JP2022092255A - Pattern position measuring device - Google Patents

Abstract

To provide a pattern position measuring device that can maintain measurement precision and can perform measurement rapidly when measuring a position of a measurement object pattern formed in a measurement object work.SOLUTION: A pattern position measuring device for measuring a relative position between a first measurement object pattern formed in a first measurement object work and a second measurement object pattern formed in a second measurement object work includes a work holding part, an imaging part, and a pattern position deviation amount measurement part. The imaging part includes an optical path branching part, a first imaging part, and a second imaging part, the first imaging part captures an image by focusing on a surface in which the first measurement object pattern of the first measurement object work is formed, and the second imaging part captures an image by focusing on a surface in which the second measurement object pattern of the second measurement object work is formed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pattern position measuring device for measuring the position of a measurement target pattern formed on a measurement target work. In particular, the present invention relates to an apparatus for superimposing two substrates and measuring the relative positions of measurement target patterns formed on the surface or inner surface of each substrate.

A semiconductor device is formed by forming a large number of semiconductor device circuits (that is, repeated appearance patterns of device chips) on one semiconductor wafer, and then individualized into individual chip components, and the chip components are packaged. , Shipped individually as electronic components or incorporated into electrical products.

Then, in the semiconductor device circuit, a pattern of a plurality of layers is formed on the semiconductor wafer, and after the upper layer pattern is formed, the superposition accuracy and the error with the lower layer pattern are measured (that is, the pattern position measurement). (For example, Patent Document 1).

Then, even if the layers to be observed are separated from each other, a technique for simultaneously observing objects at at least two different focal positions on the same optical axis on one image plane has been proposed (for example, Patent Document). 2).

Japanese Patent Application Laid-Open No. 2003-254715 Japanese Unexamined Patent Publication No. 7-270716

When the focus positions of the work to be measured and the reference work are different, in the technique disclosed in Patent Document 1, the focus position is first focused on one work to acquire an image, and then the focus position is changed to the other work. Since the image is acquired, the time spent on the measurement is extended. Further, if the focus adjustment direction is deviated from the image pickup optical axis, the accuracy of position measurement is lowered. Alternatively, there is a risk of misalignment during focus adjustment.

On the other hand, in the technique disclosed in Patent Document 2, the other pattern is reflected in one pattern image, and there is a possibility that the measurement target pattern is erroneously detected.

Further, in order to solve these problems, two superposed substrates are imaged using an optical system independent from different directions (the upper substrate is looked down from the upper side, and the lower substrate is looked up from the lower side). ) There is also a method, but it is not realistic because it may be overlooked even if the imaging optical axis shifts over time and the position cannot be measured with the desired accuracy.

Therefore, the present invention has been made in view of the above problems.
It is an object of the present invention to provide a pattern position measuring device capable of rapid measurement while maintaining measurement accuracy when measuring the position of a measurement target pattern formed on a measurement target work.

In order to solve the above problems, one aspect of the present invention is
A pattern position measuring device that measures the relative position between the first measurement target pattern formed on the first measurement target work and the second measurement target pattern formed on the second measurement target work.
With the work holding unit that holds the first measurement target work and the second measurement target work so that the first measurement target pattern and the second measurement target pattern that are in a corresponding relationship in the relative position measurement maintain a predetermined positional relationship. ,
An imaging unit that captures the first measurement target pattern and the second measurement target pattern,
It is equipped with a pattern position deviation amount measuring unit that measures the deviation amount between the first measurement target pattern and the second measurement target pattern.
The image pickup unit
An optical path branching portion that branches the imaging optical path into the first optical path and the second optical path while sharing the optical axis with respect to the imaging region.
A first imaging unit that captures an imaging region via the first optical path,
It is equipped with a second imaging unit that images the imaging area via the second optical path.
The first image pickup unit focuses on the surface of the first measurement target work on which the first measurement target pattern is formed, and takes an image.
The second image pickup unit focuses on the surface of the second measurement target work on which the second measurement target pattern is formed, and takes an image.
The pattern position shift amount measuring unit is
From the position information of the first measurement target pattern calculated based on the image captured by the first imaging unit and the position information of the second measurement target pattern calculated based on the image captured by the second imaging unit. It is characterized by measuring the amount of deviation.

According to such a pattern position measuring device,
Since the optical path of the optical path branching portion, the first imaging unit, and the second imaging unit are branched while sharing the optical axis with respect to the imaging region, the imaging optical axis is unlikely to shift. Further, the first imaging unit focuses on the formation surface of the first measurement target pattern, the formation surface of the second measurement target pattern is out of focus for imaging, and the second image pickup unit focuses on the formation surface of the second measurement target pattern. The formation surface of the first measurement target pattern can be defocused and imaged. Then, the first measurement target pattern and the second measurement target pattern are imaged at the same time or in a short period of time, and are sequentially imaged by changing the imaging position one after another or by strobe imaging while continuously moving. Is possible.

When measuring the position of the measurement target pattern formed on the measurement target work, the measurement can be performed quickly while maintaining the measurement accuracy.

It is a schematic diagram which shows the whole structure of the example of the form which embodies the present invention. It is a schematic diagram which shows the main part of the example of the form which embodies the present invention. It is a conceptual diagram which shows the state of taking the appearance image in the example of the form which embodies the present invention. It is a flow figure in an example of the form which embodies the present invention. It is sectional drawing which shows the arrangement example of the 1st measurement target pattern of the 1st measurement target work, and the 2nd measurement target pattern of a 2nd measurement target work.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, the three axes of the Cartesian coordinate system are expressed as X, Y, and Z, the horizontal direction is expressed as the X direction and the Y direction, and the direction perpendicular to the XY plane (that is, the gravity direction) is expressed as the Z direction. do. Further, in the Z direction, the direction against gravity is expressed as the upper direction, and the direction in which gravity acts is expressed as the lower direction. Further, the direction of rotation with the Z direction as the central axis is defined as the θ direction.

FIG. 1 is a schematic view showing an overall configuration of an example of a form embodying the present invention. FIG. 1 schematically shows each part constituting the pattern position measuring device 1 according to the present invention.

The pattern position measuring device 1 measures the relative position between the first measurement target pattern S1 formed on the first measurement target work W1 and the second measurement target pattern S2 formed on the second measurement target work W2. be. In this example, a transparent glass substrate is exemplified as the first measurement target work W1 and the second measurement target work W2. On the other hand, as the first measurement target pattern S1 and the second measurement target pattern S2, a metal thin film such as aluminum or chromium is patterned on the surfaces of the works W1 and W2. In the following description, the first measurement target work W1 may be referred to as “work W1”, and the second measurement target work W2 may be referred to as “work W2”.
Specifically, the pattern position measuring device 1 includes a work holding unit 2, an imaging unit 3, and a pattern position deviation amount measuring unit 4. Further, the pattern position measuring device 1 includes a relative moving unit M, a computer CP, a controller CN, and the like.

FIG. 2 is a schematic view showing a main part of an example of a form embodying the present invention. In FIG. 2, the pattern position measuring device 1 according to the present invention is used to form the first measurement target pattern S1 formed on the surface of the first measurement target work W1 and the surface of the second measurement target work W2. The images P1 and P2 obtained by imaging the second measurement target pattern S2 by the first imaging unit 3A and the second imaging unit 3B, respectively, are shown schematically.
Here, four rectangular patterns arranged at predetermined intervals as the first measurement target pattern S1 and a cross-shaped pattern having a predetermined line width as the second measurement target pattern S2 are exemplified.

In the work holding unit 2, in the measurement of the relative position between the first measurement target pattern S1 and the second measurement target pattern S2, the first measurement target pattern S1 and the second measurement target pattern S2 having a corresponding relationship have a predetermined positional relationship. The first measurement target work W1 and the second measurement target work W2 are held so as to be maintained.
Specifically, in the work holding unit 2, the first measurement target pattern S1 and the second measurement target pattern S2, which are measurement targets at relative positions, maintain a predetermined positioning accuracy in the horizontal direction (in other words,). The first measurement target work W1 and the second measurement target work W2 are held so as to be within a predetermined position deviation allowable range). Further, in the work holding unit 2, the first measurement target pattern S1 of the first measurement target work W1 and the second measurement target pattern S2 of the second measurement target work W2 are spaced apart from each other in the thickness direction of the first measurement target work W1. The first measurement target work W1 and the second measurement target work W2 are held so that the state of being separated from each other is maintained.
More specifically, the work holding unit 2 includes a first work holding unit 21, a second work holding unit 22, and the like.

The first work holding portion 21 supports the work W1 to be measured from the lower surface side while maintaining a horizontal state, adjusts the posture in the horizontal direction, and holds the work W1 so that the posture is maintained.
Specifically, the first work holding portion 21 includes a mounting table 20, an alignment mechanism (not shown), and the like.

The mounting table 20 supports the first measurement target work W1 from the lower surface side while maintaining a horizontal state. Specifically, the mounting table 20 has a horizontal upper surface and is provided with grooves and holes in a portion in contact with the work W1 to be measured, and these grooves and holes are formed by a vacuum pump or the like via a switching valve or the like. It is connected to the negative pressure generating means of. Then, the wafer holding portion 2 can hold and release the works W1 and W2 by switching these grooves and holes to a negative pressure state or an atmospheric release state. More specifically, the upper surface of the mounting table 20 (that is, the side in contact with the first measurement target work W1) is roughened or matted.
The alignment mechanism pushes the side surface of the first measurement target work W1 and adjusts the posture in the horizontal direction.

The second work holding portion 22 supports the second work to be measured W2 from the lower surface side while maintaining a horizontal state, adjusts the posture in the horizontal direction, and holds the work W2 so that the posture is maintained.
Specifically, the second work holding portion 22 is provided with a plurality of sets of substantially L-shaped blocks, columns, actuators, etc., and while supporting the outer edge portion of the second work target work W2 from the lower surface side, pushes the side surface in the horizontal direction. It is possible to adjust the posture to maintain the gripped state or release the gripped state.
More specifically, the second work holding unit 22 is above the first measurement target work W1 (that is, on the image pickup unit 3 side) and keeps a predetermined interval from the first measurement target work W1 while maintaining the second measurement target work. It is configured to hold W2. Further, when focusing on the horizontal direction, the work W2 is aligned (outer shape positioning, etc.) and held so that the outer shapes of the first measurement target work W1 and the second measurement target work W2 overlap each other in a plan view. do.

The image pickup unit 3 captures the first measurement target pattern S1 and the second measurement target pattern S2. Specifically, the image pickup unit 3 outputs an image P1 that captures the first measurement target pattern S1 and an image P2 that captures the second measurement target pattern S2.
More specifically, the imaging unit 3 includes an optical path branching unit 3S, a first imaging unit 3A, a second imaging unit 3B, a lens barrel 30, an objective lens 32, a revolver 33, an illumination unit 34, a half mirror 35, and the like. There is.

The optical path branching portion 3S branches the imaging optical path 3L into the first optical path LA and the second optical path LB while sharing the optical axis with respect to the imaging regions F1 and F2.
Specifically, the optical path branching portion 3S passes through the objective lens 32 and guides the imaging optical path 3L into the lens barrel 30 in two directions (in the figure, the upper part is the first optical path LA and the right side is the second optical path). It branches to LB).
More specifically, the optical path branching portion 3S is composed of an optical element called a beam splitter, and a part (for example, 50%) of the light incident from below the optical path branching portion 3S is made to travel straight and the first is upward. It is emitted as an optical path LA, and the rest (for example, 50%) is reflected and emitted as a second optical path LB to the right.

The first image pickup unit 3A takes an image of the image pickup region F1 via the first optical path LA and outputs image data.
Specifically, the first image pickup unit 3A focuses on the surface S1 on which the first measurement target pattern P1 of the first measurement target work W1 is formed and takes an image.
More specifically, the first imaging unit 3A includes an imaging camera 36A, an imaging lens 38A, and the like.

The image pickup camera 36A includes an image pickup element 37A, and outputs the captured image as a video signal or image data to the outside. Specifically, the image pickup camera 36A can be exemplified by having a CCD, a CMOS type image sensor chip, or the like as an image pickup element 37A.
The image pickup lens 38A forms an image of the first measurement target pattern S1 formed on the surface of the first measurement target work W1 to be imaged through the objective lens 32 on the image pickup element 37A.

The second image pickup unit 3B takes an image of the image pickup region F2 via the second optical path LB and outputs image data.
Specifically, the second image pickup unit 3B focuses on the surface S2 on which the second measurement target pattern P2 of the second measurement target work W2 is formed and takes an image.
More specifically, the second image pickup unit 3B includes an image pickup camera 36B, an image pickup lens 38B, and the like.

The image pickup camera 36B includes an image pickup element 37B and outputs the captured image as a video signal or image data to the outside. Specifically, the image pickup camera 36B can be exemplified by having a CCD, a CMOS type image sensor chip, or the like as an image pickup element 37B.
The image pickup lens 38B forms an image of the second measurement target pattern S2 formed on the surface of the second measurement target work W2 to be imaged through the objective lens 32 on the image pickup element 37B.

The image pickup by the first image pickup unit 3A and the image pickup by the second image pickup unit 3B are performed simultaneously or within a short period of time. Specifically, when a light emitting signal is output from the control unit CP to the illumination unit 34 and the illumination light L1 is irradiated, both the first image pickup unit 3A and the second image pickup unit 3B perform imaging. , The image pickup trigger output to the first image pickup unit 3A and the image pickup trigger output to the second image pickup unit 3B are simultaneously performed. The term "simultaneous" as used herein means not only a completely zero time lag, but also a time lag that can be regarded as simultaneous processing in consideration of the delay time of cycle processing of the control device, etc., resulting in a signal. Including the case of output. Further, both the first image pickup unit 3A and the second image pickup unit 3B are made capable of taking an image before the light emission signal is output to the illumination unit 34, and the illumination unit 34 is subjected to each exposure time before the exposure time elapses. The case of outputting a light emission signal (that is, emitting a common illumination light L1) is also included in "simultaneous imaging". Further, "for a short period of time" means a time lag that can be tolerated to the extent that the inspection time is not significantly delayed.

More specifically, the image pickup cameras 36A and 36B capture the image pickup areas F1 and F2 set in the works W1 and W2 and acquire the images P1 and P2. The acquired images P1 and P2 are output to the outside (computer CP in this embodiment) as video signals and video data.

FIG. 3 is a conceptual diagram showing a state of capturing an external image in an example of a form embodying the present invention.
In FIG. 3, the image pickup cameras 36A and 36B of the image pickup unit 3 take images of the image pickup areas F1 and F2 set on the works W1 and W2 while moving relative to the work W1 and W2 in the direction indicated by the arrow Vs. It is shown how to do it.

The lens barrel 30 fixes the optical path branching portion 3S, the first imaging unit 3A, and the second imaging unit 3B in a predetermined positional relationship.
Specifically, the lens barrel 30 has a substantially T-shape inside so as to guide the observation light L2 incident from the objective lens 32 to the first image pickup unit 3A and the second image pickup unit 3B while blocking the outside light. It has a hollow (also called hollow) tubular shape. The revolver 33 is attached to one end side (lower side in the figure) of the lens barrel 30, and the first image pickup unit 3A and the second image pickup unit 3B are attached to the other end side (upper side and right side in the figure). An optical path branch portion 3S is attached to the inside of the lens barrel 30. Further, the lens barrel 30 shown in this example has a double branching structure, and a lighting unit 34 and a half mirror 35 are attached between the revolver 33 and the optical path branching portion 3S.
Further, the lens barrel 30 is attached to the device frame 1f via a connecting metal fitting or the like (not shown).

The objective lens 32 forms an image of the image pickup regions F1 and F2 on the works W1 and W2 on the image pickup elements 37A and 37B of the image pickup cameras 36A and 36B at different predetermined observation magnifications. Specifically, the objective lens 32 includes objective lenses 32a and 32b having different magnifications.
The objective lens 32 is separated from the surface of the first measurement target work W1 (that is, the surface on which the first measurement target pattern S1 is formed) and the working distance WD1 and the surface of the second measurement target work W2 (that is, the first surface). 2 The surface on which the measurement target pattern S2 is formed) and the working distance WD2 are separated from each other.

The revolver 33 switches the magnification of the objective lens 32 to be used. Specifically, a plurality of objective lenses 32a and 32b having different magnifications are attached to the revolver 33, and the lens magnification is increased by rotating and stationary by a predetermined angle based on manual or external signal control. Can be switched.

The illumination unit 34 emits the illumination light L1 necessary for imaging.
Specifically, the illumination unit 34 irradiates the first measurement target work W1 and the second measurement target work W2 with illumination light L1 containing a plurality of wavelength components.
More specifically, the lighting unit 34 can be exemplified by a laser diode, a metal halide lamp, a xenon lamp, LED lighting, etc., and can switch between light emission / extinguishing based on external signal control, and strobe at a predetermined place and timing. It makes it emit light.

The half mirror 35 reflects the illumination light L1 emitted from the illumination unit 34, irradiates the work W1 and W2 to be measured, and passes the observation light L2 incident from the work W1 and W2 to the image pickup unit 3. It is something that makes you.
Since the first measurement target pattern S1 and the second measurement target pattern S2 are separated from each other in the thickness direction (Z direction) of the works W1 and W2, the image P1 focuses on the second measurement target pattern S2. The pattern S2 is blurred because it does not match, and the pattern S1 is blurred in the image P2 because the first measurement target pattern S1 is out of focus.

The pattern position deviation amount measuring unit 4 measures the deviation amounts dX and dY between the first measurement target pattern S1 and the second measurement target pattern S2.
Specifically, the pattern misalignment amount measuring unit 4 has the position information of the first measurement target pattern S1 calculated based on the image P1 captured by the first imaging unit 3A and the image captured by the second imaging unit 3B. From the position information of the first measurement target pattern S2 calculated based on P2, the deviation amounts dX and dY of these patterns S1 and S2 are calculated (that is, measured).
More specifically, the pattern position deviation amount measuring unit 4 is configured as a part of the computer CP, and is programmed to perform the following processing.

First, the acquired image P1 is image-processed, and the position of the center (or the center of gravity) C1 of the first measurement target pattern S1 composed of four quadrangles is calculated. Further, the acquired image P2 is image-processed to calculate the position of the center (or the center of gravity) C2 of the cross-shaped second measurement target pattern S2. Then, the deviation amount dX in the X direction and the deviation amount dY in the Y direction of the centers C1 and C2 are calculated. The positions of these centers C1 and C2 can be represented by relative positions from reference positions (for example, upper left or center) in the images P1 and P2. In the pattern position deviation amount measuring unit 4, the deviation amount dX, dY in which the number of pixels is converted into a unit based on the pixel pitch of the images P1 and P2 and the magnification of the objective lens 32 registered in advance. Is calculated.
The relative positional deviation between the reference positions in the images P1 and P2 (so-called assembly error) is measured and corrected (so-called calibration) in advance.

The relative moving unit M moves the work holding unit 2 and the imaging unit 3 relative to each other.
Specifically, the relative moving portion M includes an X-axis slider M1, a Y-axis slider M2, and a rotation mechanism M3.

The X-axis slider M1 is mounted on the device frame 1f, and the Y-axis slider M2 is moved in the X direction at an arbitrary speed and stopped at an arbitrary position. Specifically, the X-axis slider is composed of a pair of rails extending in the X direction, a slider unit that moves on the rails, and a slider drive unit that moves and stops the slider unit.

The Y-axis slider M2 moves the rotation mechanism M3 in the Y direction at an arbitrary speed based on a control signal output from the control unit CN, and makes the rotation mechanism M3 stationary at an arbitrary position. Specifically, the Y-axis slider is composed of a pair of rails extending in the Y direction, a slider unit that moves on the rails, and a slider drive unit that moves and stops the slider unit.

The slider drive unit of the X-axis slider M1 and the Y-axis slider M2 may be composed of a servo motor that rotates and stands still by signal control from the control unit CN, a combination of a pulse motor and a ball screw mechanism, a linear motor mechanism, and the like. can.

The rotation mechanism M3 rotates the mounting table 20 in the θ direction at an arbitrary speed and makes it stand still at an arbitrary angle. Specifically, the rotation mechanism M3 can be exemplified as a rotation / stationary mechanism such as a direct drive motor that is rotated / stationary at an arbitrary angle by signal control from an external device. The mounting table 20 of the work holding portion 2 is mounted on the member on the rotating side of the rotating mechanism M3.

Since the relative moving portion M has such a configuration, the workpieces W1 and W2 are made independent of the imaging unit S in the XYθ direction while holding the workpieces W1 and W2 to be inspected, or are combined. In addition, it can be moved relative to each other at a predetermined speed and angle, or can be stationary at an arbitrary position and angle.

The computer CP inputs signals and data from the outside, performs predetermined arithmetic processing and image processing, and outputs the signals and data to the outside. For example, the computer CP executes the following functions.
-Registration of pixel pitch and imaging magnification of imaging camera-Registration of inspection recipe (imaging position, imaging order, imaging interval (pitch, interval), movement speed, etc.), switching of inspection recipe to be used, etc.-Acquired images P1, P2 Image processing / detected patterns S1 and S2 for position measurement and unit conversion More specifically, the computer CP has an input unit and an output unit, a storage unit (called a register or a memory), and a control unit and an arithmetic unit (CPU or unit). It is composed of an image processing device (called GPU), an auxiliary storage device (HDD, SSD, etc.) (that is, hardware), and an execution program thereof (that is, software) (called MPU).

The controller CN inputs and outputs signals and data to and from external devices (work holding unit 2, imaging unit 3, relative moving unit M and other devices, computer CP), and performs predetermined control processing. For example, the following. It performs the function of.
-Outputs the holding / releasing signals of the works W1 and W2 to the work holding unit 2.-Controls the revolver 33 to switch the objective lens 32 (imaging magnification) to be used.-Strobe light emission to the lighting unit 34. Outputs the signal of ・ Outputs the image pickup trigger to the image pickup cameras 36A and 36B ・ Inputs the images P1 and P2 output from the image pickup cameras 36A and 36B ・ Drive control of the relative moving unit M: X-axis sliders M1 and Y-axis A function to output and control a drive signal while monitoring the current positions of the slider M2 and the rotation mechanism M3. That is, the controller CN drives and controls the relative moving unit M and captures images set on the workpieces W1 and W2. The image pickup trigger can be output to the image pickup unit 3 while changing the locations of the areas F1 and F2. Further, the image pickup magnification and the field of view size can be switched according to the inspection type, and the image pickup trigger can be output while changing the image pickup interval, and a desired image can be acquired.

The output of the image pickup trigger can be exemplified by the following method.
-A method in which the illumination light L1 is emitted for a very short time (so-called strobe emission) every time the illumination light L1 is moved while scanning and moving in the X direction.
-A method of moving to a predetermined position and making it stationary and irradiating the illumination light L1 to take an image (so-called step & repeat).

More specifically, the controller CN is composed of a part of a computer CP, a dedicated programmable logic controller (that is, hardware), and an execution program thereof (that is, software).

<Operation flow>
FIG. 4 is a flow chart in an example of a form embodying the present invention. FIG. 5 shows a configuration in which measurement target patterns S1 and S2 arranged on the workpieces W1 and W2 are imaged using the above-mentioned pattern position measuring device 1 and the deviation amount of these measurement target patterns S1 and S2 is measured. It is shown step by step as a series of flows.

First, the measurement recipe is registered and selected, and the position information and the imaging order of the measurement target patterns S1 and S2 are set (step s10).

Subsequently, the first work to be measured W1 is placed on the mounting table 20 and aligned and held by the first work holding unit 21 (step s11).

Further, the second work to be measured W2 is aligned and held by the second work holding unit 22 (step s12).

Then, while the work holding unit 2 and the imaging unit 3 are relatively moved, imaging is performed (that is, images P1 and P2 are acquired) (step s13).

Image processing or the like is performed on the acquired images P1 and P2, and the positions of the measurement target pattern S1 in the image P1 and the measurement target pattern S2 in the image P2 are calculated (step s14).

Then, the deviation amount of the measurement target patterns S1 and S2 is calculated (that is, measured) from the positions of the measurement target patterns S1 and S2 in the images P1 and P2 (step s15).

Then, it is determined whether or not to continue the measurement (step 16), and if it is to be continued, the above-mentioned steps s13 to s16 are repeated. On the other hand, when the measurement is not continued, the second measurement target work W2 is taken out (step s17).

Then, it is determined whether or not to measure the deviation amount with respect to the next measurement target work W2 (step s18), and when the measurement is performed, the above-mentioned steps s10 to s18 are repeated. On the other hand, when the measurement is not performed, the first measurement target work W1 is taken out (step s19).

Then, it is determined whether or not to perform another measurement, and when the measurement is performed, the above steps s10 to s20 are repeated. On the other hand, when no measurement is performed, a series of flows is terminated.

Since it has such a configuration, the pattern position measuring device 1 has a pattern position measuring device 1.
Since the optical path branch portion 3S, the first image pickup unit 3A, and the second image pickup unit 3B are fixed in a predetermined positional relationship by one lens barrel 30, the image pickup optical axis is unlikely to shift in position. Further, the first image pickup unit 3A focuses on the formation surface of the first measurement target pattern S1, the formation surface of the second measurement target pattern S2 is out of focus, and the second image pickup unit 3B focuses on the second measurement target. The formed surface of the pattern S2 can be focused, and the formed surface of the first measurement target pattern S1 can be defocused for imaging. Then, the first measurement target pattern S1 and the second measurement target pattern S2 are simultaneously imaged, and the strobe imaging is possible while changing the imaging position one after another or during continuous movement. ..

Therefore, when measuring the positions of the measurement target patterns S1 and S2 formed on the measurement target workpieces W1 and W2, the measurement can be performed quickly while maintaining the measurement accuracy.

For example, by applying the present invention, it is possible to grasp the deviation amounts dX and dY of the patterns of the workpieces W1 and W2 to be bonded, and to predict and inspect the result before bonding.
Further, if the position information of either one of the measurement target patterns S1 and S2 is known, it is treated as a reference pattern (that is, a ruler), and the deviation amount and the position information of the other pattern are accurately measured. Can be done.

(Another form)
In the above description, as a configuration example embodying the present invention, a pattern position measuring device 1 for measuring the displacement amounts dX and dY of the measurement target patterns S1 and S2 formed on the measurement target workpieces W1 and W2 has been exemplified.
However, the present invention is not limited to the above-mentioned configuration, and can be embodied by the pattern position measuring device 1B having the following configuration (see FIG. 1).

The pattern position measuring device 1B handles the above-mentioned first measurement target work W1 as a reference work for position measurement, and measures the position of the second measurement target pattern S2 formed on the second measurement target work W2. ..

Specifically, the pattern position measuring device 1B registers the position information of the first measurement target pattern S1 in advance, replaces the second measurement target work W2 while holding the first measurement target work W1, and first. It is configured to measure the deviation amounts dX and dY of the measurement target pattern S1 and the second measurement target pattern S2, and calculate (that is, measure) the position of the second measurement target pattern S2.

More specifically, the pattern position measuring device 1B includes a reference position registration unit 5 and a pattern position calculation unit 6 in addition to the pattern position measuring device 1 described above.

The reference position registration unit 5 registers the position information of the first measurement target pattern S1 formed by the first measurement target work W1 as the measurement reference of the position of the second measurement target pattern S2.
Specifically, the position information (so-called accurate position) of the first measurement target pattern S1 measured by another length measuring device or the like is registered in the reference position registration unit 5.
More specifically, the reference position registration unit 5 defines the coordinate system of the work W1 based on the outer shape and the alignment mark of the first measurement target work W1, and the first measurement target pattern S1 in the coordinate system is defined. The coordinates of the center position and the position of the center of gravity of the pattern S1 are registered as the position information of the pattern S1.

The pattern position calculation unit 6 has the deviation amounts dX and dY between the first measurement target pattern S1 and the second measurement target pattern S2 measured by the pattern position deviation amount measurement unit 4, and the first registered in the reference position registration unit 5. The position of the second measurement target pattern S2 is calculated based on the position information of the measurement target pattern S1.
Specifically, the pattern position calculation unit 6 uses the position information (coordinates, etc.) of the first measurement target pattern S1 registered in the reference position registration unit 5 as the deviation amount dX, measured by the pattern position deviation amount measurement unit 4. By adding or subtracting dY, the position (coordinates, etc.) of the second measurement target pattern S2 is calculated.

Since the pattern position measuring device 1B has such a configuration, the pattern position measuring device 1B uses the first measurement target work W1 as a reference work (so-called ruler) and holds the first measurement target work W1 while holding the second measurement target work W1. W2 can be replaced to measure the position of the second measurement target pattern formed on the work W2.

(Modification example of optical path branch portion 3S)
The illumination light L1 emitted from the illumination unit 34 of the image pickup unit 3 may be monochromatic light or light containing a plurality of wavelength components. The term "plurality of wavelength components" as used herein refers to cases where multiple components of monochromatic light (also referred to as monochromatic light) such as red, green, and blue are included, or light in a wide wavelength band including these (light blue, yellow). , White, etc.). The optical path branching portion 3S and the half mirror 35 coat the surface and the interface so that the reflected / branched light contains a plurality of wavelength components as in the illumination light L1. Set the rate etc.

However, the optical path branching portion 3S is not limited to the above-mentioned configuration, and the light branched by the optical path branching portion 3S has different wavelength components on the first imaging unit 3A side and the second imaging unit 3B side. There may be. The specific configuration is as follows.

A lighting unit 34 for irradiating the first measurement target work W1 and the second measurement target work W2 with illumination light L1 containing a plurality of wavelength components is provided.
The image pickup unit 3 is irradiated from the illumination unit 34, passes through the second measurement target pattern S2 or the second measurement target work W2, and passes through the second measurement target work W2, and passes through the first measurement target pattern S1 or the first measurement target work. The light reflected on the surface of W1 is imaged and
In the optical path branching unit 3S, the main wavelength of the light (light of the first optical path LA) imaged by the first image pickup unit 3A is the main wavelength of the light (light of the second optical path LB) imaged by the second image pickup unit 3B. Is set to be different from.

More specifically, the illumination light L1 contains blue (wavelength: about 470 nm) and red (wavelength: about 630 nm) wavelength components, and the first image pickup unit 3A captures red light, and the second image pickup unit 3B It may be set to capture blue light at. In this case, the optical path branching portion 3S determines the thickness, transmittance, reflectance, etc. of the film forming the surface or interface so as to allow light having a component having a wavelength of 550 nm or less to pass through and reflect light having a component having a wavelength of 550 nm or more. Set. Alternatively, the first optical path LA is provided with a filter 39A that allows light having a wavelength of 550 nm or less to pass through and absorbs or reflects light having a wavelength of 550 nm or more, and the second optical path LB contains light having a wavelength of 550 nm or more. The configuration is provided with a filter 39B that allows light to pass through and absorbs or reflects light having a wavelength of 550 nm or less.

That is, it is preferable that the image pickup unit 3 captures the first measurement pattern S1 in the focused state and does not reflect the second measurement pattern S2 in the image P1 captured by the first image pickup unit 3A. On the other hand, in the image P2 captured by the second imaging unit 3B, it is preferable that the second measurement pattern S2 is captured in the focused state and the first measurement pattern S1 is not reflected.

(Modification example of lighting unit 34)
In the above description, the illumination unit 34 of the image pickup unit 3 is set to coincide with the image pickup optical axis of the image pickup unit 3 so that the optical axis with respect to the image pickup region is set to coincide with the image pickup optical axis.
With such a configuration, when the reflectance of the first measurement target pattern S1 or the second measurement target pattern S2 is high, it is easy to acquire an image with high contrast, and the relative movement of the image pickup unit 3 with respect to the works W1 and W2 It is preferable because it is easy to do.

However, in applying the present invention, the irradiation method of the illumination light L1 is not limited to the above configuration, and oblique light illumination that irradiates the surface of the second measurement target work W2 with the illumination light L1 at a predetermined angle is used. As the observation light L2, a method of observing scattered light may be used. Alternatively, the illumination unit 34 is arranged below the first measurement target work W1 (that is, on the mounting table 20 side), and the illumination light L1 is irradiated upward (that is, the image pickup unit 3) (so-called transmission method). Lighting) may be used.

(Transformation example of target work and pattern)
In the above description, a transparent glass substrate is exemplified as the first measurement target work W1 and the second measurement target work W2, and the first measurement target pattern S1 and the second measurement target pattern S2 are metal thin films such as aluminum and chromium. The patterned one is illustrated. However, in applying the present invention, the measurement target works W1 and W2 and these measurement target patterns S1 and S2 may be made of other materials, and the wavelength of the light emitted from the illumination unit 34 may be set. It can be set as appropriate.

For example, the second measurement target work W2 may be a silicon wafer, and the light emitted from the illumination unit 34 may be set to wavelengths in the visible light region and the infrared light region.
In this case, the image pickup unit 3 has a configuration in which the first measurement target pattern S1 is imaged by infrared light and the second measurement target pattern S2 is imaged by visible light.
The image pickup cameras 36A and 36B of the image pickup unit 3 are configured to include image pickup elements 37A and 37B having optimum sensitivities to the wavelengths of the received light, respectively.
Specifically, the image pickup camera 36A of the first image pickup unit 3A that captures the first measurement target pattern S1 with infrared light is equipped with an image pickup element having high light receiving sensitivity of infrared light, and is the first with visible light. 2. It is preferable to use an image pickup camera 36B of the second image pickup unit 3B for taking an image of the measurement target pattern S2, which is provided with an image pickup element having high light receiving sensitivity of visible light. Further, in consideration of the influence of the transmittance of the second measurement target work W2, the image pickup cameras 36A and 36B appropriately set parameters such as exposure and shutter speed according to the amount of light received (also referred to as intensity). Just do it.
By doing so, only the first measurement target pattern S1 formed on the surface of the first measurement target work W1 by using the infrared light transmitted through the second measurement target work W2, which is a silicon wafer, is the first image pickup unit. The image P1 captured by 3A is imaged in a focused state and with a desired brightness and contrast. On the other hand, in the image P2 captured by the second image pickup unit 3B, only the second measurement target pattern S2 formed on the second measurement target work W2 is captured in a focused state with a desired brightness and contrast.

(Example of placement of target work and pattern)
FIG. 5 is a cross-sectional view showing an arrangement example of the first measurement target pattern S1 of the first measurement target work W1 and the second measurement target pattern S2 of the second measurement target work W2 in the embodiment of the present invention. For example, as shown in FIGS. 5A to 5C, the first measurement target pattern S1 is upward or downward, and the first measurement target pattern S1 is separated from the upper surface of the first measurement target work W1 and the lower surface of the second measurement target work W2. 2 The works W1 and W2 are held so that the measurement target pattern S2 faces upward or downward. Then, the first measurement target pattern S1 and the second measurement target pattern S2 are separated by a predetermined interval D. Alternatively, as shown in FIGS. 5 (d) to 5 (f), the first measurement target pattern S1 and the second measurement target pattern are in contact with the upper surface of the first measurement target work W1 and the lower surface of the second measurement target work W2. These works W1 and W2 are held so that both of S2 face upward or downward, or the first measurement target pattern S1 faces downward and the second measurement target pattern S2 faces upward. Then, the first measurement target pattern S1 and the second measurement target pattern S2 are separated by a predetermined interval D.
Further, paying attention to the horizontal direction, the outer shape is positioned (aligned) and held so that the outer shapes of the first measurement target work W1 and the second measurement target work W2 overlap each other in a plan view.

In the above description, as the first work holding portion 21, the configuration in which the lower surface of the first work W1 to be measured is brought into contact with the upper surface of the mounting table 20 and held is shown. However, in applying the present invention, the first work holding portion 21 is not limited to such a configuration, and supports the outer edge portion of the first work to be measured W1 from the lower surface side like the second work holding portion 22. At the same time, the posture may be adjusted in the horizontal direction by pushing the side surface toward the center, and the grip may be formed.

In the above description, the image pickup cameras 36A and 36B have an image of the first measurement target pattern S1 formed on the surface of the first measurement target work W1 and a second measurement target pattern S2 formed on the surface of the second measurement target work W2. The configuration for imaging the image of the above is illustrated.

However, the first measurement target pattern S1 is not limited to the configuration formed on the surface of the first measurement target work W1, and may be formed on the inner surface of the first measurement target work W1. In this case, the working distance WD1 between the objective lens 32 and the first measurement target pattern S1, the curvature of the image pickup lens 38A, the distance fa between the image pickup element 37A and the image pickup lens 38A, and the like may be appropriately adjusted.
Similarly, the second measurement target pattern S2 is not limited to the configuration formed on the surface of the second measurement target work W2, and may be formed on the inner surface of the second measurement target work W2. In this case, the working distance WD2 between the objective lens 32 and the second measurement target pattern S2, the curvature of the imaging lens 38B, the distance fb between the imaging element 37B and the imaging lens 38B, and the like may be appropriately adjusted.

(Shape, number of patterns S1 and S2 to be compared)
In the above description, four rectangular patterns arranged at predetermined intervals as the first measurement target pattern S1 and a cross-shaped pattern having a predetermined line width as the second measurement target pattern S2 are exemplified. However, these patterns S1 and S2 are not limited to such a shape, number, and layout, and may be variously modified.

Further, in the above description, an example in which the first and second measurement target patterns S1 and S2 are arranged one by one in the images P1 and P2 has been described in detail. However, a plurality of sets of the first and second measurement target patterns S1 and S2 may be included in the images P1 and P2.
Further, the first and second measurement target patterns S1 and S2 may have the same number and one-to-one correspondence, but a plurality of second measurement target patterns SS2 (so-called) for one first measurement target pattern S1. It may be 1 to n). Alternatively, one second measurement target pattern S2 (so-called n to 1) may be used for a plurality of first measurement target patterns S1.

(Modification example of image pickup unit 3)
In the above description, as the image pickup unit 3, the configuration in which the image pickup lens 38A is provided in the first image pickup unit 3A and the image pickup lens 38B is provided in the second image pickup unit 3B is exemplified. However, these imaging lenses 38A and 38B are not essential configurations for embodying the present invention. For example, while omitting these imaging lenses 38A and 38B, the first measurement target pattern S1 is imaged on the image pickup element 37A of the image pickup camera 36A, and the second measurement target pattern S2 is imaged on the image pickup element 37B of the image pickup camera 36B. It may be configured to include a common image pickup lens 38C (FIG. 2, shown by a broken line) as described above. In this case, the distances between the imaging lens 38C and the imaging cameras 36A and 36B are appropriately set according to the working distances WD1 and WD2 between the objective lens 32 and the measurement target patterns S1 and S2. Further, in this configuration, since the imaging magnification differs between the first imaging unit 3A and the second imaging unit 3B, the configuration is such that conversion (so-called scaling correction) is performed when calculating the position information and the like.

In the above description, the configuration in which the image pickup unit 3 is provided with a plurality of objective lenses 32a and 32b and the revolver 33 is exemplified. However, in embodying the present invention, the imaging unit 3 is not limited to such a configuration, and may be provided with three or more objective lenses, or may be provided with only one.

(Modification example of work holding portion 2)
In the above description, as the work holding portion 2, the first measurement target pattern S1 of the first measurement target work W1 and the second measurement target pattern S2 of the second measurement target work W2 are separated in the thickness direction of the first measurement target work. The configuration for holding the first measurement target work W1 and the second measurement target work W2 (that is, the upper surface of the first measurement target work W1 and the lower surface of the second measurement target work W2 are separated from each other so that the first measurement target work W1 and the second measurement target work W2 are held in the same state. ) Is illustrated. However, in embodying the present invention, these works W1 and W2 are not limited to such an arrangement and may be appropriately modified.

1 Pattern position measuring device 2 Work holding unit 3 Imaging unit 4 Pattern misalignment measurement unit 5 Reference position registration unit 6 Position measuring unit 20 Mounting table 21 1st work holding unit 22 2nd work holding unit 3A 1st imaging unit 3B 2 Imaging unit 3S Optical path branch 3L Imaging optical path 30 Lens barrel 32 Objective lens (32a, 32b)
33 Revolver 34 Illumination unit 35 Half mirror 36A, 36B Image sensor 37A, 37B Image sensor 38A, 38B, 38C Imaging lens 39A, 39B Bandpass filter W1 First measurement target work W2 Second measurement target work S1 First measurement target pattern (C1: Its center / center of gravity)
S2 Second measurement target pattern (C2: its center / center of gravity)
P1 image (first measurement target pattern)
P2 image (second measurement target pattern)
fa, fb Focal length WD1, WD2 Working distance M Relative moving part CP computer CN controller

Claims (4)

A pattern position measuring device that measures the relative position between the first measurement target pattern formed on the first measurement target work and the second measurement target pattern formed on the second measurement target work.
The first measurement target work and the second measurement target work are held so that the first measurement target pattern and the second measurement target pattern having a corresponding relationship in the relative position measurement maintain a predetermined positional relationship. Work holding part and
An imaging unit that captures the first measurement target pattern and the second measurement target pattern, and
A pattern position deviation amount measuring unit for measuring the deviation amount between the first measurement target pattern and the second measurement target pattern is provided.
The image pickup unit is
An optical path branching portion that branches the imaging optical path into the first optical path and the second optical path while sharing the optical axis with respect to the imaging region.
A first image pickup unit that captures an image pickup region via the first optical path, and a first image pickup unit.
A second imaging unit for imaging the imaging region via the second optical path is provided.
The first image pickup unit focuses on the surface of the first measurement target work on which the first measurement target pattern is formed, and takes an image.
The second image pickup unit focuses on the surface of the second measurement target work on which the second measurement target pattern is formed, and takes an image.
The pattern misalignment amount measuring unit is
The position information of the first measurement target pattern calculated based on the image captured by the first imaging unit and the second measurement target pattern calculated based on the image captured by the second imaging unit. A pattern position measuring device, characterized in that the deviation amount is measured from the position information. As a reference for measuring the position of the second measurement target pattern, a reference position registration unit for registering the position information of the first measurement target pattern formed on the first measurement target work, and a reference position registration unit.
Based on the deviation amount between the first measurement target pattern and the second measurement target pattern measured by the pattern position deviation amount measuring unit and the position information of the first measurement target pattern registered in the reference position registration unit. The pattern position measuring device according to claim 1, further comprising a pattern position calculating unit for calculating the position of the second measurement target pattern. A lighting unit that irradiates the first measurement target work and the second measurement target work with illumination light containing a plurality of wavelength components is provided.
The image pickup unit is irradiated from the illumination unit, passes through the second measurement target pattern or the second measurement target work, and the second measurement target work, and passes through the first measurement target pattern or the first measurement target. The light reflected on the surface of the work is imaged and
The optical path branching portion is characterized in that the main wavelength of the light imaged by the first imaging unit is set to be different from the main wavelength of the light imaged by the second imaging unit. The pattern position measuring apparatus according to claim 1 or 2. The pattern position measuring device according to claim 3, wherein the illumination unit is of a coaxial tilting method in which the optical axis with respect to the image pickup area is set to coincide with the image pickup optical axis of the image pickup unit. ..

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