JP6871030B2 - Projection exposure equipment - Google Patents

Description

The present invention provides a height detection (measurement) means for measuring the height and inclination of the surface of a substrate (wafer, work) and an exposure area (a range in which a reticle pattern is projected on the surface (focal surface) of the substrate). The present invention relates to a projection exposure apparatus including a variable aperture (aperture blade) mechanism for limiting.

An exposure apparatus using a projection optical system can expose a fine pattern by exposing the focal plane of the projection optical system in a state where the surface of the substrate is exactly aligned with each other. Therefore, the projection exposure apparatus generally controls the height and inclination of the substrate by the height detecting means for measuring the height (position in the Z direction and the optical axis direction) and the inclination of the substrate surface and the output of the height detecting means. It is equipped with a control means.

Conventionally, an air microgauge, a laser displacement meter, a magnetic sensor and the like are known as height detecting means. In particular, as is well known, the air microgauge measures the distance to the substrate by ejecting gas from the tip of the probe, so the height is stable regardless of the optical characteristics of the photoresist applied to the substrate. Is suitable as a height detecting means and is generally used (see the air sensor nozzle (21) of Patent Document 1 and the sensor (210) of Patent Document 2).

On the other hand, it is known that stray light caused by lens reflection of the projection optical system, that is, flare, irradiates the outside of the exposed area of the substrate with light that is not involved in imaging, and this flare causes uneven exposure and resolution. It is common practice to provide a variable aperture mechanism to limit the exposure area to block flare (auxiliary aperture mechanism (11) of Patent Document 3, shutter (26a, of Patent Document 4)). 26b)).

Japanese Patent Application Laid-Open No. 61-196532 JP-A-2007-49165 Japanese Patent Application Laid-Open No. 4-77744 JP-A-11-121330

Patent Document 1 discloses the idea of detecting the inclination of the entire substrate by installing the air microprobes at intervals, but it is not possible to detect the inclination of a narrow range of the exposure region. In step exposure, since a large number of exposure areas are set on a single substrate and exposed in order, even if the inclination of the entire substrate is detected, it is not possible to accurately correspond to the inclination of each exposure area. Further, Patent Document 2 proposes that the air microprobe is provided close to the exposure region (not only in the Z direction but also in the XY direction) to improve the accuracy of the substrate in the Z direction with respect to the exposure region. However, the exposure area is not limited by the variable aperture mechanism, and the relationship between the variable aperture mechanism and the air microprobe is not disclosed. In any case, in the conventional apparatus, it is not possible to arrange at least three air microprobes in the vicinity of the variable aperture mechanism that limits the exposure area.

Purpose of the invention

The present invention does not detect the height position and inclination of the entire substrate, but detects the height position and inclination of the exposure region, which is much smaller than the planar size of the entire substrate, and detects the height position and inclination of the exposure region. Based on the idea that more precise exposure control is possible by controlling the height and tilt, at least three air microprobes are placed close to the exposure area in the vicinity of the variable aperture mechanism that limits the exposure area. The purpose is to obtain a projection exposure device capable of this.

The present invention is a projection exposure apparatus using two pairs of aperture blades (variable aperture mechanism) that are movement-controlled in two orthogonal directions as a variable aperture mechanism and determine a (rectangular) exposure area by each aperture edge. As a result of considering the arrangement position of the air microprobe, it is possible to arrange at least three air microprobes close to the exposure region.

In the projection exposure apparatus of the present invention, at least three probes of the air microgauge for detecting the height position of the surface (exposed surface) of the substrate and movement control in the directions orthogonal to each other are controlled by the respective aperture edges. In a projection exposure apparatus having two pairs of aperture blades that limit the exposure area of the projection optical system, at least one of the paired aperture blades of any one of the two pairs of aperture blades has at least three of the above probes. It is characterized in that it is arranged so as to advance and retreat between the first and second probes inside.

It is preferable that the third probe among the at least three probes is arranged on the opposite side of the first and second probes with the exposure region interposed therebetween.

The d flax Ikurogeji has a two pairs probe, the two pairs of probes on both sides of the moving direction of the aperture blade which forms one of the pairs of apertures blades of the two pairs, is separated into its moving direction It is preferable that the two pairs of probes are arranged so that the other pair of aperture blades move forward and backward.

At least three air microgauge probes can be placed on a single air microgauge block with an exposure aperture.

All the air microgauge probes are in a circle with a radius of twice the maximum distance of the inner wall of the exposure aperture from the planar center of the exposure aperture, preferably 1.5 times, more preferably 1.25 times. Place inside.

Each of the aperture blades includes a straight-ahead actuator, and the probe can be positioned between the straight-ahead actuator and the exposure area.

The positions of the advance / retreat planes of the two pairs of aperture blades in the optical axis direction are different, and it is practical that the tip of the probe is located on the exposed surface side of the advance / retreat planes of the two pairs of aperture blades. ..

As the projection optical system, a Dyson optical system can be used.

In another aspect, the projection exposure apparatus of the present invention uses at least two probes of an air microgauge for detecting the height position of the surface (exposed surface) of the substrate and an aperture edge to provide an exposed area by the projection optical system. In a projection exposure apparatus having at least one moveable aperture blade that limits, one of the aperture blades is arranged to move back and forth between the two probes.

According to the projection exposure apparatus of the present invention, at least three air microprobes are arranged in the vicinity of an exposure region determined by two pairs of aperture blades (variable aperture mechanisms) whose movements are controlled in two orthogonal directions. Can be done. Therefore, it is possible to perform exposure for each exposure region while adjusting the height and inclination of the exposure region according to the height and inclination of the small exposure region on the substrate, and at the same time prevent the occurrence of exposure defects due to flare.

It is a side perspective view of the whole projection exposure apparatus which shows one Embodiment of the projection exposure apparatus by this invention. It is an enlarged side view of the aperture unit in the projection exposure apparatus of FIG. It is a bottom view which shows the minimum exposure area by the variable aperture mechanism along line III-III of FIG. It is a bottom view which shows the maximum exposure area by the variable aperture mechanism along line III-III of FIG. It is the bottom view of the air micro gauge block alone. It is a top view which shows the setting example of a plurality (many) exposure areas on one substrate. It is a bottom view corresponding to FIG. 3B which shows another embodiment of the projection exposure apparatus according to this invention.

An embodiment of the projection exposure apparatus according to the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a projection exposure apparatus 10 provided with a projection optical system known as a Dyson type. The projection exposure apparatus 10 shown in FIG. 1 is known by, for example, Patent Document 5, and projects a predetermined pattern drawn on a photomask such as a reticle R on the surface (exposed surface) of a substrate SB such as a silicon wafer. It is an exposure device. The substrate SB is placed on the substrate stage 12 provided on the gantry 11.

The substrate stage 12 tilts with respect to the substrate mounting portion 12W on which the substrate SB is placed and held by means such as vacuum suction and the emission optical axis O of the projection exposure apparatus 10 in order from the top of FIG. A well-known mechanism having a θ moving portion (tilting portion) 12θ, a Z moving portion 12Z moving in a direction parallel to the emitted optical axis O, and an XY moving portion 12XY moving on an XY plane orthogonal to the emitted optical axis O. Is.

On the surface (exposed surface) of the substrate SB, the pattern formed on the reticle R is projected via the projection optical system 15 by using the light from the illumination optical system 13. The reticle R is held by a reticle stage 14 that can move in a direction perpendicular to and parallel to the optical axis 13O of the illumination optical system 13 by using a vacuum suction means or the like.

The illumination optical system 13 irradiates the reticle R with light from the light source 16 using a short arc clamp or the like as uniform parallel light through the flyeye integrator 17, collimated lens 18, etc., and transmits the irradiated parallel light through the reticle R. Then, it leads to the projection optical system 15. The light emitted from the light source 16 includes g-line (wavelength 436 nm), h-line (405 nm), and i-line (365 nm), and the illumination optical system 13 includes a wavelength filter and a dichroic mirror (not shown). Of the light emitted from the light source 16 using the above, only the light having a predetermined wavelength is supplied to the projection optical system 15. Further, the amount of light is controlled by a shutter or the like (not shown).

The projection optical system 15 is composed of a concave mirror (reflection optical element) M0 having condensing power and a refraction optical system 19 composed of a plurality of lenses (refractive optical elements). The refractive optics 19 is a first plane mirror M1 that deflects the exposure light from the reticle (object surface) R toward the refractive optics 19, and deflects the exposure light from the refractive optics 19 toward the substrate SB. A second plane mirror M2 that emits light on the emission optical axis O is included. The exposure light transmitted through the reticle R is reflected by the first plane mirror M1 toward the refraction optical system 19, and the exposure light passing through the refraction optical system 19 is reflected by the concave mirror M0 and is incident on the refraction optical system 19 again. After that, the exposure light is reflected by the second plane mirror M2 and projected on the emission optical axis O in the direction of the substrate stage 12, and the reticle R is formed on the surface (exposed surface) of the substrate SB corresponding to the image plane of the projection optical system 15. Image image.

In the exposure light emitting portion of the projection optical system 15, the aperture unit 20 is fixed to the base portion of the second plane mirror M2 and the projection optical system lens barrel via a frame (not shown) or the like (FIG. 1). As shown in FIG. 2, the aperture unit 20 has a unit base 21 and an air microgauge block 31 in this order from the projection optical system 15 side. The unit base 21 is formed with a flat rectangular opening (aperture for passing exposure light) 22 located on the emission optical axis O of the projection optical system 15 and long in the X direction.

The air microgauge block 31 is formed with a flat rectangular exposure opening 32 having a diameter smaller than that of the opening 22 of the unit base 21 and long in the X direction. A thin edge 32a is formed at the upper end of the exposure opening 32 in the Z direction, and a marker exposure recess 32b is formed at both ends of the exposure opening 32 in the X direction facing the Y direction. In the following description, the direction parallel to the emission light axis O passing through the plane center of the exposure opening 32 is the Z axis (direction), orthogonal to Z, and the direction parallel to the lateral direction and the longitudinal direction of the exposure opening 32 is the X axis. Assume a Cartesian coordinate system XYZ with (direction) and Y-axis (direction).

In the air microgauge block 31, three air microprobes (hereinafter, simply probes) 33 (33A, 33B, 33C) of the air microgauge are formed (attached) around the exposure opening 32. The direction of the probe 33 is set so that the air (fluid) discharged from the probe 33 is correctly oriented in the direction parallel to the Z axis (see FIG. 2). A pipe 33a to the probe 33 is formed in the air micro gauge block 31, and the pipe 33a is connected to the air micro gauge (air micro measuring unit) 34A in the control means 34 (FIG. 4) via the external pipe 33b. It is connected. The air microgauge 34A is connected to a gas source (not shown).

The air microgauge 34A ejects pressure-controlled air (fluid) from all probes 33, and detects the distance from the substrate SB by the pressure change. By detecting the pressure of the air (fluid) ejected from the three probes 33, the distance to the substrate SB at the position of each probe 33 and the inclination of the plane defined by the three probes 33 are detected. be able to.

As shown in FIG. 4, the control means 34 also raises and lowers the substrate mounting portion 12W via the Z moving portion 12Z of the substrate stage 12 according to the height of the substrate SB detected by the output of the air microgauge 34A. The Z drive system 34Z, the θ drive system 34θ that tilts the substrate mounting portion 12W via the θ moving portion 12θ according to the inclination of the surface (exposed surface) of the substrate SB, and the XY of the substrate SB via the XY moving portion 12XY. An XY drive system 34XY that controls a position in a plane is provided.

The first probe 33A and the second probe 33B, which are two of the three probes 33, are arranged at symmetrical positions with respect to the X axis on a straight line in the Y direction parallel to the longitudinal direction of the exposure opening 32. The remaining one, the third probe 33C, is located on the opposite side of the exposure opening 32 of the first probe 33A and the second probe 33B, and is positioned with the first probe 33A and the second probe 33B. , Are arranged on the X-axis so as to form a regular triangle located in a plane parallel to the XY plane. In this embodiment, the height and inclination of the entire substrate SB are not detected, but the height of the surface (exposed surface) of the substrate SB is determined for each exposure region set on the substrate SB (surface, exposed surface). Detect tilt. Therefore, three probes 33 (33A, 33B, and 33C) are arranged in the vicinity of the periphery of the exposure aperture 32 having a size substantially equal to the maximum exposure area (slightly larger than the maximum exposure area) on the substrate SB. There is. In order to detect the height and inclination of the exposure area EA, for example, a radius twice, preferably 1.5 times, a radius of twice the maximum distance of the inner wall of the exposure aperture 32 from the planar center of the exposure aperture 32, more preferably. All probes 33 are placed in a circle with a radius of 1.25 times. In the embodiment shown in FIG. 4, three probes 33A, 33B, and 33C are arranged in a circle drawn with a radius of 1.25 times the maximum distance. The larger the radius of the circle (distance from the center of the exposure aperture 32), the higher the accuracy of tilt detection. However, when the radius of the circle exceeds twice the maximum distance, the probes 33A, 33B, and 33C are used as the exposure area EA. You will not be able to get close enough.

The unit base 21 described above includes a pair of fixed portions 35 located on opposite sides of the pair of probes 33A and 33B with the exposure opening 32 interposed therebetween and arranged in the X direction, and Y on the opposite side of the probe 33C with the exposure aperture 32 interposed therebetween. It is fixed to the unit base 21 by one fixing portion 35 located on the shaft.

Two pairs of variable aperture mechanisms 40 and 50 are provided on the unit base 21 to limit the exposure aperture 32 of the air microgauge block 31 to limit the exposure area EA. The variable aperture mechanism 40 has a pair of X aperture blades (X shading plates) 41 that advance and retreat in the X direction so as to open and close the exposure aperture 32, and a linear actuator 42 thereof. The variable aperture mechanism 50 is exposed. It has a pair of Y aperture blades (Y shading plates) 51 that move forward and backward in the Y direction so as to open and close the opening 32, and a linear actuator 52 thereof. The X aperture blade 41 and the Y aperture blade 51 have different height positions (advance / retreat plane, height position in the direction parallel to the Z axis) so that they do not interfere with each other (in the illustrated example, the height position is different). As shown in FIG. 2, the Y aperture blade 51 is higher).

The edges of the X aperture blade 41 and the Y aperture blade 51 on the exposure aperture 32 side form the aperture edges 41d and 51d parallel to the Y direction and the X direction, respectively, and the exposure area is formed by these aperture edges 41d and 51d. An EA (hatched in FIGS. 3A and 3B) is formed. The size of the exposure region EA can be adjusted (controlled) by advancing and retreating the X aperture blade 41 and the Y aperture blade 51 by the linear actuators 42 and 52. FIG. 3A shows the minimum exposure region EA, and FIG. 3B shows a state in which the marker exposure recess 32b of the exposure aperture 32 is exposed by the pair of Y aperture blades 51 (maximum exposure region EA).

Looking at the positional relationship of the probe 33, the X aperture blade 41, and the Y aperture blade 51 in a plane (when viewed from a direction parallel to the Z axis), one of the pair of variable aperture mechanisms 40 and 50 is a variable aperture. A pair of probes 33A and 33B) among the three probes 33 are arranged on one side of the pair of Y aperture blades 51 of the mechanism 50 so as to be separated from each other in the advancing / retreating direction, and the pair of probes 33A). One X aperture blade 41 of the other variable aperture mechanism 40 is arranged so as to advance and retreat between the and 33B (across a virtual straight line connecting the probes 33A and 33B). By arranging the probe 33, the X aperture blade 41, and the Y aperture blade 51 in this way, the height and inclination of the exposure region EA, which is smaller than the area of the substrate SB, are detected, and the height and inclination are adjusted. , Individual exposure area EA can be correctly exposed.

FIG. 5 shows an example of a small area exposure area EA and step exposure set on the substrate SB. In FIG. 5, the exposure region EA formed by the variable aperture mechanism 40 (X aperture blade 41) and the variable aperture mechanism 50 (Y aperture blade 51) of the aperture unit 20 is shown with solid line hatching, and the aperture unit 20 is shown. On the other hand, the contours of a large number of exposure regions EA that are moved and exposed in the XY plane by the XY moving unit 12XY are shown by a two-dot chain line.

According to the projection exposure apparatus 10 according to the present embodiment, since the periphery of the exposure region EA on the substrate SB is covered with the X and Y aperture blades 41 and 51 of the variable aperture mechanisms 40 and 50, the light is emitted from the projection optical system 15. Of the exposed light, the unnecessary light that does not contribute to the exposure is surely shielded by the X and Y aperture blades 41 and 51 and does not reach the substrate SB. Further, this effect of blocking unnecessary light can also be obtained in the Dyson optical system known as a catadioptric system in which aberrations are canceled by the reciprocating light flux.

The state of FIG. 3B shows a state in which the marker exposure recess 32b of the exposure opening 32 is exposed by the Y aperture blade 51 of the variable aperture mechanism 50. In the actual step exposure, in this state, the alignment mark (not shown) formed on the substrate SB is observed to determine the exposure area, and then the Y aperture blade 51 (X aperture blade 41) is determined. Move to the position corresponding to the size of the area.

In principle, the air microgauge 34A can detect the height and inclination of the exposure region EA of the substrate SB by the three probes 33 as in the above-described embodiment. However, it is also possible to use four or more probes 33 (or arrange four or more probes 33 and use the outputs of three probes 33 among them). FIG. 6 shows another embodiment of the projection exposure apparatus according to the present invention in which two pairs of four probes 33 are arranged.

In this embodiment, two probes 33 (33A and 33B, and 33C and 33D) are arranged on both sides of the pair of Y aperture blades 51 of the variable aperture mechanism 50 so as to be separated from each other in the advancing / retreating direction. Further, a pair of X aperture blades 41 of the variable aperture mechanism 40 are arranged so as to advance and retreat across a virtual straight line connecting the probes 33 (33A and 33B, and 33C and 33D). In other words, the two probes 33A and 33B and the two probes 33C and 33D are arranged symmetrically with respect to the Y axis.
As described above, the outputs of the two pairs (4) of the probes 33 (33A and 33B, and 33C and 33D) may be all or selectively three.
Instead of the air microprobe, a sensor probe for distance measurement such as a laser displacement meter or a magnetic sensor may be used.

SB Substrate 10 Projection exposure device 11 Stand 12 Substrate stage 12Z Z Moving part 12XY XY Moving part 12W Board mounting part 12θ θ Moving part 13 Illumination optical system 14 Reticle stage 15 Projection optical system 16 Light source 17 Flyeye integrator 18 Collimating lens 19 Refraction Optical system 20 Aperture unit 21 Unit base 22 Opening 31 Air micro gauge block 32 Exposure opening 32a Thin-walled edge 32b Marker exposed recess 33b External piping 33 Air microprobe (air microgauge, probe)
33A, 33B, 33C air microprobes (first, second, third probes)
33a Piping 34 Control means 34A Air micro gauge 34XY XY Drive system 34Z Z Drive system 34 θ θ Drive system 35 Fixed boss 40 Variable aperture mechanism 41 X Aperture blade (pair of aperture blades)
41d Aperture edge 42 Linear actuator 50 Variable aperture mechanism 51 Y aperture blade (pair of aperture blades)
51d Aperture Edge 52 Linear Actuator EA Exposure Area

Claims (9)

With at least three probes of the air microgauge to detect the height position of the exposed surface,
In a projection exposure apparatus having two pairs of aperture blades whose movements are controlled in directions orthogonal to each other and whose respective aperture edges limit the exposure area by the projection optical system.
At least one of the paired aperture blades of any one of the two pairs of aperture blades is arranged so as to advance and retreat between the first and second probes in the at least three probes. Projection exposure equipment. In the projection exposure apparatus according to claim 1, the third probe among the at least three probes is arranged on the opposite side of the first and second probes with the exposure region interposed therebetween. .. In the projection exposure apparatus according to claim 1, wherein said error flax Ikurogeji has a two pairs probe, the two pairs of probes, the moving direction of the aperture blade which forms one of the pairs of apertures blades of the two pairs A projection exposure apparatus which is arranged on both sides so as to be separated from each other in the advancing / retreating direction, and the aperture blades forming the other pair are respectively arranged between the two pairs of probes so as to advance / retreat. In the projection exposure apparatus according to any one of claims 1 to 3, at least three air microgauge probes are arranged on a single air microgauge block having an exposure aperture. In the projection exposure apparatus according to claim 4, all the probes of the air microgauge are arranged in a circle having a radius twice the maximum distance of the inner wall of the exposure aperture from the planar center of the exposure aperture. apparatus. In the projection exposure apparatus according to any one of claims 1 to 5, each of the aperture blades includes a straight-ahead actuator, and the probe is a projection exposure apparatus located between the straight-ahead actuator and the exposure region. In the projection exposure apparatus according to any one of claims 1 to 6, the positions of the advance / retreat planes of the two pairs of aperture blades in the optical axis direction are different, and the tips of the probes are of the two pairs of aperture blades. A projection exposure apparatus located on the surface to be exposed side from the advance / retreat plane. The projection exposure apparatus according to any one of claims 1 to 7, wherein the projection optical system is a Dyson optical system. With at least two probes of the air microgauge to detect the height position of the exposed surface,
In a projection exposure apparatus having at least one moveable aperture blade that limits the exposure area of the projection optics by an aperture edge.
A projection exposure apparatus, characterized in that one of the aperture blades is arranged so as to move back and forth between the two probes.

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