JP2005228978A - Exposure device and manufacturing method for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the alignment accuracy of an exposure device. <P>SOLUTION: The exposure device performs the projection transfer of a pattern drawn on a reticle 6 via a reduction projection lens 3 at a wafer 4A. This exposure device is provided with an elastic seal 7C having a support face which supports reticle 6 by that periphery, and a reticle clamp pad 7A which supports the elastic seal 7C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and a method for manufacturing a semiconductor device used in a semiconductor manufacturing process, and more particularly to a support for a master and a substrate.

  As patterns of semiconductor integrated circuits and the like become denser and finer, further improvement in alignment accuracy of an exposure apparatus is required. Various factors are considered as factors for lowering the alignment accuracy of the exposure apparatus.

  For example, the thermal expansion of the reticle due to the exposure light and the thermal deformation of the peripheral portion thereof can cause a decrease in alignment accuracy and a deterioration in imaging performance. In order to solve this problem, a reticle or an object having high thermal conductivity / thermal diffusivity is provided on a reticle or a support portion of the reticle to eliminate heat, diffuse or equalize, or make a predetermined distribution (for example, (See Patent Document 1).

  In addition, due to deformation of the reticle due to its own weight, deformation of the reticle surface, deformation of the reticle surface during clamping, etc., the pattern on the reticle surface may change the curvature of field on the wafer upper surface, pattern lateral deviation, distortion, and in-pattern deformation. Focusing or the like may occur, and the pattern resolution may deteriorate. In order to solve this problem, there is a technique that detects the displacement of the reticle surface, and based on the detection result, displaces a member that fixes the reticle to correct the deformation of the reticle surface (see, for example, Patent Document 2). ).

  In addition, a mask support base is disclosed in which the mask is abutted and supported by four support surfaces, and the two support surfaces are swung at the support center of the two support surfaces (see, for example, Patent Document 3).

  Further, a fixing device is disclosed in which a material to be processed is held by a holding member having a guide mechanism, and the material to be processed is moved up and down by the guide mechanism and positioned on a moving stage (see, for example, Patent Document 4). .

In addition, a fixing device that improves the flatness by supporting the inside of the lower surface of the material to be processed with a coil spring and clamping the end of the material to be processed is disclosed (for example, see Patent Document 5).
JP 2001-035764 A JP 2001-148335 A JP 07-326666 A Japanese Patent Laid-Open No. 08-288371 Japanese Patent Laid-Open No. 08-167553

  However, in the conventional techniques such as Patent Documents 1 and 2, it is difficult to suppress a decrease in alignment accuracy due to foreign matter entering between the reticle and its support surface. This will be described with reference to FIGS.

  FIG. 13 is a diagram showing the configuration of a conventional exposure apparatus. The reticle 101 is an original of an exposure pattern. The reticle stage 102 mounts the reticle 101 and scan-exposes the reticle 101 to exposure light (not shown). The reticle clamp 103 is made of ceramic, and clamps the reticle 101 to the reticle stage 102. The reduction projection lens 104 reduces and projects the pattern on the reticle 101 onto the substrate (wafer) 105. The wafer stage 106 mounts a wafer 105 such as a silicon substrate, and performs scanning movement exposure with respect to exposure light in synchronization with the reticle stage 102.

  FIGS. 14A and 14B are a top view (FIG. 14A) and a side view (FIG. 14B) of the reticle stage 102 of FIG. As shown in FIGS. 14A and 14B, reticle 101 is clamped to reticle stage 102 by reticle clamp pad 103 </ b> A of reticle clamp 103.

  FIG. 15 is an enlarged view of the reticle clamp 103 of FIG. As shown in FIGS. 15A and 15B, the reticle 101 is vacuum-adsorbed by the pump 12 through the exhaust hole 11 connected to the recess 10 of the reticle clamp pad 103A.

  As shown in FIG. 15A, in such a reticle stage 102, when the reticle 101 is clamped, a foreign substance 103B may be sandwiched between the upper surface (clamp surface) of the reticle clamp pad 103A and the reticle 6. . As a result, when a pattern on the surface of the reticle 101 is projected onto the wafer, there is a problem that defocus in the pattern surface is deteriorated and pattern accuracy on the wafer is lowered.

  Further, in Patent Document 3, when dust is present on the mask surface, the mask is rocked and supported to make the deflection shape constant, but the mask surface moves due to the presence of dust, and defocus in the pattern surface is reduced. The problem of getting worse is inevitable.

  Similarly, when the substrate is clamped on the stage, the deterioration of the flatness of the chuck causes the curvature of field, the lateral displacement of the pattern, the distortion, the deterioration of the defocus in the pattern surface, and the like, and the pattern accuracy on the substrate deteriorates. There is a problem.

  For example, Patent Document 4 requires a separate lifting mechanism for the material to be processed, which complicates the holder device and avoids deterioration in drawing accuracy when dust is placed on the contact surface with the material to be processed. Absent.

  Moreover, in patent document 5, although the mask scissors which hold the edge part of a mask blank are elastically supported by the spring, since the edge part of a mask blank is mechanically held by the mask scissors, the edge part of a mask blank There is a problem that stress is applied.

  Further, in the conventional reticle clamp, the support surface is formed of ceramic, and due to the instability of the contact surface between the ceramic support surface and the original plate and the instability of the friction coefficient, a slight deviation occurs when the original plate moves. There is also a problem.

  The present invention has been made in view of the above background, and an object thereof is to improve the alignment accuracy of an exposure apparatus.

  A first aspect of the present invention relates to an exposure apparatus that projects and transfers a pattern drawn on an original onto a substrate via a projection optical system, and has an elastic surface having a support surface that supports the original or the substrate at its peripheral portion. And a support member that supports the elastic member.

  A second aspect of the present invention relates to a projection exposure apparatus that projects and transfers a pattern drawn on an original onto a substrate via a projection optical system, and a metal thin film layer having a support surface that supports the original or the substrate; And a support member that supports the elastic member.

  According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device, the application step of applying a photosensitive material to a substrate, and the exposure apparatus described above applied to the substrate on which the photosensitive material is applied in the application step. An exposure process for transferring a pattern; and a development process for developing the photosensitive material on the substrate onto which the pattern has been transferred in the exposure process.

  According to the present invention, the alignment accuracy of the exposure apparatus can be improved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In the following embodiments, a reticle stage of an exposure apparatus will be described as an example, but the present invention is not limited to this. The invention according to a preferred embodiment of the present invention can be similarly applied to, for example, a wafer stage of an exposure apparatus.
[First embodiment]
FIG. 1 is a conceptual diagram showing a configuration of an exposure apparatus according to a preferred embodiment of the present invention.

  The illumination system unit 1 guides exposure light from the light source as uniform exposure light. The reticle stage 2 is equipped with an exposure original (reticle), and scan exposure of the original (reticle) is performed with respect to the exposure light guided by the illumination system unit 1. The reduction projection lens 3 reduces and projects an original (reticle) pattern mounted on the reticle stage 2 onto the wafer. The wafer stage 4 mounts a wafer (see 4A in FIG. 3) containing a semiconductor material such as silicon or a compound semiconductor. The wafer stage 4 can perform scan exposure by scanning and moving the exposure light in synchronization with the reticle stage 2. The exposure apparatus main body 5 supports the reticle stage 2, the reduction projection lens 3, the wafer stage 4, and the like.

  2 to 5 are conceptual diagrams showing in detail the configuration of the reticle stage 2 of FIG.

  FIG. 2 is a perspective view of the reticle stage 2 of FIG. The reticle stage 2 holds the reticle 6 on a reticle clamp (not shown). An exposure pattern is formed on the reticle (original plate) 6. On both sides of the reticle 6, linear motor movable elements 201a and 201b are arranged. The linear motor movable elements 201a and 201b constitute linear motors with the linear motor stators 202a and 202b, and drive the reticle 6 in the scanning direction.

  FIG. 3 is a conceptual diagram showing in detail the configuration of the exposure apparatus of FIG. The reticle stage 2 includes a reticle clamp 7 as a support member that supports the reticle 6. On the reticle clamp 7, an elastic seal 7C having a support surface for supporting the reticle 6 at its periphery is disposed.

  FIG. 4 is a top view (FIG. 4A) and a side view (FIG. 4B) of the reticle stage 2. FIG. As shown in FIG. 4A, slit-shaped exposure light 8 passes through the reticle pattern of the reticle 6.

  5 and 6 are conceptual views showing in detail the structure for positioning and holding the reticle 6.

  FIG. 5A is a top view of the reticle stage 2. The reticle 6 is positioned and held on the upper surface of the reticle clamp pad 7A. FIG. 5B is a sectional view of the reticle stage 2 in the state of FIG. The reticle clamp pad 7A has a recess 10a formed on the upper surface. An elastic seal 7C is disposed on the outer periphery 10b of the recess 10a. An exhaust hole 11 is provided in the recess 10a. The reticle 6 is adsorbed by the pump 12 connected to the exhaust hole 11. The elastic seal 7C performs the sealing function of such a suction mechanism. As the elastic seal C, for example, a fluorine-based resin or a polyparaxylene resin can be used.

  FIG. 6 is a conceptual view showing the reticle clamp pad 7A in detail. As shown in FIGS. 6A and 6B, a plurality of pins 7B as protrusions are arranged in the recess 10a of the reticle clamp pad 7A. The pin member 7B may have any shape as long as the reticle 6 can be positioned. The height of the pin 7B is such that when the reticle 6 is clamped by the vacuum pressure Vac of the pump 12 and the elastic seal 7C is elastically deformed and closely contacts the lower surface of the reticle 6, the tip of the pin 7B hits the lower surface of the reticle 6. Adjusted to position at position. In this way, the vertical position of the reticle 6 is determined by the pin 7B.

  The elastic seal 7C preferably has an elastic coefficient in a direction perpendicular to the support surface on which the reticle 6 is supported by the reticle clamp pad 7A smaller than an elastic coefficient in the direction horizontal to the support surface. The reticle clamp pad 7A or the elastic seal 7C is elastically supported so that the elastic coefficient in the direction perpendicular to the support surface on which the reticle 6 is supported by the reticle clamp pad 7A is smaller than the elastic coefficient in the horizontal direction on this support. It is desirable that

  With the above-described configuration, even when a minute foreign matter adheres to the elastic seal 7C on the upper surface of the reticle clamp pad 7A, the elastic seal member is deformed to cause distortion on the reticle 6 due to the foreign matter, or a vacuum leak. Etc. can be avoided.

  In addition, the pin portion 7B provided in the concave portion has a configuration in which a plurality of micro pins with a very small contact area are arranged, so that the probability that foreign matter is interposed between the reticle 6 and the pin portion 7B can be extremely reduced. become. As a result, the frequency of occurrence of distortion on the reticle 6 due to foreign matter can be greatly reduced.

  The wafer stage 4 also has a configuration in which a recess is formed on the surface of a wafer pad that vacuum-sucks the wafer, and an elastic seal is disposed on the outer periphery of the recess, similarly to the reticle stage 7A according to the present embodiment. Can do. Hereinafter, the reticle stage is described as an example in other embodiments as well, but can be applied to the wafer stage 4 in the same manner.

As described above, according to the present embodiment, when a foreign object adheres between the reticle surface and the reticle support surface, the support surface is made an elastic member so that the minute foreign material is buried within the thickness of the elastic member. Can do. As a result, reticle distortion due to foreign matter can be prevented, reticle deformation can be suppressed directly, and the exposure accuracy can be improved.
[Second Embodiment]
FIG. 7 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred second embodiment of the present invention. The reticle clamp pad 7A of the present embodiment is generally the same as the reticle clamp pad 7A according to the first embodiment shown in FIG. However, it differs from the structure of 1st Embodiment by the point comprised so that the elastic seal | sticker 7C can be attached or detached. Other configurations are substantially the same as those in the first embodiment, and thus the description thereof is omitted in the second embodiment.

  FIG. 7 exemplarily shows a configuration in which the reticle 6 is positioned and held on the reticle clamp pad 7A on the reticle stage 2. FIG. 7A is a top view of the reticle clamp pad 7A, and FIG. 7B is a cross-sectional view of the reticle clamp pad 7A. An elastic seal bracket joint surface 7E as a depression is formed around the upper surface of the reticle clamp pad 7A. An elastic seal 7C having a vacuum clamp sealing function by the pump 12 is provided on the elastic seal bracket joint surface 7E. As shown in FIGS. 7A and 7B, a plurality of pins 7B as protrusions are arranged on the upper surface of the reticle clamp pad 7A. The height of the pin 7B is such that when the reticle 6 is clamped by the vacuum pressure Vac of the pump 12 and the elastic seal 7C is elastically deformed and closely contacts the lower surface of the reticle 6, the tip of the pin 7B hits the lower surface of the reticle 6. Can be adjusted to position. In this way, the vertical position of the reticle 6 can be determined by the pin 7B.

With the configuration as described above, according to the present embodiment, even when a foreign substance adheres to the elastic seal 7C and a vacuum leak or the like occurs due to the influence of the foreign substance, as shown in FIG. The elastic seal bracket 7D to which the elastic seal 7C is bonded can be removed from the other and easily replaced with another elastic seal bracket 7D.
[Third embodiment]
FIG. 9 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred third embodiment of the present invention. The reticle clamp pad 7A of the present embodiment is generally the same as the reticle clamp pad 7A according to the second embodiment shown in FIG. However, this is different from the configuration of the second embodiment in that an elastic sheet 7F or an elastic foam sheet 7G is provided in a recess on the upper surface of the reticle clamp pad 7A. The other configurations are substantially the same as those in the second embodiment, and thus the description thereof is omitted in the third embodiment.

  FIG. 9 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred third embodiment of the present invention. FIG. 9 exemplarily shows a configuration in which the reticle 6 is positioned and held on the reticle clamp pad 7A on the reticle stage 2. 9A is a top view of the reticle clamp pad 7A, and FIG. 9B is a cross-sectional view of the reticle clamp pad 7A in FIG. 9A (cross section taken along AA in FIG. 9A). FIG. 10 is a cross-sectional view taken along line BB in FIG. 9 and FIG. An elastic seal 7C having a vacuum clamp sealing function is provided around the upper surface of the reticle clamp pad 7A.

  Also, as shown in FIGS. 9A and 9B, a plurality of pins 7B serving as protrusions are arranged in the recesses on the upper surface of the reticle clamp pad 7A. The height of the pin 7B is such that when the reticle 6 is clamped by the vacuum pressure Vac of the pump 12 and the elastic seal 7C is elastically deformed and closely contacts the lower surface of the reticle 6, the tip of the pin 7B hits the lower surface of the reticle 6. Adjusted to position at position. In this way, the vertical position of the reticle 6 can be determined by the pin 7B.

  In the present embodiment, the elastic sheet 7F or the elastic foam sheet 7G is disposed between the pins 7B in the recess 10a. Similar to the elastic seal 7C, the elastic sheet 7F or the elastic foam sheet 7G closely adheres to the lower surface of the reticle 6 while being elastically deformed when the reticle 6 is clamped.

With the above configuration, as shown in FIG. 10B, the contact area with the reticle 6 is increased by the elastic sheet 7F or the elastic foam sheet 7G being elastically deformed during clamping. Even if foreign matter adheres to the elastic sheet 7F or the elastic foamed sheet 7G, the foreign matter is buried in these sheets, so that the holding force of the clamp on the reticle 6 can be increased. Further, since the elastic foam sheet 7G is an open cell body, the air layer on the contact surface with the reticle 6 surface is quickly released, the friction coefficient at the time of clamping is stabilized, and the clamp holding force (displacement direction) is increased. Can do. As the elastic foam sheet 7G, for example, a foam material or a porous material can be used.
[Fourth Embodiment]
FIG. 11 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred fourth embodiment of the present invention. The reticle clamp pad 7A of the present embodiment is generally the same as the reticle clamp pad 7A according to the first embodiment shown in FIG. However, it differs from the configuration of the first embodiment in that a foamed ceramic pin 7H is provided instead of the pin 7B of the first embodiment. Other configurations are substantially the same as those in the first embodiment, and thus the description thereof is omitted in the fourth embodiment.

FIG. 11 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred fourth embodiment of the present invention. In the first to third embodiments, the pin member 7B as the protrusion is made of the same material as the reticle clamp pad 7A. In the present embodiment, in order to quickly remove and release the air layer on the clamp contact surface of the reticle 6, the foamed ceramic pin 7H as a continuous porous body having continuous communication holes is used. As a result, the friction coefficient between the members can be stably compensated without causing a decrease in the friction coefficient due to the air layer on the surface of the clamp contact portion, so that the clamp holding force (displacement direction) can be increased. Become.
[Fifth Embodiment]
FIG. 12 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred fifth embodiment of the present invention. The reticle clamp pad 7A of the present embodiment is generally the same as the reticle clamp pad 7A according to the first embodiment shown in FIG. However, it differs from the configuration of the first embodiment in that a metal thin film layer 7J is used instead of the elastic seal 7C of the first embodiment. Other configurations are substantially the same as those in the first embodiment, and thus the description thereof is omitted in the fifth embodiment.

FIG. 12 is a conceptual diagram showing a configuration of a reticle clamp pad according to a preferred fifth embodiment of the present invention. In the first to fourth embodiments, the elastic seal 7C is used. However, in this embodiment, the reticle 6 and the pattern formed on the surface thereof are the same material depending on the surface treatment state of the lower surface clamp portion of the reticle 6. A metal thin film layer 7J such as chromium, nickel, or silicon can be used. At that time, it is possible to increase the clamp holding force (shift direction) by using the effect that the friction coefficient between the same materials is large. The metal thin film layer 7J is formed using, for example, a process such as metal plating, welding, or vapor deposition.
[Application example]
Next, a semiconductor device manufacturing process using this exposure apparatus will be described. FIG. 16 is a diagram showing a flow of an entire manufacturing process of a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask fabrication), a mask is fabricated based on the designed circuit pattern. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by using the above-described exposure apparatus and lithography technology using the above-described mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 5, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes the following steps. An oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, an electrode formation step for forming electrodes on the wafer by vapor deposition, an ion implantation step for implanting ions on the wafer, and applying a photosensitive agent to the wafer A resist processing step, an exposure step for transferring the circuit pattern to the wafer after the resist processing step by the above exposure apparatus, a development step for developing the wafer exposed in the exposure step, and an etching step for scraping off portions other than the resist image developed in the development step A resist stripping step that removes the resist that has become unnecessary after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

  In this way, by applying the exposure apparatus with improved alignment accuracy to the semiconductor device manufacturing process, it is possible to further increase the density and miniaturization of patterns of semiconductor integrated circuits and the like.

, , , , , 1 is a conceptual diagram showing a configuration of an exposure apparatus according to a preferred first embodiment of the present invention. , It is a conceptual diagram which shows the structure of the exposure apparatus which concerns on suitable 2nd Embodiment of this invention. , It is a conceptual diagram which shows the structure of the exposure apparatus which concerns on the suitable 3rd Embodiment of this invention. It is a conceptual diagram which shows the structure of the exposure apparatus which concerns on the suitable 4th Embodiment of this invention. It is a conceptual diagram which shows the structure of the exposure apparatus which concerns on the suitable 5th Embodiment of this invention. , , It is a conceptual diagram which shows the structure of the conventional exposure apparatus. It is a figure which shows the flow of the whole manufacturing process of a semiconductor device.

Explanation of symbols

1. Illumination system unit 2, reticle stage 3, reduction projection lens 4, wafer stage 4A, wafer 5, exposure apparatus main body 6, reticle 7, reticle clamp 7A, reticle clamp pad 7B, pin 7C, elastic seal 7D, elastic seal bracket 7E, elastic seal bracket joint surface (detachable surface)
7F, elastic sheet 7G, elastic foam sheet 7H, foam ceramic pin 7J, metal thin film layer slit exposure light 101, reticle 101A, slit exposure light 102, reticle stage 103, reticle clamp 103A, reticle clamp pad 103B, foreign matter 104, reduced projection Lens 105, wafer 106, wafer stage

Claims (14)

An exposure apparatus that projects and transfers a pattern drawn on an original to a substrate via a projection optical system,
An elastic member having a support surface for supporting the original plate or the substrate at the periphery thereof;
A support member for supporting the elastic member;
An exposure apparatus comprising: The support member is
A concave portion formed on the surface, and a plurality of protrusions disposed in the concave portion for supporting the original plate or the substrate,
The exposure apparatus according to claim 1, wherein the elastic member is disposed on an outer peripheral portion of the concave portion.   The exposure apparatus according to claim 1, further comprising an elastic sheet disposed in the recess.   The exposure apparatus according to claim 1, further comprising an elastic foam sheet disposed in the recess.   The exposure apparatus according to claim 1, wherein the elastic member is detachably disposed on the support member.   6. The exposure apparatus according to claim 5, wherein the elastic member is disposed on a bracket that is detachably disposed on the support member.   The exposure apparatus according to claim 2, wherein the protrusion includes a communicating porous body.   The exposure apparatus according to claim 7, wherein the communicating porous body includes a ceramic material.   The exposure apparatus according to claim 1, wherein the elastic member includes a fluorine-based resin or a polyparaxylene resin.   10. The elastic member according to claim 1, wherein an elastic coefficient in a direction perpendicular to the support surface is smaller than an elastic coefficient in a direction horizontal to the support surface. 11. Exposure device.   2. The support member or the elastic member is elastically supported so that an elastic coefficient in a direction perpendicular to the support surface is smaller than an elastic coefficient in a direction horizontal to the support surface. The exposure apparatus according to at least one of claims 9 to 9. A projection exposure apparatus for projecting and transferring a pattern drawn on an original to a substrate via a projection optical system, the metal thin film layer having a support surface for supporting the original or the substrate,
A support member for supporting the elastic member;
An exposure apparatus comprising:   The exposure apparatus according to claim 12, wherein the metal thin film layer includes chromium, nickel, and silicon. An application process for applying a photosensitive material to the substrate;
An exposure process of transferring a pattern using the exposure apparatus according to any one of claims 1 to 13, wherein the photosensitive material is applied in the application process.
A developing step of developing the photosensitive material of the substrate on which the pattern has been transferred in the exposure step;
A method for manufacturing a semiconductor device, comprising:

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