# Patent

## Title
Method for manufacturing semiconductor device with SEG film active region

## Abstract

A semiconductor device and a method for manufacturing the same are provided. A barrier film is formed in a device separating structure, and the device separating structure is etched at a predetermined thickness to expose a semiconductor substrate. Then, a SEG film is grown to form an active region whose area is increased. As a result, a current driving power of a transistor located at a cell region and peripheral circuit regions is improved.

## Background
CROSS-REFERENCES TO RELATED APPLICATIONS
The present application is a divisional of U.S. patent application Ser. No. 11/637,165, filed on Dec. 12, 2006, which claims priority to Korean patent application number 10-2006-0048670, filed on May 30, 2005, both of which are incorporated by reference in their entirety.


BACKGROUND OF THE INVENTION
The present invention generally relates to a semiconductor device and its method of manufacture, and, more specifically, to a method for forming a barrier film in a device separating structure, etching the device separating structure at a predetermined depth to expose a semiconductor substrate, and growing a SEG film to form an active region having an increased area.
FIG. 1 is a plane diagram illustrating a conventional semiconductor device.
Referring to FIG. 1, a recess gate 20 is formed perpendicular to an active region 10 in a semiconductor substrate having a device separating structure that defines the active region 10.
When a trench for defining the active region is formed over the semiconductor substrate and then filled with an oxide film to form a device separating structure, the area of the active region is decreased due to recent decrease in the size of the semiconductor device.
In the above-described method for manufacturing a semiconductor device, after the device separating structure is formed, the semiconductor substrate of the active region is etched at a predetermined thickness to form a recess gate region and a gate pattern. However, the area of the active region is decreased as the design rule is decreased. As a result, the current driving power is degraded as much as the decreased area of the active region.
BRIEF SUMMARY OF THE INVENTION
Various embodiments of the present invention are directed at providing a semiconductor device and its method of manufacture, which includes forming a barrier film in a device separating structure, etching the device separating structure at a predetermined depth to expose a semiconductor substrate, and growing a SEG film to form an active region whose area is increased.
According to an embodiment of the present invention, a semiconductor device comprises a first device separating structure that defines a first active region, a second device separating structure extended to the side surface of the first active region so as to define a second active region overlapped with the first device separating structure, a line-type barrier film extended along the major axis of the active regions and formed in a device separating region between the active regions, and a recess gate perpendicular to the active region and having a recess formed in the active region.
According to an embodiment of the present invention, a method for manufacturing a semiconductor device comprises the steps of: forming a first device separating structure that defines a first active region over a semiconductor substrate; forming a trench in a predetermined region of the first device separating structure; forming a barrier film for filling the trench; etching the first device separating structure at a predetermined depth to expose the sidewall of the first active region; growing the first active region to form a SEG film between the first active region and the barrier film, thereby forming a second active region extended from the first active region to the side; and, forming a second device separating structure between the second active region.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plane diagram illustrating a conventional semiconductor device.
FIG. 2 is a plane diagram illustrating a semiconductor device according to an embodiment of the present invention.
FIGS. 3a through 3i are cross-sectional diagrams illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.



DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENT
The present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 is a plane diagram illustrating a conventional semiconductor device.
Referring to FIG. 2, a first device separating structure that defines a first active region and a second device separating structure extended to the side surface of the first active region so as to define a second active region overlapped with the first device separating structure are formed over a semiconductor substrate.
The second active region is formed from a SEG film over the first device separating structure.
A line-type barrier film 120 is extended along a major axis direction of an active region 127 and formed in the device separating region between the active regions 127.
The barrier film 120 is formed deeper than the second device separating structure, and obtained by filling a line-type trench formed in the device separating region between the active regions 127.
The trench has a line-width ranging from about 10 to about 100 nm, and a depth ranging from about 300 to about 2000 Å.
The second active region extended to the side surface of the first active region is formed between the first active region and the barrier film 120. The second active region is obtained by growing a SEG film with a silicon layer of the first active region as a seed layer. The SEG film is formed to have the same height as that of the second device separating structure by a planarization process.
A recess gate 175 is formed perpendicular to the active region 127, and has a recess in the active region 127.
FIGS. 3a through 3i are cross-sectional diagrams illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention, FIGS. 3a through 3f show cross-sectional diagrams according to a-a′ of FIG. 2.
Referring to FIG. 3a, a trench for separating a device (not shown) is formed by etching a semiconductor substrate at a predetermined thickness. An oxide film for filling the trench for separating a device (not shown) is formed to obtain a first device separating structure 105 that defines a first active region 100.
Referring to FIG. 3b, after a photoresist film (not shown) is formed over the resulting structure, an exposure and developing process is performed with an exposure mask where a local barrier film is defined, thereby obtaining a photoresist pattern 110.
The exposure mask is extended along the major axis direction of the first active region 100 so that a line-type space pattern is defined in the device separating region between the first active region 100.
Referring to FIG. 3c, the first device separating structure 105 is etched with the photoresist pattern 110 as a mask to form a trench (not shown). Then, a barrier film 120 for filling the trench (not shown) is formed over the resulting structure.
The barrier film 120 is planarized to fill the trench (not shown).
The trench (not shown) has a line-width ranging from about 10 to about 100 nm, and a depth ranging from about 300 to about 2000 Å.
The barrier film 120 is formed from a nitride film, and has a thickness ranging from about 30 to about 500 Å over the first active region 100.
Referring to FIG. 3d, the first device separating structure 105 is etched at a predetermined thickness with the barrier film 120 and the first active region 100 as a mask to expose the sidewall of the first active region 100.
The above etching process is a wet-etching process with a HF or a BOE solution using a etching selectivity between the oxide film, which is the first device separating structure 105, and the nitride film, which is the barrier film 120. The first device separating structure 105 is etched at a depth ranging from about 100 to about 1500 Å so that the barrier film 120 remains ranging from about 33 to 75%.
Referring to FIG. 3e, the SEG film is grown with the silicon layer of the first active region 100 as a seed layer so that the SEG film is extended from the first active region 100 to the side surface to form a second active region 125 overlapped with the first device separating structure 105.
Since the barrier film 120 is formed at both sides of the exposed active region 100, the SEG film is grown into the region having the barrier film 120 so as to have a thickness ranging from about 100 to about 2000 Å thereover.
Referring to FIG. 3f, a second device separating structure 130 is formed between the second active regions 125.
The second device separating structure 130 is formed to have a thickness ranging from about 100 to 2000 Å. Since the second device film 130 is deposited with the first device separating structure 105, it is formed from an oxide film, which is the first device separating structure 105.
(i) of FIG. 3g shows a cross-section taken along a-a′ of FIG. 2, and (ii) of FIG. 3g is a cross-section taken along b-b′ of FIG. 2.
Referring to FIG. 3g, a planarization process is performed to expose the first active region 100 or the barrier film 120.
Referring to (ii) of FIG. 3g, the second device separating structure 130 is deposited over the first device separating structure 105, and etched at a predetermined thickness in FIG. 3d so that it is used as a device separating structure.
Referring to FIG. 3h, the first active region 100 and the second active region 125 are etched at a predetermined thickness to form a recess gate region 140.
FIG. 3i, (i), (ii) and (iii) show cross-sections taken along a-a′, b-b′ and c-c′ of FIG. 2. A gate oxide film (not shown) is formed over the semiconductor substrate including the recess gate region 140. Then, a deposition structure including a polysilicon layer 150, a gate metal layer 160 and a gate hard mask layer 170 is formed.
Next, the deposition structure is patterned to form a gate pattern 175. Then, a spacer 190 is formed at the sidewall of the gate pattern 175.
According to an embodiment of the present invention, a barrier film is formed in a device separating structure, and the device separating structure is etched at a predetermined thickness to expose a semiconductor substrate. Then, a SEG film is grown to form an active region whose area is increased. As a result, a current driving power of a transistor located at a cell region and peripheral circuit regions is improved.
The above embodiments of the present invention are illustrative and not limitative. Various alternatives and equivalents are possible. The invention is not limited by the lithography steps described herein. Nor is the invention limited to any specific type of semiconductor device. For example, the present invention may be implemented in a dynamic random access memory (DRAM) device or nonvolatile memory device. Other additions, subtractions, or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims.

## Claims

1. A method for manufacturing a semiconductor device, the method comprising the acts of:
forming a first device separating structure that defines a plurality of first active regions over a semiconductor substrate;
forming a trench in a predetermined region of the first device separating structure;
forming a barrier film so as to fill the trench;
etching the first device separating structure to a predetermined depth to expose sidewalls of the first active regions and a top portion of the barrier film formed in the trench;
growing a selective epitaxial growth (SEG) film from each of the exposed sidewalls of the first active regions, thereby forming second active regions, each of the second active regions extending from one of the exposed sidewalls of the first active regions to contact the top portion of the barrier film so that each second active region is in part defined by the barrier film; and
forming a second device separating structure so that each of the second active regions is between and in contact with at least a portion of the second device separating structure and a top portion of one of the first active regions.

2. The method according to claim 1, wherein the act of forming a trench includes:
forming a photoresist film over the first device separating structure and the first active regions;
forming a photoresist pattern by an exposure and developing process with an exposure mask; and
etching the first device separating structure with the photoresist pattern as a mask to form the trench.

3. The method according to claim 2, wherein the exposure mask is extended along a major axis of the first active regions so that it is defined as a line-type space pattern formed in the first device separating structure between first active regions.

4. The method according to claim 1, wherein the line-width of the trench ranges from about 10 to about 100 nm.

5. The method according to claim 1, wherein the depth of the trench ranges from about 300 to about 2000 Å.

6. The method according to claim 1, wherein the act of forming a barrier film includes:
forming a nitride film for filling the trench over the first device separating structure and the first active regions; and
planarizing the nitride film to form a barrier film filling the trench.

7. The method according to claim 6, wherein the thickness of the nitride film ranges from about 30 to about 500 Å.

8. The method according to claim 1, wherein the act of etching the first device separating structure is performed with the barrier film and the first active regions as a mask.

9. The method according to claim 1, wherein the depth of the first device separating structure ranges from about 100 to about 1500 Å.

10. The method according to claim 1, wherein the act of etching the first device separating structure is a wet-etching process with a HF or BOE solution.

11. The method according to claim 1, wherein the thickness of the SEG film ranges from about 100 to about 2000 Å.

12. The method according to claim 1, wherein the second device separating structure is formed from an oxide film.

13. The method according to claim 1, wherein the thickness of the second device separating structure ranges from about 100 to about 2000 Å.

14. The method according to claim 1, wherein the act of forming a second device separating structure includes:
forming an oxide film over the barrier film and the second active regions; and
performing a planarizing process to expose the first active regions.

15. The method according to claim 14, further comprising forming a gate structure after the planarizing process.

16. The method according to claim 15, wherein the act of forming a gate structure includes:
etching the first and second active regions at a predetermined depth to form a recess gate region;
forming a gate pattern over the recess gate region; and
forming a spacer at the sidewall of the gate pattern.

17. The method according to claim 16, wherein the act of forming a gate pattern includes forming and patterning a polysilicon layer, a gate metal layer, and a gate hard mask layer.