A method for OPC processing of metal layer pattern (MRC) restricted

Abstract

The application relates to the technical field of semiconductor integrated circuit manufacturing, and particularly discloses an OPC processing method for solving the MRC limitation of metal layer patterns, which comprises the following steps: S1, screening out metal layer line ends with hole layers as to-be-optimized line ends from a metal layer layout; S2, identifying 'L' type line ends from the to-be-optimized line ends, and the patterns opposite to the 'L' type line ends are 'I' type line ends; S3, screening out short side 'L' type line ends from the 'L' type line ends, and the length of the short side of the short side 'L' type line end is less than 0.5 times of a design standard of a hole to a target; and S4, identifying adjacent sides of the short side, and generating line end marks according to the adjacent sides. The OPC processing method for solving the MRC limitation of metal layer patterns can ensure that the 'I' type line ends obtain sufficient compensation by preferentially controlling and setting edge placement errors of the contours to the connected adjacent sides, and solves the problem of contour retreat of the 'I' type line ends.

Description

Technical Field

[0001] This invention relates to the field of semiconductor integrated circuit manufacturing technology, specifically to an OPC processing method for solving the limitation of MRC in metal layer patterns. Background Technology

[0002] In advanced semiconductor manufacturing processes, metal layers are used to connect hole layers (including contact holes, vias, etc.) between upper and lower layers. There are two typical types of line ends in metal layers: "L"-shaped line ends and "I"-shaped line ends. During OPC correction, line ends are typically corrected to a hammerhead shape, resulting in an outward-convex appearance on the mask.

[0003] like Figure 4 As shown, when the short side of the "L"-shaped line is short, the lithographic contour at its concave corner will protrude beyond the target pattern. In this case, the metal layer has excellent coverage, fully covering the underlying via layer. However, when the short side of the "L"-shaped line is directly opposite a "I"-shaped line, the OPC correction priority of the "I"-shaped line should be higher than that of the "L"-shaped line; otherwise, the "I"-shaped line will experience contour regression due to limitations imposed by mask rule checking (MRC).

[0004] Existing technologies (such as CN118011726A) propose a segmented compensation method, which performs step-by-step compensation by dividing the line end into adjacent segments and non-adjacent segments. However, this method is not optimized for special scenarios where the metal layer has a hole layer, nor does it consider the constraint of dense patterns around the line end on OPC correction, and it does not solve the contour retreat problem caused by MRC limitation of "I"-shaped line ends.

[0005] Therefore, there is an urgent need for an OPC correction method for the ends of metal layer holes, which can ensure the coverage margin of the hole layer, meet the spacing constraints of dense patterns, and effectively solve the problem of contour retreat of the "I"-shaped line ends. Summary of the Invention

[0006] The purpose of this invention is to provide an OPC processing method that solves the problem of limited MRC in metal layer patterns, thereby addressing the constraints on OPC correction caused by dense patterns around line ends when the metal layer has a hole layer, as well as the problem of contour retreat caused by limited MRC at the ends of "I"-shaped lines, as mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an OPC processing method for solving the limitation of MRC in metal layer patterns, comprising the following steps: S1, selecting metal layer line ends with holes from the metal layer layout as line ends to be optimized; S2, identifying "L"-shaped line ends from the line ends to be optimized, wherein the pattern directly opposite the "L"-shaped line end is a "I"-shaped line end; S3, selecting short-side "L"-shaped line ends from the "L"-shaped line ends, wherein the length of the short side of the short-side "L"-shaped line end is less than 0.5 times the design standard of the hole to the target; S4, identifying the adjacent side of the short side and generating line end marks based on the adjacent side; S5, performing OPC correction: first performing OPC correction on the "I"-shaped line ends, then performing OPC correction on the "L"-shaped line ends, and during the OPC correction, limiting the movement of the mask pattern within the range of the line end marks.

[0008] The allowable range for the edge placement error of the set contour to the adjacent side is 0.3 times the design standard of the hole to the target, to prevent insufficient mask movement from causing the hole layer to be exposed.

[0009] The "movement amount limit" in step S5 includes: limiting the outward convex movement of the mask within the range of the online end mark, so that the mask outline does not exceed the target graphic boundary exceeding a preset threshold.

[0010] The length of the line end mark in step S4 is the same as the length of the adjacent side.

[0011] The width of the line end mark is 0.5 times the design standard of the hole to the target.

[0012] The method is applicable to scenarios where there are dense patterns around the line ends, where dense patterns refer to graphic environments where the line end spacing is less than twice the design standard.

[0013] The hole layer includes a contact hole layer or a through hole layer, and the metal layer is an interconnect metal layer in the subsequent process.

[0014] The allowable range for edge placement error is the maximum permissible deviation from the outline edge to the edge of the adjacent metal graphic.

[0015] The shorter side is the side with the smaller size at the concave corner of the "L"-shaped line end.

[0016] The adjacent side of the short side is the side of the "L"-shaped line end that is directly opposite the "I"-shaped line end.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention achieves the following technical effects through hole layer identification, movement amount limitation and priority strategy: through priority control and setting the edge placement error from the contour to the connected adjacent edge, the present invention ensures that the "I"-shaped line end obtains sufficient compensation, and solves the problem of contour receding of the "I"-shaped line end; by setting the allowable range of edge placement error from the contour to the connected adjacent edge as 0.3 times the design standard from the hole to the target, it ensures that the hole layer is fully covered by the metal layer and prevents the hole layer from leaking; by limiting the movement amount of the line end mark, it ensures the spacing margin of dense patterns around the line end, meets the dense pattern constraint, realizes line end optimization without violating the mask rules, and is compatible with MRC rules. Description of Drawings

[0018] Figure 1 is a schematic flow chart of the method of the present invention; Figure 2 is a schematic diagram of an "L"-shaped line according to an embodiment of the present invention; Figure 3 is a schematic diagram of an "I"-shaped line end according to an embodiment of the present invention; Figure 4 is a schematic diagram of a restricted processing situation of a metal layer pattern in the prior art; Figure 5 is a schematic diagram of a processed metal layer pattern according to an embodiment of the method of the present invention.

[0019] In the figures: 1. metal layer; 2. hole layer; 3. metal layer contour; 4. mask pattern boundary; 5. short side; 6. concave corner. Detailed Description of the Embodiments

[0020] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined object of the invention, the specific implementation manners, structures, features and effects of the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments.

[0021] An OPC processing method for solving MRC limitation of metal layer patterns according to embodiments of the present invention is described below with reference to the accompanying drawings.

[0022] As Figure 1 shown, the OPC processing method for solving MRC limitation of metal layer patterns according to one embodiment of the present invention includes the following steps: Step S1: screening out, from the layout of metal layer 1, the line ends of metal layer 1 with hole layer 2 as line ends to be optimized; In metal layer 1 corresponding to the layout, check whether there is hole layer 2 (contact hole or via hole) at each line end. Line ends with hole layer 2 are screened out as line ends to be optimized.

[0023] Step S2: identifying "L"-shaped line ends from the line ends to be optimized, and the pattern facing the "L"-shaped line end is an "I"-shaped line end; The line ends are classified according to their geometric shape. The "L"-shaped line ends have perpendicularly intersecting long and short sides, while the "I"-shaped line ends are isolated line ends.

[0024] Step S3: Select the short-side "L"-shaped wire ends from the "L"-shaped wire ends. The length of the short side of the short-side "L"-shaped wire end is less than 0.5 times the design standard of the hole to the target. Measure the length of the short side 5 of the "L"-shaped line end. When the length of the short side 5 is less than 0.5×DR (DR is the design rule value for hole to target, i.e., the distance from the center of the hole to the target position of the metal line end), it is determined to be a "L"-shaped line end with short side 5. The concave angle 6 of the "L"-shaped line end with short side 5 will produce an outward convex profile during photolithography, so that the metal layer 1 has good wrapping properties for the hole layer 2.

[0025] Step S4: Identify the adjacent edges of the short side and generate line end marks based on these adjacent edges. Identify the connected adjacent edges of the short side 5 "L" shaped line end. When the metal layer 1 opposite the connected adjacent edge has a hole layer 2, generate line end marks based on these connected adjacent edges. For example... Figure 5 As shown, a line end marker is generated based on the adjacent edge of the short side 5 "L" shaped line end. The length of the line end marker is the same as the length of the adjacent edge, and the width is 0.5 × DR. The line end marker defines the virtual constraint area for OPC correction. In step S4, the length of the line end marker is the same as the length of the adjacent edge, and the width is 0.5 times the design standard from the hole to the target.

[0026] Step S5: Perform OPC correction: First, perform OPC correction on the "I" shaped line end, and then perform OPC correction on the "L" shaped line end. During the OPC correction, the movement of the mask pattern located within the line end marking range is limited. Identify the adjacent edge of the short side 5 "L" shaped wire end, and check whether there is an "I" shaped wire end and its hole in the metal layer 1 area directly opposite that adjacent edge. For example... Figure 5 As shown, when the short side 5 "L" shaped line end is directly opposite a "I" shaped line end, a correction priority needs to be established. OPC correction of the "I" shaped line end is performed first to ensure its outline does not shrink; then OPC correction of the "L" shaped line end is performed, utilizing its natural wrapping advantage. Finally, the mask pattern 4 is output to fabricate the photomask. The priority strategy in step S6 is based on the following optical proximity effect characteristics: the outline at the concave corner 6 of the short side 5 "L" shaped line end will bulge outwards from the target, giving the metal layer 1 a wrapping advantage; therefore, the "I" shaped line end needs priority compensation to avoid outline shrinkage.

[0027] The "movement amount limit" in step S5 includes: limiting the outward convex movement of the mask 4 within the range of the line end mark, so that the contour of the mask 4 does not exceed the boundary of the target graphic and exceeds a preset threshold. The movement of the mask 4 within the marked area is limited. The outward protrusion of the mask 4 is limited to ensure that it does not exceed the target boundary excessively, thus ensuring that the spacing between it and the surrounding dense patterns meets safety requirements.

[0028] Example 2 An OPC processing method for solving the limitation of MRC in the pattern of metal layer 1 further includes: step S7, setting the edge placement error of the contour to the adjacent side; The allowable error range for the placement of the contour to the adjacent edge is set to 0.3 times the design standard for the hole to the target, to prevent insufficient movement of the mask 4 from causing leakage of the hole layer 2. For example... Figure 5 As shown, the contour after adopting the method of the present invention has a lower line end position and more sufficient compensation compared with the contour of the prior art. The allowable range of edge placement error is the maximum allowable deviation from the edge of the contour to the edge of the adjacent metal pattern, and the value of 0.3 times the design standard ensures the spacing margin of the dense pattern around the line end.

[0029] The method is applicable to scenarios where there are dense patterns around the line ends, where dense patterns refer to graphic environments where the line end spacing is less than twice the design standard. The hole layer 2 includes contact hole layer 2 or through-hole layer 2, and the metal layer 1 is the interconnect metal layer 1 used in the subsequent process. After completing the OPC correction, a photomask is fabricated based on the final mask pattern 4, and a photolithography exposure process is performed.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. An OPC processing method for solving the limitation of MRC in metal layer patterns, characterized in that, Includes the following steps: S1. Select the metal layer line ends with holes from the metal layer layout as the line ends to be optimized. S2. Identify the "L"-shaped line end from the line ends to be optimized, and the graphic opposite the "L"-shaped line end is the "I"-shaped line end; S3. Select the short-side "L"-shaped line ends from the "L"-shaped line ends, wherein the length of the short side of the short-side "L"-shaped line end is less than 0.5 times the design standard of the hole to the target. S4. Identify the adjacent edges of the short edge and generate line end marks based on the adjacent edges; S5. Perform OPC correction: First, perform OPC correction on the "I"-shaped line ends, then perform OPC correction on the "L"-shaped line ends. During the OPC correction, the movement of the mask pattern within the marked area of ​​the line ends is limited.

2. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 1, characterized in that: The allowable range for the edge placement error of the set contour to the adjacent side is 0.3 times the design standard of the hole to the target, to prevent insufficient mask movement from causing the hole layer to be exposed.

3. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 2, characterized in that: The "movement amount restriction" in step S5 includes: limiting the outward convex movement of the mask within the range of the online end mark, so that the mask outline does not exceed a preset threshold of the target graphic boundary.

4. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 1, characterized in that: The length of the line end mark in step S4 is the same as the length of the adjacent side.

5. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 4, characterized in that: The width of the line end mark is 0.5 times the design standard of the hole to the target.

6. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 1, characterized in that: The method is applicable to scenarios where there are dense patterns around the line ends, where dense patterns refer to graphic environments where the line end spacing is less than twice the design standard.

7. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 1, characterized in that: The hole layer includes a contact hole layer or a through hole layer, and the metal layer is an interconnect metal layer in the subsequent process.

8. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 2, characterized in that: The allowable range for edge placement error is the maximum permissible deviation from the outline edge to the edge of the adjacent metal graphic.

9. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 1, characterized in that: The shorter side is the side with the smaller size at the concave corner of the "L"-shaped line end.

10. The OPC processing method for solving the limitation of MRC in metal layer patterns according to claim 9, characterized in that: The adjacent side of the short side is the side of the "L"-shaped line end that is directly opposite the "I"-shaped line end.

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