A metal interconnection mask structure for manufacturing metal interconnection lines across photolithography fields

Abstract

The present invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a metal interconnection mask structure for manufacturing cross-lithography field metal interconnects. The structure comprises: a secondary exposure area, the secondary exposure areas being distributed on the upper, lower, left, and right sides of a single mask; the metal interconnection mask structure being located within the secondary exposure area and being used to form cross-lithography field metal interconnects between two adjacent lithography fields; and a portion of each metal interconnection mask having a larger area than the area corresponding to the target metal interconnect shape, while the remaining portion of the area has the target metal interconnect shape. The present invention eliminates the problem of deterioration of the cross-lithography field metal interconnect morphology and reduced interconnect quality caused by secondary exposure.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a metal interconnection mask structure for manufacturing metal interconnection lines across photolithography fields. Background Art

[0002] The current semiconductor integrated circuit technology is generally developing in two directions: first, the process technology continues to evolve in accordance with the miniaturization iteration of Moore's Law, reducing the process feature size, improving the transistor density, and increasing the total number of transistors; second, through various technological innovations, breaking through the lithography field size limitations, expanding the chip area, and increasing the total number of transistors.

[0003] In traditional photolithography, there is no overlap between adjacent photolithography fields, and a certain distance is reserved between the photolithography fields as scribe grooves; the stepper lithography machine exposes the photolithography fields one by one in sequence, and each photolithography field is exposed only once; finally, a single chip is produced by scribe.

[0004] Wafer-Scale Integration (WSI) technology breaks down the physical isolation between lithography fields by cross-linking masks. It then utilizes metal interconnects across lithography fields to enable data transmission between adjacent lithography fields. Unlike traditional photolithography, WSI technology eliminates the need for dicing; the entire wafer is a single chip. This technology is expected to become a key solution for achieving large-area chip fabrication in the post-Moore era.

[0005] During the wafer-level integration process, the sides of each lithography field are repeatedly exposed twice during stepping, known as the double exposure zone. The four corners of each lithography field are repeatedly exposed four times, known as the quadruple exposure zone. The lithography pattern of the metal interconnects across the lithography field within the double exposure zone is damaged by the increased number of exposures, which in turn affects the subsequent metal etching process, ultimately deteriorating the metal interconnect morphology and reducing interconnect quality.

[0006] Therefore, it is an important topic to study the mask structure of metal interconnects across lithography fields in wafer-level integration processes, minimize the adverse effects of secondary exposure on the lithography and etching processes of metal interconnects, and improve the reliability of metal interconnects. It is of great significance to the development of wafer-level integration processes. Summary of the Invention

[0007] The purpose of the present invention is to provide a metal interconnection mask structure and mask for manufacturing cross-lithography field metal interconnection lines, so as to solve the problem of deterioration of cross-lithography field metal interconnection line morphology and reduction of interconnection quality caused by secondary exposure in wafer-level integration process.

[0008] In order to solve the above technical problems, the present invention provides a metal interconnection mask structure for manufacturing cross-photolithography field metal interconnection lines, including a secondary exposure area, which is distributed on the upper side, lower side, left side and right side of a single mask; the metal interconnection mask structure is located in the secondary exposure area, and is used to form a cross-photolithography field metal interconnection line between two adjacent photolithography fields; and a part of the area of ​​each of the metal interconnection mask is larger than the area corresponding to the target metal interconnection line shape, and the shape of the remaining other part of the area is the target metal interconnection line shape.

[0009] Preferably, when the metal interconnection mask structure on the left or upper side is translated to overlap with the metal interconnection mask structure on the right or lower side, the intersecting shape is the target metal interconnection line shape, and the shape of the union completely includes the target metal interconnection line shape.

[0010] Preferably, the single mask plate includes: a single exposure area in the center area, secondary exposure areas at the upper side, lower side, left side and right side, and four exposure areas at the upper left corner, upper right corner, lower right corner and lower left corner.

[0011] Preferably, the cross-lithography field metal interconnection line is located in the secondary exposure area and has a certain geometric shape.

[0012] Preferably, the cross-lithography field metal interconnection line located in the secondary exposure area on the left and right sides has its left end edge in contact with the left edge of the secondary exposure area, and its right end edge in contact with the right edge of the secondary exposure area, so as to connect the two adjacent lithography fields on the left and right.

[0013] Preferably, the cross-photolithography field metal interconnection line located in the secondary exposure area on the upper and lower sides has its upper edge in contact with the upper edge of the secondary exposure area, and its lower edge in contact with the lower edge of the secondary exposure area, so as to connect the two adjacent upper and lower photolithography fields.

[0014] Preferably, the width of one end of the metal interconnection mask structure located inside or outside the single mask is the width of the target metal interconnection line shape, and the width of one end located outside or inside the single mask is larger than the width of the target metal interconnection line shape.

[0015] Preferably, the metal interconnection mask structures located in the secondary exposure areas on the left and right sides or the upper and lower sides have the same or different shapes, but are all arranged symmetrically.

[0016] Preferably, the metal interconnection mask structure consists of two rectangles with different widths or consists of a rectangle and a trapezoid.

[0017] The present invention also provides a mask, comprising the metal interconnection mask structure for manufacturing cross-lithography field metal interconnection lines as described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention makes a special design for the shape of the cross-photolithography field metal interconnection mask: first, the shape of some areas of each cross-photolithography field metal interconnection mask in the secondary exposure area is changed to a shape larger than the target shape, and the shape of other areas is the target shape; second, it is required that when the cross-photolithography field metal interconnection mask in the left secondary exposure area is translated to overlap with the cross-photolithography field metal interconnection mask in the right secondary exposure area, the intersecting shape is the target metal interconnection line shape, and the shape of the union completely includes the target metal interconnection line shape; when the cross-photolithography field metal interconnection mask in the upper secondary exposure area is translated to overlap with the cross-photolithography field metal interconnection mask in the lower secondary exposure area, the intersecting shape is the target metal interconnection line shape, and the shape of the union completely includes the target metal interconnection line shape. During the double exposure process, the side of the photoresist corresponding to each cross-lithography field metal interconnect line located in the secondary exposure area is only exposed once, eliminating the problem of deterioration of the cross-lithography field metal interconnect line morphology and reduced interconnection quality caused by secondary exposure, which is of great significance to the development of wafer-level integration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure distribution of a single mask.

[0021] Figure 2 This is a schematic diagram of the metal interconnect lines across the secondary exposure area of ​​a single lithography field.

[0022] Figure 3 It is a schematic diagram of two adjacent lithography fields on the left and right being interconnected by a cross-lithography field metal interconnection line.

[0023] Figure 4 It is a schematic diagram of the photoresist morphology after the exposure and development of two adjacent photolithography fields are completed by using a general cross-photolithography field metal interconnect mask structure for photolithography.

[0024] Figure 5 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 1 .

[0025] Figure 6 It is the use of Figure 5 Schematic diagram of photoresist after mask exposure and development are completed.

[0026] Figure 7 It is the use of Figure 5Schematic diagram of the secondary exposure area when the mask shown is used to expose the left photolithography field.

[0027] Figure 8 is completed Figure 7 After the first exposure, the lithography machine steps right once and continues to use Figure 5 Schematic diagram of the secondary exposure area when the mask shown is used to expose the right photolithography field.

[0028] Figure 9 It is a schematic diagram of the once-exposed position, the unexposed position, and the unexposed position in the secondary exposure area after the double exposure is completed.

[0029] Figure 10 The diagram is a schematic diagram of the photoresist morphology after photolithography exposure and development of two adjacent photolithography fields are completed by using the cross-photolithography field metal interconnection mask structure proposed by the present invention for photolithography.

[0030] Figure 11 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 2 .

[0031] Figure 12 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 3 .

[0032] Figure 13 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 4 .

[0033] Figure 14 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 5 .

[0034] Figure 15 This is a schematic diagram of a cross-lithography field metal interconnection mask structure proposed by the present invention. Figure 6 .

[0035] In the figure: 00: single exposure area; 01: double exposure area 1; 02: double exposure area 2; 03: double exposure area 3; 04: double exposure area 4; 05: quadruple exposure area 1; 06: quadruple exposure area 2; 07: quadruple exposure area 3; 08: quadruple exposure area 4; 09: metal interconnection line 1; 10: metal interconnection line 2; 11: metal interconnection line 3; 12: metal interconnection line 4; 13: metal interconnection area; 14: location where photoresist is removed using a general mask; 15: location where photoresist remains using a general mask; 16: location where photoresist is removed using a general mask Figure 5 The position of the remaining photoresist on the mask shown; 17: using Figure 5 The photoresist locations on the mask shown are exposed only once. Figure 5 The photoresist position of the mask shown is not exposed; 19: using Figure 5 The photoresist position exposed in the photolithography field on the right side of the mask shown; 20: using Figure 5 The unexposed photoresist position of the right lithography field of the mask shown; 21: using Figure 5 The photoresist position 2 of the mask shown is not exposed; 22: using Figure 5 The photoresist locations on the mask shown are exposed in both exposure operations. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0037] The cross-field metal interconnection mask of the present invention is used for positive photoresist lithography. Positive photoresist refers to a photoresist in which the areas not covered by the mask (the exposed areas) undergo a chemical reaction, dissolving in the developer. The photoresist areas covered by the mask are insoluble in the developer and are used to form the metal interconnection line shape after etching.

[0038] Figure 1 This is a schematic diagram of the structure distribution of a single mask. Figure 1 As shown, the internal area of ​​a single mask is the single exposure area 00, the upper side of the single exposure area 00 is the secondary exposure area 1 01, the right side is the secondary exposure area 2 02, the lower side is the secondary exposure area 3 03, and the left side is the secondary exposure area 4 04. The upper left corner of the single exposure area 00 is the fourth exposure area 1 05, the upper right corner is the fourth exposure area 2 06, the lower right corner is the fourth exposure area 3 07, and the lower left corner is the fourth exposure area 4 08.

[0039] Figure 2 Schematic diagram of metal interconnection lines across photolithography fields in the secondary exposure area of ​​a single photolithography field. Figure 2 As shown, the cross-photolithography field metal interconnects distributed in the four secondary exposure areas of secondary exposure area 1 01, secondary exposure area 2 02, secondary exposure area 3 03, and secondary exposure area 4 04 are metal interconnect 2 10, metal interconnect 3 11, metal interconnect 4 12, and metal interconnect 1 09 respectively.

[0040] Figure 3 Schematic diagram of two adjacent lithography fields interconnected by metal interconnection lines across lithography fields. Figure 3As shown in FIG, the left lithography field and the right lithography field overlap in the metal interconnection area 13 to form a secondary exposure area. The left lithography field and the right lithography field are interconnected through the cross-lithography field metal interconnection line in the secondary exposure area. Figure 3 Similarly, it is sufficient to arrange the two lithography fields in a vertical direction and overlap the secondary exposure areas on the upper and lower sides of the two lithography fields. This is not described here. The following examples use two adjacent lithography fields.

[0041] Figure 4 This is a schematic diagram of the photoresist morphology after the exposure and development of two adjacent photolithography fields using a general cross-photolithography field metal interconnection mask structure (in fact, it is also a schematic diagram of the cross-photolithography field metal interconnection structure obtained after exposure, development and etching). Figure 4 As shown, position 14 where the photoresist is removed using a general mask is the position where the photoresist is removed after exposure and development, and position 15 where the photoresist remains using a general mask is the position where the photoresist remains after exposure and development.

[0042] The so-called general cross-photolithography field metal interconnection mask structure means that the cross-photolithography field metal interconnection structure in the left secondary exposure area is exactly the same as the cross-photolithography field metal interconnection structure in the right secondary exposure area, and both are target metal interconnection line shapes.

[0043] exist Figure 4 In the example, the positions of the two exposures in the secondary exposure area completely overlap, resulting in repeated exposure twice of position 14 where the photoresist was removed using a general mask. This can easily cause the edge of the photoresist at position 15 where the photoresist remains using a general mask to shrink within the secondary exposure area, ultimately resulting in a smaller line width and larger spacing of the metal interconnect lines across the lithography field, affecting the interconnection effect.

[0044] Figure 5 This is a schematic diagram of a metal interconnection mask structure across photolithography fields provided by the present invention. Figure 5 In the example, the width of the end of the metal interconnection mask across the lithography field located inside the entire mask is the target width, and the width of the end located outside the entire mask is larger than the target width. However, this is only one example and is not a limiting condition. As long as the shape of the mask in the left secondary exposure area is opposite to the shape of the mask in the right secondary exposure area, and the shape of the mask in the upper secondary exposure area is opposite to the shape of the mask in the lower secondary exposure area, it is covered within the scope of the present invention. Figures 11 to 13 As shown; Figure 5 、 Figure 11 、 Figure 12 、 Figure 13These are schematic diagrams of four different cross-lithography field metal interconnection mask structures proposed by the present invention. In these four figures, the shapes of the mask patterns in the secondary exposure area are the same, but the placement directions are different.

[0045] exist Figure 5 In the example, the cross-lithography field metal interconnection mask is composed of two rectangles with different widths. However, this is only one example and is not a limiting condition. The present invention only requires that the shape of certain areas of the cross-lithography field metal interconnection mask in the secondary exposure area is the target shape, and the shape of other areas is larger than the target shape. For example, the shape of one end of the cross-lithography field metal interconnection mask in the secondary exposure area can be a trapezoid larger than the target shape, such as Figure 14 As shown, Figure 5 The shape of each metal interconnect line across the lithography field consists of two rectangles, and Figure 14 The shape of each metal interconnect line across the lithography field consists of a rectangle and a trapezoid.

[0046] exist Figure 5 In the example, the left and right secondary exposure areas of the cross-lithography field metal interconnection mask have the same shape but are in opposite directions; the upper and lower secondary exposure areas of the cross-lithography field metal interconnection mask have the same shape but are in opposite directions. However, this is only one example and is not a limiting condition. The present invention has no special requirements for the specific shape of the cross-lithography field metal interconnection mask. For example, Figure 15 The shape of each cross-lithography field metal interconnection line in the left secondary exposure area is different from the shape of each cross-lithography field metal interconnection line in the right secondary exposure area. The shape of each cross-lithography field metal interconnection line in the upper secondary exposure area is different from the shape of each cross-lithography field metal interconnection line in the lower secondary exposure area. That is, the cross-lithography field metal interconnection line mask in the left secondary exposure area is composed of two rectangles with different widths, and the cross-lithography field metal interconnection line mask in the right secondary exposure area is composed of a rectangle and a trapezoid, as shown in FIG. Figure 15 shown.

[0047] In summary, the present invention only requires that the intersection of the cross-field metal interconnection reticle in the left secondary exposure area and the cross-field metal interconnection reticle in the right secondary exposure area be the target metal interconnection shape, and that the shape of their union completely encompass the target metal interconnection shape. There are no specific requirements for the shape of each cross-field metal interconnection. The same applies to the cross-field metal interconnection reticle in the upper secondary exposure area and the cross-field metal interconnection reticle in the lower secondary exposure area.

[0048] Figure 6 It is the use of Figure 5 The photoresist diagram shown in the figure is after the mask is exposed and developed. Figure 6 As shown, using Figure 5The position 16 of the remaining photoresist on the mask is the position of the remaining photoresist after the secondary exposure and development. Figure 5 The photoresist position 17 of the mask shown is exposed only once, which is the photoresist position exposed only once in the double exposure operation. Figure 7 and Figure 8 .

[0049] Figure 7 It is the use of Figure 5 The schematic diagram of the secondary exposure area when the mask is exposed to the left lithography field. Figure 7 As shown, using Figure 5 The photoresist position 18 of the mask shown is not exposed and is used Figure 5 The photoresist position 19 exposed in the photolithography field on the right side of the mask is the photoresist position blocked by the mask. Figure 5 The unexposed photoresist position 18 of the mask is shown and the Figure 5 The other areas of the right side of the mask are exposed except for the exposed photoresist position 19 of the photolithography field.

[0050] Figure 8 is completing Figure 7 After the first exposure, the lithography machine steps right once and continues to use Figure 5 The schematic diagram of the secondary exposure area when the mask is exposed to the right lithography field. Figure 8 As shown, using Figure 5 The unexposed photoresist position 20 of the right lithography field of the mask is shown and the Figure 5 The photoresist position 21 of the mask that is not exposed is the photoresist position blocked by the mask. Figure 5 The unexposed photoresist position 20 of the right lithography field of the mask is shown and the Figure 5 The remaining areas of the mask other than the unexposed photoresist position 21 are exposed.

[0051] Figure 7 Use in Figure 5 The unexposed photoresist position 18 of the mask is shown. Figure 8 Use in Figure 5 The unexposed photoresist position 21 of the mask is the same position, that is, the target position of the metal interconnection line across the photolithography field. Figure 7 and Figure 8 As shown, using Figure 5 The photoresist position 18 of the mask that is not exposed (i.e., using Figure 5 The photoresist at the unexposed photoresist position 21 of the mask shown is blocked by the mask during both exposure processes.

[0052] Figure 7 Use in Figure 5 The photoresist position 19 and the exposed photoresist position 19 of the right side of the mask are shown. Figure 8 Use in Figure 5 The unexposed photoresist position 20 in the right lithography field of the mask is the target position of the metal interconnection line across the lithography field (using Figure 5 The photoresist position of the mask shown is not exposed. Figure 5 The side of the mask shown has unexposed photoresist position 21).

[0053] Combine Figure 7 and Figure 8 Analysis, from Figure 7 As can be seen, Figure 8 Use in Figure 5 The unexposed photoresist position 20 in the right lithography field of the mask is shown. Figure 7 The first exposure was not blocked; Figure 8 As can be seen, using Figure 5 The unexposed photoresist position 20 of the right side of the mask is blocked by the mask during the second exposure process. Figure 5 The unexposed photoresist position 20 in the right-hand photolithography field of the mask is actually exposed only once.

[0054] Combine Figure 7 and Figure 8 Analysis, from Figure 8 As can be seen, Figure 7 Use in Figure 5 The photoresist position 19 exposed in the photolithography field on the right side of the mask is Figure 8 The second exposure process was not blocked; Figure 7 As can be seen, using Figure 5 The photoresist position 19 exposed in the right lithography field of the mask is blocked by the mask during the first exposure process. Figure 5 The exposed photoresist position 19 of the right-hand photolithography field of the reticle is actually exposed only once.

[0055] In general, if Figure 9 As shown, in the double exposure process, the utilization of the secondary exposure area Figure 5 The photoresist position 19 of the right side of the mask is exposed and the photoresist position 19 ... Figure 5 The unexposed photoresist position 20 in the right lithography field of the mask is actually exposed only once; Figure 9 As shown, in the double exposure process, the utilization of the secondary exposure area Figure 5 The photoresist position 18 of the mask that is not exposed (i.e., using Figure 5The photoresist positions 21) not exposed by the mask are all blocked by the mask and are not actually exposed; Figure 9 As shown, in the double exposure process, the secondary exposure area is used in addition to the Figure 5 The photoresist position 18 of the mask that is not exposed (i.e., using Figure 5 The photoresist position of the mask shown is not exposed 21) using Figure 5 The photoresist position 19 of the right side of the mask is exposed and the photoresist position 19 ... Figure 5 The other positions other than the unexposed photoresist position 20 of the right lithography field of the mask (i.e., the positions of the unexposed photoresist position 20) are shown. Figure 5 The photoresist position 22 that is exposed in both exposure operations of the mask is not blocked by the mask both times and is actually exposed twice.

[0056] After two exposure processes, whether it is only exposed once, Figure 5 The photoresist position 19 of the right side of the mask is exposed and the photoresist position 19 ... Figure 5 The photoresist at the photoresist position 20 on the right side of the mask is not exposed, but is exposed twice. Figure 5 The photoresist at the photoresist position 22 that is exposed in both exposure operations of the mask shown will be removed after development, and only the photoresist at the photoresist position 22 will be removed. Figure 5 The photoresist position 18 of the mask that is not exposed (i.e., using Figure 5 The photoresist remains at the unexposed photoresist position 21 of the mask, as shown in FIG. Figure 12 shown.

[0057] Theoretically, the cross-lithography field metal interconnection structure obtained after exposure, development and etching (such as Figure 10 shown) with Figure 4 There is no difference.

[0058] But in the actual double exposure process, Figure 4 In the conventional mask, the photoresist of each metal interconnect line crossing the photolithography field at the position 15 of the remaining photoresist is exposed twice on both sides in the secondary exposure area. The quality of the photoresist is inevitably affected by the double exposure and degraded.

[0059] During the two exposures, Figure 10 Utilization Figure 5 The photoresist position 18 of the mask that is not exposed (i.e., using Figure 5 The two sides of each metal interconnect line across the photolithography field in the unexposed photoresist position 21 of the mask shown are exposed only once in the secondary exposure area, eliminating the problem of metal interconnect line morphology deterioration and interconnection quality reduction caused by secondary exposure.

[0060] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A metal interconnection mask structure for manufacturing a metal interconnection line across a photolithography field, characterized in that: The invention comprises secondary exposure areas, which are distributed on the upper, lower, left and right sides of a single mask. The metal interconnection mask structure is located in the secondary exposure area and is used to form a cross-photolithography field metal interconnection line between two adjacent photolithography fields. Part of the area of ​​each metal interconnection mask is larger than the area corresponding to the target metal interconnection line shape, and the shape of the remaining part of the area is the target metal interconnection line shape. When the re-exposure area cross-lithography field metal interconnection mask is translated and overlapped, the intersection shape is the target metal interconnection line shape, and the union shape completely contains the target metal interconnection line shape. During the two exposure processes, the side of the photoresist corresponding to each cross-lithography field metal interconnection line located in the re-exposure area is only exposed once; The cross-lithography field metal interconnection line is located in the secondary exposure area and has a geometric shape; The cross-lithography field metal interconnection line located in the left and right secondary exposure areas has its left end edge in contact with the left edge of the secondary exposure area and its right end edge in contact with the right edge of the secondary exposure area, so as to connect the two adjacent lithography fields on the left and right; The cross-photolithography field metal interconnection line located in the secondary exposure area on the upper and lower sides has its upper edge in contact with the upper edge of the secondary exposure area, and its lower edge in contact with the lower edge of the secondary exposure area, so as to connect the two adjacent photolithography fields above and below.

2. A metal interconnection mask structure for manufacturing cross-lithography field metal interconnection lines according to claim 1, characterized in that: When the metal interconnection mask structure on the left or upper side is translated to overlap with the metal interconnection mask structure on the right or lower side, the intersecting shape is the target metal interconnection line shape, and the shape of the union completely includes the target metal interconnection line shape.

3. The metal interconnection mask structure for manufacturing cross-lithography field metal interconnection lines according to claim 1, characterized in that: The single mask plate includes: a single exposure area in the center area, secondary exposure areas at the upper side, lower side, left side and right side, and four exposure areas at the upper left corner, upper right corner, lower right corner and lower left corner.

4. The metal interconnection mask structure for manufacturing cross-lithography field metal interconnection lines according to claim 1, characterized in that: The metal interconnection mask structures located in the secondary exposure areas on the left and right sides or the upper and lower sides have the same or different shapes, but are all arranged symmetrically.

5. The metal interconnection mask structure for manufacturing cross-lithography field metal interconnection lines according to claim 4, characterized in that: The metal interconnection mask structure is composed of two rectangles with different widths or a rectangle and a trapezoid.

6. A mask, characterized in that: The invention comprises a metal interconnection mask structure for manufacturing a cross-lithography field metal interconnection line according to any one of claims 1 to 5.

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