JP3193549B2 - Exposure method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and apparatus for use in semiconductor manufacturing and the like.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor elements, the accuracy of an exposure apparatus for exposing a semiconductor has been improved, and in particular, a space between a substrate such as a wafer to be exposed (hereinafter, referred to as a "substrate") and a mask. The precision of the alignment and the perpendicularity of the mask to the optical axis of the exposure light greatly affect the precision of the transfer printing of the mask pattern, and various measures have been made to improve these.

In general, an alignment optical system for aligning a substrate and a mask is set in advance so that alignment light is incident on the mask at a predetermined angle, and the alignment optical system is used to adjust the position between the substrate and the mask. Before the alignment, it is necessary to adjust the attitude of the entire exposure chamber so that the mask is perpendicular to the optical axis of the exposure light.

FIG. 9 shows a charged particle storage ring radiation (hereinafter, referred to as “charged particle storage ring”).
It is called "SR-X-ray". 1) shows a general example of an exposure apparatus that uses exposure light as an exposure light. The exposure apparatus 101 includes an exposure chamber 101 supported by a gantry 101a, and an exposure chamber 101 provided with an SR drawn from a light emitting point of a charged particle storage ring (not shown). a beam duct 101b for introducing -X lines L _0, and the beryllium window 101d provided in the opening 101c of the exposure chamber 101 which opens the contrary, supported by the support frame 102 is an inner wall integral with the exposure chamber 101 Alignment optical system 103 and mask holder 104, and known positioning stage 105 for positioning substrate W ₀ in exposure chamber 101.
Adjusting device 1 for adjusting the attitude of exposure chamber 101
Reference numeral 06 denotes a rotating device 106a for rotating the entire exposure chamber 101 on the gantry 101a around one axis (hereinafter, referred to as a "y-axis") perpendicular to the gantry 101a, and the gantry 101a.
And a plurality of legs 106b provided between the floor and the floor.
1 along with the entire height, one axis perpendicular to the y-axis (hereinafter “x
Axis. ) Can be adjusted. Further, the positioning stage 105 is a suction chuck 1 that suctions and holds the substrate W ₀ held thereon.
There is an X-ray intensity sensor 107 that detects the intensity of the SR-X-ray L ₀ near the side of 05a.

[0005] Before starting the exposure of the substrate W ₀ by SR-X-ray L ₀ is to detect the positional deviation between the mask M _0, which is held by the substrate W ₀ and the mask holder 104 by the alignment optical system 103 Before the alignment of the mask with the substrate W ₀ , the posture (ωx, ωy) of the exposure chamber 101 is changed so that the surface of the mask M ₀ is perpendicular to the optical axis of the SR-X-ray L _0. Need to adjust.

Conventionally, this operation is fitted with a pin-hole member having a pair of pin holes in place of the mask M ₀ in the mask holder 104, the exposure chamber 101 by the attitude adjustment device 106 while applying SR-X-ray L ₀ SR-X-ray L ₀ the orientation by changing the passing through both pinholes finds the posture entering the X-ray intensity sensor 107, was done by fixing the exposure chamber 101 to the position (JP-2
-72611 and JP-A-4-350923. If the optical axis of the exposure light SR-X-ray L ₀ is not perpendicular to the mask M ₀ , a transfer displacement proportional to the inclination angle of the normal to the mask surface with respect to the optical axis occurs.
That is, as shown in FIG. 10, the substrate W ₀ generally has a resist film R on the wafer pattern WP formed by the above-described process, and the mask pattern MP of the mask M ₀ is transferred over the wafer pattern WP. You. When the optical axis O ₀ of the SR-X-ray L ₀ , which is the exposure light, is shifted by Δωy around the y-axis with respect to the normal direction of the mask M ₀ , the mask pattern MP moves in the x-axis direction on the wafer pattern WP. Is transferred by Δxo, and the transfer deviation Δxo is obtained as follows.

[0007] Δxo = G · Δωy where G: substrate W ₀ and the proximity gap (distance) of the mask M ₀ Similarly, the optical axis O ₀ of SR-X-ray L ₀ is with respect to the normal direction of the mask M ₀ When it is shifted around the x-axis by Δωx, the transfer shift Δyo in the y-axis direction is also expressed as follows.

Δyo = G · Δωx As an example, the proximity gap G = 30 μm, S
Assuming that the inclination Δωy of the optical axis of the RX line L ₀ is 0.5 mrad, the transfer deviation Δxo in the x-axis direction is 0.015
μm, which is unacceptable in a 256 MDRAM process requiring a line width of 0.25 μm and an overlay accuracy of 0.06 μm. In addition, as mentioned above,
Since the alignment optical system 103 is set in advance so that the alignment light A ₀ is incident on the mask M _{0 at} a predetermined angle, the optical axis O _{0 of the} SR-X-ray L ₀ is set to the mask M ₀
If it is not perpendicular to the surface of the
Generating a significant error in the detection of positional deviation of the substrate W ₀ by. Therefore, before the alignment by the alignment optical system 103, an operation of adjusting the attitude of the exposure chamber 101 is generally performed.

[0009]

However, according to the above-mentioned prior art, while irradiating SR-X-rays, the SR-X-rays pass through both pinholes of the pinhole member and are detected by the X-ray intensity sensor. Until the process of variously changing the posture of the exposure chamber by hand is required, the work time becomes long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides an exposure method and apparatus capable of quickly and accurately adjusting the position of an exposure chamber with respect to the optical axis of exposure light. It is intended for.

[0011]

According to the present invention, there is provided an exposure method comprising the steps of: holding a mask having an opening by a mask holder in an exposure chamber; Receiving light in a plane parallel to the mask and separated along an axis perpendicular to the mask, detecting the light receiving position, and tilting the axis with respect to the optical axis of the illumination light based on the detected light receiving position Calculating an angle, based on the calculated inclination angle,
Adjusting the verticality of the mask with respect to the mask .

Further, the exposure apparatus of the present invention comprises a mask having an opening which can be attached to a mask holder in an exposure chamber, and illuminating light passing through the opening provided in the mask along an axis perpendicular to the mask. received in spaced within the mask and parallel to the plane, a detecting means for detecting the light receiving position, the detected
An inclination angle of the illumination light with respect to an optical axis based on a light receiving position
Is calculated, and with respect to the optical axis based on the calculated inclination angle.
Adjusting means for adjusting the verticality of the mask .

[0013]

According to the above method, a mask having an opening such as a pinhole is held in a mask holder in an exposure chamber, and illumination light is applied to the mask and the illumination light passing through the opening is transferred along an axis perpendicular to the mask. The light is received within a plane parallel to the mask that has been separated away, and its light receiving position is detected. The detected light receiving position is
Compared to the case where the optical axis of the illumination light is parallel to said axis, Searching for the deviation, it calculates a tilt angle with respect to the optical axis of the illumination light of the shaft from the deviation. By adjusting the attitude of the exposure chamber based on the calculated tilt angle, the vertical
The degree can be adjusted quickly. Further, if the distance between the opening and the predetermined plane is increased, it is easy to further improve the accuracy.

[0014]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an exposure apparatus according to a first embodiment, which includes an exposure chamber 1 supported on a gantry 1a, and a light-emitting device (not shown) that emits light from a charged particle storage ring. beam duct 1b for introducing the SR-X-ray L ₁ is a charged particle storage ring synchrotron drawn from point
A beryllium window 1d provided in an opening 1c of the exposure chamber 1 which is open thereto, an alignment optical system 3 and a mask holder 4 supported by a support frame 2 integral with the inner wall of the exposure chamber 1, A known positioning stage 5 for attracting and positioning the wafer W ₁ on the chuck 5 a is provided, and by adjusting the attitude of the exposure chamber 1 , the verticality of the mask is adjusted.
Posture adjusting device 6 as an adjusting means for adjusting
A rotating device 6a for rotating the entire exposure chamber 1 around one axis (hereinafter, referred to as "y-axis") perpendicular to the gantry 1a, and a plurality of legs 6b provided between the gantry 1a and the floor surface. By adjusting the length of each footrest 6b, one axis perpendicular to the y-axis (hereinafter referred to as “x
Axis. Adjust the rotation angle around).

The positioning stage 5 by moving the x-axis and y-axis directions, which performs positioning of the wafer W _1, aligned with the X-ray intensity sensor 7 is detecting means on the side near the suction chuck 5a A reference member 8 having a mark 8a (shown in FIG. 2) is provided. The mask holder 4 holds the mask M ₁ perpendicularly to the z-axis which is a predetermined axis perpendicular to the x-axis and the y-axis. When exposing the wafer W ₁ with SR-X-rays L ₁ which is exposure light, The alignment optical system 3 detects a displacement between the mask M ₁ and the wafer W ₁ , and drives the positioning stage 5 based on the detected displacement to drive the mask M ₁ and the wafer W _1.
While performing the alignment, before that, the optical axis of SR-X-ray L ₁ must adjust the attitude of the exposure chamber 1 so as to be perpendicular to the mask M _1.

[0017] This task, as shown in FIG. 2, the pinhole mask 9 is a mask having an opening in the mask holder 4 instead of the mask M ₁ is mounted, SR-X-ray using an X-ray intensity sensor 7 This is performed by detecting the inclination angle of the optical axis of L ₁ and adjusting the attitude of the exposure chamber 1 by the attitude adjusting device 6.

The pinhole mask 9 has a pinhole 9a which is an opening at the center thereof. The X-ray intensity sensor 7 is movable with the positioning stage 5 in the x-axis direction and the y-axis direction. The light receiving surface is covered with an aperture member 10 as a second opening member having a pinhole 10a as an opening, and detects only light passing through the pinhole 10a. First, the positioning stage 5 is moved to a position where the X-ray intensity sensor 7 detects light that has passed vertically through the pinhole 9a of the pinhole mask 9 (hereinafter, referred to as “origin position”). SR-X which is illumination light
Moving the X-ray intensity sensor 7 within a predetermined plane parallel to the xy plane by the drive of the positioning stage 5 while irradiating the line L ₁ in the pinhole mask 9, passed through the pin hole 9a of the pinhole mask 9 SR- the X-ray L ₁ finds the light receiving position where the X-ray intensity sensor 7 is received, x-axis direction and the y-axis direction of the deviation Δx relative to the origin position at this time to determine the [Delta] y. Then the exposure chamber with respect to the optical axis of SR-X-ray L ₁ 1
Are calculated based on the following equation.

Ωx = Δy / D (1) ωy = Δx / D (2) where D: pinholes 9 a and X of pinhole mask 9
Distance between the light receiving surface of the line intensity sensor 7 Based on the inclination angles ωx and ωy detected in this manner, the attitude adjusting device 6 is driven to move the exposure chamber 1 in the z-axis direction and SR.
The optical axis of the -X-ray L ₁ is adjusted so as to be parallel.

According to the present embodiment, since the X-ray intensity sensor is moved to detect SR-X-rays, the inclination angle of the exposure chamber is obtained, and the attitude adjusting device is driven, the entire exposure chamber is driven. The SR-
The work is simpler than finding a posture in which the optical axis of the X-ray is parallel to the z-axis direction of the exposure chamber. Also, the separation distance D
If is increased, it is easy to detect even a small inclination angle.

For example, the distance D between the pinhole 9a of the pinhole mask 9 and the light receiving surface of the X-ray intensity sensor 7 is D = 50 m.
m, the diameter of each of the pinholes 9a, 10a of the pinhole mask 9 and the aperture member 10 is 5 μm,
The inclination angles ωx and ωy can be detected with a resolution of 0.1 mrad. Note that the smaller the diameter of the pinhole, the more difficult the operation of detecting the inclination angle of the exposure chamber becomes. Is desirably roughly detected.

As shown in FIG. 3, the alignment mark 1 is formed around the pinhole 9a of the pinhole mask 9.
9b, the positioning stage 5
By detecting the parallelism and the like of the pinhole mask 9 and correcting the output of the X-ray intensity sensor 7, the accuracy can be further improved.

Further, as shown in FIG. 4, if a plurality of second pinholes 29b are provided around the pinhole 9a of the pinhole mask 9, the runout amount around the exposure area is measured using this. You can also.

In place of the X-ray intensity sensor whose light-receiving surface is covered by the aperture member, a known four-division X-ray detector may be used, and the X-ray intensity sensor and the four-division X-ray detector may be positioned in this manner. Instead of moving the stage by driving the stage, a known position sensor such as a CCD camera or a PSD is fixed at a predetermined position, and the output of the position sensor is processed by a computer so that the SR-X-ray passing through the pinhole of the pinhole member can be used. If the light receiving position is detected,
The attitude of the exposure chamber can be detected more quickly.

As an example, when one resolution of the PSD is 1 μm, the distance between the PSD and the pinhole mask is 1 m.
If m or more, the angular resolution can be improved to 0.1 mrad.

FIG. 5 shows only a pinhole mask which is an aperture member according to the second embodiment and an aperture member of an X-ray intensity sensor which is a second aperture member. Instead of the pinhole 9a of one embodiment, the aperture 39a has a checker pattern, and the aperture member 40 of the X-ray intensity sensor also has the same checker pattern opening 40a.

In the same manner as in the first embodiment, the pinhole mask 39 is used.
Is mounted in the exposure room, and the X-ray intensity sensor is irradiated with SR-X-rays to scan the x-axis direction and the y-axis direction from the origin position, and the position where the output of the x-ray intensity sensor becomes maximum in each direction is determined. Then, deviations Δx and Δy from the origin position are obtained.
According to this embodiment, the SR-X-rays that have passed through the checker-patterned openings 39a of the pinhole mask 39 are detected through the checker-patterned openings 40a of the aperture member 40. X in one direction of
A deviation in the other direction can be estimated from a change in output when the line intensity sensor is scanned.

As an example, the entirety of the checker pattern opening 39a of the pinhole mask 39 and the checker pattern opening 40a of the aperture member 40 is a square having a side of 2 mm, and the distance between the pinhole mask 39 and the aperture member 40 is 50 mm. At some point, if the deviation Δy in the y-axis direction is zero, the output of the X-ray intensity sensor when the X-ray intensity sensor is scanned in the x-axis direction becomes a graph (a) shown by a solid line in FIG. Is 0.5 mm, a graph (b) shown by a broken line is obtained.
If it is 25 mm, a graph (c) shown by a one-dot chain line is obtained.
As described above, since the deviation in the other direction can be estimated from the pattern of the output change when the X-ray intensity sensor is scanned in one direction, the number of scans of the X-ray intensity sensor can be greatly reduced.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 7 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel, a CC)
D, thin-film magnetic head, micromachine, etc.). In step 101 (circuit design), a circuit of a semiconductor device is designed. Step 102 (mask production)
Then, a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 103 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 104
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 105 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer prepared in step 104, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 106 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 105 are performed. Through these steps, a semiconductor device is completed and shipped (step 107).

FIG. 8 shows a detailed flow of the wafer process. Step 111 (oxidation) oxidizes the wafer's surface. Step 112 (CVD) forms an insulating film on the wafer surface. In step 113 (electrode formation), electrodes are formed on the wafer by vapor deposition. Step 114
In (ion implantation), ions are implanted into the wafer. In step 115 (resist processing), a photosensitive agent is applied to the wafer. In step 116 (exposure), the circuit pattern of the mask is printed onto the wafer by exposure using the above-described exposure apparatus. In step 117 (developing), the exposed wafer is developed. In step 118 (etching), portions other than the developed resist image are removed. In step 119 (resist removal), unnecessary resist after 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 conventionally difficult to manufacture.

[0031]

Since the present invention is configured as described above, it has the following effects.

The attitude of the exposure chamber with respect to the optical axis of the exposure light can be quickly adjusted with high precision. As a result, it is easy to adjust the verticality of the mask with respect to the exposure light and the like, and it is possible to realize an exposure apparatus with little transfer deviation and high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an exposure apparatus according to a first embodiment.

FIG. 2 is a perspective view showing only a pinhole mask, an X-ray intensity sensor, and a positioning stage of the apparatus of FIG.

FIG. 3 is a plan view showing a pinhole mask provided with an alignment mark.

FIG. 4 is a plan view showing a pinhole mask provided with a second pinhole.

FIGS. 5A and 5B show only a pinhole mask and an aperture member of an X-ray intensity sensor according to a second embodiment, wherein FIG. 5A is a cross-sectional view showing a pinhole mask and FIG. FIG.

FIG. 6 is a graph showing a change in the output of the X-ray intensity sensor of the second embodiment.

FIG. 7 is a sequence diagram showing a semiconductor device manufacturing process.

FIG. 8 is a sequence diagram showing a wafer process.

FIG. 9 is a schematic sectional view showing a conventional example.

FIG. 10 is a diagram illustrating a transfer deviation when the exposure light does not perpendicularly enter the mask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exposure room 3 Alignment optical system 4 Mask holder 5 Positioning stage 6 Attitude adjuster 7 X-ray intensity sensor 9, 39 Pinhole mask 9a, 10a, 29b Pinhole 10.40 Aperture member 39a, 40a Opening of checker pattern

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (10)

(57) [Claims] 1. A step of holding a mask having an opening by a mask holder in an exposure chamber, and illuminating light passing through the opening in a plane parallel to the mask and separated from the opening along an axis perpendicular to the mask. Detecting the light receiving position, and calculating an inclination angle of the axis with respect to the optical axis of the illumination light based on the detected light receiving position.
And, based on the calculated inclination angle, with respect to the optical axis.
Adjusting the verticality of the mask . 2. The method according to claim 1, further comprising the step of adjusting the posture of the exposure chamber based on the calculated inclination angle.
Exposure method according to the above. 3. A mask having an opening attachable to a mask holder in an exposure chamber, and illuminating light passing through the opening provided in the mask being parallel to the mask separated from the mask along an axis perpendicular to the mask. Detecting means for receiving light in a plane and detecting the light receiving position;
Calculate the tilt angle of the bright light with respect to the optical axis, and calculate the calculated tilt angle
Adjustment of the perpendicularity of the mask to the optical axis based on the degree
An exposure apparatus , comprising: adjusting means for performing adjustment . 4. An exposure apparatus according to claim 3, wherein said detecting means is an X-ray intensity sensor movable in a predetermined plane. 5. The detecting means is a CCD camera or a PSD.
The exposure apparatus according to claim 3, wherein 6. An exposure apparatus according to claim 4, wherein said detecting means has an aperture member on a light receiving surface thereof. 7. The exposure apparatus according to claim 6, wherein the mask and the opening member have at least one opening, and this is a pinhole. 8. The exposure apparatus according to claim 6, wherein the mask and the opening member have a checker pattern opening. 9. adjusting means, claims 3 to 8 exposure apparatus according to any one of the preceding wherein Rukoto to have a posture adjusting device for adjusting the attitude of the exposure chamber on the basis of the output of the detection means. 10. The exposure method according to claim 1, wherein an alignment mark is provided on the mask.