JP2690911B2 - Electron beam drawing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing pattern generation technique and an electron beam drawing technique using the same, and particularly to an integrated circuit for a semiconductor wafer, which is implemented in a semiconductor device manufacturing process. The present invention relates to a technique effectively applied to transfer of a pattern or the like. [Prior Art] For example, as a method of irradiating an electron beam resist applied to a semiconductor wafer with an electron beam and exposing it to transfer an integrated circuit pattern or the like, the shape of the photoelectron surface of the electron beam is variable and variable. Shaped beam method is known. In this variable shaped beam system, since the drawing operation is performed in the unit of the area of the photoelectron surface of the electron beam that can be generated in the electron beam shaper (hereinafter referred to as shot),
In order to increase the number of semiconductor wafers that are drawn per unit time, the area of the photoelectron surface (shot
It is necessary to increase the size (referred to as size) to reduce the number of shots. On the other hand, when the shot size of the electron beam is increased, the contouring of the photoelectron surface becomes blurred due to proximity effect and the like, which lowers the drawing accuracy. There is a contradictory relationship, and as measures against this, for example, the techniques disclosed in Japanese Patent Laid-Open Nos. 58-82615 and 59-199553 have been proposed. That is, for example, in the case of exposing a positive type resist, the former divides a drawing area surrounding a target figure into a plurality of areas, and further divides each divided area into a contour portion and an inside portion. In order to secure the drawing accuracy by reducing the shot size, and to increase the shot size as much as possible internally to reduce the number of shots, it is attempted to achieve both the drawing accuracy and the drawing speed. In the latter case, the upper limit of the shot size is set so that an error such as contour blurring due to the proximity effect does not occur. [Problems to be Solved by the Invention] However, in the former conventional technique, the number of shots is increased because a contour portion having a large number of shots is formed even in a portion that does not contact a target figure and does not require drawing accuracy. There is a problem in that the degree of reduction is relatively small, and it is not possible to expect an improvement in drawing speed while maintaining drawing accuracy. Further, when the upper limit is set to the shot size as in the latter case, there is a problem that the drawing speed can be improved but the drawing speed cannot be improved. An object of the present invention is to provide a drawing figure generation technology capable of increasing the number of objects to be drawn per unit time without lowering drawing accuracy, and an electron beam drawing technology using the same. Especially. The above and other objects and novel features of the present invention are as follows.
It will be apparent from the description of this specification and the accompanying drawings. [Means for Solving Problems] The above-mentioned objects are: a step of preparing a substrate coated with a positive resist, a step of expanding a plurality of adjacent original figures to obtain first figure data, Obtaining the second figure data surrounding the original figure by taking the exclusive OR of the one figure data and the original figure; and the third figure by taking the logical NOT of the first figure data. A step of obtaining data, and a step of obtaining a drawing figure by combining the third figure data and the second figure data,
A step of drawing a figure on the substrate with an electron beam having a shot size that does not affect the proximity effect between the plurality of original figures that are close to each other based on the second figure data; and the shot size based on the third figure. A step of drawing a graphic on the substrate with an electron beam having a larger shot size, and a step of preparing a substrate coated with a negative type resist; Of degrading the original figure to obtain the first figure data, and obtaining the second figure data surrounding the original figure by taking the exclusive OR of the first figure data and the original figure. And a step of obtaining third graphic data by taking a logical product of the original graphic and the first graphic data, and synthesizing the third graphic data and the second graphic data. A step of obtaining a drawing figure further, a step of drawing a figure on the substrate with an electron beam having a shot size that does not affect the proximity effect between the plurality of adjacent original figures based on the second figure data, Based on the graphic data, the step of drawing a graphic on the substrate with an electron beam having a shot size larger than the shot size. [Operation] According to the above-described means, in drawing with the second figure data in contact with the original figure, the shot size of the electron beam is reduced to prevent the occurrence of an error due to the proximity effect or the like with high precision. The third that does the action and does not touch the original figure
In drawing with the figure data, the shot size of the electron beam is increased as much as possible to reduce the number of shots, so that the dimensional accuracy of important parts such as the outline of the original figure is not impaired The number of shots can be reduced, and the number of objects to be drawn per unit time can be increased without lowering the drawing accuracy. [Embodiment] FIG. 1 is a block diagram showing an essential part of an electron beam drawing apparatus for carrying out exposure with a drawing figure according to an embodiment of the present invention, and FIG. 2 is a drawing figure generating method of the present invention. Drawing figures obtained by the method, and FIGS. 3 to 7 are explanatory views for explaining the steps of the drawing figure generating method. An object 2 made of, for example, a semiconductor wafer having a surface coated with an electron beam resist or the like is detachably mounted on an XY table 1 which is movable in a horizontal plane. An electron gun 3 is provided vertically downward above the XY table 1 so that an electron beam E is emitted to an object 2 placed on the XY table 1. There is. An electron beam E emitted from the electron gun 3 to the object 2 to be drawn.
By controlling the passage path of the electron beam E to a plurality of apertures (not shown) in which a transmission window of the electron beam E is formed in a predetermined figure, the photoelectron surface of the electron beam E can be made to have a desired shape and size. And an electron lens 5 for controlling the focal position of the electron beam E with respect to the object 2 to be drawn, and a deflector 6 for controlling the arrival position of the electron beam E with respect to the object 2 to be drawn. An optical system is provided. Further, the XY table 1, the electron gun 3, the electron optical system provided in the path of the electron beam E, etc. are housed in a vacuum container (not shown) whose internal vacuum degree can be controlled to a desired value. A control computer 7 is provided outside the vacuum container (not shown), and the XY table 1 is controlled by the control computer via the XY table drive unit 1a. Further, the control computer 7 is connected to an original figure information storage section 8 for storing information on an original figure to be transferred to the drawing object 2, and the original figure stored in this original figure information storage section 8 is connected. Information is transferred to the buffer memory 9 via the control computer 7 at any time. In this case, in the buffer memory 9, a drawing figure calculation unit 10 for calculating a drawing figure by a predetermined algorithm described later based on the information of the original figure transferred to the buffer memory 9.
Is connected. Further, the drawing figure calculation unit 10 controls the shaper 4 via the shaper controller 11a based on the information of the drawing figure, and thereby controls the shape of the photoelectron surface of the electron beam E. And the electronic lens controller 12a and the deflection controller 1
By controlling the electron lens 5 and the deflector 6 via 2b, the irradiation position signal generator 12 for controlling the irradiation position of the electron beam E on the object to be drawn 2 is connected. Hereinafter, the operation of the present embodiment will be described. In the present embodiment, a case where a positive type electron beam sensitive resist is applied to a semiconductor wafer or the like as the object to be drawn 2 will be described. First, the XY table 1 is appropriately moved to position the center of a predetermined element formation region 2a of the object 2 to be drawn such as a semiconductor wafer on the axis of the electron gun 3. At the same time, in the buffer memory 9, via the control computer 7, information of the target original figure P ₁ , original figure P ₂ , and original figure P ₃ to be transferred to the element forming area 2a as shown in FIG. Transferred. Here, in the case of transferring a plurality of original figures P ₁ to P ₃ to the device formation region 12, since the electron beam sensitive resist is a positive, original figure P ₁ to P in the interior of the element formation region 2a It is necessary to expose the peripheral portion of ₃ with the electron beam E. Therefore, the drawing information given to the buffer memory 9 via the control computer 7 is shown in FIG. 5 by expanding the plurality of original figures P _{1 to} P ₃ shown in FIG. 4 by the figure generating computer. The first step of obtaining the plurality of first graphic data P _1a and the first graphic data P _{2a shown} in FIG. 1 and the plurality of first graphic data P _1a , P _2a and the original graphics P _{1 to} P ₃ A second graphic data C ₁ and a second graphic data C ₂ that surround and are in contact with the original graphics P _{1 to} P ₃ are obtained by calculating the exclusive OR, as shown in FIG. The third step of obtaining the third figure data S ₁ shown in FIG. 7 by the logical negation of the plurality of original figures P _{1 to} P ₃ , and the third figure data S ₁ . After the fourth step of combining the second graphic data C ₁ and C ₂ with each other, the drawing graphic X is calculated as shown in FIG. In addition, the third figure forming the drawing figure X obtained in this way
The graphic data S ₁ and the second graphic data C ₁ and C ₂ are divided into a plurality of shots E _{a1 to} E _an and a plurality of shots E _{b1 to} E _bn , respectively, as shown in FIG. By repeating the drawing operation with the electron beam E of each shot,
The outer peripheral portions of the original figures P _{1 to} P ₃ are exposed by the electron beam E. Here, the width of the original figure P ₁ to P second figure data C ₁ in contact surrounding the _3, C ₂ is a constant regardless of the original figure P ₁ to P _3, further Second figure data
The individual areas of the shots E _{b1 to} E _bn forming C ₁ and C ₂ are equal to or smaller than the maximum shot size A _max without the influence of the proximity effect shown by the broken line in the upper left side of FIG. Is controlled so that the exposure accuracy in the contour portions of the original figures P _{1 to} P ₃ is maintained. On the other hand, a plurality of shots forming the third figure data S ₁
Since the sizes of E _{a1 to} E _an are not in contact with the original figures P _{1 to} P ₃ , the drawing operation is performed with the shot size as large as possible without concern about the blurring of the contour due to the proximity effect. The number of shots can be reduced. FIG. 8 is a diagram showing the degree of contribution of the increase in the shot size of the electron beam E to the reduction in the number of shots in the case of drawing the signal line layer and in the case of the power supply layer in the semiconductor integrated circuit. Even in the case, it is known that increasing the shot size is extremely effective in reducing the number of shots. As a result, as shown in FIG. 9, for example, the electron beam having the maximum shot size A _max or less, which is not affected by the proximity effect, is simply surrounded by the surroundings of the original figures P _{1 to} P _3. Compared to the case of drawing uniformly with E,
The number of shots is greatly reduced. As a result, the time required for the drawing process of each of the drawing objects 2 is shortened, and the number of drawing objects 2 drawn per unit time is increased without impairing the drawing accuracy of the original figures P _{1 to} P _3. Can be made. Note that this is the same even when the electron beam resist applied to the semiconductor wafer as the drawing object 2 is a negative type. That is, in this case, in the first step, a plurality of first figure data are obtained by degenerating the plurality of original figures P _{1 to} P ₃ shown in FIG.
In the third step, the third figure data is calculated by taking the logical product of the original figures P _{1 to} P _{3 and} this first figure data, and the third figure data and the second figure data are calculated. by combining the data, the second graphic data in contact with the original figure P ₁ to P ₃ of the inner side from the contour in a predetermined width of the raw figure P ₁ to P _3, further therein, the original figure P It is possible to obtain a drawing figure composed of the third figure data that does not directly contact the contours _{1 to} P ₃ . As described above, according to this embodiment, the following effects can be obtained. (1). A first step of obtaining a plurality of first figure data P _1a and first figure data P _2a by expanding a plurality of original figures P _{1 to} P ₃ , and a plurality of the first figure data P _1a , P
By calculating the exclusive OR of the _2a and the original figure P ₁ to P _3, to obtain raw figures P ₁ to P second figure data C ₁ in contact surrounding the _3, the second graphic data C ₂ The third figure data is obtained by the second step and the logical negation of the plurality of original figures P _{1 to} P _3.
A third step of obtaining the S _1, and graphic data S ₁ of the third, since the operation of the drawing figures X through the fourth step of combining the graphic data C _1, C ₂ of the second , When drawing the second figure data C ₁ and C ₂ in contact with the contours of the original figures P _{1 to} P _3, the shot size is made relatively small so as not to be affected by the proximity effect of the electron beam E. Drawing operation is performed and the original figure P ₁ ~
The not contact directly to the contour of the P ₃ 3 of when the drawing of the graphic data, drawing operation with less number of shots by increasing the shot size as possible without worrying about the deterioration of drawing accuracy due proximity effect Can be performed, and the time required for drawing can be shortened without impairing the drawing accuracy of the contours of the original figures P _{1 to} P ₃ , and the number of objects 2 to be drawn processed per unit time can be reduced. Can be increased. (2). As a result of (1) above, the productivity in the wafer processing step in the manufacture of semiconductor devices is improved. Although the invention made by the inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention. Nor. In the above description, the case where the invention made by the present inventor is mainly applied to the electron beam exposure technique of the semiconductor wafer which is the field of application which is the background has been described, but the present invention is not limited to this, It can be widely applied to general drawing techniques that require accurate and rapid drawing of figures. [Effects of the Invention] The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. That is, the first step of obtaining a first figure data by expanding or contracting an original figure in a method of generating a figure in electron beam drawing of a variable shaped beam method, and
Second step of obtaining the second figure data by taking the exclusive OR of the figure data and the original figure, and the logical negation of the first figure data, or the original figure and the first figure A third step of obtaining the third figure data by taking the logical product of the first figure data and a fourth step of obtaining the drawing figure by synthesizing the third figure data and the second figure data. When the second graphic data in contact with the original graphic is used for drawing, the shot size of the electron beam is reduced to perform a high-precision drawing operation in which an error due to the proximity effect is prevented. , When drawing with the third graphic data that does not touch the original graphic,
By increasing the shot size of the electron beam as much as possible to reduce the number of shots, it is possible to reduce the number of shots in the entire drawing work without impairing the dimensional accuracy of important parts such as the outline of the original figure. Therefore, the number of objects to be drawn per unit time can be increased without lowering the drawing accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an essential part of an electron beam drawing apparatus for carrying out exposure using drawing figures according to an embodiment of the present invention, and FIG. 2 is a drawing figure generation of the present invention. Drawing figure obtained by the method, FIG. 3 is a figure showing a drawing figure, FIG. 4 is a figure showing an original figure, FIG. 5 is a figure showing first figure data, and FIG. 6 is second figure data. FIG. 7 is a diagram showing the third graphic data, FIG. 8 is a diagram showing the relationship between the shot size of the electron beam and the total number of shots, and FIG. 9 is an example of a conventional drawing apparatus. FIG. 1 ... XY table, 1a ... XY table drive unit,
2 ... Object to be drawn, 2a ... Element forming region, 3 ... Electron gun,
4 ... Shaper, 5 ... Electron lens, 6 ... Deflector, 7 ...
... control computer, 8 ... original figure information storage section, 9 ... buffer memory, 10 ... drawing figure calculation section, 11 ... shaping signal generation section, 11a ... shaper control section, 12 ... irradiation position signal generation Section, 12a ... Electron lens control section, 12b ... Deflector control section,
E: Electron beam, A _max: Maximum shot size without loss of accuracy due to proximity effect, P _{1 to} P ₃ ... Original figure, P _1a , P _2a
…… First graphic data, C ₁ , C ₂ …… Second graphic data, S
₁ ... Third figure data, E _{a1 to} E _an ... Shots configured by dividing the third figure data, E _{b1 to} E _bn ... Shots configured by dividing the second figure data , X …… Drawing figure.

Claims (1)

(57) [Claims] A step of preparing a substrate coated with a positive type resist, a step of expanding a plurality of adjacent original figures to obtain first figure data, and an exclusive OR of the first figure data and the original figure To obtain second graphic data that surrounds the original graphic data, and to obtain a logical NOT of the first graphic data to obtain a third graphic data.
Of the figure data, a step of obtaining a drawing figure by synthesizing the third figure data and the second figure data, and the plurality of original figures that are adjacent to each other based on the second figure data. Drawing a graphic on the substrate with an electron beam having a shot size that does not affect the proximity effect, and drawing a graphic on the substrate with an electron beam having a shot size larger than the shot size based on the third graphic data. An electron beam drawing method, comprising: 2. A step of preparing a substrate coated with a negative resist, a step of degenerating a plurality of adjacent original figures to obtain first figure data, an exclusive OR of the first figure data and the original figure Obtaining the second figure data surrounding the original figure, and obtaining the third figure data by taking the logical product of the original figure and the first figure data; A step of obtaining a drawing figure by synthesizing the figure data and the second figure data; and a shot-size electron which is not affected by a proximity effect between the plurality of adjacent original figures based on the second figure data A step of drawing a graphic on the substrate with a beam, and a step of drawing a graphic on the substrate with an electron beam having a shot size larger than the shot size based on the third graphic data. Electron beam lithography method according to symptoms.