JP2008262112A - Optical diaphragm apparatus, projection optical system, aligner, and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical diaphragm apparatus where positioning precision in the aperture part of a diaphragm in each NA value is improved, using a simple constitution. <P>SOLUTION: Disclosed is an optical diaphragm apparatus comprising a circular base plate; a plurality of aperture blades, each being provided with a pin member and a cam member, and rotatably supported to the base plate by the pin member; and a circular cam disk with a cam groove, into which the cam member is movably inserted, and rotating the aperture blades, wherein one region of the plurality of aperture blades is mutually overlapped, and by mutually sliding the plurality of aperture blades, a diaphragm aperture part, having the prescribed number of apertures, is formed. The pin member and the cam member are provided, with the light-shielding region of the aperture blades forming the diaphragm aperture part and blocking the light in-between. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an optical diaphragm apparatus that is disposed in an optical system mounted on an optical apparatus and forms a diaphragm aperture having a predetermined numerical aperture.

In general, in a lithography process for manufacturing a device such as a semiconductor element, a pattern formed on a mask such as a photomask or a reticle is applied to a wafer coated with a photosensitive material such as a resist or a glass plate via a projection optical system. An exposure apparatus that transfers onto a substrate is used.
As this type of exposure apparatus, a static exposure type exposure apparatus such as a stepper and a scanning type exposure apparatus such as a scanning stepper are mainly used.
In recent years, in devices, particularly semiconductor elements, circuit patterns have been remarkably miniaturized, and simultaneously with the development of resist processes, there has been a great demand for higher resolution for exposure apparatuses.
In order to meet this demand, in the exposure apparatus, development of high resolution is being promoted by a method of using exposure light having a shorter wavelength and increasing the numerical aperture of the projection optical system.
Recently, along with the progress of design / manufacturing technology and the introduction of immersion technology, an exposure apparatus equipped with a projection optical system having a higher NA, for example, NA = 1.00 has been developed.
Further, it is necessary to ensure the depth of focus of the projection optical system while improving the resolution.
Since the depth of focus decreases as the NA increases, in an actual process, conditions for optimizing the NA for improving the resolving power are secured while ensuring the depth of focus.
For this reason, an ordinary projection optical system incorporates an optical aperture device that can change the NA substantially in a stepless manner so that the NA can be selected.

Conventionally, an optical aperture device for making NA variable is proposed in, for example, Japanese Patent Application Laid-Open No. 2003-307763 (Patent Document 1).
In this conventional optical diaphragm apparatus, an iris diaphragm mechanism is used in which a plurality of diaphragm blades are overlapped with each other, and each diaphragm blade is rotated while sliding to change the aperture diameter.
8 and 9, each component of the iris diaphragm mechanism is shown expanded in the optical axis direction, and the base plate 7 surrounding the optical path of the exposure light and the base plate 7 are overlapped in the circumferential direction. A plurality of aperture blades 6 are arranged, and an aperture opening 20 is formed.
A pin member 8 serving as the center of rotation is provided on each side of the diaphragm blade 6 and a cam member 9 serving as a guide is provided on the other side.
The cam disk 10 disposed on the aperture blade 6 has a cam groove 10b into which the cam member 9 protruding from each aperture blade 6 is fitted, and rotates reciprocally as indicated by an arrow.
By this reciprocating rotation, all the diaphragm blades 6 are simultaneously slid around the pin member 8 serving as the rotation center by a predetermined angle via the cam member 9 according to the rotation amount, as indicated by an arrow, The numerical aperture of the part 20 is configured to be adjusted.

However, the exposure apparatus is required to improve the resolving power, and the NA of the projection optical system is required to improve the roundness of the aperture and the positioning accuracy at each NA value.
The roundness of the aperture opening at each NA value has been improved by a method of increasing the number of aperture blades.
Further, as proposed in Japanese Patent Application Laid-Open No. 2003-307763 (Patent Document 1), Japanese Patent Application Laid-Open No. 5-11306 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2002-99022 (Patent Document 3), Improvement has been achieved by forming the side shape with a predetermined curve or straight line.
Japanese Patent Laid-Open No. 2003-307763 JP-A-5-11306 JP 2002-99022 A

The diaphragm blade 6 constituting the conventional optical diaphragm device disclosed in Japanese Patent Application Laid-Open No. 2003-307763 (Patent Document 1) shown in FIGS. 8 and 9 includes a pin member 8 serving as a rotation center of the diaphragm blade 6 and a cam disk 10. And a cam member 9 for rotating the diaphragm blade 6 by the cam groove 10a.
Furthermore, it has the light-shielding area | region 11 which shields a light ray, and forms the aperture opening part 20. FIG.
For this reason, due to the processing error of the cam groove 10b of the cam disk 10 or the positioning error 12 of the diaphragm blade 6 on the cam member 9 generated due to the fitting gap between the cam groove 10b of the cam disk 10 and the cam member 9 of the diaphragm blade 6 or the like. The positioning error 13 in the light shielding region 11 that actually shields the light beam is larger.
For this reason, even if the roundness of the aperture 20 is improved at each NA value, the aperture diameter cannot satisfy a predetermined size and accuracy, and a slight difference in resolution occurs.
Accordingly, an object of the present invention is to provide an optical diaphragm device that improves the positioning accuracy of the diaphragm aperture at each NA value with a simple configuration.

In order to achieve the above object, an optical diaphragm apparatus of the present invention includes an annular base plate, a plurality of diaphragm blades provided with a pin member and a cam member, and rotatably supported by the pin member on the base plate. An annular cam disk having a cam groove in which the cam member is movably inserted and rotates the diaphragm blades, and one region of the plurality of diaphragm blades overlaps each other, and the plurality of diaphragm blades are An optical diaphragm apparatus that forms a diaphragm aperture having a predetermined numerical aperture by sliding each other, and sandwiches a light shielding region of the diaphragm blade that forms the diaphragm aperture and shields light rays, A cam member is provided.

According to the optical diaphragm device of the present invention, the pin member and the cam member are provided with a light shielding area of the diaphragm blade that forms the diaphragm opening and shields the light beam.
In the conventional optical aperture device, as shown in FIG. 9, the cam member 9 moves in the cam groove 10 b of the cam disk 10 with the pin member 8 as the rotation center.
Since the light shielding region 11 of the diaphragm blade 6 is located farther than the cam member 9 with respect to the pin member 8, the positioning error 13 of the light shielding region 11 of the diaphragm blade 6 is reduced more than the positioning error 12 of the cam member 9. The
According to the optical diaphragm device of the present invention, as shown in FIG. 4, the pin member 8 and the cam member 9 are provided with the diaphragm aperture 20 formed and the light shielding region 11 of the diaphragm blade 6 that shields the light beam interposed therebetween.
Since the light shielding region 11 of the diaphragm blade 6 is located closer to the pin member 8 than the cam member 9, the positioning error 13 of the light shielding region 11 of the diaphragm blade 6 is reduced more than the positioning error 12 of the cam member 9. The
For this reason, it is possible to reduce the positioning error in the light shielding region 11 of the diaphragm blade 6, to suppress the occurrence of a subtle difference in resolving power, and the positioning accuracy of the diaphragm opening 20 at each NA value with a simple configuration. Improve.

  Embodiments of the present invention will be described below with reference to the drawings.

First, an exposure apparatus having a projection optical system having an optical aperture device according to an embodiment of the present invention will be described with reference to the schematic block diagram of FIG.
This exposure apparatus synchronously moves a reticle R as a mask and a wafer W as a substrate coated with a photosensitive agent in a unified direction (here, the Y-axis direction which is the horizontal direction in FIG. 1).
Further, the circuit pattern formed on the reticle R is transferred to each shot area on the wafer W through the projection optical system PO while performing this synchronous movement.
That is, this exposure apparatus is a step-and-scan scanning exposure apparatus, so-called scanning stepper.
The reticle R is held by a reticle chuck 1. The wafer W is supported on the wafer stage 3 having precise positioning performance via the wafer chuck 2.
The projection optical system PO projects and exposes the pattern on the reticle R surface illuminated with the exposure light from the illumination optical system IL onto the wafer surface at a predetermined magnification (for example, 1/4 or 1/5).
The optical aperture device 4 is disposed in the vicinity of the pupil position of the projection optical system PO, and the surface plate 5 supports the projection optical system PO.

Next, an optical aperture device according to a first embodiment of the present invention will be described with reference to the configuration diagrams of FIGS.
The base plate 7 is formed in an annular shape.
The plurality of diaphragm blades 6 are provided with a pin member 8 and a cam member 9, and are rotatably supported on the base plate 7 by the pin member 8.
The annular cam disk 10 has a cam groove 10a in which the cam member 9 is movably inserted and rotates the diaphragm blade 6.
Further, the aperture openings 20 having a predetermined numerical aperture are formed by overlapping one region of the plurality of aperture blades 6 and sliding the plurality of aperture blades 6 with each other.
Further, the pin member 8 and the cam member 9 are provided across the light shielding region 11 of the diaphragm blade 6 that forms the aperture opening 20 and shields the light beam.
For this reason, since the light shielding area 11 of the diaphragm blade 6 is located closer to the pin member 8 than the cam member 9, the positioning error 13 of the light shielding area 11 of the diaphragm blade 6 is more than the positioning error 12 of the cam member 9. Is reduced.
For this reason, it is possible to reduce the positioning error in the light shielding region 11 of the diaphragm blade 6, to suppress the occurrence of a subtle difference in resolving power, and the positioning accuracy of the diaphragm opening 20 at each NA value with a simple configuration. Improve.
In the first embodiment, a plurality of diaphragm blades 6 having the same shape are used as the diaphragm blades 6.
Each of the diaphragm blades 6 is disposed on the base plate 7 and includes a pin member 8 that is a center of rotation planted on the diaphragm blades 6 and a cam member 9 that sets the rotation angle of the diaphragm blades 6.
The cam disk 10 is provided with cam grooves 10 a having the same number and equal distribution as the diaphragm blades 6 so as to rotate the diaphragm blades 6 by the cam members 9 of the diaphragm blades 6, and is configured to be rotatable about the optical axis 21.
Further, the optical diaphragm apparatus according to the first embodiment rotates the cam disk 10 by a predetermined rotation amount by a driving force from a motor (not shown) disposed in the vicinity of the optical diaphragm apparatus via the cam groove 10a of the cam disk 10. Thus, the aperture blade 6 is positioned at a predetermined position.
For example, the aperture blade 6 has an arcuate contour on the inner diameter side, and the curvature of the inner arc is substantially the same as the aperture diameter corresponding to the maximum numerical aperture required for the projection optical system PO.
When the aperture diameter is small, the aperture is close to a polygon having the number of corners equal to the number of aperture blades 6, but can be approximated as an aperture aperture having a predetermined small aperture diameter.
For this reason, the number of the aperture blades 6 is 3 or more, preferably 8 or more, more preferably 12 or more, or the arc shape on the inner diameter side corresponds to the opening diameter corresponding to a plurality of NA values. There is no problem if it is formed with a continuous curve that minimizes the error.

Next, the shape of the aperture blade 6 constituting the first embodiment will be described with reference to FIG.
Furthermore, the angle ∠POQ between the pin member 8 and the cam member 9 is formed from 90 ° to 270 ° with the optical axis 21 of the light beam as the center.
In the conventional optical aperture device, as shown in FIG. 9, the cam member 9 moves in the cam groove 10 b of the cam disk 10 with the pin member 8 as the rotation center.
Since the light shielding region 11 of the diaphragm blade 6 is located farther than the cam member 9 with respect to the pin member 8, the positioning error 13 of the light shielding region 11 of the diaphragm blade 6 is larger than the positioning error 12 of the cam member 9. The
According to the optical aperture device of the present invention, the angle ∠POQ between the pin member 8 and the cam member 9 is formed from 90 ° to 270 ° around the optical axis 21 of the light beam.
Therefore, as shown in FIG. 4, the pin member 8 and the cam member 9 are provided across the light shielding region 11 of the diaphragm blade 6 that forms the aperture opening 20 and shields the light beam.
Since the light shielding region 11 of the diaphragm blade 6 is located closer to the pin member 8 than the cam member 9, the positioning error 13 of the light shielding region 11 of the diaphragm blade 6 is reduced more than the positioning error 12 of the cam member 9. The
For this reason, it is possible to reduce the positioning error in the light shielding region 11 of the diaphragm blade 6, to suppress the occurrence of a subtle difference in resolving power, and the positioning accuracy of the diaphragm opening 20 at each NA value with a simple configuration. Improve.

Furthermore, in the first embodiment, linear cam grooves 10 a are formed toward the optical axis 21 at equal intervals in the cam disk 10.
For this reason, the shape of the cam groove 10b provided in the cam disk 10 does not need to be a curve or a shape connecting a plurality of points as in the conventional optical aperture device shown in FIGS.
As a result, the cam member 9 of the diaphragm blade 6 according to the first embodiment moves in a substantially tangential direction with respect to the center of the optical axis, so that the cam groove 10a provided in the cam disk 10 has a minimal radial cam groove. The aperture blade 6 can be rotated at 10a.
The cam member 9 of the diaphragm blade 6 is closest to the center of the optical axis when it is at the middle position of the rotation stroke of the diaphragm blade 6, and is separated from the center of the optical axis when the maximum numerical aperture and the minimum numerical aperture are used.
With such a diaphragm blade 6, the cam member 9 moves from outside to inside and further from inside to outside with respect to the center of the optical axis, so that the length of the cam groove 10 a can be reduced.
As a result, the cam groove 10a of the cam disk 10 is formed linearly with respect to the curved cam groove 10b as in the conventional example, so that the processing of the cam groove 10a of the first embodiment is further facilitated. Processing errors and processing costs can be reduced.

In the present embodiment, the case where the optical aperture device 4 is configured as the aperture stop (NA aperture) portion of the projection optical system PO has been described. Similarly, the optical aperture device 4 is used as the aperture stop (σ aperture) portion of the illumination system optical system IL. You may do it.
The present embodiment is not limited to this, and can also be applied to a method of manufacturing a device using the above exposure apparatus, particularly a semiconductor device such as a memory.
For example, in this embodiment, a device having a step of exposing an object to be exposed such as a wafer or glass coated on a resist and a step of developing the exposed object to be exposed using the exposure apparatus. It can also be applied to the manufacturing method.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS.
FIG. 6 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, a semiconductor chip manufacturing method will be described as an example.
The method comprises the steps of exposing a wafer using an exposure apparatus and developing the wafer, and specifically comprises the following steps.
In step 1 (circuit design), a semiconductor device circuit is designed.
In step 2 (mask production), a mask is produced based on the designed circuit pattern.
In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon.
Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using the mask and the wafer by the above exposure apparatus using the lithography technique.
Step 5 (assembly) is referred to as a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and an assembly process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including.
In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test.
Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 7 is a detailed flowchart of the wafer process in Step 4.
In step 11 (oxidation), the surface of the wafer is oxidized.
In step 12 (CVD), an insulating film is formed on the surface of the wafer.
In step 13 (electrode formation), an electrode is formed on the wafer.
In step 14 (ion implantation), ions are implanted into the wafer.
In step 15 (resist process), a photosensitive agent is applied to the wafer.
Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer.
In step 17 (development), the exposed wafer is developed.
In step 18 (etching), portions other than the developed resist image are removed.
In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed.
By repeatedly performing these steps, multiple circuit patterns are formed on the wafer.

It is a schematic block diagram of the exposure apparatus which has Example 1 of this invention. It is a block diagram of the optical aperture device of Example 1 of this invention. It is a block diagram of the aperture blade which comprises the optical aperture device of Example 1 of this invention. It is a block diagram of the aperture blade which comprises the optical aperture device of Example 1 of this invention. It is a top view of the optical aperture device of Example 1 of this invention. It is a flowchart for demonstrating manufacture of the device using the exposure apparatus of this invention. It is a detailed flowchart of the wafer process of step 4 of the flowchart shown in FIG. It is a block diagram of the conventional optical aperture device. It is a block diagram of the aperture blade which comprises the conventional optical aperture device.

Explanation of symbols

IL: Illumination optical system O: Optical axis center
PO ... Projection system optical system R ... Reticle W ... Wafer 1 ... Reticle chuck 2 ... Wafer chuck 3 ... Wafer stage 4 ... Optical aperture device 5 ... Surface plate 6・ ・ ・ Aperture blade 7 ・ ・ ・ Base plate 8 ・ ・ ・ Pin member 9 ・ ・ ・ Cam member 10
・ ・ ・ Cam disc 10a ・ ・ ・ Cam groove 10b ・ ・ ・ Cam groove 11 ・ ・ ・ Light shielding area 12 ・ ・ ・ Positioning error amount 13 generated in cam member ・ ・ ・ Shading error amount of light shielding area
20 ... Aperture aperture 21 ... Optical axis

Claims (6)

An annular base plate;
A plurality of aperture blades provided with a pin member and a cam member and rotatably supported by the pin member on the base plate;
An annular cam disk having a cam groove in which the cam member is movably inserted and rotates the diaphragm blade;
An optical diaphragm apparatus that forms diaphragm apertures with a predetermined numerical aperture by overlapping one region of the plurality of diaphragm blades and sliding the plurality of diaphragm blades together,
An optical diaphragm device, wherein the pin member and the cam member are provided across a light shielding region of the diaphragm blade that forms the diaphragm opening and shields light rays. 2. The optical diaphragm device according to claim 1, wherein an angle between the pin member and the cam member is 90 ° to 270 ° with the optical axis of the light beam as a center. The optical diaphragm apparatus according to claim 1 or 2, wherein the cam disk is formed with linear cam grooves toward the optical axis at equal intervals. A projection optical system comprising the optical aperture device according to claim 1, wherein an image of a pattern formed on a mask is projected onto a substrate.   An exposure apparatus comprising the projection optical system according to claim 4. 6. A device manufacturing method comprising: exposing a wafer using the exposure apparatus according to claim 5; and developing the wafer.

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