JP2010114344A - Exposure device and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device using light such as EUV light and capable of adjusting positioning on the illumination side without being complicated. <P>SOLUTION: The exposure device includes: an illumination optical system (IL) for illuminating a reflection type mask (M) with light from a light source (1); a projection optical system (PL) for projecting a pattern of the mask onto a photosensitive substrate (W); a reflection mirror (3) located in an optical path between the illumination optical system and the mask for deflecting the light from the illumination optical system to the mask; and an adjusting mechanism (11, 12) for adjusting at least one of the position and the direction of the reflection surface of the reflection mirror. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and a device manufacturing method. More specifically, the present invention relates to an exposure apparatus that transfers a circuit pattern on a mask onto a photosensitive substrate by using, for example, EUV light by a mirror projection method.

  2. Description of the Related Art Conventionally, an exposure apparatus using EUV (Extreme UltraViolet) light having a wavelength of about 5 to 40 nm has been attracting attention as an exposure apparatus used for manufacturing semiconductor elements. When EUV light is used as the exposure light, there is no transmissive optical material and refractive optical material that can be used. Therefore, a reflective mask is used, and a reflective optical system (an optical system composed only of a reflective member) is used as a projection optical system. Will be used.

  The inventor of the present invention proposes a reflection optical system having an entrance pupil on the opposite side of the optical system across the object plane as a projection optical system (imaging optical system) applicable to an exposure apparatus using EUV light. (See Patent Document 1). Hereinafter, in this specification, “an imaging optical system having an entrance pupil on the opposite side of the optical system across the object plane” is referred to as an “inverted pupil optical system”.

JP 2004-170869 A

  When an exposure apparatus is configured using a projection optical system as an inverse pupil optical system, it is necessary to optically combine a light source, an illumination optical system, a projection optical system, and the like with required accuracy. Here, the light source is a heavy object of several tons, and the illumination optical system is an optical system including a pair of fly-eye mirrors. Therefore, it is difficult to incorporate the light source and the illumination optical system into the apparatus with high accuracy, and positioning adjustment is often required on the illumination side after the assembly.

  However, it is difficult to apply the adjustment mechanism to a light source that is a heavy object. In addition, in the illumination optical system, it is necessary to adjust while maintaining the relative positional relationship between one fly-eye mirror and the other fly-eye mirror. Therefore, if the adjustment mechanism is applied to the fly-eye mirror, the apparatus may be complicated. There is.

  The present invention has been made in view of the above-described problems. For example, the present invention provides an exposure apparatus that uses EUV light and that can perform positioning adjustment on the illumination side without complicating the apparatus. With the goal.

In order to solve the above-described problems, the first aspect of the present invention includes an illumination optical system that illuminates a reflective mask with light from a light source, and a projection optical system that projects the mask pattern onto a photosensitive substrate. In the exposure apparatus
A reflector that is disposed in an optical path between the illumination optical system and the mask and deflects light from the illumination optical system to guide the light to the mask;
An exposure apparatus is provided that includes an adjustment mechanism that adjusts at least one of a position and an orientation of a reflection surface of the reflection mirror.

In the second embodiment of the present invention, using the exposure apparatus of the first embodiment, an exposure step of exposing the photosensitive substrate with the pattern of the mask;
Developing the photosensitive substrate to which the pattern has been transferred, and forming a mask layer having a shape corresponding to the pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

  In the exposure apparatus of the present invention, the adjusting mechanism is applied to a reflecting mirror that is arranged in the optical path between the illumination optical system and the reflective mask and has a simple configuration. Since the structure which adjusts at least one of these is employ | adopted, the positioning adjustment by the side of illumination can be performed, without complicating an apparatus. In this case, by using EUV light as the exposure light, the mask pattern can be projected and exposed on the photosensitive substrate with high resolution, and thus a highly accurate device can be manufactured.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the Z axis along the normal direction of the exposure surface (transfer surface) of the wafer W, which is a photosensitive substrate, and the Y axis in the direction parallel to the paper surface of FIG. In the W exposure plane, the X axis is set in a direction perpendicular to the paper surface of FIG.

  The exposure apparatus of FIG. 1 includes, for example, a laser plasma X-ray source as a light source 1 for supplying exposure light. As the light source 1, a discharge plasma light source or another X-ray source can be used. The light emitted from the light source 1 enters the illumination optical system IL through a wavelength selection filter (not shown) arranged as necessary. The wavelength selection filter has a characteristic of selectively transmitting only EUV light having a predetermined wavelength (for example, 13.5 nm) from light supplied from the light source 1 and blocking transmission of other wavelength light.

  The EUV light that has passed through the wavelength selection filter is guided to an optical integrator composed of a pair of fly-eye mirrors 2a and 2b. The fly-eye mirrors 2a and 2b are configured by, for example, arranging a large number of concave mirror elements having an arcuate outer shape vertically and horizontally and densely. For the detailed configuration and operation of the fly-eye mirrors 2a and 2b, reference can be made to, for example, Japanese Patent Laid-Open No. 11-312638.

  Thus, a substantial surface light source having a predetermined shape is formed in the vicinity of the reflecting surface of the second fly-eye mirror 2b. This substantial surface light source is formed at the exit pupil position of the illumination optical system IL composed of a pair of fly-eye mirrors 2a and 2b. The exit pupil position of the illumination optical system IL (that is, the position in the vicinity of the reflection surface of the second fly's eye mirror 2b) coincides with the position of the entrance pupil of the projection optical system PL configured as an inverse pupil optical system.

  The light from the substantial surface light source, that is, the light emitted from the illumination optical system IL is deflected by the reflecting mirror 3, and is then passed through the field stop 4 disposed substantially parallel to and close to the reflective mask M. Thus, an arcuate illumination area is formed on the mask M. Thus, the light source 1 and the illumination optical system IL (2a, 2b) constitute an illumination system for Koehler illumination of the mask M provided with a predetermined pattern.

  The mask M is held by a mask stage MS that can move along the Y direction so that its pattern surface extends along the XY plane. The movement of the mask stage MS is measured by a laser interferometer (not shown). On the mask M, as shown in FIG. 2, for example, an arcuate illumination region IR symmetric with respect to the Y axis is formed. The outer shape of the arcuate illumination region IR formed on the mask M is defined by the arcuate opening (light transmission part) 4a of the field stop 4.

  As an example, the projection optical system PL includes a first reflective imaging optical system that forms an intermediate image of the pattern of the mask M, a second reflective imaging optical system that re-images light from the intermediate image on the wafer W, and It is comprised by. The first reflective imaging optical system is constituted by four reflecting mirrors, and the second reflective imaging optical system is constituted by two reflecting mirrors. The projection optical system PL is located at a position away from the object plane by a finite distance on the opposite side of the optical system across the object plane (position of the pattern surface of the mask M) (exit pupil position of the illumination optical system IL: second fly-eye mirror). 2b is a reflection optical system having an entrance pupil at a position near the reflection surface 2b, and is a telecentric optical system on the wafer side (image side).

  The reflected light from the mask M forms a pattern image of the mask M on the wafer W, which is a photosensitive substrate, via the projection optical system PL. That is, on the wafer W, an arc-shaped effective imaging region ER that is symmetric with respect to the Y axis is formed corresponding to the arc-shaped illumination region IR on the mask M, as shown in FIG. Specifically, an arc-shaped effective imaging region ER is formed in contact with the image circle IF in a circular region (image circle) IF centered on the optical axis AX of the projection optical system PL.

  The wafer W is held by a wafer stage WS that can move two-dimensionally along the X and Y directions so that the exposure surface extends along the XY plane. The movement of the wafer stage WS is measured by a laser interferometer (not shown) as in the mask stage MS. Thus, the scan exposure (scan exposure) is performed while moving the mask stage MS and the wafer stage WS along the Y direction, that is, while relatively moving the mask M and the wafer W along the Y direction with respect to the projection optical system PL. As a result, the pattern of the mask M is transferred to one exposure region of the wafer W.

  At this time, when the projection magnification (transfer magnification) of the projection optical system PL is 1/4, the scanning speed is set with the moving speed of the wafer stage WS set to 1/4 of the moving speed of the mask stage MS. Further, the pattern of the mask M is sequentially transferred to each exposure region of the wafer W by repeating the scanning exposure while moving the wafer stage WS two-dimensionally along the X direction and the Y direction.

  When the projection optical system PL as an inverse pupil optical system is applied to an exposure apparatus that uses EUV light, the reflecting mirror 3 is disposed in the optical path between the illumination optical system IL and the reflective mask M, and this reflecting mirror 3 Therefore, a configuration in which light from the illumination optical system IL is deflected and guided to the mask M is employed. If the reflecting mirror 3 is not interposed, the entrance pupil of the projection optical system PL is positioned in the optical path of the projection optical system PL itself by the action of the reflective mask M, and the entrance pupil of the projection optical system PL is This is because the position cannot be matched with the position of the exit pupil of the illumination optical system IL. The reflecting mirror 3 has, for example, a planar reflecting surface, and the deflection angle formed by the traveling direction of the light incident on the reflecting mirror 3 and the traveling direction of the light deflected by the reflecting mirror 3 is smaller than 90 degrees. In other words, the reflecting mirror 3 is an oblique incidence mirror.

  As described above, it is difficult to incorporate the light source 1 and the illumination optical system IL into the apparatus with high accuracy, and positioning adjustment is often required on the illumination side after incorporation. For example, as shown in FIG. 2, an illumination light beam ILa having an arc-shaped cross section that is substantially similar to the outer shape of the opening 4a of the field stop 4 and slightly larger than the opening 4a is required for the opening 4a. Although it is necessary to make it enter into a position by a required angle, it is difficult to satisfy | fill the required precision regarding the position and angle of illumination light beam ILa, without using a certain adjustment mechanism.

  However, it is difficult to apply the adjustment mechanism to the light source 1 that is a heavy object. In the illumination optical system IL including the pair of fly-eye mirrors 2a and 2b, the relative positional relationship between each mirror element of the first fly-eye mirror 2a and each mirror element of the second fly-eye mirror 2b is maintained. Since it is necessary to adjust, if an adjustment mechanism is applied to the fly-eye mirrors 2a and 2b, the apparatus may be complicated.

  In this embodiment, the structure which applies an adjustment mechanism to the reflective mirror 3 is employ | adopted. Specifically, as shown in FIGS. 1 and 4, as an adjustment mechanism, a driving unit 11 that changes the position and orientation of the reflecting surface 3 a of the reflecting mirror 3 and a control unit 12 that controls the driving unit 11 are provided. Have. The drive unit 11 includes a plurality of actuators (not shown) that operate based on a control signal from the control unit 12, for example, and is positioned along the normal direction of the reflecting surface 3a of the reflecting mirror 3, that is, an arrow in FIG. The position of the reflecting surface 3a along the direction indicated by Fz is changed.

  Further, the drive unit 11 follows the control signal from the control unit 12 so that the direction of the reflection surface 3a around the y direction perpendicular to the z direction, which is the normal direction, and parallel to the paper surface of FIG. The direction of the reflecting surface 3a is changed along the rotation direction indicated by Fy. Further, the drive unit 11 reflects the reflection surface 3a in the direction of the reflection surface 3a around the x direction perpendicular to the y direction, that is, the reflection direction along the rotation direction indicated by the arrow Fx in FIG. 4 according to the control signal from the control unit 12. The direction of the surface 3a is changed.

  In the present embodiment, after the light source 1 and the illumination optical system IL are incorporated into the apparatus, the position of the reflecting surface 3a of the reflecting mirror 3 is changed along the x direction by the action of the adjusting mechanism (11, 12), so that the field stop The position of the illumination light beam ILa with respect to the four openings 4a can be adjusted along the Y direction. Further, by the action of the adjusting mechanism (11, 12), the direction of the reflecting surface 3a of the reflecting mirror 3 is appropriately changed around the y direction, and the position of the illumination light beam ILa with respect to the opening 4a is adjusted along the X direction. The tilt of the illumination light beam ILa with respect to the opening 4a can be adjusted in the X direction. Further, by the action of the adjusting mechanism (11, 12), the direction of the reflecting surface 3a of the reflecting mirror 3 is appropriately changed around the x direction, and the position of the illumination light beam ILa with respect to the opening 4a is adjusted along the Y direction. The tilt of the illumination light beam ILa with respect to the opening 4a in the Y direction can be adjusted.

  Thus, in the present embodiment, the adjustment mechanism (11) applied to the reflecting mirror 3 that is disposed in the optical path between the illumination optical system IL and the mask M and deflects the light from the illumination optical system IL and guides it to the mask M. , 12), after the light source 1, the illumination optical system IL, the projection optical system PL, and the like are incorporated in the apparatus, the required positioning adjustment can be performed on the illumination side. That is, in the exposure apparatus of the present embodiment using EUV light, the adjustment mechanism is applied to the reflecting mirror 3 that is arranged in the optical path between the illumination optical system IL and the reflective mask M and has a simple configuration. Therefore, positioning adjustment on the illumination side can be performed without complicating the apparatus.

  In particular, in the present embodiment, the reflecting mirror 3 is a grazing incidence mirror, and since the incident angle range in which a required reflectance can be ensured is relatively wide, the reflecting surface of the reflecting mirror 3 is adjusted by the adjusting mechanism (11, 12). Even if the position and orientation of 3a are changed by a required amount, there is an advantage that the influence on the apparatus performance is relatively small. In the present embodiment, since the EUV light is used as the exposure light, the illumination optical path is set to a vacuum environment. However, based on the control signal (electric signal) from the control unit 12, the reflection surface 3a of the reflecting mirror 3 Since the position and orientation are controlled, necessary adjustments can be made without destroying the vacuum environment.

  In the above description, the position and orientation of the reflecting surface 3a of the reflecting mirror 3 are changed by the action of the adjusting mechanism (11, 12). However, the present invention is not limited to this, and the effect of the present invention can be obtained even in a configuration in which at least one of the position and orientation of the reflecting surface 3a of the reflecting mirror 3 is adjusted.

  The exposure apparatus of the above-described embodiment is manufactured by assembling various subsystems including the respective constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Is done. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  Next, a device manufacturing method using the exposure apparatus according to the above-described embodiment will be described. FIG. 5 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 5, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a semiconductor device substrate (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the exposure apparatus of the above-described embodiment, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W (step S44: exposure process), and the transfer of the wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred is performed (step S46: development process). Thereafter, using the resist pattern generated on the surface of the wafer W in step S46 as a mask, processing such as etching is performed on the surface of the wafer W (step S48: processing step).

  Here, the resist pattern is a photoresist layer in which unevenness having a shape corresponding to the pattern transferred by the exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. is there. In step S48, the surface of the wafer W is processed through this resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W or film formation of a metal film or the like. In step S44, the exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as a photosensitive substrate.

  In the above-described embodiment, a laser plasma X-ray source is used as a light source for supplying EUV light. However, the present invention is not limited to this, and for example, synchrotron radiation (SOR) light is used as EUV light. You can also.

  In the above-described embodiment, the present invention is applied to an exposure apparatus having a light source for supplying EUV light. However, the present invention is not limited to this, and a light source that supplies light having a wavelength other than EUV light. The present invention can also be applied to an exposure apparatus having

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure which shows a mode that the circular arc-shaped illumination area prescribed | regulated to the opening part of a field stop is formed on a mask. It is a figure which shows a mode that an arc-shaped effective image formation area | region is formed on a wafer. It is a figure explaining the effect | action of the adjustment mechanism applied to the reflecting mirror. It is a figure which shows the flowchart about an example of the method at the time of obtaining the semiconductor device as a microdevice.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser plasma X-ray source 2a, 2b Fly eye mirror 3 Reflection mirror 4 Field stop 11 Drive part 12 Control part IL Illumination optical system M Mask MS Mask stage PL Projection optical system W Wafer WS Wafer stage

Claims (10)

In an exposure apparatus comprising an illumination optical system that illuminates a reflective mask with light from a light source, and a projection optical system that projects the mask pattern onto a photosensitive substrate,
A reflector that is disposed in an optical path between the illumination optical system and the mask and deflects light from the illumination optical system to guide the light to the mask;
An exposure apparatus comprising: an adjustment mechanism that adjusts at least one of a position and an orientation of a reflecting surface of the reflecting mirror. The said adjustment mechanism has a drive part which changes at least one of the position and direction of the said reflective surface of the said reflective mirror, and a control part which controls this drive part, The Claim 1 characterized by the above-mentioned. Exposure device. The drive unit includes a position along the normal direction of the reflecting surface of the reflecting mirror, an orientation of the reflecting surface around a first direction orthogonal to the normal direction on the reflecting surface, and the first position on the reflecting surface. 3. The exposure apparatus according to claim 2, wherein at least one of the orientations of the reflecting surface around a second direction orthogonal to the one direction is changed. 4. The deflection angle formed by the traveling direction of light incident on the reflecting mirror and the traveling direction of light deflected by the reflecting mirror is smaller than 90 degrees. 5. Exposure equipment. The exposure apparatus according to claim 1, wherein the reflecting mirror has a planar reflecting surface. The exposure apparatus according to claim 1, wherein the projection optical system is a reflection optical system. The exposure apparatus according to claim 6, wherein the reflection optical system has an entrance pupil on the opposite side of the reflection optical system with the mask interposed therebetween. 8. The exposure apparatus according to claim 1, wherein the light supplied from the light source is EUV light having a wavelength of 5 nm to 40 nm. 9. The projection exposure of a pattern of the mask on the photosensitive substrate by moving the mask and the photosensitive substrate relative to the projection optical system. 10. Exposure equipment. An exposure step of exposing the photosensitive substrate with a pattern of the mask using the exposure apparatus according to claim 1;
Developing the photosensitive substrate to which the pattern has been transferred, and forming a mask layer having a shape corresponding to the pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

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