JPH01209305A - Device for detecting position - Google Patents

Abstract

PURPOSE:To realize high accuracy by a method wherein a horizontal dislocation detector system and an interval measuring system are composed as one head and a part of a projecting system and a receiving system is shared so that interval control at a position for detecting horizontal dislocation can be evaluated by the same system. CONSTITUTION:A light beam from a light source 31 is projected through a collimator lens 32, a projecting lens 33 and a projecting mirror 34 to an evaluation mark 20. The light beam emitted from this projection mark 20 is led to a detector system by a detecting lens 36, split by a half mirror 37, and detected by a photodetector 38 for horizontal dislocation detection and a photodetector 39 for detecting interval. A mark for detecting horizontal dislocation and a mark for measuring interval are provided adjacent to each other on the evaluation mark 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting positional and interval deviations between a mask and a mask in semiconductor manufacturing equipment.

[Prior art]

As the density of circuits increases, the minimum line width becomes smaller (minimum line width), and the requirements for alignment accuracy between the mask and the wafer 1 in semiconductor manufacturing equipment become higher (from submicron or less to several tens of nanometers).

To this end, it is increasingly important to simultaneously control the influence of the gap between the mask and the wafer.

Conventionally, regarding alignment (lateral shift control), alignment marks have been provided on a mask and a wafer, and alignment has been performed based on their positional information. On the other hand, regarding interval control, a separate interval measurement system has been provided for control.

Some alignment methods perform evaluation by detecting pattern deviations on the mask and wafer 1 through image processing, or by detecting the focal point position of the irradiation beam using a zone plate as a mark. Among them, the method of fabricating one zone plate each for the mask and wafer and detecting the positional deviation of the incident beam is attracting attention because it is not easily affected by mark defects (US Pat. No. 4,037,969,
Japanese Patent Publication No. 56-157033). FIG. 9 shows its configuration.

The parallel beam emitted from the light source 72 is focused by a condensing lens 76, passes through a condensing point 78, and is irradiated onto the alignment mark on the mask 68 and the alignment mark on the wafer 60. These alignment marks are composed of reflective zone plates, each of which has a focal point on a plane perpendicular to the optical axis including 78.The displacement of the focal point on this plane is detected using lenses 76 and 80. It is guided onto the detector 80 and detected.

At this time, FIG. 10 is a detailed explanation of the image formation relationship of light from the mark for mark and the mark for wafer.

A portion of the light beam diverged from the condensing point 78 is diffracted by the mask mark on the mask 68 to form a condensing point that focuses the mask position in the vicinity of the condensing point 78 . Also, some mask 6
8 as 0th-order transmitted light and transfers it to the wafer 6 without changing the wavefront.
The light diffracted by the wafer mark irradiated onto the alignment mark 0 passes through the mask 68 again as zero-order transmitted light, and is focused near 78 to form a focusing point that determines the wafer position.

In other words, when forming a light condensing point using the wafer 60, the mask only functions as a transparent light.

The position of the focal point due to the wafer mark formed in this way is approximately the same as Δσ′ along the plane perpendicular to the optical axis including 78 according to the deviation Δσ of the wafer with respect to the mask.
You will only have to move.

On the other hand, as a method for measuring intervals, Japanese Patent Laid-Open No. 61-111
A beam oblique incidence method such as that described in Japanese Patent No. 402, etc. is commonly used for its high sensitivity. FIG. 11 shows its configuration. Measurement is performed by projecting a light beam obliquely and receiving reflected light from the mask surface and wafer surface with a sensor on the opposite side. The light rays are converged to a condensing point Ps by the lens L1 (The light rays are reflected when they hit the mask M and the wafer W and are projected onto the screen S,
2, the light is focused on the points PM and PW. The distance between the mask and the wafer is measured from the distance between PM and PW.

[Problem that the invention is trying to solve] However,
In order to make full use of the performance of each alignment method in the conventional example, it is necessary to evaluate the interval control as shown in the conventional example in the same region of the mask and wafer in a synchronous manner using the same system.

If this point is not met, vibration or other fluctuations may occur between the mask wafers during the transition from interval measurement to alignment measurement, or differences in measurement conditions may occur due to differences between alignment mark positions and interval measurement positions, or wafer warpage may occur. There remain problems such as the inability to correct errors in alignment signals caused by distance measurement by measuring the distance, making it impossible to perform precise positioning. Previously, the alignment system (lateral deviation detection system) and spacing measurement system were installed separately at separate locations, and each measurement position was also separated accordingly, resulting in different measurement conditions and a lack of precision. .

Furthermore, having separate alignment systems and distance measurement systems makes the device thick and complicated, making it difficult to correct setting errors.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art described above, it is an object of the present invention to provide a position detection device that simultaneously realizes highly accurate lateral shift detection and distance measurement, and can be made compact.

[Means to solve the problem]

According to one embodiment of the present invention, the above-mentioned problems are solved.
In one embodiment, the alignment system and distance measuring system are configured as the same head, and the light projecting system and light receiving system are shared, thereby attempting to solve the above problems.

That is, a head incorporating a lateral shift detection system and a spacing measurement system (hereinafter referred to as a pickup head) projects light onto alignment marks and spacing measurement marks on the mask and wafer surface, and the pickup head receives light from each mark. The entire pickup head is set on a moving means such as a high-precision stage to constitute a measurement system and promptly respond to changes in mark position due to changes in mark size and process.

FIGS. 1(a) and 1(b) show an embodiment of the present invention, in which (a) shows the entire semiconductor printing apparatus viewed from the side, and FIG. 1(b) shows only the alignment pickup device section taken out. In this embodiment, a dual power grating lens method is used as a lateral shift detection system, and a mask lens A2F method is used as an interval measurement system. A brief description of these methods is as follows.

The dual power grating method is a type of alignment method that uses a grating lens element, such as a Fresnel zone plate, and passes a light beam between the grating lens on the mask and the grating lens on the wafer. In this method, the grating lens system magnifies the amount of positional deviation by a predetermined magnification, deflects the light beam, and detects the amount of positional deviation from the center of gravity of the light beam on the sensor. In this method, the amount of positional deviation is detected by magnifying it by the magnification of the grating lens system, so positional deviation detection can be performed with higher precision and resolution.

FIG. 6 shows the arrangement of a system that magnifies and detects the amount of positional deviation using a grating lens system.

The mask 1 is attached to a membrane 97, which is supported by the aligner body 95 via a mask chuck 96. A mask-wafer alignment head 94 is arranged above the main body 95. Alignment marks 41M and 41 are used to align the mask l and wafer 2.
W is burned onto the mask l and the wafer 2, respectively.

The light beam emitted from the light source 31 is turned into parallel light by the projection lens 32, passes through the beam splitter 92, and enters the alignment mark 41M. The alignment mark 41M is a transmissive zone plate that functions as a convex lens to focus light on the point Q. The wafer alignment mark 41W is a reflective zone plate that functions as a convex mirror that focuses the light focused on the point Q onto the detection surface 90 of the sensor 38.

Under such an arrangement, when the wafer 2 is laterally displaced by ΔδW with respect to the mask l, the positional displacement Δδ of the center of gravity of the light amount on the detection surface 90 is expressed as follows.

It will be doubled. At this time, Δδ is proportional to Δσ, as is clear from the formula, and the resolution of the sensor is 091μ.
If there are m, the detected positional deviation amount Δσ is 0.001
It has a position resolution of μm. If object 2 is moved based on the positional deviation Δσ determined in this way, object 1 and object 2 can be aligned with high accuracy.

The mask lens A2F method is a method in which gratings or grating lenses for input and output are created on the mask surface, and are as follows.

As shown in FIG. 8, the light beam 47 incident on the first pattern 42 in of the first surface (which is a mask) forms a predetermined angle with the normal to the second surface 2 (which is a wafer), and It faces surface 2, is specularly reflected by second surface 2, and passes through second pattern 42° ut on first surface l. At this time, the second pattern 5 on the first surface serves to guide the emitted light beam 46 in the direction of the light spot position detection sensor 39, but it also serves to guide the emitted light beam 46 in the direction of the light spot position detection sensor 39. I can grasp it.

If, for example, a -dimensional light spot position detection sensor is placed at an appropriate position, it is possible to detect a change in the position i of the light flux, so the present system can be used as is. However, if the light receiving lens 36 is used, the following advantages arise. In other words, due to physical optics, the light beam is emitted in a somewhat divergent manner and the beam diameter tends to be large (so if the light is focused by the light receiving lens and the sensor 39 is installed at the energy position, it becomes a system that detects only the angle of the light beam, and the light receiving lens and sensor is an integral structure and is not affected by positional deviation even if the sensor is misaligned in the direction perpendicular to the optical axis of the lens.However, even if the sensor cannot be installed at the focal position due to various reasons, the effect of positional deviation can be ignored. Since this is sufficiently practical, there is no need to limit the sensor position to the focal position of the light receiving lens.

Further, in FIG. 8, the amount of movement S of the sensor surface spot with respect to the unit interval amount is given by:

For the reasons stated above, the absolute distance between the mask and the wafer can be measured. Therefore, for example, if a wafer is supplied while a mask is set, and the wafer enters a gap of 100 μm, which is larger than the desired spacing of 30 μm, the value of the mask wafer gap of 100 μm can be detected with high accuracy. Based on this length measurement value, the desired mask wafer spacing of 30 μm can be set in one go. This enables high-speed gap spacing setting.

Next, this embodiment will be explained using FIGS. 1(a), (b), and (c).

The light beam emitted from the alignment pickup head 24 is irradiated onto the mark 20 on the mask l and the wafer 2, and the reflected or diffracted light is emitted to the alignment pickup head 24 again. The alignment pickup head is attached to the stage 21 and is configured to be able to freely move two-dimensionally according to the alignment area, and is controlled by the stage control section 22. At this time, the stage 21 is guided by a super flat base plate 23, and is designed so that no picking or yawing occurs. The stage control unit 22 drives the stage 21 at the start of alignment and interval control to move the head 24 to a pre-stored position for illuminating and detecting the evaluation marks 20 on the mask and wafer. Furthermore, Fig. 1(a)
(b) is a schematic diagram showing a moving mechanism including the stage 21 and its surroundings. The moving mechanism will be explained in detail. FIG. 1(C) is a detailed diagram of the stage section and the stage controller section. The alignment pickup head 24 is attached to a clamper part 27 for pressing the super flat surface 10 on the support body 26 having the super flat surface 10 against the super flat base plate 23 with a constant pressure, and the super flat base 23 is attached to the upper part of the alignment device main body. It is posted through. The clamper part 27 is connected to a movable support portion 28 on the two-dimensional movable stage 21 and a parallel plate spring 30.
connected through. The stage 21 includes a base portion 21
B, x-direction sliding section 21X,) r-direction sliding section 21
The id part 21 guides the YSx+y bidirectional slide.
A slide portion 21X is provided on the G1 base portion 21B.

Drive source 21 that drives 21Y in the X direction and the y direction, respectively.
Consists of MX and 21MY. The operations of the drive sources MX and MY are controlled by the controller 22 to move the head 24 in each direction and position it at a predetermined position. The amount of movement of each stage is measured using laser length measuring devices 29X and 29Y, respectively.
The data is measured precisely by the controller 22.
Based on this, the controller 22 controls the head 2.
Detects the current position of 4 and moves the drive source MX to the specified position.
, MY, the position of the head 24 is precisely controlled. After the detection position is moved, the lateral shift and spacing are detected as described above, and based on the detection results, the wafer stage 25 is moved in the direction of lateral shift and spacing error correction, and after completing the alignment and spacing control, the head 2
4 returns to its original position so as not to interfere with mask and wafer exposure. The alignment pickup head 24 incorporates a lateral shift detection system, an interval detection system, and a light projection system, and the light beam emitted from the light source 31, specifically, the semiconductor laser, is transmitted through a collimator lens 32, a projection lens 33, and a projection mirror 34. is projected onto the evaluation mark 20 via. The light beam emitted from the mark is guided to a detection system by a detection lens 36, split by a half mirror 37, and enters a lateral shift detection light receiving element 38 and an interval detection light receiving element 39, and becomes respective signals. Incidentally, the light emitting and light receiving window 35 of the alignment pickup head 24 is provided with a filter to prevent light from the exposure light source from passing therethrough.

As shown in FIG. 2, evaluation marks include a mark 41M for lateral shift detection and a mark 42 for distance measurement on the mask.
tn and 42 out are provided adjacent to each other.

Mark 41 is placed on the wafer at a position corresponding to mark 41M.
W is provided.

In this embodiment, the projection light 47 is designed to be parallel to the evaluation mark, and is simultaneously projected as the lateral shift detection mark 41M and the distance measurement mark 42.1 in the projection area 43. For this reason, the light projecting means for lateral shift detection and distance measurement are configured in one system.

As described above in the dual power grating method, the lateral shift detection system uses a wafer in which the arc 41M on the mask surface l has a light condensing function, and the condensed point is imaged at a position conjugate with the detection surface. Detection is performed by magnifying the lateral shift on the detection surface via the mark 41W. Light receiving lens 36
constitutes a relay lens system that relays the imaged point by the wafer mark 41 to the light receiving element 38 for lateral shift detection. FIG. 3(a) shows this system in terms of lens power arrangement.

On the other hand, the distance measurement system uses the mask lens A"F as described above.
The parallel incident light passes through the incident mark 42 In for measuring the spacing on the mask surface, is diffracted, the optical path is bent, is specularly reflected on the wafer surface 2 (no mark), and is reflected on the mask surface corresponding to the mask wafer spacing. Emission mark for distance measurement 42゜u
This constitutes a system in which the light is projected onto a predetermined area on t, exits the mask surface at an angle corresponding to the distance, and is guided onto the distance measuring light-receiving element 39.

FIG. 3(b) shows this system using a lens power arrangement similar to the lateral shift detection system.

The detection lens 36 of this embodiment is the same as the condensing lens in FIG. 3(b) and the relay lens in FIG. 3(a).

FIG. 4 shows a second embodiment according to the present invention, in which the methods of the lateral deviation detection system and the interval measurement system are the same as in the second embodiment, but a pattern mirror is used to divide the lateral deviation detection system and the interval measurement system. By using this method, the separation of both systems was carried out efficiently.

In this example, by slightly shifting the mark emission angles of the lateral shift detection system and the distance measurement system, the light beams of both systems form a spatial arrangement, and only the area on that surface where the distance measurement system light beam passes is a mirror surface. The two are separated. FIG. 5 shows an example of the mirror surface. When the incident angle to the light receiving lens system is shifted by about 4" in the plane orthogonal to the detection direction in the detection system and the distance measurement system, and the area where the light beams of both systems exist is separated on the pattern mirror surface 53, the lateral shift is detected. If the moving range of the light beam of the detection system in the practical range corresponds to each dynamic range, and the moving range of the light beam of the detection system in the practical range is 51a to 51n at intervals of 50a to 50, then as shown in FIG. The region is indicated by a dotted line, and includes the light beam regions 51a to 51n of the distance detection system, and includes the light beam region 5 of the lateral shift detection system.
A region 52 that does not include 1a to 51n is a mirror surface.

Note that the lateral shift detection system and the interval detection system are not limited to the dual power grating method and the mask lens A2F method (but may also be a combination of other methods).

〔Effect of the invention〕

As explained above, by configuring the lateral deviation detection system and the spacing measurement system as the same head and sharing part of the light emitting and receiving systems, it is possible to simultaneously evaluate the spacing control at the lateral deviation detection position using the same system. This enables highly accurate alignment for any circuit size and any process.

Furthermore, the device can be made more compact, reducing costs and setting errors in both systems.

[Brief explanation of the drawing]

FIG. 1 is a first embodiment of the present invention; FIG. 2 is an explanatory diagram of alignment mark arrangement, projection, and emitted light; FIG. 3 is a power arrangement diagram of a lateral shift detection system and an interval detection system;
Fig. 4 shows the second embodiment of the present invention, Fig. 5 shows the configuration of the pattern mirror, Fig. 6 shows the basic type of the lateral shift detection system, Fig. 7 shows the basic principle of the interval detection system, and Fig. 8 shows the basic principle of the spacing detection system. The basic type of the spacing detection system, FIG. 9 is an example of conventional lateral shift detection, FIG. 10 is a diagram explaining the principle of FIG. 9, and FIG. 11 is an example of conventional spacing detection. In the figure, l ・・・・・・・・・・・・・・・・・・・・・・・・
・・・Mask 2 ・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・Wafer 21 ・・・・・・・・・
・・・・・・・・・・・・・・・・・・Pickup stage 22・・・・・・・・・・・・・・・・・・
・・・・・・・・・Stage controller 23 ・・・
・・・・・・・・・・・・・・・・・・・・・Super flat base plate 24・・・・・・・・・
・・・・・・・・・・・・・・・Pickup head 25・・・・・・・・・・・・・・・・・・・・・
...Wafer chuck 31...
・・・・・・・・・・・・・・・・Light source 32・・・・
・・・・・・・・・・・・・・・・・・・・・Collimator lens 33・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・Light projection lens 34 ・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Mirror 3
5・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・−・・・・・・Filter 36...
・・・・・・・・・・・・・・・・・・・・・・・・
......... Light receiving lens 37...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Half mirror-38・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...... Lateral shift detection detector 39 ...
・・・・・・・・・・・・・・・・・・・・・・・・
...... Interval measurement detector 40 ...
・・・・・・・・・・・・・・・・・・・・・・・・
......Exposure area 41 ......
・・・・・・・・・・・・・・・・・・・・・・・・
... Lateral shift detection mark 42 ...
・・・・・・・・・・・・・・・・・・・・・・・・
...... Interval detection mark 43 ......
・・・・・・・・・・・・・・・・・・・・・・・・
......Projection light area 47...
・・・・・・・・・・・・・・・・・・・・・・・・
...Projection light direction 49...
・・・・・・・・・・・・・・・・・・・・・・・・
・・Scribe line 50・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...Light flux area 51 for interval detection ......
・・・・・・・・・・・・・・・・・・・・・・・・
...Light flux area 52 for lateral shift detection...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・Pattern Mira part 53・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
......Total pattern mirror 60...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・Wafer 62・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・Wafer table 64・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・Micro positioner-68・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・Mask 72・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・Light
Source 74・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ Half mirror 7
6,80・・・・・・・・・・・・・・・・・・
・・・・・・・・・Lens 78・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・Focusing point 82・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・Photodetector 84・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・Control circuit 9
0 ・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Sensor surface 92・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・Beam splitter-95
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ Main body 96...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・Mask Chuck 97・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・Mask membrane Ll, L2...
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・Lens M・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
Mask W・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Wafer S
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・This is the sensor side. Pw ~

Claims (4)

[Claims] (1) means for irradiating a light beam toward a first object and a second object to be aligned, which are arranged facing each other, and a light beam irradiated by the irradiation means and emitted from the first and second objects; means for detecting a distance between the first and second objects by detecting one light beam; and detecting a second light beam different from the first light beam irradiated by the irradiation means and emitted from the first and second objects. By doing so, the means for detecting lateral displacement of the first and second objects, and at least a portion of each of the irradiation means, the interval detection means, and the lateral displacement detection means are capable of irradiating and detecting predetermined portions of the first and second objects. A position detection device characterized by having a moving means for integrally moving the device to a certain position. (2) a single irradiation means that irradiates a light beam toward a first object and a second object to be aligned, which are arranged facing each other; By detecting the first light beam emitted from the first
and a means for detecting the distance between the second objects, and a second light beam irradiated by the irradiation means and emitted from the first and second objects by detecting a second light beam different from the first light beam emitted from the first and second objects. 1. A position detection device comprising: means for detecting lateral displacement of. (3) means for irradiating a light beam toward a first object and a second object to be aligned, which are arranged facing each other, and a light beam irradiated by the irradiation means and emitted from the first and second objects; means for detecting the distance between the first and second objects by detecting one light beam; and a second light beam different from the first light beam irradiated by the irradiation means and emitted from the first and second objects. and a single light-receiving optical system that guides the first and second light beams to the distance detection means and the lateral deviation detection means, respectively. A position detection device characterized by: (4) A light beam is irradiated toward a first object and a second object to be aligned, which are arranged facing each other, and the irradiation light beam is deflected in two different directions by the first object and the second object. A position detection method characterized in that the distance and lateral shift between the first and second objects are respectively detected by dividing the light beam into two light beams and detecting each of the light beams.