FIN MASK AND METHOD FOR FABRICATING SADDLE TYPE FIN USING THE SAME
A fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis includes a first fin mask of a line type, and a second fin mask of an island type, wherein the first fin mask and the second fin mask in combination expose saddle type fin regions and cover ends of the neighboring active regions along the major axis.
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The present invention claims priority of Korean patent application numbers 10-2006-0061437 and 10-2006-0128839, filed on Jun. 30, 2006 and Dec. 15, 2006, respectively, which are incorporated by reference in their entirety.
BACKGROUND OF THE INVENTIONThe present invention relates to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a saddle type transistor having a saddle type fin.
A typical cell in a three-dimensional structure for use in a dynamic random access memory (DRAM) cell includes a fin structure, a recess channel structure, and a saddle type structure. The saddle type structure includes the fin structure and the recess channel structure in combination.
The typical method as described above uses the line type fin mask 13 to form the saddle type fins 14. However, in the typical method, the active region 11A is exposed by the line type fin mask 13 at regions predetermined for forming the saddle type fins 14 as well as at the ends of the active region 11A along the major axis. Thus, dummy saddle type fins 14A may be formed. The dummy saddle type fins 14A may be formed in an active region that will be connected to a storage node. Thus, leakage of the storage node and capacitance of the gate may be increased, deteriorating performance of the transistor.
SUMMARY OF THE INVENTIONEmbodiments of the present invention are directed towards providing a fin mask and a method for fabricating a saddle type fin using the same, which can reduce formation of undesired dummy saddle type fins at the end of an active region along a major axis.
In accordance with an aspect of the present invention, there is provided a fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask including: a first fin mask of a line type; and a second fin mask of an island type, wherein the first fin mask and the second fin mask in combination expose saddle type fin regions and cover ends of the neighboring active regions along the major axis.
In accordance with another aspect of the present invention, there is provided a fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask including: a first fin mask of a line type; and a second fin mask having openings, wherein the first fin mask and the second fin mask in combination expose saddle type fin regions and cover ends of the neighboring active regions along the major axis.
In accordance with a still another aspect of the present invention, there is provided a fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask including island-shaped openings exposing saddle type fin regions and covering the rest of the active regions.
In accordance with a further aspect of the present invention, there is provided a method for fabricating a saddle type fin, including: providing a substrate defining at least two active regions that have neighboring ends in a major axis; forming an etch barrier pattern over the substrate, the etch barrier pattern exposing saddle type fin regions of the active regions and covering the rest of the active regions; and etching the saddle type fin regions to form saddle type fins in a local damascene structure, wherein forming the etch barrier pattern includes forming a first fin mask and a second fin mask, and wherein the first fin mask exposes the saddle type fin regions in a line pattern and the second fin mask covers the neighboring ends of the active regions.
The present invention relates to a fin mask and a method for fabricating a saddle type fin using the same. Formation of dummy saddle type fins at the ends of neighboring active regions along a major axis may be reduced through using a fin mask combination that locally opens saddle type fin regions. Thus, leakage of the storage node and increased gate capacitance caused by the dummy saddle type fins may be reduced.
The active region 101 is defined by the isolation structure 102. Forming a fin mask according to the first embodiment includes using a first fin mask FM1 and a second fin mask FM2 in combination to form saddle type fins 103. The active region 101 and the isolation structure 102 are selectively etched to form the saddle type fins 103, that is, the active region 101 protruding in a saddle type structure. In the present embodiment, the first fin mask FM1 and the second fin mask FM2 may be sequentially used according to a given order, and the given order may be changeable. For instance, the first fin mask FM1 may be formed first and the second fin mask FM2 may be formed after the first fin mask FM1 is removed. On the other hand, the second fin mask FM2 may be formed first and the first fin mask FM1 may be formed after the second fin mask FM2 is removed. However,
The first fin mask FM1 is a line type mask that is formed along a first direction, and the second fin mask FM2 is an island type mask that is formed along a second direction that is orthogonal to the first direction. Using the first fin mask FM1 and the second fin mask FM2 in combination allows selectively etching portions of the active region 101 and the isolation structure 102 predetermined for forming the saddle type fins 103. That is, portions where dummy saddle type fins usually occur (i.e., the ends 104 along the major axis of two neighboring active regions 101 along the X axis) are not etched during an etching process for forming the saddle type fins 103. This result may be obtained because the island type second fin mask FM2 is applied.
For instance, the second fin mask FM2 may be an island type mask of a rectangular shape formed to cover the ends 104 along the major axis of the neighboring active regions 101 and cover the isolation structure 102 between the two active regions 101. The second fin mask FM2 is formed at least partly to intersect the location where the first fin mask FM1 was formed. The first fin mask FM1 and the second fin mask FM2 may be applied in a certain order. A hard mask pattern transcribing the shape of the first fin mask FM1 and the second fin mask FM2 in combination is used as an etch barrier when forming the saddle type fins 103.
Referring to
An amorphous carbon layer 25, a dielectric anti-reflective coating (DARC) layer 26, a polysilicon hard mask 27, and a first patterned bottom anti-reflective coating (BARC) layer 28A are formed over the resulting substrate structure. In more detail, the amorphous carbon layer 25, the DARC layer 26, a polysilicon hard mask layer, and a first BARC layer are formed over the substrate structure. The selectivity between the DARC layer 26 and the amorphous carbon layer 25 is approximately 10:1 or higher. Thus, the DARC layer 26 functions as a hard mask when etching the amorphous carbon layer 25. The polysilicon hard mask layer functions as a hard mask when etching the DARC layer 26. Both the DARC layer 26 and the polysilicon hard mask layer may have a thickness of approximately 1,000 Å or less. The amorphous carbon layer 25 may be used as a hard mask for forming a subsequent saddle type fin. The amorphous carbon layer 25 may have a thickness of approximately 500 Å or greater.
A first fin mask (FM1) 29 is formed over the first BARC layer. The FM1 29 includes a photoresist layer patterned by a photo-exposure and developing process. The FM1 29 includes line type first openings 29A exposing saddle type fin regions. That is, the FM1 29 is formed in a line mask shape, wherein the first openings 29A are formed to intersect with the major axis of the active region 21A. The active region 21A and the FM1 29 are disposed in substantially the same manner as the active regions 101 and the first fin mask FM1 shown in
An etching process is performed to etch the first BARC layer and the polysilicon hard mask layer using the FM1 29 as an etch mask. Consequently, the first patterned BARC layer 28A and the polysilicon hard mask 27 are formed. Thus, the polysilicon hard mask 27 is formed in a line type pattern, transcribing the shape of the FM1 29.
Referring to
Referring to
Referring to
The amorphous carbon pattern 25A prevents the etching of the ends of two neighboring active regions 21A along the major axis when forming the saddle type fins 31. Consequently, only the saddle type fin regions (refer to line B-B′) of the active region 21A and the isolation structure 24 are etched. The active regions 21A and the isolation structure 24 at the ends of the active regions 21A along the major axis where the dummy saddle type fins often occur may not be etched. The resultant saddle type fins 31 are described in a plan view in
Accordingly, forming the saddle type fins 31 by etching using the amorphous carbon pattern 25A reduces the etching of the ends of the active regions 21A along the major axis. Thus, the dummy saddle type fins are not formed. The saddle type fin regions to be etched are defined in a rectangular shape by the rectangular type openings 100A and are locally etched. Thus, the saddle type fins 31 according to the first embodiment may be referred to as local damascene saddle type fins (LD-SF).
In the aforementioned first embodiment, the line type FM1 29 is used before using the island type FM2 30. However, an amorphous carbon pattern having substantially the same shape as the one shown in
A plurality of active regions 111 are formed in a substrate. The substrate has a flat surface with an X axis and a Y axis. The active regions 111 are formed in a particular size with a major axis and a minor axis. The active regions 111 are disposed in a manner that the ends 114 along the major axis of two neighboring active regions 111 along the X axis are adjacent to each other, and an isolation structure 112 is formed between the adjacent active regions 111. Hereinafter, only one set of elements are described for convenience.
The active region 111 is defined by the isolation structure 112. Forming a fin mask according to the second embodiment includes using a first fin mask FM11 and a second fin mask FM21 in combination to form saddle type fins 113. The active region 111 and the isolation structure 112 are selectively etched to form the saddle type fins 113, that is, the active region 111 protruding in a saddle type structure. In the present embodiment, the first fin mask FM11 and the second fin mask FM21 may be sequentially used according to a given order, and the given order may be changeable. For instance, the first fin mask FM11 may be formed first and the second fin mask FM21 may be formed after the first fin mask FM11 is removed. On the other hand, the second fin mask FM21 may be formed first and the first fin mask FM11 may be formed after the second fin mask FM21 is removed. However,
The first fin mask FM11 is a line type mask that is formed along a first direction, and the second fin mask FM21 is an island type mask that is formed along a second direction that is orthogonal to the first direction. The saddle type fin regions of the active region 111 and the isolation structure 112, where the saddle type fins 113 are to be formed, may be locally etched by combining the two fin masks. That is, portions where dummy saddle type fins usually occur (i.e., the ends 114 along the major axis of two neighboring active regions 111 along the X axis) are not etched during an etching process for forming the saddle type fins 113. This result may be obtained because the island type second fin mask FM21 is applied.
For instance, the second fin mask FM21 may be a dumbbell-shaped island type mask formed to cover the ends 114 along the major axis of the neighboring active regions 111 and cover the isolation structure 112 between the two active regions 111. The dumbbell-shaped island type mask includes a rectangular shape over the isolation structure 112 between the neighboring active regions 111. The dumbbell-shaped island type mask also includes a ball or an ellipse shape over the ends 114 of each active region 111 such that the dumbbell-shaped island type mask covers the ends 114 with an increased surface area. The second fin mask FM21 is formed to intersect at least partly the location where the first fin mask FM11 was formed.
The second fin mask FM21 is formed as the dumbbell-shaped island type mask according to the second embodiment unlike the second fin mask FM2 that is formed as a rectangular island type mask according to the first embodiment. Using the second fin mask FM21 of the dumbbell-shaped island type may increase the margin for covering the ends 114 of the active region 111. That is, the margin for reducing the chances of dummy saddle type fin generation at the ends 114 of the active region 111 may increase.
The first fin mask FM11 and the second fin mask FM21 may be applied in a certain order (i.e., FM11→FM21 or FM21→FM11). A hard mask pattern transcribing the shape of the first fin mask FM11 and the second fin mask FM21 in combination is used as an etch barrier when forming the saddle type fins 113. The etch barrier may include an amorphous carbon pattern. The amorphous carbon pattern may be formed by employing the first fin mask FM11, the second fin mask FM21, a DARC layer, and a polysilicon hard mask. The amorphous carbon pattern may be formed using the method shown in
The first fin mask FM31 is a line type mask exposing only the saddle type fin regions of the active regions 200, where the saddle type fins 201 are to be formed. The first fin mask FM31 is substantially the same as the first fin masks according to the first and second embodiments. The second fin mask FM32 is a jigsaw puzzle type mask. That is, the second fin mask FM32 having the jigsaw puzzle shape covers ends of the active regions 200 along a major axis as well as between the ends. Meanwhile, the second fin mask FM32 exposes the rest of the substrate structure through jigsaw puzzle openings 202. Regions exposed by the jigsaw puzzle openings 202 are locally etched to form the saddle type fins 201.
Using the second fin mask FM32 of jigsaw puzzle type according to the third embodiment may allow the selectivity of a photoresist layer to be maintained, which may otherwise be insufficient. Thus, the ends of the active regions 200 along the major axis where dummy saddle type fins often occur may be sufficiently covered.
The first fin mask FM31 and the second fin mask FM32 are applied in a certain order (i.e., FM31→M32 or FM32→FM31). A hard mask pattern transcribing the shape of the first fin mask FM31 and the second fin mask FM32 in combination is used as an etch barrier pattern when forming the saddle type fins 201. The etch barrier pattern may include an amorphous carbon pattern. The amorphous carbon pattern may be formed by employing the first fin mask FM31, the second fin mask FM32, a DARC layer, and a polysilicon hard mask. The amorphous carbon pattern may be formed using the method shown in
Referring to
Using the fin mask R-FM having the island-shaped openings 302 independently may simplify the process when compared to using two fin masks. Also, using the fin mask R-FM according to the fourth embodiment generally does not require using a polysilicon hard mask. The saddle type fins 301 may be formed using only amorphous carbon. The saddle type fins 301 may include polysilicon instead of amorphous carbon. Therefore, a hard mask stack may be simply configured using the fin mask R-FM according to the fourth embodiment. For instance, an etch barrier pattern transcribing the shape of the fin mask R-FM is used as an etch barrier when forming the saddle type fins 301 using the fin mask R-FM according to the fourth embodiment. The etch barrier pattern may include an amorphous carbon pattern or a polysilicon pattern. The etch barrier pattern may be formed by employing the fin mask R-FM and a DARC layer. The etch barrier pattern may be formed using the method shown in
Saddle type fins may be formed in a local damascene form when the saddle type fins are formed using the fin mask combination or the independent fin mask R-FM according to the first to the fourth embodiments. Since the saddle type fin regions are limited and locally etched, the saddle type fins become local damascene saddle type fins (LD-SF).
While the present invention has been described with respect to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
Claims
1. A fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask comprising:
- a first fin mask of a line type; and
- a second fin mask of an island type,
- wherein the first fin mask and the second fin mask in combination expose saddle type fin regions and cover ends of the neighboring active regions along the major axis.
2. The fin mask of claim 1, wherein the second fin mask has a rectangular shape overlapping the first fin mask.
3. The fin mask of claim 1, wherein the second fin mask is formed in a rectangular shape overlapping the first fin mask, wherein portions of the second fin mask covering the ends of the active regions along the major axis have a larger surface area than the ends of the active regions.
4. The fin mask of claim 3, wherein the portions of the second fin mask covering the ends of the active regions along the major axis are formed in a ball or an ellipse shape.
5. A fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask comprising:
- a first fin mask of a line type; and
- a second fin mask having openings,
- wherein the first fin mask and the second fin mask in combination expose saddle type fin regions and cover ends of the neighboring active regions along the major axis.
6. The fin mask of claim 5, wherein the openings of the second fin mask are formed in an island shape, wherein the island shape includes a jigsaw puzzle shape.
7. A fin mask for forming saddle type fins in each of active regions formed in an island shape having a certain size with a major axis and a minor axis, the fin mask comprising island-shaped openings exposing saddle type fin regions and covering the rest of the active regions.
8. The fin mask of claim 7, wherein the openings are formed in a rectangular or an ellipse shape.
9. A method for fabricating a saddle type fin, the method comprising:
- providing a substrate defining at least two active regions that have neighboring ends in a major axis;
- forming an etch barrier pattern over the substrate, the etch barrier pattern exposing saddle type fin regions of the active regions and covering the rest of the active regions; and
- etching the saddle type fin regions to form saddle type fins in a local damascene structure,
- wherein forming the etch barrier pattern comprises forming a first fin mask and a second fin mask, and
- wherein the first fin mask exposes the saddle type fin regions in a line pattern and the second fin mask covers the neighboring ends of the active regions.
10. The method of claim 9, wherein the first fin mask is a line type and the second fin mask is an island type, the second fin mask being formed after the first fin mask is removed.
11. The method of claim 10, wherein the second fin mask is formed in an island pattern comprising a rectangular shape overlapping the first fin mask, wherein portions of the second fin mask covering the ends of the active regions have a larger surface area than the ends of the active regions.
12. The method of claim 11, wherein the portions of the second fin mask covering the ends of the active regions have a round shape.
13. The method of claim 10, wherein the etch barrier pattern formed by the first and second fin masks in combination comprises an amorphous carbon pattern.
14. The method of claim 13, wherein forming the amorphous carbon pattern comprises:
- forming an amorphous carbon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the amorphous carbon layer;
- forming a polysilicon layer over the DARC layer;
- etching the polysilicon layer using the first fin mask;
- etching the DARC layer using the second fin mask; and
- etching the amorphous carbon layer using the DARC layer.
15. The method of claim 13, wherein forming the amorphous carbon pattern comprises:
- forming an amorphous carbon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the amorphous carbon layer;
- forming a polysilicon layer over the DARC layer;
- etching the polysilicon layer using the second fin mask;
- etching the DARC layer using the first fin mask; and
- etching the amorphous carbon layer using the DARC layer.
16. The method of claim 9, wherein forming the etch barrier pattern comprises forming a first fin mask and a second fin mask in combination, wherein the first fin mask exposes the saddle type fin regions in a line shape and the second fin mask exposes the saddle type fin regions in an island pattern comprising a jigsaw puzzle shape and covers the neighboring ends of the active regions.
17. The method of claim 16, wherein the etch barrier pattern formed by the first and second fin masks in combination comprises an amorphous carbon pattern.
18. The method of claim 17, wherein forming the amorphous carbon pattern comprises:
- forming an amorphous carbon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the amorphous carbon layer;
- forming a polysilicon layer over the DARC layer;
- etching the polysilicon layer using the first fin mask;
- etching the DARC layer using the second fin mask; and
- etching the amorphous carbon layer using the DARC layer.
19. The method of claim 17, wherein forming the amorphous carbon pattern comprises:
- forming an amorphous carbon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the amorphous carbon layer;
- forming a polysilicon layer over the DARC layer;
- etching the polysilicon layer using the second fin mask;
- etching the DARC layer using the first fin mask; and
- etching the amorphous carbon layer using the DARC layer.
20. The method of claim 9, wherein forming the etch barrier pattern comprises using a fin mask having openings exposing the saddle type fins and covering the rest regions.
21. The method of claim 20, wherein the openings are formed in a rectangular or an ellipse shape.
22. The method of claim 20, wherein the etch barrier pattern comprises an amorphous carbon pattern or a polysilicon pattern.
23. The method of claim 22, wherein forming the amorphous carbon pattern comprises:
- forming an amorphous carbon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the amorphous carbon layer;
- etching the DARC layer using the fin mask; and
- etching the amorphous carbon layer using the DARC layer.
24. The method of claim 22, wherein forming the polysilicon pattern comprises:
- forming a polysilicon layer;
- forming a dielectric anti-reflective coating (DARC) layer over the polysilicon layer;
- etching the DARC layer using the fin mask; and
- etching the polysilicon layer using the DARC layer.
Type: Application
Filed: Feb 26, 2007
Publication Date: Jan 3, 2008
Applicant: Hynix Semiconductor Inc. (Icheon-si)
Inventor: Kwang-Ok Kim (Ichon-shi)
Application Number: 11/679,179
International Classification: H01L 21/336 (20060101); H01L 27/108 (20060101);