafer 2 with the mask 1 based on the distance measured in 4.

From the relationship of this equation (1), the drive amount of the drive devices 5 and 6 when the wafer 2 is moved to a desired position is obtained from the distance measured by the detection devices 3 and 4, and the mask 1 and the wafer 2 are separated. Positioning is possible. Therefore, if, for example, the detection point a of the position and the action point c of the drive device are at the same position, and the detection point b and the action point d are at the same position, then equation (1)
It becomes possible to align using.

However, in practice, as in a step-and-repeat type semiconductor manufacturing apparatus that moves the wafer in steps to detect the position, the detection point for detecting the positional deviation and the action point for moving the wafer have to be separated from each other. I don't get. For example, as shown in FIG. 1, the detection point a and the action point c are separated by a distance.
x ₁ , the detection point b and the action point d are separated by a distance x ₂ . Therefore, the predetermined relationship between the detection devices 3 and 4 and the drive devices 5 and 6 changes. That is, at this time, the values of k ₁₁ to k _{22 in} the equation (1) showing the relationship between the displacement amount calculated from the value of the distance measured by the detection devices 3 and 4 and the amount driven by the drive devices 5 and 6 are However, the equation (1) will not hold. Therefore, (1)
If the wafer 2 is moved according to the formula, 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 this embodiment, the relationship between the detecting means and the driving means is obtained immediately before performing the alignment for each step, and the highly accurate alignment is possible. That is, k ₁₁ to k ₂₂ in the above relational expression (1) are obtained before alignment and alignment is performed using this value.

From equation (1), if this is transformed, here, Becomes

In equation (2), if h ₁ = 1 and h ₂ = 0 If h ₁ = 0 and h ₂ = 1 Becomes Therefore, from the equations (5) and (6), from the measured values of the detection device 3 and the detection device 4 when the drive device 5 is driven by a unit amount while the drive device 6 is stopped, l ₁₁ and l
You can ask for ₂₁ . Similarly, l ₁₂ and l ₂₂ can be obtained from the measured values when the driving device 5 is stopped and the driving device 6 is driven by a unit amount. Here, the unit amount 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. Using l ₁₁ to l ₂₂ obtained as described above, k ₁₁ to k ₂₂ from (4)
Ask for. This allows alignment.

Next, with reference to the flowchart of FIG. 2, the flow of the alignment process of the apparatus of FIG. 1 will be described.

In the figure, step S1 is a process for obtaining l ₁₁ to l ₂₂ , step S2 is a process for obtaining k ₁₁ to k ₂₂ , and step S3 is g ₁ ′.
a process for obtaining g ₂ ′, step S4 is a process for obtaining h ₁ and h ₂ ,
Step S5 is a process for performing alignment.

The processing flow described below is based on the CPU (arithmetic unit) 7
Controlled and calculated by.

In step S1, first, the distance between the mask 1 and the wafer 2 is measured by the detection devices 3 and 4, and the interface circuit 10
To the memory 8 through. This measurement is g ₁₁ and g
₂₁ . Next, through the interface circuit 11, CP
The drive device 5 is driven by a unit amount under the control of U7. At this time, the drive device 6 is stopped. Next, the CPU 7 measures the distance between the mask 1 and the wafer 2 after driving with the detectors 3 and 4, and obtains this measured value through the interface circuit 10.
It is stored in the memory 8. This measurement and g ₁₂ and g _23. Next, the differences l ₁₁ = g ₁₂ −g ₁₁ , l ₂₁ = g ₂₂ −g ₂₁ between g ₁₂ and g ₂₂ and g ₁₁ and g ₁₂ stored in the memory 8 are calculated, and Store in 8.

Next, similarly to the above, only the drive device 6 is driven by a unit amount,
The values g ₁₃ and g ₂₃ measured by the detection devices 3 and 4 at this time are stored in the memory 8. And g ₁₃ and g ₂₃ in the memory 8
And the difference between each of g ₁₂ and g ₂₂ l ₁₂ = g ₁₃ −g ₁₂ , l ₂₂ = g ₂₃ −g ₂₂ (8) is calculated and stored in the memory 8. By the above processing, l
_{11 to} l ₂₂ can be obtained. This is stored in the memory 8.

In step S2, the arithmetic unit (CPU) 7 calculates l ₁₁ obtained earlier.
Using to l _22, obtains the k ₁₁ to k ₂₂ from (4). This value gives the relationship between the measured values of the detection devices 3 and 4 and the amount of movement of the wafer 2 by the drive devices 5 and 6.

In step S3, as seen from the positions of the detection devices 3 and 4,
Deviation amount g ₁ ′ from a predetermined position g _{0 for} aligning the wafer 2
And g ₂ ′. That is, the values of g ₁₃ and g ₂₃ , which are the distances between the mask 1 and the wafer 2 at the present time, are taken out from the memory 8 and the difference from g ₀ is g ₁ ′ = g ₁₃ −g ₀ , g ₂ ′ = g ₂₃ − g ₀ (9) is calculated and stored in the memory 8.

K ₁₁ to k ₂₂ of step S4 in the memory 8, g ₁ 'and g _2'
From the above, the driving amounts h ₁ and h ₂ of the driving devices 5 and 6 for moving the wafer 2 are obtained using the equation (1). This is stored in the memory 8.

In step S5, the CPU 7 controls the driving devices 5 and 6 through the interface circuit 11 to drive the driving devices 5 and 6 by the values of h ₁ and h ₂ in the memory 8 to move the wafer 2 for alignment.

The alignment is executed as described above, after the exposure is performed at the position, the process moves in steps and the alignment process is performed again from step S1.

FIG. 3 shows a map of the memory 8. The memory 8 is a RAM or a ROM, and each value of g _{11 to} h ₂ is stored in a predetermined address in the memory 8.

In the embodiment shown in FIG. 1, two detection devices are provided for simplicity.
Although the case where the number of driving devices is two is shown, generally, three or more detecting devices and three or more driving devices are required to align the gap between the flat plates. Further, in the case of n detection devices and n drive devices, the one corresponding to the equation (1) is Then, k ₁₁ to k _nn can be obtained by the same method as described above, and the alignment can be performed.

FIG. 4 shows the structure of a positioning device obtained by partially modifying the embodiment of FIG. In FIG. 4, the same or common parts as those of the device of 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, alignment can be performed by the same operation as that of the embodiment of FIG. 1 except that the detection devices 3 and 4 measure the distance from a predetermined position to the wafer 2.
Further, when the number of detecting devices and the number of driving devices are each three or more, the formula (10) is established, and the alignment can be performed by the same method as described above.

[Effects of the Invention] As described above, according to the present invention, each driving means is applied to a step-and-repeat type semiconductor manufacturing apparatus or the like and in a positioning method and apparatus for positioning an object such as a wafer at a predetermined position. Each time it is driven by a predetermined amount to measure the amount of movement of the object, the relationship between the detection means and each driving means is calculated from the measurement result, and the alignment is performed based on that relationship, so the following effects There is.

Even if the detection point of the detection means and the action point of the drive means are different, since the relationship between the detection means and each drive means is obtained, highly accurate alignment is always possible.

Even if the relationship between the detecting means and the driving means changes due to external environment such as vibration or heat, the influence can be reduced and alignment can be performed.

It enables efficient and especially time-efficient alignment.

Facilitates the manufacture of the device. Especially when mounting each part to the main body of the apparatus, a high placement position (alignment) precision is not required.

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. A memory map in the apparatus shown in FIG. 4, and FIG. 4 is a configuration diagram of an alignment apparatus which is a modification of the apparatus shown in FIG. 1: Mask, 2: Wafer, 3, 4: Gap detection device, 5, 6: Z drive device, 7: Arithmetic device (CPU), 8: Memory, 9: Keyboard.

Claims (4)

[Claims] 1. A plurality of detection means for detecting the position of an object at a plurality of predetermined detection points on the object, and a plurality of detection points on the object which are defined separately from the detection points based on the measurement results. In a method of aligning the object to a desired position by a plurality of driving means that act on an action point and move the object, one of the plurality of driving means is driven by a predetermined amount and another driving means is driven. Measuring the amount of movement of the object when the object is stopped by the plurality of detecting means, and calculating the relationship between the amount of movement of the driven driving means and the amount of movement of the object based on the measurement results; Based on the calculated relationship between the driving amount of each driving unit and the moving amount of the object, the step of changing the driving unit in sequence to perform the above steps, and the displacement of the object from the desired position Determine the drive amount of the drive means That step and, alignment method characterized by comprising the step of performing the alignment of the object by driving the respective drive means in response to the driving amount of each drive means are determined. 2. A plurality of detection means for detecting the position of an object at a plurality of predetermined detection points on the object, and a plurality of action points on the object which are defined separately from the detection points and act on the plurality of action points. A plurality of drive means for moving the object, and one of the plurality of drive means is driven by a predetermined amount in a state in which the other drive means is stopped, and the movement amount of the object at that time is the plurality of Measured by the detection means of
From the measurement result, the relationship between the driving amount of the driven driving unit and the moving amount of the object is calculated and stored, and further, the driving unit that drives the series of operations of driving, measurement, calculation and storage is performed. Based on the relationship between the stored driving amount of each driving unit and the moving amount of the object, the driving amount of each driving unit with respect to the positional deviation amount from the alignment target position of the object is sequentially changed. A positioning device having a control means for determining. 3. The object according to claim 2, wherein the object is a semiconductor wafer for projecting a pattern drawn on a mask, and the detecting means measures a relative distance between the mask and the semiconductor wafer. The alignment device described. 4. The alignment apparatus according to claim 2, wherein the object is a semiconductor wafer, and the detecting means measures a distance from a predetermined reference position to the semiconductor wafer.