JPS608724B2 - detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device that detects the position, size, etc. of a linear or dotted pattern.

Conventionally, devices for detecting linear patterns scan the optical image of the linear pattern using vibration of a slit or rotation of a mirror, convert it into a video signal with a light receiving element, and detect the linear pattern. An optical scanning method that detects the position of a pattern is known.

However, the vibration of the slit and the rotation of the mirror must be mechanically driven, making it expensive, generating vibrations, etc., making it difficult to detect with high precision, and furthermore, since it has a mechanical drive part. It had the drawback of poor reliability.

An object of the present invention is to provide a detection device that eliminates the above-mentioned conventional drawbacks and is capable of detecting the position or size of a pattern based on photosensitivity using a -dimensional solid-state image sensor in which photoelectric conversion elements are arranged. There is something to do.

That is, in order to achieve the above object, the present invention provides a one-dimensional solid-state image sensor in which photoelectric conversion elements are arranged, and converts light from a direction perpendicular to the arrangement direction of the one-dimensional solid-state image sensor into the one-dimensional solid-state image sensor. This detection device is characterized in that it is equipped with a condensing optical system that condenses light onto an element, and is configured to detect a linear or dot array pattern with high sensitivity. Further, the present invention is characterized in that the condensing optical system of the detection device is constituted by a cylindrical lens. The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 1 shows a mask as an example of an object to be detected, and FIG. 2 shows a semiconductor wafer as another example of an object to be detected. The mask shown in the figure includes two first identification patterns at both ends for alignment with the circuit pattern 2 to be exposed and printed at a predetermined position 4 of the semiconductor wafer 6 and the semiconductor wafer 6, and a linear pattern. With this, target patterns 3a and 3b for position alignment are formed. On the other hand, on the semiconductor wafer 6, two second
The identification pattern is a linear pattern, and also forms the target patterns 5a and 5b for position matching.
Target patterns 3a, 3 for positional alignment of the mask
b is formed in a linear pattern, for example, as shown in Fig. 1, L-shaped opaque lines are arranged in a cross shape in a transparent area to form a transparent band having a constant center in the shape of a cross. There is. This transparent band is an identification area, and one end of each band is the starting end and the other end is the ending end. Further, as the target patterns 5a and 5b for position alignment of the semiconductor wafer,
It is also formed as a linear pattern, for example, as shown in FIG. 2, there is a pattern formed of cross-shaped thin lines having a different reflectance from the surrounding area. Next, we will discuss the third aspect of the mask position alignment device of the present invention.
This will be explained based on FIGS. 6 to 6. 7 is a rotating table, and a semiconductor wafer 6 is sent to it.

Reference numeral 8 denotes an X-axis moving table, rotatably supporting the rotary table 7, and a motor 9 for rotating the rotary table 7 is attached. A Y-koji moving table is used, and the x-axis moving table 8 is slidably mounted on the x-axis in all directions, and an X-axis motor 1 is attached to move the x-axis moving table 8 in the x-ball direction.

Furthermore, the Y-axis drive table 10 is mounted on a base (not shown).
The Y is remounted so that it can slide freely in the axial direction and is moved in the Y-axis direction.
It is connected to the shaft motor 12. On the other hand, the mask is placed at a very small distance from the semiconductor wafer 9, and is placed on the base (
(not shown) attached to a retaining member (not shown). Optical systems 13a and 13b are provided facing the position matching targets 3a and 3b, respectively, and are constructed as shown in FIG.

That is, the optical systems 13a and 13b include an objective lens 14 that magnifies the optical image of the superimposed target pattern for positional alignment;
A semi-transparent mirror 15, a condenser lens 16, a light source 17, a semi-transparent mirror 18, and a cylindrical lens 20, which is arranged with its center in the vertical direction and reduces the light image reflected by the semi-transparent mirror 18 in the X-axis direction. , and a cylindrical lens 21 whose axial center direction is arranged in the X-axis direction and which constricts the optical image passing through the semi-transparent mirror 18 in the Y-axis direction. That is, the semi-transparent mirror 18 and the cylindrical lens 2
0 is arranged so that the Y component of the optical image magnified by the objective lens 14 is directly projected in the vertical direction of the photodiode arrays 22a, 22b, and the X component is reduced and projected into the photodiode arrays 22a, 22b. There is.
Furthermore, the semi-transparent mirror 18 and the cylindrical lens 21 project the X component of the enlarged optical image as it is in the It is arranged so that it is projected inside. 22a and 22b are Y-axis photodiode arrays in which a large number of photodiode elements are arranged in a line, and the longitudinal direction is arranged in the direction of the cylindrical lens 20, and the photodiode arrays 22a and 22b receive the light beams that have passed through the cylindrical lens 20 and generate scan signals. Electrical signals are output in series from each photodiode element in response to the current.

23a and 23b are photodiode arrays in which a large number of photodiode elements are arranged in rows, the longitudinal direction of which is arranged in the axial direction of the cylindrical lens 21, and the light image passing through the cylindrical lens 21 is The device receives light and outputs an electrical signal in series from each photodiode element in response to a scan signal.

Reference numeral 24 designates a scan signal generation circuit, and outputs scan signals 25a and 25b from the photodiode array 22.
a, 22b and photodiode arrays 23a, 23b.

28a is a processing circuit, and a photodiode array 22a
As shown in FIG. 5, the reference distance Δ in the Y-axis direction between the position alignment target 3a on the mask 1 and the position alignment target 5a on the semiconductor wafer 6 is determined by the signal 26a output from the
This is a circuit to find the deviation Δy with respect to 2.

28b is a processing circuit which uses a signal 26b outputted from the photodiode array 22b to detect the Y of the position matching target 3b and the position matching target 5b as shown in FIG.
This circuit calculates the deviation Δy2 with respect to the reference distance Δ2 in the axial direction.

29a is a processing circuit, and a signal 27a output from the photodiode array 23a is used to detect the deviation from the reference distance Δ in the X-axis direction between the position matching target 3a and the position matching target 5a, as shown in FIG. This is a circuit to find △×.

29b is a processing circuit which uses a signal 27b outputted from the photodiode array 23b to determine the reference distance Δ in the X-axis direction between the position matching target 3b and the position matching target 5b as shown in FIG. This circuit calculates the deviation Δ×2 for

In the three-way calculation circuit, the signal △y outputted from the processing circuit 28a and the signal △y2 outputted from the processing circuit 28b.
Arithmetic processing is performed based on the signal , the signal △x, output from the processing circuit 29a, and the signal Δx output from the processing circuit 29b, and the
Relative displacement amount △× in the koji direction, mask 1 and semiconductor wafer 6
This circuit calculates the relative displacement amount Δy in the Y-axis direction, and the relative displacement amount A■ in the rotational direction of the mask 1 and the semiconductor wafer 6 about the rotation axis of the rotary table 7.

31 is a drive circuit, and △ is output from the arithmetic circuit 30.
The X-axis motor 11 is driven until the × signal becomes zero, the Y-axis motor 12 is driven until the △y signal output from the arithmetic circuit 30 becomes zero, and the △■ signal output from the arithmetic circuit 30 is
The motor 9 is driven until the signal becomes zero.

With the above configuration, first the semiconductor wafer 6 is placed on the rotary table 6, and when the mask 1 is placed on a holding member (not shown), the target pattern 5a for position alignment of the semiconductor wafer 6,
5b and the target pattern 3a for positional alignment of the mask 1,
3b are arranged in an overlapping manner as shown in FIGS. 5a and 5b.
Next, when the light source 17 is turned on, the light emitted from the light source 17 is converted into parallel light by the condenser lens 16,
Position alignment target patterns 3a, 5a and 3b reflected by the semi-transparent mirror 15 and superimposed through the objective lens 14
, 5b. Position matching target pattern 5a
The light reflected from the position matching target pattern 3a
It passes through the transparent area and is formed as a light ridge. This optical image is magnified by the objective lens 14, passes through the semi-transparent mirror 15, and reaches the semi-transparent mirror 18. The light image reflected by the inner semi-transparent mirror 18 is formed into stripes by the cylindrical lens 20 in the x-axis direction from WX to the middle dimension LX of the photodiode array 22a as shown in FIG. The light image formed on the light-receiving surface of the array 22a and passed through the semi-transparent mirror is transmitted by the cylindrical lens 21 in the Y-axis direction from WY to the middle dimension LY of the photodiode array 23a, as shown in FIG. The light is focused on the light receiving surface of the photodiode array 23a. Target pattern 5 for position alignment on the other hand
The light reflected from b is the target pattern 3 for position alignment.
From b, the light passes through the transparent area and is formed as an optical image. This light image reaches the semi-transparent mirror 18 in the same way as before, and the semi-transparent mirror 18
The light image reflected by the photodiode array 22b is formed on the light receiving surface of the photodiode array 22b, and the light image that has passed through the semi-transparent mirror 18 is formed on the light receiving surface of the photodiode array 23b. That is, the photodiode elements of the photodiode arrays 22a, 23a and 22b, 23b convert the superimposed alignment patterns 5a, 3a and 5b, 3b into X-ray images magnified by the objective lens 14, as shown in FIG. An image is received of a picture element detection region divided at regular intervals of the photodiode element in the axial direction, and an image is further received of a picture element detection region divided at regular intervals of the photodiode element in the Y-axis direction. Next, the photodiode arrays 22a and 22b are each scanned in the scan direction shown in FIG. 6 by the scan signal output from the scan signal generation circuit 24, and the photodiode arrays 22a and 22b receive the signals output from the photodiode elements as shown in FIG. Signal 26 in the shape of a bowed
a, 26b are output. The processing circuits 28a and 28b perform bit processing on the signals 26a and 26D, respectively, to determine the distance ya,, momme 2 between the first peak value and the second peak value.
, that is, the time t,,tya2 and the distances yb, yb2 between the second peak value and the third peak value, that is, the time difference q, tyb2, are calculated from the following equations [1' and 2]. Find the deviation △y,, △average. △y,=△h. (txb,
Ittya,)=K. (tyb, -tya,)……………
[1'k・△t△y2=△h. (tyb2-tya2)
=K. (tyb2-tya2)………'21k・△
t However, △h: Distance between diode elements (bits) △t: Time required to scan adjacent diode elements k: Image magnification rate by objective lens 14 K: K = time and displacement determined from Sansei 7 Similarly to the conversion constant, the photodiode arrays 23a and 23b are also scanned,
As shown in FIG. 6, signals 27a and 27b are output which are different from the signals output from the photodiode element.

The processing circuits 29a and 29b receive the signals 26a and 26b, respectively.
By bit processing, we obtain the distance between the first peak value and the second peak value, , xa2, that is, the time txa,, t, and the second peak value and the third peak value. Find the distance cutting, , cutting 2, that is, the time cutting, txQ, and calculate the deviation △×. , △average. △X
,=△h. (tyo, -txa,)=K. (t-kari, one-tx
a,)…………[3}k・△tA average=△h. (t mowing 2
-txa2)=K. (t-kari 2-tx also)……………[4
) k・△t Note that, as shown in FIG.
Addresses in the center of mountains 6a, 26b, and 27a, 27b,
Alternatively, the address indicating the peak value may be set as the center position of the position matching target patterns 5a, 5b.

Furthermore, the exercise circuit 30 performs the following calculation based on the signals △×, △×2, △y・, △y2 obtained by the processing circuit, and calculates the relative displacement amount △ between the mask and the semiconductor wafer 6. Find ×, △y, △@. That is, as shown in FIG. 7, the mask 1 is rotated around the rotation axis p of the rotary table 7.
The relative displacement amount Δ■ in the rotational direction between the position alignment target patterns 3a, 3b and the position alignment target patterns 5a, 5b of the semiconductor wafer 6 has the following relationship. 1LSin△■=-(△y, 1△y2)…………
■From the relationship of the above equation (■), we have the relationship of the following equation (■).

．．・．． △■≠1/L(△y, -△y2)=8. (△y,
- △y2) ......................{6- However, L is the distance between the centers of the target patterns 5a and 5b for position matching, and ■o
is a constant corresponding to the value 1/L. Note that △■ is △y
, , .DELTA.y2 because two positional alignment target patterns 5a and 5b are arranged in the X-axis direction. Further, the relative displacement amount Δx in the X-axis direction between the position alignment target patterns 3a, 3b of the mask 1 and the position alignment target patterns 5a, 5b of the semiconductor wafer 6 is as follows.
It has the following equation (7) and shelf equation relationship. △×i△×
, 1△Q, △×d△&10△o ………(7)＾△X=
Season (△~10△cedar)………………■Also, the relative displacement amount △y in the Y-axis direction between the position matching target patterns 3a, 3b of the mask and the position matching target patterns 5a, 5b of the semiconductor substrate 6 has the following relationship of the ■ type and the plate type.

△y=△y, ten△8 “△y=△y2−△8 ………
[9}.・．． △y=1/2 (△y, ten △y2)
……………{10th △×, △y obtained as above
, Δ■ are transmitted to the drive circuit 31.

The drive circuit 31 only calculates the determined values of △×, △y, △@,
Drive the X-axis motor 11, Y-axis motor 12, and motor 9 in the opposite direction, and when the above △x, △y, and △■ all become zero, the mask turtle and the semiconductor wafer 6 are precisely aligned. be done.
As the photodiode array, there is already one in which 1024 photodiode elements are arranged in a line and has a length on the 25.4 side.

Further, the target pattern for position alignment is formed at one or two side corners. Therefore, even if the entire surface of the target pattern for position alignment is imaged by the photodiode array, the positioning accuracy between the mask and the semiconductor wafer can be obtained on the order of 1 to 2 degrees. In the above embodiment, two photodiode arrays in which photodiode elements are arranged in a row are used as optical image detection elements.
The semi-transparent mirror 18 of the optical system 13a, 13b is used.
If the cylindrical lenses 20 and 21 are removed and a photodiode matrix in which photodiode elements for receiving images of silk-like picture elements, that is, detection areas are arranged vertically and horizontally in a two-dimensional plane, is placed at the positions of the photodiode arrays 23a and 23b, the above-mentioned result can be obtained. The same effects as the embodiment can be achieved.

Note that when using a photodiode matrix, when determining the relative displacement between the position matching target patterns 5a, 5b in the X-axis direction and the position matching target patterns 3a, 3b, the diode elements arranged in the Y-axis direction are used. The diode elements arranged in the X-axis direction are used to simultaneously scan and electrically integrate the signals and to obtain the relative displacement between the position matching target patterns 5a, 5b in the Y-axis direction and the position matching target patterns 3a, 3b. If the signals are scanned and electrically integrated at the same time, an effect similar to that of the cylindrical lens of the above embodiment in which the optical image is contracted in the middle direction can be obtained. Further, in the above embodiment, the target pattern for position alignment of the mask is formed of a cross-shaped transparent band made of a linear pattern, and the target pattern is formed of a thin green cross made of a linear pattern having a reflectance different from that of the surrounding area. This is a superimposed pattern with the target pattern for position alignment of Waha, but in addition, for example, Figs.
A transparent or opaque [shaped, L-shaped linear pattern or...
A target pattern for mask alignment formed by a dot array pattern surrounded by marks or a linear square transparent pattern, etc., and the surroundings and reflectance or transmittance as shown in FIGS. 9a to 9c. Rates are different.

・Even if the target pattern for positioning the semiconductor wafer formed of marks, squares, cross bands, etc. is aligned and superimposed, the same effect as in the above embodiment can be achieved, so the target pattern for positioning is Various shapes can be selected, and the shape is not limited to the above embodiment. Furthermore, in the above embodiments, the x and y directions are orthogonal, but are not necessarily limited to orthogonal coordinates. As explained above, the present invention uses a one-dimensional collective image sensor in which photoelectric transducers (photosensitive elements) without moving parts are arranged in a line, and a pattern imaged by a condensing optical system such as a cylindrical lens. As stated above, since this is a detection device that optically compresses and focuses light in the direction perpendicular to the arrangement direction of the one-dimensional solid-state image sensor, it can detect linear patterns or dot array patterns with high sensitivity even with a simple configuration. This has the effect that the shape or size of the pattern can be detected with high precision.

In particular, even if the linear pattern or dot array pattern is partially deformed or has foreign matter attached to it, or even if the contrast of the pattern is poor, it can be detected with high accuracy. .

[Brief explanation of the drawing]

Figure 1 shows a mask as an example of the object to be detected, Figure 2 shows a mask as an example of the object to be detected.
The figure shows a semi-transparent wafer which is an example of an object to be detected, FIG. 3 is a schematic configuration diagram showing a mask position alignment device which is an embodiment of the position detection device of the present invention, and FIG. FIG. 3 is a diagram showing details of the optical system shown in FIG. Figure 3 shows the optical image received by the photodiode array and the signal waveform obtained from the photodiode array, and Figure 7 shows the target pattern for mask alignment and the semiconductor wafer. Figure 8 shows an example of a target pattern for aligning a mask, and Figure 9 shows an example of a target pattern for aligning a semiconductor wafer. FIG. 1... Mask, 3a, 3b... Target pattern for position alignment, 5a, 5b... Target pattern for position alignment, 6... Semiconductor wafer,
13a, 13b...optical system, 14...
Objective lens, 17...Light source, 18...
Semi-transparent mirror, 20, 21...Cylindrical lens, 22a, 22b, 23a, 23b...Photodiode array, 24...Scan signal generation circuit, 28a, 2
8b, 29a, 29b...processing circuit, 29...
... Arithmetic circuit, 30... Drive circuit. O / 4 O Figure 2 O Figure 3 O 4 Meat Guzu Figure Off figure Figure 8 Galley diagram

Claims (1)

[Scope of Claims] 1. A condensing optical system that condenses a light image from an object to be detected having a linear or dot array pattern in the direction in which the pattern extends; and a one-dimensional solid-state image sensor that receives an image of the pattern, and has photoelectric conversion elements arranged in a direction perpendicular to the direction in which the pattern extends, and a one-dimensional solid-state image sensor that receives a photoelectric conversion element that corresponds to each photoelectric conversion element of the one-dimensional solid-state image sensor. A detection device characterized in that the position of the pattern is detected based on a video signal obtained by 2. The detection device according to claim 1, wherein the condensing optical system is a cylindrical lens.