WO2012060083A1

WO2012060083A1 - Illumination device, exposure device, program, and illumination method

Info

Publication number: WO2012060083A1
Application number: PCT/JP2011/006080
Authority: WO
Inventors: 尚憲北; 嘉彦藤村; 正康澤田; 則之松尾
Original assignee: 株式会社ニコン
Priority date: 2010-11-05
Filing date: 2011-10-31
Publication date: 2012-05-10

Abstract

The present invention accurately generates a desired illumination pattern. An illumination device for illuminating a surface to be irradiated by light from a light source comprises: a spatial light modulation element for projecting a plurality of reflected light beams onto a projection surface and forming an illumination pattern, the spatial light modulation element having a plurality of reflecting mirrors for reflecting incident light from a light source at individually set angles of reflection to emit the reflected light beams; a calculation unit for calculating the respective angles of reflection of the reflecting mirrors under the condition of further reducing mutual interference among the reflected light beams for forming the illumination pattern; and a drive unit for driving the reflecting mirrors and setting, for each of the reflecting mirrors, the angles of reflection calculated by the calculation unit.

Description

Illumination apparatus, exposure apparatus, program, and illumination method

The present invention relates to an illumination apparatus, an exposure apparatus, a program, and an illumination method.

There is an exposure apparatus that can form an illumination pattern having an arbitrary intensity distribution (see Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] JP 2002-353105 A

When a spatial light modulator such as a movable multi-mirror is used, the illumination pattern formed may include an illuminance distribution that cannot be expected only by the concept of geometrical reflection by the mirror.

According to the first aspect, the illumination device illuminates the irradiated surface with light from the light source, and the plurality of reflections that reflect the incident light source light at individually set reflection angles and emit a plurality of reflected lights A spatial light modulation element having a mirror and projecting a plurality of reflected lights onto a projection surface to form an illumination pattern; and a plurality of reflected lights forming a lighting pattern under a condition for reducing interference between the reflected lights. Provided is an illuminating device including a calculating unit that calculates a reflection angle of each reflecting mirror, and a driving unit that drives a plurality of reflecting mirrors and sets the reflection angles calculated by the calculating unit to each of the reflecting mirrors. . Moreover, according to a 2nd aspect, an exposure apparatus provided with the said illuminating device is provided.

According to the third aspect, the illumination apparatus includes the plurality of reflecting mirrors that reflect the incident light source light at individually set reflection angles and emit a plurality of reflected lights, and projects the plurality of reflected lights onto the projection surface to illuminate. A spatial light modulation element that forms a pattern, a calculation unit that calculates a reflection angle set for each of the plurality of reflection mirrors, and a plurality of reflection mirrors that drive the reflection angles calculated by the calculation units. A control program for controlling an illuminating device including a driving unit set to each of the plurality of reflecting mirrors under a condition for reducing interference between a plurality of reflected lights forming an illumination pattern. A program for calculating is provided.

Further, according to the fourth aspect, under the condition that the interference between the plurality of reflected lights forming the illumination pattern is made smaller, the calculation stage for calculating the reflection angle of each of the plurality of reflecting mirrors, and the plurality of reflecting mirrors, Driving and setting the reflection angle calculated in the calculation step to each of the plurality of reflecting mirrors, reflecting the incident light source light at the reflection angle set individually, and emitting a plurality of reflected lights, And a forming step of forming an illumination pattern by projecting the reflected light on the projection surface.

Further, according to the fifth aspect, the illumination device illuminates the irradiated surface with light from the light source, and a plurality of reflected light beams are emitted by reflecting incident light source light at individually set reflection angles. A spatial light modulator that projects a plurality of reflected light onto a projection surface to form an illumination pattern, and evaluates the interference between the plurality of reflected lights that form the illumination pattern. A calculation unit that calculates a reflection angle of each of the plurality of reflection mirrors so that interference between the plurality of reflected lights is reduced, and a plurality of reflection mirrors are driven to obtain the reflection angles calculated by the calculation unit. An illuminating device provided with the drive part set to each of these is provided. Moreover, according to the 6th aspect, an exposure apparatus provided with the said illuminating device is provided.

In addition, according to the seventh aspect, the light source includes a plurality of reflecting mirrors that reflect the incident light source light at individually set reflection angles and emit a plurality of reflected lights, and project the plurality of reflected lights onto the projection surface. A spatial light modulation element that forms an illumination pattern, a calculation unit that calculates a reflection angle set for each of the plurality of reflection mirrors, and a plurality of reflection mirrors that drive the reflection angles calculated by the calculation unit. A control program for controlling an illuminating device including a drive unit set for each of the mirrors. The control program evaluates interference between a plurality of reflected lights forming an illumination pattern. A program is provided for calculating the reflection angle of each of the plurality of reflecting mirrors so that interference is reduced.

Further, according to the eighth aspect, the interference between the plurality of reflected lights forming the illumination pattern is evaluated, and each of the plurality of reflecting mirrors is reduced so that the interference between the plurality of reflected lights is reduced based on the evaluation result. A calculation stage for calculating a reflection angle, a driving stage for driving a plurality of reflecting mirrors and setting the reflection angle calculated in the calculation stage for each of the plurality of reflecting mirrors, and a reflection in which incident light source light is individually set There is provided an illumination method including: forming a plurality of reflected lights by reflecting at an angle; and forming a lighting pattern by projecting the plurality of reflected lights onto a projection surface.

According to the ninth aspect, the projection object is illuminated using the illumination method, and light from the illuminated projection object is passed through the projection optical system to form an image of the projection object on the object. An exposure method is provided.

According to the tenth aspect, the exposure method is used to form a pattern on the object; the object on which the pattern is formed is developed, and a mask layer having a shape corresponding to the pattern is formed on the object. Forming a surface of the object; and processing the surface of the object through the mask layer.

The above summary of the invention does not enumerate all necessary features of the present invention. A sub-combination of these feature groups can also be an invention.

1 is a schematic diagram showing the overall structure of an exposure apparatus 100. FIG. 3 is a cross-sectional view schematically showing an individual structure of a reflecting mirror 222. FIG. 3 is a schematic perspective view of a spatial light modulator 220. FIG. FIG. 6 is a diagram illustrating the operation of the spatial light modulator 220. It is a figure which shows the function of the light source part 200 typically. FIG. 3 is a diagram schematically illustrating a function of a spatial light modulator 220. 5 is a graph showing an incident angle distribution of light source light in the spatial light modulator 220. It is a graph which shows the relationship between a reflective mirror space | interval and the magnitude | size of interference. It is a figure which shows an interference generation condition typically. It is a graph which shows the influence of the interference with respect to the area of an illumination pattern. It is a flowchart which shows the setting angle calculation procedure on condition of suppression of interference. It is a figure which shows typically the relationship between the reflective mirror 222 and the light patterns P, Q, and R. FIG. It is a figure which shows typically the method of determining the coordinate of spotlight. It is a figure which shows typically the procedure of the method of determining the coordinate of spotlight. It is a figure which shows typically the other procedure of the method of determining the coordinate of spot light. It is a flowchart which shows the manufacturing process of a microdevice. It is a flowchart which shows the content of a board | substrate process step.

Hereinafter, the present invention will be described through embodiments of the invention. The following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential for the solution of the invention.

FIG. 1 is a schematic diagram showing the overall structure of the exposure apparatus 100. The exposure apparatus 100 includes a light source unit 200, an illumination optical system 300, and a projection optical system 400.

The light source unit 200 includes a light source 110, a control unit 210, a spatial light modulator 220, a prism 230, an imaging optical system 240, a beam splitter 250, and a measurement unit 260. The light source 110 generates illumination light L. The illumination light L generated by the light source 110 has an illuminance distribution according to the characteristics of the light emitting mechanism of the light source 110. For this reason, the illumination light L has the original image I ₁ in a cross section orthogonal to the optical path of the illumination light L.

The illumination light L emitted from the light source 110 enters the prism 230. The prism 230 guides the illumination light L to the spatial light modulator 220 and then emits the light again to the outside.

The control unit 210 includes a drive unit 212 and a calculation unit 214. The calculation unit 214 calculates a setting angle, which will be described later, set in the spatial light modulator 220. The drive unit 212 sets the set angle calculated by the calculation unit 214 in the spatial light modulator 220. The operation of the control unit 210 will be described later. Note that the control unit 210 can load its new operation procedure by mounting the medium 216.

The spatial light modulator 220 modulates the illumination light L incident under the control of the control unit 210. The structure and operation of the spatial light modulator 220 will be described later with reference to other drawings.

The illumination light L emitted from the prism 230 via the spatial light modulator 220 is incident on the illumination optical system 300 at the subsequent stage via the imaging optical system 240. The imaging optical system 240 forms an illumination light image I ₃ on the incident surface 312 of the illumination optical system 300.

The beam splitter 250 is disposed on the optical path of the illumination light L between the imaging optical system 240 and the illumination optical system. The beam splitter 250 separates a part of the illumination light L before entering the illumination optical system 300 and guides it to the measurement unit 260.

The measurement unit 260 measures the image of the illumination light L at a position optically conjugate with the incident surface 312 of the illumination optical system 300. Thereby, the measurement unit 260 measures the same image as the illumination light image I ₃ incident on the illumination optical system 300. Therefore, the control unit 210 can perform feedback control of the spatial light modulator 220 via the drive unit 212 with reference to the illumination light image I ₃ measured by the measurement unit 260. For details of the configuration and operation of the measurement unit 260, reference can be made to, for example, US Patent Application Publication No. 2008/0030707.

The illumination optical system 300 includes a fly-eye lens 310, a condenser optical system 320, a field stop 330, and an imaging optical system 340. A mask stage 420 holding an exposure mask 410 is disposed at the exit end of the illumination optical system 300.

The fly-eye lens 310 includes a large number of lens elements arranged densely in parallel, and forms a secondary light source including illumination light images I ₃ as many as the number of lens elements on the rear focal plane. The condenser optical system 320 condenses the illumination light L emitted from the fly-eye lens 310 and illuminates the field stop 330 in a superimposed manner. In the present embodiment, as the fly eye lens 310, for example, a cylindrical micro fly eye lens disclosed in US Pat. No. 6,913,373 can be used.

The illumination light L that has passed through the field stop 330 forms an irradiation light image I ₄ that is an image of the opening of the field stop 330 on the pattern surface of the exposure mask 410 by the imaging optical system 340. The pattern surface of the exposure mask 410 is optically Fourier-transformed with respect to the exit surface of the fly-eye lens 310. Accordingly, the illumination optical system 300, the pattern surface of the exposure mask 410 disposed at its exit end, Koehler illuminated by illumination light image I _4.

Note that the illuminance distribution formed at the entrance end of the fly-eye lens 310 that is also the entrance surface 312 of the illumination optical system 300 is higher than the overall illuminance distribution of the entire secondary light source formed at the exit end of the fly-eye lens 310. Show correlation. Therefore, the illumination light image I ₃ that the light source unit 200 enters the illumination optical system 300 is also reflected in the illumination light image I ₄ that is the illuminance distribution of the illumination light L that the illumination optical system 300 irradiates the exposure mask 410.

The projection optical system 400 is disposed immediately after the mask stage 420 and includes an aperture stop 430. The aperture stop 430 is disposed at a position optically conjugate with the emission end of the fly-eye lens 310 of the illumination optical system 300. A substrate stage 520 that holds a substrate 510 coated with a photosensitive material is disposed at the exit end of the projection optical system 400. The aperture stop 430 of the projection optical system 400 is a position optically conjugate with the position where the secondary light source is formed in the illumination optical system 300. Thus, the position where the secondary light source is formed in the illumination optical system 300 can be referred to as the illumination pupil plane of the illumination optical system.

The exposure mask 410 held on the mask stage 420 has a mask pattern composed of a region that reflects or transmits the illumination light L irradiated by the illumination optical system 300 and a region that absorbs it. Therefore, by irradiating the illumination light image I ₄ to the exposure mask 410, the projection light image I ₅ produced by the interaction of the illuminance distribution of the illumination light image I ₄ itself as a mask pattern of an exposure mask 410. The projected light image I ₅ is projected onto the photosensitive material of the substrate 510 to form a resist layer having the required pattern on the surface of the substrate 510.

In FIG. 1, the optical path of the illumination light L is drawn in a straight line, but the exposure apparatus 100 is miniaturized by bending the optical path of the illumination light L. Although FIG. 1 depicts the illumination light L so that it passes through the exposure mask 410, a reflective exposure mask 410 may be used.

FIG. 2 is a diagram for explaining the structure of the spatial light modulator 220, and shows a part of the spatial light modulator 220 in an enlarged manner. The spatial light modulator 220 includes a reflecting mirror 222, a substrate 224, a flexure 226, and

electrodes

223 and 225. The reflecting mirror 222 is suspended from the lower surface of the substrate 224 via the flexure 226. The flexure 226 is formed of a material that can be easily deformed. Therefore, the reflecting mirror 222 is supported so as to be swingable with respect to the substrate 224.

One electrode 223 is disposed on the back surface of the reflecting mirror 222 so as to face the substrate 224. The other electrode 225 is disposed on the surface of the substrate 224 so as to face the back surface of the reflecting mirror 222. The electrode 225 disposed on the substrate 224 is divided into a plurality of parts, and a voltage can be applied individually. With such a structure, a voltage can be applied to any of the electrodes 225 on the substrate 224 to cause an electrostatic force to act between the electrodes 223 of the reflecting mirror 222 and to give the required tilt to the reflecting mirror 222. .

FIG. 3 is a schematic perspective view of the spatial light modulator 220. As shown in the figure, the spatial light modulator 220 is formed by arranging a large number of structures including the reflecting mirror 222 and the

electrodes

223 and 225 as described above on a single substrate 224. The plurality of reflecting mirrors 222 individually swing according to the control of the control unit 210. The detailed configuration of the spatial light modulator similar to the spatial light modulator 220 is disclosed in, for example, US Patent Application Publication No. 2009/0097094.

For the purpose of clarifying the drawing, FIG. 3 shows a spatial light modulator 220 including 16 reflecting mirrors 222. However, the spatial light modulator 220 mounted on the exposure apparatus 100 includes a large number of reflecting mirrors 222 according to the accuracy of the pattern to be formed.

FIG. 4 is a partially enlarged view of the light source unit 200 and shows the operation of the light source unit 200 including the spatial light modulator 220. The prism 230 has a pair of reflecting

surfaces

232 and 234. The illumination light L incident on the prism 230 is irradiated toward the spatial light modulator 220 by the one reflecting surface 232.

As already described, the spatial light modulator 220 has a plurality of reflecting mirrors 222 that can be individually swung. Therefore, the control unit 210 controls the spatial light modulator 220 can be formed of any light source image I ₂ corresponding to the request.

The light source image I ₂ emitted from the spatial light modulator 220 is emitted from the prism 230 by the other reflecting surface 234 of the prism 230. The light source image I ₂ emitted from the prism 230 forms an illumination light image I ₃ on the incident surface 312 of the illumination optical system 300 by the imaging optical system 240.

Here, referring again to FIG. 1, the projection surface of the spatial light modulator 220 is a surface that is optically Fourier-transformed with respect to the arrangement surface of the reflecting mirrors 222, and is the incident surface of the fly-eye lens 310. This is a pupil plane of the illumination optical system 300 that is optically conjugate with the above. Therefore, a light intensity distribution similar to the illumination pattern formed on the projection surface is formed on the incident surface of the fly-eye lens 310.

When the number of wavefront divisions by the fly-eye lens 310 is sufficiently large, for example, 10,000 divisions or more, a secondary light source having a light intensity distribution showing a high correlation with the illumination pattern is formed on the exit surface of the fly-eye lens 310. Is done. Therefore, the pattern surface of the exposure mask 410 is Koehler illuminated using the secondary light source formed in the illumination optical system 300 as a light source.

It should be noted that since the exit surface of the fly-eye lens 310 has a Fourier transform relationship with respect to the entrance surface, the projection surface and the pattern surface of the exposure mask 410 appear to be conjugate. When the wavefront division number of the fly-eye lens 310 is large, the overall light intensity distribution formed on the entrance surface of the fly-eye lens and the overall light intensity distribution (pupil intensity) of the entire secondary light source formed on the exit surface. Distribution) shows a high correlation. Therefore, the entrance surface 312 of the fly-eye lens 310 and a surface that is closer to the light source 110 than the entrance surface and is optically conjugate with the entrance surface can also be referred to as an illumination pupil plane.

FIG. 5 is a diagram schematically illustrating the function of the light source unit 200. In the drawing, the curve drawn on the left side of the spatial light modulator 220 shows an example of the intensity distribution of the light source light incident on the spatial light modulator 220. As illustrated, the light source light incident on the spatial light modulator 220 has a constant intensity distribution. However, since this intensity distribution depends on the specifications of the light source 110, it is known in advance.

The rectangular curve described on the right side of the incident surface 312 indicates the intensity distribution of the light patterns P, Q, and R required as the illumination pattern. Each of the light patterns P, Q, and R has a unique intensity and width.

FIG. 6 is a diagram schematically showing the function of the reflecting mirror 222 in the spatial light modulator 220. As already described, the spatial light modulator 220 can individually set the reflection angle for each of the plurality of reflecting mirrors 222. Each of the reflected lights emitted from the individual reflecting mirrors 222 is projected onto the incident surface 312 as spot light. A sub-peak as a Fraunhofer diffraction image appears around each spot light, but it can be ignored because the level is lower than the original peak of the spot light.

For example, when the light patterns P, Q, and R shown in FIG. 5 are formed, the spot light emitted from the reflecting mirror 222 is arranged on the incident surface 312 according to the size and illuminance of each light pattern. In the illustrated example, two spot lights are arranged in each of the light patterns P and R, and six spot lights are arranged in the light pattern Q.

Note that FIG. 6 is a schematic diagram only, and the spatial light modulator 220 includes a large number of reflecting mirrors 222 ranging from several hundred thousand to several million. Thereby, the light source part 200 can form the light pattern which has arbitrary intensity distribution as intended.

However, when an illumination pattern is formed by a large number of spot lights, an unintended intensity distribution may appear. Such an unintentional intensity distribution reduces the accuracy of the illumination pattern on the incident surface 312. One of the causes of such an unintended intensity distribution is an interference effect caused by a plurality of spot lights emitted from the spatial light modulator 220 toward the incident surface 312.

FIG. 7 is a graph showing the relationship between the angular distribution of the light source light incident on the spatial light modulator 220 from the light source 110 and the incident angle on the reflecting mirror 222 of the spatial light modulator 220. The light source light incident on the spatial light modulator 220 is not completely parallel light. For this reason, as shown in the figure, incident angle distribution is inevitably generated, and the spot light formed by one mirror in the spatial light modulator 220 is also thickened accordingly.

FIG. 8 is a graph showing the relationship between the spacing between the reflecting mirrors 222 and the spatial coherence (magnitude of interference) generated between the reflected lights of the reflecting mirrors 222 in the spatial light modulator 220. As shown in the figure, when the distance between a pair of reflecting mirrors 222 is narrow, it means that a significantly large interference occurs.

In other words, if two mirrors are in a relationship in which the distance between the reflecting mirrors 222 that emit the reflected light is separated, the angles thereof are substantially the same, and therefore the spot light formed at substantially the same position. It can be said that there is no mutual interference effect, and that it corresponds to a simple sum of intensity. In the illustrated example, for example, if the size of each reflecting mirror 222 is 50 μm square, strong interference does not occur if the reflecting mirrors 222 are separated by two.

Even when the interval between the reflecting mirrors 222 is wide, strictly speaking, interference occurs. However, when the intensity of interference generated with respect to the accuracy required for the light source unit 200 is negligible, it can be considered that “no interference occurs” for convenience.

FIG. 9 is a diagram schematically showing the interference generation conditions shown in FIG. 7 and FIG. In the figure, the spatial light modulator 220 and the fly-eye lens 310 are arranged facing each other. As a result, the illumination light that has entered the spatial light modulator 220 is reflected by the reflecting mirror 222 and enters the incident surface 312 of the fly-eye lens 310.

For convenience of explanation, individual reflecting mirrors 222 are indicated by reference signs A to D and 1 to 4 attached to the side surface of the spatial light modulator 220. The coordinates a to d and 1 to 4 attached to the side surface of the fly-eye lens 310 represent coordinates indicating a specific area on the incident surface 312. Hereinafter, the coordinates of the specific area are referred to as “pupil plane coordinates”.

The reflected

lights

302 and 304 emitted from the reflecting mirrors D-1 and C-1 are applied to the regions d-1 and c-4 on the incident surface. The reflecting mirrors D-1 and C-1 are adjacent to each other, but the regions d-1 and c-4 are separated from each other. Therefore, the interference generated in the reflected

lights

302 and 304 is small and can be ignored.

Reflected lights

306 and 302 emitted from the reflecting mirrors A-3 and D-1 are applied to the areas a-3 and d-1. The optical paths of the reflected

lights

306 and 302 are substantially parallel to each other, but are separated from the reflecting mirrors A-3 and D-1 and the areas a-3 and d-1. Therefore, the interference generated in the reflected

lights

306 and 302 is small and can be ignored.

The reflected

lights

304 and 305 emitted from the reflecting mirrors C-1 and C-4 are applied to the same region c-4. However, since the reflecting mirrors C-1 and C-4 are separated from each other, interference generated in the reflected

lights

304 and 305 is small and can be ignored.

Reflected lights

303 and 305 emitted from the reflecting mirrors C-4 and D-4 are applied to the regions c-4 and d-3 connected in the diagonal direction. Since the reflecting mirrors C-1 and C-4 are also adjacent, the reflected

lights

303 and 305 cause interference 301 that cannot be ignored.

As described above, when the pair of reflecting mirrors 222 having a narrow interval irradiate the adjacent region on the incident surface 312, interference with a magnitude that cannot be ignored occurs. In other words, when the spot light emitted from the reflecting mirror 222 is arranged on the incident surface 312 as shown in FIG. 6, the light pattern is not affected by the interference by assuming that no interference occurs. Can be formed. Therefore, the calculation unit in the exposure apparatus 100 calculates the set angle set for each of the reflecting mirrors 222 so that the arrangement of the reflected light emitted from the reflecting mirror 222 satisfies the above-described conditions.

Incidentally, as one method of using the exposure apparatus 100, a light source mask optimization method (SMO method: Source and Mask Optimization) that optimizes a mask pattern (reticle pattern) and a light source image together and exposes a fine pattern with high accuracy. There is. In the SMO method, the illumination pattern may include a plurality of light patterns separated from each other. For this reason, the area of each light pattern becomes small.

When the number of occurrences of interference is _expressed as N _coh , and the number of spot lights forming a light pattern (proportional to the area of the light pattern) is expressed as N _p , the relationship between both can be expressed as in Equation 1 below.

FIG. 10 is a graph showing the influence of interference on the area of the illumination pattern as described above. As shown in the figure, when the area of the light pattern is reduced, the occurrence of non-negligible interference is significantly increased. Therefore, in the SMO method, the spot light emitted from the reflecting mirror 222 is arranged on the incident surface 312 while suppressing the occurrence of interference, in other words, the mutual interference of a plurality of reflected lights emitted from the reflecting mirror 222. It is required that the spot light emitted from the reflecting mirror 222 is arranged on the incident surface 312 under the condition of making the size smaller.

Note that the mutual interference between the plurality of reflected lights emitted from the reflecting mirror 222 is made smaller in consideration of interference generated on the incident surface 312 when spot light emitted from the reflecting mirror 222 is arranged on the incident surface 312. The state in which interference generated on the incident surface 312 is suppressed as compared with the case where spot light is arranged without performing this operation can be pointed out.

FIG. 11 is a flowchart showing a set angle calculation procedure under the condition that interference is suppressed. As illustrated, the calculation unit 214 forms an order in descending order of the intensity of the light source light incident on the reflecting mirror 222 (S201). Subsequently, the reflecting mirror 222 having a high intensity of incident light source light is selected as an object to be processed according to the formed order (S202).

The reason is that, as shown in FIG. 5, the light source light incident on the spatial light modulator 220 has an intensity distribution. Therefore, the intensity of the spot light reflected and emitted from the reflecting mirror 222 is also individually different. Here, when the intensity of the spot light is high, the influence on the illumination pattern is large when interference occurs. Further, as will be described later, when there are many spot lights whose arrangement has already been determined, there are restrictions on the arrangement of new spot lights. Therefore, in the exposure apparatus 100, the calculation unit 214 sequentially calculates the reflection angle from the reflecting mirrors 222 from which the light source light with higher illuminance is incident among the plurality of reflecting mirrors 222.

Next, the calculation unit 214 determines the arrangement of the spot light emitted from the selected reflecting mirror 222 on the incident surface 312 (S203). In this determination, first, a position on the entrance surface 312, that is, pupil plane coordinates are assigned for the purpose of forming the obtained light pattern. Subsequently, the interference generated when the spot light is projected onto the assigned pupil plane coordinates is examined (S204).

When it is found that interference that cannot be ignored occurs at this position (S205: NO), the calculation unit 214 calculates the set angle of the reflecting mirror 222 so that the spot light is projected at the position (S206). ). Thereby, a setting angle is determined for the reflecting mirror 222. Subsequently, the calculation unit 214 checks whether there is another reflecting mirror 222 whose setting angle is not yet determined (S207).

When there is no more reflecting mirror 222 for which the setting angle has not been determined (S207: NO), the calculation unit 214 ends the setting angle calculation process, and the driving unit 212 sets the calculated setting angle to each of the reflecting mirrors 222. Set to. If there is still a reflecting mirror 222 for which the setting angle has not been determined (S207: YES), the process returns to step S202 again, and the setting angles are sequentially determined from the reflecting mirror 222 having a high incident intensity of illumination light.

If it is found in step 205 that interference that cannot be ignored occurs (S205: YES), the calculation unit 214 assigns other coordinates to the spot light generated by the reflector 222 (S203). Hereinafter, by repeating the step (S204) of examining the interference generated by the spot light of the reflecting mirror 222, it is possible to form an illumination pattern while suppressing the occurrence of interference.

FIG. 12 is a diagram schematically showing the relationship between the spatial light modulator 220 in which the setting angle of the reflecting mirror 222 is set by the above-described procedure and the light patterns P, Q, and R on the incident surface 312. Circled numbers in the figure indicate the order in which incident light source light intensity is high, that is, the order in which pupil plane coordinates are determined.

As shown in the figure, among the ten spot lights, the arrangement of the spot lights 1 to 8 has already been determined. The determined spot lights are spaced apart from each other on the reflecting mirror 222 side and on the incident surface 312 side, and non-negligible interference does not occur.

However, the ninth and tenth spot lights can be arranged avoiding the condition that causes interference when they are arranged on the incident surface 312 as a part of the light pattern Q (indicated by a one-dot chain line in the drawing). There are no pupil plane coordinates. In such a case, the calculation unit 214 may introduce an additional calculation procedure for the reflector 222 that cannot determine the arrangement of the spot light.

FIG. 13 is a diagram schematically showing a procedure for determining a position (pupil plane coordinates) on the incident surface 312 where the spot light is arranged in the above case. In the illustrated example, the pupil plane coordinates of the third spot light from the higher incident light source light intensity are determined.

Here, when the pupil plane coordinates of the third spot light among the plurality of spot lights shown in (1) cannot be found, the calculation unit 214 calculates the light source light intensity as shown in (2). In the order, the third reflecting mirror 222 and the fourth reflecting mirror 222 are interchanged, and the arrangement of the spot light is determined again. As described above, the arrangement of the spot light may be found by changing the reflection mirror 222 to be processed.

Furthermore, if the spot light arrangement cannot still be found, the calculation unit 214 replaces the third spot light with a spot light emitted by a different reflecting mirror 222 as shown in (3). Hereinafter, the process of arranging the spot light is repeated. As described above, an illumination pattern with less interference can be formed.

FIG. 14 is a diagram schematically showing the flow of the method as described above. As shown in the figure, the calculation unit 214 searches for the arrangement of the spot light in descending order of the incident light source light intensity, and spot light (indicated by a white star) that cannot find an arrangement that does not cause interference is more The arrangement is searched by substituting the lower spot light. Thereafter, the replacement is repeated until the lowest spot light, and if it is still impossible to find an arrangement that does not cause interference, it is determined that interference cannot be avoided.

However, the lower spot light has a low intensity, so the interference generated is weak. Therefore, the calculation unit 214 may arrange the spot light when the generated interference becomes weak according to the accuracy calculated for the light source unit 200. This effectively suppresses the influence of interference.

FIG. 15 is a diagram schematically showing a further additional procedure when spot light is arranged. As already explained, if you can't find an arrangement that does not cause interference with the spot light (indicated by a white star) that is being processed for the arrangement search, first search for the arrangement by substituting the lower spot light. May find an arrangement with less interference.

However, if the arrangement cannot be determined, the calculation unit 214 interferes with the case where the spotlight being processed is arranged in the arrangement of the higher-order spotlight (indicated by a black star). Check to see if this occurs. In this case, it is checked whether or not interference occurs when a predetermined spot light is arranged at a position where the spot light being processed is to be arranged.

Thus, when interference does not occur for both spot lights, the calculation unit 214 determines the arrangement by exchanging the order of the spot lights. In addition, when the spot light being processed cannot be arranged due to interference, the same processing is attempted for the spot light whose arrangement is predetermined at a higher level. Hereinafter, there is a case where the spot light can be arranged without causing interference by repeating the replacement and the search for the arrangement up to the highest-order spot light.

As already described, as the number of spot lights whose arrangement has already been determined increases, the arrangement of new spot lights is restricted. The calculation unit 214 may consider that there is no longer a position where the spot light can be arranged when excessive processing time is required for the spot light arrangement. In such a case, the spot light may be discarded by calculating a reflection angle at which the spot light is projected outside the range of the illumination pattern. Thereby, it is possible to prevent the processing time of the calculation unit 214 from becoming extremely long.

Here, the outside of the range of the illumination pattern may be a region where no optical component is arranged in the imaging optical system 240 of the light source unit 200, for example, the inner surface of a lens barrel that supports the optical component. Further, when there are a plurality of spot lights to be discarded, the spot light to be discarded uniformly or randomly may be distributed over the entire range of the illumination pattern so that the discarded spot light does not form a significant pattern.

As described above, in the above-described procedure, the interference state on the incident surface is evaluated when determining the arrangement of the spot light to be disposed on the incident surface, and based on the evaluation, the reflection mirrors are arranged so that the interference becomes smaller. Each angle is calculated, and it is possible to reduce the occurrence of an unexpected illuminance distribution in the formed illumination pattern. The evaluation of the interference state may be indirect or direct (evaluation of the interference state itself on the incident surface) as described above, and the observation result may be based on simulation. It may be based on.

A series of calculation methods and calculation procedures as described above may be implemented in the calculation unit 214 in advance, or when a part or all of the calculation unit 214 is a general-purpose information processing device, The program for executing the method and procedure may be implemented via some medium or communication line.

In the above description, the calculation unit 214 forms an order in descending order of the intensity of the light source light incident on the reflecting mirror 222 (S201), and the reflection with the high intensity of the incident light source light is performed according to the formed order. Although the mirror 222 has been selected as a processing target (S202), the method is not limited to this. For example, a method of randomly selecting the reflecting mirror 222 may be used.

In the above description, the measurement unit 260 receives the illumination light branched on the spatial light modulator 220 side from the fly-eye lens 310 as an optical integrator, and measures the illumination light image I _3. The configuration may be such that the illumination light image I ₄ or the projection light image I ₅ of the illumination light L that has passed through the fly-eye lens 310 is measured.

In the above embodiment, the spatial light modulator that independently controls the tilt of the mirror elements arranged two-dimensionally is employed. As such a spatial light modulator, for example, European Patent Application No. 779530 is disclosed. , U.S. Pat. No. 6,900,915, U.S. Pat. No. 7,095,546, and the like.

It is also possible to employ a spatial light modulator that independently controls the height of the mirror element as the spatial light modulator. As such a spatial light modulator, for example, the spatial light modulator disclosed in US Pat. No. 5,312,513 and US Pat. No. 6,885,493 can be employed. Furthermore, the above-described spatial light modulator can be modified in accordance with the disclosure of, for example, US Pat. No. 6,891,655 or US Patent Application Publication No. 2005/0095749.

In the above embodiment, the case where the present invention is applied to the scanning stepper has been described. However, the present invention is not limited to this, and the present invention may be applied to a stationary exposure apparatus such as a stepper. The present invention can also be applied to a step-and-stitch reduction projection exposure apparatus that synthesizes a shot area and a shot area.

In addition, as disclosed in, for example, US Pat. No. 6,590,634, US Pat. No. 5,969,441, US Pat. No. 6,208,407, a plurality of wafers. The present invention can also be applied to a multi-stage type exposure apparatus provided with a stage. Further, as disclosed in, for example, US Pat. No. 7,589,822, an exposure including a measurement stage including a measurement member (for example, a reference mark and / or a sensor) separately from the wafer stage. The present invention can also be applied to an apparatus.

In the above embodiment, the case where the exposure apparatus 100 is a dry-type exposure apparatus that exposes the wafer W without using liquid (water) has been described. As disclosed in US Pat. No. 1,420,298, WO 2004/055803, US Pat. No. 6,952,253, and the like, an immersion optical path including illumination light path between the projection optical system and the wafer. The present invention can also be applied to an exposure apparatus that forms a space and exposes the wafer with illumination light through the liquid in the projection optical system and the immersion space.

The projection optical system of the exposure apparatus according to the present invention including the exposure apparatus of the above-described embodiment may be any of a reduction system as well as an equal magnification and an enlargement system, and the projection optical system is not only a refraction system but also a reflection system and Either a catadioptric system may be used, and the projected image may be an inverted image or an erect image.

Further, in the above embodiment, it is also possible to apply a so-called polarization illumination method disclosed in US Patent Application Publication No. 2006/0170901 and US Patent Application Publication No. 2007/0146676.

The light source of the exposure apparatus is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F ₂ laser (output wavelength 157 nm), Ar ₂ laser (output wavelength 126 nm), Kr ₂ laser (output wavelength 146 nm). It is also possible to use a pulse laser light source such as a super high pressure mercury lamp that emits bright lines such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm). A harmonic generator of a YAG laser or the like can also be used. In addition, as disclosed in, for example, US Pat. No. 7,023,610, a single wavelength laser beam in an infrared region or a visible region oscillated from a DFB semiconductor laser or a fiber laser is used as vacuum ultraviolet light. For example, a harmonic that is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

Further, as disclosed in, for example, US Pat. No. 6,611,316, two reticle patterns are synthesized on a wafer via a projection optical system, and 1 on the wafer by one scan exposure. An exposure apparatus that double exposes two shot areas almost simultaneously can be employed as the exposure apparatus 100.

FIG. 16 is a flowchart showing a manufacturing process of a microdevice to which the above generation method can be applied. Note that microdevices include semiconductor devices such as integrated circuits and large-scale integrated circuits, liquid crystal display panels, image sensors such as CCDs and C-MOSs, thin film magnetic heads, micromachines, and the like.

First, the function and performance of the target microdevice are determined, and a structure that realizes the function and performance is designed (for example, circuit design of a semiconductor device). Moreover, the design of the pattern formed in a semiconductor substrate etc. is also included (step S101: design step).

Next, a mask for forming the circuit pattern designed in the above design step is produced (step S102: mask production step). Further, a substrate is manufactured using a material such as silicon, compound semiconductor, glass, ceramics (step S103: substrate manufacturing step).

Subsequently, the circuit board is manufactured by processing the substrate manufactured in the substrate manufacturing step using the mask manufactured in the mask manufacturing step (step S104: substrate processing step). Furthermore, a device is assembled using the substrate processed in the substrate processing step (step S105: device assembly step). The device assembly step includes processes such as dicing, bonding, and packaging (chip encapsulation) as required.

The device assembled as described above is subjected to inspections such as an operation confirmation test and a durability test (step S106: inspection step). The microdevice thus inspected is shipped as a product.

FIG. 17 is a flowchart showing the contents of the substrate processing step. That is, FIG. 17 shows details of step S104 shown in FIG. In the substrate processing step, a circuit is formed on the substrate by lithography, for example.

Steps S111 to S114 described below form a pretreatment process of the substrate processing step. The processing in each step is not necessarily essential, and is appropriately selected according to the specifications of the microdevice to be manufactured.

In the pretreatment process, first, the surface of the substrate is oxidized to form an oxide film (step S111: oxidation step). Next, an insulating film is formed on the surface of the substrate (step S112: CVD step). Hereinafter, for example, electrodes are formed by vapor deposition (step S113: electrode formation step), and ions are also implanted into the substrate (step S114: ion implantation step).

Next, a post-processing step in the substrate processing step is executed. In the post-processing step, first, a photosensitive material is applied to the substrate (step S115: resist formation step). Next, the photosensitive material is exposed by the exposure apparatus 100 with an exposure pattern corresponding to the target pattern (step S116: exposure step). Next, the exposed photosensitive material is developed to form a mask layer having a pattern on the surface of the substrate (step S117: development step).

Next, the region exposed from the mask layer is removed by etching (step S118: etching step). Further, the already used mask layer is removed (step S119: resist removal step). In this way, a circuit is formed on the surface of the substrate, but the pre-processing step and the post-processing step are repeatedly executed, and a multi-layered circuit is formed on the substrate.

In the above embodiment, the object on which the pattern is to be formed (the object to be exposed to which the energy beam is irradiated) is not limited to the wafer, but may be another object such as a glass plate, a ceramic substrate, a film member, or a mask blank. good.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

It should be noted that the order of execution of procedures, steps, stages, etc. in the operation and method of the apparatus shown in the claims, the specification, and the drawings is clearly indicated as `` before '', `` prior '', etc. Alternatively, it can be realized in any order except when the output of the previous stage is used in the subsequent stage. Even if “first”, “next”, and the like are used for convenience in the claims, the description, and the drawings, it does not necessarily mean that execution in this order is essential.

100 exposure apparatus, 110 light source, 200 light source unit, 210 control unit, 212 drive unit, 214 calculation unit, 216 medium, 220 spatial light modulator, 222 reflector, 223, 225 electrode, 224 substrate, 226 flexure, 230 prism, 232, 234, reflective surface, 240, 340, imaging optical system, 250 beam splitter, 260 measuring unit, 300 illumination optical system, 312 entrance surface, 310 fly-eye lens, 320 condenser optical system, 330 field stop, 400 projection optical system, 410 exposure mask, 420 mask stage, 430 aperture stop, 510 substrate, 520 substrate stage

Claims

An illumination device that illuminates an illuminated surface with light source light incident from a light source,
Spatial light modulation that has a plurality of reflecting mirrors that reflect the light source light at individually set reflection angles and emit a plurality of reflected lights, and project the plurality of reflected lights onto a projection surface to form an illumination pattern Elements,
Under the condition of making the mutual interference of the plurality of reflected lights smaller, a calculation unit that calculates the reflection angle of each of the plurality of reflecting mirrors;
A driving unit configured to drive the plurality of reflecting mirrors and set the reflection angle calculated by the calculating unit to each of the plurality of reflecting mirrors.
The calculation unit includes:
Based on the coherence of the light source light,
The interference generation distance between the reflectors where the plurality of reflected lights interfere with each other, and the interference generation interval between the plurality of reflected lights on the projection surface,
2. The reflection angle at which the reflected light of the plurality of reflecting mirrors having a distance shorter than the interference generation distance is projected on a region separated from the interference generation interval on the projection surface is calculated. Lighting device.
The calculation unit sequentially calculates the reflection angle for each of the plurality of reflecting mirrors, and calculates the reflection angle set for the one reflecting mirror when the reflecting angle cannot be calculated for one reflecting mirror. The lighting device according to claim 1 or 2, comprising a condition.
The said calculating part considers that the said reflection angle cannot be calculated when the processing time concerning calculation of the said reflection angle about one of these reflective mirrors exceeds a predetermined threshold value. The lighting device according to any one of the above.
The calculation unit, when the reflection angle cannot be calculated for one of the plurality of reflection mirrors, discards the calculated reflection angle for the other reflection mirror of the plurality of reflection mirrors, The reflection angle of the one reflecting mirror and the other reflecting mirror is calculated on the condition that interference generated in the reflected light of the one reflecting mirror and the reflected light of the other reflecting mirror is totally reduced. The lighting device according to any one of claims 1 to 4.
When the reflection angle cannot be calculated for one of the plurality of reflection mirrors, the calculation unit calculates a reflection angle for projecting reflected light outside the effective range of the projection surface for the reflection mirror. The lighting device according to any one of claims 1 to 5.
The illumination according to any one of claims 1 to 6, wherein the calculation unit sequentially calculates the reflection angle from a reflecting mirror into which light source light with higher illuminance is incident, among the plurality of reflecting mirrors. apparatus.
The projection surface is an illumination pupil plane of the illumination device, and the irradiated surface is Koehler illuminated with light from an illumination pattern formed on the illumination pupil plane. The illumination device according to any one of the above.
An exposure apparatus comprising the illumination device according to any one of claims 1 to 8.
Spatial light that has a plurality of reflecting mirrors that reflect incident light source light at individually set reflection angles and emit a plurality of reflected lights, and forms an illumination pattern by projecting the plurality of reflected lights onto a projection surface A modulation element;
A calculation unit for calculating a reflection angle set for each of the plurality of reflecting mirrors;
A control program that drives the plurality of reflecting mirrors and controls an illuminating device including a driving unit that sets the reflection angle calculated by the calculating unit to each of the plurality of reflecting mirrors,
The program which calculates the said reflection angle of each of these reflective mirrors on the conditions which make mutual interference of these reflective lights which form the said illumination pattern smaller.
Under the condition that the interference between the plurality of reflected lights forming the illumination pattern is made smaller, a calculation stage for calculating the reflection angle of each of the plurality of reflecting mirrors;
A driving step of driving the plurality of reflecting mirrors and setting the reflection angle calculated in the calculating step to each of the plurality of reflecting mirrors;
An illumination method comprising: forming an illumination pattern by reflecting incident light source light at the reflection angles set individually to emit a plurality of reflected lights and projecting the plurality of reflected lights onto a projection surface.
An exposure method for illuminating a projection object using the illumination method according to claim 11, and forming an image of the projection object on the object by passing light from the illuminated projection object through a projection optical system.
13. The exposure method according to claim 12, wherein the projection surface is a position optically conjugate with a position of an aperture stop of the projection optical system or a vicinity of the conjugate position.
Forming a pattern on an object using the exposure method according to claim 12 or 13;
Developing the object on which the pattern is formed, and forming a mask layer having a shape corresponding to the pattern on the surface of the object;
Processing the surface of the object through the mask layer.