JP2005101405A - Dummy pattern information preparing device, pattern information preparing device, mask, exposure device, method of manufacturing mask, method of preparing dummy pattern information, program, and computer-readable recording medium recording the program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a dummy pattern arrangeable in accordance with low (rough) pattern area density as much as possible by making the pattern area density uniform by reducing the offset of the density. <P>SOLUTION: A dummy pattern information preparing device is provided with a storage 170 which stores pattern information to be arranged on a mask, a virtually arranging section 110 which virtually arranges a prescribed area on the mask, and a moving section 120 which moves the virtually arranged prescribed area by a prescribed distance so that the area overlaps the area of the last time. The device is also provided with a calculator 130 which calculates the area density in the prescribed area of a pattern drawn by the stored pattern information whenever the prescribed area is moved based on the stored pattern information, and a preparing section 140 which prepares dummy pattern information to be arranged on the mask based on the calculated area density. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dummy pattern information generation apparatus, a pattern information generation apparatus, a mask, an exposure apparatus, a mask creation method, a dummy pattern information generation method, a program, and a computer-readable recording medium on which the program is recorded. In particular, the present invention relates to a method for uniformizing the pattern area density of a mask used in a charged particle beam projection exposure method, a mask using this method, a mask creation method, and a method for manufacturing a semiconductor device. The present invention also relates to a method of forming a pattern by combining charged particle beam projection exposure and other exposure on the same resist layer, and a dummy pattern forming method.

  In recent years, in order to manufacture semiconductor integrated circuits that are increasingly miniaturized, a new exposure technique replacing the ultraviolet exposure technique has been demanded, and charged particle beam projection exposure, in particular, electron beam projection exposure technique, has attracted attention. The stencil type and the scattering membrane type are known as masks used in this electron beam projection exposure technology, but since both structures use a thin film substrate, if there is a bias in the circuit pattern arrangement, its own stress Easily distorted.

  Even in the process of flattening a semiconductor substrate used to create a semiconductor integrated circuit (mainly chemical mechanical polishing is used), if there is a bias in the layout of the circuit pattern, it cannot be uniformly flattened. Various methods for arranging the patterns have been proposed (see, for example, Patent Documents 1 to 4).

On the other hand, when a stencil mask is used, it is impossible to form a donut-like pattern, so one pattern is divided into two complementary patterns (complementary division), and two exposures are required with two stencil masks. It is. However, since this complementary exposure is disadvantageous in terms of throughput (processing amount per unit time), mask area, mask intensity, etc., the same layer mix-and-match that combines charged particle beam projection exposure and conventional ultraviolet exposure ( Hereinafter, the same layer M & M exposure has also been proposed (see, for example, Patent Document 5).
JP-A-8-160590 JP-A-10-293391 JP 2001-267321 A JP 2002-176102 A JP 2001-144001 A

  Although the above-described substrate flattening technique can be used in the charged particle beam projection exposure, the dummy pattern can be arranged only in the absence of the circuit pattern, and thus the area density deviation of the region where the circuit pattern exists cannot be corrected. This is because in charged particle beam projection exposure, it is necessary to make the pattern area density uniform even when only a part of a narrow range is seen rather than flattening the entire substrate.

  If dummy patterns are arranged in accordance with a dense pattern area density, the amount of charged particle beams that pass through the mask increases, and the exposure beam blur due to Coulomb repulsion between charged particle beams increases. That is, the resolution is reduced. Further, since the strength of the mask also decreases, it is desirable to arrange dummy patterns in accordance with the lowest possible (sparse) pattern area density.

  In the same layer M & M exposure described above, no proposal has been made to correct the bias of the circuit pattern arrangement of the charged particle beam projection exposure mask.

  It is an object of the present invention to make the pattern area density uneven and uniform.

  Another object of the present invention is to arrange dummy patterns in accordance with the lowest possible (sparse) pattern area density.

A dummy pattern information generating apparatus according to the present invention includes a storage unit that stores pattern information for placement on a mask,
A virtual placement unit that virtually places a predetermined area on the mask;
A moving unit that moves the predetermined area virtually arranged by the virtual arrangement unit by a predetermined distance so as to overlap the previous area;
Based on the pattern information stored by the storage unit, a calculation unit that calculates the area density in the predetermined region of the pattern drawn by the pattern information every time the predetermined region is moved by the moving unit;
And a generation unit that generates dummy pattern information to be arranged on the mask based on the area density calculated by the calculation unit.

  When the dummy pattern is arranged in the center of the predetermined region moved by the moving unit, the generating unit is configured so that the area density of each predetermined region calculated by the calculating unit approaches uniformly. It is characterized by generating information.

The dummy pattern information generating device further includes:
A determination unit for determining whether the area density calculated by the calculation unit is smaller than a predetermined value;
A division unit that divides the pattern information stored by the storage unit into a plurality of pattern information when the area density is not smaller than a predetermined value as a result of the determination by the determination unit;
The moving unit moves the predetermined area virtually arranged by the virtual arrangement unit by a predetermined distance so as to overlap the previous area,
The calculation unit recalculates the area density in the predetermined region every time the predetermined region is moved by the moving unit based on any one of the plurality of pattern information divided by the dividing unit. Calculate
Based on the area density recalculated by the calculation unit, the generation unit generates dummy pattern information to be arranged on the mask together with any one of the plurality of pattern information divided by the division unit. It is characterized by generating.

A dummy pattern information generating apparatus according to the present invention includes a storage unit that stores pattern information for placement on a mask,
A virtual reduction unit that virtually reduces the line width of the pattern by a predetermined size based on the pattern information stored by the storage unit;
As a result of the virtual reduction by the virtual reduction unit, a calculation unit for calculating the area density of the pattern that has disappeared,
And a generation unit that generates dummy pattern information to be arranged on the mask together with the pattern to be eliminated based on the area density calculated by the calculation unit.

The dummy pattern information generating device further includes:
A virtual placement unit that virtually places a predetermined area on the mask;
A moving unit that moves a predetermined area virtually arranged by the virtual arranging unit by a predetermined distance;
The calculation unit calculates the area density in the predetermined region of the pattern that is supposed to disappear each time the predetermined region is moved by the moving unit,
The generation unit generates the dummy pattern information so that the area density for each predetermined region calculated by the calculation unit approaches uniformly.

  The pattern information generation apparatus according to the present invention generates pattern information for placement on a mask based on the dummy pattern information generated by the dummy pattern information generation apparatus.

  The mask according to the present invention is produced based on the pattern information generated by the pattern information generating apparatus.

  An exposure apparatus according to the present invention is characterized in that a sample is exposed using the mask.

  The mask creating method according to the present invention is characterized by comprising the following steps.

(1) A step of dividing a circuit pattern by a calculation window of a predetermined size,
(2) a first calculation step of calculating a pattern area density in each calculation window divided by the step of dividing;
(3) a step of determining whether to perform in-layer mix and match (M & M) exposure as a result of the calculation by the first calculation step;
(4) A step of carving out a pattern to be exposed in the same layer M & M exposure when carrying out the same layer M & M exposure according to the step to be determined.
(5) a second calculation step of calculating, for each calculation window, a pattern area density of a pattern that is not exposed by the same layer M & M exposure that is cut by the step of cutting
(6) a first calculation step of calculating a target pattern area density for averaging based on a pattern area density of a pattern not exposed by the same layer M & M exposure calculated by the second calculation step;
(7) a second calculation step of calculating a prohibited area in which a dummy pattern should not be generated with respect to a pattern that is not exposed by the same layer M & M exposure that is cut by the cutting step;
(8) Generation / placement of dummy patterns is performed for each correction window on the basis of the target pattern area density for averaging calculated in the first calculation step and the prohibited area calculated in the second calculation step. Process,
(9) a third calculation step of calculating the pattern area density for each calculation window with respect to the pattern in which the dummy pattern is generated / placed by the step of performing the generation / placement of the dummy pattern for each correction window;
(10) A step of determining whether or not the area density calculated by the third calculation step is within a predetermined range.

A dummy pattern information generation method according to the present invention includes a storage step of storing pattern information for placement on a mask in a storage device,
A virtual placement step of virtually placing a predetermined area on the mask;
A moving step of moving the predetermined region virtually arranged by the virtual arrangement step by a predetermined distance so as to overlap the previous region;
Based on the pattern information stored in the storage device by the storage step, a calculation step of calculating the area density in the predetermined region of the pattern drawn by the pattern information every time the predetermined region is moved by the moving step;
And a generation step of generating dummy pattern information for placement on the mask based on the area density calculated by the calculation step.

A dummy pattern information generation method according to the present invention includes a storage step of storing pattern information for placement on a mask in a storage device,
A virtual reduction step of virtually reducing the line width of the pattern by a predetermined size based on the pattern information stored in the storage device by the storage step;
As a result of the virtual reduction by the virtual reduction process, a calculation process for calculating the area density of the pattern that has disappeared,
And a generation step of generating dummy pattern information to be arranged on the mask together with the pattern to be eliminated based on the area density calculated by the calculation step.

A computer-readable recording medium according to the present invention includes a storage process for storing pattern information for placement on a mask in a storage device,
Virtual placement processing for virtually placing a predetermined area on the mask;
A movement process for moving the predetermined area virtually arranged by the virtual arrangement process by a predetermined distance so as to overlap the previous area;
Based on the pattern information stored in the storage device by the storage process, a calculation process for calculating the area density in the predetermined area of the pattern drawn by the pattern information every time the predetermined area is moved by the movement process;
A program for causing a computer to execute generation processing for generating dummy pattern information to be arranged on the mask based on the area density calculated by the calculation processing or the program is recorded.

A computer-readable recording medium according to the present invention includes a storage process for storing pattern information for placement on a mask in a storage device,
A virtual reduction process for virtually reducing the line width of the pattern by a predetermined size based on the pattern information stored in the storage device by the storage process;
As a result of virtual reduction by the virtual reduction process, a calculation process for calculating the area density of the pattern that has disappeared;
A program for causing a computer to execute generation processing for generating dummy pattern information to be arranged on the mask together with the pattern to be eliminated based on the area density calculated by the calculation processing or the program Characterized by recording.

  According to the present invention, since the pattern area density of the charged particle beam projection exposure mask is made uniform, the positional accuracy is improved.

  Further, since the pattern area density of the charged particle beam projection exposure mask is made uniform, proximity effect correction is unnecessary or reduced, and the line width accuracy of the mask and the transfer result is improved.

  Further, since the area density of the openings of the charged particle beam projection exposure mask is made uniform, the mechanical strength of the mask is improved.

  In addition, since the large opening can be eliminated in the charged particle beam projection exposure mask, damage to the mask can be prevented.

  Further, since the pattern area density of the mask for charged particle beam projection exposure is made uniform with a low (sparse) value, the amount of beam blur caused by Coulomb repulsion between charged particle beams can be reduced.

  Further, the manufacturing cost of the charged particle beam projection exposure mask can be reduced.

  Further, it is not necessary to generate a dummy pattern for other processes such as CMP (Chemical Mechanical Polishing).

  As described below, the present embodiment relates to a method for uniformizing the pattern area density of a mask used in a charged particle beam projection exposure method, a mask, a mask creation method, and a semiconductor device manufacturing method, and a dummy pattern formation method. And a method of forming a pattern by combining charged particle beam projection exposure and other exposure on the same resist layer.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating an appearance of the information generation apparatus according to the first embodiment.

  In FIG. 1, a CRT (Cathode Ray Tube) display device 41, a keyboard (K / B) 42, a mouse 43, a compact disk device (CDD) 86, a printer device 87, and a scanner device 88 include an information generation device (dummy pattern information generation). A personal computer (PC) 100 as an apparatus and an example of a dummy pattern information generation apparatus). An example of the PC 100 is a CAD device used for pattern circuit design.

  FIG. 2 is a hardware configuration diagram of the information generation apparatus according to the first embodiment.

  In FIG. 2, a CPU (Central Processing Unit) 37 that executes a program includes a ROM (Read Only Memory) 39 (an example of a storage device) and a RAM (Random Access Memory) 40 (an example of a storage device) via a bus 38. CRT display device 41, K / B 42, mouse 43, communication board 44, FDD (Flexible Disk Drive) 45, magnetic disk device 46 (which is an example of a storage device), CDD 86, printer device 87, scanner device 88 Connected with. The communication board 44 is connected to another device or the network 30.

  Here, the network 30 may be, for example, the Internet, a LAN (local area network), or a WAN (wide area network) such as ISDN.

  The magnetic disk device 46 stores an operating system (OS) 47, a window system 48, a program group 49, and a file group 50. The program group 49 is executed by the CPU 37, the OS 47, and the window system 48.

  Moreover, in the following description, what was described as “to part” in the description of each embodiment can be configured by a program that can be operated by a computer in part or in whole. These programs can be created in C language, for example. Alternatively, HTML, SGML, or XML may be used. Alternatively, the screen display may be performed using JAVA (registered trademark). Or what was demonstrated as "-part" in description of each embodiment can also be comprised by a part or all hardware.

  When configured by a program, the program group stores a program to be executed by what has been described as “˜unit” in the description of each embodiment.

  Also, what has been described as “˜unit” in the description of each embodiment may be realized by firmware stored in a ROM. Alternatively, it may be implemented by software, hardware, or a combination of software, hardware, and firmware.

  The program for implementing each of the above embodiments includes, as an example of a storage device, a magnetic disk device, an FD (Flexible Disk), an optical disc, a CD (Compact Disc), an MD (Mini Disc), a DVD (Digital Versatile Disk), and the like. You may memorize | store using the recording apparatus by other recording media.

  The output unit may use an output device such as a CRT display device, other display devices, or a printer device.

  FIG. 3 is a block diagram of the information generating apparatus according to the first embodiment.

  In FIG. 3, a PC 100 as an information generation device includes a dummy pattern information generation device 200 and a pattern information generation device 300.

  The dummy pattern information generation apparatus 200 includes a virtual arrangement unit 110, a movement unit 120, a calculation unit 130, a generation unit 140, a determination unit 150, a division unit 160, a storage unit 170, a virtual reduction unit 180, an input unit 190, and an output unit 195. I have.

  The pattern information generation apparatus 300 includes an input unit 310, an output unit 320, a generation unit 330, and a storage unit 340.

  FIG. 4 is a flowchart illustrating the operation of the information generation device according to the first embodiment.

  In step S (step) 401, as an input process, the input unit 190 inputs pattern information for placement on the mask.

  In S402, as a storage process, the storage unit 170 stores pattern information for placement on the mask. Alternatively, it is stored in a storage device.

  In S403, as a virtual placement step, the virtual placement unit 110 virtually places a predetermined area on the mask. In other words, the virtual placement unit 110 divides the circuit pattern by a calculation window having a predetermined size.

  In S404, as a first movement step, the moving unit 120 moves the predetermined area virtually arranged by the virtual arrangement unit 110 by a predetermined distance so as to overlap the previous area.

  In S405, as a first calculation step, the calculation unit 130, based on the pattern information stored in the storage unit 170, the pattern drawn by the pattern information every time the predetermined area is moved by the moving unit 120. The area density in a predetermined region is calculated. In other words, the calculation unit 130 calculates the pattern area density in each calculation window divided by the dividing step.

  In S406, as a first determination step, the determination unit 150 determines whether the area density calculated by the calculation unit 130 is smaller than a predetermined value. In other words, the determination unit 150 determines whether to perform the same layer mix and match (M & M) exposure as a result of the calculation by the first calculation step.

  In step S407, as a first virtual reduction process, the virtual reduction unit 180 virtually reduces the line width of the pattern by a predetermined size based on the pattern information stored in the storage unit 170. The predetermined size is, for example, 200 nm. Alternatively, the line width of a pattern that can be exposed by charged particle beam projection exposure but cannot be exposed by ultraviolet exposure is set to a predetermined size. The line width of a pattern that can be exposed by other than charged particle beam projection exposure can be made as sparse as possible by performing exposure other than charged particle beam projection exposure as much as possible.

  In S <b> 408, as a first dividing step, the dividing unit 160 determines that the pattern information stored in the storage unit 170 is a plurality of pieces of pattern information when the area density is not smaller than a predetermined value as a result of the determination by the determining unit 150. Dividing into pattern information, the plurality of pattern information is restored to the line width of the original pattern. That is, the plurality of pattern information virtually reduced by the virtual reduction unit 180 is thickened by a predetermined size. In other words, when the same layer M & M exposure is performed according to the above-described determination process, the dividing unit 160 cuts out a pattern to be exposed by the same layer M & M exposure.

  In step S409, as a second virtual reduction process, the virtual reduction unit 180 virtually reduces the line width of the pattern by a predetermined size based on the pattern information of the pattern exposed by the same layer M & M exposure divided by the division unit 160. to shrink. Here, the second virtual reduction step is performed, but the second virtual reduction step may be omitted.

  In S410, as the second division step, the division unit 160 further divides the pattern information virtually reduced by the virtual reduction unit 180 as the second virtual reduction step into a plurality of pattern information, and the plurality of pattern information is divided into the plurality of pattern information. Restores the line width of the original pattern. That is, the plurality of pattern information virtually reduced by the virtual reduction unit 180 is thickened by a predetermined size. Here, the second division step is performed, but the second division step may be omitted.

  In S411, as the second moving step, the moving unit 120 moves the predetermined area virtually arranged by the virtual arranging unit 110 by a predetermined distance so as to overlap the previous area.

  In S412, as the second calculation step, the calculation unit 130 determines that the predetermined area is generated by the moving unit 120 based on any one of the plurality of pattern information divided by the dividing unit 160. Each time it is moved, the area density in a predetermined region is recalculated. In other words, the calculation unit 130 calculates the area density of the pattern that has disappeared as a result of the virtual reduction by the virtual reduction unit 180. The calculation unit 130 calculates the area density in the predetermined region of the pattern that has disappeared each time the predetermined region is moved by the moving unit 120. In other words, the calculation unit 130 calculates, for each calculation window, the pattern area density of the pattern that is not exposed by the same layer M & M exposure that has been carved out in the carving process.

  In S413, as the first calculation step, the calculation unit 130 calculates a target pattern area density for averaging based on the pattern area density of the pattern not exposed in the same layer M & M exposure calculated in the second calculation step. To do.

  In S414, as a second calculation step, the calculation unit 130 calculates a forbidden area in which a dummy pattern should not be generated for a pattern that is not exposed in the same layer M & M exposure that has been cut in the step of cutting.

  In S415, as a generation process, the generation unit 140 generates dummy pattern information to be arranged on the mask based on the area density calculated by the calculation unit 130. When the dummy pattern is arranged at the center of the predetermined region moved by the moving unit 120, the generating unit 140 may make the area density calculated by the calculating unit 130 uniform. Dummy pattern information is generated. Based on the area density recalculated by the calculation unit 130, the generation unit 140 is a dummy for arranging the pattern information in the mask together with any one of the plurality of pattern information divided by the division unit 160. Generate pattern information. Further, the generation unit 140 generates dummy pattern information to be placed on the mask together with the pattern that has been eliminated based on the area density calculated by the calculation unit 130. In other words, the generation unit 140 generates / arranges dummy patterns based on the average target pattern area density calculated in the first calculation step and the prohibited area calculated in the second calculation step. For each correction window.

  In S416, as a third calculation step, the calculation unit 130 compares the pattern area for each calculation window with respect to the pattern in which generation / placement of the dummy pattern is performed for each correction window. Calculate the density.

  In S417, as a second determination step, the determination unit 150 determines whether or not the area density calculated by the third calculation step is within a predetermined range.

  In S418, as an output step, the output unit 195 outputs dummy pattern information for placement on the mask.

  In the present embodiment, a dummy pattern information generation method is proposed by the above steps and combinations thereof.

  The input unit 310 of the pattern information generation device 300 inputs the dummy pattern information generated by the dummy pattern information generation device 200.

  The storage unit 340 stores the input dummy pattern information. Alternatively, it is stored in a storage device.

  The generation unit 330 generates pattern information for placement on the mask based on the input dummy pattern information.

  The output unit 320 outputs pattern information for placement on the generated mask.

  As described above, the area density of the circuit pattern is moved by moving the calculation area of the pattern area density of a predetermined size in a predetermined step so that the area density of the circuit pattern of the mask used for charged particle beam projection exposure is uniform. And a dummy pattern is arranged.

  The length of the predetermined region virtually arranged in a square shape in the virtual arrangement step of S403 in FIG. 4 and the predetermined distance in the first and second movement steps of S404 and S411 may be the same, but the predetermined distance is predetermined It is desirable to be smaller than the length of the region (the length of one side of the square region). In other words, the calculation area, which is an example of the predetermined area, and the step amount, which is an example of the predetermined distance, may be the same, but are usually different. A smaller step amount is desirable. In the charged particle beam projection exposure mask, it is desirable that the pattern area density is low and constant in order to avoid beam blur due to Coulomb repulsion and deformation of the mask due to the pattern opening, and the smaller constant region is desirable. . Or it is desirable that it is not so large. For example, even if the area density is 10% in a calculation area of 100 μm □ (corner), if there is a pattern concentration of 50% in the inner 10 μm □, there is an adverse effect on beam blurring and mask deformation. Also, just because it is better to make the region to be constant smaller, for example, if both the calculation region and the step amount are 10 μm □, a certain 10 μm □ and the adjacent region greatly increase the position of the pattern concentration portion. Even if there is a difference, it cannot be grasped. Therefore, it is preferable that the moving unit 120 moves the predetermined area virtually arranged in a square shape by the virtual arrangement unit 110 by a predetermined distance so as to overlap the previous area.

  An area (correction window) where the generation unit 140 arranges the dummy pattern is virtually arranged in the center of the calculation area, and the size of the area is the same as the step amount. This is because if the correction windows are overlapped, it takes a plurality of times to correct. Therefore, it is desirable to make the length of one side of the correction window virtually arranged in a square shape and the step amount the same.

  The pattern area density calculation by the calculation unit 130 and the dummy pattern placement by the generation unit 140 are repeatedly performed until a predetermined convergence condition is satisfied, or are performed a predetermined number of repetitions. The predetermined convergence condition is determined according to the line width allowed for the mask.

  Further, the prohibition area for prohibiting the placement of the dummy pattern by the calculation unit 130 is generated by thickening the circuit pattern of the circuit pattern focused layer and the layer connected as a circuit by a predetermined amount.

  When a layer connected as a circuit also generates a dummy pattern, the circuit pattern of the layer connected as a circuit with the layer is also used for the prohibited area calculation.

  It is also possible to set all circuit patterns included in a specific layer as a prohibited area.

  Further, as described later, it is desirable that the generation unit 140 preferentially deforms and removes dummy patterns that are not repeatedly arranged.

  The dividing unit 160 does not expose the circuit pattern to the semiconductor substrate by only one charged particle beam projection exposure, but when performing the exposure by a plurality of exposures, among the masks used for each exposure, the charged particle beam projection exposure is performed. As for the mask used for the above, the circuit pattern is divided into masks used for each exposure so that the area density of the circuit pattern is uniform. Therefore, the determination unit 150 determines whether the area density calculated by the calculation unit 130 is smaller than a predetermined value. In other words, the dividing unit 160 divides the circuit pattern into masks used for each exposure so that the area density of the mask used for the charged particle beam projection exposure is smaller than a predetermined value. That is, the pattern of the charged particle beam projection exposure and the other exposure is classified according to the dimension of the pattern.

  In the first division step, at least one of the plurality of exposures is a charged particle beam projection exposure, but any other exposure technique such as ultraviolet exposure or electron beam direct drawing may be used for other than that. .

  In the second dividing step, an exposure pattern that is not a charged particle beam projection exposure is further divided according to the dimension of the pattern, and a small dimension pattern is formed only by an exposure that is not a charged particle beam projection exposure, A large-sized pattern may generate a dummy pattern in the charged particle beam projection exposure in that region.

  In addition, an area that is thinned by a predetermined amount from a large dimension pattern among the exposure patterns that are not charged particle beam projection exposures is excluded from the dummy pattern prohibited area.

  The above steps will be described in detail below.

  FIG. 5 is a diagram showing a calculation window and a step pitch.

  In S403 in FIG. 4, the circuit pattern is divided by a calculation window having a predetermined size. At this time, the step pitch of the window is determined independently of the size of the calculation window. The size and step pitch of the calculation window are determined from the electron optical characteristics of the charged particle beam projection exposure apparatus, the mask manufacturing process, and the required specifications. Both are generally about several um to 200 um. In FIG. 5, the calculation window size is 100 μm and the step pitch is 10 μm.

  In S405 in FIG. 4, the pattern area density in each calculation window is calculated.

  In S406 in FIG. 4, it is determined whether to perform the same layer M & M exposure from the pattern area density in each calculation window obtained in S405. If the maximum pattern area density in each calculation window and the maximum pattern area density difference between the calculation windows allowed in advance according to the line width of the pattern are determined, and a calculation window exceeding this is generated The same layer M & M exposure is performed on the entire circuit pattern. This is because if the pattern area density is large, blur due to Coulomb repulsion occurs, and if the pattern area density difference is large, the mask is distorted. In general, the pattern area with extremely high density is mostly the area where the thick wiring between circuit blocks is drawn, and the pin pad for electrical measurement and wiring outside the package. It is effective to reduce the pattern area density in the region by allocating a thick pattern (low resolution compared to particle beam projection exposure).

  In S407 and S408 in FIG. 4, when performing the same layer M & M exposure, the pattern to be exposed in the same layer M & M is separated (for example, distributed to another design layer). The sorting conditions are determined by which exposure machine and in which process the same layer M & M is performed. If a high-resolution KrF exposure machine and its process are used, for example, a pattern of 0.2 μm or more may be implemented by the same layer M & M (KrF exposure). In order to cut out a pattern of a certain size or larger, if the virtual reduction unit 180 narrows the circuit pattern by a certain size, the circuit pattern smaller than that size disappears. Then, when the circuit is divided by the dividing unit 160 and further thickened as much as the thinned one of the circuit patterns that did not disappear, the other circuit pattern that did not disappear can be restored to the original. However, the method of cutting out a pattern of a certain size or more is not limited to this, and other known means may be used.

  In S409 and S410 in FIG. 4, the divided same-layer M & M exposure patterns are further divided into two types. One type is a pattern in which a dummy pattern for charged particle beam projection exposure is not arranged in the pattern portion subjected to the same layer M & M exposure (hereinafter referred to as the same layer M & M pattern 1), and the other is a dummy pattern. This pattern is sometimes referred to as the same layer M & M pattern 2 hereinafter.

  The same layer M & M pattern 1 and the same layer M & M pattern 2 are sorted according to size. In the same layer M & M pattern 2, when a dummy pattern is arranged in the pattern area by charged particle beam projection exposure, it is necessary to change the pattern or double exposure, so there is a size lower limit, and the size is approximately It is about 1um. The same layer M & M pattern 1 is a pattern smaller than the same layer M & M pattern 2 and formed only by the same layer M & M exposure.

  FIG. 6 is a diagram showing the pattern separation for the same layer M & M exposure.

  The virtual reduction unit 180 virtually reduces (thinns) the line width of the pattern by a predetermined size based on the pattern information stored in the storage unit 170. If the circuit pattern is narrowed, the circuit pattern smaller than that size disappears. Then, when the circuit is divided by the dividing unit 160 and further thickened as much as the thinned one of the circuit patterns that did not disappear, the other circuit pattern that did not disappear can be restored to the original. Here, since it is divided twice and divided into three circuit patterns, the above operation is repeated again.

  In addition, correction of the influence of proximity effect (charged particle irradiation exposure phenomenon in the vicinity of the entrance location after the charged particle beam is exposed to the resist) caused by charged particle beam projection exposure on the same layer M & M exposure is known. (Auxiliary exposure, resizing of data on the same layer M & M exposure side, etc.) may be used.

  In S412 in FIG. 4, after assigning the circuit pattern to the M & M exposure in the same layer, the mask used for the annihilation charged particle beam projection exposure that has disappeared by thinning the circuit pattern by a certain size by the virtual reduction unit 180 For the circuit pattern for (1), the pattern area density is calculated again for each calculation window.

  With respect to S413 in FIG. 4, the target pattern for averaging the circuit pattern for the mask used for the annihilation charged particle beam projection exposure that has disappeared by thinning the circuit pattern by a certain size by the virtual reduction unit 180 The area density is calculated. The likelihood of the target pattern area density is determined in advance based on the electro-optical characteristics of the charged particle beam projection exposure apparatus, the mask manufacturing process, and the required specifications. The calculation unit 130 calculates a target pattern area density targeted by the average value of the pattern area density for each calculation window for the circuit pattern. For example, the virtual pattern reduction unit 180 may use the densest value among the pattern area density values for each calculation window of the circuit pattern that has disappeared as the target pattern area density.

  In S414 in FIG. 4, a prohibited area where a dummy pattern should not be generated is calculated. A pattern area obtained by subtracting an area where dummy generation is possible by M & M exposure in the same layer from the original circuit pattern and the design layer pattern that is in electrical contact with the target design layer. The amount of the forbidden area around the area is determined by a dummy pattern so that a defect such as a short circuit does not occur due to the dummy pattern.

  As described above, since a dummy pattern may be arranged in the region of the same layer M & M pattern 2, the region is not a dummy pattern prohibited region. At this time, the distance from the pattern end to be excluded from the prohibited area is determined from the alignment accuracy of the charged particle beam projection exposure and the same layer M & M exposure, the amount of pattern thickening when exposed from both, and the like. A series of operations is shown in FIG.

  FIG. 7 is a diagram illustrating generation of a prohibited area of a dummy pattern.

  FIG. 7 shows circuit information of the element isolation layer, the gate layer, and the contact layer. A predetermined amount is virtually enlarged (fat) for each layer information. Then, the sum of all the related layers is taken, and the region of the same layer M & M pattern 2 that is a pattern for the same layer M & M exposure in which a dummy pattern may be arranged is excluded from the sum of all the related layers.

  Further, it is desirable that the designer can intentionally specify the dummy pattern generation prohibited area (for example, the pattern portion of a specific design layer is a prohibited area).

  When generating dummy patterns in multiple layers that are in electrical contact, for example, when generating dummy patterns in both the source / drain formation layer and the gate formation layer, short circuit to the circuit by the dummy pattern formed in each layer, etc. It is necessary to take care not to cause defects. In this case, the problem can be solved by extending the design layer for calculating the dummy pattern generation prohibited area.

  In S415 in FIG. 4, dummy pattern generation / placement is performed for each area density correction window. The size of the correction window is the same as the step pitch of the calculation window. Unlike the calculation window, the correction windows do not overlap each other.

  FIG. 8 is a diagram showing a calculation window, a correction window, and a step pitch.

  As shown in FIG. 8, the correction window is located at the center of the calculation window. The dummy pattern is temporarily generated / placed so that the pattern area density becomes the target value over the entire calculation window, and the generation / placement of the actual pattern data is performed only within the correction window.

  A known method is used for generating / arranging the dummy patterns. For example, it has already been devised to arrange a dummy so as to ride on a certain grid within a certain window, or to incline the grid coordinate system of the dummy pattern in order to increase space utilization efficiency.

  However, in consideration of the data compression efficiency after generation of the dummy pattern, it is desirable to use the same dummy pattern as much as possible. It should also be considered not to destroy the arrangement structure as much as possible. Specifically, the area density of the dummy pattern is corrected by removing a dummy pattern having no arrangement structure such as being arranged in a narrow empty area.

  When a dummy pattern is arranged in the region of the same layer M & M pattern 2, it is necessary to modify the same layer M & M pattern 2. If the pattern shape is not adversely affected even if the dummy pattern and the same layer M & M pattern 2 are double-exposed (when the process and calculation parameters are set so as to do so), this correction is not necessary. In other cases, the dummy pattern portion is cut out from the same layer M & M pattern 2. Hereinafter, examples in which the hollowing process is performed are shown in FIGS.

  FIG. 9 is a diagram showing a dummy pattern generation target pattern.

  In the dummy pattern generation target pattern in FIG. 9, three pieces of pattern information of the same layer M & M patterns 1 and 2 and a charged particle beam layer projection pattern are shown.

  FIG. 10 is a diagram illustrating a dummy pattern prohibited area.

  As described above, a predetermined amount is virtually enlarged (thickened) for each pattern information. Then, the sum of all the related patterns is taken, and the region of the same layer M & M pattern 2 that is a pattern for the same layer M & M exposure in which the dummy pattern may be arranged is excluded from the sum of the related patterns.

  FIG. 11 is a diagram showing a charged particle beam layer projection pattern (with a dummy pattern).

  FIG. 11 shows a charged particle beam layer projection pattern in which a dummy pattern is arranged in a region other than the dummy pattern prohibited region in FIG. 10 and has a target pattern area density.

  FIG. 12 is a diagram showing the same layer M & M pattern.

  In FIG. 12, the same layer M & M pattern 2 and the same layer M & M pattern 1 in which the dummy pattern portion is hollowed out from the same layer M & M pattern 2 are shown.

  In S416 in FIG. 4, when the generation / placement of the dummy pattern is completed for the entire circuit pattern area, the pattern area density is calculated again for each calculation window.

  In S417 in FIG. 4, it is determined from the pattern area density in each calculation window obtained in S416 whether or not the circuit pattern area density is made uniform by the generation / placement of the dummy pattern. The maximum pattern area density in each calculation window and the maximum pattern area density difference between the calculation windows allowed for the mask are determined in advance, and if a calculation window exceeding this is generated, the process is re-executed from S415.

  Although complementary division is not mentioned in the present embodiment, it is desirable to determine numerical values in consideration of complementary division for calculation parameters as described above. For example, when performing the same layer M & M exposure, a calculation parameter that makes complementary division unnecessary by assigning the pattern to the same layer M & M exposure is obtained.

  As described above, according to the present embodiment, the area density of the circuit pattern is made uniform. Furthermore, the uniform pattern area density is suppressed to a value lower than that of the conventional method.

  Then, a method for equalizing the pattern area density of the mask used in the charged particle beam projection exposure method according to the present embodiment, a dummy pattern forming method, or charged particle beam projection exposure and other exposures on the same resist layer. A mask is created using pattern information generated by the method of forming a pattern by assembling. In addition, a semiconductor device is manufactured by the exposure using the mask created by the mask creating method.

As described above, the present embodiment is a charged particle beam projection exposure,
1. Calculate the area density of the circuit pattern by moving the calculation area of the pattern area density of a predetermined size in a predetermined step so that the area density of the circuit pattern of the mask used for charged particle beam projection exposure is uniform, Place a dummy pattern,
2. When a circuit pattern is not exposed to a semiconductor substrate by only one charged particle beam projection exposure, but is performed by multiple exposures, a circuit for a mask used for charged particle beam projection exposure among the masks used for each exposure The circuit pattern is divided into masks used for each exposure so that the pattern area density is uniform, and mask data is created by combining them.

1 is a diagram illustrating an appearance of an information generation device according to Embodiment 1. FIG. 2 is a hardware configuration diagram of an information generation device according to Embodiment 1. FIG. It is a block diagram of the information generation apparatus in this Embodiment 1. 6 is a diagram illustrating a flowchart for explaining the operation of the information generation apparatus according to Embodiment 1. FIG. It is a figure which shows a calculation window and a step pitch. It is a figure which shows the division | segmentation of the pattern to the same layer M & M exposure. It is a figure which shows the prohibition area | region production | generation of a dummy pattern. It is a figure which shows a calculation window, a correction | amendment window, and step pitch. It is a figure which shows a dummy pattern generation | occurrence | production target pattern. It is a figure which shows a dummy pattern prohibition area | region. It is a figure which shows a charged particle beam layer projection pattern (with a dummy pattern). It is a figure which shows the same layer M & M pattern.

Explanation of symbols

  30 network, 37 CPU, 38 bus, 39 ROM, 40 RAM, 41 CRT display device, 42 K / B, 43 mouse, 44 communication board, 45 FDD, 46 magnetic disk device, 47 OS, 48 window system, 49 program group , 50 file group, 86 compact disk device, 87 printer device, 88 scanner device, 100 PC, 110 virtual layout unit, 120 moving unit, 130 calculating unit, 140 generating unit, 150 determining unit, 160 dividing unit, 170 storage unit, 180 virtual reduction unit, 190 input unit, 195 output unit, 200 dummy pattern information generation device, 300 pattern information generation device, 310 input unit, 320 output unit, 330 generation unit, 340 storage unit.

Claims (13)

A storage unit for storing pattern information for placement on the mask;
A virtual placement unit that virtually places a predetermined area on the mask;
A moving unit that moves the predetermined area virtually arranged by the virtual arrangement unit by a predetermined distance so as to overlap the previous area;
Based on the pattern information stored by the storage unit, a calculation unit that calculates the area density in the predetermined region of the pattern drawn by the pattern information every time the predetermined region is moved by the moving unit;
A dummy pattern information generation apparatus comprising: a generation unit configured to generate dummy pattern information for placement on the mask based on the area density calculated by the calculation unit.   When the dummy pattern is arranged in the center of the predetermined region moved by the moving unit, the generating unit is configured so that the area density of each predetermined region calculated by the calculating unit approaches uniformly. 2. The dummy pattern information generating apparatus according to claim 1, wherein the information is generated. A storage unit for storing pattern information for placement on the mask;
A virtual placement unit that virtually places a predetermined area on the mask;
A moving unit that moves the predetermined area virtually arranged by the virtual arrangement unit by a predetermined distance so as to overlap the previous area;
Based on the pattern information stored by the storage unit, a calculation unit that calculates the area density in the predetermined region of the pattern drawn by the pattern information every time the predetermined region is moved by the moving unit;
Based on the area density calculated by the calculation unit, a generation unit that generates dummy pattern information for placement on the mask;
A determination unit for determining whether the area density calculated by the calculation unit is smaller than a predetermined value;
A division unit that divides the pattern information stored by the storage unit into a plurality of pattern information when the area density is not smaller than a predetermined value as a result of the determination by the determination unit;
The moving unit moves the predetermined area virtually arranged by the virtual arrangement unit by a predetermined distance so as to overlap the previous area,
The calculation unit recalculates the area density in the predetermined region every time the predetermined region is moved by the moving unit based on any one of the plurality of pattern information divided by the dividing unit. Calculate
Based on the area density recalculated by the calculation unit, the generation unit generates dummy pattern information to be arranged on the mask together with any one of the plurality of pattern information divided by the division unit. A dummy pattern information generation device characterized by generating. A storage unit for storing pattern information for placement on the mask;
A virtual reduction unit that virtually reduces the line width of the pattern by a predetermined size based on the pattern information stored by the storage unit;
As a result of the virtual reduction by the virtual reduction unit, a calculation unit for calculating the area density of the pattern that has disappeared,
A dummy pattern information generation comprising: a generation unit that generates dummy pattern information to be arranged on the mask together with the pattern to be eliminated based on the area density calculated by the calculation unit apparatus. A storage unit for storing pattern information for placement on the mask;
A virtual reduction unit that virtually reduces the line width of the pattern by a predetermined size based on the pattern information stored by the storage unit;
As a result of the virtual reduction by the virtual reduction unit, a calculation unit for calculating the area density of the pattern that has disappeared,
Based on the area density calculated by the calculation unit, a generation unit that generates dummy pattern information to be placed on the mask together with the pattern that is supposed to disappear,
A virtual placement unit that virtually places a predetermined area on the mask;
A moving unit that moves a predetermined area virtually arranged by the virtual arranging unit by a predetermined distance;
The calculation unit calculates the area density in the predetermined region of the pattern that is supposed to disappear each time the predetermined region is moved by the moving unit,
The generation unit generates dummy pattern information so that the area density for each predetermined region calculated by the calculation unit approaches uniformly.   6. A pattern information generating apparatus for generating pattern information to be arranged on a mask based on the dummy pattern information generated by the dummy pattern information generating apparatus according to claim 1.   A mask created based on the pattern information generated by the pattern information generating apparatus according to claim 6.   An exposure apparatus that exposes a sample using the mask according to claim 7. A mask making method characterized by comprising the following steps;
(1) A step of dividing a circuit pattern by a calculation window of a predetermined size,
(2) a first calculation step of calculating a pattern area density in each calculation window divided by the step of dividing;
(3) a step of determining whether to perform in-layer mix and match (M & M) exposure as a result of the calculation by the first calculation step;
(4) A step of carving out a pattern to be exposed in the same layer M & M exposure when carrying out the same layer M & M exposure according to the step to be determined.
(5) a second calculation step of calculating, for each calculation window, a pattern area density of a pattern that is not exposed by the same layer M & M exposure that is cut by the step of cutting
(6) a first calculation step of calculating a target pattern area density for averaging based on a pattern area density of a pattern not exposed by the same layer M & M exposure calculated by the second calculation step;
(7) a second calculation step of calculating a prohibited area in which a dummy pattern should not be generated with respect to a pattern that is not exposed by the same layer M & M exposure that is cut by the cutting step;
(8) Generation / placement of dummy patterns is performed for each correction window on the basis of the target pattern area density for averaging calculated in the first calculation step and the prohibited area calculated in the second calculation step. Process,
(9) a third calculation step of calculating the pattern area density for each calculation window with respect to the pattern in which the dummy pattern is generated / placed by the step of generating / placement of the dummy pattern for each correction window;
(10) A step of determining whether or not the area density calculated by the third calculation step is within a predetermined range. A storage step of storing pattern information for placement on the mask in a storage device;
A virtual placement step of virtually placing a predetermined area on the mask;
A moving step of moving the predetermined region virtually arranged by the virtual arrangement step by a predetermined distance so as to overlap the previous region;
Based on the pattern information stored in the storage device by the storage step, a calculation step of calculating the area density in the predetermined region of the pattern drawn by the pattern information every time the predetermined region is moved by the moving step;
A dummy pattern information generation method comprising: a generation step of generating dummy pattern information for placement on the mask based on the area density calculated by the calculation step. A storage step of storing pattern information for placement on the mask in a storage device;
A virtual reduction step of virtually reducing the line width of the pattern by a predetermined size based on the pattern information stored in the storage device by the storage step;
As a result of the virtual reduction by the virtual reduction process, a calculation process for calculating the area density of the pattern that has disappeared,
A dummy pattern information generation comprising: a generation step of generating dummy pattern information to be arranged on the mask together with the pattern to be extinguished based on the area density calculated by the calculation step Method. A storage process for storing pattern information for placement on a mask in a storage device;
Virtual placement processing for virtually placing a predetermined area on the mask;
A movement process for moving the predetermined area virtually arranged by the virtual arrangement process by a predetermined distance so as to overlap the previous area;
Based on the pattern information stored in the storage device by the storage process, a calculation process for calculating the area density in the predetermined area of the pattern drawn by the pattern information every time the predetermined area is moved by the movement process;
A program for causing a computer to execute generation processing for generating dummy pattern information to be arranged on the mask based on the area density calculated by the calculation processing, or a computer-readable recording medium on which the program is recorded. A storage process for storing pattern information for placement on a mask in a storage device;
A virtual reduction process for virtually reducing the line width of the pattern by a predetermined size based on the pattern information stored in the storage device by the storage process;
As a result of virtual reduction by the virtual reduction process, a calculation process for calculating the area density of the pattern that has disappeared;
A program for causing a computer to execute generation processing for generating dummy pattern information to be arranged on the mask together with the pattern to be eliminated based on the area density calculated by the calculation processing or the program A recorded computer-readable recording medium.

Images