JP2006222198A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for properly suppressing the influence of exposure atmosphere contamination and which is used for the manufacture of a device including fine patterns, such as semiconductor devices or the like. <P>SOLUTION: The aligner comprises a light source 17 for emitting a pulsed light, a lighting optical system 18 for collecting the light from this light source 17 to light an original pattern, such as a reticle 12, a projection optical system 19 for guiding the light from the original pattern to a wafer 22 as the exposure object, a wafer stage 21 for placing the exposure object, a rotating body 54 having at least one blade 51 within the space where the light passes, and a cooling means 41. The rotating body 54 makes the blade 51 rotate, in synchronization with the pulse timing of the light source 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for suppressing the influence of exposure atmosphere contamination, which is suitable for manufacturing a device having a fine pattern such as a semiconductor device.

  In particular, the present invention is an exposure apparatus that performs exposure using light having a short wavelength (0.5 to 50 nm) such as EUV light, or exposure using an optical element such as a mirror or a lens in a high vacuum atmosphere. It is suitable for an exposure apparatus that performs the above.

  In recent years, in the photolithography technology for manufacturing semiconductors, the exposure light used has been shortened in wavelength, and has evolved from i-line and g-line to KrF excimer laser light and ArF excimer laser light. If the wavelength of the exposure light is shortened, a finer mask pattern can be transferred to the wafer. However, in order to expose a pattern with a narrow line width, there is a theoretical limit in lithography using ultraviolet light. Therefore, EUV lithography using extreme ultraviolet light (EUV light, 13 to 20 nm) having a shorter wavelength than ultraviolet light has attracted attention.

  Since a typical wavelength used in EUV light is 13.5 nm, it is possible to realize a resolution far higher than that of conventional optical lithography, but on the other hand, it is easily absorbed by substances. For this reason, when performing reduced exposure using a refractive optical system, as in conventional lithography using ultraviolet light as a light source, EUV light is absorbed by the glass material, and the amount of light that reaches an object to be exposed such as a wafer Will become extremely small. For this reason, when performing exposure using EUV light, it is necessary to configure reduced exposure using a reflective optical system.

  FIG. 9 shows a schematic view of a conventional reduction projection exposure apparatus using EUV light (see Patent Document 1). The EUV exposure apparatus 200 includes an EUV light source 210, an illumination optical system 220, a reticle (mask) 230, an alignment optical system 240, a reticle stage 250, a wafer stage 260, a wafer 270, a vacuum container 280, a reflective reduction projection optical system 100, a first one. 1 mirror 110, second mirror 120, third mirror 130, fourth mirror 140, fifth mirror 150, and sixth mirror 160, and exhausts the gas in the vacuum vessel 280. An exhaust system (not shown) is also provided.

  There are several types of EUV light sources, and one of them, a laser-produced plasma light source, can emit light only in a necessary wavelength band by selecting a target material. For example, when Xe is ejected from a pulse nozzle as a target material and plasma is generated by irradiating it with a pulse laser, EUV light having a wavelength of 13 to 14 nm is emitted.

In order to avoid absorption of EUV light by a substance, the EUV exposure apparatus needs to keep a space where the EUV light is irradiated in a vacuum. Therefore, a plurality of exhaust systems such as vacuum pumps are attached to the exposure apparatus.
JP 2003-45782 A

EUV light used in the EUV exposure apparatus is absorbed by the atmosphere in the apparatus. In particular, oxygen and moisture strongly absorb EUV light. Therefore, in order to keep the EUV light transmittance high, it is necessary to use a vacuum pump or the like to evacuate the chamber. In the chamber through which EUV light passes, it is desirable that the pressure is 10 ⁻³ Pa or less and the partial pressures of oxygen and moisture are extremely low. However, moisture and the like that have adhered to the wafer diffuse in the chamber as the wafer is transported. Furthermore, moisture tends to adhere to the inner wall of the chamber and is difficult to exhaust. When moisture adheres to the optical element, it oxidizes the optical element and becomes one of the causes of reducing the reflectance of the optical element.

  Further, when the chamber is in a vacuum state, hydrocarbons are generated from a mechanism such as a stage. Furthermore, during the exposure, the reaction of the exposure light with the resist also generates hydrocarbons. When these hydrocarbons are exposed to the exposure light on the optical element surface, they adhere to the optical element surface as carbon. Carbon adhering to the optical element absorbs EUV light and reduces the reflectivity of the optical element. Decreasing the reflectance of the optical element leads to a decrease in throughput.

  From the above, it is necessary to keep the partial pressure of moisture and hydrocarbon particularly low in the space where the optical element in the EUV exposure apparatus is installed.

  In order to reduce the partial pressure of moisture, hydrocarbons, etc. in the exposure apparatus, measures to increase the capacity of the exhaust system such as a vacuum pump are also effective. However, it is difficult to improve the throughput because moisture adhering to the transferred wafer and hydrocarbons generated from the resist and stage mechanism are not allowed to drift into the space where the optical element is installed due to diffusion.

  Also, in an EUV exposure apparatus, particles may be generated by sliding or friction, such as operation of a robot hand or gate valve, before the reticle or wafer is transferred to the apparatus chamber, and this may adhere to the reticle or wafer. is there. Furthermore, particles generated from a movable part such as a stage may adhere to the surface of the reticle or wafer during exposure.

  Thus, when particles adhere to the surface of a reticle or wafer, there is a problem that the yield of device manufacturing and the reliability of devices are lowered. In particular, when particles adhere to the circuit pattern surface of the reticle, in actual exposure, the particles are transferred to the exact same position for each shot. For this reason, there is a problem that the yield of device manufacturing and the reliability of the device are greatly reduced.

  An object of the present invention is to solve or suppress at least one problem in the above-described conventional example.

The present invention for achieving the above object may be any of the following (1) to (12).
(1) An exposure apparatus for exposing a pattern to a substrate, comprising: a rotating body having blades in a space through which exposure light passes.
(2) The exposure apparatus according to (1), wherein a cooling unit is provided in a space including the rotating body.
(3) The exposure apparatus according to (2), further comprising a plate connected to the cooling means.
(4) The above described (2) or (3), comprising: the rotating body; and a container that includes the cooling means and includes an opening and an exhaust for allowing the pulsed light from the light source to pass therethrough. Exposure equipment.
(5) The exposure apparatus according to (4), wherein the container includes an open / close door that shields the opening.
(6) The exposure apparatus according to any one of (2) to (5), wherein the blade is radiatively cooled by the cooling means.
(7) The exposure apparatus according to any one of (1) to (6), wherein the rotating body rotates the blades in synchronization with the pulse timing of the light source without blocking the pulsed light.
(8) An illumination optical system and a projection optical system for exposing the pattern to the substrate, and means for controlling the temperature of a vacuum chamber containing at least one of the two optical systems. The exposure apparatus according to any one of (2) to (7) above.
(9) The exposure apparatus according to any one of (1) to (8) above, wherein the exposure apparatus has a porous structure in a space containing either the rotating body or the cooling unit.
(10) The exposure apparatus according to any one of (1) to (9), wherein the motor that rotates the rotating body includes a bearing.
(11) An original stage having the original plate having the pattern and a substrate stage having the substrate mounted thereon, wherein the rotating body is disposed between the original stage and the substrate stage. The exposure apparatus according to any one of (1) to (10) above.
(12) A device manufacturing comprising: exposing the substrate using the exposure apparatus according to any one of (1) to (11); and developing the exposed substrate. Method.
Also, the present invention provides, for example, a light source that emits pulsed light, an illumination optical system that condenses light from the light source and illuminates the original, and a projection optical system that guides light from the original to an object to be exposed. A stage on which the object to be exposed is placed, a rotating body having at least one blade in a space through which light passes, and a cooling means, wherein the rotating body is synchronized with the pulse timing of the light source. An exposure apparatus that rotates blades.

  Other features of the invention and corresponding objects and advantages will become apparent from the following description made with reference to the accompanying drawings. In the drawings, the same or similar reference numerals represent the same or similar components throughout the drawings.

  According to the present invention, a technique for suppressing the influence of exposure atmosphere contamination, which is suitable for manufacturing a device having a fine pattern such as a semiconductor device, in particular, an EUV exposure apparatus or an optical element under a high vacuum atmosphere. It is possible to provide the technique suitable for an exposure apparatus that uses the exposure.

  Hereinafter, as a preferred form of the exposure apparatus according to the present invention, an embodiment in which the original plate is a reticle and the substrate is a wafer will be described in detail with reference to the accompanying drawings.

1 and 2 show an embodiment 1 of an exposure apparatus using the EUV light of the present invention (here, light having a wavelength of 0.1 to 30 nm, more preferably 10 to 15 nm).
The exposure apparatus includes a light source 17, an illumination optical system 18, a projection optical system 19, a reticle illumination mirror 1, a reticle holding unit 15 that holds a reticle 12, a reticle stage 11 that carries the reticle holding unit 15, and a wafer that holds a wafer 22. It has a holding unit 24, a wafer stage 21 on which the wafer holding unit 24 is mounted, a reticle alignment optical system 16, a wafer alignment optical system 25, and a focus position detection mechanism 26.
The EUV light 8 emitted from the light source 17 is irradiated onto the reticle 12 via the illumination optical system 18 and the reticle illumination mirror 1 and reflected. The reflected EUV light is applied to the wafer 22 via the projection optical system 19.

  There are several types of light sources 17, and one of them, the laser-produced plasma light source, can emit light only in a necessary wavelength band by selecting a target material. For example, when Xe is ejected from a pulse nozzle as a target material and plasma is generated by irradiating it with a pulse laser, EUV light having a wavelength of 13 to 14 nm is emitted.

  The illumination optical system 18 includes a plurality of multilayer mirrors and an optical integrator. The role of the illumination optical system 18 includes efficiently condensing the light emitted from the light source, and making the illuminance of the exposure area uniform. The optical integrator has a role of uniformly illuminating the mask with a predetermined numerical aperture.

  The projection optical system 19 includes mirrors 2 to 7. Each of the mirrors 2 to 7 is a multilayer mirror in which Mo and Si are alternately coated. Since this multilayer film has a direct incidence reflectance of EUV light of about 67%, most of the energy absorbed by the multilayer mirror is changed to heat. Therefore, low thermal expansion glass or the like is used as the mirror base material.

  The reticle stage 11 and the wafer stage 21 have a mechanism that is driven in a vacuum environment, and perform scanning in synchronization with a speed ratio proportional to the reduction magnification. The positions and postures of the reticle stage 11 and the wafer stage 21 are observed and controlled by a laser interferometer (not shown). The reticle stage 11 and the wafer stage 21 have fine movement mechanisms, respectively, and can position the reticle 12 or the wafer 22.

  The alignment detection mechanism includes a reticle alignment optical system 16 and a wafer alignment optical system 25. The optical system 16 and the optical system 17 each have a positional relationship between the position of the reticle 12 and the optical axis of the projection optical system 19. The positional relationship between the wafer 22 and the optical axis of the projection optical system 19 is measured. Based on the result, the positions and angles of the reticle stage 11 and the wafer stage 21 are adjusted so that the projected image of the reticle 12 matches a predetermined position on the wafer 22.

The focus position detection mechanism 26 detects a vertical focus position on the wafer surface in order to keep the imaging position of the projection optical system 19 on the wafer surface.
When one exposure is completed, the wafer stage 21 moves stepwise in the X and Y directions, moves to the next scanning exposure start position, and performs exposure again.

  In the EUV exposure apparatus, as described above, the irradiated EUV light reacts with the resist coated on the wafer surface to generate an organic gas, and the organic gas reacts with the EUV light again on the mirror surface of the projection optical system. Then, it has a problem of adhering to the surface of the mirror as carbon.

In this embodiment, an exposure apparatus is provided that prevents the organic gas generated from the resist from adhering to the surface of the mirror as much as possible and prevents the exposure performance and throughput from being lowered.
In this embodiment, the rotating body 54 having blades is arranged between the mirror 6 and the mirror 7 and the blades 51 pass directly above the stage space opening 91. Although the number of blades 51 of the rotating body 54 described in the present embodiment is four, the number of blades and the blade shape are not limited to this.

  Here, the space between the mirror 6 and the mirror 7 through which the optical axis of the EUV light passes is referred to as an EUV light passage space (not shown). The rotating body 54 having the blades 51 synchronizes with the pulse timing of the light source. When the EUV light 8 is irradiated, the blades 51 do not cross the EUV light passage space and the EUV light 8 is not irradiated. The motor 55 is controlled by the sensor R1 and the rotation controller 27 so as to cross the EUV light passage space.

  For example, since the EUV light 8 repeats irradiation and non-irradiation in a pulsed manner, in the case of the rotating body 54 having four blades 51, the blades 51 block the EUV light 8 by rotating at least 1/4 at the time of non-irradiation. It is possible to rotate without.

  Since the aforementioned outgas molecules are in a vacuum environment, they pass through the stage space opening 91 and enter the projection optical system space 10. As shown in FIG. 6, the trajectory of the outgas molecules that have entered is forcibly changed by the blades 51 of the rotating body 54, and travels toward the cryopanel 45. Since the cryopanel 45 is cooled to about 100K or less by the refrigerator 42, outgas molecules colliding with the panel surface adhere to the panel surface. As described above, since most of the outgas molecules that pass through the stage space opening 91 and enter the projection optical system space 10 are captured by the blades 51 and the cryopanel 45, adhesion of the outgas molecules to the mirror surface is reduced. It is possible.

  In order to maintain the performance of the cryopanel 45, a regeneration process for periodically releasing gas molecules adhered to the panel surface is necessary. In that case, by closing the open / close door 71 that spatially separates the space in which the cryopanel 45 is installed and the projection optical system space 10, gas molecules released from the panel surface float in the projection optical system space 10. To prevent that. The released gas molecules are exhausted to the outside by the turbo molecular pump 36.

  Further, since the cryopanel 45 radiatively cools the main body chamber 9 and the projection system mirror 6 around the cryopanel 45, it is necessary to have a configuration in which each is kept at a constant temperature. The main body chamber 9 is configured to be maintained at a constant temperature by the heater 65 and the temperature controller 28, and a radiation shield (not shown) that reduces the influence of radiation cooling is provided between the cryopanel 45 and the main body chamber 9. I do not care. The mirror 6 and the mirror 7 are configured such that the mirror is covered with radiation shields 66 and 67 so that the irradiation surface of the EUV light 8 is not blocked, and heaters 63 and 64 are provided.

  Further, the cryopanel 46 disposed so as to surround the blades 51 radiates and cools the blades 51 and allows the blades 51 themselves to function as a cryopanel, thereby more reliably capturing outgas molecules.

  Further, since the cryopanel 46 is cooled by the refrigerator 41 and the main chamber 9 is also radiatively cooled, the temperature of the main chamber 9 is controlled by the heaters 61 and 62 and the temperature controller 28.

  Moreover, it is preferable to provide a magnetic bearing in the rotating part of the motor 55. By using a magnetic bearing, particles generated from the bearing portion can be reduced.

  3 to 5 show an exposure apparatus, a rotating body, and a container containing the exposure apparatus according to the second embodiment of the present invention. In the first embodiment, the rotating body 54 having the blades 51 is disposed at one location between the mirror 6 and the mirror 7. However, in this embodiment, near the surface of the mirror 6, near the surface of the mirror 7, and the wafer 22. FIG. 3 shows an example of arrangement at three locations in the vicinity of the surface.

  4 and 5 are detailed views of the rotating body 54 having the blades 51. FIG. The blades 51 and the rotating body 54 are included in the blade cover 92, and a part of the cryopanel 45 is disposed between the blade cover 92 and the blades 51. The blade cover 92 is provided with minimum openings 81 and 82 that do not block the EUV light 8, and the openings 81 and 82 are provided with opening and closing doors 71 and 72, respectively, to separate the space in the blade cover 92 from the outside. It is possible. Here, the opening sizes of the openings 81 and 82 of the blade cover 92 differ depending on the positions where they are arranged. The blade cover 92 includes a heater 61 and a turbo molecular pump 34. The rotating body 54 is driven by the motor 55 and the controller 27, and the driving method is the same as in the previous invention.

  First, the rotating body 54 having the blades 51 arranged on the wafer 22 is caused by collision of the outgas molecules generated from the resist through the opening 82 of the blade cover 92 toward the projection optical system space 10 with the blades 51. Forcibly change in the direction of the cryopanel 45 provided near the blades 51. Outgas molecules that collide with the cryopanel 45 are adhered to the panel surface.

  Further, the blade 51 may be radiatively cooled by the cryopanel 45 installed in the blade cover 92 so that the blade 51 itself functions as a cryopanel. When the blades 51 function as a cryopanel, the outgas molecules colliding with the blades 51 are directly adhered, so that the recovery efficiency of the outgas molecules can be increased.

  Further, the inside of the blade cover 92 and the blade 51 may be coated with a porous material such as powdered activated carbon. When recovering hydrogen molecules and the like floating in the projection optical system space 10 and increasing the degree of vacuum in the space, it is difficult to recover the hydrogen molecules and the like with the cryopanel 45, but the floating hydrogen molecules and the like are adsorbed by the porous material. It becomes possible to collect by using.

  Further, when the blade cover 92 is radiatively cooled by the cryopanel 45, the heater 61 and the temperature controller 28 can keep the temperature constant. Further, a configuration in which a cooling device (not shown) is arranged in the motor 55 to suppress heat generation of the motor 55 is preferable.

  During the regeneration process of the cryopanel 45, by closing the open / close doors 71 and 72 of the openings 81 and 82 of the blade cover 92, gas molecules released from the panel surface are prevented from flowing out into the projection optical system space 10, and the blade The released gas is exhausted to the outside by the turbo molecular pump 34 provided in the cover 92. Further, an inert gas is supplied into the projection optical system space 10 from a gas supply port (not shown), and the pressure in the projection optical system space 10 is maintained at a positive pressure from the pressure in the blade cover 92. The emitted gas and the inert gas may be exhausted to the outside by the turbo molecular pump 34 provided. In this case, the opening / closing doors 71 and 72 of the openings 81 and 82 of the blade cover 92 are not necessary, and the structure of the blade cover 92 can be simplified.

  The rotating body 58 having the blades 52 installed on the surface of the mirror 6 prevents the outgas molecules that have entered the projection optical system space 10 from colliding with the surface of the mirror 6, and the blades 53 installed on the surface of the mirror 7. The rotator 59 having the function of preventing the outgas molecules that have entered the projection optical system space 10 from colliding with the surface of the mirror 7.

  In the present embodiment, the number of blades of the rotating bodies 54, 58, 59 is four, but the number of blades and the blade shape are not limited to this. Similarly, a rotating body 54 having blades 51 may be provided on the surfaces of the other mirrors 2 to 5 and the surface of the reticle 12. By installing the rotating body 54 having the blades 51 on the other mirrors and the reticle 12, it is possible to prevent the outgas molecules from adhering to the surfaces of the mirrors and the reticle and maintain the performance of the exposure apparatus. Become.

  Next, as a third embodiment of the present invention, a semiconductor device manufacturing process using the exposure apparatus according to the first or second embodiment will be described. FIG. 7 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 production), a mask is produced 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 4, 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 has the following steps (FIG. 8). 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.

1 is a diagram schematically showing a configuration of Example 1 of the present invention. FIG. It is a figure which shows 1 part of a structure of Example 1 of this invention. It is a figure which shows roughly the structure of Example 2 of this invention. It is sectional drawing of the container which includes the rotary body which has the blade | wing of Example 2 of this invention. It is a top view of the container which includes the rotary body which has the blade | wing of Example 2 of this invention. It is a figure which the blade | wing of Example 1 of this invention changes a molecular orbital. It is a figure showing the semiconductor manufacturing process which concerns on Example 3 of this invention. It is a figure showing a wafer process. It is the schematic of the conventional EUV exposure apparatus.

Explanation of symbols

  1: reticle illumination mirror, 2-7: projection system first to sixth mirrors, 8: EUV light, 9: body chamber, 10: projection optical system space, 11: reticle stage, 12: reticle, 13: reticle exchange door, 14: reticle parts, 15: reticle holding unit, 16: reticle alignment optical system, 17: light source, 18: illumination optical system, 19: projection optical system, 21: wafer stage, 22: wafer, 23: wafer exchange door, 24 : Wafer holder, 25: Wafer alignment optical system, 26: Focus position detection mechanism, 27: Controller, 26: Temperature controller, 31-37: Turbo molecular pump, 41, 42: Refrigerator, 45-47: Cryo Panels 51-53: Blades 54, 58, 59: Rotating bodies 55-57: Motors 61-65: Heaters 66, 67: Radiation shields 71, 72: Closing, 81, 82: opening, 91: stage space opening, 92: blade cover, S1 to S4: the pressure sensor, R1: rotation sensor.

Claims (12)

In an exposure apparatus that exposes a pattern onto a substrate,
An exposure apparatus comprising a rotating body having blades in a space through which exposure light passes.   The exposure apparatus according to claim 1, further comprising a cooling unit in a space containing the rotating body.   The exposure apparatus according to claim 2, further comprising a plate connected to the cooling unit.   4. The exposure apparatus according to claim 2, comprising: the rotating body; and a container that includes the cooling unit and includes an opening and an exhaust for allowing the pulsed light from the light source to pass therethrough.   The exposure apparatus according to claim 4, wherein the container includes an opening / closing door that shields the opening.   6. The exposure apparatus according to claim 2, wherein the blade is radiatively cooled by the cooling means.   The exposure apparatus according to claim 1, wherein the rotating body rotates the blade in synchronization with the pulse timing of the light source without blocking the pulsed light.   2. An illumination optical system and a projection optical system for exposing the pattern to the substrate, and means for temperature-controlling a vacuum chamber containing at least one of the two optical systems. The exposure apparatus according to any one of 2 to 7.   The exposure apparatus according to claim 1, wherein the exposure apparatus has a porous structure in a space containing either the rotating body or the cooling unit.   The exposure apparatus according to claim 1, wherein the motor that rotates the rotating body includes a bearing.   2. An original plate stage on which an original plate having the pattern is mounted and a substrate stage on which the substrate is mounted, and the rotating body is disposed between the original plate stage and the substrate stage. Item 11. The exposure apparatus according to any one of Items 1 to 10. 12. A device manufacturing method comprising: exposing the substrate using the exposure apparatus according to claim 1; and developing the exposed substrate.

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