JPH0443629A - Charged particle beam lithography equipment - Google Patents

Abstract

PURPOSE:To make an aperture mask for beam formation exchangeable without breaking the vacuum inside a charged particle beam optical mirror cylinder, and improve the reliability and the workability of an equipment, by installing a preliminary chamber so as to be adjacent to the cylinder in which masks are arranged, and installing a mask exchange mechanism between the chamber and the cylinder. CONSTITUTION:The shapes of repetion pattern parts of an LSI pattern are different for each product kind and each layer, and therefore it is difficult to form the aperture for all repetition patterns in one aperture mask 36. As a result, at the arrangement position of the aperture mask 36 of an electron optical mirror cylinder 20, a preliminary chamber 49 linking with the mirror cylinder 20 is installed. A plurality of the aperture masks 36 of different aperture shapes for repetition pattern are previously set in the chamber 49, and the aperture mask 36 is exchanged according to necessity. Practically, a disk type mask retaining plate 50 wherein a plurality of the aperture mask 36 (361-364) are retained is rotated, and the necessary aperture mask 36 is set in the electron optical mirror cylinder 20, thereby performing drawing process.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a charged beam drawing apparatus for drawing patterns of semiconductor integrated circuits such as LSIs on a sample such as a mask or a wafer. The present invention relates to a charged beam lithography apparatus that generates a beam having a shape matching a repetitive pattern typified by a memory device and performs lithography at high speed.

(Prior Art) In recent years, LSI patterns have become increasingly finer and more complex, and electron beam lithography equipment has been used to form such patterns. Generally, in this apparatus, a beam forming means forms a rectangular or triangular beam (drawing unit figure), and a desired pattern is drawn by a combination of these drawing unit figures. Note that the beam shaping means shapes a rectangular or triangular beam by optically overlapping each aperture of two beam shaping aperture masks.

Recently, when drawing repetitive patterns such as memory patterns, an aperture corresponding to the basic repeating pattern is provided on one of two aperture masks, and this repeating pattern aperture is used to draw the pattern. A method (character projection method) for drawing repeated parts has been proposed.

In this method, a repeated basic pattern can be drawn in one shot, so in a memory pattern, etc., it is only necessary to draw as many times as the basic pattern is repeated, and the drawing throughput can be significantly improved.

However, this type of character projection method has the following problems. In other words, when drawing one LSI chip, as the device scale increases, exposure processing of 20 or more layers such as element isolation layers, contacts, gate polysilicon, and wiring layers becomes necessary, and even more types of LSI chips are drawn. Requires drawing one after another. The pattern of an LSI chip basically has a different repeated pattern shape for each device and each layer of the LSI chip. Therefore, it has been difficult to prepare all patterns on one beam shaping aperture mask.

As a countermeasure for this, we prepared multiple beam shaping aperture masks with different aperture shapes for repeated patterns.
It is conceivable to replace the aperture mask for each device and for each layer. However, when replacing the aperture mask, it is necessary to completely or locally destroy the vacuum state within the electron optical column, which is the path through which the electron beam generated from the electron gun irradiates the sample. For this reason, changing the drawing pattern layer or the type of LSI chip, which involves replacing the aperture mask, to perform a 1m drawing will significantly impede the operating rate of the drawing equipment, and will require readjustment of the electron optical system and the stability of the equipment. There were many problems in maintaining the .

These problems reduce LSI productivity and increase the production cost of LSI devices.As a result, 1. As SL advances rapidly and patterns become finer and more integrated, This poses a major problem in increasing the reliability of LSI patterns drawn with an electron beam drawing device and the operating rate of the device.

(Problem to be Solved by the Invention) As described above, in the character projection type charged beam lithography apparatus that has been proposed for the purpose of improving the lithography throughput, it is difficult to The beam shaping aperture mask must be replaced and installed inside the charged beam optical cylinder for each of the plurality of layers. At this time, each time the aperture mask is replaced, the vacuum state within the charged beam optical column is destroyed, which causes a significant decrease in the operating rate of the charged beam drawing apparatus. Furthermore, after replacing the aperture mask and restoring the vacuum state of the charged beam optical column, it is necessary to adjust the charged beam optical system again, which is a main cause of hindering the stability of the apparatus.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a beam shaping aperture mask used in a character projection method without destroying the vacuum inside the charged beam optical column. It is an object of the present invention to provide a charged beam lithography device that can be replaced and can improve the reliability and operating rate of the device.

[Structure of the Invention] (Means for Solving the Problems) The object of the present invention is to draw a pattern having repetition by a character projection method, and furthermore, to provide an aperture mask for beam shaping having an aperture for the repetition pattern. The reason is that the charged beam optical column can be replaced without destroying the vacuum level.

That is, the present invention provides a charged beam writing apparatus that forms a dimension-variable beam and a beam corresponding to a repetitive basic pattern by combining a plurality of beam-forming aperture masks to draw a desired pattern on a sample. The present invention is characterized in that a preliminary chamber is provided adjacent to the charged beam optical column, and a mask exchange mechanism is provided for exchanging masks between the preliminary chamber and the charged beam optical column.

More specifically, the present invention provides a first beam shaping aperture mask in which a beam shaping aperture is formed, and a second beam shaping aperture mask in which a beam shaping aperture and a repeating pattern aperture are formed, in a charged beam optical column. In a charged beam drawing device, a desired pattern is drawn on a sample by arranging two aperture masks and forming a beam having variable dimensions and a beam corresponding to a repetitive basic pattern by optically overlapping the apertures of these masks. , a pre-chamber that is provided adjacent to a region where the second mask of the charged beam optical column is arranged and accommodates a plurality of second masks having different shapes of repeating pattern apertures, and the pre-chamber and the charged beam It is characterized by comprising a mask exchange mechanism for exchanging the second mask between the optical lens barrel and the second mask.

Further, the present invention provides a mask exchange mechanism in the charged beam writing apparatus, including a mask holding plate on which a plurality of masks are placed, a part of which is located in the charged beam optical column, and a part of which is located in the preliminary chamber; It is characterized by comprising a drive mechanism that rotates the holding plate around an axis parallel to the beam axis.

Furthermore, the present invention provides a mask exchange mechanism in the charged beam writing apparatus, in which a plurality of masks are arranged, one part is located in the charged beam optical column, the other part is located in the preliminary chamber, and the mask exchange mechanism is arranged along the beam axis direction. A first driving mechanism that rotates each mask holding plate independently around an axis parallel to the beam axis; It is characterized by comprising a second drive mechanism that moves in direction J.

(Function) According to the present invention, by selecting and using a plurality of beam shaping aperture masks using a character projection method, it is possible to prepare a large number of patterns depending on the type of LSI device and the layer to be exposed. This makes it possible to draw various types of LSI chips one after another. Furthermore, by exchanging aperture masks between the charged beam optical column and the preliminary chamber, multiple aperture masks can be exchanged without disturbing the vacuum level of the charged beam optical column. This makes it possible to improve operating rates and stability. Such an automatic exchange mechanism for beam shaping aperture masks will become more effective in the future as patterns become finer and more integrated, and charged beam lithography systems are expected to dramatically improve their throughput. It is expected that it will be effective.

(Example) Hereinafter, details of the present invention will be explained along with the illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing an electron beam lithography apparatus according to an embodiment of the present invention. In the figure, 10 is a sample chamber, and within this sample chamber 10 is housed a table 12 on which a sample 11 such as a glass mask or a semiconductor wafer is placed. The table 12 is driven by a table drive circuit 13 in the X direction (left and right directions on the paper) and the Y direction (front and back directions on the paper).

The moving position of the table 12 is measured by a position circuit 14 using a laser length measuring needle or the like.

An electron optical column 20 is arranged above the sample chamber 10. The electron optical lens barrel 20 includes an electron gun 21, various lenses 21 to 26, a blanking deflector 31, a beam dimension variable deflector 32, a main deflector 33 for beam scanning, and a sub-deflector for beam scanning. A device 34, aperture masks 35, 36 for beam shaping, etc. are arranged. Further, at the position where the aperture mask 36 of the electron optical lens barrel 20 is arranged, a preliminary chamber 49 is provided in communication with the lens barrel 20, and a mask exchange mechanism described later is used to connect the lens barrel 20 and the preliminary chamber 49. The aperture mask 36 is constructed to be replaceable.

In the electron optical lens barrel 20, the main deflector 33 positions a predetermined unit drawing area (subfield), and the sub deflector 3
4 to position the figure drawing position within the subfield, and control the beam shape by the beam size variable deflector 32 and shaping aperture mask 35, 36, and draw the LSI chip pattern while continuously moving the table in one direction. Drawing processing is performed on drawing stripe areas collected within a drawable range by one continuous movement of the table.

In other words, a writing stripe area is written, which is a collection of frame areas obtained by dividing the LSI chip pattern area into strips according to the deflection width of the beam.

Furthermore, the table 12 is moved stepwise in a direction perpendicular to the direction of continuous movement, and the above process is repeated to sequentially draw the drawing stripe area.

On the other hand, the control computer 40 has a magnetic disk (storage medium) 4.
1 is connected, and the drawing pattern data of the LSI chip is stored in this disk 41. The drawing pattern data of the LSI chip read from the magnetic disk 41 is temporarily stored in the pattern memory (data buffer section) 42 for each drawing stripe area.

The drawing pattern data for each drawing stripe stored in the pattern memory 42, that is, the drawing stripe information consisting of the drawing position, basic figure data, etc., is processed by the pattern data decoder 43 and the drawing data decoder 44, which are data decoding units. It is decoded and sent to blanking circuit 45, beamformer driver 46, main deflector driver 47 and sub deflector 48.

That is, the pattern data decoder 43 inputs the drawing pattern data for each drawing stripe area, expands the compressed drawing figure data based on the repetition information of the pattern defined as the drawing stripe data, and decodes the drawing pattern data for each drawing stripe area. A drawing unit figure that can be formed by combining the drawing figure data defined in the drawing pattern data with beam shaping aperture masks 35 and 36 while determining and decoding the area to be drawn for each subfield in the live area drawing process. (7) Based on this data, beam control data is created and sent to the blanking circuit 45, where a desired pattern is drawn.

Next, a drawing process using this apparatus will be explained. FIG. 2 is a pattern example showing a part of an LSI pattern to be drawn. This pattern consists of a pattern section 1 having a huge number of repetitions such as a memory cell section, a pattern section 2 surrounding the memory cell section with relatively few repetitions, and a pattern section 17 having no repeating structure at all. It consists of 3.

A beam shaping aperture mask 35 (first aperture) used when drawing such a pattern has a rectangular aperture 35a shaped like the shape shown in FIG. 3(a). In addition, aperture masks for beam shaping (
The second aperture 36 is divided into sections as shown in FIG. 3(b), and an aperture for a repeating pattern or an aperture for beam shaping is formed in each section. That is, repeating pattern apertures 36b to 36i corresponding to repeating basic patterns are formed in section B-1.

Also, in section A, there is an aperture 36b for a repeating pattern.
36i, an aperture 36a having the shape shown in FIG. 3(c) is formed in order to draw patterns other than those which cannot be formed. By combining the apertures 35a and 36a, a rectangular beam and a triangular beam can be formed as shown in FIG. 3(d).

When drawing an LSI pattern using the above aperture mask, 1. Therefore, for a specific pattern in which a pattern exists in the second aperture mask 36 in the repetitive pattern portion defined in the drawing stripe data, the combination of the first and second aperture masks 35 and 36 is used. Specific tag information is assigned to enable exposure.

Based on this tag information, the first aperture 35
The beam projection image of the rectangular aperture 35a is pattern-exposed by aligning the projection beam to one section of the second aperture mask 36. For other pattern parts, the drawing unit figures are divided into drawing unit figures of only rectangular beams and triangular beams as shown in FIG. Draw a pattern.

Here, LSI patterns have different shapes of repeating pattern parts depending on product type and layer (element isolation layer, contact, etc.), and it is difficult to form apertures for all repeating patterns in one aperture mask 36. It is. Therefore, a plurality of aperture masks 36 having different aperture shapes for repeated patterns are set in advance in the preliminary chamber 49, and the aperture masks 36 are replaced as necessary.

Specifically, as shown in FIG. 4, by rotating a disc-shaped mask holding plate 50 holding a plurality of aperture masks 36 (3G, to 364), necessary aperture masks 36 are electronically removed. It is set in the optical lens barrel 20 and subjected to the drawing process as described above. Note that the mask holding plate 50 has a fifth
As shown in the figure, a part is disposed within the electron optical lens barrel 20 and a part is disposed within the preliminary chamber 49, and is rotatable by a drive section 51 about an axis parallel to the beam axis. An opening is formed in a portion where the aperture mask 36 is placed.

Furthermore, since there is a limit to the number of aperture masks 36 that can be held using the replacement method shown in FIG. The required mask holding plate 5° is selected by driving the mask holding plate 50 in the vertical direction, and the aperture mask 36 held on the mask holding plate 50 is selected by the rotation mechanism of the mask holding plate 50, and the aperture mask 36 is moved inside the electron optical VI cylinder 2o. Set to , and use it for drawing processing. As a result, it is possible to achieve processing performance comparable to that of the pre-reduction transfer device, which is currently the mainstream device for pattern transfer to wafers, at a resolution higher than that device.

In reality, the mask holding plates 50 (50, to 5o,) are spaced apart along the beam axis direction, as shown in FIG. In this case, the aperture mask 36 is not set. When selecting one of the aperture masks 36, the mask holding plate 5° (seventh
The figure shows 50. ) is at a predetermined height position.
2, the mask holding plate 5o is moved in the vertical direction. Furthermore, the selected mask holding plate 50. is rotated by the drive unit 51 so that the selected aperture mask 36 is positioned at the imaging position of the aperture 35a.

In addition, the other mask holding plate 50 includes an aperture mask 36
The aperture mask 36 is rotated so that the apertures for which no . Thereby, the selected aperture mask 36 can be set at a predetermined position, and it becomes possible to perform drawing using the character projection method.

Thus, according to this embodiment, by simply rotating the mask holding plate 50 holding a plurality of aperture masks 36,
The aperture mask 36 can be exchanged between the electron optical lens barrel 20 and the preliminary chamber 49, and there is no need to break the vacuum of the electron optical tIi cylinder 20 when exchanging the aperture mask 36.

Furthermore, by using a plurality of mask holding plates 50 and moving them in the axial direction while rotating the mask holding plates 500, it is possible to select a large number of aperture masks 36 (16 in FIG. 7), and various repetitions can be performed. It becomes possible to correspond to patterns.

Therefore, in a character projection type electron beam lithography system that exposes the basic pattern of a repeating pattern part, such as a memory device, all at once, it is possible to significantly reduce the time required to replace the aperture mask and the associated equipment overhead time. As a result, the operating rate of the charged beam lithography apparatus can be increased, and the productivity of LSI can be increased.

Note that the present invention is not limited to the embodiments described above. For example, the optical system configuration of the electron beam drawing apparatus is not limited to the same as shown in FIG. 1, but can be changed as appropriate according to specifications. In addition, in the embodiment, explanation will be given using an electron beam as an example, but it is not limited to electron beams, but can be applied to a charged beam drawing device using an ion beam, and can be applied to a bead shape other than a repetitive pattern transfer part. In addition to the shot method using a variable shaped beam, it is also applicable to devices using an elliptical beam. In addition to the drawing method in which drawing is performed while continuously moving the table on which the sample is placed in one direction, it is also possible to apply a step-and-repeat method in which the table is moved step by step and drawing processing is performed for each unit area while the table is stopped. In that case, it is also possible to rotate the mask holding plate for each unit area and select the necessary aperture as appropriate.

Further, in the embodiment, a plurality of aperture masks are placed on the mask holding plate, but instead of this, the apertures may be formed on the mask holding plate itself, that is, the aperture mask and the mask holding plate may be formed integrally. Further, in the embodiment, a rotatable mask holding plate is used as the mask exchange mechanism, but the present invention is not limited to this, and any mechanism that can transport the aperture mask between the charged beam optical column and the preliminary chamber may be used. For example, a mask magazine containing a plurality of aperture masks may be prepared in the preliminary chamber, and any one of the magazines may be transported to a predetermined position within the charged beam optical column. Further, in the embodiment, the beam is formed by a combination of two aperture masks, but it is also possible to form the beam by a combination of three or more aperture masks spaced apart in the beam axis direction. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, in a character projection type charged beam drawing apparatus capable of exposing a basic pattern of a repeating pattern typified by a memory device with one projection image of an aperture, A preliminary chamber is provided adjacent to the 6z electric beam optical column, and a mask exchange mechanism is provided to exchange the aperture mask between this chamber and the charged beam optical column. The beam shaping aperture mask, which needs to be replaced depending on the layer to be exposed, can be replaced without disturbing the vacuum level of the charged beam optical column, significantly increasing the operating rate and stability of the equipment. It can be realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an electron beam drawing apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a part of an LSI pattern to be drawn, and FIG. 3 is a schematic diagram showing each part of an aperture mask for beam shaping. FIG. 4 is a schematic diagram showing an aperture shape, FIG. 4 is a plan view showing an example of a mask exchange mechanism, FIG. 5 is a sectional view showing a specific configuration of the aperture exchange mechanism, and FIG. FIG. 7, which is a schematic diagram for explanation, is a sectional view showing a mechanism for exchanging a plurality of aperture masks. DESCRIPTION OF SYMBOLS 10... Sample chamber, 11... Sample, 12... Table, 20... Electron optical column, 21... Electron gun, 22-26... Lens, 31-34... Deflection 35.36... Aperture mask for beam shaping, 35
a, 36g...beam shaping aperture, 38b-3
6th...Aperture for repeating pattern, 40...Control computer, 46...Beam shaper driver, 47...Main deflector driver, 48...Sub deflector driver, 49...Preliminary room, 50... Aperture holding plate, 51... Rotation drive section, 52... Vertical drive section. Applicant's agent Patent attorney Takehiko Suzue (d) (e) Figure (a) (C) Figure Z-49 Figure

Claims (4)

[Claims] (1) In a charged beam drawing device that forms a dimension-variable beam and a beam corresponding to a repetitive basic pattern by combining a plurality of beam-forming aperture masks to draw a desired pattern on a sample, the masks are arranged. A preliminary chamber for accommodating a mask different from the mask is provided adjacent to the charged beam optical column, and a mask exchange mechanism is provided for exchanging the mask in the preliminary chamber with the mask of the charged beam optical column. A charged beam lithography device featuring: (2) A first beam shaping aperture mask in which a beam shaping aperture is formed and a second aperture mask in which a beam shaping aperture and a repeating pattern aperture are formed are arranged in the charged beam optical column. death,
In a charged beam writing apparatus that forms a dimensionally variable beam and a beam corresponding to a repetitive basic pattern by optically overlapping the apertures of these masks to draw a desired pattern on a sample, the charged beam optical column comprises: A preliminary chamber is provided adjacent to the area where the second mask is arranged and accommodates a plurality of second masks having different shapes of repeating pattern apertures, and a mask of the preliminary chamber and a mask of the charged beam optical column. 1. A charged beam lithography apparatus comprising: a mask exchange mechanism for exchanging a mask; (3) The mask exchange mechanism includes a mask holding plate on which a plurality of masks are placed, part of which is located in the charged beam optical column and part of which is located in the preliminary chamber, and a mask holding plate that is parallel to the beam axis. 3. The charged beam lithography apparatus according to claim 1, further comprising a drive mechanism that rotates the charged beam lithography device about a central axis. (4) The mask exchange mechanism includes a plurality of masks, some of which are located in the charged beam optical column and some of which are located in the preliminary chamber, and which are spaced apart along the beam axis direction. a holding plate; a first drive mechanism that independently rotates these mask holding plates about an axis parallel to the beam axis;
The second one moves each mask holding plate in a direction parallel to the beam axis.
Claim 1 or 2, characterized in that the drive mechanism comprises:
Charged beam lithography device described in .