JPH0412523A - position detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a position detection device, and for example, in an exposure apparatus for manufacturing semiconductor elements, the present invention relates to a position detection device that detects a position on a first object surface such as a mask or a reticle (hereinafter referred to as "mask"). When exposing and transferring a fine electronic circuit pattern formed on a second object surface such as a wafer, the distance between the mask and wafer is measured and controlled to a predetermined value, and the relative surface of the mask and wafer is Positioning within (
The present invention relates to a position detection device suitable for performing alignment.

(Prior Art) Conventionally, in exposure apparatuses for semiconductor manufacturing, relative alignment between a mask and a sea urchin has been an important element for improving performance. Particularly in alignment in recent exposure apparatuses, alignment accuracy of, for example, submicron or less is required due to the high integration of semiconductor devices.

At that time, the distance between the mask and the wafer is measured with a surface distance measuring device, etc., and after controlling the distance to a predetermined distance, position information obtained from a so-called alignment pattern for positioning provided on the mask and wafer surfaces is measured. This is used to perform alignment on both sides. As an alignment method at this time, for example, the amount of deviation between both alignment patterns is detected by performing image processing, or alignment method as proposed in U.S. Pat. This is carried out by, for example, using a zone plate as a pattern, irradiating the zone plate with a light beam, and detecting the focal point position of the light beam emitted from the zone plate on a predetermined surface.

FIG. 11 is a schematic diagram of a conventional position detection device using a zone plate.

In the same figure, a parallel light beam emitted from a light source 72 passes through a half mirror 74 and is condensed at a condensing point 78 by a condensing lens 76, after which it is placed on a mask alignment pattern 68a on the surface of a mask 68 and a support base 62. The wafer alignment pattern 60a on the surface of the wafer 60 is irradiated. These alignment patterns 68a and 60a are composed of reflective zone plates, and each form a focal point on a plane perpendicular to the optical axis including the focal point 78. At this time, the amount of deviation of the focal point position on the plane is detected by guiding the light onto the detection surface 82 using the condenser lens 76 and the lens 8o.

Based on the output signal from the detector 82, the control circuit 8
4 drives the drive circuit 64 to position the mask 68 relative to the wafer 60.

FIG. 12 is an explanatory diagram showing the imaging relationship between the light beams from the mask alignment pattern 68a and the wafer alignment pattern 60a shown in FIG. 11.

In the figure, a part of the light beam diverging from the condensing point 78 is diffracted by the mask alignment pattern 68a,
A focal point 78a indicating the mask position is formed near the focal point 78. Further, the other part of the light beam passes through the mask 68 as zero-order transmitted light and enters the wafer alignment pattern 60a on the surface of the wafer 60 without changing its wavefront. At this time, the light beam is diffracted by the wafer alignment pattern 60a, and then passes through the mask 68 again as zero-order transmitted light, condensing near the converging point 78, and changing the wafer position.Concentrating point 78b
form. In the figure, when the light beam diffracted by the wafer 60 forms a condensing point, the mask 68 simply acts as a transparent state.

The position of the focal point 78b by the wafer alignment pattern 60a formed in this way is determined according to the amount of deviation Δσ of the wafer 60 from the mask 68 in the direction (lateral direction) along the mask/wafer surface. A deviation amount Δ0 of an amount corresponding to the deviation amount Δσ along a plane orthogonal to the optical axis including
’.

FIG. 13 is a schematic diagram of an interval measuring device proposed in Japanese Patent Application Laid-open No. 61.111402. In the figure, a mask M as a first object and a wafer W as a second object are arranged facing each other, and a light beam is focused on a point Ps between the mask M and the wafer W by a lens L1.

At this time, the light beam is reflected on the mask M surface and the wafer W surface, and passes through the lens L2 to points P, , p on the screen S surface.
It is convergently projected onto M. The distance between the mask M and the wafer W is measured by detecting the distance between the focal points P, , pM of the light beam on the screen S surface.

Since the devices shown in Figs. 11 and 13 have completely different configurations, both the relative direction of the first object and the second object in the opposing direction (spacing direction) and in the direction perpendicular to the opposing direction (lateral direction, in-plane direction) In order to detect the positional relationship, it was necessary to separately provide a lateral direction (in-plane direction) relative position detection device and a distance measurement device.

For this reason, the entire device has tended to become larger and more complex.

Furthermore, in these devices, when the wafer is tilted, the luminous flux from the wafer fluctuates, resulting in a detection error.

Therefore, it is very difficult to precisely detect the positional deviation and measure the spacing of wafers with unevenness or warpage.

In response to this problem, the present applicant has proposed, in Japanese Patent Application No. 1-209928, a system that simplifies the entire device, is less susceptible to the influence of wafer tilt, and always detects lateral positional deviation and surface spacing with high precision. We are proposing a position detection device that can do this.

The position detection device of the same issue arranges a first object and a second object to face each other, and when detecting the relative positional relationship between the first object and the second object, the first object and the second object are a light source means for irradiating a light beam; and two light beams from the first object or the second object, the light source means emitting two light beams from the first object or the second object, the light beams being emitted from a predetermined surface according to the relative positional relationship along the direction perpendicular to the direction in which the first object and the second object face each other. a light detection means for detecting two light beams whose relative relationship of incident positions within the light beam changes;
The output signal from the light detection means is used to detect the first object and the second object.
position detection means for detecting a relative positional relationship in a direction perpendicular to the direction in which the objects face each other; and a signal based on at least one of the two light beams detected by the light detection means to detect the first object and the second object. and an interval detection means for detecting a relative positional relationship in opposing directions.

(Problems to be Solved by the Invention) Generally, when detecting the distance between the surfaces of a mask and a wafer and detecting the in-plane positional deviation between the mask and the wafer, the mask and the wafer are placed facing each other with a distance of 10 μm to 50 μm, for example. This is done in the following order:

(a) The distance between the mask and the wafer is set slightly larger than the proximity exposure interval (gap), and the wafer is moved to the next exposure wafer area (wafer stage movement).

This increases the distance between the mask and wafer by 10cm, which is close to the exposure cap.
This is to avoid this because if the wafer stage is moved by 5 degrees by ~20 μm, the wafer is not completely flat but has irregularities, and if the mask surface is inclined, it may come into contact with the mask.

(b) Detect the surface distance between the mask and the wafer. For example, the method proposed in Japanese Unexamined Patent Publication No. 2-1512 is used.

(c) The wafer is moved in the spacing direction based on the detected value of the spacing between the mask and the wafer so that the spacing between the mask and the wafer is the same as that at the time of exposure.

(d) Detecting the in-plane positional deviation between the mask and the wafer with the mask and wafer spacing set at the time of exposure. For example, the method proposed in the above-mentioned Japanese Patent Application Laid-Open No. 2-1512 is used. Then, adjust the mask and wafer so that there is only the positional difference between them.

(e) The circuit pattern on the mask surface is exposed and transferred onto the eight surfaces of the sea urchin by exposing to X-rays.

1) Move the mask and wafer a little further away from the exposure cap and move the wafer stage to the next exposure wafer area.

Returning to step (a) below, surface spacing detection, misalignment detection, and exposure are repeated one after another.

In such an apparatus, an AF alignment mark for detecting the distance between surfaces and an AA alignment mark for detecting positional deviation are provided on the mask surface. Also, there is A on the sea urchin eight side.
The A alignment mark is provided opposite the AA alignment mark on the mask surface.

The light beam passing through the AA alignment mark is detected by the AA sensor to detect positional deviation, and the AF sensor detects the light beam passing through the AF alignment mark to detect the surface distance. In the embodiment, a line sensor is shown, but an area sensor (two-dimensional) may also be used.

Figure 6 (A) and (B) show the AF incident on the AF line sensor 42 and the AA Klein sensor 4 surface at this time.
FIGS. 7A and 7B are explanatory diagrams schematically showing the spot states of the light flux and the AA light flux, and FIGS. 7A and 7B are explanatory diagrams showing the relationship between the mask M and the wafer W at this time.

FIG. 6(A) shows the state when the mask M and the wafer W have an exposure gap δ1 as shown in FIG. 7(A).
FIG. 6(B) shows a state where the mask M and the wafer W have a face-to-face distance detection gap δ2 as shown in FIG. 7(B).

For example, δ1 = 10 μm to 70 μm, δ2 = δ1 + α (α
210 μm to 50 μm), 61220
If it is μm, δ2=70 μm.

The characteristic feature in Figures 6 (A) and (B) is δ2
〉From δ1, A on the AA line sensor surface in Figure 6 (A)
Spots 43 and 44 of the A light beam are determined by setting the focal point and interval between the mask and the zone plate on the wafer surface so that the best focus is achieved during the exposure gap. Therefore, the spot diameter on the four surfaces of the AA Klein sensor becomes a minimum sharp image. On the other hand, the spot of the AF light beam on the 4th surface of the AF line sensor corresponds to the sequence (b) above when the distance between the mask and the wafer is larger than the exposure gap. AF is set so that it can be detected.
It is not incident on the 4th side of the cylindrical sensor.

Further, when detecting the distance between surfaces as shown in FIG. 6 CB'), spots 45 and 46 of the AF light beam are incident on the AF silhouette sensor 4 surface in a sharp shape. However, if there is a large gap between the mask and the wafer on the AA Klein sensor 4 surface, the convergence state of the spot on the AA Klein sensor 4 surface changes as shown in Figure 7 (B), resulting in so-called day focus. A similar state occurs, and the spot 43'44' is expanded as shown by the dotted line in FIG. 6(B). For this reason, as shown in FIG. 6(B), the AF line sensor 42
There is a problem in that a part of the spots 43', 44= of the A light beam mixes in and becomes noise, resulting in a detection error.

In this way, the position detection device proposed in Japanese Patent Application No. 1-209928 is capable of detecting misalignment between a mask and a wafer and detecting the surface distance using a detection means having one light projecting means and two sensors. However, when detecting the distance between surfaces, unnecessary light for detecting positional deviation may enter the AF line sensor, creating noise and reducing the accuracy of detecting the distance between the surfaces.

The present invention effectively prevents unnecessary light for detecting positional deviation from entering the AF line sensor and causing noise when detecting the distance between the surfaces of the mask and the wafer, and improves both surface distance detection and positional deviation detection with high accuracy. The purpose of the present invention is to provide a position detection device that can perform the following tasks.

(Means for Solving the Problems) The position detection device of the present invention has a first object and a second object arranged facing each other.
Providing an AA alignment mark on each object for detecting the relative in-plane positional deviation between the two using an AA sensor, and detecting the relative inter-plane distance between the two on the first object using an AF sensor. An AF alignment mark is provided, and when detecting the relative spacing between the first object and the second object, the relative in-plane positional relationship between the two objects is determined so that the noise light from the AA alignment mark is detected by the AF alignment mark. After being displaced by a predetermined amount in a direction that does not enter the sensor, the light beam from the light source means is made to enter the AF alignment mark on the first object, and the light beam from the AF alignment mark is reflected on the second object surface to form a predetermined surface. a relative in-plane positional deviation between the first object and the second object; When detecting, the light beam from the light source means is made incident on a predetermined surface after passing through the AA alignment marks of both the first object and the second object, and the position of incidence on the predetermined surface is determined by the AA alignment mark. The present invention is characterized in that it has a position detecting means for determining the position by detecting it with a sensor.

In particular, in the present invention, when detecting the relative spacing between the first object and the second object, the relative in-plane positional relationship between the two objects is determined in the alignment direction of a single mark among the AA alignment marks. The feature is that the adjustment is performed after the adjustment is made so that the length is shifted by 1/2 or more.

(Embodiment) Fig. 1 is a perspective view of essential parts of an embodiment of the present invention, Fig. 2, Fig. 3
The figure is an enlarged explanatory view of a part of FIG. 1, and FIGS. 4 and 5 are explanatory views of the principle of positional deviation detection and surface distance detection according to the present invention.

In the figure, reference numeral 1 denotes a light source, which is comprised of a light source that emits a coherent light beam such as a semiconductor laser He-Ne laser, an A laser, a light source that emits a non-coherent light beam such as a light emitting diode, or an X-ray light source. 2 is a collimator lens, which converts the light beam from the light source 1 into a parallel light beam, adjusts the diameter of the light beam with a slit 3, passes it through a λ/4 plate 4,
The light is made incident on the lens system 5. The lens system 5 adjusts the incident light beam to a desired beam diameter, and then reflects it with a mirror 6 to make it resistant to Xr.
AA alignment mark (hereinafter referred to as "FAA mark") 20M for detecting positional deviation on the surface of the mask 18 as the first object by passing through the ay window 7 (when Xray is used as the light source), or for detecting the distance between surfaces. It is made incident on the AF alignment mark (hereinafter referred to as rAF mark) 21M.

The AA mark 20M and the AF mark 21M are provided at four locations around the mask 18. A wafer 19 is a second object, and an AA mark 20W to be aligned with the mask 18 is provided on the surface of the wafer. The AA marks 20M, 20W and the AF mark 21M are composed of physical optical elements such as one-dimensional or two-dimensional zone plates.

Reference numeral 10 denotes a light receiving lens, which focuses the diffracted light 16 of a predetermined order that has passed through the AA mark 20M and AF mark 21M on the surface of the mask 18 onto the surface of the light receiving means 11. The light receiving means 11 is constructed by providing two line sensors, an AA line sensor 12 for detecting positional deviation and an AF line sensor 13 for detecting surface distance, on the same substrate.

FIG. 2 is an explanatory diagram of AA marks 20M, 20W and AF mark 21M provided on the mask 18 and wafer 19 surface.

FIG. 3 shows the optical path of the light flux through the mask 18 and each mark on the wafer 19 surface. AA mark 20M has two AA marks 20M1 and 20M2, AA mark 20W has two
AA mark 20W1.20W2, AF mark 21M
consists of two AF marks 21M1, 21M3 for incidence and two AF marks 21M2, 21M4 for exit. Note that no AF mark is provided on the surface of the wafer 19, and light that is zero-order reflected (regularly reflected) on the surface of the wafer 19 is used.

There is one set of AA marks 20M1 and 20W1, and one set of AA marks 20M2 and 20W2, and the two luminous fluxes 1 incident on each AA mark 20M1 and 20M2.
Two diffracted lights by each mark of 5 (hereinafter referred to as "FAA diffracted lights")
That's what it means. )26-1.26-2 is A in response to the positional shift.
It is set to move on one side of the A-shiline sensor. Also, the light beam 15 incident on the AF marks 21M1 and 21M3 is reflected by the wafer 19 surface and the AF marks 21M2.21
Two diffracted lights (hereinafter referred to as "rAF diffracted lights") 27-1 and 27-2 emitted from the M4 are set to move on one surface of the AF silhouette sensor in accordance with the surface spacing. Incidentally, in FIG. 3, each incident light beam 15 is a ray in one common beam emitted from the light source 1.

The position detection device of the present invention detects the surface distance between the mask and the wafer by shifting the positions of both the mask and the wafer by a predetermined amount according to the dimensions of the AA mark, and then refers to the surface distance detection result to detect the distance between the mask and the wafer. Although the present invention is characterized by detecting positional deviation, the principles of the positional deviation detection method and surface distance detection method according to the present invention will be explained first.

First, a method for detecting the relative position between the mask 18 and the wafer 19 in the present invention will be explained with reference to FIG.

FIG. 4 shows an expanded view of the optical path when viewed from a direction perpendicular to the position detection direction (alignment direction) and perpendicular to the surface normal of the mask 18 and wafer 19 in FIG. Elements on the right side of the figure that are the same as those shown in FIGS. 1 to 3 are given the same reference numerals. Furthermore, although the incident light beam is reflected and diffracted at the AA mark on the surface of the wafer 19, the figure shows an equivalent state of transmitted diffraction.

20M1 is an AA mark provided on the mask 18, and 20W1 is an AA mark provided on the wafer 19, forming a single mark for obtaining the first signal. 20M2 to mask 18, 20
W2 is an AA mark provided on the wafer 19, forming a single mark, and is used to obtain a second signal.

26-1.26-2 is the 1st. AA diffracted light for second signal,
32 is a primary focus plane, which is in a conjugate relationship with the light receiving means 11 with respect to the light receiving lens 10.

Now, calculate the distance from the wafer 19 to the primary focus plane 32,
Distance g between mask 18 and wafer 19, AA mark 20
The focal lengths of M1 and 20M2 are respectively fal + f a2,
The amount of relative positional deviation between the mask 18 and the wafer 19 is ΔG,
The amounts of displacement from the coincident state of the luminous flux gravity centers of the AA diffracted lights 26-1 and 26-2 at this time are defined as Sl and S2, respectively.

Note that the light beam 15 incident on the mask 18 is assumed to be a plane wave for convenience, and the symbols are as shown in the figure.

Displacement amount S1 of the center of gravity of the luminous flux of the AA diffracted light 26-1.26-2
and S2 is the focus Fl of AA mark 20M1.20M2,
It is determined geometrically as the intersection of the primary focus plane 32 and a straight line connecting F2 and the optical axis centers of the AA marks 20W1 and 20W2. Therefore, in order to make the displacement amounts S, S2 of the luminous flux gravity center of each AA diffracted light beam in opposite directions with respect to the relative positional deviation between the mask 18 and the wafer 19, the AA mark 20W1
．． This can be achieved by reversing the signs of the optical imaging magnifications of 20W2.

Also, quantitatively s,=-L'-f"++gΔσ: aI-g s2=-L-f...+gyu.

−ag, and the deviation magnification is β2=S2/Δσ, β2=S2/
It can be defined as Δσ. Therefore, in order to make the shift magnification the opposite sign, it is sufficient to satisfy the following. Among these, one of the practically appropriate configuration conditions
As one example, there is the condition L)lf, l+f-+/f-2<0 Ifa>g+f-21>g. That is, AA mark 20M1.20M2,
The distance to the primary focus plane 32 is increased relative to the focal length fal+fa2, the distance g between the mask 18 and the wafer 19 is decreased, and one of the AA marks is a convex lens and the other is a concave lens.

On the upper side of Fig. 4, the incident light beam is condensed by the AA mark 20M1, and before reaching the condensing point F, the AA mark 20W
1 is irradiated with a light beam, and this is further focused on a primary focus plane 32. The focal length fbl of the AA mark 20W1 is determined to satisfy the lens equation. Similarly, in the lower part of FIG. 4, the AA mark 20M2 changes the incident light flux into a light flux that diverges from the point F2 on the incident side, and this is focused on the primary focus plane 32 via the AA mark 20W2. . At this time, the focal path mtb2 of the AA mark 20W2 is determined to satisfy the ladder. Under the above configuration conditions, the imaging magnification for the condensed image of the AA marks 20W1, 20W2 is clearly positive as shown in the figure, and the direction of the shift amount Δσ of the wafer 19 and the light spot displacement position s1 of the primary focus plane 32 are opposite. Therefore, the deviation magnification β1 defined earlier becomes negative. Similarly AA mark 20
The imaging magnification of the AA mark 20W2 with respect to the point image (virtual image) of M2 is negative, the direction of the deviation amount Δ0 of the wafer 19 and the light spot displacement amount S2 on the primary focus plane 32 is the same direction, and the deviation magnification β2 is It becomes positive.

Therefore, for the relative positional deviation amount δ between the mask 18 and the wafer 19, the system of AA mark 20M1.20W1 and the system of AA mark 2
0M2.20W2(7) system AA diffraction light 26-1.26
The deviation amounts S, s2 of −2 are in opposite directions.

That is, the spot 30 on the primary focus plane 32 formed by diffraction of the pattern of the AA mark 20M1.20W1.
The distance between the spot 31 on the primary focus plane 32 formed by diffraction of the pattern of the AA marks 20M2, 20W2 changes depending on the amount of misalignment between the mask 18 and the wafer 19, and the distance between these two spots 30.31 is projected by the light-receiving lens 10 onto the AA silhouette sensor 1 of the light-receiving means 11. And 2 with AA line sensor 12
By detecting the light intensity of the two spots 30 and 31, the relative positional deviation between the mask 18 and the wafer 19 is detected.

In this embodiment, the wafer 19 is tilted (T) with respect to the mask 18.
int), the two spots 30 and 31 move on the primary focus plane 32 by the same amount in the same direction, so the spot interval remains unchanged, and as a result, no position detection error occurs. ing. The above is the configuration of the position detection means according to the present invention.

Note that although the embodiment has been shown in which the AA and AF sensors are provided on the same substrate surface, the AA sensor and the AF sensor may be provided on different substrate surfaces even if they are not on the same substrate surface.

It can also be used as a single sensor, AA and AF sensor.

Next, a method for detecting the surface distance between the mask 18 and the wafer 19 in the present invention will be explained with reference to FIG. In this figure, the same elements as those shown in FIGS. 1 to 3 are given the same reference numerals.

In this embodiment, the incident light 15 is transmitted to two AFs on the mask 18 surface.
It is made incident on mark 21M1 (21M3). AF
The light incident on the mark 21M1 (21M3) is diffracted by the mark, and, for example, the first-order diffracted light is separated from the mask 18 by the distance g1.
(g2) Specular reflection on the distant wafer 19 surface, mask 1
The light enters the AF mark 21M2 (21M4) on the 8th surface. The AF mark 21M2 (21M4) consists of a pattern in which the diffracted light is subjected to the same focusing effect as a lens.

Then, the light reflected by the wafer 19 is the AF mark 21M2.
(21M4) has an optical effect such that the exit angle of the emitted diffracted light changes depending on the incident position (pupil position of the grating area).

For example, when the distance between the mask 18 and the wafer 19 is g2, the AF diffracted light diffracted by the AF mark travels along the optical path shown by the solid line, passes through the light receiving lens 10, and forms two spots 51 and 52 on the surface of the AF silhouette sensor. form. Similarly, when the surface spacing is gl, the AF diffracted light diffracted by the AF mark follows the optical path indicated by the dotted line and forms two spots 53 and 54 on the surface of the AF silhouette sensor.

In this way, depending on the surface distance between the mask 18 and the wafer 19,
Since the distance between the two spots generated on the surface of the F-shiline sensor 1 changes, the distance between the mask 18 and the wafer 19 is detected by measuring the distance between the two spots at this time.

In addition, in this embodiment, as in the position detection method, even if the wafer 19 is tilted (Tint) with respect to the mask 18, the two spots move by the same amount in the same direction on the surface of the AF silhouette sensor 1, so the spots It has the advantage that no spacing is required, and as a result, no surface spacing detection error occurs. The above is the configuration of the surface distance detection means according to the present invention.

Next, the operation of specifically detecting the relative position between the mask and the wafer in the present invention will be described.

FIGS. 8 and 9 are explanatory diagrams of the AA mark and AF mark provided on the mask 18 and the wafer 19 surface. Figure 8 (A)
is the AA mark and AF when the position detection direction is taken as the X axis
FIG. 2 is a schematic diagram of the relative positions of marks viewed from a direction perpendicular to a mask surface and a wafer surface, and shows a case where in-plane signal detection is performed.

Figure 8 (B) shows the case where the positional relationship between the mask and the wafer is shifted in the X-axis direction by a distance Δ corresponding to the length of a single AA mark on the eight faces of the sea urchin. Indicates when to do so.

FIGS. 9(A) and 9(B) are perspective views of essential parts showing the mask 18 and the AA mark and AF mark on the wafer 19 surface. 8(A) corresponds to FIG. 8(A), and FIG. 8(B) corresponds to FIG. 8(B).

In the figure, 15 is the incident light, 20M1.20M2 is the AA mark on the mask 18 surface, 21M1 is the AF mark on the mask 18 surface, and 20W1.20W2 is the AA mark on the wafer 19 surface. Optical action is the 4th and 5th
This is the same line as explained in the figure.

In this embodiment, when detecting the relative position between the mask 18 and the wafer 19, first detect the position of the AA mark between the mask 18 and the wafer 19 as shown in FIGS. 8(B) and 9(B). The mask 18 is relatively shifted in the direction (X-axis direction) by at least 1/2 of the dimension (length) of the single mark (the figure shows a case where the single mark is shifted by a length Δ). The surface spacing between the wafer 19 and the wafer 19 is detected by the method shown in FIG.

At this time, the AA marks 20M1 and 20M2 correspond to a part of the AA mark 20W2 on the opposing wafer surface and a no mark (area where no mark exists), respectively. Therefore, no AA diffracted light is generated, and no part of the large blurred image of the AA diffracted light is incident on the AF line sensor surface. This allows S
It becomes possible to detect the surface spacing with a good /N ratio. In the present invention, even if noise light of about 1/2 is incident on the AF line sensor when the position is not even, it is possible to detect the position with relatively high accuracy. It is made to be at least 1/2 or more.

In this way, in the present invention, the AA for position detection is used when detecting the surface distance.
In order to prevent diffracted light from entering the AF line sensor as noise, the relative position of the mask and wafer is adjusted in the direction of detecting the position of the AA mark on the wafer surface by at least 172 times the length of a single AA mark. (Distance Δ/2) The wafer stage is shifted using a length measuring device.

Then, when detecting the in-plane position between the mask and the wafer, the value obtained by detecting the surface distance is used, and only the value obtained by moving the wafer stage is used when detecting the surface distance.

Move it in the ever stage x, y, z tertiary directions (in this example, the X direction) and return it to its original position, and then
After the A mark and the AA mark on the wafer surface are roughly aligned, the process shown in FIG. 4 is performed. In this way, highly accurate relative position detection between the mask and the wafer is made possible.

Next, a sequence for performing position detection in the present invention will be explained with reference to FIG.

FIGS. 10(A), 10(B), and 10(C) are all schematic views of the mask and wafer viewed from a direction perpendicular to each surface. In the figure, 91 is the circuit pattern area on the mask surface, 93
．． 934 are the mark areas of the AA mark and AF mark on the mask surface, each indicated by a solid line. 92 is a circuit pattern area on the wafer surface, and 941 to 944 are mark areas of AA marks on the wafer surface, each indicated by a dotted line.

For example, the sequence is as follows: (I) The spacing between the mask and the wafer is made slightly larger than the proximity exposure gap, and the wafer is moved to the next exposure wafer area.

(11) Detect the surface distance between the mask and the wafer. At this time, as shown in Figure 10 (B), the wafer is intentionally set in the XY plane by shifting the mask and wafer by a distance ΔX from the state where they almost match (because the state where they roughly match has been measured in advance by pre-alignment). mark areas 931 to 934, 94
Surface spacing is detected in a state in which the angles of ˜944 are rubbed.

At this time, the mark area 93. is the area on the wafer side of the AF mark. There are no patterns at the positions corresponding to the patterns 933 and 933, but there are no patterns at the positions corresponding to the patterns 932 and 934 (areas on the wafer surface projected perpendicularly to the mask surface from the AA mark and AF mark on the mask surface). There is a circuit pattern.

Therefore, depending on the presence or absence of a circuit pattern on the wafer surface, the presence or absence of unevenness on the wafer surface causes a difference in the absolute value of surface spacing detection. The amount of this difference is measured in advance as a representative value for each wafer process, prepared as a correction value, and used when detecting the surface spacing.

That is, if the surface spacing detection value when there is no circuit pattern on the wafers facing each other in the mark areas 931 and 933 is converted by adding or subtracting the value when there is a circuit pattern on the wafers in the mark areas 932 and 934 by a certain amount. good.

Further, as shown in FIG. 10(C), the wafer is intentionally shifted by a distance ΔY in the Y direction to detect the surface spacing. At this time the 10th
Contrary to the case in Figure (B), there is no pattern on the wafer opposite the mark areas 932 and 934;
．． ．． There is a circuit pattern on the wafer facing 933, and the surface distance detection corresponding to this pattern must be corrected.

Here, the distances ΔX and ΔY correspond to the distance Δ shown in FIG. 8(B) and FIG. 9(B), and this amount is, for example, AA mark 20
It is sufficient to shift the area size by at least 1/2 of the area size of M1.20M2.

In addition, when the wafer is shifted by a distance ΔX or a distance ΔY, the movement of the wafer stage is measured with a length measuring device, and the measurement is performed based on the value of the length measuring device.

(III) Furthermore, based on the detection of the surface spacing between the mask and the wafer, the wafer is moved in the plane (x, y directions) and in the spacing direction so as to maintain the surface spacing between the mask and the wafer at the time of exposure.

(rV) Detecting the in-plane position of the mask and wafer with the distance between the mask and wafer set at the time of exposure,
The wafer is rotated and moved in parallel so that the stock becomes completely zero in the plane.

(V) The circuit pattern on the mask surface is exposed to xm light and transferred onto the wafer surface.

(VT) The mask and wafer are separated slightly from the exposure gap,
Move the wafer stage to the next exposure wafer area.

Return to (I) below and repeat the same process.

(Effects of the Invention) According to the present invention, relative position detection regarding the interplanar distance and in-plane positional deviation between the first object and the second object can be performed using one light projecting means and one projector.
When using two light receiving means, by configuring each element as described above, it is possible to prevent the light for positional deviation detection from entering the AF line sensor as noise when detecting the surface distance between the first object and the second object. However, a signal with a high S/N ratio can be obtained, and it is possible to detect the interfacial distance with high illuminance.
A position detection device capable of detecting the in-plane positions of an object and a second object with high illuminance can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts of an embodiment of the present invention, and FIG. Figure 3 is an enlarged explanatory view of a portion of Figure 1; FIG. 5 is a diagram explaining the principle of positional deviation detection and surface spacing detection in the present invention, and FIG.
．． FIG. 7 is an explanatory diagram showing the state of the light flux incident on the surface of the light receiving means in a conventional position detection device; 9 is an explanatory diagram of the AA mark and AF mark provided on the mask and wafer surface according to the present invention, FIG. 10 is an explanatory diagram showing the relative positional relationship between the mask and the wafer, and 11. Figure 12. FIG. 13 is a schematic diagram of a conventional position detection device. In the figure, 1 is a light source, 2 is a collimator lens, 3 is a slit, 4 is a person/4 plate, 6 is a mirror, 10 is a light receiving lens, 1
8 is a mask, 19 is a wafer, 2°Ml, 20M2°20W1.20W2 is an AA mother, and 21M1 to 21M4 are AF marks.

Claims (2)

[Claims] (1) An AA alignment mark is provided on the first object and the second object arranged opposite each other to detect the relative in-plane positional deviation of both using an AA sensor, and An AF alignment mark is provided to detect the relative distance between the first and second objects using an AF sensor, and when detecting the relative distance between the first and second objects, the relative in-plane positional relationship between the two objects is determined. is displaced by a predetermined amount in a direction in which noise light from the AA alignment mark does not enter the AF sensor, and then the luminous flux from the light source means is directed to the AF sensor on the first object.
The light flux from the AF alignment mark is reflected by the second object surface to be incident on a predetermined surface, and the incident position on the predetermined surface is detected by the AF sensor. When detecting a relative in-plane positional deviation between the first object and the second object, the light beam from the light source means is connected to the AA of both the first object and the second object. A position detecting means configured to cause the beam to be incident on a predetermined surface after passing through an alignment mark, and to determine the position of incidence on the predetermined surface by detecting the position of incidence on the predetermined surface with the AA sensor. Detection device. (2) When detecting the relative spacing between the first object and the second object, the relative in-plane positional relationship between the two objects is determined by the AA.
2. The position detecting device according to claim 1, wherein the position detecting device performs the adjustment after adjusting the length of a single mark among the alignment marks to be shifted by 1/2 or more in the alignment direction.