CN216958032U - Semiconductor structure - Google Patents

Abstract

A semiconductor structure includes a plurality of active patterns arranged in an array and a surrounding pattern surrounding the plurality of active patterns. At least one branch pattern is attached to the inside edge of the surrounding pattern. The branch patterns and the active patterns have the same extension direction, and the ends of the surrounding patterns are aligned with the ends of the adjacent active patterns. The branch pattern can make the pattern density between the active pattern array and the surrounding pattern more uniform, and help the insulating layer more easily and completely fill the gap between the active pattern and the surrounding pattern.

Description

Semiconductor structure

Technical Field

The present invention relates to a semiconductor structure, and more particularly, to a semiconductor structure including an array pattern and a surrounding pattern.

Background

A Dynamic Random Access Memory (DRAM) is a volatile memory, and includes an array area (array area) formed by a plurality of memory cells (memory cells) and a peripheral area (peripheral area) formed by a control circuit. Each memory cell is composed of a transistor (transistor) and a capacitor (capacitor) electrically connected with the transistor, and the transistor controls the storage or release of charges in the capacitor to achieve the purpose of storing data. The control circuit is addressable to each memory cell by Word Lines (WL) and Bit Lines (BL) extending across the array region and electrically connected to each memory cell to control access to data from each memory cell.

Currently, the fabrication of dram includes defining a plurality of active areas on a semiconductor substrate, and then fabricating memory cells based on the active areas. How to fabricate more densely arranged active regions on a substrate to obtain a higher integration density of dram chips is a subject of continuous research in the field.

SUMMERY OF THE UTILITY MODEL

The present invention provides a semiconductor structure and a method for fabricating the same, which can obtain a tightly arranged active pattern array and a surrounding pattern surrounding the active pattern array by cutting a plurality of stripe patterns through a plurality of parallel arranged trenches. The surrounding pattern may provide structural support and stress buffering around the active pattern array. In addition, the branch pattern connected to the edge of the peripheral pattern can make the periphery of the active pattern array have more uniform pattern density, and the first insulating layer can more easily and completely fill the gap between the active pattern and the peripheral pattern.

According to an embodiment of the utility model, the semiconductor structure comprises a substrate, and a plurality of active patterns are arranged in the substrate, extend along a first direction respectively, and are aligned along the first direction and a second direction. A surrounding pattern is disposed in the substrate and surrounds the plurality of active patterns. At least one branch pattern connected to an inner edge of the surrounding pattern and extending along the first direction, wherein ends of the branch pattern are aligned with ends of an adjacent active pattern along the second direction.

A method of fabricating a semiconductor structure according to an embodiment of the present invention includes the following steps. First, a first pattern layer is formed on a substrate, wherein the first pattern layer includes a plurality of stripe patterns arranged in parallel and respectively extending along a first direction, and a peripheral pattern surrounding the stripe patterns. And forming a second pattern layer on the first pattern layer, wherein the second pattern layer comprises a plurality of groove patterns which are arranged in parallel and respectively extend along a second direction. Then, the plurality of bar patterns are etched through the plurality of trench patterns to cut the plurality of bar patterns into a plurality of active patterns and at least one branch pattern connected to an inner side edge of the surrounding pattern. The end of the branch pattern is aligned with the end of an adjacent active pattern along the second direction.

Drawings

Fig. 1-4 are schematic plan views illustrating various steps in a semiconductor structure during a manufacturing process according to an embodiment of the utility model.

Fig. 5 and 6 illustrate a variation of the steps shown in fig. 3 and 4.

Fig. 7 and 8 illustrate another variation of the steps shown in fig. 3 and 4.

FIGS. 9-11 are schematic plan views illustrating different steps in the fabrication process of a semiconductor structure according to another embodiment of the present invention.

Fig. 12 illustrates a variation of the semiconductor structure shown in fig. 11.

Fig. 13 illustrates another variation of the semiconductor structure shown in fig. 11.

Wherein the reference numerals are as follows:

d1 first direction

D2 second direction

10 first pattern layer

12 stripe pattern

14 surrounding pattern

14' surrounding block pattern

14a inner edge

14b cut part

14c arc groove

14e outer edge of

16 active pattern

16a end part

18 branch pattern

18a end part

20 second pattern layer

22 groove pattern

100 substrate

101 first pattern layer

102 stripe pattern

114 surrounding pattern

114' surrounding block pattern

114a inner edge

114b cut-out portion

114e outside edge

116 active pattern

116a end portion

118 branching pattern

118a end

120 isolation structure

122 first insulating layer

124 second insulating layer

126 third insulating layer

128 fourth insulating layer

CT1 groove

CT2 arc groove

CT3 groove

CT4 arc groove

LD1 extension line

LD2 extension line

SP isolation trench

Detailed Description

In order to make the present invention more comprehensible to those skilled in the art, preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. It is to be understood that the embodiments described below may be implemented in various other forms of implementation, which may be substituted, recombined, or mixed with other features of various embodiments without departing from the spirit of the present invention.

Referring to fig. 1 to 4, schematic plan views of a semiconductor structure according to an embodiment of the utility model at different steps of a manufacturing process are shown. A method of fabricating a semiconductor structure may include the following steps. As shown in fig. 1, a substrate 100 is provided, and a first pattern layer 10 is formed on the substrate 100. The substrate 100 is, for example, a silicon (Si) substrate, an epitaxial silicon (epitaxial silicon) substrate, a silicon germanium (SiGe) substrate, a silicon carbide (SiC) substrate, or a silicon-on-insulator (SOI) substrate, but is not limited thereto. The material of the first pattern layer 10 may include a photoresist or a dielectric material such as silicon oxide, silicon nitride, or silicon oxynitride, but is not limited thereto. According to an embodiment of the present invention, the first pattern layer 10 may include silicon nitride. The first pattern layer 10 includes a plurality of bar patterns 12 extending along the first direction D1 and arranged in parallel, and a surrounding pattern 14 surrounding the bar patterns 12. Both ends of the bar pattern 12 are attached to the inner side edge 14a of the surrounding pattern 14.

As shown in fig. 2, a second pattern layer 20 is formed to cover the substrate 100 and the first pattern layer 10 globally, and then a patterning process (e.g., a photolithography and etching process) is performed on the second pattern layer 20 to form a plurality of trench patterns 22 extending along the second direction D2 and arranged in parallel in the second pattern layer 20, exposing portions of the bar patterns 12 and the surrounding patterns 14. The material of the second pattern layer 20 may include a photoresist or a dielectric material such as silicon oxide, silicon nitride, or silicon oxynitride, but is not limited thereto. The material of the second patterning layer 20 is different from that of the first patterning layer 10. According to an embodiment of the present invention, the second patterning layer 20 may include a photoresist. The first direction D1 and the second direction D2 are different directions, and an included angle therebetween can be adjusted according to design requirements. According to an embodiment of the present invention, the included angle between the first direction D1 and the second direction D2 may be between 15 degrees and 130 degrees, but is not limited thereto.

As shown in fig. 3, the first pattern layer 10 is then etched using the second pattern layer 20 as a mask to remove portions of the bar patterns 12 and the peripheral patterns 14 exposed from the trench patterns 22, so as to cut the bar patterns 12 into a plurality of active patterns 16 and branch patterns 18 connected to the inner edge 14a of the peripheral patterns 14, and also cut the peripheral patterns 14 into a plurality of peripheral block patterns 14'. The active patterns 16 thus obtained extend along the first direction D1, and are aligned along the first direction D1 and the second direction D2 to form an array, wherein the ends 16a of the active patterns 16 that are continuously adjacent (continuous adjacent to one another) along the second direction D2 are cut along the second direction D2 (e.g., cut along the extension line LD2 in fig. 3), and the ends 16a and 18a of the active patterns 16 and the branch patterns 18 that are continuously adjacent along the second direction D2 are also cut along the second direction D2. The method of cutting the stripe pattern 12 using the trench pattern 22 of the present invention can obtain the array of active patterns 16 in a close arrangement, and has a large process margin, which is convenient for manufacturing.

As shown in fig. 4, after the second pattern layer 20 is removed, the substrate 100 is etched using the first pattern layer 10 as a mask, and a portion of the substrate 100 exposed from the first pattern layer 10 is removed, so that an isolation trench (not shown) is formed in the substrate 100, and an active pattern 116, a peripheral pattern 114 and a branch pattern 118 are defined in the substrate 100 by the isolation trench. An isolation structure 120 is then formed to fill the isolation trench of the substrate 100 to achieve electrical isolation between the active patterns 116 and to provide a planar surface for subsequent processes to fabricate other structures on the substrate 100.

The method of fabricating the isolation structure 120 may include first performing an oxidation process (e.g., thermal oxidation or in-situ steam oxidation (ISSG)) to oxidize a portion of the substrate 100, and growing a first insulating layer 122 (e.g., a silicon oxide (SiOx) layer) along edges of the active pattern 116, the peripheral pattern 114 (the peripheral block pattern 114'), and the branch pattern 118. It is noted that the thickness of the first insulating layer 122 can be controlled by controlling the oxidation time, so that the first insulating layer 122 can completely fill the isolation trenches surrounded by the inner sides of the peripheral patterns 114 (including the isolation trenches between the active patterns 116, and the isolation trenches among the active patterns 116, the peripheral patterns 114, and the branch patterns 118) with the first insulating layer 122. In other embodiments, the first insulating layer 122 may be formed by a deposition process (e.g., an atomic layer deposition process) with excellent gap filling capability, such that the first insulating layer 122 completely fills the isolation trench inside the peripheral pattern 114. After the first insulating layer 122 is formed, a deposition process (e.g., a chemical vapor deposition process, a physical vapor deposition process, or an atomic layer deposition process) may be performed to sequentially form the second insulating layer 124 and the third insulating layer 126 on the substrate 100 and to completely fill the isolation trench outside the peripheral pattern 114 with the third insulating layer 126, and then a planarization process (e.g., a chemical mechanical polishing process) is performed to remove the excess third insulating layer 126, the second insulating layer 126, and the first insulating layer 122 outside the isolation trench until the top surfaces of the active pattern 116, the peripheral pattern 114, and the branch pattern 118 are exposed, so as to obtain the semiconductor structure shown in fig. 4. The second and third insulating layers 124 and 126, respectively, may comprise a dielectric material. In some embodiments, the second insulating layer 124 preferably comprises silicon nitride (SiN), which can reduce edge dishing (divot) of the first insulating layer 122 sandwiched between the second insulating layer 124 and the outer edge 114e of the peripheral pattern 114 after the subsequent manufacturing process. The third insulating layer 126 is a main filling material of the isolation trench outside the surrounding pattern 114, and may include silicon oxide (SiOx) or a low dielectric constant (low-k) dielectric material.

Please continue to refer to fig. 4. The semiconductor structure provided by the utility model comprises a substrate 100, a plurality of active patterns 116 arranged in the substrate 100, a peripheral pattern 114 surrounding the active patterns 116, and a branch pattern 118 connected to the inner edge 114a of the peripheral pattern 114. The isolation structure 120 is disposed in the substrate 100, surrounding the peripheral pattern 114 and filling between the peripheral pattern 114, the active pattern 116, and the branch pattern 118. The active patterns 116 respectively have lengths extending along the first direction D1, and are aligned in an array along the first direction D1 and the second direction D2, so that the end portions 16a of the active patterns 16 continuously adjacent along the first direction D1 are aligned along the first direction D1 (e.g., along the extension line LD1 of fig. 4), and the end portions 16a of the active patterns 16 continuously adjacent along the second direction D2 are aligned along the second direction D2 (e.g., along the extension line LD2 of fig. 4). The surrounding pattern 114 surrounds the array of active patterns 116 and is divided into a plurality of surrounding block patterns 114' by a plurality of trenches CT1, wherein the edge of the trench CT1 is substantially located on the same extension line (e.g., the extension line LD2 of fig. 4) along the second direction D2 as the end 116a of the active pattern 116. The branch pattern 118 has a length extending along the first direction D1, and is located on an extension line (e.g., the extension line LD1 of fig. 4) of the active pattern 116 along the first direction D1. The end portion 118a of the branch pattern 118 and the end portion 116a of the active pattern 116 immediately adjacent (first adjacent) along the second direction D2 may be aligned along the second direction D2 (e.g., aligned along the extension line LD2 of fig. 4). The isolation structure 120 is used to electrically isolate the active patterns 116, and also to fill up isolation trenches of the substrate 100 to facilitate subsequent processes for fabricating other structures on the substrate 100. As shown in fig. 4, the isolation structure 120 is formed of at least three layers of insulating materials, including a first insulating layer 122 disposed between the active patterns 116 and surrounding the outer edges 114e of the surrounding patterns 114, a second insulating layer 124 surrounding the outer edges 114e of the surrounding patterns 114 and separated from the surrounding patterns 114 by the first insulating layer 112, and a third insulating layer 126 surrounding the second insulating layer 124. The design of the active pattern 116, the surrounding pattern 114 and the branch pattern 118 of the present invention can simplify the manufacturing process, and the isolation trenches surrounded by the inside of the surrounding pattern 114 (including the isolation trenches between the active patterns 116 and the isolation trenches between the active patterns 116, the surrounding pattern 114 and the branch pattern 118) can have more uniform dimensions, so that the isolation trenches can be more easily and completely filled by the first insulating layer 122, thereby avoiding the chance of other materials (such as the second insulating layer 124) filling the isolation trenches inside the surrounding pattern 114. In this way, it is ensured that when the buried word lines (buried word lines) are fabricated subsequently, the trenches of the buried word lines passing through the memory array region will only cut through the materials of the substrate 100 and the first insulating layer 122, and the problem of excessive shrinkage of the line width due to cutting through other materials will not occur. In addition, the design of the present invention for connecting the branch pattern 118 to the peripheral pattern 114 can enhance the structural support and stress buffering effect of the peripheral pattern 114.

The following description will be directed to various embodiments of the utility model. For simplicity, the following description mainly describes the differences between the embodiments, and the descriptions of the same parts are not repeated. Like elements in the various embodiments are labeled with like reference numerals to facilitate the comparison between the various embodiments.

Referring to fig. 5 and 6, a variation of the steps shown in fig. 3 and 4 will be described. As shown in fig. 5, the length of the trench pattern 22 of the second pattern layer 20 (refer to fig. 2) may be adjusted so as not to extend beyond the outer edge 14e of the peripheral pattern 14, so that the inner edge 14a of the peripheral pattern 14 obtained by etching the first pattern layer 10 with the second pattern layer 20 as a mask is etched to form a notch portion (notch portion)14 b. Unlike the surrounding pattern 14 of fig. 3 that is cut into a plurality of blocks, the surrounding pattern 14 of fig. 5 may have a continuous closed loop pattern. Then, as shown in fig. 6, the peripheral pattern 114 obtained by etching the substrate 100 using the first pattern layer 10 as a mask has a cut portion 114b at an inner edge 114a thereof, and an edge of the cut portion 114b is substantially located on the same extension line (e.g., the extension line LD2 of fig. 6) along the second direction D2 as the end portion 116a of the active pattern 116.

Referring to fig. 7 and 8, another variation of the steps shown in fig. 3 and 4 is illustrated. As shown in fig. 7, a plurality of arc-shaped trenches 14c cut into the peripheral pattern 14 from the inner edge 14a of the peripheral pattern 14 are formed in the first pattern layer 10 by forming a ring-shaped trench pattern 22 in the second pattern layer 20 (refer to fig. 2) by using a sidewall sub-pattern transfer technique or other suitable techniques, and then etching the first pattern layer 10 by using the second pattern layer 20 as a mask. Then, as shown in fig. 8, a surrounding pattern 114 obtained by etching the substrate 100 using the first pattern layer 10 as a mask has a profile as the surrounding pattern 14. A plurality of arcuate grooves CT2 are cut into the peripheral pattern 114 from the inner edge 114a of the peripheral pattern 114.

Fig. 9 to fig. 11 are schematic plan views illustrating different steps of a semiconductor structure in a manufacturing process according to another embodiment of the utility model. The main difference between this embodiment and the embodiment shown in fig. 1 to 4 is that the first pattern layer 101 of this embodiment is an upper layer portion of the substrate 100 that is patterned, and is not another material layer disposed on the substrate 100. In this embodiment, after the stripe patterns 102 and the surrounding patterns 114 are formed in the substrate 100, the stripe patterns 102 of the substrate 100 are cut to form the active patterns 116. In detail, as shown in fig. 9, an isolation trench SP may be formed in the substrate 100 through a patterning process (e.g., a photolithography and etching process) to define a stripe pattern 102 and a surrounding pattern 114 in the substrate 100, and then an isolation structure 120 is formed to fill the isolation trench SP of the substrate 100. The isolation structure 120 includes a first insulating layer 122 between the bar patterns 102 and surrounding the outer edges 114e of the peripheral patterns 114, a second insulating layer 124 surrounding the outer edges 114e of the peripheral patterns 114 and separated from the peripheral patterns 114 by the first insulating layer 112, and a third insulating layer 126 surrounding the second insulating layer 124. The method for fabricating the isolation structure 120 can refer to the foregoing description, and will not be repeated here. Next, as shown in fig. 10, a second pattern layer 20 is formed on the substrate 100 and covers the bar patterns 102, the surrounding patterns 114 and the isolation structures 120, and then a patterning process (e.g., a photolithography and etching process) is performed on the second pattern layer 20 to form a plurality of trench patterns 22 extending along the second direction D2 and arranged in parallel in the second pattern layer 20, exposing portions of the bar patterns 102, the surrounding patterns 114 and the isolation structures 120. Next, as shown in fig. 11, the bar-shaped patterns 102, the peripheral patterns 114 and the isolation structures 120 exposed from the trench patterns 22 are etched by using the second pattern layer 20 as a mask, so as to form trenches CT3 extending along the second direction D2 in the substrate 100, the bar-shaped patterns 102 are cut into a plurality of active patterns 116 and branch patterns 118 connected to the inner edges 114a of the peripheral patterns 114 by the trenches CT3, and the peripheral patterns 114 are cut into a plurality of peripheral block patterns 114'. The trench CT3 may also extend through the first and second insulating layers 122 and 124 around the outside of the surrounding pattern 114, so that the first and second insulating layers 122 and 124 around the outside edge 114e of the surrounding pattern 114 are discontinuous in plan view. A fourth insulating layer 128 may be subsequently formed to fill the trench CT3 to achieve electrical isolation between the active patterns 116 and to provide a planar surface to facilitate subsequent processing to fabricate other structures on the substrate 100. The fourth insulating layer 128 may include a dielectric material, such as silicon oxide (SiOx) or a low dielectric constant (low-k) dielectric material. According to an embodiment of the present invention, the fourth insulating layer 128 and the first insulating layer 122 may comprise the same material, such as silicon oxide.

Referring to fig. 12, a variation of the semiconductor structure of fig. 11 is illustrated. The length of the trench pattern 22 of the second patterning layer 20 (see fig. 10) may be adjusted so as not to extend beyond the outer edge 114e of the peripheral pattern 114, so that the end of the trench CT3 obtained by etching the substrate 110 and the isolation structure 120 with the second patterning layer 20 as a mask cuts into the inner edge 114a of the peripheral pattern 114 to form the cut portion 114 b. Unlike the surrounding pattern 114 of fig. 11 being cut into a plurality of surrounding block patterns 114', the surrounding pattern 114 of fig. 12 has a continuous closed-loop pattern, and the second insulating layer 124 is also a continuous closed-loop pattern.

Referring to fig. 13, another variation of the semiconductor structure shown in fig. 11 is illustrated. A double patterning process, such as a sidewall sub-pattern transfer or other suitable process, may be used to form the annular trench pattern 22 in the second pattern layer 20 (see fig. 10), so that an arc-shaped trench CT4 cut into the peripheral pattern 114 from the inner edge 114a of the peripheral pattern 114 is formed after etching the substrate 110 and the isolation structure 120 through the annular trench pattern 22 by using the second pattern layer 20 as a mask. The arc-shaped groove CT4 is connected to the groove CT3 to form a circular pattern.

In summary, the present invention provides a semiconductor structure and a method for fabricating the same, which can obtain a closely arranged array of active patterns and a surrounding pattern surrounding the array of active patterns by cutting a stripe pattern through a plurality of parallel trenches (e.g., cutting a hard mask layer and then transferring the pattern of the hard mask layer into a substrate, or directly cutting the stripe pattern of the substrate). The surrounding pattern may provide structural support and stress buffering around the active pattern array. In addition, the branch pattern connected to the edge of the peripheral pattern can make the periphery of the active pattern array have more uniform pattern density, and the first insulating layer can more easily and completely fill the gap between the active pattern and the peripheral pattern.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A semiconductor structure, comprising:

a substrate;

a plurality of active patterns disposed in the substrate, respectively extending along a first direction, and aligned along the first direction and a second direction;

a surrounding pattern disposed in the substrate and surrounding the plurality of active patterns; and

at least one branch pattern connected to an inner edge of the surrounding pattern and extending along the first direction, wherein an end of the branch pattern is aligned with an end of an adjacent active pattern along the second direction.

2. The semiconductor structure of claim 1, wherein an angle between the first direction and the second direction is between 15 degrees and 130 degrees.

3. The semiconductor structure of claim 1, wherein the branch pattern and at least one active pattern are located on a same extension line along the first direction.

4. The semiconductor structure of claim 1, further comprising a plurality of trenches cut through the peripheral pattern to divide the peripheral pattern into a plurality of peripheral block patterns, wherein the trenches and an end of at least one of the active patterns are located on a same extension line along the second direction.

5. The semiconductor structure of claim 1, wherein the surrounding pattern is a closed loop pattern.

6. The semiconductor structure of claim 1, wherein the inner edge of the peripheral pattern comprises at least one cut-out portion, the cut-out portion being located on a same extension line along the second direction as an end of at least one of the active patterns.

7. The semiconductor structure of claim 1, further comprising a plurality of arcuate trenches cut into said peripheral pattern from said inner edge.

8. The semiconductor structure of claim 1, further comprising:

a first insulating layer between the active patterns and surrounding an outer edge of the surrounding pattern;

a second insulating layer surrounding said outer edge of said peripheral pattern and separated from said peripheral pattern area by said first insulating layer; and

and the third insulating layer surrounds the second insulating layer.

9. The semiconductor structure of claim 8, further comprising a fourth insulating layer between ends of the active patterns that are immediately adjacent along the first direction.

10. The semiconductor structure of claim 8, wherein the second insulating layer is a discontinuous structure.

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