阅读说明：本技术 一种基于应力阻尼调节的光刻工艺热点修正方法及系统 (Photoetching process hot spot correction method and system based on stress damping adjustment ) 是由 尉海清 刘世元 江浩 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种基于应力阻尼调节的光刻工艺热点修正方法及系统,其方法包括：获取掩模图案的标记热点；以标记热点为中心在掩模版上形成N个由内至外的环形带；将位于各环形带中的掩模图案的顶点沿偏离标记热点的方向移动特定距离,并将移动后的顶点按照原连接关系连接,得到更新布图；对更新布图进行电气特性的验证,判断更新布图的电气特性的偏差是否处于可容忍范围内,若否,则进行几何修正以补偿电参数的偏差后结束修正,若是,则结束修正。通过定位标记热点并将以标记热点为中心的布局区域划分为多个环形带,通过移动环形带内的掩模图案顶点来增大热点区域内掩模图案之间的间距,从而消除热点且不改变掩模图案整体的电学特性。(The invention discloses a photoetching process hotspot correction method and a photoetching process hotspot correction system based on stress damping adjustment, wherein the method comprises the following steps: acquiring a mark hot spot of a mask pattern; forming N annular bands from inside to outside on the mask plate by taking the mark hot spot as a center; moving the vertexes of the mask patterns in the annular belts by a specific distance along the direction deviating from the marking hot spot, and connecting the moved vertexes according to the original connection relation to obtain an updated layout; and verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters, and then finishing the correction, and if so, finishing the correction. By locating the marking hot spot and dividing the layout area centered on the marking hot spot into a plurality of annular bands, the pitch between the mask patterns in the hot spot area is increased by moving the mask pattern vertices in the annular bands, thereby eliminating the hot spot without changing the overall electrical characteristics of the mask patterns.)

1. A photoetching process hot spot correction method based on stress damping adjustment is characterized by comprising the following steps:

step 1: acquiring a mark hot spot of a mask pattern;

step 2: forming N concentric closed graphs with the mark hot spot as the center, wherein the N concentric graphs form N annular bands with the number gradually increasing from the inner ring to the outer ring on the mask plate;

and step 3: moving the top points of the mask patterns in the annular bands for a specific distance along the direction deviating from the marking hot point, and connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout;

and 4, step 4: and verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters, and then finishing the correction, and if so, finishing the correction.

2. The method of claim 1, wherein the closed figure is one of a circle, a rectangle, or a regular polygon.

3. The lithography process hotspot correction method of claim 1, wherein the vertex in the kth annular zone is moved by a specific distance d_kAnd (N-k) epsilon, wherein epsilon is a preset moving step.

4. The method of claim 1, wherein moving the vertices of the mask pattern in each annular zone a specified distance in a direction away from the marking hotspot comprises moving each vertex individually or moving a line segment containing the vertices in the annular zone as a whole.

5. The method of claim 1, wherein the closed figure is a circle, the annular band is a circular ring, and the vertex is moved a specific distance in a direction away from the mark hotspot, comprising: each vertex is moved a certain distance in a direction from the marking hotspot to the vertex.

6. The method of claim 1, wherein the closed figure is a rectangle, the annular band is a rectangular ring, and the vertex is moved a specific distance in a direction away from the mark hotspot, comprising: each vertex is moved a certain distance in a direction perpendicular to the nearest rectangular side.

7. The lithography process hot spot correction method as claimed in claim 1, wherein when the mask pattern in the annular band includes an arc-shaped line, the arc-shaped line is divided into step-shaped line segments, and the apex of the step-shaped line segment is moved.

8. The method of claim 1, wherein the mask pattern comprises a plurality of discontinuous sub-patterns, and when the mark hot spot is located on any sub-pattern, the vertices of the sub-patterns other than the sub-pattern where the mark hot spot is located are selected to move.

9. The lithography process hotspot correction method of claim 1, wherein when a plurality of hotspots are obtained on the reticle, each hotspot corresponds to a hotspot area, one of the hotspots is selected as a mark hotspot, pairwise overlapping areas of all hotspots are determined, and vertices outside the overlapping areas are selected for movement.

10. A photoetching technology hot spot correction system based on stress damping adjustment is characterized by comprising the following components:

the hot spot acquisition unit is used for acquiring a marking hot spot of the mask pattern;

the region dividing unit is used for forming N concentric closed graphs with the mark hot spot as the center, and the N concentric graphs form N annular bands with the number gradually increasing from the inner part to the outer part on the mask plate;

the moving unit is used for moving the top points of the mask patterns in the annular bands for a specific distance along the direction deviating from the marking hot point, and connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout;

and the verification unit is used for verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters and then finishing the correction, and if so, finishing the correction.

Technical Field

The invention belongs to the technical field of semiconductor manufacturing, and particularly relates to a photoetching process hotspot correction method and system based on stress damping adjustment.

Background

Semiconductor Integrated Circuits (ICs) are the core of the electronic information industry, and with the rapid development of the internet industry, Integrated circuits are becoming more and more important, while photolithography is one of the core technologies in large-scale Integrated Circuit fabrication, and its task is to transfer a mask pattern onto a photoresist coated on a silicon wafer, which represents the advanced degree of the fabrication process, and directly determines the minimum pattern size that can be fabricated, and thus the performance of the Integrated Circuit.

With the continuous reduction of the technical nodes, when the critical dimension of the lithography pattern is below the wavelength of the adopted illumination light source, the lithography imaging system has an Optical Proximity Effect (OPE) phenomenon, which causes the exposure pattern formed on the silicon wafer to have a certain distortion compared with the adopted mask pattern, so that the mask pattern needs to be optimally designed in advance, and Optical Proximity Correction (OPC) is performed, so that the exposure pattern obtained on the silicon wafer is closer to the target pattern.

In the actual sub-wavelength lithography process, because the value of the designed CD is far smaller than the wavelength, after the OPC layout is corrected, the space between mask patterns is reduced by excessive OPC correction, so that defects such as open circuit (ping) and bridging (bridge) are generated on the exposure pattern on an actual silicon wafer, and the defect areas are called lithography process hot spot areas, which are referred to as lithography process hot spots or hot spots for short. The hot spots of the photolithography process may affect the circuit performance of the device, and even cause the actual circuit function to be completely changed, resulting in the ic failing to be taped out.

Disclosure of Invention

In view of the above defects or improvement requirements of the prior art, the present invention provides a method and a system for correcting hot spots of a lithography process based on stress damping adjustment, which aims to eliminate hot spots of a mask pattern, thereby solving the technical problem that exposure patterns on actual silicon wafers have defects such as open circuits (ping) and bridges (bridge) due to the hot spots of the mask pattern.

In order to achieve the above object, according to an aspect of the present invention, there is provided a method for correcting a hot spot in a lithography process based on stress damping adjustment, including:

step 1: acquiring a mark hot spot of a mask pattern;

step 2: forming N concentric closed graphs with the mark hot spot as the center, wherein the N concentric graphs form N annular bands with the number gradually increasing from the inner ring to the outer ring on the mask plate;

and step 3: moving the top points of the mask patterns in the annular bands for a specific distance along the direction deviating from the marking hot point, and connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout;

and 4, step 4: and verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters, and then finishing the correction, and if so, finishing the correction.

Preferably, the closed figure is one of a circle, a rectangle or a regular polygon.

Preferably, the vertices within the kth annular band are moved by a certain distance d_kAnd (N-k) epsilon, wherein epsilon is a preset moving step.

Preferably, the moving the vertices of the mask pattern located in each annular zone by a specific distance in a direction away from the marking hot spot includes moving each vertex individually, or moving a line segment containing the vertices located in the annular zone as a whole.

Preferably, the closed figure is a circle, the annular band is a circular ring, and the vertex moves a specific distance in a direction deviating from the marking hot spot, including: each vertex is moved a certain distance in a direction from the marking hotspot to the vertex.

Preferably, the closed figure is a rectangle, the annular band is a rectangular ring, and the vertex moves a specific distance in a direction away from the marking hot spot, including: each vertex is moved a certain distance in a direction perpendicular to the nearest rectangular side.

Preferably, when the mask pattern in the annular band includes an arc-shaped line, the arc-shaped line is divided into step-shaped line segments, and the vertex of the step-shaped line segment is moved.

Preferably, the mask pattern comprises a plurality of discontinuous sub-patterns, and when the marking hot spot is located on any sub-pattern, the vertex on the other sub-patterns except the sub-pattern where the marking hot spot is located is selected to move.

Preferably, when a plurality of hot spots are acquired on the mask, each hot spot corresponds to one hot spot area, one hot spot is selected as a mark hot spot, the overlapping area of every two hot spots is determined, and the top points outside the overlapping area are selected to move.

According to another aspect of the present invention, there is provided a lithography process hot spot correction system based on stress damping adjustment, comprising:

the hot spot acquisition unit is used for acquiring a marking hot spot of the mask pattern;

the region dividing unit is used for forming N concentric closed graphs with the mark hot spot as the center, and the N concentric graphs form N annular bands with the number gradually increasing from the inner part to the outer part on the mask plate;

the moving unit is used for moving the top points of the mask patterns in the annular bands for a specific distance along the direction deviating from the marking hot point, and connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout;

and the verification unit is used for verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters and then finishing the correction, and if so, finishing the correction.

Generally speaking, compared with the prior art, by the above technical solution contemplated by the present invention, by locating the mark hot spot and dividing the layout area centered on the mark hot spot into a plurality of annular bands, the pitch between the mask patterns in the hot spot area is increased by moving the mask pattern vertices in the annular bands, i.e. by adjusting the stress damping of the layout, thereby eliminating the hot spot without changing the overall electrical characteristics of the mask pattern. The present invention repairs each hotspot by modifying its local layout in the vicinity of it only, without using physical design tools, such as changing placement and routing (typically involving RC extraction and timing analysis), greatly reducing the amount of work required and increasing the efficiency of hotspot repair.

Drawings

FIG. 1 is a flowchart illustrating the steps of a hot spot correction method for a lithography process based on stress damping adjustment according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating the steps of a hot spot correction method for a lithography process based on stress damping adjustment according to another embodiment of the present invention;

FIG. 3 is a schematic diagram of a mask pattern and a mark hot spot region in one embodiment of the present invention;

FIG. 4 is a schematic diagram of the circular division of the local area around the marked hot spot according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of the square division of the local area around the mark hot spot according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of the segmentation of an arc segment in an example of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Fig. 1 is a flowchart illustrating steps of a method for correcting a hot spot in a lithography process based on stress damping adjustment according to an embodiment of the present invention, where the method includes:

step S100: a mark hot spot of the mask pattern is acquired.

Step S200: n concentric closed graphs with the mark hot spot as the center are formed, and N annular bands with the number gradually increasing from the inner ring to the outer ring are formed on the mask plate by the N concentric graphs.

Step S300: and moving the top points of the mask patterns in the annular bands by a specific distance along the direction deviating from the marking hot point, connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout.

Step S400: and verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters, and then finishing the correction, and if so, finishing the correction.

The respective steps will be described in detail below.

For step S100: and acquiring a marking hot spot for acquiring the mask pattern.

In one embodiment, the hot spot of the mask pattern can be automatically detected by auxiliary software, and the auxiliary software can detect the hot spot region, wherein the hot spot is positioned in the center of the hot spot region. In one embodiment, when there are multiple hotspots, one of the hotspots is selected as a mark hotspot.

In one embodiment, the mask pattern is a mask pattern that has been subjected to OPC and lithography verification. As shown in fig. 3, the pattern 11 to be formed is subjected to OPC and photolithography verification to obtain a mask pattern 12, i.e. a design pattern, wherein the pattern to be formed is a pattern to be formed on a silicon wafer. Only a partial pattern is shown in the figure. The distance between the line edges in the circled portions in the mask pattern 12 becomes significantly narrow and even bridging defects occur, which have an effect on circuit performance. Therefore, the mask pattern 12 cannot be directly used as a mask, and it is necessary to repair it. In this embodiment, the area surrounded by the circle is a mark hot spot area 13, and the center point thereof is a mark hot spot 14.

For step S200: n concentric closed graphs with the mark hot spot as the center are formed, and N annular bands with the number gradually increasing from the inner ring to the outer ring are formed on the mask plate by the N concentric graphs.

In one embodiment, the N concentric closed figures are identical in shape. In an embodiment, the closed figure may be one of a circle, a rectangle, or a regular polygon. In one embodiment, the width of each annular band is the same, and may be referred to as W.

In one embodiment, the closed figure is a circle, and the formed annular band is a circular ring, as shown in fig. 4, a circle is made with a mark hot spot (not marked in the figure) as a center, a plurality of circular rings are formed, and the circle at the innermost circle can be regarded as a circular ring with an inner diameter of 0. A two-dimensional coordinate axis can be established by taking the marked hot spot as an origin, coordinates of each point on the mask are expressed as (x, y), and then, the kth annular band (k is more than or equal to 0)<N) can be defined as kW ≦ (x)²+y²)^1/2<(k +1) W, where W is the width of each band, R is the radius of the circular area divided into N annular bands, and R — NW. In fig. 4, the inner and outer rings 21, 22 and 23 are shown. Fig. 4 is a partial schematic view, and is not a whole view.

In one embodiment, the closed figure is a square and the annular band formed is a square ring. As shown in fig. 5, a square is formed by centering on a mark hot spot (not shown) to form a plurality of square rings, and the square at the innermost circle can be regarded as a square ring with an inner diameter of 0. The two-dimensional coordinate axis can be established with the marked hot spot as the origin and the coordinates of each point on the reticle are expressed as (x, y), then the kth band (0 ≦ k < N) can be defined as kW ≦ x | < (k +1) W and kW ≦ | y | < (k +1) W, where W is the width of each band, R is half the side length of the square area divided into N square rings, and R is NW. In fig. 5, a rectangular ring 31, a rectangular ring 32 and a rectangular ring 33 are shown. Fig. 5 is a partial schematic view, and is not a whole view.

In this embodiment, W is 100nm, N is 100, and R is 10 um.

For step S300, moving the vertices of the mask pattern in each circular band by a specific distance in the direction deviating from the marked hot spot, and connecting the moved vertices according to the original connection relationship to obtain an updated layout, where the distance moved by each vertex decreases with the increase of the number of rings in the circular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout.

Wherein, the tolerable deviation of the layout electrical design is a value calculated in advance.

In one embodiment, the vertex of the mask pattern in each annular zone is moved in a direction deviating from the marking hot spot, and the specific moving direction can be flexibly configured according to actual conditions as long as the line pitch in the original hot spot region is increased after the movement.

In one embodiment, moving the vertices of the mask pattern located in each annular band a particular distance in a direction away from the marking hot spot comprises moving each vertex individually.

As shown in FIG. 4, the annular bands are circular rings, each having a plurality of vertices therein, each vertex being moved independently, and then the vertices being connected in a pattern according to the original connection feature. The vertices are moved a specific distance in a direction away from the marking hotspot, in particular, each vertex is moved a specific distance in a direction (radial) from marking hotspot to vertex. With continued reference to FIG. 4, the direction of movement of vertex A is then the direction from the marked hotspot toward vertex A, i.e., the direction of the dashed arrow in FIG. 4.

As shown in FIG. 5, the annular bands are rectangular rings with multiple vertices within each band, each vertex is moved independently, and then the vertices are connected in a pattern according to the original connection features. The vertices are moved a specific distance in a direction away from the marked hot spot, specifically, each vertex is moved a specific distance in a direction perpendicular to the nearest rectangular edge. With continued reference to FIG. 5, the direction of movement of the vertex A is then vertically downward in the figure, i.e., in the direction of the dashed arrow in FIG. 5.

In one embodiment, moving the vertices of the mask pattern located in each annular band a particular distance in a direction away from the marking hot spot includes moving the line segments with vertices within each annular band in their entirety. That is, the entire (sub-) segment within a band is displaced as a whole in any case, whether the line segment is completely within a band or one or both ends of the line segment are interrupted by the border line of the band.

In one embodiment, the vertices within the kth ring band are moved a certain distance d_kAnd (N-k) epsilon, epsilon is a very small positive number, depending on the actual situation. In this particular embodiment, ε is 1 nm.

In an embodiment, the mask pattern includes a plurality of discontinuous sub-patterns, that is, the mask pattern includes a plurality of unconnected sub-patterns, when the mark hot spot is located on any sub-pattern, the vertex of the sub-pattern where the mark hot spot is located does not move, and the vertices on the other sub-patterns except the sub-pattern where the mark hot spot is located are selected to move.

In one embodiment, when a plurality of hot spots are acquired on a mask, each hot spot corresponds to one hot spot area, one hot spot is selected as a mark hot spot, pairwise overlapping areas of all the hot spots are determined, vertexes located in the overlapping areas do not move, and vertexes outside the overlapping areas are selected to move.

In one embodiment, as shown in FIG. 6, when the mask pattern in the annular band contains lines with insignificant angles, and no more distinct polygon vertices can be found, these "irregular" line segments can be divided into a series of combinations of line segments with specific angles, for example, the arc line 15 is changed into a combination of horizontal and vertical lines to form a step line segment 16, and the step line segment 16 is moved.

In step S400, the electrical characteristics of the updated layout obtained in the above steps are verified, and it is determined whether or not the deviation of the electrical characteristics of the updated layout is within a tolerable range, and if not, the correction is terminated after the geometric correction is performed to compensate for the deviation of the electrical parameters, and if so, the correction is terminated.

In one embodiment, the RC extraction tool is used to verify the electrical characteristics of the updated layout pattern, and determine whether the deviation of the electrical characteristics of the updated layout pattern is within a tolerable range, for example, within a tolerance range, if the variation of the electrical characteristics exceeds the tolerance range, the error caused by the correction is necessary, and further geometric modification, for example, fine-tuning the dimension or rounding the dense zigzag lines, may be performed after the stress damping under the guidance of the RC extraction tool to compensate the deviation of the electrical parameters until the final stress damping and the modified layout are equal to the original layout.

In an embodiment, as shown in fig. 2, step S400 may specifically include the following sub-steps:

step S410: the electrical characteristics of the updated layout are verified.

Step S420: determining whether the deviation of the electrical characteristics of the updated layout is within a tolerable range:

if not, go to step S430, and if so, go to step S440.

Step S430: a geometric correction is performed to compensate for the deviation of the electrical parameter.

Step S440: continuously detecting whether hot spots exist, and if so, jumping to the step S100; if not, go to step S450.

Step S450: and finishing the correction.

In this embodiment, the layout is repeatedly optimized to completely eliminate the hot spot by setting a loop process.

In the invention, the hot spot is positioned, the layout area taking the hot spot as the center is divided into a plurality of annular bands, and the distance between the mask patterns in the hot spot area is increased by moving the top points of the mask patterns in the annular bands, so that the hot spot is eliminated without changing the overall electrical characteristics of the mask patterns. The present invention repairs each hotspot by modifying its local layout in the vicinity of it only, without using physical design tools, such as changing placement and routing (typically involving RC extraction and timing analysis), greatly reducing the amount of work required and increasing the efficiency of hotspot repair.

The invention also relates to a photoetching process hotspot correction system based on stress damping adjustment, which comprises the following steps:

the hot spot acquisition unit is used for acquiring a marking hot spot of the mask pattern;

the region dividing unit is used for forming N concentric closed graphs with the mark hot spot as the center, and the N concentric graphs form N annular bands with the number gradually increasing from the inner part to the outer part on the mask plate;

the moving unit is used for moving the top points of the mask patterns in the annular bands for a specific distance along the direction deviating from the marking hot point, and connecting the moved top points according to the original connection relation to obtain an updated layout, wherein the moving distance of each top point is reduced along with the increase of the number of the rings of the annular band, and the specific distance does not exceed the tolerable deviation of the electrical design of the layout;

and the verification unit is used for verifying the electrical characteristics of the updated layout, judging whether the deviation of the electrical characteristics of the updated layout is within a tolerable range, if not, performing geometric correction to compensate the deviation of the electrical parameters and then finishing the correction, and if so, finishing the correction.

Specifically, the functions of the units of the system correspond to the photolithography hot spot correction method one to one, and are not described herein again.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.