Method of forming pattern of semiconductor device

The priority of Korean patent application number 10-2007-0046693, filed on May 14, 2007, the disclosure of which is incorporated by reference in its entirety, is claimed.

The invention relates generally to a method of forming a pattern of a semiconductor device and, more specifically, to a method of forming a pattern of a semiconductor device which comprises forming a relatively small pattern in comparison with conventional resolution by a double patterning method using an ion implanting process.

Conventional double patterning is typically carried out by one of two methods.

The first method includes twice forming a line/space pattern with a line/space ratio of 1:3, which has a double (2:1) pitch. Since overlay affects the critical dimension (CD) in the first method, it is necessary to accurately regulate overlay in order to secure desirable CD uniformity.

The second method includes forming a line/space pattern with a line/space ratio of 1:3, forming a spacer at a sidewall of the line pattern, and forming a desired pattern using the spacer as a hard mask. Alternatively, the second method includes forming a line/space pattern with a line/space ratio of 1:3, forming a spacer at a sidewall of the line pattern, depositing another material over the spacer, and removing the spacer to obtain a desired pattern. CD regulation is also affected by overlay in this method; when the spacer is not vertical, the etched profile is inferior.

Various embodiments of the invention are directed at providing a method of forming a pattern of a semiconductor device which comprises forming a relatively small pattern in comparison with conventional resolution by a double patterning method using an ion implanting process.

According to one embodiment of the invention, a method of forming a pattern of a semiconductor device comprises: forming a first hard mask film, a first resist film, and a second hard mask film over an underlying layer of a semiconductor substrate; forming a second resist pattern over the second hard mask film; etching the second hard mask film using the second resist pattern as an etching mask to form a second hard mask pattern; performing an ion-implanting process on the first resist film with the second hard mask pattern as an ion implanting mask to form an ion implanting layer in a portion of the first resist film; and selectively etching the first resist film with the second hard mask pattern and an ion implanting layer as an etching mask to form a first resist pattern.

The ion-implanting process is performed by slant ion-implanting process.

The first hard mask film preferably comprises a polysilicon film or a nitride film.

The second hard mask film preferably comprises an oxide film or a nitride film.

The second hard mask film preferably has a thickness ranging from 0.02 μm to 0.2 μm.

The second resist pattern preferably has a ratio of line pattern to space pattern of 1 to 3.

The ion implanting process is preferably performed with an ion implanting source including phosphorus or boron with an implanting amount ranging from 1e 10 to 1e 18 and energy ranging from 8 KeV to 40 KeV.

The ion implanting process is preferably controlled by changing at least one of an implanting frequency and an implanting angle.

The pitch between the first resist pattern and the second resist pattern is one-half of the pitch between the second resist patterns.

The first resist pattern is preferably formed by selectively etching the first resist film with an O 2 plasma.

The underlying layer preferably comprises a metal film or an interlayer insulating film.

FIGS. 1 a through 1 g are cross-sectional diagrams illustrating a method of forming a pattern of a semiconductor device according to an embodiment of the invention.

FIGS. 1 a through 1 g are cross-sectional diagrams illustrating a method of forming a pattern of a semiconductor device according to an embodiment of the invention.

Referring to FIG. 1 a , a film, preferably a polysilicon film or a nitride film, is deposited over an underlying layer (not shown) of a semiconductor substrate 10 to form a first hard mask film 12 . The underlying layer preferably comprises a metal film or an interlayer insulating film.

Referring to FIG. 1 b , an i-line resist composition, illustratively having a 365 nm wavelength, is coated over the first hard mask film 12 to form a first resist film 14 .

A film, preferably an oxide film or a nitride film, is deposited over the first resist film 14 to form a second hard mask film 16 .

The thickness of the second hard mask film 16 is determined in consideration of a subsequent ion implanting process. The thickness of the second hard mask film 16 preferably ranges from 0.02 μm to 0.2 μm. An ion implanting angle and/or implanting frequency can be regulated in the subsequent ion implanting process so that the distribution of ions can be controlled.

Referring to FIG. 1 c , a resist composition, illustratively an ArF resist composition having a 193 nm wavelength, is coated over the second hard mask film 16 to form a second resist film (not shown). A suitable process, preferably a photo etching process, is performed with an exposure mask (not shown) to selectively etch the second resist film, thereby obtaining a second resist pattern 18 preferably including a line pattern and a space pattern preferably with a line/space ratio of 1:3.

Referring to FIG. 1 d , the second hard mask film 16 is etched with the second resist pattern 18 as an etching mask to form a second hard mask pattern 16 a including a line pattern and a space pattern preferably with a line/space ratio of 1:3.

The residual second resist pattern 18 is preferably removed with an O 2 plasma.

Referring to FIG. 1 e , a slope ion implanting process is performed on the first resist film 14 with a selected angle using the second hard mask pattern 16 a as an ion implanting mask to harden a part of the first resist film 14 , thereby forming an ion implanting layer 20 in a portion of the first resist film 14 . The implanted ion is preferably phosphorous or boron.

The first resist film 14 adjacent to the second hard mask pattern 16 a is masked by the second hard mask pattern 16 a so that the ion implantation in the regions to each of side the ion implanting layer 20 is minimized.

The ion implanting process is performed with an ion implanting source, preferably comprising phosphorus or boron, and preferably having an implanting amount ranging from 1e 10 to 1e 18 at an energy ranging from 8 KeV to 40 KeV. The ion is implanted in an amount sufficient that the ion implanting layer 20 is not removed in the etching process with the O 2 plasma or other suitable treatment.

The ion implanting process may be conveniently controlled by changing the implanting frequency or the ion implanting angle to regulate the ion distribution in the ion implanting layer 20 .

For example, the ion implanting angle may be changed by 180° to the initial angle so that the distribution of the ion may be focused in the center.

In the ion implanting process, the second hard mask film 16 preferably has a thickness ranging from 0.02 μm to 0.2 μm so that the ion implanting angle and the ion implanting distribution can be regulated.

Referring to FIG. 1 f , the first resist film 14 is removed, preferably with O 2 plasma using the second hard mask pattern 16 a and the ion implanting layer 20 as an etching mask. Since the ion implanting layer 20 is not affected by the O 2 plasma, a first resist pattern 14 a having a line type is formed.

When the pitch between the second resist patterns 18 ( FIG. 1 c ) is designated “A”, the pitch between the first resist pattern 14 a and the second resist patterns 18 is preferably A/2 according to the invention.

The residual second hard mask pattern 16 a and first resist pattern 14 a are then removed, preferably with the O 2 plasma.

Referring to FIG. 1 g , the first hard mask film 12 is etched with the ion implanting layer 20 as an etching mask so that a pitch between the resulting first hard mask patterns 12 a is preferably A/2.

The underlying layer (not shown) of the semiconductor substrate is selectively etched with the first hard mask pattern 12 a as an etching mask, thereby obtaining, for example, a metal pattern or an interlayer insulating pattern with a reduced pitch, preferably A/2.

Thus, it is possible to reduce the size of the pattern when an underlying interlayer insulating film is patterned or a metal pattern is formed, for example.

As described above, according to an embodiment of the invention, a method of forming a pattern of a semiconductor device can prevent non-uniformity of CD due to overlays in a double patterning method for forming a pattern, and remove defects of profiles when a spacer is not vertical. As a result, it is possible to form a fine pattern having a resolution size smaller than that of a conventional resolution.

The described embodiments of the invention are illustrative and not limiting. 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 invention may be implemented in a dynamic random access memory (DRAM) device or non volatile 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.