JP2005072404A - Aligner and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize high precision exposure by preventing the contamination of a lens due to liquid in a liquid immersion aligner. <P>SOLUTION: In the aligner 1 for performing exposure in a state where liquid L is filled between a light exit end 2a of an optical lens 2 and a wafer W as an exposure object; there are provided, below the light exit end 2a freely to go forward and backward, a cleaning nozzle 10 for injecting a cleaning solution LC toward the light exit end 2a of the optical lens 2, a gas nozzle 11 for injecting gas toward the light exit end 2a, and a brush 12 for removing the contamination of the light exit end 2a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an immersion type exposure apparatus that performs exposure in a state where a liquid is interposed between a light emitting end of an optical lens portion and an exposure area on a substrate, and a method of manufacturing a semiconductor device using the exposure.

  The immersion type exposure apparatus has been studied for practical use as a technique for improving the resolution limit and depth of focus of the semiconductor exposure apparatus. Specifically, the exposure is performed by filling a liquid between the lens and the object to be exposed, which is normally filled with air (refractive index: n = 1), with a liquid tank or the like. In general, the refractive index of a liquid is larger than 1, and the wavelength is substantially shorter than in air, so that the resolution limit and the depth of focus are improved (see, for example, Patent Documents 1 and 2).

  Conventionally, when applying this technique, which has been applied as a technique for improving the resolution of a microscope, to an exposure apparatus, exposure is performed by filling an exposure target such as a wafer and a stage and a lens on which the wafer is placed with a liquid. In the case of mass production, it is necessary to replace and expose the wafer at a level of several tens to hundreds of sheets per hour, and at the time of replacement, the liquid needs to be discharged and filled again.

JP-A-10-303114 International Publication No. 99/49504 Pamphlet

  However, if a wafer coated with resist through various processing steps is immersed in a liquid, the deposits may be dissolved in the liquid, and the contaminated liquid attached to the lens when the liquid is discharged may contaminate the lens. Here, it is not a big problem when the exposure is performed one after another and the liquid is changed frequently, but when the waiting time is long, the liquid dries, and contaminants adhere to the lens and hinder the exposure. The problem of becoming.

  The present invention has been made to solve such problems. That is, the present invention provides an exposure apparatus that performs exposure in a state where a liquid is filled between the light exit end of the optical lens unit and the substrate to be exposed, and the cleaning liquid is applied toward the light exit end of the optical lens unit. A jet nozzle is provided in the lower part of the light exit end so as to be able to advance and retreat. Further, in the method of manufacturing a semiconductor device including a step of performing exposure in a state where a liquid is filled between the light emitting end of the optical lens unit and the substrate to be exposed, after the exposure, In this method, a cleaning liquid is jetted toward the light exit end to perform a process of cleaning the light exit end of the optical lens unit.

  According to the present invention, in the immersion type exposure apparatus and exposure method, even when contaminants adhere through the liquid when the light exit end of the optical lens unit touches the liquid, the cleaning liquid is surely ejected. Can be removed. That is, at a predetermined timing after exposure, the cleaning nozzle extends below the light emitting end, and the liquid is ejected to the light emitting end. Thereby, the contaminants adhering to the surface of the light emitting end can be removed. Further, before the exposure, the cleaning nozzle can be moved away from the lower side of the light emitting end so as not to interfere with the exposure.

  The present invention has the following effects. That is, in an immersion type exposure apparatus, even if contaminants adhere to the light exit end of the optical lens unit, contaminants can be removed by jetting cleaning liquid, etc., and high-precision exposure processing is always performed in a clean state. Is possible. Further, this exposure makes it possible to manufacture a highly reliable semiconductor device with a high yield.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention prevents the lens from being contaminated by this contaminated water. Here, a scanner using a KrF excimer laser as a light source will be described as an exposure apparatus, and a semiconductor wafer used for device manufacture will be described as an exposure target. However, the exposure machine can be used with various light sources such as i-line or ArF excimer laser, and the object to be exposed can be applied to a glass substrate for display, and is not limited to this example.

  1A and 1B are schematic views for explaining an exposure apparatus according to the present embodiment, in which FIG. 1A shows a state during exposure, and FIG. 1B shows a state during cleaning. That is, the exposure apparatus 1 is an immersion type exposure apparatus that performs exposure while a liquid is filled between the light emitting end 2a of the optical lens unit 2 and the substrate (wafer W) to be exposed. .

  Accordingly, as shown in FIG. 1A, a water tank 3 is provided around a movable stage S on which a wafer W is placed, and a liquid L such as pure water is placed in the water tank 3 for light. The liquid L is filled between the emission end 2 a and the wafer W. When exposure is performed, for example, scan exposure is performed by moving the stage S in a predetermined direction while irradiating the wafer W with light through a mask (not shown) from the light emitting end 2a of the optical lens unit 2 in this state.

  After the exposure, the contaminants adhering to the light emitting end 2a of the optical lens unit 2 are cleaned at a predetermined timing. In the exposure apparatus 1 of this embodiment, the liquid L is discharged from the water tank 3 after exposure, and the stage S and the water tank 3 are moved outward from the position of the optical lens unit 2 as shown in FIG. The cleaning nozzle 10 and the like extend to the lower part of the light emitting end 2a, and from here the cleaning liquid CL is sprayed onto the surface of the light emitting end 2a.

  Accordingly, the cleaning nozzle 10 and the like are provided in a lower part of the light emitting end 2a so as to be able to advance and retract, and are configured to extend only when cleaning is performed and to be retracted after cleaning. Thereby, the light emitting end 2a of the optical lens unit 2 can be cleaned without interfering with the water tank 3.

  Further, in the exposure apparatus 1 of the present embodiment, the cleaning nozzle 10 and the gas nozzle 11 that ejects gas toward the light emitting end 2a and the brush 12 that can directly polish the surface of the light emitting end 2a are provided to be able to advance and retreat. ing. The cleaning nozzle 10, the gas nozzle 11, and the brush 12 may all be provided, or any one or more of them may be provided.

  To clean the light emitting end 2a of the optical lens unit 2, the following procedure is used. In other words, the wafer W is frequently replaced every time exposure is completed, but the cleaning timing is appropriately set such as when each wafer W is replaced, after a predetermined number of exposures, or after a predetermined time exposure. It is preferable that the exposure for one lot is completed.

  After the exposure, after the liquid L is discharged from the water tank 3 shown in FIG. 1A, the water tank 3 and the stage S move from the position directly below the lens to the wafer transfer position. Thereafter, the cleaning nozzle 10 attached at a position where it does not interfere with the moving range of the stage S or the optical system extends below the light emitting end 2a, and the cleaning liquid CL is sprayed from the cleaning nozzle 10 toward the light emitting end 2a. Although the cleaning liquid CL is close to the liquid L used for immersion, for example, the same liquid (for example, pure water) as the liquid L used for immersion is used.

  If it is a normal contaminated liquid, it can be almost removed by spraying the cleaning liquid CL from the cleaning nozzle 10. However, when the liquid L used for the immersion is, for example, a highly volatile liquid or when it is left uncleaned for some time due to a device trouble, the liquid L evaporates and strongly contaminates the light emitting end 2a. When a substance is attached, there is a possibility that it cannot be removed only by cleaning with the cleaning liquid CL.

  In order to prepare for such a case, a brush 12 or a similar cleaning tool is attached, and when cleaning is performed in the same manner as the nozzle, it extends below the light emitting end 2a, and the surface of the light emitting end 2a is directly cleaned. May be.

Further, the gas nozzle 11 for blowing dry air, N ₂ or the like can be attached so as to be able to advance and retreat in the same manner as the cleaning nozzle 10 for the purpose of drying the liquid droplets after cleaning. As an apparatus for cleaning, the cleaning nozzle 10 that sprays the cleaning liquid CL is the most effective, and the brush 12 and the gas nozzle 11 that sprays the gas remove contamination only by the cleaning liquid CL depending on the properties of the liquid used and the structure of the wafer W. You may make it attach when it is not done.

  FIG. 2 is a schematic plan view for explaining the arrangement of each nozzle and brush. That is, at the time of exposure, the stage S is disposed below the lens and moves within the stage operating range indicated by a broken line in the drawing. Accordingly, the cleaning nozzle 10, the gas nozzle 11, and the brush 12 are arranged outside the stage operating range and are in a standby state.

  On the other hand, when the wafer W is exchanged after the exposure is completed, the stage S is moved from the lower side of the lens to the outside. As a result, a space is created below the lens, and the cleaning nozzle 10, the gas nozzle 11, and the brush 12 can be extended below the lens.

  FIG. 3 is a schematic diagram illustrating a brush advance / retreat mechanism. As shown in FIG. 3A, the arm 12a of the brush 12 can be folded, and can be extended to the lower side of the lens by extending the arm 12a during cleaning. On the other hand, as shown in FIG. 3B, the arm 12a is folded during standby so as to escape from the stage operating range so as not to obstruct the stage movement during exposure. This advance / retreat mechanism is the same for the cleaning nozzle and the gas nozzle.

  FIG. 4 is a schematic plan view showing a state where each nozzle and brush arm are extended. Since the stage S on which the wafer W is placed is moved outward from the stage operating range during cleaning, the arms of the cleaning nozzle 10, the gas nozzle 11, and the brush 12 are extended so that the tip of the cleaning nozzle 10 and the gas nozzle 11 are below the lens. It is possible to dispose the tip and the brush 12.

  In addition, after the cleaning is completed, the arms of the cleaning nozzle 10, the gas nozzle 11, and the brush 12 can be folded to move out of the stage operating range, and the stage S or the water tank 3 on which the next wafer W is placed can be moved. It is possible to return the lens downward.

  In addition to the case where the cleaning is performed after the predetermined number of exposures as described above, the illuminance is detected from the light exit end of the optical lens unit by an illuminance sensor or the like, and the predetermined illuminance or less. Cleaning may be carried out when

  In this case, an illuminance sensor is provided so that it can be advanced and retracted by a foldable arm similar to each of the nozzles 10, 11 and the brush 12, and the illuminance of light emitted from the light emitting end 2a by extending the arm when detecting the illuminance. Should be detected. As a result, cleaning can be performed only when dirt that affects exposure is attached, and an efficient cleaning operation can be performed.

  Next, another embodiment will be described. FIG. 5 is a schematic diagram for explaining another embodiment. In this embodiment, the cover 4 is attached to the light emitting end 2 a of the optical lens unit 2. In the embodiment described above, it is possible to prevent contamination of the lens (light emitting end 2a) due to the substance dissolved in the liquid. However, there is a concern that the lens may be damaged by spraying gas or cleaning liquid directly on the lens or rubbing with a brush. These effects can be minimized by adjusting the material and pressure of the brush (including gas and liquid), but depending on the type of contaminant, there is a possibility that more pressure is required. In order to cope with such a case, in the example shown in FIG. 5A, a cover 4 having a cover glass 4a transparent to exposure light is attached to the tip of the lens.

  The cover 4 is, for example, a cover glass 4a made of quartz in the case of a KrF or ArF scanner, and is attached to a metal cover frame 4b as shown in FIG. 5B. When liquid enters the inside, there is a possibility of contamination of the optical system, and therefore, the structure is sealed with a rubber O-ring 4c or the like between the light emitting end 2a.

  For attaching the cover 4 to the light emitting end 2a, for example, a screw thread 4d is provided on the inner surface of the cover frame 4b and screwed. As for the cleaning after the cover 4 is attached, cleaning processing such as cleaning liquid ejection from the cleaning nozzle, gas ejection from the gas nozzle, and removal of dirt with a brush is performed in the same manner as in the above-described embodiment.

  Further, when the cover glass 4a is scratched or dirty so as not to be removed, the cover 4 can be detached from the light emitting end 2a and a new cover 4 can be attached.

  Further, the cover 4 may be easily attached and detached by a movable claw method as shown in FIG. 6 in addition to the screwing method by the thread 4d. In this case, the claw 4f is protruded from the inner surface of the cover frame 4b by urging by the leaf spring 4e as shown in FIG. 6A, and the claw 4f is fitted to the outer surface of the light emitting end of the optical lens portion. Make a hole that can be made.

  When attaching / detaching, an attaching / detaching tool 5 as shown in FIG. 6B is used. That is, the tip of the detachable tool 5 is an arm 5a that can be opened and closed. The cover frame 4b of the cover 4 is disposed in the arm 5a with the arm 5a opened, and the cover frame 4b is moved outward by closing the arm 5a. Hold it so that it is pinched.

  Further, while holding the cover frame 4b by the arm 5a, the projection 5b provided inside the arm 5a enters the hole 4g of the cover frame 4b and presses one end of the leaf spring 4e. The claw 4f is opened by the pressing of the leaf spring 4e, and the cover 4 can be attached and detached.

  On the other hand, when the arm 5a is opened with the cover 4 attached to the light emitting end 2a, the pressing of the leaf spring 4e by the projection 5b is released, the claw 4f is closed, and the claw 4f is fitted in the hole provided in the light emitting end 2a. And become fixed.

  Note that the replacement work by the detachable tool 5 may be performed manually or automatically using a robot having a movable arm. The cover 4 is also waterproofed with an O-ring 4c and the like as before.

  In the example in which the cover 4 is attached to the light emitting end 2a, a space is generated between the light emitting end 2a and the cover glass 4a. However, a liquid may be sealed in this space as necessary.

  By adopting these mechanisms described above, it is possible to prevent contamination of the lens (light emitting end 2a) in the immersion type exposure apparatus 1.

  As the timing of cleaning performed by the exposure apparatus 1 according to the present embodiment, it is not necessary to perform cover replacement or cleaning every time continuous exposure is performed, but at least one lot of exposure is completed and the next exposure is completed. It is desirable to do this when there is time when the device is not in operation.

Also,
The cleaning method by spraying the cleaning liquid directly onto the lens is the most effective. However, depending on the target exposure object, resist, etc., there is a possibility that contamination that cannot be removed by spraying the cleaning liquid may occur. In that case, cleaning with a brush is effective.

  Furthermore, in the case of being left for a while after exposure, dust in the air (not 0 even in a clean room) may adhere to the wet lens surface and adhere strongly after drying. For this purpose, a function of forcibly drying by blowing gas from a gas nozzle is also effective. It is also possible to blow off foreign matter by blowing gas.

  Repeating the above operations, particularly brush cleaning, may damage the lens surface. In order to prevent this, as described above, a cover 4 transparent to the exposure light is attached to the tip of the lens, and this can be handled by cleaning. Further, in the case of the cover 4, it can be replaced if it is damaged. Furthermore, if it is worried that the cover 4 will be frequently scratched, the cover 4 can be easily attached and detached, and some of the same cover 4 can be prepared and stocked and replaced periodically.

  Such an exposure apparatus 1 of the present embodiment is desirably applied mainly in an exposure process in a manufacturing method of a semiconductor device. That is, when an immersion type exposure apparatus is used in the exposure process, by using the exposure apparatus 1 according to the present embodiment, contaminants attached to the light emitting end 2a of the optical lens unit 2 can be effectively removed, and accuracy is improved. High exposure makes it possible to achieve fine processing of semiconductor devices, improved reliability, and the like.

  In the above description, an example is shown in which the water tank 3 is moved from the lower side of the lens to the outside together with the stage S for cleaning. However, the present invention can be applied to an exposure apparatus in which only the stage S moves. In this case, it is only necessary to secure a space below the lens so that the water tank 3 moves downward or the lens moves upward and each nozzle and brush does not interfere with the water tank 3.

It is a schematic diagram explaining the exposure apparatus which concerns on this embodiment. It is a schematic plan view explaining arrangement | positioning of each nozzle and a brush. It is a schematic diagram explaining the advancing / retreating mechanism of a brush. It is a schematic plan view which shows the state which the arm of each nozzle and brush extended. It is a schematic diagram explaining other embodiment. It is a schematic diagram explaining the example of a movable nail | claw system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus, 2 ... Optical lens part, 2a ... Light emission end, 3 ... Water tank, 4 ... Cover, 5 ... Detachable tool, CL ... Cleaning liquid, L ... Liquid, S ... Stage, W ... Wafer

Claims (7)

In an exposure apparatus that performs exposure in a state where a liquid is filled between the light emitting end of the optical lens unit and the substrate to be exposed,
An exposure apparatus, wherein a cleaning nozzle that jets a cleaning liquid toward a light emitting end of the optical lens unit is provided in a lower part of the light emitting end so as to advance and retreat. In an exposure apparatus that performs exposure in a state where a liquid is filled between the light emitting end of the optical lens unit and the substrate to be exposed,
An exposure apparatus, wherein a gas nozzle that ejects gas toward the light exit end of the optical lens unit is provided in a lower part of the light exit end so as to be able to advance and retreat. In an exposure apparatus that performs exposure in a state where a liquid is filled between the light emitting end of the optical lens unit and the substrate to be exposed,
An exposure apparatus, wherein a brush for removing dirt on the light exit end of the optical lens portion is provided in a lower portion of the light exit end so as to be able to advance and retract. In an exposure apparatus that performs exposure in a state where a liquid is filled between the light emitting end of the optical lens unit and the substrate to be exposed,
An exposure apparatus, wherein a replaceable cover is provided at a light exit end of the optical lens unit. In a manufacturing method of a semiconductor device including a step of performing exposure in a state where a liquid is filled between a light emitting end in an optical lens portion and a substrate to be exposed,
A method of manufacturing a semiconductor device, wherein after the exposure, a cleaning liquid is ejected toward the light exit end of the optical lens portion to clean the light exit end of the optical lens portion. The method of manufacturing a semiconductor device according to claim 5, wherein the cleaning liquid is jetted to clean the light emitting end of the optical lens unit, and then the cleaning liquid is blown off by spraying a predetermined gas. The method of manufacturing a semiconductor device according to claim 5, wherein the cleaning liquid is ejected to clean the light emitting end of the optical lens unit, and then the surface of the light emitting end is cleaned with a brush.

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