KR20090066841A - Method for manufacturing pillar pattern - Google Patents

Abstract

A method for forming a pillar pattern is provided to prevent pattern collapse due to a defocus by securing sufficiently a DOF(Depth Of Focus) margin. A first photoresist layer is coated on an upper part of a semiconductor substrate(110). The first photoresist layer reacts to a first light source. A first exposure process and a first development process for the first photoresist layer are performed to form a first photoresist layer pattern. A contact hole is defined in the first photoresist layer pattern. The contact hole is filled with a second photoresist layer. The second photoresist layer reacts to a second light source having a wavelength which is different from the wavelength of the first light source. A second photoresist layer pattern of a pillar type is formed by removing the first photoresist layer pattern.

Description

Pillar pattern formation method {Method for manufacturing pillar pattern}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a semiconductor device, and more particularly, to form a pillar pattern by forming a contact hole in a photoresist film and then applying an image reversal process to sufficiently secure a DOF margin to defocus. The present invention relates to a pillar pattern forming method capable of preventing a pattern collapse due to the pattern collapse.

As the degree of integration of semiconductor devices increases, the planar area occupied by electronic devices constituting the semiconductor devices shrinks.

In particular, in the case of a planar transistor, a method of reducing the channel width of the transistor is used to increase the degree of integration of the semiconductor device. Since the channel width is proportional to the drain current, reducing the channel width may reduce the current transfer capability of the transistor. Decreases.

Therefore, the planar transistor has a structure that cannot satisfy both the improvement of the characteristics of the transistor and the increase in the degree of integration.

In order to solve this problem, a vertical transistor has been proposed. The vertical transistor is configured by forming a vertical gate on a side of a poly silicon pillar, forming a source under the cylinder, and forming a drain on the top of the cylinder.

Since the channel length of the vertical transistor is not limited by the limitations that can be formed by current lithographic equipment and exposure methods, and the channel length can be adjusted by adjusting the height of the cylinder, the vertical transistor is a flat panel type. Shorter channel lengths than transistors can be achieved.

In addition, since the vertical gate is formed on the side of the cylinder to have a larger channel width than the planar transistor, it has not only faster switching capability but also greater power driving capability.

1 is a cross-sectional view illustrating a method of forming a general pillar pattern, in which a bottom anti-reflective coating (BARC) 12 and a positive photoresist 14 are sequentially formed on a semiconductor substrate 10. And an exposure process is performed using the exposure mask 16.

After the exposure process, a development process is performed on the photoresist 14 to form a photoresist pattern having a pillar pattern defined therein.

FIG. 2A is a cross-sectional view illustrating a collapse of the photoresist pattern 14a in which a pillar pattern is defined, and FIG. 2B is a scanning electron microscope (SEM) photograph, and the pillar pattern is a depth of focus (hereinafter referred to as DOF). Because of the small size, collapsing occurs easily due to defocus.

When the photoresist pattern 14a having the pillar pattern defined there is a deadly defect in which the lower layer patterns are shorted with each other after a subsequent etching process, thereby preventing the semiconductor device from operating.

The photoresist pattern 14a in which the pillar pattern is defined is collapsed in a developing process. The main reason for the photoresist pattern 14a to fall is that the force to collapse the photoresist pattern 14a is due to the adhesive force or the photoresist between the photoresist pattern 14a and the wafer. This is because it is larger than the mechanical strength of the pattern 14a.

In the photoresist film developing process, a developer is sprayed onto a wafer to perform a developing operation, and deionized water is sprayed to stop a developing operation and a rinse operation is performed to wash the photoresist residue. Thereafter, the wafer is rotated to proceed to a drying operation in which distilled water is evaporated. Here, the photosensitive film pattern 14a falls down at a moment when the distilled water hardly evaporates and remains on the wafer in the drying step of rotating the wafer after the rinsing operation.

Also, FIG. 3 shows that the photoresist pattern 14a is degraded due to the optical proximity effect (hereinafter referred to as OPE), and thus the photoresist pattern 14a (photoresist) of the pillar pattern after the development process is reduced. This is a cross-sectional view showing the case where the thickness b is lower than the thickness a of the photosensitive film 14. The problem is that the resolution is lowered because the OPE due to diffraction in which the light source used in the exposure process penetrates in all directions is large. have.

Since the present invention forms a pillar pattern by forming a contact hole in the photoresist film and then applying an image reversal process, sufficient DOF margin can be secured to prevent pattern collapse due to defocus. An object of the present invention is to provide a pillar pattern forming method.

The pillar pattern forming method according to the present invention

Applying a first photoresist film on the semiconductor substrate, the first photosensitive film reacting with the first light source;

Forming a first photoresist pattern on which the contact hole is defined through a first exposure process and a first development process with respect to the first photoresist;

Filling the contact hole with a second photoresist film responsive to a second light source having a wavelength different from that of the first light source; And

And removing the first photoresist pattern to form a second photoresist pattern having a pillar shape.

The method may further include applying BARC on the semiconductor substrate.

Filling the contact hole

Applying the second photoresist layer on the first photoresist pattern pattern including the contact hole; And

Performing an etch back process on the second photoresist layer;

The etch back process is performed until the second photoresist film buried in the contact hole forms a vertical pillar pattern,

The etch back process is performed with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%),

Performing a second exposure process on the second photosensitive film by using the second light source;

The second exposure process is performed by a blank exposure process,

Removing the first photoresist pattern by performing a third exposure process and a second development process using the first light source with respect to the first photoresist pattern in the step of forming the second photoresist pattern,

The third exposure process is performed by a blank exposure process,

The third development process is carried out with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%),

And reducing the size of the contact hole by performing a reflow process on the first photoresist pattern.

The reflow process is performed by baking the first photoresist pattern using a hot plate,

The first development process is characterized in that it is carried out with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%).

Since the present invention forms a pillar pattern by forming a contact hole in the photoresist film and then applying an image reversal process, sufficient DOF margin can be secured to prevent pattern collapse due to defocus. It has an effect.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the spirit of the present invention is thoroughly and completely disclosed, and the spirit of the present invention to those skilled in the art will be fully delivered. Also, like reference numerals denote like elements throughout the specification.

4A to 4F are cross-sectional views illustrating a method of forming a pillar pattern according to the present invention.

Referring to FIG. 4A, a BARC (Bottom Anti-Reflective Coating) 112 is coated on the semiconductor substrate 110 at a thickness of 280 kPa and then heated at 240 ° C. for 90 seconds.

Subsequently, a positive ArF photoresist film was applied to a thickness of 1200 Å and then baked at 115 ° C. for 90 seconds.

After the exposure process was performed on the ArF photoresist with an exposure mask using an exposure apparatus, a contact hole having a size of 70 nm was contacted with a solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%) for 20 seconds. hole) 115 defines a defined ArF photoresist pattern 114.

Referring to FIG. 4B, a reflow process is performed on the ArF photoresist pattern 114 by baking at 150 ° C. for 90 seconds using a hot plate. At this time, the size of the contact hole 115a defined in the reflowed ArF photoresist pattern 114a is reduced from 70 nm to 40 nm.

Referring to FIG. 4C, a positive i-line photoresist 116 is applied on the ArF photoresist pattern 114a including the contact hole 115a defined in the ArF photoresist pattern 114a to a thickness of 2000 microseconds. And it bakes at 90 degreeC for 90 second.

Referring to FIG. 2D, the eye line photoresist 116 is etched back with an aqueous TMAH solution (2.38%). At this time, the etch back process is performed until the eye line photoresist 116 having the contact hole 115a defined in the ArF photoresist pattern 114a becomes a vertical pillar pattern. In addition, when the etch back is performed after a blank exposure is performed on the eye line photosensitive layer 116 with an i-line, the etch back speed may be improved.

Referring to FIG. 4E, a blank exposure is performed on ArF photoresist pattern 114a with ArF. At this time, the exposure energy is sufficiently irradiated so that the ArF photosensitive film 114a can be completely removed during development.

Referring to FIG. 4F, the ArF photoresist pattern 114a is developed by TMAH aqueous solution (2.38%) and completely removed. At this time, the ArF photoresist pattern 114a may be completely removed since the ArF photoresist pattern 114a is subjected to a blank exposure with sufficient exposure energy. Therefore, only the eye line photoresist pattern 116a, which is filled in the contact hole 115a and forms a pillar pattern, remains.

Here, since the pillar pattern 116a is formed using the eye line photoresist 116, the etching resistance is better than that of the ArF photoresist pattern 114a, and CD uniformity is easily controlled when the lower layer is etched. can improve the uniformity.

In addition, the contact hole 115 is formed using the ArF photosensitive film pattern 114a having a small POE, and then the pillar pattern 116a is finally formed using an image reversal process using the eye line photosensitive film 116. Therefore, the photoresist film thickness loss of the pillar pattern 116a is relatively small. Therefore, when etching the lower layer (for example, Oxide, Nitride, Aluminum, etc.) it is easy to control the CD of the lower layer can improve the CD uniformity.

In the above-described embodiment of the present invention, the case where the positive ArF photosensitive film 114 is used to form the contact hole 115 has been described as an example, but is not limited thereto. That is, a negative ArF photosensitive film can be used.

In addition, the embodiment of the present invention has been described using the ArF photosensitive film 114 and the i-line photosensitive film 116 as an example, but is not limited thereto. That is, the pillar pattern forming method of the present invention can be applied to the case of using two photosensitive films reacting to different light sources. That is, it is also applicable to the case of using a photosensitive film such as KrF, EUV.

In the pillar pattern forming method of the present invention, when forming the pillar pattern having the same size, when the pillar hole is formed by forming the contact hole and then applying the image reversal process to form the pillar pattern rather than directly forming the pillar pattern, the defocus is large. Pattern collapse due to (defocus) can be prevented.

In addition, a preferred embodiment of the present invention is for the purpose of illustration, those skilled in the art will be able to various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, such modifications and changes are the following claims It should be seen as belonging to a range.

1 is a cross-sectional view illustrating a method of forming a general pillar pattern.

FIG. 2A is a cross-sectional view illustrating a collapse of the photoresist pattern 14a in which a pillar pattern is defined, and FIG. 2B is a scanning electron microscope (SEM) photograph.

3 shows that the photoresist pattern 14a is degraded by OPE so that the thickness b of the photoresist pattern 14a of the pillar pattern is lower than the thickness a of the photoresist 14 after the development process. It is sectional drawing which shows the case.

4A to 4F are cross-sectional views illustrating a method of forming a pillar pattern according to the present invention.

<Description of the symbols for the main parts of the drawings>

110: semiconductor substrate 112: BARC

114, 114a: ArF photosensitive film pattern 115, 115a: contact hole

116: eye line photosensitive film 116a: eye line photosensitive film pattern

Claims (13)

Applying a first photoresist film on the semiconductor substrate, the first photosensitive film reacting with the first light source; Forming a first photoresist pattern on which the contact hole is defined through a first exposure process and a first development process with respect to the first photoresist; Filling the contact hole with a second photoresist film responsive to a second light source having a wavelength different from that of the first light source; And And removing the first photoresist pattern to form a second photoresist pattern having a pillar shape. The method of claim 1, The method of claim 1, further comprising applying a BARC on the semiconductor substrate. The method of claim 1, Filling the contact hole Applying the second photoresist layer on the first photoresist pattern pattern including the contact hole; And And performing an etch back process on the second photoresist film. The method of claim 3, wherein The etch back process may be performed until the second photoresist film buried in the contact hole forms a vertical pillar pattern. The method of claim 3, wherein The etchback process is a pillar pattern forming method, characterized in that carried out with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%). The method of claim 3, wherein And performing a second exposure process on the second photosensitive film using the second light source. The method of claim 6, The second exposure process is a pillar pattern forming method, characterized in that performed by a blank exposure process. The method of claim 1, Forming the second photoresist pattern to remove the first photoresist pattern by performing a third exposure process and a second development process using the first light source with respect to the first photoresist pattern; Forming method. The method of claim 8, The third exposure process is a pillar pattern forming method, characterized in that performed by a blank exposure process. The method of claim 8, The third development process is a pillar pattern forming method, characterized in that carried out with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%). The method of claim 1, And reducing a size of the contact hole by performing a reflow process on the first photoresist pattern. The method of claim 11, The reflow process may be performed by heating the first photoresist pattern by using a hot plate. The method of claim 1, The first development process is a pillar pattern forming method, characterized in that carried out with an aqueous solution of Tetra-Methyl Ammonium Hydroxide (TMAH) (2.38%).

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