JP3513304B2 - Position shift detection method and semiconductor device manufacturing method using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positional deviation detecting method and a semiconductor device manufacturing method using the positional deviation detecting method. For example, in an exposure apparatus for manufacturing a semiconductor element, a mask or a reticle (hereinafter referred to as "mask") or the like is used. 1 Fine electronic circuit pattern formed on the object surface
This is suitable for performing relative in-plane positioning (alignment) between the mask and the wafer when the exposure transfer is performed on the object surface.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus for manufacturing a semiconductor, relative alignment between a mask and a wafer has been an important factor for improving performance. In a typical DRAM of a semiconductor integrated circuit, a total overlay accuracy of about 1/3 to 1/4 of the minimum line width of a resolution pattern image is required. Particularly in the recent alignment of the exposure apparatus, alignment accuracy of 20 nm or less is required for high integration of semiconductors.

For example, the 1Gbit DRAM which is currently in the research level requires a total overlay accuracy of 40 nm to 50 nm,
The accuracy assigned to the positioning accuracy is 10 nm
To 15 nm.

Many exposure apparatuses are provided with alignment marks, so-called alignment marks, respectively on the mask and the wafer, and optically detect the positional deviation of each alignment mark, and based on the value, the mask and the wafer are aligned. Is being aligned. The method of detecting the alignment mark is to enlarge the mark optically.
Projected on a CCD for image processing, measuring the phase of the diffracted light using a linear diffraction grating for the mark, or using a zone plate for the mark and detecting the light diffracted by the zone plate on a predetermined surface. , There is a device that detects the positional deviation of the light.

Among these detection methods, the method using a linear diffraction grating or a zone plate as an alignment mark is characterized in that relatively high precision alignment that is resistant to a semiconductor process can be performed in the sense that it is hardly affected by defects in the mark. .

[0006]

Generally, in order to detect the relative positional shift between the mask and the wafer and to perform the alignment between them, the mask and the wafer should be spaced from each other within a predetermined range. After the control, the position information obtained from the sensor when the so-called alignment pattern for alignment provided on the mask and the wafer surface is used to perform both alignments.

At this time, if the distance between the mask and the wafer deviates from the predetermined range, the signal waveform obtained from the sensor is broken. In particular, when the distance between the mask and the wafer deviates significantly from the predetermined range, the detection signal obtained by the sensor changes greatly with respect to the change in the distance between the mask and the wafer, that is, the sensitivity increases, and the alignment accuracy increases. It is decreasing.

According to the present invention, the optical properties of the alignment marks provided on the first object (mask) and the second object (wafer) are appropriately set, and the irradiation condition of the light beam to the alignment mark and the light beam from the alignment mark are set. Even if the distance between the first object and the second object changes variously by appropriately setting the light receiving conditions of the sensor that receives the light, the relative positional deviation between the first object and the second object can be accurately performed. An object of the present invention is to provide a position shift detection method that can detect and perform highly accurate alignment, and a semiconductor device manufacturing method using the same.

[0009]

According to another aspect of the present invention, there is provided a positional deviation detecting method, wherein when a first object and a second object are opposed to each other to detect a relative positional deviation between them in a predetermined direction. A first zone plate having power in the direction of deviation detection is provided on the first object surface, and a second zone plate is provided on the second object, and a light beam is projected from the light projecting means onto the first object surface at an angle θ. When the light is irradiated with, the first zone plate transmits and diffracts the light, and the second zone plate reflects and diffracts the 110 light that has passed through the first object and the first object, and the second zone plate. Both of the 011 light reflected and diffracted by the first zone plate and transmitted and diffracted by the first zone plate are detected by the sensor at the light receiving angle θ which is the same angle as the light projecting angle θ, and the positional information of the spot on the sensor is used, Characterized by detecting the relative displacement of both

The invention of claim 2 is the same as the invention of claim 1.
It is characterized by setting each element to said light projecting angle θ is within the range of 85 degrees 5 degrees Te. Origination of claim 3
In the invention according to claim 1 or 2 , each element is set so that the incident angle of the 110 lights to the second zone plate is 0 ° ± 20 ° .

According to a fourth aspect of the present invention, there is provided a first method for detecting a positional deviation .
The object and the second object are arranged so as to face each other, the first and third zone plates are provided on the first object surface, and the second and fourth zone plates are provided on the second object surface. The positional information of the first light flux that enters the predetermined surface after passing through the first and second zone plates and the second light flux that enters the predetermined surface after passing through the third and fourth zone plates of the light flux The relative position of the first object and the second object using the position information.
When detecting the location shift, varying distance between the first and second objects
Of the first light flux and the second light flux on a predetermined surface with respect to
The first and fourth zones are set so that the shooting position changes with the same sensitivity.
For the zone plate, for the second and third zone plates
It is characterized by setting a negative refractive power .

The invention of claim 5 is the same as the invention of claim 4.
The first, fourth zone plate Te has a positive power, the second, third zone plate is characterized by having a negative refractive power. The invention of claim 6 is a contract
The invention of claim 4 or 5 is characterized in that the relative positional deviation between the first light flux and the second light flux is detected by using the distance between the incident positions of the first light flux and the second light flux on the predetermined surface.

According to a seventh aspect of the present invention, there is provided a first method for detecting a positional deviation .
The object and the second object are arranged so as to face each other, the first and third zone plates are provided on the first object surface, and the second and fourth zone plates are provided on the second object surface. When the light flux is applied to the first object surface at a projection angle θ, the positional information of the first light flux incident on the predetermined surface after passing through the first and second zone plates and the third and fourth light fluxes. The position information of the second light flux incident on the predetermined surface after passing through the zone plate is detected by the sensor at the light receiving angle θ which is the same angle as the light projecting angle θ, and the position information from the sensor is used to detect the first object. And the second object
When detecting the relative positional deviation, the so incident position in the first light beam and the predetermined surface of the second light flux with respect to the spacing variation between the first and second objects changes with the same sensitivity First
The first, fourth zone plate has positive, second and third zones
The plate is characterized by having a negative refractive power.

A first aspect of the present invention is a position shift detecting method .
The object and the second object are arranged so as to face each other, the first and third zone plates are provided on the first object surface, and the second and fourth zone plates are provided on the second object surface. Of the luminous flux of the first object and the second object at a predetermined interval, the first object
110 is transmitted and diffracted by the second zone plate, reflected and diffracted by the second zone plate, and 110 lights transmitted through the first object are condensed on a predetermined surface, and the first object and the second object are separated by the predetermined distance. The third zone plate transmits and diffracts the light and the fourth zone plate reflects and diffracts the light so that the 110 lights transmitted through the first object are condensed on a predetermined surface. An element is set, and the position information of the first light flux and the second light flux incident on a predetermined surface is used to detect the first object and the second object.
When detecting a relative positional shift, the first light flux and the second light flux are incident on the predetermined surface at the same sensitivity with respect to a change in the distance between the first and second objects, so that the incident positions change with the same sensitivity .
The first, fourth zone plate has positive, second and third zones
The plate is characterized by having a negative refractive power.

A method of manufacturing a semiconductor device according to the invention of claim 9
The method obtains the relative positional deviation between the first object and the second object by using the positional deviation detection method according to any one of claims 1 to 8.
Relative position detection between mask and wafer
Then, the pattern on the mask surface is formed on the wafer surface.
Transfer and then the semiconductor device through the development process
It is characterized by being manufactured. The position of the invention of claim 10
The position detection device is the position shift according to any one of claims 1 to 8.
Using the detection method, the relative position of the first object and the second object
It is characterized by seeking the deviation .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention, FIG. 2 is an explanatory view when an optical path of an optical system of a position shift detecting method of FIG. 1 is developed, and FIG. 2 is a schematic view of the alignment optical unit of FIG.

This embodiment shows a case where the present invention is applied to a semiconductor exposure apparatus using an X-ray as an exposure light source. In the figure,
Reference numeral 1 is a mask as a first object, and 2 is a wafer as a second object, and shows a case where both are aligned (positioned) using a light beam from the alignment optical unit 19.

In FIG. 1, the mask 1 is on the mask 1.
And alignment marks (first zone plates) 3L and 3R, which are Fresnel zone plates having power only in the X direction, which is the direction of detecting the positional deviation between the wafer and the wafer 2,
On the wafer 2, there are alignment marks 3L and 3R and alignment marks (second zone plates) 4L and 4R which are Fresnel zone plates having power only in the X direction to be positioned respectively.

Reference numerals 19L and 19R denote alignment optical units for detecting the positional deviation between the alignment marks 3L and 4L and the alignment marks 3R and 4R, respectively.
It is mounted on a stage that can move in the Y direction. Since the alignment optical units 19L and 19R have the same configuration, the alignment optical unit 19L will be described below.

10L is a semiconductor laser (light source),
The light emitted from the light source 10L passes through the projection lens 11L and the half mirror 13L, is condensed by the lens 14L, is reflected by the mirror 15L, and is reflected by the alignment mark 3 on the mask 1.
The L is irradiated with the projection angle θ. The alignment mark 3L has a light condensing function, and further emits outgoing light in the normal direction (−Z direction) of the mask 1 to produce the alignment mark 4L.
Is incident on. The mark 4L has a reflection type divergence action, and is diffracted at the same angle θ as the projection angle θ. The diffracted light passes through the mask 1 and is reflected by the mirror 15L,
The light passes through the lens 14L and the half mirror 13L and is focused on the sensor 12L. The sensor 12L uses a one-dimensional line sensor.

Incidentally, reference numeral 5 in FIG. 1 denotes a wafer chuck, which sucks the wafer 1, and 6 denotes an XYZ stage. The mask 1 and the wafer 2 are held at a predetermined interval by driving the Z stage.

Although not shown in FIG. 1, two alignment optical units 19L and 19L for detecting a deviation in the X direction are provided.
In addition to R, in the present embodiment, in order to detect the positional deviation in the Y direction, an alignment mark formed of a Fresnel zone plate having a power in the Y direction is provided on the scribe line between the mask 1 and the wafer 2, and the alignment mark There is a third alignment optical unit for mark detection.

The signal from the sensor in each alignment optical unit enters the CPU 16, the X direction deviation amount is obtained from the average value of the sensor outputs of the two X direction optical units, and the rotation amount is obtained from the difference between the outputs. The displacement amount in the Y direction is calculated from the sensor output of the alignment optical unit in the Y direction, and a signal is sent to the stage drive driver so as to align the mask 1 and the wafer 2. Each of the alignment optical units 19L and 19R is located at a position where X-rays, which are exposure light, are not shielded in the exposure area.

Next, the principle of the positional deviation detecting method in this embodiment will be described with reference to FIG. FIG. 2 shows a developed optical path that passes through the mask 1 and the wafer 2 in FIG. 1, and two light fluxes are shown because the light flux passes through the mask 1 twice.

Alignment mark 3 in this embodiment
(3L, 3R) and alignment mark 4 (4L, 4R)
The power distribution of is as shown in the figure. A light condensing surface 23 is condensed by the alignment mark 3 of the mask 1, diverged by the alignment mark 4 on the wafer 2, and the light (110 light) transmitted through the mask 1 is condensed.

Now, assuming that the focal length of the alignment mark 3 of the mask 1 is Fm and the focal length of the alignment mark 4 of the wafer 2 is Fw, the distance between the mask 1 and the wafer 2 is g, and the distance from the mask 1 to the light collecting surface 23. Is L, the position S1 of the condensing point of 110 light in the X direction on the condensing surface 23 is S1 = (1−L / (Fm−g)) depending on the shift amount x between the mask 1 and the wafer 2 in the X direction.・ X becomes (1).

On the other hand, the X-direction of the light (011 light) which is transmitted through the mask 1, diverged by the mark 4 on the wafer 2 and received by the mark 3 on the mask 1 on the light condensing surface 23. If the distance from the mask 1 to the light condensing surface 23 is L ′, the position S0 of the light condensing point is S0 = (L ′ / (Fw−g)) · x (2)

Further, 1 / (Fm-g) + 1 / L = -1 / Fw (3) is required as a condition for condensing 110 light on the condensing surface 23.

In this embodiment, L = 20 mm, g = 15 μm, and Fm = 213 μ so that the magnification for the positional deviation x between the mask 1 and the wafer 2 at the position S1 is 100 times.
m and Fw = −196 μm.

Next, referring to FIG. 3, the projection lens 11 in the alignment optical unit 19 (19L, 19R) shown in FIG.
(11L, 11R) and the light receiving lens 14 (14L,
14R) will be described.

The light 20 from the light source 10 is projected by the lens 11 for projecting light.
Is condensed once, reflected by the half mirror 13, and enters the lens 14. Here, the lens 11 and the lens 14
Is the condensing point 11 by the lens 11 with respect to the lens 14.
It is designed so that a is substantially conjugate with the mask 1. In this way, the projection beam spot on the mask 1 is made slightly larger than the alignment marks 3L, 3R. On the other hand, the light receiving side is designed so that the condensing surface 23 of 110 lights is relayed to the sensor 12 at the same magnification by the lens 14.

FIG. 4 shows a signal waveform obtained by the sensor 12 at this time. As shown in FIG. 4, the signal obtained by the sensor 12 is good. The deviation of the spot position of the light flux at this time is 107 times as sensitive as the deviation of the mask 1 and the wafer 2. Therefore, the position of the spot on the sensor 12 is measured, and the value obtained by dividing the value by 107 corresponds to the relative positional deviation between the alignment mark on the mask 1 and the alignment mark on the wafer 2.

This embodiment is characterized by the diffraction angle on the wafer 2 after being diffracted by the alignment mark 3 on the mask 1. For example, FIG. 5 is an optical path diagram used in a conventional positional deviation detection method. In the figure, the incident angle θm and the diffraction angle at the alignment mark of the mask 1 and the wafer 2 are shown. The incident angle to the mask 1 θin = 17.5 degrees and the exit angle from the mask 1 θout = 13 degrees. There is. In this case, considering the optical path lengths of the light incident on the alignment mark on the mask 1 and returning to the mask 1 after being diffracted by the alignment mark on the wafer 2, 110 light (ABC) and 011 light (AD)
E) is different.

FIG. 6 shows the case where the incident angle θin is fixed at 17.5 degrees and the diffraction angle θout at which the light vertically diffracted from the alignment mark on the mask 1 is diffracted by the alignment mark on the wafer 2 is changed. The phase difference between 011 light and 110 light is 15μm and 30μ between the mask and the wafer gap (GAP).
It is calculated for the case of m. Looking at this graph, the phase difference is about 2πrad at 30 μm GAP, while it becomes πrad at GAP of 15 μm.

That is, the disturbance of the signal waveform at GAP 15 μm is caused by the cancellation of the light because the 110 light and 011 light interfere with each other and the phase difference between them is π rad. further,
As one of the factors that the misregistration detection signal is fooled by the gap setting error between the mask 1 and the wafer 2,
One light beam is interfering with each other, and the phase difference between the two light beams changes due to the variation in the interval.

On the other hand, another important point in FIG. 6 is that when the diffraction angle is the same as the incident angle of 17.5 degrees, GAP
The phase difference will always be zero as the value changes. This is the same even when the incident angle is other than 17.5 degrees. Therefore, in this embodiment, the incident angle θin and the diffraction angle of the 110-light wafer-side alignment mark are set to be the same. As a result, the phase difference is set to zero, and as a result, it is possible to perform more accurate alignment with less influence of the gap setting error between the mask and the wafer.

Further, the alignment performance can be maintained at various exposure gaps. Furthermore, since the alignment performance does not change even if the projection angle is changed, the degree of freedom in design is increased in the alignment optical unit or when the alignment optical unit is incorporated in the exposure apparatus.

In the case of the present embodiment, the light beam is incident on the alignment mark at an incident angle θin of 17.5 degrees, is vertically diffracted by the mask alignment mark, and is diffracted by the wafer alignment mark at 17.5 degree, and the exit angle θout. 17.
Although it is set to 5 degrees, the arrangement pitch of the lattice elements in the Y direction (direction orthogonal to the position shift detection direction) in this case is set by setting the arrangement pitch of the alignment marks on the mask and the arrangement pitch of the alignment marks on the wafer to the same pitch p. Well, λ is the wavelength (785 nm is used) p = λ / sin
From (17.5 degrees), p = 2.61 μm.

Further, in the case of the present embodiment, the diffracted signal light is reflected by the half mirror 13L (13R) and returns to the light source, so that the stability of the light source is not deteriorated and the alignment marks 4L, 4R is arranged at a position eccentric in the X direction with respect to the marks 3L and 3R on the mask, and in the range where the positional deviation is detected, the emission part of the light source and the diffracted light are separated in the X direction, and the return light I try not to worry. Particularly, in the present embodiment, the incident angle θin is set within the range of 5 degrees to 85 degrees. Further, the angle at which 110 rays are incident on the second zone plate 4 is set within the range of 0 ± 20 degrees.

As described above, in the present embodiment, the positional deviation between the mask 1 and the wafer 2 is detected, and the alignment of both is performed with high accuracy.

FIG. 7 and FIG. 8 are schematic views of the essential portions of the second embodiment of the present invention, showing the optical paths of the method for detecting the positional deviation between the mask 1 and the wafer 2.

First, in FIG. 8, on the mask 1, there is an alignment mark (first zone plate) 30a consisting of a Fresnel zone plate having power only in the X direction on the scribe line, and the transmitted first-order diffracted light is collected. It is irradiated with light and is emitted in the normal direction (−Z direction) of the mask 1. Alignment mark (second zone plate) 30
b is provided on the scribe line on the wafer 2 and is composed of a Fresnel zone plate having a power only in the X direction, whereby reflected diffracted light is diverged.

Further, on the YZ plane, the light is diffracted at an angle different from the projection angle. The diffracted light passes through the mask and is focused on the sensor 12. Such a combination of zone plates (30a and 30b) that receives the convex lens action at the mask-side alignment mark 30a and the concave lens action at the wafer-side alignment mark 30b is hereinafter referred to as a convex-concave system.

Further, on the scribe lines of the mask 1 and the wafer 2, respectively, uneven alignment marks 30a,
An alignment mark (third zone plate) 31a and a alignment mark (fourth zone plate) 31b, which are Fresnel zone plates having power only in the X direction, are provided adjacent to the pair of 30b. The alignment mark 31a on the mask 1 gives a diverging action to the transmitted first-order diffracted light, and the alignment mark 31b on the wafer 2 gives a focusing action to the reflected diffracted light.

The combination of zone plates (31a and 31b) that receives the concave lens action on the mask side and the convex lens action on the wafer side in this manner is hereinafter referred to as a concavo-convex system.
The light that has passed through the uneven system is focused on the sensor 12 in the same manner as the light that has passed through the uneven system.

The above-mentioned light is first-order diffracted by the mask-side mark, first-order diffracted by the wafer-side mark, and transmitted through the mask (1
As described above, the light (10 light) is actually transmitted through the mask-side mark, first-order diffracted by the wafer-side mark, and then diffracted by the mask-side mark (011 light). Concentrate light at a position close to.

FIG. 7 shows the situation at this time. Reference numeral 23 denotes a (110 light) condensing surface. The focal lengths of the alignment marks 30a and 31a of the mask 1 are Fm1 and Fm2, respectively, and the alignment marks 30 of the wafer 2 are
If the focal lengths of b and 31b are Fw1 and Fw2, the distance between the mask 1 and the wafer 2 is g, and the distance from the mask 1 to the light condensing surface 23 is L, the shift in the X direction between the mask 1 and the wafer 2 is x. Thus, the positions S1 and S2 of the condensing points of the uneven light and the concavo-convex 110 light in the light converging surface X direction are respectively S1 = (1−L / (Fm1−g)) · x (4) S2 = (1-L / (Fm2-g)) x ... (5).

On the other hand, the positions S3 and S4 of the X-direction convex-concave and concave-convex 011 light condensing points on the condensing surface 23 are S3 = (L '/ (Fw1-g)). (6) S4 = (L ″ / (Fw2-g)) · x (7)

Here, L ′ and L ″ are the distances to the mask 1 and the position where the 011 light of the uneven system and the uneven system are condensed, respectively.

Further, as conditions for condensing 110 lights on the condensing surface 23, 1 / (Fm1-g) + 1 / L = -1 / Fw1 (8) 1 / (Fm2-g) + 1 / L = -1 / Fw2 (9) is required.

In this embodiment, L = 20 mm, g = 30 μm, and Fm1 = 228 μ so that the magnification with respect to the positional shift x between the mask at the position S1 and the wafer becomes −100 times.
m and Fw1 = −196 μm. On the other hand, position S2
As for the magnification of, the marks of various magnifications are prepared in advance so as to satisfy the equations 5 to 9, and the spot of the spot on the sensor is changed by the gap variation (GAP variation) between the mask and the wafer. A magnification is selected so that the amount of change including the sign is the same as that of the uneven system.

FIG. 9 shows a change in spot position per 1 μm of GAP when the magnification of 110 light in the concave-convex system is changed, and the variation becomes smaller as the magnification becomes lower. Since the spot change amount on the sensor per 1 μm of uneven GAP was 10 μm, the uneven system 110
The magnification of light was 70. At this time, the design value Fm2 of the focal lengths of the alignment marks 31a and 31b
Fw2 is -260 μm and 294 μm, respectively.

By using the alignment mark composed of the uneven and uneven zone plates, the mask 1 and the wafer 2 are
Was moved relative to the position deviation detection direction and the distance D between both spots was measured.
Was changed at a magnification of 167 times and the linearity was also good. Therefore, by measuring the spot distance D 1 on the sensor and dividing the distance by 167, a relative positional deviation detection signal between the mask 1 and the wafer 2 can be obtained.

As shown in FIG. 6, GAP is 30 μm.
In, the phase difference between 110 light and 011 light was 2π rad, and the waveform was good because it was an interference condition that mutually strengthened each other.

In this embodiment, when the GAP of the mask and the wafer are changed, the incident positions on the sensor surface of the first light flux due to the concave-convex system and the second light flux due to the concave-convex system are changed with the same sensitivity.

FIG. 10 shows how the positional deviation detection signal fluctuates when the GAP of the mask and the wafer change. As shown in the figure, even if the GAP fluctuates by 1 μm, the fluctuation amount of the positional deviation detection signal is 0.01 μm (10 nm) or less, and the positional deviation detection signal is stable.

FIG. 11 shows an alignment mark (30
a, 30b, 31a, 31b), the alignment optical unit changes when the alignment optical unit moves in the Y direction.
Even if it fluctuates by 0 μm, the change in the positional deviation detection signal is as small as 3 nm, and the alignment error due to the positioning setting error of the alignment optical unit can be reduced.

The alignment error caused by the fluctuation of the alignment optical unit is caused by the change of the light quantity ratio of 110 light and 011 light when the projection beam changes with respect to the alignment mark. Is also caused by unevenness of the film thickness of the alignment mark on the wafer side due to the semiconductor process. That is, if this embodiment is applied, the alignment error due to the influence of the semiconductor process can be reduced.

FIG. 12 is a schematic view of the essential portions of Embodiment 3 of the present invention.

In this embodiment, as in the first embodiment, the projection angle and the light reception angle are the same, and as in the second embodiment, a pair of a concave-convex system and a concave-convex system in which the spot variation amount on the sensor surface due to the interval variation is equal. The alignment mark of is used.

In the first embodiment, the mask 1 to the wafer 2 are used.
While the light diffracted perpendicularly to is used, in the present embodiment, the Y direction is slightly angled. With this configuration, the second-order diffracted light (dotted arrow in the figure) directly reflected and diffracted from the alignment mark 3 on the mask 1 is less likely to enter the sensor surface or the light source. Therefore, even when the diffraction efficiency of the reflected second-order diffracted light is relatively higher than the transmitted first-order diffracted light of the alignment mark 3 on the mask, which is the signal light, the positional deviation detection accuracy is maintained with high accuracy.

In the present embodiment, the light is incident on the alignment mark 3 on the mask 1 at an incident angle θin of 17.5 degrees, and is diffracted by the alignment mark 3 on the mask in the Y direction by 4.5 degrees.
The alignment marks 4 on the wafer 2 are diffracted at 17.5 degrees. In this case, the arrangement pitch of the lattice elements in the Y direction (the direction orthogonal to the position shift detection direction) is the arrangement pitch of the alignment marks 3 on the mask 1. Pm is different from the alignment pitch Pw of the alignment marks 4 on the wafer 2,
Is used as the wavelength (using 785 nm), the pitch Pm of the alignment mark 3 on the mask side is Pm = λ / ((s
From in (17.5 degrees) + sin (4.5 degrees)), Pm = 2.07 μm.

On the other hand, the pitch Pw of the alignment mark 4 on the wafer side is Pw = λ / ((sin (17.5 degrees) -s
in (4.5 degrees), Pw = 3.53 μm.

FIG. 13 shows the mask 1 in the apparatus according to the third embodiment.
And the signal waveform of the unevenness system when the alignment mark designed to be optimum when the GAP of the wafer 2 becomes 20 μm is measured. Even when a GAP different from the designed GAP by several μm to 10 μm as shown in FIG. 13 is used, the waveform for the alignment signal is not deteriorated and a good alignment signal can be obtained. Further, similar to the characteristics shown in the second embodiment, there is an effect of reducing the alignment error due to the GAP variation and the alignment error due to the variation of the alignment optical unit in each GAP.

Further, in this embodiment, the alignment marks 4L and 4R are marked so that the diffracted signal light is reflected by the half mirror 13L (13R) and returns to the light source, so that the stability of the light source is not deteriorated. 3L,
It is placed at a position eccentric to the 3R in the X direction,
In the range where the positional deviation is detected, the emission part of the light source and the diffracted light are separated from each other in the X direction, and the return light is not affected.

FIG. 14 is a schematic view of the essential portions of Embodiment 4 of the present invention. In the first and second embodiments described above, in the alignment optical unit 19, the separation of light projection and light reception is performed by the half mirror
In contrast to the case of L and 13R, the present embodiment is different in that a hole is made in the central portion of the sensor 12 and the light from the light source 10 passes therethrough, and the other configurations are the same.

Alignment marks 31a, 31b, 30
The diffracted light from a and 30b is condensed on the sensor 12 as shown in the figure. The positional deviation between the mask and the wafer is detected based on the distance between the two spots. By doing so, it is possible to prevent the loss of the light quantity at the half mirror, and obtain the signal light quantity that is about four times that of the second embodiment.

FIG. 15 shows a flow of manufacturing a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel, CCD or the like).

In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured.

On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by a lithography technique using the mask and the wafer prepared above.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip by using the wafer manufactured in step 4, an assembly process (dicing, bonding), a packaging process (chip encapsulation). Etc. are included.

In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 16 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist peeling), the resist that has become unnecessary due to etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device which has been difficult to manufacture in the past.

[0077]

As described above, according to the present invention, the optical properties of the alignment marks provided on the first object (mask) and the second object (wafer) are appropriately set, and the light flux to the alignment marks is changed. Even if the distance between the first object and the second object changes variously by appropriately setting the irradiation condition and the light receiving condition of the sensor that receives the light flux from the alignment mark, the relative relationship between the first object and the second object It is possible to achieve a positional deviation detection method that can detect a positional deviation with high accuracy and perform highly accurate alignment, and a semiconductor device manufacturing method using the positional deviation detection method.

In particular, according to the present invention, when detecting the mutual positional deviation between the first object and the second object, the first and second zones having power in the positional deviation detection direction are respectively applied to the first object and the second object. A plate is provided, the zone plate is irradiated with light at a projection angle θ, and the first zone plate transmits and diffracts the light.
Light that is reflected and diffracted by the first zone plate (110 light), and light that is transmitted by the first object, reflected and diffracted by the second zone plate, and transmitted and diffracted by the first zone plate (011 Both the light) and the light are detected by the sensor at the light receiving angle θ that is the same as the light projecting angle, and the positional deviation is detected based on the position information of the spot on the sensor, thereby changing the interval between the first object and the second object. There is an effect that the positional deviation detection error due to is reduced and the positional deviation can be detected without specifying the interval between the first object and the second object.

In addition, according to the present invention, when the mutual positional deviation between the first object and the second object is detected, the first object and the second object each have power in the positional deviation detection direction. A zone plate is provided, and further, third and fourth zone plates having power in the displacement detection direction are provided adjacent to the first and second zone plates, respectively, and the first and second zone plates are interposed. The amount of deviation between the first object and the second object is obtained based on position information of the first light and the second light that has passed through the third and fourth zone plates on a predetermined surface, By setting the first and third focal lengths so that the first light and the second light change with the same sensitivity with respect to the change in the distance between the first object and the second object, It reduces the error of position shift detection due to the variation of the distance between two objects,
It is possible to reduce the positional deviation detection error caused by the relative positional deviation between the zone plate, which is the positional deviation detection mark, and the projection beam, and further it is possible to reduce the positional deviation detection error caused by the variation in the shape of the zone plate.

Further, by combining these inventions, there is an effect that the positional deviation can be detected with higher accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment when the present invention is applied to an alignment system of a semiconductor exposure apparatus.

FIG. 2 is an explanatory view of a state of diffraction at an alignment mark in FIG.

FIG. 3 is an explanatory view of a light projecting lens and a light receiving lens of the alignment optical unit in FIG.

FIG. 4 is an explanatory diagram of signal waveforms obtained in the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a path of diffracted light from an alignment mark of a conventional example.

6 is an explanatory diagram showing a phase difference of diffracted light in the conventional example of FIG.

FIG. 7 is an explanatory diagram showing how the alignment mark diffracts in the second embodiment of the present invention.

FIG. 8 is an explanatory view showing an arrangement of alignment marks and an optical path of diffracted light that represents Embodiment 2 of the present invention.

FIG. 9 is an explanatory diagram showing the relationship between the magnification of the zone plate and the amount of change in the misregistration detection signal, which represents the second embodiment of the present invention.

FIG. 10 is a GAP of a mask and a wafer according to the second embodiment of the present invention.
Explanatory diagram showing how the position shift detection signal changes due to fluctuations

FIG. 11 is an explanatory diagram showing how the misregistration detection signal changes due to a change in the alignment optical unit according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram of a state of diffraction at an alignment mark that represents Embodiment 3 of the present invention.

FIG. 13 is an explanatory diagram of signal waveforms according to the third embodiment of the present invention.

FIG. 14 is an explanatory diagram showing an alignment optical unit according to a fourth embodiment of the present invention.

FIG. 15 is a flowchart of a method for manufacturing a semiconductor device of the present invention.

FIG. 16 is a flowchart of a method for manufacturing a semiconductor device of the present invention.

[Explanation of symbols]

1 mask 2 wafers 3 (3L, 3R) alignment mark 4 (4L, 4R) alignment mark 5 Wafer chuck 6 Wafer stage 7 (7L, 7R) XY stage 10 (10L, 10R) light source 11 (11L, 11R) Projection lens 12 (12L, 12R) 75 sensor 13 (13L, 13R) Half mirror 14 (14L, 14R) light receiving lens 15 (15L, 15R) mirror 16 CPU 17 Stage drive driver 19 (19L, 19R) Alignment optical unit 30a Transmission type zone plate (convex lens function) 31a Transmission type zone plate (concave lens function) 30b Reflective zone plate (concave lens function) 31b Reflective zone plate (convex lens action) 30s uneven beam spot 31s uneven beam spot

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-211629 (JP, A) JP-A-7-130636 (JP, A) JP-A-7-86122 (JP, A) JP-A-7- 86121 (JP, A) JP-A-5-243118 (JP, A) JP-A-5-234852 (JP, A) JP-A-5-217849 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1/08 G03F 7/20

Claims (10)

(57) [Claims] 1. When a first object and a second object are opposed to each other to detect a relative positional deviation between the first object and the second object, a first zone plate having power in the positional deviation detection direction is used as the first object. A second zone plate is provided on each of the second objects on the object plane, and when a light beam is emitted from the light projecting means onto the first object plane at a projection angle θ, the light is transmitted and diffracted by the first zone plate, 011 light reflected and diffracted by the second zone plate, transmitted by the first object and transmitted by the first object, reflected and diffracted by the second zone plate, and transmitted and diffracted by the first zone plate 011 Both of the lights are detected by a sensor at a light receiving angle θ that is the same as the projection angle θ, and relative positional deviation between the two is detected by using position information of the spot on the sensor. Position shift detection method. 2. The positional deviation detecting method according to claim 1, wherein each element is set such that the projection angle θ is within a range of 5 degrees to 85 degrees. 3. The misalignment detection method according to claim 1, wherein each element is set so that an incident angle of the 110 light on the second zone plate is 0 ° ± 20 °. 4. A first object and a second object are arranged to face each other.
Then, the first and third zone plates are provided on the first object plane, and the second and fourth zone plates are provided on the second object plane, respectively.
The position information of the first light flux of the light flux from the light projecting device that passes through the first and second zone plates and then enters the predetermined surface, and the light flux that enters the predetermined surface after passing through the third and fourth zone plates. Using the position information of the second light flux, the first object and the
When detecting relative positional deviation of the second object, said first object
The first light flux and the second light flux with respect to the change in the distance between the second light flux and the second light flux.
So that the incident position on the given surface of the changes with the same sensitivity
In addition, the first, fourth zone plate has positive, second, third
The positional deviation detection method is characterized in that the zone plate has a negative refractive power . 5. The first and fourth zone plates have a positive power, and the second and third zone plates have a negative refracting power. Displacement detection method. 6. The relative positional deviation between the first light flux and the second light flux is detected using the distance between the incident positions of the first light flux and the second light flux on the predetermined surface. Displacement detection method. 7. A first object and a second object are arranged to face each other.
Then, the first and third zone plates are provided on the first object plane, and the second and fourth zone plates are provided on the second object plane, respectively.
When the light beam is emitted from the light projecting means to the first object surface at the light projecting angle θ, the positional information of the first light beam which is incident on the predetermined surface after passing through the first and second zone plates and the third light beam. , The position information of the second light flux incident on the predetermined surface after passing through the fourth zone plate is detected by the sensor at the light receiving angle θ which is the same angle as the light projecting angle θ, and the position information from the sensor is used. The above
Detect relative displacement between one object and the second object
At this time, when the distance between the first object and the second object changes, the first object
The first and fourth zone plates are provided so that the incident positions of the light flux and the second light flux on a predetermined surface change with the same sensitivity.
A positional deviation detecting method characterized in that negative refractive powers are set in the positive, second and third zone plates . 8. A first object and a second object are arranged to face each other.
Then, the first and third zone plates are provided on the first object plane, and the second and fourth zone plates are provided on the second object plane, respectively.
Of the light flux from the light projecting means, when the first object and the second object have a predetermined distance, they are transmitted and diffracted by the first zone plate,
The 110 rays that have been reflected and diffracted by the second zone plate and transmitted through the first object are condensed on a predetermined surface, and the first object and the second object
When the distance from the object is different from the predetermined distance, the third
The respective elements are set so that the 110 rays that are diffracted by the zone plate of No. 1 and that are reflected and diffracted by the fourth zone plate and that are transmitted through the first object are condensed on a predetermined surface, Using the position information of the two light beams incident on the predetermined surface, the first
When detecting the relative displacement between the object and the second object,
The first and fourth zone plates are positive so that the incident positions on the predetermined surface of the first light flux and the second light flux change with the same sensitivity with respect to changes in the distance between the first object and the second object. ,
A positional deviation detecting method characterized in that negative refracting power is set in the second and third zone plates . 9. A mask and wafer relative to each other through a step of obtaining a relative positional deviation between a first object and a second object by using the positional deviation detecting method according to claim 1. A method for manufacturing a semiconductor device, characterized in that the pattern on the mask surface is transferred onto the wafer surface after performing a specific position detection, and then the semiconductor device is manufactured through a developing process. 10. A position detecting device, characterized in that a relative position deviation between a first object and a second object is obtained by using the position deviation detecting method according to any one of claims 1 to 8. .