JP2001244171A - Beam-shaping aperture, its manufacturing method, charged particle beam exposure system, and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a beam shaping aperture which has no round corner sections. SOLUTION: A rectangular upper carved hole 2 is formed into a single discoid member (made of tantalum or molybdenum), from the upper surface of the member to the central part of the member in the thickness direction. In addition, a rectangular lower carved hole 3 is formed into the member, extending from the lower surface of the member to the central part of the member in the thickness direction. These holes 2 and 3 overlap each other and form an opening at the central part. Since the holes 2 and 3 intersect each other at right angles, the opening also becomes rectangular (in many cases, square) in shape. Although the holes 2 and 3 have round corner sections formed at the time of carving the holes 2 and 3, the rectangular opening has no round corner section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam shaping aperture suitable for use in a charged particle beam exposure apparatus such as an electron beam exposure apparatus, a method of manufacturing the same, a charged particle beam exposure apparatus,
And a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In recent years, with miniaturization of semiconductor elements, an exposure apparatus using an electron beam has been developed. Since the electron beam has a higher beam straightness than light, it is possible to expose a finer shape than light. In such an exposure apparatus, a beam shaping aperture is used to determine a range to be exposed at a time. For example, in the case of an exposure apparatus that transfers a pattern formed on a reticle to a wafer, a beam shaping aperture is used to determine a range in which light from an illumination optical system irradiates the reticle.

[0003] Such a beam shaping aperture is often made of tantalum or molybdenum, which are high melting point metals capable of blocking an electron beam. As shown in FIG. 7, a method of forming an opening in the beam forming aperture is as follows: a plate made of tantalum or molybdenum is processed by electric discharge machining using a square electrode 23 on a flat metal 21 to form an opening 22. Are often formed.

[0004]

However, in the conventional manufacturing method as shown in FIG. 7, there is a limit in reducing the four corners R of the opening 22. In the EDM method, the machining electrode is brought close to the workpiece, and a high-voltage pulse is applied to both to melt and remove the workpiece,
The shape of the electrode is transferred to the workpiece. The discharge gap at that time is usually about 20 μm. Therefore, 4
Even if a square electrode 23 having no R portion at the corner is used, as shown in FIG. 8, the workpiece has a hole (opening) having an R portion corresponding to the discharge gap around the corner of the electrode 23 as shown in FIG. Part)
22 is processed. The corner R is desirably zero in view of the function of the aperture, but it is inevitable that the R portion remains in the manufacturing method as shown in FIG.

For example, in an exposure apparatus of a division exposure transfer system, a pattern to be exposed and transferred is divided into a plurality of sections called subfields, one subfield is transferred at a time, and a plurality of transfer areas are joined. The entire exposure transfer is performed. In such a case, if there is an R at the corner of the beam shaping aperture, a subfield must be formed avoiding the R portion, so that the skirt around the subfield becomes wider, and as a result, The reticle becomes large.

[0006] Then, the skip width of the stage between the deflection width and the main field (a group of subfields having a width determined by the maximum deflection width) increases, so that not only the load on the optical system and the stage increases but also the exposure transfer. There is a problem that it takes time and the throughput is reduced.

The present invention has been made in view of such circumstances, and has a beam forming aperture having no R portion at a corner.
It is an object of the present invention to provide a method for manufacturing the same, a charged particle beam exposure apparatus using such a beam shaping aperture, and a method for manufacturing a semiconductor device using such a charged particle beam exposure apparatus.

[0008]

According to a first aspect of the present invention, there is provided a beam forming aperture made of a single member and having a rectangular opening. Are formed so as to be orthogonal to each other,
The portion where these holes overlap is a beam forming aperture (claim 1) forming an opening.

In this means, rectangular holes are separately formed from two opposing directions (the entrance side and the exit side of the beam), and the rectangles are positioned so as to be orthogonal to each other. Each of the rectangular holes overlaps at a part (preferably near the center) in the thickness direction of the single member, and forms an opening at that part. Therefore, if the illumination optical system is designed so that the beam of the charged particle beam forms an image of the opening on the illumination portion (for example, the reticle surface), an illumination range having no R portion at the corner can be obtained.

[0010] A second means for solving the above-mentioned problems is as follows.
A method of forming a beam forming aperture as the first means, wherein a through-hole serving as a reference hole is machined in a single member, and a rectangular shape is formed from one direction of the single member with reference to the reference hole. The engraved hole is processed, and then the rectangular engraved hole is processed in a direction perpendicular to the rectangular engraved hole from the opposite direction of the single member with respect to the reference hole. A method of manufacturing a beam forming aperture, wherein a through portion is formed therebetween (claim 2).

In this means, first, a through hole serving as a reference hole is formed, and a tool is set on the basis of this hole to form a rectangular engraved hole. Can be easily adjusted. In addition,
It goes without saying that the outer diameter of this reference hole must be smaller than the width of the engraved hole forming the short side of the opening.

A third means for solving the above-mentioned problem is as follows.
A beam shaping aperture having a rectangular opening,
A beam shaping aperture (claim 3) wherein two members having rectangular openings are overlapped and fixed so that the respective rectangles are oriented at right angles to each other.

[0013] Also in this means, since the aperture of the aperture serves as an opening common to the openings of the two members, it is possible to form an illumination area having no R portion at the corner.

A fourth means for solving the above-mentioned problem is as follows.
A charged particle beam exposure apparatus having a beam shaping aperture according to any one of the first to third means (Claim 4).

In this means, an illumination area having no R portion at the corner can be obtained. Therefore, even when performing divided exposure, it is not necessary to widen the skirt around the subfield. As a result, the reticle or mask can be removed. Can be smaller.
Therefore, it is possible to prevent the load of the optical system and the stage from increasing, and it is possible to solve the problem that the exposure transfer takes time and the throughput is reduced.

According to a fifth aspect of the present invention, there is provided a process for transferring a circuit pattern formed on a reticle or a mask onto a wafer using a charged particle beam exposure apparatus as the fourth means. (Claim 5).

As described above, according to the fourth means,
The size of the reticle or mask can be reduced.
Therefore, in this means, a semiconductor device having a fine pattern can be manufactured with a high throughput.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A and 1B are conceptual perspective views of an example of a beam shaping aperture according to an embodiment of the present invention when viewed from above and below. In FIG. 1, 1
Is a single member, 2 is an upper engraved hole, and 3 is a lower engraved hole.

A rectangular upper engraved hole 2 is formed from above a single disk-shaped single member (tantalum or molybdenum) to the center in the thickness direction. From below, a rectangular lower engraving hole 3 is formed up to the center in the thickness direction. These holes overlap at the center to form an opening. Since the upper engraving hole 2 and the lower engraving hole 3 are orthogonal, the opening is also rectangular (often square). Each of the upper engraved hole 2 and the lower engraved hole 3 has an R portion formed at a corner portion due to processing, but the opening is a rectangle having no R portion.

FIG. 2 is a diagram showing a method of manufacturing the beam shaping aperture shown in FIG. 1, wherein the left side is a plan view and the right side is a longitudinal sectional view. In the following drawings, the same components as those shown in the preceding drawings are denoted by the same reference numerals, and description thereof may be omitted. In FIG. 2, 4 is a reference hole,
5 is an opening.

For ease of explanation, in FIG. 2, the thickness direction of the aperture (X-
Set the YZ orthogonal coordinate system. First, as shown in (a), at the center position 0 of the single member 1 serving as an aperture,
A through hole serving as a reference hole 4 is machined from one direction. The thickness t of the single member is at least twice the thickness sufficient to absorb the beam. That is, for example, t = 500 μm. At this time, the diameter d of the reference hole 4 is such that when a length of one side of a desired square to be the opening 5 is a, the relationship is a ≧
d. For example, let a be 1100 μm and d be 5
00 μm.

Next, as shown in FIG.
Then, a rectangular upper engraving hole 2 is machined from the upper side. At this time, processing is performed so that the long side of the rectangular upper engraving hole 2 is parallel to the Y axis. The engraving may be performed by electric discharge machining, or may be performed by cutting using a cutting tool. At the time of processing, the length of the short side of the rectangular upper engraving 2 is set to be the same as the length a of one side of a desired square to be the opening 5. The long side b is a length that satisfies the relationship of b ≧ a + 2r, where r is the radius of the corner roundness generated by processing. This is because the corner R
It means that even if the occurrence occurs, it does not reach the opening 5. And the depth c of the upper engraving hole 2 is t-c,
The thickness should be greater than enough to absorb the beam. For example, a is 1100 μm, b is 1300 μm, c is 250 μm
And

Next, as shown in FIG.
Then, a rectangular lower engraving hole 3 is machined from below. At this time, the lower engraving hole 3 is processed so that the lower engraving hole 3 and the upper engraving hole 2 shown in (b) intersect at right angles on the central axis of the aperture. That is, processing is performed so that the long side of the lower engraving hole 3 is parallel to the X axis. At this time, the length of the long side and the short side of the lower carved hole 3 is
If the size is the same as that of the upper engraved hole 2, the electrode and the cutting tool used in the step shown in FIG. And the depth e of the lower engraving hole 3 is t ≧ e ≧ t
The opening 5 can be penetrated by setting the depth such that the relationship of -c is satisfied. However, since it is necessary to leave a sufficient thickness to absorb the beam, in the above example, e
Is set to, for example, 260 μm.

FIG. 3 is a diagram showing another example of the beam shaping aperture according to the embodiment of the present invention. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view. In FIG.
Is an upper plate, 7 is a hole provided in the upper plate, 8 is a lower plate, 9 is a hole provided in the lower plate, and 10 is an opening.

The beam forming aperture is formed by an upper flat plate 6.
And the lower flat plate 8 are fixedly formed. The upper flat plate 6 and the lower flat plate 8 are provided with rectangular holes 7 and 9, respectively, which are orthogonal to each other. Therefore, a rectangular opening 10 is formed at the intersection. The rectangular holes 7 and 9 are formed by electric discharge machining or machining, and the R portions are formed at the corners thereof, but the R portions are not formed at the corners of the opening 10. The upper flat plate 6 and the lower flat plate 8 each have a thickness sufficient to independently absorb the beam.

FIG. 4 is a schematic diagram of an optical system of a charged particle exposure apparatus according to an embodiment of the present invention. In FIG. 4, reference numeral 11 denotes a charged particle beam source, 12 denotes an illumination lens, 13 denotes a beam shaping aperture, 14 denotes an aperture stop, 15 denotes a mask, 16 denotes a projection lens, 17 denotes an aperture stop, and 18 denotes a wafer.

The charged particle beam emitted from the charged particle beam source 11 uniformly illuminates the mask 15 with the illumination lens 12. The image of the pattern formed on the mask 15 is formed on the wafer 18 by the projection lens, and the resist on the wafer 18 is exposed. Aperture stops 14 and 17 are provided to cut scattered radiation and limit the aperture angle. These configurations are the same as those of the conventional charged particle beam exposure apparatus.

In this embodiment, the beam shaping aperture 13 is provided at a position optically conjugate with the mask 15. In this embodiment, the beam shaping aperture 13 of the present invention is used as the beam shaping aperture 13 in the present embodiment. Therefore, mask 1
The illumination area No. 5 is a square having no R portion. For example, when performing divided exposure transfer, the entire illumination area can be used as a subfield. Accordingly, the subfield becomes large, and the reticle and the mask can be made small accordingly, so that the throughput can be improved in re-exposure transfer.

In the beam shaping aperture shown in FIG. 3, the upper flat plate 6 and the lower flat plate 8 are overlapped with each other, and the shaping aperture is constituted by the common opening. But,
When the charged particle beam exposure apparatus has two or more positions optically conjugate to the surface to be illuminated in its illumination optical system, beam shaping having a rectangular opening separately in any two of them. The same effect as that shown in FIG. 3 can be obtained by providing an aperture, opening a rectangular opening in each beam shaping aperture, and making the openings orthogonal to each other.

FIG. 5 is a flowchart showing an example of the semiconductor device manufacturing method of the present invention. The manufacturing process of this example includes the following main processes. Wafer manufacturing process for manufacturing a wafer (or wafer preparing process for preparing a wafer) Mask manufacturing process for manufacturing a mask to be used for exposure (or mask preparing process for preparing a mask) Wafer processing process for performing necessary processing on a wafer Wafer Chip assembling step of cutting out the chips formed on the chip one by one to make it operable Chip inspecting step of inspecting the resulting chips Each of the steps further includes several sub-steps.

Among these main steps, the main step that has a decisive effect on the performance of the semiconductor device is the wafer processing step. In this step, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing step includes the following steps. A thin film forming step (using CVD, sputtering, etc.) for forming a dielectric thin film, a wiring portion, or a metal thin film for forming an electrode portion, which serves as an insulating layer. A lithography process of forming a resist pattern using a mask (reticle) in order to selectively process etc. An etching process of processing a thin film layer or a substrate according to a resist pattern (for example, using a dry etching technique) An ion / impurity implantation diffusion process Resist stripping step Inspection step of inspecting the processed wafer Further, the wafer processing step is repeated by a necessary number of layers to manufacture a semiconductor device that operates as designed.

FIG. 6 is a flowchart showing a lithography step which is the core of the wafer processing step shown in FIG. This lithography step includes the following steps. A resist coating step of coating a resist on a wafer on which a circuit pattern has been formed in the preceding step An exposing step of exposing the resist A developing step of developing the exposed resist to obtain a resist pattern Stabilizing the developed resist pattern The above-described semiconductor device manufacturing process, wafer processing process, and lithography process are well known, and will not require further explanation.

In this embodiment, the charged particle beam exposure apparatus according to the present invention as shown in the above embodiment is used in the process shown in FIG. Therefore, a fine pattern can be accurately transferred to a wafer by exposure and transfer, so that a semiconductor device having a pattern with a fine line width can be manufactured with high yield.

[0034]

As described above, according to the first and third aspects of the present invention, it is possible to obtain an illumination range having no R portion at the corner. In addition, when these beam forming apertures are used, the size of the reticle can be reduced, so that the stroke of the reticle stage can be reduced, and the size and cost of the stage can be reduced. Further, since the width of the step of the electron beam in the next field after the spot exposure can be reduced, the deflection time can be shortened and the throughput can be improved.

According to the second aspect of the present invention, the beam forming aperture according to the first aspect can be easily manufactured.

According to the fourth aspect of the present invention, the size and cost of the stage can be reduced. Also, after spot exposure,
Since the width of the step of the electron beam in the next field can be reduced, the deflection time can be reduced, and the throughput can be improved. .

In the invention according to claim 5, a semiconductor device having a fine pattern can be manufactured with high throughput.

[Brief description of the drawings]

FIG. 1 is a conceptual perspective view of an example of a beam shaping aperture according to an embodiment of the present invention when viewed from above and below.

FIG. 2 is a diagram showing a method of manufacturing the beam shaping aperture shown in FIG.

FIG. 3 is a diagram showing another example of the beam shaping aperture according to the embodiment of the present invention.

FIG. 4 is a schematic diagram of an optical system of a charged particle exposure apparatus which is an example of an embodiment of the present invention.

FIG. 5 is a flowchart illustrating an example of a semiconductor device manufacturing method according to the present invention.

FIG. 6 is a flowchart showing a lithography process.

FIG. 7 is a diagram showing a method for manufacturing a conventional beam shaping aperture.

FIG. 8 is a diagram showing shapes of electrodes and openings when a conventional beam shaping aperture is manufactured by electric discharge machining.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single member, 2 ... Upper engraving hole, 3 ... Lower engraving hole, 4 ... Reference hole, 5 ... Opening, 6 ... Upper flat plate, 7 ... Hole provided in upper flat plate, 8 ... Lower flat plate, 9 ... Holes provided in the lower flat plate, 10 ... opening, 11 ... charged particle beam source, 12
... Illumination lens, 13 ... Beam shaping aperture, 14 ...
Aperture stop, 15: mask, 16: projection lens, 17:
Aperture stop, 18 ... wafer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 37/305 H01L 21/30 541B 541S

Claims (5)

[Claims] 1. A beam forming aperture made of a single member and having a rectangular opening, wherein rectangular holes are formed so as to be orthogonal to each other from two opposing directions, and a portion where these holes overlap each other is an opening. Beam shaping aperture forming part. 2. The method for forming a beam forming aperture according to claim 1, wherein a through-hole serving as a reference hole is machined in a single member, and subsequently, a single hole is formed on the basis of the reference hole. A rectangular engraved hole is machined from the direction, and subsequently, a rectangular engraved hole is machined in a direction perpendicular to the rectangular engraved hole from the opposite direction of the single member with respect to the reference hole. A method for manufacturing a beam forming aperture, characterized in that a penetrating portion is formed between the hole and a carved hole. 3. A beam shaping aperture having a rectangular opening, characterized in that two members having a rectangular opening are overlapped and fixed so that the respective rectangles are oriented at right angles to each other. Beam forming aperture. 4. One of claims 1 to 3
A charged particle beam exposure apparatus comprising the beam shaping aperture according to item 9. 5. A method for manufacturing a semiconductor device, comprising a process of transferring a circuit pattern formed on a reticle or a mask to a wafer using the charged particle beam exposure apparatus according to claim 4.