JP2000047361A - Method for correcting reticle drawing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to shorten the time required for layout work at the time of reticle formation and to simplify the work by automatically adding or deleting adequate modification patterns to angle parts, thereby forming the patterns of the adequate reticle. SOLUTION: The patterns of the reticle are divided to microdots of a square shape or the rectangular shape conforming thereto at a length of 1/5000 based on design rule in length on one side. The dots to be corrected according to the predetermined arrangement state of the dots on the circumference are selected and the modification patterns of the sizes and shapes predetermined around these dots are added or deleted, by which the correction is made so as to lessen the influence by a light proximity effect. For example, dots D, L and LL exist as the dots adjacent to a dot a1 in question. Here, the modification patterns in the overhanging shape of the rectangular shape of the size up to the dot a1000 of the 1000th order are added along the side of the dot a1 in the case of the size of the dot at 1/5000 of the design rule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the formation of a photomask in a manufacturing process of a semiconductor device, and more particularly to a method for correcting a reticle drawing by OPC (Optical Proximity Correction).

[0002]

2. Description of the Related Art In general, when a resist pattern used in an etching process for manufacturing a semiconductor device is miniaturized, a pattern difference due to the density of the pattern, a rounding or receding phenomenon at an end portion of the pattern (optical proximity). This is called an effect). This optical proximity effect is illustrated in FIG.
As shown in FIG. 2B, during the exposure for pattern formation, a rectangular shape becomes round at the end of the resist pattern or becomes shorter than its original length as shown in FIG.

At the end of the pattern, light circulates from the side of the pattern to the end of the pattern and from the end of the pattern to the side of the pattern. When this becomes remarkable, the pattern does not satisfy the specified dimension, and the corners are rounded.

[0004] This phenomenon becomes more remarkable as the pattern dimension approaches the wavelength of the exposure light.
The retreat amount starts to increase from about m.

If this phenomenon occurs in the step of forming the gate of the transistor, a portion where the gate length of the transistor is shortened or a region where no gate exists is generated, and current always flows between the source and the drain. It can be.

[0006] The influence of the optical proximity effect has attracted attention from design rules of 0.5 μm or less, and most of them are countermeasures by correcting photomasks (rectiles), and in the field of OPC (Optical Proximity Correction). R & D is ongoing.

As one of the measures for correcting reticle, there is a technique called mask bias.

This is a method of simply extending the pattern of the reticle pattern in the direction opposite to the retreating direction to increase the dimension. However, if the pattern layout is not properly arranged, the chip area becomes large. In other words, if there is another pattern in the extended direction, the distance cannot be kept below a certain distance due to the resolution limit due to the resolution limit, so the extended pattern inevitably The area increases.

As another measure to avoid this, FIG.
As shown in (c), there is a method of correcting by adding a decoration pattern to an end of a reticle pattern (hereinafter, referred to as a corrected reticle). By adding the decoration pattern to the original pattern in this manner, it is possible to prevent the receding due to the light wraparound and to minimize the influence on the layout.

[0010]

In the case of making a correction reticle using the OPC method to compensate for the influence of the optical proximity effect described above, what size and where to place the decoration pattern is actually prototyped. The layout was determined by trial and error, or by the experience of a device engineer, and the time and labor required was enormous.

In particular, since a logic LSI that handles a random pattern tends to be significantly affected by the optical proximity effect, a decoration pattern must be arranged every time a reticle is created.

Accordingly, the present invention provides a reticle drawing by OPC (Optical Proximity Correction) at the time of forming a mask pattern in a semiconductor device manufacturing process which realizes a reduction in the time required for a layout operation when creating a reticle and simplification of the operation. It is an object of the present invention to provide a correction method of

[0013]

According to the present invention, in order to achieve the above object, a reticle pattern is formed by forming a square or a rectangular fine dot having a length of 1/5000 on one side according to a design rule. , And for each dot, the presence or absence of another dot adjacent to the dot is detected, and a dot to be corrected is selected in accordance with a predetermined surrounding dot arrangement state. Provided is a reticle drawing correction method for adding or deleting a modification pattern having a predetermined size and shape centered on a dot, and correcting so as to reduce the influence of the optical proximity effect.

The method of correcting the reticle drawing described above is as follows.
Based on the design rules, the reticle pattern is divided into square or rectangular fine dots, and for each dot, the presence or absence of another dot adjacent to the dot is detected, and a predetermined surrounding dot is detected. According to the dot arrangement state, select the dot at the end of the pattern,
This is a reticle pattern corrected by OPC so as to eliminate the influence of the optical proximity effect by adding or deleting a modification pattern of a predetermined size and shape centered on the dot.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Referring to FIG. 1, an outline of a method for correcting reticle drawing according to the present invention will be described.

As described above, the effect of the optical proximity effect is as follows.
As shown in FIG. 10B, this has a great effect on the end of the pattern, that is, on the corner. Therefore, in the present invention, a correct reticle pattern is formed by automatically adding or deleting an appropriate decorative pattern at the corner.

FIG. 1A shows a cross-shaped pattern shape as an example of a reticle before correction, and the L-shaped pattern 1 will be described. In this example, the end of the pattern is
Eight convex corners A1 to A8 and four concave corners B1
To B4. Of course, the combination of these corners differs depending on the pattern shape.

In this case, the corners A1 to A8 are rounded as shown by dotted lines, and the corners B1 to B4 are rounded so as to have no concave corners. Therefore, as a shape for correcting the cross-shaped pattern, correction is made to a correction reticle to which the modification pattern K is added or removed as shown in FIG.

A method of correcting reticle drawing according to the present invention for correcting the shape will be described.

FIG. 2 shows the corner A1 shown in FIG. 1A in detail, and the correction reticle will be described.

The lengths of the sides of the corners A1 and A2 in FIG.
The whole pattern is divided by a square dot having a length of / 5000 or a rectangular dot equivalent thereto, and the pattern is considered as an aggregate of dots.

In this embodiment, assuming that the length of the sides of the corners A1 and A8 is m, the length of one side of the dot is m / 50.
00 length. However, the length of one side of this dot is
It is affected by the pattern to be created and the manufacturing equipment used, and is an empirically determined arbitrary value.It is not fixed, and if it cannot be divided into squares due to the shape of the pattern, the dot will be a rectangle close to a square. It may be a dot.

A dot to which the decoration pattern K is added is selected from the pattern divided into a large number of dots. That is, in the pattern shown in FIG.
Eight dots at the corners A1 to A8 and four dots at the end of the corners B1 to B4 are selected. However, in terms of the shape of the corner, A1 = A2, A3 = A4, A5 = A6, A
7 = A8.

In the case of selection, one dot in the pattern is focused on as a target dot, and the state of the dot around the target dot itself is examined.
Normally, assuming that the noted dot is a2 in the dots shown in FIG. 2A, the upper (U), lower (D), right (R), left (L), upper right (UR), and lower right of the noted dot a2 (LR), upper left (UL), lower left (LL), there are dots in contact with each other, and a search is performed to determine which dot exists.

For example, the dot at the end of the corner A1 shown in FIG. In this case, FIG.
As shown in (a), the dot adjacent to the target dot a1 has three dots, namely, a dot D, a dot L, and a dot LL. In particular, two dots are in contact with two of the four sides. No other dots exist. When this pattern is obtained, a predetermined decoration pattern K is added.

Then, a modification pattern K as shown in FIG. 2B is added to the dot a1. This size is obtained empirically. In the present embodiment, when the size of the dot is 1/5000 of the design rule, the dot a
Along with the first side, a decoration pattern K having a rectangular shape extending up to the 1000th dot a1000 is added. The shape of the decoration pattern K may be a known shape, and the number of dots to be added is determined based on empirical data actually created in order to minimize the influence of the optical proximity effect. Is also good.

On the other hand, the corner B1 (B2) shown in FIG.
When the dot at the end of .about.B4) is searched for as a dot of interest, peripheral dots (modification pattern K) are deleted as shown in FIG. 3B.

Also in the case of deleting the periphery of the target dot b1, up to the 1000th dot b1000 is deleted along the four sides of the dot b1. The number of dots to be deleted is an arbitrary number of dots that minimizes the influence of the optical proximity effect.

FIG. 4 illustrates an example of a pattern in which a modification pattern must be added or deleted by dots at the end of a rectangular reticle pattern in relation to the corners shown in FIG.

FIG. 4A shows the pattern of the corners A1 and A2, FIG. 4B shows the pattern of the corners A3 and A4, and FIG.
(C) is a pattern of corners A5 and A6, and (d) of FIG.
This is a pattern of corners A7 and A8.

As a feature common to these dots a,
Another dot is adjacent to two sides of the four sides of the target dot that do not face each other, and one dot exists at a corner between them.

On the other hand, as a pattern example in which dots around the dot of interest must be deleted as the decoration pattern K, FIG.
FIG. 4F shows the pattern of the corner B2, and FIG.
FIG. 4H shows a pattern of a corner B4.

As a feature common to these dots b,
Another dot is adjacent to all four sides of the target dot, and another dot exists at three of the four corners. That is, there is no dot at one corner among the eight surrounding dots.

FIG. 5 shows a pattern in which addition and deletion of a modification pattern for correction is not performed.

As shown in FIGS. 5 (a) to 5 (d), in each of the target dots of each pattern, three out of the four sides of the target dot are adjacent to other dots, and two dots between them are provided.
There are other dots at one corner. In addition, in FIG. 5E, the target dot is a pattern completely surrounded by eight dots.

These attention dots are present on the sides of the pattern or inside the pattern. Therefore, the modification pattern K is not added or removed.

FIG. 6 shows a table serving as a criterion for adding or removing a decoration pattern to the noted dot described above.

This table is stored, for example, in a memory of a personal computer or the like, and a modification pattern K is added or deleted according to the designed reticle pattern.

The reticle pattern described above has a rectangular shape at the end.
There are also oblique patterns as shown in FIG. In such a case, assuming that the dot at the end is the attention dot c1, the upper (U), left (L), upper left (UL),
Another dot exists at the lower left (LL).

The feature of the target dot C1 is that there are other dots adjacent to two of the four sides of the target dot, similarly to the pattern a1 shown in FIG.

Therefore, it is possible to add the decoration pattern K using the same conditions in the table as for the pattern a.

The method of adding the modification pattern K is shown in FIG.
As shown in FIG. 2B, an addition is performed to the observable dot of the oblique pattern so as to project into a rectangle as shown in FIG. 2B.

Next, a method for correcting reticle drawing will be described with reference to the flowchart shown in FIG. 8 and the pattern shown in FIG.

First, the entire pattern is divided into 1/5000 squares or rectangular dots according to the reticle pattern shown in FIG. 9 based on design rules (step S1).

Next, the divided dots are sequentially referred to the table as the target dots, and it is detected whether or not another dot is adjacent to all four sides of the target dot (step S).
2). Here, if another dot is adjacent to all four sides of the target dot (YES), it is detected whether or not another dot exists at all four corners of the target dot (step S3). .

If there are other dots at all four corners of this dot of interest (YES), the pattern is the one shown in FIG. 5E, and the process ends without adding or deleting a decoration pattern.

On the other hand, if no other dot exists at all four corners (NO), it is detected whether or not another dot exists at all three corners of the target dot (step S4). ). Here, when another dot exists at all three corners (YES), it corresponds to the dot d2 shown in FIG. 9A, and contacts with the side counted from the target dot d2 as shown in FIG. 9B. A decoration pattern D2 from which 1000 dots have been deleted is formed (step S5).

On the other hand, if no other dot exists at all three corners of the target dot (YES), it is notified as an error because it does not exist in a pattern (step S6).

In step S2, when no other dot is adjacent to all four sides of the target dot (N
O) It is detected whether or not another dot is adjacent to all three sides of the target dot (step S7). Here, if another dot is adjacent to all three sides of the target dot (YES), the patterns are those shown in FIGS. 5A to 5D, and the modification pattern is not added or deleted. finish.

On the other hand, if no other dot is adjacent to all three sides of the target dot (NO), it is detected whether or not another dot is adjacent to the two sides of the target dot (step). S8).

If another dot is adjacent to two sides of the target dot (YES), the dot d shown in FIG.
1, d3, d4, d5, and d6, and modification patterns D1, D3, D4, and D5 added with 1000 dots counted from each target dot and in contact with sides as shown in FIG.
D6 is formed (Step S9). On the other hand, when no other dot exists on the two sides of the target dot (NO),
Since it does not exist in a pattern, it is notified as an error (step S6).

In the above-described embodiment, the size of the dot is set to 1/5000 and the size of the decoration pattern is set to 1000 dots based on the design rule. However, the present invention is not limited to this. May be. If the dots are further refined and set to 1/10000,
The size of the decoration pattern may be set to 10000 dots.

As described above, according to the present embodiment, the reticle pattern is divided into square or rectangular fine dots based on the design rules, and each dot is divided into adjacent dots. The presence / absence of the dot is detected, the table is referred to, and the dot at the end of the pattern to which the decoration pattern is added or deleted is selected. A modification pattern having a predetermined size and shape can be added or deleted around the selected dot, and the corrected reticle pattern that eliminates the influence of the optical proximity effect can be easily corrected.

In the present embodiment, the addition or deletion of the decoration pattern is performed by paying attention to all the dots that divide the pattern. However, when this is actually performed, it takes much time. Become.

Therefore, for example, a reticle pattern is captured as an image, the edge of the pattern of the image is detected by a known method, the position (two-dimensional coordinates) of the end of the pattern is specified, and the end of the pattern is identified. After paying attention to the dots near the leading end, the dots are selected only by focusing on those dots or the dots in the vicinity, it is possible to efficiently determine whether to add or delete the decoration pattern, and to easily shorten the processing time. .

[0057]

As described above in detail, according to the present invention, the time required for the layout work at the time of reticle creation can be reduced and the mask pattern can be formed in the manufacturing process of the semiconductor device realizing the simplification of the work. A method of correcting reticle drawing by OPC can be provided.

[Brief description of the drawings]

FIG. 1 is a pattern example for explaining an outline of a reticle drawing correction method according to the present invention.

FIG. 2 is a diagram illustrating an example of a pattern for explaining the addition of a decoration pattern on a target dot.

FIG. 3 is a diagram illustrating an example of a pattern for explaining deletion of a decoration pattern in a target dot.

FIG. 4 is a diagram showing an example of a pattern to which a modification pattern must be added or deleted.

FIG. 5 is a diagram showing an example of a pattern in which addition and deletion of a decoration pattern is not performed;

FIG. 6 is a diagram showing a table serving as a criterion for adding or removing a decoration pattern to a target dot.

FIG. FIG. 9 is a diagram illustrating an example of a reticle pattern for describing a correction method for an oblique pattern.

FIG. 8 is a flowchart for explaining a reticle drawing correction method according to the embodiment;

FIG. 9 is a pattern example for describing a reticle correction method according to the present embodiment along the flowchart shown in FIG. 8;

FIG. 10 is a diagram showing roundness of a resist pattern edge generated by a conventional technique and a correction reticle for preventing the roundness.

[Explanation of symbols]

 a1, b1 ... dot of interest K ... decoration pattern A1-A8, B1-B4 ... corner

Claims (6)

[Claims] 1. A reticle pattern is divided into square or rectangular fine dots, and the presence or absence of another dot adjacent to the dot is detected for each dot. Depending on the arrangement of the dots,
A dot to be corrected is selected, and a modification pattern of a predetermined size and shape is added or deleted around the dot, and correction is performed so as to reduce the influence of the optical proximity effect. Correction method. 2. The method of correcting reticle drawing, wherein a length of one side of the dot is determined based on a design rule.
2. The method according to claim 1, wherein the length is 1/5000. 3. The method of correcting reticle drawing according to claim 1, wherein the other dots arranged around the dot of interest as a detection target are two dots out of the four sides of the attention dot which are not opposed to each other. If they were adjacent,
2. The method according to claim 1, wherein the modification pattern is added.
3. The method for correcting reticle drawing according to 1. 4. The method of correcting reticle drawing according to claim 1, wherein the other dots arranged around the dot of interest as the detection target are adjacent to all four sides of the noted dot, The method according to claim 1, wherein when another dot exists at three corners, the dot corresponding to the decoration pattern is deleted. 5. The method of correcting reticle drawing, wherein when the length of one side of the dot is 1/5000, the length of the side of the decoration pattern to be deleted is centered. 3. The method according to claim 2, wherein the length of the reticle is 1000 dots along a diagonal line of the dots. 6. A method for correcting a reticle drawing, comprising the steps of: determining whether a noted dot is a dot to which the decoration pattern is added or deleted; 2. The reticle drawing correction method according to claim 1, wherein the dot arrangement state is stored in a table, and a target dot is selected by referring to the table.