JP3462074B2 - Drawing data creation method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a technique for creating drawing data such as electron beam drawing from circuit design pattern data of a semiconductor integrated circuit or the like. The present invention relates to a drawing data creation method effective for creating data. 2. Description of the Related Art As a semiconductor integrated circuit becomes larger in scale and a device becomes finer, a technique of drawing a pattern on a wafer or a mask using a drawing apparatus has been adopted. L created by logic design, circuit design and layout design
In order to draw a predetermined pattern on a wafer or a mask using a drawing apparatus by using the SI design pattern data, the design pattern data must be converted into drawing data for the drawing apparatus. In the process of converting the design pattern data into the drawing data, it is necessary to convert the pattern data having a multi-layer cell hierarchical structure into a one-layer cell hierarchical structure for drawing data. When forming one layer, the overlap is removed so that the drawing accuracy is not degraded by the multiple exposure due to the overlap of the figures, the dimension is corrected by enlarging / reducing the design pattern data, and the pattern corrected in this manner is used by the drawing apparatus. Processing such as division into a drawable figure is performed. However, as the size and scale of LSIs increase, the amount of data processed by the drawing apparatus is steadily increasing. In recent years, as a method of converting into drawing data, a technique which enables compression of drawing data has been proposed. As one of the conventional examples, there is JP-A-5-29202. In this method, as shown in FIG. 1, a pattern which is arranged a plurality of times in design pattern data is divided into sub-deflection scanning areas in electron beam writing to obtain arrangement information of a basic figure and compress the data amount. That is what we are trying to do. However, in the above-described conventional example, data is compressed using the basic figure after dividing into the sub-deflection scanning area. The basic figure is a figure of the size of the sub-deflection scanning area. There is a problem that compression processing is not performed on patterns other than the above, and only a specific pattern called a basic figure is compressed. An object of the present invention is to provide a drawing data creation method for reducing the amount of drawing data supplied to a drawing apparatus. The present invention is used in a beam exposure method for forming a pattern on a sample using a multi-stage deflection drawing apparatus having a main deflection device and at least one or more sub-deflection devices. It is assumed that After the sub-deflection data used in the above-described beam exposure method is created, a plurality of adjacent patterns in the same minimum sub-deflection scanning area including the drawing pattern are merged, and a process of re-expressing with a new drawing pattern is performed. First, the sum of the areas of all the adjacent patterns in the minimum sub-deflection scanning area is obtained, and when the size becomes the same as the size of the minimum sub-deflection scanning area, the entire area of the minimum sub-deflection scanning area is covered. The pattern of the minimum sub-deflection scanning area is expressed using a data structure expressing According to the present invention, a plurality of adjacent drawing patterns within the same minimum sub-deflection scanning area are merged, and the process of re-expressing them with a new drawing pattern is performed after the sub-deflection data is created. Compressed drawing data can be created. FIG. 2 is a schematic diagram showing a main-sub two-stage deflection type electron beam writing apparatus used in an embodiment of the present invention. In the figure, reference numeral 10 denotes a sample chamber, in which a stage 12 on which a sample 11 such as a semiconductor wafer or a mask is mounted is accommodated. The stage 12 is driven by a stage drive circuit 13 in the X direction (left-right direction on the page) and the Y direction (front-back direction on the page). The moving position of the stage 12 is measured by a position circuit 14 using a laser length meter or the like. An electron beam optical system 20 is arranged on the document 11. The optical system 20 includes an electron gun 21, various lenses 22 to 26, a deflector 31 for blanking, a deflector 32 for varying the beam size, a main deflector 33 for beam scanning, a sub deflector 34 for beam scanning, and a beam shaping aperture 3.
5, 36 and the like. And the main deflector 33
, A sub-deflection scanning area (hereinafter, referred to as a sub-field), a sub-deflector 34 positions a figure drawing unit in the sub-field, and a beam size changing deflector 32 and a beam shaping aperture 35. , 36, and draws a frame area obtained by dividing the LSI chip into strips according to the main deflection beam deflection width while continuously moving the stage 12 in one direction. Further, the stage 12 is step-moved in a direction orthogonal to the continuous movement direction, and the above processing is repeated to sequentially draw each frame area. On the other hand, a storage medium 41 such as a magnetic disk is connected to the control computer 40, and the magnetic disk 41 stores LSI drawing data. The drawing data read from the magnetic disk 41 is stored in a pattern memory (data buffer unit) 42 for each frame area.
Is stored temporarily. Pattern data for each frame area stored in the data buffer unit 42, that is, frame information including a drawing position and graphic data, is analyzed by a pattern data decoder 43 and a drawing data decoder 44, which are data analysis units, and blanking is performed. Circuit 45, beam shaper driver 46, main deflector driver 4
7 and the sub-deflector driver 48. That is, in the pattern data decoder 43,
The above data is input, and if necessary, the graphic data included in the frame area is subjected to inversion processing to generate inverted pattern data. Then, the graphic data defined as the frame data is formed by the shaping apertures 35 and 36.
Are divided into a group of unit drawing figures that can be formed by the combination of the above, blanking data is created based on this data, and sent to the blanking circuit 45. Further, desired beam size data is created, and the beam size data is sent to the beam shaper driver 46. Next, a predetermined deflection signal is sent from the beam shaper driver 46 to the beam size changing deflector 32 of the optical system 20, whereby the size of the electron beam is controlled. The drawing data decoder 44 creates sub-field positioning data based on the frame data, and sends this data to the main deflector driver 47. Then, a predetermined signal is sent from the main deflector driver 47 to the main deflector 33 of the optical system, whereby the electron beam is deflected and scanned to a designated subfield position. Further, the drawing data decoder 44 generates a sub deflector scanning control signal, and this signal is sent to the sub deflector driver 48. Then, the sub deflector driver 48
Sends a predetermined sub-deflection signal to the sub-deflector 34, whereby drawing is performed for each sub-field. An LSI using the apparatus configured as described above
FIG. 3 shows a data creation process for performing a pattern drawing process. An LSI pattern is created by a CAD system, and the LSI design pattern data output from the system is converted into drawing data by a data conversion computer.
The drawing data is read out, and the drawing processing by the electron beam is performed. FIG. 4 shows that the LSI design pattern data is converted into data acceptable by the electron beam lithography apparatus through data conversion processing through pattern duplication elimination, trapezoidal division, and the like, and can be further exposed by the lithography apparatus by the pattern data decoder 43 of the lithography apparatus. It shows how the image is divided into various rectangles or triangles. However, here, it is divided only into a rectangular pattern. Next, a drawing data generating method according to an embodiment of the present invention which is optimal for the above-described drawing apparatus will be described in detail.
FIG. 5 is a flowchart showing the flow of a process for converting data from LSI design pattern data acceptable to the drawing apparatus according to the present embodiment. The contents of the processing will be described according to this flowchart. First, design pattern data having a multi-layer cell hierarchical structure is input, and hierarchical optimization processing including pre-processing (such as donut processing) for removing cell duplication and resizing is performed. The hierarchical structure of the design data is changed so that a suitable hierarchical graphic operation process can be performed. Next, a hierarchical graphic operation process is performed on the design pattern data subjected to the hierarchical optimization. The graphic operation includes, for example, a black-and-white inversion process, a mirror inversion process, a resize process, and the like. If only a trapezoid is allowed as a pattern that can be input to the drawing apparatus, trapezoid division of the pattern is also performed at this stage. Next, subfield division is performed on cells larger than the subfield size. After the subfield division, a plurality of adjacent patterns in the subfield, which is a characteristic part of the embodiment of the present invention, are merged, it is determined whether or not the pattern can be represented by a new pattern. Do. Finally, the cells are sorted into the respective frames, and the creation of the drawing data is completed. The details of the compression processing according to the above-described embodiment of the present invention will be described below. FIGS. 6A and 7
(A) is a figure group after subfield division. FIG.
7 (a) and all the figures defined in FIG. 7 (a) are in contact with adjacent figures. According to each step of the flow shown in FIG. 8, the figures in the subfield are shown in FIGS. 6 (a), 6 (b) and 7
(A) is represented as shown in FIG. 7 (b). The description will be given in order below. Step 1: One subfield (sf) after subfield division is extracted. Step 2: The figure area of all figures in the extracted subfield is obtained. Step 3: The sum (SA) of the areas of all figures obtained in the above steps and the subfield area (SZ = sfx × sf)
y) is compared (1) If SA = SZ, go to step 4. (2) If SA ≠ SZ, go to Step 5 Step 4: Replace with a figure (sf figure) having the same size as the subfield area (see FIG. 6B). Alternatively, the data is replaced with a data structure (special drawing pattern) indicating that the entire surface of the minimum sub-deflection area is covered. Go to step 10. Step 5: Extract all combinations of adjacent figures. Step 6: When adjacent graphics are merged, it is determined whether or not they can be represented by a drawing pattern. Step 7: Fuse adjacent figures. Step 8: Have the judgments of step 6 been made for all combinations of adjacent figures? (1) If all combinations have been determined, go to step 9. (2) If all combinations have not been determined, go to step 6. Step 9: Has fusion determination been performed for all figures in the subfield? (1) If all figures have been determined, step 1
0 (2) If all figures are not determined, go to Step 5 Step 10: Change the figure configuration in the subfield,
Optimization (see FIG. 7B). Step 11: end when all subfields have been extracted. If all subfields have not been extracted, step 1
What. In this embodiment, steps 2, 3, and 4 are performed in order to quickly detect the case where the entire subfield is covered with a pattern.
Has been introduced. When a part or the whole of the subfield is covered with a stripe pattern, a pattern connected in a stripe pattern is searched before the step 5 in order to fuse the subfield at a high speed. May be performed. In the conventional processing, the basic graphic is classified into sub-deflection scanning areas (sub-fields), and then the arrangement information is obtained and compressed for the basic graphic. In this case, only the basic graphic in sub-field units is generated. No compression effect is applied to patterns other than the basic graphic. However, in this embodiment, a figure which cannot be compressed by the related art can be compressed by merging an adjacent figure with a figure in a subfield and expressing the figure with a new figure. Although the present invention has been described based on the embodiments, the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example,
The configuration of the electron beam writing apparatus is not limited to that shown in FIG. 2 and can be changed as appropriate. Further, in the present embodiment, the description has been given by taking the example of the electron beam drawing apparatus of the main-sub two-stage system, but the multi-stage deflection system may be used, and the invention can be applied to a charged beam other than the electron beam. According to the present invention described in detail above, a process of fusing a plurality of adjacent patterns within the same minimum sub-deflection scanning area and re-expressing them with a new pattern is performed in writing data creation. By performing this after the deflection data is created, it is possible to create drawing data with a reduced data amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing processing in a conventional example. FIG. 2 is an electron beam drawing used in a method of an embodiment of the present invention. FIG. 4 shows a drawing data generation process. FIG. 5 is a flowchart showing a main processing flow in data conversion. FIG. 6 is an explanatory diagram showing a configuration of a figure in a subfield. FIG. FIG. 8 is an explanatory diagram showing a configuration of a graphic in a field.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-283423 (JP, A) JP-A-7-321004 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027

Claims (1)

(57) Claims 1. Drawing data used in a beam exposure method for forming a pattern on a sample using a multi-stage deflection drawing apparatus having a main deflection apparatus and at least one sub-deflection apparatus. Work
A forming method, after creating sub-deflection data, combines the plurality of patterns adjacent the same minimum sub deflection scanning region including a drawing pattern, prior to performing the process of re-expressed in a new drawing pattern, before
Surfaces of all the adjacent patterns in the minimum sub-deflection scanning area
The sum of the products is obtained and is equal to the size of the minimum sub-deflection scanning area.
Is reached, the entire surface of the minimum sub-deflection area is covered.
The minimum sub-deflection scanning area using a data structure
A drawing data creation method characterized by expressing a pattern of a region .