JP4227324B2 - Exposure equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure apparatus used in a manufacturing process of a device having a fine pattern such as a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, or the like.
[0002]
[Prior art]
8 and 9 show a conventional example of a projection exposure apparatus that projects and transfers a reticle pattern onto a silicon wafer in an exposure apparatus used in a semiconductor manufacturing process. FIG. 9 shows a more detailed configuration of the main part of the apparatus of FIG. In FIGS. 8 and 9, reference numeral 81 denotes a reticle serving as an original of an exposure pattern, 82 denotes a reticle stage on which the reticle 81 is mounted and scans the reticle with slit-shaped exposure light, and 83 denotes the reticle 81 to the reticle stage 82. It is a reticle clamp which is a means for clamping.
[0003]
84 is a reticle alignment scope for aligning the reticle 81 with a reticle alignment mark on the reticle stage 82, 85 is a reduction projection lens for reducing and projecting a pattern on the reticle 81 onto a wafer 86 made of a silicon substrate, and 87 is a wafer. 86 is a wafer stage that carries out scanning movement exposure with respect to the slit exposure light in synchronization with the reticle stage 82. Reference numeral 88 denotes an off-axis alignment scope for detecting a plurality of alignment marks on the wafer 81 and measuring pattern overlay accuracy on the wafer.
[0004]
In the above-described conventional configuration, the reticle 81 is clamped to the reticle clamp 83. Therefore, as shown in FIGS. 9 (1) and 9 (2), the reticle clamp pad 83A is configured in the reticle clamp 83, and the reticle clamp pad 83A. Is used as a vacuum pad, and the reticle 81 is clamped by a vacuum clamp 83 and a vacuum suction clamp. When the reticle 81 is clamped or exposed with the reticle, as shown in FIG. 9 (3), the reticle itself is projected on the wafer surface due to its own weight distortion, surface distortion and exposure thermal distortion. There has been a problem that the curvature of field of the pattern, the lateral displacement of the pattern, the distortion and the defocus in the pattern surface are deteriorated, and the pattern accuracy on the wafer is deteriorated.
[0005]
[Problems to be solved by the invention]
As shown in the above conventional example, in the conventional exposure apparatus, when the reticle is clamped and the pattern on the reticle surface is projected onto the wafer, the curvature of field is caused by the weight of the reticle itself, surface distortion, and exposure thermal distortion. Further, there has been a problem that pattern lateral deviation, distortion, and pattern in-plane defocus deteriorate, and the pattern accuracy on the wafer deteriorates. Similarly, when the wafer is clamped, the wafer flatness deteriorates due to the deterioration of wafer chuck flatness and exposure thermal distortion, and the curvature of field, pattern lateral deviation, distortion, and in-pattern defocus deteriorate, and There was a problem that the pattern accuracy deteriorated.
[0006]
An object of the present invention is to correct image distortion due to the flatness of at least one of a reticle (original) surface and a wafer (substrate) surface .
[0007]
[Means for Solving the Problems]
An exposure apparatus of the present invention that solves the above-described problems is an exposure apparatus that projects a pattern drawn on an original plate surface onto a substrate surface via a projection optical system, and exposes the substrate surface with an image of the pattern. Means for detecting the flatness of at least one of the original surface and the substrate surface; optical means for correcting distortion of the image provided between the original surface and the substrate surface; and four driving means a is, each of which tilt drive the pad and the hinge or 且 and a rotational bearing one said hinge or the pad which is supported on the rotary bearing for supporting the pad for holding the optical unit, four driving means and The four driving means are configured to correct distortion of the image on the substrate surface due to the flatness of at least one of the original surface and the substrate surface based on a signal from the means for detecting the flatness. Control And a means.
[0008]
Further, the exposure apparatus of the present invention comprises means for detecting displacement of the optical means, and the control means controls the four driving means by a detection signal of the means for detecting displacement.
Furthermore, the exposure apparatus of the present invention is characterized in that the means for detecting the flatness detects the flatness immediately before exposure.
Furthermore, the exposure apparatus of the present invention is characterized in that the optical means comprises a parallel glass substrate.
[0009]
Furthermore, the exposure apparatus of the present invention is characterized by having means for identifying the type of the original plate and selecting an optimum correction amount for each.
Furthermore, the exposure apparatus of the present invention is characterized in that the control by the control means is performed every time the original is exchanged, every time the substrate is exchanged, or every shot.
Further, the exposure apparatus of the present invention is a eight drive means, respectively to support the 且 one said hinge or the rotary bearing and a hinge or rotating bearings to support the pad and the pad for holding said optical means Further, the present invention is characterized by having eight driving means for tilting the pad.
[0010]
Furthermore, in the device manufacturing method of the present invention, the pattern drawn on the original plate surface is projected onto the substrate surface via the projection optical system using the exposure apparatus, and the substrate surface is exposed with an image of the pattern. It has a step.
[0011]
【Example】
Examples of the present invention will be described below.
[First embodiment]
FIG. 1 shows a schematic configuration of a step-and-scan type projection exposure apparatus (scanner) according to an embodiment of the present invention. FIG. 2 shows a more detailed configuration of the reticle stage portion in the exposure apparatus of FIG.
[0012]
In FIGS. 1 and 2, reference numeral 1 denotes a reticle, which is an original exposure pattern. 1A (FIG. 2) is an exposure slit that transmits slit-shaped exposure light, and 2 is a reticle stage that mounts the reticle 1 and scan-exposes the reticle 1 to the slit-shaped exposure light. 2A (FIG. 2) is a reticle alignment reference mark provided on the reticle stage 2, 3 is a reticle clamp which is means for clamping the reticle 1 to the reticle stage 2, and 3A (FIG. 2) is a reticle for vacuum-sucking the reticle 1. A reticle clamp pad 4 disposed on the clamp 3 is a reticle alignment scope for aligning the reticle 1 with a reticle alignment reference mark 2 A on the reticle stage 1. Reference numeral 5 denotes a reticle flatness detecting means which is provided at the pre-exposure movement position of the reticle 1 set near the exposure slit 1A above the reticle stage 2 and measures the flatness of the reticle.
[0013]
Reference numeral 6 denotes a reduction projection lens for reducing and projecting the pattern on the reticle 1 onto a wafer 7 made of a silicon substrate. Reference numeral 8 denotes a wafer 7 mounted thereon. In synchronization with the reticle stage 2, scanning movement exposure is performed with respect to the slit exposure light. A wafer stage 9 is an off-axis alignment scope that detects a plurality of alignment marks on the wafer 7 and measures the pattern overlay accuracy on the wafer 7.
[0014]
Reference numeral 10 denotes a mark detection means for detecting a mark detection signal when the reticle 1 is aligned with the reticle alignment reference mark 2A by the reticle alignment scope 4. Reference numeral 11 denotes an alignment mark alignment amount based on the mark detection signal of the mark detection means 10. An arithmetic processing circuit 12 is a drive control means for driving the reticle stage 2 in accordance with the alignment mark alignment amount calculated by the arithmetic processing circuit 11.
[0015]
Reference numeral 13 denotes a reticle flatness detection circuit for detecting the flatness of the reticle 1 based on a detection signal of the reticle flatness detection means 5, and reference numeral 14 denotes a reticle bend correction provided between the reticle 1 and the reduction projection lens 6. It is an optical system. The reticle bend correction optical system 14 is made of a parallel glass substrate, and is clamped and driven by the reticle bend correction optical system fine movement driving means 14A. Reference numeral 14B denotes a reticle bend correction optical system control circuit and fine movement driver, and reference numeral 14C denotes a reticle bend correction optical system displacement detection circuit that detects the displacement of the reticle bend correction optical system 14 by the correction optical system displacement sensor 15.
[0016]
In the above configuration, the reticle clamp pad 3A is configured on the reticle clamp 3, and the reticle 1 is clamped on the reticle clamp 3 by vacuum suction. At the time of clamping and exposure, the reticle 1 is deformed by its own weight, as shown in FIG. 3 (1) A, exposure thermal distortion deformation (broken line → solid line), as shown in FIG. 3 (2) A. , Exposure thermal distortion deformation (broken line → solid line), deformation reticle, reticle clamp deformation, exposure heat distortion deformation, etc. as shown in FIG.
[0017]
At this time, the flatness of the reticle 1 immediately before exposure is measured by the reticle flatness detection means 5 shown in FIG. 1, and the reticle flatness is measured by the reticle flatness detection circuit 13. Next, the reticle bend correction optical system control circuit and fine movement drive driver 14B converts the signal from the reticle flatness detection circuit 13 into a correction control drive signal, and reticle bend correction optical system fine movement drive means based on this correction control drive signal. 14A correctively drives the reticle bend correction optical system 14 so as to cancel the pattern distortion.
[0018]
FIGS. 3 (1) B, (2) B, and (3) B show how driving correction is performed by the reticle bend correction optical system fine movement driving means 14A. Here, in order to correct the pattern image from the deformed reticle 1, the reticle bend correction optical system 14 is displaced as shown in the figure by the reticle bend correction optical system fine movement driving means 14A, thereby correcting the pattern distortion. To do.
[0019]
FIG. 4 shows a configuration example of the reticle bend correction optical system fine movement driving means 14. In the example of FIG. 4A, a hinge 14E is provided below the clamp pad 14I that holds the reticle bend correction optical system (parallel glass substrate) 14, and the notch 14J for forming the hinge 14E has a PZT ( Piezoelectric elements) 14D are provided symmetrically with respect to the hinge 14E, and each PZT 14D is driven to extend and contract in the vertical direction, whereby the clamp pad 14I is tilt-driven and the reticle bend correction optical system 14 is displaced in the pattern correction direction.
[0020]
In another example of the fine movement driving means 14A, as shown in FIG. 4B, a notch 14J is provided on one side of the lower part of the clamp pad 14I holding the reticle bend correction optical system 14, and PZT ( Piezoelectric element) 14D is provided, and the reticle bend correction optical system 14 can be corrected and driven by driving the PZT 14D to extend and contract in the vertical direction. In still another example, as shown in FIG. 4 (3), a rotary bearing 14G is provided below the clamp pad 14I of the reticle bend correction optical system 14, and as shown in the figure below the center of rotation. The pressure bend spring 14H that pressurizes in the horizontal direction and the PZT (piezoelectric element) 14F that drives in the horizontal direction in the reverse direction are provided, and the reticle bend correction optical system 14 can be corrected and driven by the expansion and contraction drive of the PZT 14F. I can do it.
[0021]
[Second Embodiment]
As shown in FIGS. 5 (1) and 5 (2), as the reticle bend correction optical system fine movement driving means 14, in addition to the arrangement of the driving means shown in the first embodiment, it is concentric with the scanning direction or the exposure slit 1A. By arranging the driving means, it is possible to perform correction driving with higher accuracy.
[0022]
[Third embodiment]
As shown in FIG. 6, in addition to the modification of the quadratic curve approximation in the first embodiment, it is possible to perform tilt correction driving in the pattern offset correction direction as a matter of course even for a simple primary inclination of the reticle 1. .
[0023]
[Fourth embodiment]
As shown in FIG. 7, a wafer flatness detecting means 17 for detecting the flatness of the wafer 7 and a wafer flatness detecting circuit 16 are further provided, and a reticle bend correction optical system control circuit is provided by a signal from the wafer flatness detecting circuit 16. Alternatively, the fine bend driving driver 14B may send a drive signal to the reticle bend correction optical system fine move driving means 14A in a direction for correcting the pattern distortion on the wafer 7 to correct and drive the reticle bend correction optical system 14. Good. That is, the reticle bend correction optical system 14 can be driven to be corrected in a direction that cancels out the mutual distortion between the reticle 1 and the wafer 7. Of course, correction control using a detection signal of either the reticle flatness or the wafer flatness is also possible.
[0024]
As described above, according to the first to fourth embodiments, an exposure pattern distortion correction by the reticle bend correction optical system is performed to correct pattern lateral deviation and distortion at the time of exposure, and an accurate and stable mask. A projection image of a pattern is obtained, and exposure of a pattern with high resolution is enabled.
[0025]
<Example of semiconductor production system>
Next, an example of a production system for semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, etc.) will be described. In this method, maintenance services such as troubleshooting, periodic maintenance, and software provision for manufacturing equipment installed in a semiconductor manufacturing factory are performed using a computer network outside the manufacturing factory.
[0026]
FIG. 10 shows the whole system cut out from a certain angle. In the figure, reference numeral 101 denotes a business office of a vendor (apparatus supply manufacturer) that provides a semiconductor device manufacturing apparatus. As an example of a manufacturing apparatus, a semiconductor manufacturing apparatus for various processes used in a semiconductor manufacturing factory, for example, equipment for a pre-process (lithography apparatus such as an exposure apparatus, a resist processing apparatus, an etching apparatus, a heat treatment apparatus, a film forming apparatus, and a planarization Equipment) and post-process equipment (assembly equipment, inspection equipment, etc.). The office 101 includes a host management system 108 that provides a maintenance database for manufacturing apparatuses, a plurality of operation terminal computers 110, and a local area network (LAN) 109 that connects these to construct an intranet. The host management system 108 includes a gateway for connecting the LAN 109 to the Internet 105, which is an external network of the office, and a security function for restricting access from the outside.
[0027]
On the other hand, reference numerals 102 to 104 denote manufacturing factories of semiconductor device manufacturers as users of manufacturing apparatuses. The manufacturing factories 102 to 104 may be factories belonging to different manufacturers, or factories belonging to the same manufacturer (for example, a factory for a pre-process, a factory for a post-process, etc.). In each of the factories 102 to 104, a plurality of manufacturing apparatuses 106, a local area network (LAN) 111 that connects them together to construct an intranet, and host management as a monitoring apparatus that monitors the operating status of each manufacturing apparatus 106 are provided. A system 107 is provided. The host management system 107 provided in each factory 102 to 104 includes a gateway for connecting the LAN 111 in each factory to the Internet 105 which is an external network of the factory. As a result, the host management system 108 on the vendor 101 side can be accessed from the LAN 111 of each factory via the Internet 105, and only a limited user is permitted to access by the security function of the host management system 108. Specifically, status information (for example, a symptom of a manufacturing apparatus in which a trouble has occurred) indicating the operating status of each manufacturing apparatus 106 is notified from the factory side to the vendor side via the Internet 105, and the notification is also handled. It is possible to receive response information (for example, information for instructing a coping method for trouble, coping software or data), maintenance information such as the latest software and help information from the vendor side. A communication protocol (TCP / IP) generally used on the Internet is used for data communication between the factories 102 to 104 and the vendor 101 and data communication on the LAN 111 in each factory. Instead of using the Internet as an external network outside the factory, it is also possible to use a high-security dedicated line network (such as ISDN) without being accessible from a third party. Further, the host management system is not limited to the one provided by the vendor, and the user may construct a database and place it on the external network, and allow access to the database from a plurality of factories of the user.
[0028]
FIG. 11 is a conceptual diagram showing the overall system of this embodiment cut out from an angle different from that in FIG. In the previous example, a plurality of user factories each equipped with a manufacturing apparatus and a management system of a vendor of the manufacturing apparatus are connected via an external network, and production management of each factory or at least one unit is performed via the external network. Data communication of manufacturing equipment was performed. On the other hand, in this example, a factory equipped with a plurality of vendors' manufacturing devices and a management system of each vendor of the plurality of manufacturing devices are connected by an external network outside the factory, and maintenance information of each manufacturing device is obtained. Data communication. In the figure, reference numeral 201 denotes a manufacturing factory of a manufacturing apparatus user (semiconductor device manufacturer), and a manufacturing apparatus for performing various processes on the manufacturing line of the factory, in this example, an exposure apparatus 202, a resist processing apparatus 203, and a film forming processing apparatus 204. Has been introduced. In FIG. 11, only one manufacturing factory 201 is depicted, but actually, a plurality of factories are similarly networked. Each device in the factory is connected by a LAN 206 to form an intranet, and the host management system 205 manages the operation of the production line. On the other hand, vendors (apparatus supply manufacturers) such as exposure apparatus manufacturer 210, resist processing apparatus manufacturer 220, and film formation apparatus manufacturer 230 have host management systems 211, 221 for remote maintenance of the supplied devices. 231 and these comprise a maintenance database and an external network gateway as described above. The host management system 205 that manages each device in the user's manufacturing factory and the vendor management systems 211, 221, and 231 of each device are connected by the external network 200, which is the Internet or a dedicated line network. In this system, if a trouble occurs in any one of a series of production equipment on the production line, the operation of the production line is suspended, but remote maintenance via the Internet 200 is received from the vendor of the troubled equipment. This enables quick response and minimizes production line outages.
[0029]
Each manufacturing apparatus installed in the semiconductor manufacturing factory includes a display, a network interface, a computer for executing network access software stored in a storage device and software for operating the apparatus. The storage device is a built-in memory, a hard disk, or a network file server. The network access software includes a dedicated or general-purpose web browser, and provides, for example, a user interface having a screen as shown in FIG. 12 on the display. The operator who manages the manufacturing apparatus in each factory refers to the screen while referring to the screen of the manufacturing apparatus (401), serial number (402), trouble subject (403), date of occurrence (404), urgency (405), Information such as symptom (406), coping method (407), progress (408), etc. is input to the input items on the screen. The input information is transmitted to the maintenance database via the Internet, and appropriate maintenance information as a result is returned from the maintenance database and presented on the display. The user interface provided by the web browser further realizes a hyperlink function (410 to 412) as shown in the figure, and the operator can access more detailed information on each item or use the software library provided by the vendor for the manufacturing apparatus. The latest version of software can be pulled out, and operation guides (help information) can be pulled out for reference by factory operators.
[0030]
Next, a semiconductor device manufacturing process using the production system described above will be described. FIG. 13 shows the flow of the entire manufacturing process of the semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. 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 lithography using the prepared 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 4, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7). The pre-process and post-process are performed in separate dedicated factories, and maintenance is performed for each of these factories by the remote maintenance system described above. In addition, information for production management and apparatus maintenance is communicated between the pre-process factory and the post-process factory via the Internet or a dedicated network.
[0031]
FIG. 14 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed onto the wafer by exposure using the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. Since the manufacturing equipment used in each process is maintained by the remote maintenance system described above, it is possible to prevent problems before they occur, and to recover quickly if a problem occurs. Productivity can be improved.
[0032]
【The invention's effect】
As described above, according to the present invention, it is possible to correct image distortion due to flatness of at least one of a reticle (original) surface and a wafer (substrate) surface .
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a projection exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a more detailed configuration diagram of a reticle stage portion in the apparatus of FIG. 1;
FIG. 3 is a diagram for explaining various reticle deformations and correction methods thereof in the apparatus of FIG. 1;
4 is a diagram showing a configuration of correction optical system fine movement driving means in the apparatus of FIG. 1; FIG.
FIG. 5 is a diagram showing another configuration example of the correction optical system fine movement driving unit in the apparatus of FIG. 1;
6 is a diagram for explaining another example of a deformed state of the reticle in the apparatus of FIG. 1 and a correction method thereof. FIG.
FIG. 7 is a conceptual diagram showing a configuration of a projection exposure apparatus according to a fourth embodiment of the present invention.
FIG. 8 is a conceptual diagram showing a configuration of a conventional projection exposure apparatus.
9 is a more detailed configuration diagram of a reticle stage portion in the apparatus of FIG. 8. FIG.
FIG. 10 is a conceptual diagram of a semiconductor device production system viewed from a certain angle.
FIG. 11 is a conceptual diagram of a semiconductor device production system viewed from another angle.
FIG. 12 is a specific example of a user interface.
FIG. 13 is a diagram illustrating a flow of a device manufacturing process.
FIG. 14 is a diagram illustrating a wafer process.
[Explanation of symbols]
1: reticle, 1A: exposure slit (or slit exposure light), 2: reticle stage, 2A: reticle alignment reference mark, 3: reticle clamp, 3A: reticle clamp pad, 4: reticle alignment scope, 5: reticle flatness detection Means: 6: reduction projection lens, 7: wafer, 8: wafer stage, 9: off-axis alignment scope, 10: mark detection means, 11: arithmetic processing circuit 12: drive control means, 12: reticle flatness detection circuit, 14 : Reticle bend correction optical system, 14A: Reticle bend correction optical system fine movement drive means, 14B: Reticle bend correction optical system control circuit and fine movement drive driver, 14C: Reticle bend correction optical system displacement detection means, 14D: PZT (piezoelectric element) , 14E: hinge, 14F: PZT (piezoelectric element ), 14G: Rotating bearing, 14H: Pressure spring, 14I: Reticle bend correction optical system clamp pad, 14J: Notch, 15: Correction optical system displacement sensor, 16: Wafer flatness detection means, 17: Wafer flatness Detection circuit, 81: reticle, 82: reticle stage: 82A: reticle alignment reference mark, 83: reticle clamp, 83A: reticle clamp pad, 84: reticle alignment scope, 85: reduction projection lens, 86: wafer, 87: wafer stage 88: Off-axis alignment scope.

Claims (8)

In an exposure apparatus that projects a pattern drawn on an original surface onto a substrate surface via a projection optical system and exposes the substrate surface with an image of the pattern.
Means for detecting the flatness of at least one of the original surface and the substrate surface;
Optical means for correcting distortion of the image provided between the original surface and the substrate surface;
A four drive means, each of which tilt drive pad and hinge or one 且 and a rotational bearing the hinge or the pad which is supported on the rotary bearing for supporting the pad for holding the optical unit, 4 Two drive means,
Based on the signal from the means for detecting the flatness, the four driving means are controlled so as to correct distortion of the image on the substrate surface due to the flatness of at least one of the original surface and the substrate surface. And an exposure apparatus.   2. The exposure apparatus according to claim 1, further comprising means for detecting a displacement of the optical means, wherein the control means controls the four driving means by a detection signal of the means for detecting the displacement.   The exposure apparatus according to claim 1, wherein the flatness detecting unit detects the flatness immediately before exposure.   The exposure apparatus according to claim 1, wherein the optical unit includes a parallel glass substrate.   5. The exposure apparatus according to claim 1, further comprising means for identifying the type of the original plate and selecting an optimum correction amount for each.   6. The exposure apparatus according to claim 1, wherein the control by the control unit is performed every time the original is exchanged, every substrate is exchanged, or every shot. A eight driving means, each of which tilt drive pad and hinge or one 且 and a rotational bearing the hinge or the pad supported on the rotary bearing for supporting the pad for holding the optical unit, 8 The exposure apparatus according to claim 1, further comprising one driving unit.   Using the exposure apparatus according to any one of claims 1 to 7, a pattern drawn on an original plate is projected onto a substrate surface via a projection optical system, and the substrate surface is exposed with an image of the pattern A device manufacturing method comprising the step of:

Images