JPH0273618A - Aligner - Google Patents

Abstract

PURPOSE:To reduce in size an aligner and to improve its reliability by integrally mounting a blade for limiting an exposure beam at an alignment unit for detecting the deviation of a wafer and an alignment mark on a mask. CONSTITUTION:An alignment unit AAU is secured to a supporting member SPT, an alignment beam ABM is emitted to an alignment mark AMK on a mask MSK, and a deviation of the mark AMK on a wafer is detected. A blade BLD is secured to a predetermined position of a member PST through an arm ARM. Thus, the unit AAU and the blade BLD are integrally moved when an exposure beam EXB is exposed, and moving positioning means exclusive for the blade BLD is eliminated. Accordingly, an aligner can be reduced in size, and its reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure apparatus that prints a pattern on an original onto an opposing substrate using an exposure beam. Furthermore, the present invention relates to an exposure apparatus that is designed to be smaller and have improved reliability by providing a cooling means.

[Prior Art] In exposure equipment used in semiconductor manufacturing, etc., a pattern drawn on an original called a mask or reticle is projected onto a substrate such as a wafer or glass using an exposure beam, and then the pattern is printed onto the substrate. A process is performed in which the applied resist is exposed and transferred according to the pattern. In this case, means may be provided to limit the exposure beam so that an unnecessary portion of the exposure beam irradiated onto the mask or reticle does not reach the mask or reticle.

For example, in the exposure of integrated circuit patterns, alignment marks for aligning the mask and wafer are placed on lines with a width of 50 to 100 μm called scribe lines around square or rectangular circuit patterns. If the entire surface of such a mask is irradiated with an exposure beam, not only the circuit pattern but also the alignment mark on the scribe line will be burned onto the wafer in the same way as the circuit pattern. To avoid this, a method is generally used in which the scribe line is covered with a blade having a straight edge to prevent the exposure beam from hitting the scribe line.

In particular, in X-ray exposure equipment, unlike other exposure equipment, the light that is irradiated onto the mask is not reflected but is absorbed by the mask and exchanged with heat, causing distortion, so that unnecessary light is removed from the mask as much as possible. It is common to provide means for limiting the exposure beam so that it is not irradiated.

[Problems to be Solved by the Invention] However, in the above conventional example, since the area where the exposure beam should be restricted changes depending on the size of the circuit pattern,
It is necessary to move and position the blade according to the size of the circuit pattern.

That is, a guide mechanism for moving the blade eight times in a certain direction and an actuator for driving the guide mechanism are required, and the configuration of the entire device becomes complicated.

In addition, since the above positioning requires high precision,
A guide mechanism with high rigidity and high straightness and a position detection means with high resolution are required, which increases the weight and cost of the device.

In addition, in X-ray exposure equipment, by providing a blade that limits the exposure beam as in the past, it is possible to suppress the temperature rise due to the absorption of exposure beam energy by the mask itself, but on the other hand, the blade that limits the exposure beam The temperature will rise. In particular, in exposure apparatuses that require highly accurate alignment, not only thermal distortion of the mask but also slight thermal distortion of the apparatus components poses a problem, so it is also necessary to suppress the temperature rise of this blade.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, an object of the present invention is to provide an exposure apparatus that has a simple configuration, effectively limits the exposure beam, and solves the problem of temperature rise.

[Means and effects for solving the problem] To achieve the above object, the exposure apparatus of the present invention includes an exposure device that transfers a pattern of an original onto a substrate, and a deviation that detects a deviation between alignment marks on the original and the substrate. The apparatus comprises a detection means, a positioning means for positioning the deviation detection means, and an exposure beam limiting means for limiting the exposure beam emitted by the exposure means, and the exposure beam limiting means is attached integrally to the deviation detection means. I have to.

Further, four of the displacement detecting means are arranged so that their directions are different from each other by 90 degrees, and the exposure beam limiting means includes a plate-like member having a linear edge portion that limits the exposure beam, and the exposure beam emitted by the exposure means The distance along the optical axis of the exposure beam from the origin of the divergence angle of the beam and the edge of the plate member to the original is LM and LA%, respectively, one side of the minimum angle of view limited by the exposure beam limiting means. If the length of is It min, the plate member is fixed to the shift detecting means so that the amount of protrusion of the edge inward of the exposure angle of view is equal to or less than LAxILmin/(2·LM).

Further, the exposure beam limiting means includes a minute movement means for moving the plate member by a minute amount in a direction perpendicular to the edge portion,
It also includes cooling means.

According to this, the deviation detecting means for detecting the amount of lateral deviation of the opposing original and substrate and the exposure beam limiting means are:
During exposure, they are moved integrally by the positioning means.

Therefore, there is no need to provide a moving positioning means exclusively for the exposure beam limiting means. Furthermore, since the exposure beam limiting means is positioned with respect to the alignment mark of the deviation detection means, which is regulated by law, the exposure beam limiting means can be positioned at an appropriate position with high precision according to the angle of view. . Furthermore, in the present invention, since the exposure beam limiting means is provided with a cooling means, the exposure beam
Even in the case of a line, there is no temperature rise in the exposure beam limiting means, and a highly accurate alignment environment can be obtained.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a perspective view showing the main parts of an exposure apparatus according to an embodiment of the present invention, and best represents the features of the present invention. In the same figure, MSK is a mask, SLN is a pattern corresponding to the scribe line of mask MSK, and AMK is a pattern SLN.
The upper alignment mark ABM is an alignment beam, and AAU 1 projects an alignment beam ABM onto the alignment mark AMK, and aligns the alignment mark on the wafer (not shown) and the alignment mark A on the mask MSK.
Alignment unit, SPT that detects misalignment with MK
is a support member to which the alignment unit is fixed. , LD is a housing part for a semiconductor laser which is a light source of alignment beam ABM, and SEN is a housing part for a light receiving sensor that converts an optical deviation signal returned from alignment mark AMK into an electric signal. Optical components such as a collimator lens, a beam splitter, and a light receiving lens are housed within the alignment unit AAUI. B
The LDI is a blade that limits the irradiation area of the mask MSK of the exposure beam EXB irradiated from the direction of the arrow in the figure. Blade BLDI is fixed to support member SPT via arm ARM. Further, the blade BLDI is provided with cooling pipes CLI and CLO, and a cooling pipe path is formed within the blade.

STG is a stage unit composed of orthogonal two-axis guide and drive means and position detection means. Support member SPT is coupled to this stage unit STG, and alignment beam ABM is positioned at alignment mark AMK on the mask. It is configured so that it can be done.

In an actual system, although not shown, four units having the same series of configurations as described above are provided corresponding to the alignment marks AMK on each of the four scribe lines. Therefore, one exposure device has four blades (
BLDI to BLD4) and four alignment units (
AAUI to AAU4) are attached. In the following description, unless a specific one of these four is specified, the symbol BLD will be used for the blade and the symbol AAIJ will be used for the alignment unit.

FIGS. 2(A) and 2(B) are diagrams schematically showing the relationship between the configuration shown in FIG. 1 and an exposure beam from a lateral direction.

As shown in the figure, the exposure beam EXB is a diverging beam having a divergence angle θ starting from point 0, and in this embodiment, X-rays are used. The exposure beam EXB is initially exposed to a fixed aperture FAP.
As shown in the figure, the exposure beam becomes EXBF.

In FIG. 2(A), fl yrax indicates the maximum exposure angle of view in this device, and the aperture size of the fixed aperture FAP is such that the exposure beam EXB It has been decided to irradiate slightly outside. The exposure beam EXBF that has passed through the fixed aperture FAP is further transferred to an alignment unit A.
Limited by the blade BLD fixed on the ALI.

FIG. 3 shows the arrangement of the blades provided on each alignment unit AAU when viewed from the light source side. Adjacent blades have different heights and do not interfere with each other regardless of the angle of view size.

In such a configuration, the relationship between the field angle size and the blade attachment position will be described.

Figure 2 (A) shows the spot SPT of the alignment beam ABM on the scribe line in the case of the maximum image Qj2max.
(B) shows the state in which the minimum angle of view fl is accessed.
Alignment beam A on the min scribe line
This shows a state where the BM spot SPT is accessed. At this time, each blade is fixed to the alignment unit AAU so that the exposure beam is irradiated to just outside the outer edge of the scribe line.

When the position is expressed as the amount of protrusion of the blade from the outer edge of the scribe line inward toward the angle of view, it is dmax in FIG. 2A and d min in FIG. The protrusion amount d of the plate BLD is the angle of view size of 1,
The distance from the origin 0 of the exposure beam with the divergence angle to the mask MSK. , Mask M from Edge of Blade BLD
If the distance to SK is LA, then (i) d=LAX2L.

Therefore, d max and d mi
Each n is λmax (ii) dmaX=LAx2LM λmin (iff) dmtn”t, Ax2L, For example, LA=150mm, L,=g5000m
m, Ilmax = 30mm, jZmin =
If 15 mm, d max = 0.45 mm,
d min = 0.225 n++n. Considering the role of the edge of the blade BLD, it is preferable to set it so as to block light as much as possible near the outer edge of the scribe line. However, when the blade is set for the maximum angle of view, as shown in Fig. 4. As the light-shielding area extends to the inside of the angle of view, the required angle of view cannot be obtained. Therefore, alignment unit A
When fixing the blade BLD to the AU, the minimum angle of view λ
It is sufficient to set min as a condition, and the protrusion amount d is equal to or less than LAxJZmin/(2·L, ).

By setting the position of the blade BLD in this way and fixing it on the alignment unit AAU, the position of the blade can be moved to an appropriate position according to the angle of view size without providing a special positioning means for the blade. Is possible.

Since the alignment mark AMK and the alignment beam spot SPT are aligned with a high precision of less than 10 μm on the shell, the blade positioning precision is naturally high, and most of the unnecessary exposure beam that you do not want to irradiate onto the mask can be removed. It is possible to block light with a blade.

Cooling of the blade BLD will be explained using FIGS. 5 and 6. In Figure 5, TNKl and TNK
2 are cooling water tanks whose temperatures are controlled at 23.5°C and 10°C, respectively.

On the way, the cooling water from the cooling water tank TNKI exchanges heat with the cooling water from the cooling water tank TNK2 in the heat exchanger TEX, and the temperature is adjusted to T5°C, which is lower than 23.5°C. After passing through the pipe CLP, the water returns to the cooling water tank TNKI. Cooling water tank TNKI
, TNK2, and the heat exchanger are installed in a sufficiently accessible location that is not thermally affected by the unit performing alignment.

TSNI and TSNO are temperature sensors provided near the port and outlet of the piping inside the blade BLD, respectively, and use platinum thin film resistance elements or thermistors. Information from these temperature sensors is sent to the controller CNT, and the proportional control valve L
This is used as data to control the opening degree of the NV. The proportional control valve LNV always supplies a constant amount of water from the cooling water tank TNK2.
The controller CNT controls the ratio of the amount of cooling water that flows to the bypass pipe BP side and the amount that flows to the heat exchanger TEX side, and controls the temperature TB°C of the cooling water sent to the piping in the blade BLD. The temperature is controlled to the set temperature.

Next, a case where an exposure beam is irradiated in the above configuration will be described.

Since the exposure beam is generally irradiated onto the mask for a certain period of time by a shutter etc., the blade BLD also follows the curve L1 in FIG.
generates thermal energy as shown in For example, when the exposure time is 1 second, the energy absorbed by the blade BLD is 5 seconds.
At 0 mJO, to flow cooling water at a constant temperature of 23°C at a constant flow rate and suppress the temperature rise to about 1/100°C, approximately 1.2
A flow rate of cc/sec may be applied. Also, from the perspective that cooling is required only during exposure, the curve L in Figure 6
As shown in 3, it is also effective to synchronize the temperature of the cooling water with the exposure timing and keep it below 23°C. As shown in Figure 5, this is the signal S from the main controller.
This is possible by controlling the controller CNT in accordance with the exposure timing using IN. Blade B
The energy absorbed by the LD changes depending on the size of the field of view and the light source intensity. For example, if exposure is performed with a constant flow of cooling water at a constant temperature of 23°C, the Since a temperature change as shown by the curve L2 in FIG. 6 can be observed, a control table for the proportional control valve LNV can be created based on this data.

As explained above, according to this embodiment, even in a state where it is difficult to reflect an X-ray exposure beam, the energy is absorbed by the blade and converted into heat, and then the cooling water is used to
Since it is configured to be carried out of the apparatus, it is possible to suppress the propagation of heat to the vicinity of the blade and to achieve highly accurate alignment.

Further, in this example, the temperatures of the two types of cooling water were set to 23.5° C. and 10° C., respectively, but the present invention is not limited to this. In addition, from the perspective of suppressing heat conduction from the blade BLD to other components, temperature control can be more easily achieved by using a material with low thermal conductivity, such as ceramics, for the blade BLD mounting part. It is possible.

Next, other embodiments of the present invention will be described.

FIG. 7 shows a portion corresponding to the blade BLD provided with the cooling pipe connector in FIG. 1, viewed from the light source side. Unlike FIG. 1, behind the blade BLD, a parallel link PLK and an inch worm INC are connected in series via a rod ROD. This unit is mounted on the alignment unit AAU by four screws SCR.

In the embodiment shown in FIG. 1, in the case of an exposure beam having a divergence angle, as the angle of view becomes smaller, the edge ED of the blade BLD fixed on the alignment unit AAU becomes smaller.
Because the inner edge of the light-shielding area formed by Regardless of the size, in order to keep the distance between the inner edge of the light-shielding area formed by the edge EDG and the outer edge of the scribe line constant, the amount of protrusion of the blade should be determined by considering the relationship in equation (i). Needs to be corrected. According to the numerical example in the above-mentioned embodiment, the amount is as follows regarding the protrusion amount d: dmin=0.225 mm, dmax=
Since it is 0.451Qm, the difference is 0.225 mm
This amount is the stroke required to correct the blade protrusion amount in consideration of the angle of view size.

In this embodiment, since the actuator is an inch worm and the guide mechanism is a parallel link PLK, it is possible to obtain a sufficient stroke and accuracy necessary for correction. Further, since the parallel link PLK has no sliding portion, no particles are generated. Furthermore, since the inch worm ING used in the actuator hardly generates heat after positioning, it does not have any adverse effect on other components.

FIG. 8 shows another example of a mechanism for correcting the amount of protrusion of the blade, and shows the blade BLD viewed from the side. In the figure, BO is a common rotation center of the blade BLD and the worm wheel WH, and the edge EDG of the blade BLD is configured to rotate around this point by the rotation of a small motor MTR equipped with a speed reducer.

In such a configuration, the edge ED of the blade BLD
Assuming that the distance from G to the center of rotation BO is 1=200 m, and the stroke required for correction is 0.225 mm, which is the same as above, the necessary stroke can be calculated by rotating the blade BLD by approximately 8.6 degrees with the inclination angle θ. You can get a stroke.

In this example, we do not use an expensive linear guide and use a blade BLD.
By rotating and supporting the edge EDG, it is possible to change the protruding position of the edge EDG relative to the exposure beam.

Since the unnecessary irradiation area of one frame is minimized and no light is blocked within the pattern for any angle of view size, unnecessary energy absorbed by the original plate can be minimized.

In addition, since the exposure beam limiting means is provided with a cooling means and the unnecessary exposure energy absorbed by the exposure beam limiting means is carried out to the outside of the apparatus, thermal distortion does not occur, and alignment accuracy is improved. It is also effective in making exposure patterns finer.

[Effects of the Invention] As explained above, according to the present invention, the means for detecting the amount of deviation between the substrate and the original and the means for restricting the exposure beam are integrated, and the structure is configured for legal positioning. This eliminates the need for positioning means dedicated to the exposure beam limiting means, which is effective in reducing the size of the apparatus and improving reliability.

In addition, when integrating the exposure beam limiting means with the deviation amount detecting means, it is necessary to

[Brief explanation of the drawing]

1 is a perspective view showing the main parts of an exposure apparatus according to an embodiment of the present invention, and FIGS. 2(A) and 2(B) are horizontal views showing the relationship between the configuration shown in FIG. FIG. 3 is a schematic diagram showing the arrangement of the blades provided on each alignment unit of the apparatus in FIG. 1, viewed from the light source side; FIG. An explanatory diagram for explaining the operation of the apparatus shown in FIG. 2 in relation to FIG. 2, FIG. FIG. 7 is a plan view of a main part of another embodiment of the present invention, and FIG. 8 is a side view of a main part of still another embodiment of the present invention. Figure 7 BLD, BLDI, BLD2 Niblade, AAU, AA
UI, AAU2: Alignment unit, ABM: Alignment beam, MSK: Mask, STG Nistisch knit, CLI, CLO: Cooling piping. Figure 8 T'C TC

Claims (4)

[Claims] (1) exposure means for transferring the pattern of the original onto the substrate;
comprising: a displacement detection means for detecting a displacement between alignment marks on an original and a substrate; a positioning means for positioning the displacement detection means; and an exposure beam restriction means for restricting an exposure beam emitted by the exposure means; An exposure apparatus characterized in that the means is integrally attached to the deviation detecting means. (2) The four displacement detection means are arranged so that their directions differ by 90 degrees from each other, and the exposure beam restriction means includes a plate-like member having a linear edge portion that restricts the exposure beam, and the exposure beam is emitted by the exposure means. The distance along the optical axis of the exposure beam from the starting point of the divergence angle of the exposure beam and the edge of the plate-like member to the original is L_M and L_A, respectively, and one side of the minimum angle of view limited by the exposure beam limiting means is L_M and L_A, respectively. If the length is lmin, the plate member is fixed to the shift detection means so that the amount of protrusion of the edge inward of the exposure angle of view is equal to or less than L_A×lmin/(2·L_M); An exposure apparatus according to claim 1. (3) The four deviation detection means are arranged so that their directions differ from each other by 90 degrees, and the exposure beam limiting means includes a plate-like member having a linear edge portion that limits the exposure beam, and a plate-like member that controls the plate-like member. 2. The exposure apparatus according to claim 1, further comprising a minute movement means that moves a minute amount in a direction perpendicular to the edge portion. (4) The exposure apparatus according to claim 1, wherein the exposure/beam limiting means is provided with a cooling means for cooling it.