JP2005101292A - Charged particle beam projecting exposure device, mask for exposure, method of manufacturing mask for exposure, and charged particle beam projecting exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle beam projecting exposure device that uses a mask and can suppress the expansion of a charged particle beam caused by the repulsion of charged particles to each other due to a Coulomb force by improving the mechanical strength of a stencil mask, and at the same time, reducing the number of openings of the mask. <P>SOLUTION: The charged particle beam projecting exposure device 100 and the stencil mask 6 manufactured by narrowing a mask pattern used for exposure are used. When the exposure device 100 performs exposure by using the stencil mask 6, the line width of a pattern transferred to the wafer 9 is thickened by moving an electronic beam 2 with respect to a wafer 9 by changing the electron optics-based condition of the electron beam 2 and the position of the stencil mask 6 or the wafer 9. Consequently, the opening area of the stencil mask 6 can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a charged particle beam projection exposure apparatus using a mask. The present invention also relates to a mask used for charged particle beam projection exposure. For example, the present invention relates to a mask used for exposure, a mask manufacturing method, and an exposure apparatus using the mask.

  As this electron beam projection exposure technique, in Japanese Patent Application Laid-Open No. 9-139344, a beam diameter of an electron beam is set to about 1 mm square on a mask, a 4 times stencil mask is used as an exposure mask, and the maximum exposure area on a wafer is 250 μm. There has been proposed a method of performing exposure at a corner (this simultaneously exposed region is called a subfield). The stencil mask used here is composed of a large number of divided masks obtained by dividing the entire pattern of the chip formed on the sample, and a method of performing batch exposure with an electron beam on the divided masks has been proposed.

  FIG. 5 shows a sectional view of the stencil mask 6 used in the electron beam projection exposure technique. The stencil mask 6 includes a pattern opening 12 (opening area), a membrane 13, a beam 14, and a support substrate portion 15. In the stencil mask 6, an opening (hereinafter referred to as a mask pattern) corresponding to the mask pattern is formed in a very thin film, specifically, a film composed of 0.1 um to 2 um Si (silicon) or the like in order to finely process the pattern. Open area). For this reason, the donut-shaped pattern shown in FIG. 6 (a) has a problem that a pattern cannot be formed because the pattern at the center of the opening is lost (the center of the opening falls due to gravity) (so-called donut problem). ). In order to deal with this problem, for example, Japanese Patent Laid-Open No. 6-132206 proposes a method of dividing such a pattern into a plurality of masks, which is generally called complementary division.

  In addition to the donut-shaped pattern, the leaf-shaped pattern shown in FIG. 6B and the pattern having a large aspect ratio shown in FIG. For this purpose, a complementary division method has also been proposed (Japanese Patent Laid-Open No. 2001-244192).

  In the stencil mask used in the electron beam projection exposure technique, an opening corresponding to the mask pattern is required in a film made of very thin Si as described above. For this reason, the stencil mask has low mechanical strength, and depending on the distribution of the openings, the portion remaining as a beam becomes thin and is very distorted. In addition, since charged particle beams (mainly electron beams) with a charge are used for exposure, charged particles that have passed through the opening of the stencil mask repel each other due to Coulomb force, and the beam spreads. The resolution limit deteriorates.

  In order to solve these problems, the above-described complementary division is effective. This is because if the pattern is divided into a plurality of masks, the aperture ratio will be one times the number of masks, and if the aperture ratio decreases, the distance between the patterns will increase accordingly, that is, the remaining part of the beam will become thicker and the mechanical strength will increase. Because it becomes high.

As described above, the stencil mask has a great demand for improvement in mechanical strength and a reduction in the opening, but for example, Japanese Patent Laid-Open No. 9-139344 only discloses collective exposure of electron beams, and Japanese Patent Laid-Open No. No. 132206 and Japanese Patent Laid-Open No. 2001-244192 do not disclose a technique for further improving the mechanical strength of the stencil mask and reducing the number of openings.
JP-A-9-139344 JP-A-6-132206 JP 2001-244192 A

  The object of the present invention is to further improve the mechanical strength by the complementary division, and to improve the mechanical strength of the stencil mask. It is another object of the present invention to reduce the opening of the stencil mask and prevent the charged particles from repelling each other due to Coulomb force and spreading the beam.

The charged particle beam projection exposure apparatus of the present invention,
In a charged particle beam projection exposure apparatus that exposes a substrate surface with a charged particle beam using a mask having an opening,
An irradiation range moving means for moving the irradiation range on the substrate surface by the charged particles passing through the opening on the substrate surface is provided.

The irradiation range moving means includes
A polarization control unit for controlling the polarization of the charged particle beam is provided.

The irradiation range moving means includes
A mask holding unit for holding the mask and holding the mask movably;
And a movement control unit that controls movement of the mask holding unit.

The irradiation range moving means includes
A stage for supporting the substrate and movably placing the substrate;
And a stage control unit for controlling the movement of the stage.

The exposure mask of the present invention is
In an exposure mask having an opening area that passes through a charged particle beam and irradiates the substrate surface for exposure, and forms an exposure area of a predetermined dimension on the substrate surface.
The open area is
When the exposure range on the substrate surface by the charged charged particle beam passed is fixed on the substrate surface and exposed, the exposure region of the predetermined size is smaller than the size of the opening region that will be formed. It is formed.

The exposure mask is
Used in a charged particle beam projection exposure apparatus that forms an exposure area of the predetermined dimension on the substrate surface by moving an irradiation range of a charged particle beam that irradiates the substrate surface through the opening region,
The dimensions of the open area are:
The charged particle beam projection exposure apparatus has a predetermined correspondence relationship with a movement amount for moving an irradiation range of the charged particle beam.

The exposure mask is
It is a divided mask having a portion obtained by dividing a mask pattern to be transferred onto a substrate surface as a plurality of openings.

The exposure mask is
A complementary division mask having a portion obtained by complementary division of a mask pattern to be transferred onto a substrate surface as the opening.

The method for producing an exposure mask of the present invention comprises:
In the method of manufacturing an exposure mask having an opening area that passes through a charged particle beam and irradiates and exposes the substrate surface to form an exposure area of a predetermined dimension on the substrate surface,
The open area is
When the exposure range on the substrate surface by the charged charged particle beam passed is fixed on the substrate surface and exposed, the exposure region of the predetermined size is smaller than the size of the opening region that will be formed. It is formed.

The charged particle beam projection exposure system of the present invention comprises:
Charged particles using an exposure mask having an opening area that passes through a charged particle beam to irradiate the substrate surface for exposure and forms an exposure area of a predetermined dimension on the substrate surface, and an exposure mask having the opening area In a charged particle beam projection exposure system comprising a charged particle beam projection exposure apparatus for exposing a substrate surface with a line,
The exposure mask is
From the dimension of the opening area, where the exposure area of the predetermined dimension will be formed when the opening area is exposed by fixing the irradiation range on the substrate surface by the charged particle beam that has passed therethrough. Is also formed with small dimensions,
The charged particle beam projection exposure apparatus comprises:
The exposure mask includes irradiation range moving means for moving an irradiation range on the substrate surface by the charged particle beam that has passed through the opening area on the substrate surface.

  According to the present invention, the aperture ratio of the stencil mask can be reduced. As a result, the mechanical strength of the mask can be improved. In addition, it is possible to suppress the opening of the mask from being reduced and the charged particles to repel each other due to the Coulomb force to spread the beam and reduce the resolution.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below. It demonstrates using FIGS. 1-3. In the first embodiment, the mask pattern is formed by making the mask pattern formed on the mask thinner than when the electron beam 2 is not moved relative to the wafer 9 (substrate). Then, when exposure is performed using the mask, the electron optical system condition of the electron beam 2 or the mask position or the position of the wafer 9 is changed, so that the electron beam 2 on the wafer 9 is moved and transferred to the wafer 9. A desired pattern is exposed on the wafer 9 by increasing the line width of the pattern corresponding to the amount by which the pattern is thinned.

  FIG. 1 shows a charged particle beam projection exposure apparatus 100 according to the first embodiment. In the first embodiment, an electron beam 2 is assumed as a charged particle beam. The charged particle beam projection exposure apparatus 100 changes the electron optical conditions of the electron beam 2, changes the position of the stencil mask 6, or changes the position of the wafer 9, thereby changing the electron beam 2 to the wafer 9. It is characterized in that the pattern of the stencil mask 6 transferred to the wafer 9 is thickened by moving. That is, the pattern (opening area) of the stencil mask 6 is formed with a dimension smaller by a dimension corresponding to the thickening amount than when the pattern transferred to the wafer 9 is not thickened. Therefore, the aperture ratio can be lowered and the strength of the stencil mask 6 can be increased.

  A charged particle beam projection exposure apparatus 100 includes an electron gun 1 that emits an electron beam 2, an aperture 3 that passes the electron beam 2, a condenser lens 4, a polarization controller 5 that controls the change of the electron beam 2, and a pattern that is transferred to a wafer 9. A stencil mask 6 having a mask, a mask holding unit 7 that holds the stencil mask 6, a movement control unit 8 that controls the movement of the mask holding unit 7, a wafer 9, a stage 10 on which the wafer 9 is placed, and a movement of the stage 10 are controlled. A stage control unit 11 is provided.

  FIG. 2 is a conceptual diagram for explaining the stencil mask 6 according to the first embodiment. In FIG. 2A and FIG. 2B, hatched portions are patterns (opening areas). In FIG. 2C, the hatched portion shows the pattern after exposure. A major feature of the stencil mask 6 according to the first embodiment is that it has a pattern (opening area) shown in FIG. The overall shape of the mask according to the first embodiment is the same as that of the mask shown in FIG. FIG. 2A shows a case where a desired exposure pattern is formed when exposure is performed by fixing the irradiation range on the surface of the wafer 9 by the electron beam 2 having passed through the pattern (opening area) on the surface of the wafer 9. The dimensions of the pattern (opening area) that will be shown. In addition, only the dimension of line | wire width is shown and other dimensions are abbreviate | omitted. Hereinafter, the pattern having this dimension is also referred to as an “original pattern”. That is, the “original pattern” is a desired mask pattern without moving the electron beam 2 relative to the wafer 9 without changing any of the electron optical conditions of the electron beam 2, the position of the stencil mask 6, or the position of the wafer 9. Is a mask pattern when the wafer 9 is exposed to light. FIG. 2B shows a case where a desired exposure pattern is formed when exposure is performed with the irradiation range on the surface of the wafer 9 fixed by the electron beam 2 having passed through the pattern (opening area) on the surface of the wafer 9. The pattern actually formed on the mask is shown by a smaller dimension than the pattern (opening area) that will be formed. Here, the “dimension smaller than the pattern (opening area)” may be a partial dimension of the pattern or a small dimension of the pattern. The area of the opening (opening area) of the pattern actually formed on the mask may be reduced. At the time of exposure, as shown in FIG. 2C, in accordance with the resized amount, for example, by moving the position of the stencil mask 6 vertically and horizontally with respect to the substrate, It is possible to form the same pattern (exposure area) on the wafer 9.

  In addition, the stencil mask 6 is not moved with respect to the wafer 9 but the conditions of the electron optical system of the charged particle beam projection exposure apparatus 100 are changed so that a pattern having the same line width as the “original pattern” can be formed. The charged particle beam may be moved. The means for increasing the line width will be described later.

  Note that the mask according to Embodiment 1 having the pattern shown in FIG. 2B can also be grasped as a mask manufacturing method. That is, the pattern area (opening area) is larger than the dimension of the pattern that would form a desired exposure area when the wafer 9 is exposed with the irradiation range of the electron beam 2 passed through the wafer 9 fixed. It can be grasped as an exposure mask formed with small dimensions.

  A study of reducing the aperture ratio of the pattern of the stencil mask 6 based on FIG. 2A is as follows. The line width of the “original pattern” is 200 nm and the pitch is 500 nm. When the resize amount is 40 nm on one side, the aperture ratio in the “original pattern” is 200 nm ÷ 500 nm = 0.4, and the original aperture ratio is 40%. On the other hand, since the one side is reduced by 40 nm by resizing, the aperture ratio becomes (200 nm−40 nm−40 nm) ÷ 500 nm = 0.24. As described above, the decrease in the aperture ratio reduces the Coulomb repulsive force and the spread of the electron beam (blur), and the remaining beam becomes thicker, so that the mechanical strength is improved and the fear of breakage is reduced. .

  Next, means for moving the irradiation range of the electron beam 2 on the surface of the wafer 9 on the surface of the wafer 9 will be described.

  First, the irradiation range of the electron beam 2 on the surface of the wafer 9 can be moved by polarizing the electron beam 2 by the polarization controller 5 shown in FIG. FIG. 3 is a conceptual diagram showing a state in which the electron beam 2 is changed by the polarization controller 5. FIG. 3 shows a part of a cross section of the stencil mask 6. Since the irradiation angle of the electron beam 2 to the wafer 9 is changed by the polarization controller 5, the irradiation range can be moved. An electron beam 2 indicated by a broken line indicates before polarization. The solid electron beam 2 shows the state after polarization. The line width can be increased by the amount of thickening due to the difference in the incident angle due to the polarized light.

  In addition, means for moving the irradiation range of the electron beam 2 onto the wafer 9 by moving the mask holding unit 7 will be described. The mask holder 7 that holds the stencil mask 6 is installed so as to be movable with respect to the charged particle beam projection exposure apparatus 100. That is, the mask holding unit 7 can move in a substantially horizontal direction H and a substantially vertical direction V with respect to the surface of the wafer 9. The stencil mask 6 held by the mask holding unit 7 can be moved along with the movement of the mask holding unit 7, thereby moving the irradiation range of the electron beam 2 onto the wafer 9. The movement control unit 8 controls the movement of the mask holding unit 7. The “movement information” of the mask holding unit 7 is input in advance to the movement control unit 8, and the movement control unit 8 controls the movement of the mask holding unit 7 based on this input information, and the surface of the wafer 9. A desired pattern can be transferred to the substrate. Here, the “information regarding movement” is the dimension of the “original pattern”, the dimension of the pattern actually formed on the mask, or the resize amount.

  Further, by moving the position of the wafer 9, the irradiation range of the electron beam 2 onto the wafer 9 can be moved. The stage 10 on which the wafer 9 is placed is movably installed with respect to the charged particle beam projection exposure apparatus 100. That is, the stage 10 can move in a substantially horizontal direction H and a substantially vertical direction V with respect to the wafer 9 surface. By moving the wafer 9 placed on the stage 10 as the stage 10 moves, the irradiation range of the electron beam 2 on the wafer 9 can be moved. The stage controller 11 controls the movement of the stage 10. Information relating to the movement of the stage 10 is input to the stage control unit 11, and the stage control unit 11 controls the movement of the stage 10 based on this input information to transfer a desired pattern onto the surface of the wafer 9. . The “information regarding movement” is the same as that described above.

  Further, the focus of the electron beam 2 that irradiates the surface of the wafer 9 may be blurred. Focus blurring may be realized by electro-optical conditions, or may be realized by moving the mask holding unit 7 or the stage 10 in a substantially vertical direction V.

  Although the means for moving the irradiation range of the electron beam 2 onto the wafer 9 has been described above, the amount of movement by the moving means and the size of the pattern (opening area) of the stencil mask 6 are naturally related. For example, when a pattern is transferred to the wafer 9 at 1: 1, the amount of resize is the amount of movement. For example, in FIG. 2B, 40 nm is the amount of movement (the amount of movement to the front, rear, left and right). In addition, in the case of transfer with a reduction of ¼, 10 nm, which is a quarter of the resize amount, is a movement amount (amount of movement in the front / rear and left / right directions).

  As described above, the charged particle beam projection exposure apparatus 100 according to the first embodiment moves various irradiation ranges on the wafer 9 surface by the electron beam 2 passing through the opening of the stencil mask 6 on the wafer 9 surface. With the means, the electron beam 2 can be thickened on the wafer 9 surface. For this reason, it is possible to provide a mask having a small aperture and a small aperture ratio, and it is possible to improve the strength of the mask and the resolution with suppressed Coulomb repulsion.

  As described above, since the stencil mask 6 according to Embodiment 1 is formed by narrowing the opening, the strength of the mask can be improved by reducing the aperture ratio. Moreover, a yield can be improved with the improvement in strength. Furthermore, the spread of the electron beam 2 due to Coulomb repulsion can be suppressed.

  As described above, according to the first embodiment, in charged particle beam projection exposure, a mask is manufactured by thinning a mask pattern used for exposure, and when exposure is performed using the mask, the electron of the charged particle beam projection exposure apparatus is used. By changing the optical system condition or the mask position, the charged particle beam is moved with respect to the substrate, and the line width of the pattern transferred to the substrate is increased.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIG. The second embodiment is a case where a pattern to be transferred has a so-called complementary division problem.

  FIG. 4A shows an “original pattern” to be formed on the mask. 4A, FIG. 4B, and FIG. 4C all show patterns of openings formed in the mask by hatching portions. When this “original pattern” is subjected to complementary division, the patterns are distributed to the respective complementary masks according to the line width of the “original pattern”. FIG. 4B shows the pattern of the complementary mask on the thin side, and FIG. 4C shows the pattern of the complementary mask on the thick side. The resize amount is determined according to the distribution condition (line width) for complementary division. In this example, the masks on the thin side and the thick side are distributed by complementary division depending on whether it is less than 200 nm. That is, 200 nm or more is “thick”, and less than 200 nm is “thin”. In this example, the resize amount is 0 nm (no resize) on the thin side, and 40 nm (one side) on the thick side. A mask is manufactured using the data thus created. When exposure is performed using this mask, the amount of resizing in which complementary divided region is input as additional information to the charged particle beam projection exposure apparatus 100, and exposure is performed by fattening according to the input conditions. To do. For example, it is input as additional information to the polarization controller 5, the movement controller 8, or the stage controller 11 in FIG. Note that the way of thickening at the time of exposure is the same as in the first embodiment.

  The above is for complementary division, but the amount by which the mask pattern is thinned is determined for each divided mask in charged particle beam projection exposure according to the line width of the pattern included in the divided mask, and the mask is used. The amount of change of the electron optical system condition of the charged particle beam or the mask position at the time of exposure may be changed for each divided mask.

  As described above, in the second embodiment, when the complementary division is performed, the resize amount is determined by distributing the pattern to each complementary mask according to the line width of the “original pattern”. Therefore, a pattern with a large line width has a large resizing amount and can reduce a large aperture ratio. In addition, since the fine resizing can be performed, the aperture ratio can be efficiently reduced.

  As described above, in the second embodiment, when the complementary division is performed, the resize amount is determined by distributing the pattern to each complementary mask according to the line width of the “original pattern”. Therefore, a pattern with a narrow line width may not require resizing, and the resizing efficiency can be improved.

  As described above, in the second embodiment, for each divided mask, the thinning amount is determined for each divided mask according to the line width of the pattern included in the divided mask, and the determined thinning amount (resizing amount). Corresponding to the above), the above-described means is used for the exposure. Therefore, as in the case of complementary division, when the division mask pattern is thick, a large aperture ratio can be reduced. Further, when the division mask pattern is thin, resizing may not be necessary, and efficiency can be improved.

  As described above, in the second embodiment, the amount by which the mask pattern is thinned is determined according to the line width of the pattern to which the mask pattern is distributed during complementary division, and charged particle beams are used when exposure is performed using the mask. The amount of changing the electron optical system condition or the mask position is also changed according to the designation at the time of complementary division.

  As described above, in the second embodiment, a mask pattern used for exposure is thinned to manufacture a mask, and when exposure is performed using the mask, the electron optical system conditions of the charged particle beam projection exposure apparatus or the mask position or By changing the substrate position, the line width of the pattern transferred to the substrate is increased. Here, as means for determining the amount of thinning of the mask pattern and the amount of thickening at the time of exposure (electro-optical system condition or mask position change amount (movement amount) or substrate change amount (movement amount)), for example, There are three types. First, all the patterns in the mask are uniformly thinned, and are uniformly thickened by the above-described means at the time of exposure. Second, the amount of thinning is determined according to the line width of the pattern to be distributed during complementary division, and is thickened by the above-described means at the time of exposure corresponding to the determined amount of thinning. Third, the thinning amount is determined for each divided mask in accordance with the line width of the pattern included in the divided mask, and thickened by the above-described means at the time of exposure corresponding to the determined thinning amount. It is to let you.

1 is a diagram showing a charged particle beam projection exposure apparatus 100 according to Embodiment 1. FIG. (A) And (b) is a figure which shows the opening part in a stencil mask. (C) is a figure which shows the pattern exposed on the wafer. It is a figure which shows the polarization with respect to the board | substrate of an electron beam. (A) shows a pattern to be subjected to complementary division. (B) shows the complementary pattern on the thin side that is complementary-divided. (C) shows the complementary pattern on the thick side after resizing. It is sectional drawing of the conventional stencil mask. (A) And (b) And (c) is a figure which shows the prior art example which has a complementary division | segmentation problem.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electron gun, 2 Electron beam, 3 Aperture, 4 Lens, 5 Polarization control part, 6 Stencil mask, 7 Mask holding part, 8 Movement control part, 9 Wafer, 10 stage, 11 Stage control part, 12 Pattern opening, 13 Membrane , 14 Beam, 15 Support substrate part, 100 Charged particle beam projection exposure apparatus.

Claims (10)

In a charged particle beam projection exposure apparatus that exposes a substrate surface with a charged particle beam using a mask having an opening,
A charged particle beam projection exposure apparatus comprising an irradiation range moving means for moving an irradiation range on a substrate surface by charged particles passing through the opening on the substrate surface. The irradiation range moving means includes
The charged particle beam projection exposure apparatus according to claim 1, further comprising a polarization controller that controls polarization of the charged particle beam. The irradiation range moving means includes
A mask holding unit for holding the mask and holding the mask movably;
The charged particle beam projection exposure apparatus according to claim 1, further comprising a movement control unit that controls movement of the mask holding unit. The irradiation range moving means includes
A stage for supporting the substrate and movably placing the substrate;
The charged particle beam projection exposure apparatus according to claim 1, further comprising: a stage control unit that controls movement of the stage. In an exposure mask having an opening area that passes through a charged particle beam and irradiates the substrate surface for exposure, and forms an exposure area of a predetermined dimension on the substrate surface.
The open area is
When the exposure range on the substrate surface by the charged charged particle beam passed is fixed on the substrate surface and exposed, the exposure region of the predetermined size is smaller than the size of the opening region that will be formed. An exposure mask characterized by being formed. The exposure mask is
Used in a charged particle beam projection exposure apparatus that forms an exposure area of the predetermined dimension on the substrate surface by moving an irradiation range of a charged particle beam that irradiates the substrate surface through the opening region,
The dimensions of the open area are:
6. The exposure mask according to claim 5, wherein the charged particle beam projection exposure apparatus has a predetermined correspondence relationship with a movement amount for moving an irradiation range of the charged particle beam. The exposure mask is
7. The exposure mask according to claim 5, wherein the exposure mask is a divided mask having a portion obtained by dividing a mask pattern to be transferred onto a substrate surface into a plurality of openings. The exposure mask is
7. The exposure mask according to claim 5, wherein the exposure mask is a complementary division mask having a portion obtained by complementary division of a mask pattern to be transferred onto a substrate surface as the opening. In the method of manufacturing an exposure mask having an opening area that passes through a charged particle beam and irradiates and exposes the substrate surface to form an exposure area of a predetermined dimension on the substrate surface,
The open area is
When the exposure range on the substrate surface by the charged charged particle beam passed is fixed on the substrate surface and exposed, the exposure region of the predetermined size is smaller than the size of the opening region that will be formed. A method for producing an exposure mask, which is formed. Charged particles using an exposure mask having an opening area that passes through a charged particle beam to irradiate the substrate surface for exposure and forms an exposure area of a predetermined dimension on the substrate surface, and an exposure mask having the opening area In a charged particle beam projection exposure system comprising a charged particle beam projection exposure apparatus for exposing a substrate surface with a line,
The exposure mask is
From the dimension of the opening area, where the exposure area of the predetermined dimension will be formed when the opening area is exposed by fixing the irradiation range on the substrate surface by the charged particle beam that has passed therethrough. Is also formed with small dimensions,
The charged particle beam projection exposure apparatus comprises:
A charged particle beam projection exposure system comprising irradiation range moving means for moving an irradiation range on the substrate surface by the charged particle beam having passed through the opening area by the exposure mask.

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