JP2005148634A - Method for drawing mask and mask drawing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask drawing apparatus which can draw in a short time and to provide a method for generating the data for controlling the drawing apparatus. <P>SOLUTION: A mask drawing apparatus 100 having a digital mirror device (DMD) is used, in which UV light L13 reflected by the DMD 101 passes a reduction projection optical system 104 comprising lenses 103a, 103b to be projected onto a microlens array 105. The UV light L14 is split into a large number of thin beams by the microlens array 105 and converged into the respective pinholes in a pinhole plate 106. The images on the exiting plane of the respective pinholes in the pinhole plate 106 are projected into a pattern as a collection of a large number of spots onto a mask substrate 109 by a reduction projection optical system 108 comprising lenses 107a, 107b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mask drawing apparatus used at the time of manufacturing a mask used in an exposure process at the time of manufacturing a semiconductor integrated circuit, and a data generation method for controlling the mask drawing apparatus.

  In general, in order to create a mask (sometimes called a reticle) that is used during the manufacture of a semiconductor integrated circuit, the surface of a quartz plate or the like that serves as a mask substrate is exposed in a pattern corresponding to a target circuit pattern. It is necessary to attach a chromium film that shields light. The chromium film and the like are formed by pattern exposure, and an electron beam mask drawing apparatus using an electron beam (hereinafter abbreviated as an EB drawing apparatus) is widely used as a general apparatus that draws and exposes the pattern. It is used.

  As one of the problems in mask drawing, the amount of mask pattern information becomes enormous in order to cope with semiconductors that are highly integrated and miniaturized year by year. It is possible to reach tens to hundreds of hours per mask. A general EB drawing apparatus 200 has a configuration shown in a simplified manner in FIG. 5. An electron beam emitted from an electron gun 201 is spread by an electron lens 202 a, irradiated to an aperture 203, and passed therethrough. The mask substrate 204 is irradiated with the electron beam deflected by the electron lens 202b. In order to shorten the drawing time, a technique is used in which a plurality of apertures 203 having holes of various shapes are used to collectively expose specific shapes in the drawing pattern.

  However, when drawing using apertures in this way, mask data is created from design data as shown in FIG. 4, while EB drawing taking into account the shape and type of the aperture based on the mask data. Since it is necessary to generate device control data and a calculation with a complicated algorithm is required for this purpose, the generation of the EB drawing device control data takes several hours to 10 hours. .

  An object of the present invention is to provide a mask drawing apparatus capable of drawing a mask in a shorter time than an EB drawing apparatus and a method for generating data for controlling the drawing apparatus.

  In order to achieve the above object, in the present invention, mask drawing is performed using a pattern projection apparatus using a two-dimensional array of light control elements, and control data for the pattern projection apparatus for performing the mask drawing is obtained. (Hereinafter referred to as frame data) is directly generated from semiconductor design data. As the two-dimensional array of light control elements, a micromirror device or an array of self-luminous devices are suitable. In a mask drawing apparatus using a pattern projection apparatus using these two-dimensional array of light control elements (hereinafter referred to as a mask drawing apparatus using a two-dimensional light control element), a large number of light rays are projected onto a mask substrate. Since a collection of many minute points is formed on the substrate, a mask pattern of any shape can be drawn.

  Therefore, unlike the case of the EB drawing apparatus, drawing data in consideration of a polygon having a specific shape is not necessary, so that the total mask drawing time can be greatly shortened.

  In addition, as a configuration of a mask drawing apparatus using a two-dimensional light control element, a micromirror device is used for the two-dimensional light control element, and a light beam traveling from each micromirror of the micromirror device is passed through a microlens to form a spot. Since the pixel of light projected onto the mask substrate is rounded, diagonal lines can be drawn without being jagged. In this regard, since the micromirror is usually a square, the mask drawing apparatus having a configuration in which the micromirror device is simply reduced has a problem that oblique lines cannot be drawn cleanly.

  According to the mask drawing apparatus and the data generation method for controlling the mask drawing apparatus of the present invention, the work time from when the mask data is completed from the design data to when the mask is actually drawn, compared to the case of using the EB drawing apparatus. Can be shortened by more than 10 hours.

  Furthermore, in the defect inspection process in the mask production based on the present invention, a method of directly comparing the produced mask image with the mask data can be taken. That is, conventionally, a method of comparing a mask image with EB data is generally used. However, since the EB data is not necessary in the mask drawing process in the present invention, the mask image can be directly compared with the mask data. According to this, since the mask data is the data closest to the shape of the mask pattern, the comparison algorithm can be simplified and the inspection time can be shortened compared with the case where the EB data and the mask image data are compared. In addition, the cost of the included mask inspection system can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a mask drawing apparatus 100 as an embodiment of the present invention. In the mask drawing apparatus 100, a digital mirror device (hereinafter abbreviated as DMD) is used as a two-dimensional array of light control elements capable of forming an arbitrary pattern. Ultraviolet light L11, which is exposure light from a light source (not shown), is incident on the mirror 102, and the reflected ultraviolet light L12 is incident on the surface of the DMD 101. Here, the size of each micromirror in the DMD 101 is 14 microns per side. The ultraviolet light L13 reflected by the DMD 101 (used for drawing) passes through the reduction projection optical system 104 composed of the lenses 103a and 103b, and is magnified by about 1.43 times, and the microlenses are formed at a pitch of about 20 microns. The image is projected onto the microlens array 105 arranged side by side. The reduction projection optical system 104 is simply shown as a two-lens configuration, but it is actually preferable to use a large number of lenses in order to suppress aberrations, for example, for an i-line exposure apparatus. It is preferable to use a reduction projection optical system having a magnification of 1/5. The microlens array 105 divides the ultraviolet light L14 into a large number of thin light beams, which are condensed on each pinhole in the pinhole plate 106, respectively. However, the pinhole plate 106 is not necessarily a plate having holes, and a light-shielding film such as Cr having a large number of holes on a glass plate so that the irradiated laser light can be divided into a large number of light beams. In the present invention, these are simply referred to as pinhole plates.

  The light image on the exit surface of each pinhole of the pinhole plate 106 is pattern-projected on the mask substrate 109 by the reduction projection optical system 108 composed of the lenses 107a and 107b. The magnification of the reduction projection optical system 108 is 1/5 here. Therefore, the center interval of each spot in the spot aggregate projected onto the mask substrate 109 is 0.4 microns.

  A drawing technique by the mask drawing apparatus 100 of the present embodiment is shown in FIG. On the mask substrate 109, the projection area of the pinhole plate 106 is projected as an aggregate of spots as 121. Therefore, the exposed region 122 is formed by scanning the mask substrate 109 at an angle (actually moving the mask substrate 109). An arbitrary pattern can be exposed on the mask substrate 109 by performing ON / OFF control of each micromirror in the DMD 101 during this scan. At this time, an ON / OFF control command (that is, control data for the mask drawing apparatus 100) of each micromirror is transmitted from the mask drawing apparatus control data 150. As this data, ON / OFF data corresponding to the total number of micromirrors in the DMD 101 is sent 10,000 times per second (that is, the frame speed of the DMD 101, which is operating at 10,000 Hz here). .

  As described above, when pattern exposure is performed on the mask substrate 109 by the mask drawing apparatus 100, a pattern is formed while moving an aggregate of round spots (fine spots) as in the projection region 121 of the pinhole plate 106. Therefore, since the special shape is not pattern projected unlike the EB drawing apparatus, the control data of the mask drawing apparatus 100 can be generated directly from the mask data as shown in FIG. It was.

It is a figure which shows the structure of the mask drawing apparatus 100 of this invention. It is a figure explaining drawing operation | movement using the mask drawing apparatus 100 shown by FIG. It is a flowchart explaining the data production | generation procedure for the mask drawing apparatus control of this invention. It is a flowchart explaining the data production | generation for control in the case of using the conventional EB drawing apparatus. It is a figure explaining the structure of the conventional EB drawing apparatus.

Explanation of symbols

100 Mask Drawing Device 101 DMD
102 Mirrors 103a, 103b, 107a, 107b Lenses 104, 108 Reduction projection optical system 105 Micro lens array 106 Pinhole plate 109 Mask substrate 121 Projection region 122 of pinhole plate 106 Exposed region 200 EB drawing apparatus 201 Electron gun 202a, 202b Electron lens 203 Aperture 204 Mask substrate

Claims (8)

  A mask drawing method for use in a pattern projection apparatus using a two-dimensional array of light control elements, wherein the frame data for the light control elements is directly generated from design data.   2. The mask drawing method according to claim 1, wherein the two-dimensional array of light control elements are individually controlled by the frame data, and the controlled light beam is drawn on a mask.   3. The mask drawing method according to claim 2, wherein the light control element is constituted by a two-dimensional array of micromirror devices, and each micromirror is individually controlled to be turned on and off by the frame data.   3. The mask drawing method according to claim 2, wherein the controlled light beam from the light control element is projected onto the mask through a microlens.   The light control obtained from the design data in a mask drawing apparatus comprising a micromirror device as a two-dimensional array of light control elements and a microlens that allows light traveling from each micromirror in the micromirror device to pass therethrough A mask drawing apparatus characterized by storing frame data for an element and controlling the micromirror device based on the frame data.   6. The mask drawing apparatus according to claim 5, wherein the micromirrors constituting the micromirror device are ON / OFF controlled by the frame data.   7. The mask drawing apparatus according to claim 6, wherein the light beam from the microlens is projected onto the mask through a pinhole plate. 8. The mask drawing apparatus according to claim 7, wherein a projection area on the mask by the pinhole plate is inclined with respect to the mask.

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