JP2004079699A - Mask pattern dividing method, mask pattern dividing program, and method of manufacturing exposure mask and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve processing that is quick and reliable by introducing a simple procedure even if a pattern as an object of division is very complicated in form in a complementary dividing process of an electron beam projection exposure mask. <P>SOLUTION: When an original pattern profile which is to be transferred by the use of an electron beam projection exposure mask is divided into a plurality of pattern profiles complementary to each other, following steps are provided, a step (S201) of subdividing the original pattern profiles into aggregates composed of rectangular patterns or triangular patterns as the apexes of the original pattern are made to serve as base points and steps (S202 to S207) of selectively compounding the subdivided rectangular or triangular patterns into the plurality of pattern profiles. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mask pattern division method and a mask pattern division program suitable for application to an electron beam projection exposure mask, an exposure mask thereof, and a semiconductor device manufacturing method using the exposure mask.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in a semiconductor device manufacturing process, patterning by conventional photolithography using ultraviolet rays has been becoming difficult due to advances in high integration and size reduction of semiconductor devices. For this reason, recently, a lithography technique using an X-ray, an electron beam, an ion beam, or the like has been proposed. Some of these new lithography techniques are different from the mask structure used in the conventional photolithography, for example, as in LEEPL (Low Energy E-beam Proximity Projection Lithography) for performing low-energy electron beam projection exposure. Some use an electron beam transmission type stencil mask provided with an opening having a shape corresponding to the pattern.
[0003]
Such an electron beam transmission type stencil mask has a pattern shape that cannot be held by itself (for example, a donut shape) or a difficult pattern shape (for example, a leaf, tongue, cantilever shape) due to its properties. Also, for example, a line-and-space pattern may not be able to be formed due to the collapse of the pattern depending on its length. That is, since an opening having a pattern shape is required, there are restrictions on the pattern shape that can be handled. For this reason, so-called complementary division (complementary division) is applied to the stencil mask. In the complementary division, a pattern shape that cannot be formed is complementarily divided, and a target pattern is transferred onto a wafer by transferring and combining a plurality of divided patterns.
[0004]
Conventionally, complementary division of a stencil mask is performed by geometric division according to a certain division rule. The certain division rule is that if the internal angle of the polygonal pattern is larger than a threshold value (for example, 180 °), the internal angle is divided. Such as dividing. In other words, the conventional complementary division is performed by geometrically dividing the pattern shape to be divided according to a certain division rule in order to eliminate a pattern shape that cannot be formed as a stencil mask.
[0005]
[Problems to be solved by the invention]
By the way, the complementary division of the stencil mask is performed only when the pattern shape to be divided is a rectangle 11 having a predetermined shape such as a contact layer for connecting the substrate and the wiring or the wiring as shown in FIG. For example, even if geometrical division is performed according to a certain division rule, there is no particular problem in processing. Further, when the pattern shape of the gate layer constituting the transistor is to be divided, the pattern shape is slightly more complicated than in the case of a rectangular shape having a fixed shape, but for example, the complexity is as small as the shape 12 shown in FIG. Then, it is possible to sufficiently cope by applying a certain division rule.
[0006]
However, if the pattern shape to be divided is very complicated, for example, an element isolation layer or a wiring layer, and can include any shape, the division process for the pattern shape becomes very complicated. Would. This is because, in the dividing process, a case dividing process for accommodating various shapes is required.
[0007]
In addition, in the complementary division of the stencil mask, the minute figure deteriorates the transfer performance. Therefore, it is necessary to avoid the existence of the minute figure in the pattern after division. However, if the pattern shape to be divided is simply divided according to a certain division rule, the divided pattern may include a minute figure. In such a case, it is necessary to redo the division at least in the vicinity of the minute figure, and as a result, the reliability of the division processing may be reduced and the processing load may be increased.
[0008]
In view of the above, the present invention introduces a simple procedure in the complementary division processing of an electron beam projection exposure mask such as a stencil mask in LEEPL, in which the pattern shape to be divided is very complicated. Also, it is an object of the present invention to provide a mask pattern dividing method and a mask pattern dividing program capable of realizing a quick and highly reliable process, an exposure mask obtained by these, and a method of manufacturing a semiconductor device using the exposure mask. With the goal.
[0009]
[Means for Solving the Problems]
The present invention is a mask pattern dividing method devised to achieve the above object. That is, a mask pattern division method for dividing an original pattern shape to be transferred using an electron beam projection exposure mask into a plurality of complementary pattern shapes, wherein each vertex of the original pattern shape is used as a base point. The method is characterized in that the original pattern shape is subdivided into a set of rectangular patterns or triangular patterns, and the subdivided rectangular or triangular patterns are selectively combined to obtain the plurality of pattern shapes.
[0010]
Further, the present invention is a mask pattern dividing program devised to achieve the above object. That is, a mask pattern division program for dividing an original pattern shape to be transferred using an electron beam projection exposure mask into a plurality of complementary pattern shapes. Means for subdividing the original pattern shape into a set of rectangular or triangular patterns, and means for selectively combining the subdivided rectangular or triangular patterns to obtain the plurality of pattern shapes. And
[0011]
Further, the present invention is an exposure mask devised to achieve the above object.
That is, this is an exposure mask in which a mask pattern obtained by complementarily dividing the original pattern shape is formed, and the mask pattern has a rectangular shape based on each vertex of the original pattern shape. It is obtained by subdividing into a set of patterns or triangular patterns and selectively combining the subdivided rectangular or triangular patterns.
[0012]
Further, the present invention is a method of manufacturing a semiconductor device devised to achieve the above object. That is, the original pattern shape to be transferred is divided into a plurality of complementary pattern shapes by using an electron beam projection exposure mask, and the plurality of pattern shapes are transferred, whereby the original pattern shape is formed on a wafer substrate. A method of manufacturing a semiconductor device for forming a corresponding pattern, wherein the original pattern shape is subdivided into a set of rectangular patterns or triangular patterns based on each vertex of the original pattern shape, and the subdivided rectangular pattern or triangle is formed. The pattern is selectively synthesized to obtain the plurality of pattern shapes.
[0013]
According to the mask pattern dividing method of the above procedure, the mask pattern dividing program of the above configuration, the exposure mask of the above configuration, and the method of manufacturing a semiconductor device of the above procedure, all of the original pattern shape is converted into a plurality of complementary pattern shapes. In the division, the original pattern shape is first subdivided into a set of rectangular patterns or triangular patterns, and the subdivided rectangular patterns or triangular patterns are selectively synthesized according to, for example, a predetermined reconstruction rule. That is, a plurality of pattern shapes are obtained by subdividing the original pattern shape to be divided, and then selectively synthesizing and reconstructing the original pattern shape. Therefore, even if the shape of the original pattern to be divided is complicated, if the subdivided rectangular pattern or the triangular pattern is synthesized so as not to generate a pattern shape that cannot be formed, case division processing and redo processing are performed. A plurality of pattern shapes after complementary division can be obtained without the necessity.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a mask pattern division method, a mask pattern division program, an exposure mask, and a method of manufacturing a semiconductor device according to the present invention will be described with reference to the drawings.
[0015]
The mask pattern dividing method described in the present embodiment is used in a manufacturing process of a semiconductor device corresponding to a fine line width such as a 100 nm or less generation. More specifically, for an electron beam projection exposure mask for forming a fine circuit pattern on a semiconductor wafer, an original pattern shape corresponding to a circuit pattern to be formed by the electron beam projection exposure mask is formed by a plurality of complementary patterns. Is used to divide the pattern into the following pattern shapes. Examples of the mask for electron beam projection exposure include an electron beam transmission type stencil mask in LEEPL.
[0016]
The mask pattern dividing method described in the present embodiment is realized by an apparatus having a function as a computer executing a mask pattern dividing program. That is, here, a case where the mask pattern dividing method is executed on a computer will be described as an example. In this case, various processes (coordinate point recognition, specific graphic extraction, and the like) described below may be performed using a well-known computational geometric technique, image processing technique, or the like. However, it is needless to say that it does not necessarily have to be executed on a computer.
[0017]
Here, the procedure of the above-described mask pattern dividing method will be described. FIG. 1 is a flowchart showing a procedure of a complementary division process to which the present invention is applied, and FIG. 2 is a flowchart showing an outline of a mask pattern division method performed using the complementary division process.
[0018]
First, the outline of the mask pattern dividing method will be described. As shown in FIG. 2, when dividing a mask pattern, the entire original pattern shape to be divided is input to a computer that executes a mask pattern dividing program (Step 101; hereinafter, steps are abbreviated as “S”). Then, with respect to the original pattern shape, the figures which are in contact with each other are connected (S102), and extracted as one pattern shape (S103). If the pattern shape taken out at this time is a pattern shape that can be formed as a stencil mask, the computer sets the one pattern shape to one of a plurality of divided pattern shapes (S104, S105). On the other hand, if the pattern shape cannot be formed, the computer performs complementary division processing on the extracted pattern shape (S104, S106). The mask pattern dividing method described in the present embodiment has a great feature in this complementary division processing.
[0019]
Subsequently, the complementary division processing will be described. As shown in FIG. 1, when performing the complementary division processing, first, the pattern shape to be processed (the pattern shape extracted in S103 in FIG. 2) is subdivided (S201). The subdivision is performed by simply dividing the pattern shape into each of the X-axis (horizontal) direction and the Y-axis (vertical) direction with each vertex of the pattern shape to be processed as a base point. In other words, a given pattern shape is subdivided by drawing a horizontal line and a vertical line from each vertex. Thereby, the pattern shape to be processed is subdivided into a set of rectangular patterns or triangular patterns.
[0020]
FIG. 3 is an explanatory diagram showing a specific example of the subdivided pattern. In the illustrated example, dividing lines are drawn in the X-axis direction and the Y-axis direction at all vertices of the pattern shape to be processed. Note that the dividing line from each vertex is not both the horizontal line and the vertical line, but may be only one of them. In any case, what kind of dividing line is to be drawn is set in advance.
[0021]
After the pattern shape is subdivided into a set of rectangular patterns or triangular patterns, the smallest figure pattern is extracted from the set (S202). As the smallest figure pattern, for example, it is conceivable to take out a figure pattern having the shortest side. However, it is also possible to take out the one with the shortest perimeter (periphery) or take out the one with the smallest area.
[0022]
Thereby, for example, in the example of the pattern shape shown in FIG. 3, the rectangular pattern “A” shown in the figure is extracted as the smallest figure pattern. The graphic pattern extracted at this time is hereinafter referred to as a “connection target graphic”.
[0023]
If there is no connection target graphic to be extracted at this stage (S203), the complementary division processing ends.
[0024]
After the connection target graphic is extracted, a connection candidate graphic is extracted (S204). The “connection candidate graphic” can be combined with the connection target graphic into one graphic pattern, and basically refers to a graphic pattern in contact with the connection target graphic.
However, since the stencil mask can be synthesized with the connection target graphic, the stencil mask that is difficult to be created by the synthesis is excluded.
[0025]
For example, in the example of the pattern shape shown in FIG. 3, for the connection target graphic A, the rectangular patterns “B”, “C”, “D” and “E” shown in the figure are extracted as connection candidate graphics. You.
[0026]
If no connection candidate graphic is extracted at this stage, that is, if there is no connection candidate graphic (S205), synthesis with the connection target graphic cannot be performed, and the connection target graphic has no problem in stencil mask creation. Since it is considered to be a graphic pattern, an output process is performed for the connection target graphic (S206). By this output processing, the connection target graphic is handled as one pattern shape that can be formed as a stencil mask, and is excluded from the target of the complementary division processing.
[0027]
After the connection candidate graphics are extracted, one of the extracted connection candidate graphics is selected from the extracted connection candidate graphics to be connected to the connection target graphic and synthesized (S207). This selection may be made according to the following rules.
[0028]
For example, from among several connection candidate figures, (1) a connection candidate figure having a longer side in contact with the connection target figure is preferentially selected. If there is an equivalent length, (2) after connecting and combining with the connection target figure, a connection candidate figure with a smaller number of complementary inconsistency points to be described later is preferentially selected. Further, when there is an equivalent number of reductions in complementary inconsistencies, (3) a connection candidate figure having a small increase in the number of vertices after being connected to the connection target figure and synthesized is preferentially selected. According to such a rule, any one connection candidate figure is selected. However, even if these conditions are satisfied, (4) those which make it difficult to create a stencil mask by connecting and combining with the connection target graphic (for example, those which constitute an L-shaped pattern) Is excluded from the selection.
[0029]
It should be noted that the rule for selecting a connection candidate graphic described here is merely an example, and the priority may be changed or another condition may be applied, for example. As another condition, for example, it is conceivable to preferentially select a connection candidate figure having an aspect ratio (aspect ratio) close to “1” after connecting and combining with a connection target figure.
[0030]
As described above, after selecting one of the connection candidate figures, the connection candidate figure is connected to the connection target figure and synthesized, and thereafter, these are treated as one figure. Specifically, for example, in the example of the pattern shape shown in FIG. 3, a connection candidate graphic B is selected from several connection candidate graphics B to E, and after these connection synthesis, the connection target graphic A and the connection candidate Figure B is handled as one rectangular pattern.
[0031]
Then, the connection synthesis of the connection target graphic and the selected connection candidate graphic returns to the step of extracting the smallest graphic pattern from the set of graphics including the synthesized graphic (S202) and returns to the above-described steps (S202 to S202). S207) is repeated until there is no more connection target graphic to be extracted, and more specifically, until the complementary contradictory point is resolved.
[0032]
This “complementary contradiction point” refers to a relationship between vertices that cannot be recognized in performing the complementary division processing. For example, in the case of complementary division into two masks, the presence of vertices where three or more figures are in contact is not allowed. Such unacceptable vertices are called complementary inconsistencies. Specifically, for example, in the example of the pattern shape shown in FIG. 3, vertices surrounded by a circle in the figure are complementary contradictory points.
[0033]
FIG. 4 is an explanatory diagram showing a specific example of a pattern reconstructed by the complementary division processing. After the connection synthesis of the connection target graphic A and the connection candidate graphic B for the pattern shape shown in FIG. 3, the above-described steps (S202 to S207 in FIG. 2) are repeated until the complementary inconsistency is resolved. ) To (g), the subdivided rectangular patterns are sequentially and selectively synthesized. Thereby, a plurality of pattern shapes as shown in FIG. 4G can be obtained from the pattern shape shown in FIG.
[0034]
Each of the plurality of pattern shapes obtained in this way can be formed as a stencil mask. That is, there is no small figure or L-shaped pattern that is not suitable for forming a stencil mask. Therefore, after the complementary division processing is performed, the pattern shape obtained in this manner is set as one of a plurality of pattern shapes obtained by dividing the original pattern shape to be divided (see S104 and S105 in FIG. 2). ). As a result, the original pattern shape is divided into a plurality of complementary pattern shapes. Each of the plurality of pattern shapes is individually formed on the stencil mask as a mask pattern on the stencil mask.
[0035]
Here, a stencil mask obtained through the above-described mask pattern division method (complementary division processing) will be briefly described. FIG. 5 is a perspective view showing an outline of the stencil mask. The stencil mask 1 used in the LEEPL is provided at a position directly above a wafer as an object to be exposed and performs proximity exposure, thereby transferring a fine pattern onto the wafer. For this purpose, the stencil mask 1 includes a strut 2 having a beam structure for reinforcing the mask, and a drawing area other than the strut 2, specifically, a membrane region having a thickness of about 5 μm or less. 3, an electron beam transmission groove corresponding to the fine pattern to be transferred (hereinafter, the pattern of this groove is referred to as a “mask pattern”) is formed. When the electron beam transmitted through the groove portion of the membrane region 3 reaches the resist previously coated on the wafer, for example, if it is a positive resist, the drawn portion of the electron beam dissolves in alkali. Thus, a fine pattern corresponding to the mask pattern is formed.
[0036]
Meanwhile, the mask pattern formed on the stencil mask 1 is obtained through the above-described mask pattern dividing method. That is, on the stencil mask 1, the mask patterns corresponding to the pattern shape after the original pattern shape is complementarily divided are arranged side by side. Therefore, when the stencil mask 1 is used in a lithography step in a semiconductor device manufacturing process, exposure is performed a plurality of times while moving the relative position between the stencil mask 1 and a wafer as an object to be exposed. Is transferred to the original pattern shape.
[0037]
As described above, in the mask pattern dividing method described in the present embodiment, the mask pattern dividing program for realizing the same, the resulting stencil mask and the method of manufacturing a semiconductor device using the stencil mask, the original pattern shape is complemented. In order to divide the original pattern shape into a plurality of typical pattern shapes, first, the original pattern shape is subdivided into a set of rectangular patterns or triangular patterns, and the subdivided rectangular patterns or triangular patterns are selected according to a predetermined fixed reconstruction rule. It is designed to be synthesized. That is, a plurality of pattern shapes are obtained by subdividing the original pattern shape to be divided, and then selectively synthesizing and reconstructing the original pattern shape. Therefore, even if the shape of the original pattern to be divided is complicated, if the subdivided rectangular pattern or the triangular pattern is synthesized so as not to generate a pattern shape that cannot be formed, case division processing and redo processing are performed. Thus, a plurality of pattern shapes after complementary division can be obtained without the necessity.
[0038]
That is, the complementary division processing described in the present embodiment is not a divisional method that is dangerous from the viewpoint of software reliability, but once subdivides the original pattern shape and does not cause a problem in stencil mask creation. Since such a pattern is formed by building simple patterns, a simple procedure can be introduced for complementary division processing for a stencil mask. Therefore, even when the pattern shape to be divided is very complicated, it is possible to realize a rapid and highly reliable division process, and the lithography process using a stencil mask has high reliability and high-speed processing. You can expect it.
[0039]
In this embodiment, the case where the present invention is applied to a stencil mask in LEEPL has been described as an example. However, the present invention is not limited to this, and a mask for a mask used for stencil-like projection exposure is used. If it is a pattern division process, it can be applied in exactly the same manner even if it is used in other lithography techniques (for example, those using X-rays, electron beams, ion beams, etc.).
[0040]
【The invention's effect】
As described above, in the present invention, in the complementary division processing of the mask for electron beam projection exposure, the original pattern shape to be divided is once subdivided and then selectively synthesized and reconstructed. A plurality of pattern shapes can be obtained from the original pattern shape by a simple procedure, and even if the pattern shape to be divided is extremely complicated, a quick and highly reliable process can be realized.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating an example of a procedure of a complementary division process to which the present invention is applied.
FIG. 2 is a flowchart illustrating an outline of a mask pattern division method performed using complementary division processing to which the present invention is applied.
FIG. 3 is an explanatory diagram showing a specific example of a pattern finely divided by a complementary division process to which the present invention is applied.
FIG. 4 is an explanatory diagram showing a specific example of a pattern reconstructed by complementary division processing to which the present invention has been applied.
FIG. 5 is a perspective view showing an outline of a stencil mask.
FIG. 6 is an explanatory diagram showing an example of a pattern shape of a contact layer for connecting a substrate and a wiring or a wiring.
FIG. 7 is an explanatory diagram illustrating an example of a pattern shape of a gate layer included in a transistor.
[Explanation of symbols]
1. Stencil mask, 2. Struts, 3. Membrane area

Claims (4)

A mask pattern division method for dividing an original pattern shape to be transferred into a plurality of complementary pattern shapes using an electron beam projection exposure mask,
Subdividing the original pattern shape into a set of rectangular or triangular patterns based on each vertex of the original pattern shape,
A method of dividing a mask pattern, wherein the plurality of pattern shapes are obtained by selectively combining subdivided rectangular or triangular patterns. A mask pattern division program for dividing an original pattern shape to be transferred into a plurality of complementary pattern shapes using an electron beam projection exposure mask,
Computer
Means for subdividing the original pattern shape into a set of rectangular or triangular patterns with each vertex of the original pattern shape as a base point,
A mask pattern division program that functions as means for selectively combining subdivided rectangular or triangular patterns to obtain the plurality of pattern shapes. An exposure mask in which a mask pattern obtained by complementarily dividing the original pattern shape is formed,
The mask pattern is obtained by subdividing the original pattern shape into a set of rectangular patterns or triangular patterns based on each vertex of the original pattern shape, and selectively combining the subdivided rectangular patterns or triangular patterns. An exposure mask, wherein Using an electron beam projection exposure mask, the original pattern shape to be transferred is divided into a plurality of complementary pattern shapes, and the plurality of pattern shapes are transferred, whereby the original pattern shape on the wafer substrate is corresponded. A method for manufacturing a semiconductor device for forming a pattern,
Subdividing the original pattern shape into a set of rectangular or triangular patterns based on each vertex of the original pattern shape,
A method of manufacturing a semiconductor device, characterized by selectively combining subdivided rectangular or triangular patterns to obtain the plurality of pattern shapes.

Images