CN112764307A

CN112764307A - Optical proximity effect correction method

Info

Publication number: CN112764307A
Application number: CN201911075153.1A
Authority: CN
Inventors: 不公告发明人
Original assignee: Changxin Memory Technologies Inc
Current assignee: Changxin Memory Technologies Inc
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2021-05-07

Abstract

The invention provides a method for correcting optical proximity effect, which comprises the following steps: providing at least one group of characteristic graph data, wherein the characteristic graph data corresponds to a characteristic graph; manufacturing a detection pattern on the photomask according to the characteristic pattern data; comparing the detection pattern with the characteristic pattern, and obtaining the manufacturing capability of the photomask according to the comparison result; and correcting the optical proximity effect according to the manufacturing capability of the photomask. The invention has the advantages that the manufacturing capability of the photomask is considered in the correction of the optical proximity effect, and the correction precision of the optical proximity effect is further improved.

Description

Optical proximity effect correction method

Technical Field

The invention relates to the field of integrated circuit manufacturing, in particular to a method for correcting an optical proximity effect.

Background

In the prior art, in order to transfer the pattern of the integrated circuit onto the wafer (wafer) smoothly, the circuit pattern is first designed into a mask pattern, and then the mask pattern is transferred from the surface of the mask onto the wafer through the exposure stage. Including but not limited to silicon, silicon germanium (Site), Silicon On Insulator (SOI), and various combinations thereof.

For an integrated circuit, the pattern is designed with a specific size, and if the size of the pattern formed on the wafer does not meet the requirement, the performance of the integrated circuit is affected, and even the integrated circuit is directly scrapped.

One of the reasons for affecting the pattern on the wafer is the mask pattern on the mask surface, and the fabrication capability of the mask itself is one of the important factors affecting the mask pattern. If the manufacturing capability of the photomask can be detected, the photomask pattern can be corrected correspondingly according to the manufacturing capability of the photomask, and the photomask pattern meeting the requirement can be obtained.

Therefore, considering the manufacturing capability of the mask in the optical proximity correction is a technical problem to be solved.

Disclosure of Invention

The invention aims to provide a method for correcting an optical proximity effect, which improves the correction precision of the optical proximity effect.

In order to solve the above technical problem, the present invention provides a method for correcting an optical proximity effect, including: providing at least one group of characteristic graph data, wherein the characteristic graph data corresponds to a characteristic graph; manufacturing a detection pattern on the photomask according to the characteristic pattern data; comparing the detection pattern with the characteristic pattern, and obtaining the photomask manufacturing capacity according to the comparison result; and forming OPC data according to the manufacturing capability of the photomask, and correcting the chip graph formed on the photomask according to the OPC data.

Further, the characteristic pattern has the same characteristic information as a chip pattern to be formed on the photomask.

Further, the characteristic information at least comprises a critical dimension of the pattern, a space of the pattern and a gap of the pattern.

Further, the characteristic pattern is a pattern subjected to OPC correction or a pattern not subjected to OPC correction.

Furthermore, the detection pattern is manufactured on the non-exposure area of the photomask.

Further, the photomask comprises a chip area and a cutting path area surrounding the chip area, and the non-exposure area is located at the periphery of the cutting path area of the photomask.

Furthermore, the pattern of the chip area, the pattern of the dicing street area and the pattern of the non-exposure area of the photomask are formed in the same process, and the pattern of the non-exposure area comprises the detection pattern.

Further, establishing a database of the manufacturing capabilities of the reticles, the database comprising the manufacturing capabilities of the reticles for a plurality of reticle factories; when a certain photomask factory is adopted to manufacture the photomask, the manufacturing capability of the photomask corresponding to the photomask factory is selected to form OPC data.

Further, the database also includes the fabrication capabilities of the different features fabricated by a single reticle fab.

Further, the manufacturing capability of the photomask comprises the difference size or difference area between the feature pattern and the detection pattern.

The invention has the advantages that the manufacturing capability of the photomask is considered in the correction of the optical proximity effect, and the correction precision of the optical proximity effect is further improved.

Drawings

FIG. 1 is a schematic diagram illustrating the steps of one embodiment of the method for correcting optical proximity effect according to the present invention;

FIGS. 2A-2F are schematic diagrams of characteristic patterns in the method for correcting optical proximity effect according to the present invention;

FIG. 3 is a schematic diagram of a mask.

Detailed Description

The following describes in detail a specific embodiment of the method for correcting optical proximity effect provided by the present invention with reference to the accompanying drawings.

Different photomask factories have different photomask manufacturing capabilities due to differences in equipment, technology and the like, and finally, the formed photomask patterns have great differences. When Optical Proximity Correction (OPC) is performed, if Correction is performed using the same set of Correction data or model, a mask pattern that satisfies the Correction accuracy requirement cannot be obtained.

In view of the above, the present invention provides a method for correcting optical proximity effect, which takes into account the capability of the reticle factory to fabricate the reticle. According to the difference of the capability of manufacturing the photomask, the photomask manufacturer can be screened, or the corresponding OPC data is adopted to correct the photomask pattern, so as to obtain the photomask pattern meeting the requirement.

FIG. 1 is a schematic diagram illustrating steps of a method for correcting optical proximity effect according to an embodiment of the present invention. Referring to fig. 1, the method for correcting the optical proximity effect includes the following steps: step S20, providing at least one group of characteristic graph data, wherein the characteristic graph data corresponds to a characteristic graph; step S21, manufacturing a detection pattern on the photomask according to the characteristic pattern data; step S22, comparing the detection pattern with the characteristic pattern, and obtaining the mask making capacity according to the comparison result; and step S23, forming OPC data according to the manufacturing capability of the photomask, and correcting the chip pattern formed on the photomask according to the OPC data.

Specifically, referring to fig. 1, the method for correcting the optical proximity effect includes the following steps:

and step S20, providing at least one group of characteristic graph data, wherein the characteristic graph data corresponds to the characteristic graph. The feature data is a layout file having a specific file format (e.g., GDS format) and is provided to a reticle Shop (Mask Shop). The feature pattern data may include a plurality of sets of pattern data, and each set of pattern data may correspond to a set of feature patterns.

The characteristic pattern has the same or similar characteristic information as the chip pattern to be formed on the photomask. The feature information includes at least a Critical Dimension (CD) of the pattern, a pitch (pitch) of the pattern, and a space (gap) of the pattern.

Several feature patterns and their associated feature information are exemplified below.

FIG. 2A is a first type of feature, which is a Main line-assistant line pattern (Main-AF), referring to FIG. 2A. The characteristic information of the main line 30 and the auxiliary line 31 is shown in table 1.

TABLE 1

Fig. 2B is a second type feature pattern, which is a Line-macro (Line-macro) pattern, please refer to fig. 2B. The characteristic information of the line 32 and the macro 33 is shown in table 2.

TABLE 2

FIG. 2C shows a third type of feature, which is a 3-stripe (3-bars) pattern, with reference to FIG. 2C. The characteristic information of the stripes 34 is shown in table 3.

TABLE 3

Type (B)	Critical dimension cd Range (nm)	Range of pitch (nm)	Space range (nm)
				Stripe	10～120	80～800	10～200

FIG. 2D is a fourth type of feature graph, which is a dense end-to-end (Dence EPE) graph, see FIG. 2D. Characteristic information of the bar pattern 35 is as shown in table 4.

TABLE 4

Type (B)	Critical dimension cd Range (nm)	Range of pitch (nm)	Space range (nm)
				Dense end-to-end	40～80	80～800	12～120

Fig. 2E is a fifth type of feature pattern, see fig. 2E, which is an end-to-end (Iso E2E) pattern. Characteristic information of the bar pattern 36 is as shown in table 5.

TABLE 5

Type (B)	Critical dimension cd Range (nm)	Space range (nm)
			Head to head	10～120	10～200

Fig. 2F is a sixth type of feature pattern, which is a Staircase (cascade) pattern, please refer to fig. 2F. The characteristic information of the step pattern 37 is as shown in table 6.

TABLE 6

Type (B)	Critical dimension cd Range (nm)	Range of pitch (nm)	Gap range (nm)
				Stair	10～120	80～800	20～120

It will be appreciated that the above lists only a few types of feature patterns and their feature information, and that other patterns in the integrated circuit may be used as the feature pattern.

Wherein, the characteristic graph is a graph which is subjected to OPC correction or a graph which is not subjected to OPC correction.

Referring to step S21 and fig. 3, a detection pattern is formed on the mask according to the feature pattern data. And the photomask factory extracts relevant characteristic pattern data from the layout file and manufactures a detection pattern on the photomask according to the characteristic pattern data. Fig. 3 is a schematic diagram of a photomask, where the photomask includes a chip region 40, a scribe line region 41 surrounding the chip region 40, and the non-exposure region 42 located at the periphery of the scribe line region 41.

In the present embodiment, the detection pattern 49 is formed in the non-exposure region 42 of the mask, and the position of the detection pattern 49 is indicated by a dashed line in fig. 3 to avoid affecting the patterns of the chip region 40 and the scribe line region 41. Further, the detection patterns 49 may be distributed at different positions of the non-exposure region 42 to fully utilize the non-exposure region 42. In other embodiments of the present invention, the inspection pattern 49 may be formed in other regions of the mask.

Further, when the detection pattern 49 is formed in the non-exposure region 42, another pattern may be formed in the chip region 40 and the scribe line region 41 at the same time. Since the inspection pattern 49 is used only for inspecting the capability of manufacturing a mask, it is not necessary to form another pattern on the mask in order to simplify the process and save the cost when the inspection pattern is formed.

In step S22, the inspection pattern is compared with the feature pattern, and the mask-making capability is obtained according to the comparison result. If the difference between the detected pattern and the feature pattern is within the error range, the mask manufacturing capability is stronger and meets the requirement, and if the difference between the detected pattern and the feature pattern is not within the error range, the mask manufacturing capability is weaker and cannot meet the requirement, further adjustment is needed, for example, the mask manufactured by the mask factory is not manufactured by the mask factory, or the mask manufactured by the mask factory is corrected by correction data.

Further, the manufacturing capability of the photomask comprises the difference size or difference area between the feature pattern and the detection pattern. For example, as shown in FIG. 2B, the critical dimension of the line 32 in the second type feature pattern is different from the critical dimension of the line in the second type inspection pattern on the reticle manufactured by the reticle foundry by 5nm, the length of the line is 1000nm, and the difference area of the line is 5000nm²。

Further, the method for correcting the optical proximity effect of the present invention further includes a step of forming OPC data according to the manufacturing capability of the mask and correcting the chip pattern formed on the mask according to the OPC data in step S23. Since the photomask factories have different abilities to manufacture photomasks and different errors of the manufactured photomasks, if all the photomasks manufactured by the photomask factories are corrected by using the same OPC correction data, the obtained photomasks may not meet the preset requirements. Therefore, the mask factories with different mask making capacities can be corrected by adopting different OPC corrected data, so that the masks made by the masks meet the preset requirements. Specifically, as shown in FIG. 2B, the critical dimension of the line 32 in the second type feature pattern is 5nm larger than the critical dimension of the line in the second type inspection pattern on the reticle manufactured by the reticle foundry, i.e., the actual pattern on the manufactured reticle is 5nm smaller than the design pattern. When OPC is carried out to correct a chip graph (corresponding to a line in a second type detection graph) with the same characteristic information, the key dimension of the chip graph is enlarged by 5nm on the basis of the original OPC correction, so that the effect that the actual graph on the manufactured photomask is 5nm smaller than the designed graph can be exactly counteracted in the process of manufacturing the photomask. Further, a database of the fabrication capabilities of the reticles is established, the database including the fabrication capabilities of the reticles for a plurality of reticle factories. When a certain photomask factory is adopted to manufacture the photomask, the manufacturing capability of the photomask corresponding to the photomask factory is selected to form OPC data.

Further, the database also includes the capability of fabricating the different features fabricated by a single reticle foundry. As an example, as shown in fig. 2A, the critical dimension of the main line 30 in the first type feature pattern and the critical dimension of the main line in the first type inspection pattern on the reticle manufactured by the reticle foundry are different by 3 nm; as shown in fig. 2B, the critical dimension of the line 32 in the second type feature pattern is 5nm different from the critical dimension of the line in the second type inspection pattern on the reticle fabricated by the reticle foundry. The 3nm is different from 5nm, namely even though the photomask manufactured by the same photomask factory has different manufacturing capacities of different characteristic patterns, a database of the manufacturing capacities of the different characteristic patterns is manufactured, and OPC correction is performed on the manufacturing capacities of the different characteristic patterns, so that the pattern patterns manufactured on the photomask after correction are more accurate.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for correcting optical proximity effect, comprising:

providing at least one group of characteristic graph data, wherein the characteristic graph data corresponds to a characteristic graph;

manufacturing a detection pattern on the photomask according to the characteristic pattern data;

comparing the detection pattern with the characteristic pattern, and obtaining the manufacturing capability of the photomask according to the comparison result;

and forming OPC data according to the manufacturing capability of the photomask, and correcting the chip graph formed on the photomask according to the OPC data.

2. The method for correcting optical proximity effect according to claim 1, wherein the feature pattern has the same feature information as a chip pattern to be formed on the mask.

3. The method of claim 2, wherein the feature information includes at least a critical dimension of the pattern, a pitch of the pattern, and a gap of the pattern.

4. The method for correcting optical proximity effect according to claim 1, wherein the feature pattern is an OPC-corrected pattern or a non-OPC-corrected pattern.

5. The method according to claim 1, wherein the detection pattern is formed in a non-exposed region of the reticle.

6. The method for correcting optical proximity effect according to claim 5, wherein the mask comprises a chip region and a scribe line region surrounding the chip region, and the non-exposure region is located at a periphery of the scribe line region of the mask.

7. The method of claim 6, wherein the pattern of the chip region, the pattern of the scribe line region, and the pattern of the non-exposure region of the mask are formed in the same process, and the pattern of the non-exposure region includes the detection pattern.

8. The method for correcting optical proximity effect according to claim 1, further comprising:

establishing a database of the fabrication capabilities of the reticles, the database comprising the fabrication capabilities of the reticles for a plurality of reticle plants;

when a certain photomask factory is adopted to manufacture the photomask, the manufacturing capability of the photomask corresponding to the photomask factory is selected to form OPC data.

9. The method for correcting optical proximity effect according to claim 8, further comprising:

the database also includes the fabrication capabilities of the different features fabricated by a single reticle fab.

10. The method for correcting optical proximity effect according to claim 1, further comprising:

the mask has a fabrication capability including a difference size or a difference area between the feature pattern and the inspection pattern.