JP2903842B2 - Interval 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 masks and wafers.
The present invention relates to an interval detection method for measuring the interval between two objects with high accuracy and a method for manufacturing a semiconductor device using the same, and particularly in the manufacture of semiconductor chips, measures the interval between a mask and a wafer with high accuracy, and sets a predetermined value. This is suitable for controlling.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, an interval between a mask and a wafer is measured by an interval measuring device or the like, and controlled so as to have a predetermined interval, and then a pattern on the mask surface is exposed on the wafer surface. Transcribed. As a result, highly accurate exposure transfer is performed.

FIG. 11 is a schematic view of an interval measuring device proposed in Japanese Patent Application Laid-Open No. 61-111402. And is focused on a point P _S between the mask M and the wafer W and arranged opposite, the mask M and the wafer W to the light beam by the lens L1 of the second object as the first object in the drawing.

[0004] At this time, the luminous flux is transmitted between the surface of the mask M and the wafer W.
Respectively reflected on the surface, a point P _W on the screen S surface through the lens L2, the being focused projected to P _M. The distance between the mask M and the wafer W is the focal point P of the light beam on the screen S.
_W, and measured by detecting the distance between the P _M.

[0005]

In the conventional surface distance measuring apparatus shown in FIG. 11, the distance between the mask and the wafer and the sensor S
The distance between the mask and the wafer is detected in correspondence with the distance between the upper light spots. For this reason, there has been a problem that the detection of the absolute value of the distance between the mask and the wafer is greatly affected by the assembly error of the detection system (for example, the positional relationship between the lens L2 and the sensor S).

In order to detect the absolute value of the interval between the mask and the wafer with high accuracy, it is necessary to separately calibrate the mask and the wafer in a certain interval state by using an accurate interval detecting means. There was a problem that the whole became complicated.

According to the present invention, there is provided a first object (mask) disposed opposite to the first object.
Provided is a method for detecting the absolute value of the surface distance between the second object (wafer) and the second object (wafer) with a simple configuration and with high accuracy without calibration of the absolute value, and a method for manufacturing a semiconductor device using the same. With the goal.

[0008]

(A) The distance detecting method according to the present invention determines the distance between the surface of the first object on which the first and second patterns having optical power are formed and the surface of the second object. A detection method, wherein first and second light beams are obliquely incident on the second object from directions different from each other, and the first light beam reflected on the surface of the second object is collected by the first pattern. And deflects the light toward the detection plane, condenses and deflects the second light flux reflected on the surface of the second object by the second pattern, and directs the second light flux onto the detection plane. Detecting the interval between the incident positions of the second light flux, forming third and fourth patterns having optical power on the first object adjacent to the first and second patterns, 3rd and 4th from two different directions on two objects The beam is obliquely incident, the third light beam reflected on the surface of the second object is diverged and deflected by the third pattern, and is directed to the detection plane. The fourth light beam reflected on the surface of the second object is The third pattern on the detection plane is diverged and deflected by the fourth pattern and directed toward the detection plane to detect an interval between incident positions of the third and fourth light beams on the detection plane. An interval value when the interval between the incident positions of the fourth light beam and the interval between the incident positions of the first and second light beams on the detection plane coincide with each other is a first value.
The reference for detecting the surface interval of the second object, and the first,
Using at least one of an interval between incident positions of the second light beam and an incident position of the third and fourth light beams, the first and second light beams are used.
It is characterized by detecting the surface interval of the object.

In particular, (A-1) the first and second pattern sets are formed at a plurality of different places on the first object,
The set of the third and fourth patterns is formed in at least one place on the first object, and the set of the third and fourth patterns formed in the at least one place and the set corresponding to the set The distance value serving as a reference for detecting the surface distance between the first and second objects is determined by using a set of first and second patterns, and the third and fourth light sources formed in the at least one location are determined. Surfaces of the first and second objects with respect to other portions different from the at least one location using first and second pattern sets different from the first and second pattern sets corresponding to the pattern sets Detecting an interval; (a-2) forming a set of the third and fourth patterns at a plurality of different locations on the first object;
The first and second pattern sets are formed in at least one place on the first object, and the first and second pattern sets formed in the at least one place and the sets corresponding to the sets are formed. The distance value serving as a reference for detecting the surface distance between the first and second objects is determined using a set of third and fourth patterns, and the first and second distances formed in the at least one location are determined. The surfaces of the first and second objects with respect to another portion different from the at least one position using a third and fourth pattern set different from the third and fourth pattern set corresponding to the pattern set Detecting an interval; (A-3) a set of the first and second patterns and the third and third patterns at a plurality of different locations on the first object;
A fourth set of patterns is formed, wherein the first,
Detecting a surface interval between the first and second objects with respect to a place using a set of a second pattern and a set of the third and fourth patterns; (b-4) detecting a set of the first and second patterns; The third and fourth sets of patterns are arranged in a line-symmetric relationship with respect to a certain axis.

(B) In the method of manufacturing a semiconductor device according to the present invention, a surface interval between a mask on which first and second patterns having optical power and a circuit pattern are formed and a surface of a semiconductor wafer are detected. A method for manufacturing a semiconductor device, comprising: exposing a wafer with a circuit pattern of the mask after adjusting a surface interval to a predetermined interval, wherein a first light flux and a second light flux from different directions are formed on the wafer from different directions. The first light flux that is obliquely incident and reflected on the surface of the wafer is condensed and deflected by the first pattern, is directed to a detection plane, and the second light flux reflected on the surface of the wafer is reflected.
The light flux is condensed and deflected by the second pattern and directed to the detection plane, and the first and second light beams on the detection plane are focused on the detection plane.
In detecting an interval between incident positions of a light beam, third and fourth patterns having optical power are formed on the mask adjacent to the first and second patterns, and directions different from each other are formed on the wafer. From the third and fourth light beams obliquely incident thereon, and the third light beam reflected on the surface of the wafer is diverged and deflected by the third pattern, directed toward a detection plane, and reflected on the surface of the wafer. Four light beams are diverged and deflected by the fourth pattern and directed toward the detection plane, and the distance between the incident positions of the third and fourth light beams on the detection plane is detected. The distance between the incident positions of the third and fourth light beams and the distance between the incident positions of the first and second light beams on the detection plane coincide with each other to detect the distance between the mask and the surface of the wafer. Of the standard, Serial first, the interval between the incident position of the second light flux and the third mask by using at least one of the distance between the incident position of the fourth light beam, detecting the spacing of the wafer,
It is characterized in that the surface distance between the mask and the wafer is adjusted.

Particularly, the present invention is characterized in that the set of the first and second patterns and the set of the third and fourth patterns are arranged in a line-symmetric relationship with respect to a certain axis.

(C) An exposure apparatus for manufacturing a semiconductor device according to the present invention detects a surface interval between a mask on which first and second patterns having optical power and a circuit pattern are formed, and a surface of a semiconductor wafer, After adjusting the surface interval to a predetermined interval, in the semiconductor device manufacturing exposure apparatus that exposes the wafer with the circuit pattern of the mask, the mask is provided with optical power adjacent to the first and second patterns. Third and fourth patterns are formed, and first and second light beams are obliquely incident on the wafer from different directions, and the first light beam reflected on the surface of the wafer is reflected by the first pattern. The light is focused and deflected to be incident on a photoelectric detector, and the second light flux reflected on the surface of the wafer is focused and deflected by the second pattern. A third light beam is obliquely incident on the wafer from directions different from each other, and the third light beam reflected on the surface of the wafer is diverged and deflected by the third pattern. A detection optical system that irradiates the fourth light flux reflected on the surface of the wafer while being incident on the photoelectric detector and diverges and deflects the fourth light flux according to the fourth pattern and makes the fourth light flux incident on the photoelectric detector; A signal from the photoelectric detector for detecting an interval between incident positions of the first and second light beams on the light receiving surface and an interval between incident positions of the third and fourth light beams on the second light receiving surface. And a processing unit that sets an interval value when the interval between the incident positions of the third and fourth light beams and the interval between the incident positions of the first and second light beams coincide with each other. For detecting the distance between mask and wafer It is characterized in that it comprises a memory for storing as a quasi.

[0013]

FIG. 1 is a schematic view of a main part of an optical system of a part of a first embodiment in which the present invention is applied to an apparatus for measuring the distance between a mask and a wafer in a semiconductor manufacturing apparatus. FIG. FIG. 3 is a perspective view of a main part around an optical element.

In FIG. 1, reference numeral 71 denotes an LED or H
luminous flux from e-Ne laser, semiconductor laser, etc., 72
Is a first object, for example, a mask. A second object 73 is, for example, a wafer, and includes a mask 72 and a wafer 73.
Are arranged to face each other with an interval d _O as shown in FIG.

[0015] 73 ₁ the distance between the mask 72 and the wafer 73 indicates the position of the wafer 73 when the d _O, 73 ₂ is the position of the wafer 73 when the interval between the mask 72 and the wafer 73 is d _O + d _G Is shown.

Reference numerals 78 and 83 denote first and second physical optical elements respectively provided on a part of the surface of the mask 72.
Shows the arrangement. These physical optical elements 78,
Reference numeral 83 includes, for example, a diffraction grating, a zone plate, a grating lens, and the like. Reference numeral 76 denotes a condenser lens (also simply referred to as a “lens”), and its focal length is f _S.

Numeral 77 denotes a light receiving means (also referred to as a "sensor"). As will be described later, two line sensors (77) as a first detecting means and a second detecting means shown in FIG.
It consists of _one, 77 ₂₎ and PSD or the like, and detects the center of gravity position in the sensor plane of the incident light beam.

Here, the center of gravity of the light beam is defined as a vector of zero when the value obtained by multiplying the position vector of each point in the cross section by the light intensity at that point in the light beam cross section is integrated over the entire cross section. As another example, the position of the point where the light intensity reaches a peak may be detected.

Reference numeral 79 denotes an optical axis. Although FIG. 1 shows one measurement system, actually, as shown in FIG. 2, two measurement systems having gratings 78 and 83 of the same configuration are provided in a symmetrically folded relation with respect to the optical axis 79. I have. FIG.
For convenience, one measurement system below the optical axis 79 is shown.

[0020] 9 is a signal processing circuit determines the position of the center of gravity of the light beam incident on the light receiving means 77 ₁ on the surfaces of using two line signals from the sensor 77 _1, 77 ₂ of the light-receiving unit 77, as described below seeking calculates the distance d _o between the mask 72 and the wafer 73.

Reference numeral 10 denotes an optical pickup, which includes a condenser lens 76, a light receiving means 77, and a signal processing circuit 9 if necessary, and is relatively movable with respect to the mask 72 and the wafer 73. .

In this embodiment, the light beam 71 (wavelength λ = 830) of monochromatic light or quasi-monochromatic light from the semiconductor laser LD is used.
nm) is perpendicularly incident on a point A on a first Fresnel zone plate (hereinafter abbreviated as FZP) 78 on the mask 72 surface. A predetermined order diffracted light diffracted at an angle θ ₁ from the first FZP 78 is converted into a point B on the wafer 73 surface.
The light is reflected at (C).

[0023] Among the reflected light 74 ₁ is reflected light, the reflected light 74 ₂ when the wafer 73 is located at the position 73 ₁ close to the mask 72 wafer 73 is displaced from the position 73 ₁ by a distance d _G Position 73 It is the reflected light when it is at ₂ . Then a point D on the second FZP83 surface of the light reflected on the first object 72 side of the wafer 73 (when position 73 ₂ E) are caused to enter the.

The second FZP 83 has an optical function of changing the exit angle of the output diffracted light according to the incident position of the incident light beam.

A predetermined order diffracted light 74 ₁ diffracted at an angle θ ₂ from the second FZP 83 (74 at the position 73 ₂ ).
₂ ) is guided to the surface of the light receiving means 77 via the condenser lens 76. The condenser lens 76 does not have to have the position 75 and the sensor 77 at the same magnification, but it is assumed that an image is formed in a conjugate relation of the same magnification for convenience of the description below.

At this time, the incident light beam 74 ₁ (position 73) on the surface of the line sensor 77 ₁ of the light receiving means 77
_In the case of ₂ , the distance between the mask 72 and the wafer 73 is calculated using the center of gravity of 74 ₂ ).

In the present embodiment, the first and second FZPs 78 and 83 provided on the surface of the mask 72 are formed at a preset known pitch, and a predetermined order (for example, ± 1 order) of the luminous flux incident thereon. diffraction angle theta ₂ at a predetermined incident position of the diffraction angle theta ₁ and FZP83 in FZP78 the diffracted light) is obtained in advance.

In this embodiment, two measuring systems are provided so as to be symmetrically folded with respect to the optical axis 79. Therefore, the mask when the wafer 73 is at the position 73 ₁ 72
The distance between the light spot 80 ₁ and the wafer 73 is symmetrical with respect to the optical axis 79 at a position y ₁ away from the optical axis 79 on the sensor surface 77 (for example, on the line sensor 77 ₁ surface in FIG. 9). 80 ₁ ′ (line sensor 77 in FIG. 9)
Light spots 100-α and 100-β) are generated on _one surface. Mask spot interval between the symmetric light spot 80 ₁ 'with respect to the sensor surface 77 the light spot 80 ₁ and the optical axis 79 made on (in FIG. 9 interval 91) is 72 and the wafer 73
Is given.

FIG. 3 is an explanatory diagram for explaining the measuring principle of the distance measuring device according to the present invention. FIG. 7 shows the surface 7 in FIG.
The portion on the left side from 5 is enlarged.

Next, the measurement principle of the present invention will be described with reference to FIG. In FIG. 3, since the surface 75 and the sensor 77 are in the same conjugate relationship with respect to the lens 76, how far the light spot reaches from the optical axis 79 on the sensor 77 is as if the sensor 75 May be regarded as if there is. However, lens 7
6, the upper and lower positions in the figure are reversed with respect to the optical axis.

[0031] When the wafer 73 in FIG. 3 is in the position 73 _1, and reflected (specular reflection) by the diffraction light wafer 73 caused by the diffraction grating 78 on the mask 72, the diffraction grating 8
The position 83 ₁ (D) is reached. Wafer 7 at position 73 ₂
When there are 3, light diffracted by the diffraction grating 78 reaches the position 83 ₂ of the diffraction grating 83 receives the regular reflection at the wafer 73.

It is assumed that the positions 83 ₁ and 83 ₂ are separated from the optical axis 79 by distances x ₁ and x ₂ (μm), the diffraction grating 83 has a diffractive action converging on the point F, and the optical axis Using the position as the origin and a coordinate system of (p, q), F
If (a, k) and the unit μm point 84 are located on the optical axis 79 of the surface 75, the point 84 is a point 84 (b, o).

[0033] In this case, the light beam 74 ₁ and the beam 74 ₂ surface 75
When the distances from the optical axis at the time of reaching are respectively y ₁ and y ₂ (however, y ₁ , y ₂ > 0) When k> x ₂ > x ₁ ,

[0034]

(Equation 1) Since | x ₁ | and | x ₂ | correspond to the gap (interval) between the mask 72 and the wafer 73, the relationship of the equations is that the gaps g ₁ and g ₂ (the position of the wafer 73 at 73 ₁ and 73 ₂ , respectively) (Corresponding to the distance from the mask 72) and the sensor 77
It can be seen that there is a linear relationship between the upper light spot intervals (corresponding to 2y ₁ and 2y ₂ respectively). FIG. 4 shows the situation by a solid line.

That is, the diffraction grating (grating) 83 may be set as a diffraction grating that generates diffracted light that acts as a convex lens that converges to the point F. (Corresponding to the patterns 92-α (first pattern) and 92-β (second pattern) in FIG. 8 described later).

In FIG. 3, the point 85 ₁ on the surface 75
Conclude the point 83 _2, when the intersection point formed by connecting a point 85 ₂ and the point 83 ₁ and point F', the coordinates of the point F'(p _f, q _f) is

[0037]

(Equation 2) Indicated by

That is, if the grating 83 is set as a diffraction grating for generating a diffracted light that acts as a concave lens having a focal point at the point F '(patterns 94-α (third pattern) in FIG. 8 and 94-β (fourth pattern)). The relationship between the gap d and the light spot interval on the sensor surface 77 is shown in FIG.
, The characteristics are as shown by the dashed line. That is, when the grating 83 has a convex lens function with the point F as the focal point, the solid line in FIG. 4 is obtained.

As described above, according to the present invention, the grating 83
And a pattern having a convex lens action and a concave lens action (see FIG. 8). That is, it is composed of a first pattern 92-α and a second pattern 92-β having a convex lens function and a third pattern 94-α and a fourth pattern 94-β having a concave lens function.

That is, in this embodiment, the first and second light beams are obliquely incident on the second object 73 from different directions.
The first light beam reflected by the surface of the second object
The second light reflected on the surface of the second object by being condensed and deflected by the pattern 92-α and directed onto the detection plane 77,
The light flux is condensed and deflected by the second pattern 92-β and directed onto the detection plane 77, and the interval between the incident positions of the first and second light fluxes on the detection plane 77 is detected. The third and fourth objects are placed on the object 73 from different directions.
Is obliquely incident, the third light beam reflected on the surface of the second object is diverged and deflected by the third pattern 94-α, is directed to the detection plane 77, and is reflected on the surface of the second object. The fourth light beam is transmitted to the fourth pattern 94-β.
To diverge and deflect toward the detection plane 77 so as to detect the interval between the incident positions of the third and fourth light beams on the detection plane, and the third and fourth light beams on the detection plane The distance between the first object 72 and the second object 73 is detected when the distance between the incident positions of the first object and the second object 73 coincides with the distance between the incident positions of the first and second light beams on the detection plane. The surface of the first object 72 and the second object 73 is determined by using at least one of the interval between the incident positions of the first and second light beams and the interval between the incident positions of the third and fourth light beams. The interval has been detected.

FIG. 3 shows a specific example. a = 1000 μm, b = 18700 μm, | x ₁ | = 5
μm, | x ₂ | = 29 μm, | k | = 100 μm,

[0042]

(Equation 3) Since the intervals 2y ₁ and 2y ₂ are the light spot intervals on the sensor surface 77 (the interval 91 in FIG. 9), characteristics as shown by the solid line in FIG. 5 are obtained. Also, at this time,

[0043]

(Equation 4) And the point F ′ (−11119.760, 75.940)
When a concave lens function having a focal point of is given to the grating 83, the characteristic shown by the one-dot chain line in FIG. 5 is obtained.

At this time, the intersection of the solid line characteristic and the one-dot chain line characteristic corresponds to an interval (gap) of 70 μm. Next, this will be shown by check.

In FIG. 3, the midpoint between x ₁ and x ₂ and the point F ′
Connecting a line to seek to Q ₁ coordinate point intersects the surface 75.
This point Q ₁ is the (-1119.76,75.940) (0, -17) because a straight line and the intersection of P = 18700 connecting, coordinate the intersection Q ₁ is (18700, -156
9.1).

On the other hand, the coordinates of the point Q ₂ at which the straight line connecting the midpoint between x ₁ and x ₂ and the point F intersects the surface 75 are obtained. That is,
(1000, -100) and (0, -17) therefore is the intersection of the straight line and p = 18700 connecting, the coordinate intersection point Q ₂ is a (18700, -1569.1).

The positions of the points Q ₁ and Q ₂ coincide, and the spot interval on the sensor 77 at this time is 1569.1 × 2 = 3.
138.2 μm, and the gap is 70 μm in FIG.
It can be seen that the value at the time of (1) is the intersection Q of the characteristics of the solid line and the one-dot chain line.

Accordingly, as shown in FIG. 3, a part of the grating 83 on the mask 72 is formed into a pattern (first pattern 92-α, second pattern 92-β) having a convex lens function with the point F as a focal point. In the vicinity of this pattern, a pattern corresponding to the grating 78 and a grating pattern (third pattern 94-3) having a concave lens function with a part of the grating 83 as a focal point at the point F ′.
α, the fourth pattern 94-β).

Four spots generated by these gratings (see FIG. 9), ie, two pairs of intervals (91, 9)
2) is set so that the intersection Q of the characteristics shown in FIG. 5 obtained by using the two-line sensor (77 ₁ , 77 ₂ ) as the sensor 77 in FIG. 1 is a gap of 70 μm. The intersection of the characteristic with the light spot interval on the sensor can specify that the gap has an absolute value of 70 μm.

Further, in this method, for example, the distance between the lens 76 and the mask 72, the distance between the lens 76 and the sensor 7
Even if the interval of 7 slightly changes, the value of the intersection Q in FIG. 5 is hardly affected, and the interval can be determined as 70 μm with high accuracy by using the intersection of the characteristics in FIG. Next, this will be described with reference to the drawings.

When the distance between the mask 72 and the lens 76 or the distance between the lens 76 and the sensor 77 changes, the surface 75 shown in FIG. That is, the position conjugate with the sensor 77 with respect to the lens 76 is shifted to, for example, the surface 89. At this time, the light spot interval of the diffracted light passing through the mask 72 and the wafer 73 on the surface 89 is obtained.

If it is shifted from the surface 75 by a distance Δb,
The intersection S ₁ between the line connecting the point 83 ₁ and the point F and the surface 89 is S ₁ (18700 + Δb, −1781.5−0.095)
· [Delta] b) In addition, the intersection S ₂ of the straight line and the surface 89 connecting the point 83 ₂ and the point F is S ₂ (18700 + Δb, -1356.7-0.071
· [Delta] b) Similarly intersection S of the straight line and the surface 89 connecting the point F'and the point 83 _1
1 ′ is S ₁ ′ (18700 + Δb, −1356.7−0.07)
23 · Δb) The intersection S ₂ ′ between the straight line connecting the point F ′ and 83 ₂ and the surface 89 is S ₂ ′ (18700 + Δb, −1781.5−0.09)
37 · Δb).

FIG. 6 shows the gap between the mask 72 and the wafer 73 and the light spot interval characteristics on the sensor surface 77 obtained from these values.

In FIG. 6, the straight lines L _A and L _B are the characteristics as designed, that is, the characteristics when the surface of the lens 76 conjugate with the sensor 77 is on the surface 75. Straight lines L _A ′, L _B ′
Is a surface 89 conjugated to the sensor 77 with respect to the lens 76.
This is the characteristic that is obtained when there is a deviation.

In FIG. 6, an intersection Q between the characteristics of the line L _A and the line L _B and an intersection between the characteristics of the line L _A 'and the line L _B ' are Q '. When the point Q is expressed in the coordinate system of (gap, light spot interval on the sensor) in FIG. 6 as described above, the coordinate of the point Q is Q (70,3138.2). Next, the value of the coordinates of the point Q 'is obtained.

The straight line L _A ′ is a point (50, 2713.4+
0.145 · Δb) and point (90,3563 + 0.187)
Δb).

The line L _B ′ is a point (50,3563 + 0.1
9 · Δb) and point (90,2713.4 + 0.142 · Δ)
It is a straight line connecting b). Therefore, the coordinates of the point Q ₁ ′

[0058]

(Equation 5) Is the intersection. This value is 70 μm regardless of the distance Δb
The point Q or the point Q ', that is, the value at the intersection can be determined to be the gap 70 μm.

FIG. 7 is a schematic view of a main part of an embodiment when the surface gap measuring apparatus of the present invention is applied to an exposure apparatus for manufacturing a semiconductor device. In the figure, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.

In FIG. 7, reference numeral 101 denotes a light source, which comprises, for example, a laser diode, an LED, a mercury lamp and the like.

Waves of electromagnetic waves, sound waves and the like (hereinafter referred to as “light beams”) emitted from the light source 101 are converted into parallel light beams by a collimator lens, condensed by a projection lens 103, reflected by a mirror 104, and reflected by a protection window 105. For example, the first object 1 irradiates the grating lenses 78 and 83, which are a kind of Fresnel zone plate in the scribe line 100 region of the mask surface 72, as oblique directions as plane waves. The grating lenses 78 and 83 are provided at four positions at four corners of the mask 72.

In this embodiment, the grating lens 78,
The luminous flux incident on the beam 83 does not necessarily have to be a plane wave, but for the sake of convenience, an example in which the light beam is entered as a plane wave will be described. A plane wave is incident on the grating lenses 78 and 83, the incident light is diffracted, and spot light generated by reflection on the wafer surface is generated on the sensor 77. The spot interval between the mask 72 and the wafer 73 is as described above.
Is given.

FIG. 8 shows a mask 72 for measuring the surface interval.
It is an example of the pattern of the grating lenses 78 and 83 above.

In FIG. 8, 91-α, 91-β (93-
α, 93-β) is the grating lens 7 in FIG.
The first pattern 92-α and the second pattern 92-β (the third pattern 94-α and the fourth pattern 94-β) correspond to the pattern of the grating lens 83 in FIG. Light that has entered the area of the pattern 91-alpha is reflected by the wafer 83 after being diffracted, and again diffracted by the first pattern 92-alpha, leading to the sensor ₇₇₁ as the first detecting means through the lenses 76.

That is, the pattern 91-α and the first pattern 9
2-α generates one light spot 101-α on the sensor 771 in _one set. Pattern 91-alpha and the light spot first pattern 92-alpha is made is a light spot 100-alpha sensors 77 on _one of the shown in FIG. 9, the light spot to make the pattern 91-beta and the second pattern 92-beta The light spot 100 on the sensor 77 ₁ shown in FIG.
−β. First pattern 92-α and second pattern 92
−β is symmetric about the optical axis 79.

The first pattern 92-α and the second pattern 92-β act as convex lenses to converge the diffracted light to the point F in FIG. Similarly, the third pattern 94-α and the fourth pattern 94-β act as a concave lens, and provide the diffracted light with a concave lens as a focal point at the point F ′ in FIG.

[0067] Thus, the light spot on the pattern 93-alpha and the line sensor 77 ₂ of the third pattern 94-alpha is made light spot as the second detection means in FIG 1
01-α, the pattern 93-β and the fourth pattern 94
The light spot created by −β is the light spot 10 in FIG.
1-β.

[0068] Thus, the characteristics of the spot interval of the light spot 100-alpha and the light spot 100-beta give in response to the gap between the mask and wafer are linear L _B in FIG. 6, the light spot 101-alpha and the light spot 101 spot interval of -β is property of yielding in accordance with the gap between the mask and the wafer is linear L _a in FIG.

The example of the pattern in FIG. 8 is an embodiment in the case where a = 1 mm, b = 19 mm, and k = 100 μm in FIG.

In this embodiment, the set of the first and second patterns is formed at a plurality of different places on the first object, and the third set is formed at least one place on the first object. , A fourth pattern set is formed, and the first and second pattern sets corresponding to the third and fourth pattern sets formed at the at least one location are used to form the first pattern set. , The distance value serving as a reference for detecting the surface distance of the second object is determined, and the first and second patterns corresponding to the set of the third and fourth patterns formed at the at least one location are determined. The distance between the surfaces of the first and second objects with respect to another portion different from the at least one position may be detected using a first and second pattern set different from the set.

Further, the third and fourth pattern sets are formed at a plurality of different places on the first object, and the first and second patterns are formed at least at one place on the first object. A set is formed, the first formed in the at least one location,
The distance value serving as a reference for detecting a surface distance between the first and second objects is determined by using a set of a second pattern and a set of the third and fourth patterns corresponding to the set. Different from the at least one location by using a third and fourth pattern set different from the third and fourth pattern sets corresponding to the first and second pattern sets formed at one location You may make it detect the surface interval of the said 1st, 2nd object regarding another location.

The set of the first and second patterns and the set of the third and fourth patterns are formed at a plurality of different places on the first object, and the sets of the first and second patterns at each place are formed. The distance between the surfaces of the first and second objects with respect to a location may be detected using a set of the set and the third and fourth patterns.

Also, a set of the first and second patterns and third and fourth patterns
The pair with the pattern is arranged so as to be line-symmetric with respect to a predetermined axis.

An example of the pattern setting on the mask 72 is as follows.
Various other settings can be made, and the pattern corresponding to the area in FIG. 8 can be arranged as shown in FIG.

In FIG. 10, patterns 91-α and 92-
α, 91-β, 92-β, 93-α, 93-β, 94-
The details of the pattern in each area of α, 94-β are almost the same as those in FIG. The situation of light incidence and diffraction, reflection and re-diffraction on the pattern is likewise conceivable.

In the present embodiment, the semiconductor chip is manufactured by transferring the circuit pattern on the mask surface onto the wafer surface through the process of obtaining the surface distance between the mask and the wafer as described above, and performing the known development process. doing.

As described above, according to the present invention, a pattern is set such that the detection signal characteristics of the surface interval (gap) between the mask and the wafer and the signal obtained by the sensor intersect in the middle as shown in FIG. Then, the absolute value of the gap is accurately determined using the intersection point.

In the above embodiment, an example of the X-ray exposure apparatus using the proximity method has been described. However, the present invention relates to a so-called optical stepper, in which a reticle image is formed on a wafer through a projection (imaging) lens. The same can be applied to the detection of the interval between the focus positions of the exposure apparatus for projecting and printing on the top.

[0079]

According to the present invention, the absolute value of the surface distance between the first object (mask) and the second object (wafer) which are arranged opposite to each other as described above can be obtained without any calibration of the absolute value by a simple configuration. It is possible to achieve a surface interval measuring device capable of detecting with high accuracy and a method of manufacturing a semiconductor chip using the same.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a part of an optical system according to a first embodiment of a distance measuring apparatus of the present invention.

FIG. 2 is an explanatory diagram of a physical optical element in FIG. 1;

FIG. 3 is an explanatory diagram of a measurement principle of the interval measuring device according to the present invention.

FIG. 4 is an explanatory diagram showing a relationship between a surface interval and a light spot interval on a sensor.

FIG. 5 is an explanatory diagram showing a relationship between a surface interval and a light spot interval on a sensor.

FIG. 6 is an explanatory diagram showing a relationship between a surface interval and a light spot interval on a sensor.

FIG. 7 is a schematic diagram when the distance measuring apparatus of the present invention is applied to an exposure apparatus for manufacturing a semiconductor element.

FIG. 8 is an explanatory view of a physical optical element on the mask surface of FIG. 7;

9 is an explanatory diagram of a light spot on the sensor surface of FIG. 7;

FIG. 10 is an explanatory diagram of another embodiment of the physical optical element on the mask surface.

FIG. 11 is a schematic view of a main part of a conventional distance measuring device.

[Explanation of symbols]

72 Mask 73 Wafer 76 Condensing lens 77 Light receiving means 77 ₁ First detecting means 77 ₂ Second detecting means 9 Signal processing circuit 10 Optical pickup 100 Scribe line 101 Light source 102 Collimator lens 104 Mirror

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-233165 (JP, A) JP-A-5-4013 (JP, A) JP-A-4-12207 (JP, A) JP-A-3-3 229104 (JP, A) JP-A-3-116816 (JP, A) JP-A-3-48706 (JP, A) JP-A-4-12523 (JP, A) JP-A-2-93305 (JP, A) JP-A-2-74802 (JP, A) JP-A-2-74803 (JP, A) JP-A-2-167409 (JP, A) JP-A-2-1503 (JP, A) JP-A-2-154102 (JP, A) JP-A-60-52025 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027

Claims (8)

(57) [Claims] 1. A method for detecting a surface interval between a surface of a first object on which first and second patterns having optical power are formed and a surface of a surface of a second object, the method comprising: The first and second light beams are obliquely incident from different directions, the first light beam reflected on the surface of the second object is condensed and deflected by the first pattern, and is directed to a detection plane. The second light beam reflected by the surface of the second light beam is condensed and deflected by the second pattern, is directed to the detection plane, and detects an interval between the incident positions of the first and second light beams on the detection plane. Forming third and fourth patterns having optical power adjacent to the first and second patterns on the first object, and forming third and fourth patterns on the second object from different directions from each other. The light beam is obliquely incident and reflected on the surface of the second object. The third light beam is diverged and deflected by the third pattern to be directed to the detection plane, and the fourth light beam reflected by the surface of the second object is diverged and deflected by the fourth pattern to be deflected and deflected by the fourth pattern. , The interval between the incident positions of the third and fourth light beams on the detection plane is detected, and the interval between the incident positions of the third and fourth light beams on the detection plane is detected on the detection plane. An interval value when the interval between the incident positions of the first and second light beams coincides with each other as a reference for detecting the surface interval between the first and second objects, and the incident position of the first and second light beams. An interval detection method, wherein the interval between the surfaces of the first and second objects is detected using at least one of an interval between the first and second objects and an interval between incident positions of the third and fourth light beams. 2. The first and second pattern sets are formed at a plurality of different locations on the first object, and the third and fourth patterns are formed on at least one location on the first object. A set is formed, and a surface of the first and second objects is formed by using a set of third and fourth patterns formed at the at least one location and a set of the first and second patterns corresponding to the set. The interval value serving as a reference for detecting an interval is determined, and a first value different from the first and second pattern sets corresponding to the third and fourth pattern sets formed in the at least one location is determined. 2. The distance detecting method according to claim 1, further comprising detecting a surface distance between the first and second objects with respect to another location different from the at least one location, using a set of second and third patterns. 3. A set of the third and fourth patterns is formed at a plurality of different locations on the first object, and the first and second patterns are formed at least at one location on the first object. A set is formed, and a surface of the first and second objects is formed by using a set of the first and second patterns formed at the at least one location and a set of the third and fourth patterns corresponding to the set. A third value different from the third and fourth pattern sets corresponding to the first and second pattern sets formed in the at least one location is determined by determining the interval value serving as a reference for detecting the interval. 2. The distance detecting method according to claim 1, further comprising detecting a surface distance between the first and second objects at another location different from the at least one location using a set of the fourth and fourth patterns. 4. A set of the first and second patterns and a set of the third and fourth patterns are formed at a plurality of different places on the first object, and the first and second patterns at each place are formed. The distance detecting method according to claim 1, wherein the distance between the first and second objects with respect to the location is detected using a set of patterns and the set of the third and fourth patterns. 5. The apparatus according to claim 1, wherein said first and second pattern sets and said third and fourth pattern sets are arranged in a line-symmetric relationship with respect to a certain axis. Or the interval detection method of 4. 6. After detecting a surface interval between a mask on which first and second patterns having optical power and a circuit pattern are formed and a surface of a semiconductor wafer, and adjusting the surface interval to a predetermined interval, A method of manufacturing a semiconductor device, comprising: exposing the wafer with a circuit pattern of the mask, the method comprising:
Is obliquely incident, the first light beam reflected on the surface of the wafer is condensed and deflected by the first pattern, is directed to a detection plane, and the second light beam reflected on the surface of the wafer is focused on the second surface. In the one that focuses and deflects the light by two patterns and directs the light toward the detection plane and detects the interval between the incident positions of the first and second light beams on the detection plane, the first and second patterns are provided on the mask. Forming third and fourth patterns having optical power adjacent to
Third and fourth light fluxes are obliquely incident on the wafer from different directions, and the third light flux reflected on the surface of the wafer is diverged and deflected by the third pattern and directed toward a detection plane. The fourth light flux reflected by the surface of the third light beam is diverged and deflected by the fourth pattern and directed toward the detection plane, and the third light beam on the detection plane is
The interval between the incident positions of the fourth light beam is detected, and the interval between the incident positions of the third and fourth light beams on the detection plane and the incident position of the first and second light beams on the detection plane are detected. Is used as a reference for detecting the surface distance between the mask and the wafer, the distance between the incident positions of the first and second light beams and the distance between the incident positions of the third and fourth light beams. A method for detecting a surface distance between a mask and a wafer by using at least one of the above distances and adjusting the surface distance between the mask and the wafer. 7. The manufacturing of a semiconductor device according to claim 6, wherein the first and second pattern sets and the third and fourth pattern sets are arranged in a line-symmetric relationship with respect to a certain axis. Method. 8. A mask on which first and second patterns having optical power and a circuit pattern are formed, and a surface interval of a surface of the semiconductor wafer are detected, and after adjusting the surface interval to a predetermined interval, In a semiconductor device manufacturing exposure apparatus for exposing the wafer with a circuit pattern of the mask, third and fourth patterns having optical power are formed on the mask adjacent to the first and second patterns. , A first and a second from different directions on the wafer.
Obliquely incident, and the first light beam reflected on the surface of the wafer is condensed and deflected by the first pattern to be incident on a photoelectric detector, and the second light beam reflected on the surface of the wafer is reflected by the first pattern. The light is condensed and deflected by the second pattern, is incident on the photoelectric detector, and the third and fourth light fluxes are obliquely incident on the wafer from different directions from each other, and the third light reflected on the surface of the wafer is reflected by the third light flux. The light beam is diverged and deflected by the third pattern and is incident on the photoelectric detector, and the fourth light beam reflected on the surface of the wafer is diverged and deflected by the fourth pattern and is incident on the photoelectric detector. A detection optical system, an interval between incident positions of the first and second light beams on the first light receiving surface of the photoelectric detector, and an incidence of the third and fourth light beams on the second light receiving surface. Means for processing a signal from the photoelectric detector in order to detect an interval between positions, wherein the processing means comprises an interval between incident positions of the third and fourth light beams and the first and second light beams. An exposure apparatus for manufacturing a semiconductor device, comprising: a memory for storing an interval value when the interval between the incident positions of the two coincides as a mask and a reference for detecting a surface interval of a wafer.