KR20000051049A - Method for flowering photoresist and manufacturing method of mask substrate using the same - Google Patents

Abstract

PURPOSE: A fabrication method of a mask substrate and a photoresist flow method are provided to enable the formation of various pattern layouts without using different mask substrates. CONSTITUTION: A mask substrate(10) includes a chromium layer(15b) having various pattern parts with different thickness formed by several photolithography processes. A first part(B) where the mask substrate(10) is entirely exposed transmits an exposure light(55) at almost 100 percents, a second part(A) where the chromium layer(15b) is thinly formed partially transmits the exposure light(55) in inverse proportion to the thickness of the chromium layer(15b), and a third part(C) where the chromium layer(15b) is thickly formed hardly transmits the exposure light(55). Therefore, respective parts of a photoresist pattern(65) formed on a semiconductor substrate(60) are exposed in a different energy, and then flowed at a different rate in a single thermal process.

Description

Photoresist flow method and mask substrate manufacturing method used therein {Method for flowering photoresist and manufacturing method of mask substrate using the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a mask substrate used in a photoresist flow process and a method of performing a photoresist flow process using such a mask substrate. By varying the thickness of the mask substrate, a method of manufacturing a mask substrate capable of locally varying the transmittance of the exposure during the exposure process and a flow process of the photoresist pattern applied on the semiconductor substrate using the substrate may be performed. The present invention relates to a photoresist flow method capable of allowing a photoresist flow to proceed.

Among the fine patterns of semiconductors, in particular, a method for forming a contact hole smaller than an exposure wavelength is used in the current process, a thermal flow method using thermal flow characteristics of a photoresist. However, when the minute contact patterns are disposed on the semiconductor layout, various pattern sizes may not be obtained unless the thermal flow amount of the photoresist is locally controlled due to the characteristics of the semiconductor device.

In order to solve such a problem, a conventional method being used, after forming a contact pattern by exposure, prior to performing the thermal flow process of the photoresist, using a mask substrate to selectively adjust a region for thermal flow amount to be selectively When exposed to ultraviolet light (UV) or more than the dose, or irradiated with an electron beam (E-beam) or an ion beam (Ion-beam), it proceeds by using a property that changes the chemical properties of the resin constituting the photoresist. In this way, when the thermal flow process of the photoresist is performed, a difference in the thermal flow amount of the photoresist occurs in a portion pre-treated with the photoresist as described above and a portion that is not, thereby obtaining a desired pattern size.

However, such a conventional method may cause a problem that a desired pattern size cannot be obtained unless the thermal flow amount is different for each region by dividing the layout into several regions due to the layout characteristics of the semiconductor device.

The technical problem to be achieved by the present invention is to solve the cumbersome problem of differently forming a mask substrate for each region according to the layout of the upper semiconductor substrate in order to form a photoresist pattern of various sizes on the same semiconductor substrate, It is an object of the present invention to provide a mask substrate that can be used in an exposure process that can achieve such a technical problem and a photoresist flow method using the mask substrate.

1 is a graph for explaining the relationship between deposition time and light transmittance during formation of a chromium layer, which is an index of the thickness of a chromium layer formed on a mask substrate.

2 to 10 are cross-sectional views illustrating a method of manufacturing a mask substrate used in the photoresist flow method according to the present invention.

11 to 12 are cross-sectional views illustrating a photoresist flow method according to the present invention.

The photoresist flow method for achieving the above-described technical problem is to form a pattern on the photoresist applied on the semiconductor substrate; Irradiating the photoresist pattern with a predetermined light source or a predetermined beam through a mask substrate having a locally varying light transmittance in order to change the chemical properties of the resin of the photoresist pattern; And performing a thermal flow process on the photoresist pattern.

In this case, it is preferable that the mask substrate has a different light transmittance locally due to a difference in the thickness of the light shielding film pattern formed on the substrate. On the other hand, the light shielding film pattern is preferably formed of a material containing chromium.

The mask substrate manufacturing method used for the photoresist flow method for achieving the technical problem which this invention mentioned above is made in the method of manufacturing the exposure mask substrate which differs in thickness, changing a region on the same mask substrate upper part, (A) sequentially applying a light blocking material film and a photoresist film having a predetermined thickness on the mask substrate, and then irradiating an electron beam to a predetermined area on the photoresist film; (B) developing a predetermined portion of the photoresist film irradiated with the electron beam to expose the light blocking material film; (C) etching a predetermined thickness of the exposed light blocking material film to form a light blocking film pattern; (D) removing the photoresist film to expose the light shielding film pattern; And (e) varying the etching thickness of the step (c) with respect to the upper part of the mask substrate in the area different from the upper area of the mask substrate in which the steps (a) to (d) are performed. It is characterized in that it comprises a;) repeating the step;

In this case, it is preferable to use one of materials selected from chromium, MoSiON, CrON, and WSi as the light shielding material on the mask substrate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art related to the present invention. In the drawings, the thicknesses of layers or regions are exaggerated for clarity. In the drawings like reference numerals refer to like elements. In addition, where a layer is described as being "on top" of another layer or substrate, the layer may be present directly on top of the other layer or substrate, with a third layer intervening therebetween.

1 to 12 are views for explaining the present invention in detail, will be described below by dividing the respective drawings for an embodiment according to the present invention.

1 is a graph for explaining the relationship between deposition time and light transmittance during chromium layer formation, which is an index of the thickness of the chromium layer formed on the mask substrate. According to the graph of FIG. 1, the vertical axis represents the light transmittance (%) passing through the mask substrate, and the horizontal axis represents the thickness of the chromium layer formed for use as a light shielding film on the mask substrate as the time (seconds) for depositing the chromium layer. In conversion, it is shown. That is, since the deposition time of the chromium layer is in proportion to the thickness of the chromium layer, the horizontal axis may be set to the deposition time of the chromium layer. Lines connected in a square in the gap of FIG. 1 indicate transmittance with respect to the thickness of the chromium layer in the case of using the I-line, and lines connected in the rhombus are the same as in the case of using the ultraviolet ray, and light transmittance is the type of the exposure source. It can be seen that it is inversely proportional to the thickness of the chromium layer. Using this principle, it is important to control the degree of flow of a subsequent photoresist flow process by forming a light shielding film with a chromium layer having a different thickness on the same mask substrate, and locally varying the transmittance of exposure. It is one of the matters.

2 to 10 are cross-sectional views illustrating a method of manufacturing a mask substrate used in the photoresist flow method according to the present invention.

First, FIG. 2 to FIG. 6 will be described in detail. A chromium layer 15, which is a light shielding material, is coated on the mask substrate 10, which is mainly made of quartz, and an electron beam photoresist layer 20 is applied thereon, and then an electron beam is applied to a predetermined portion. Is irradiated 25 to locally denature the photoresist layer 20 (FIG. 2). The development process of the locally modified photoresist layer in FIG. 2 is performed to form a first photoresist pattern 20a exposing a predetermined portion of the chromium layer 15 (through “30”) ( 3). The exposed chromium layer (15 in FIG. 2) is continuously etched to form a primary chromium layer pattern 15a exposing (through "30a") the underlying mask substrate 10 (FIG. 4). . After the process of removing the primary photoresist pattern (“20a” of FIG. 4), the mask substrate 10 under the primary chromium layer pattern 15a is exposed through the reference numeral “30b”. (FIG. 5). According to FIG. 6, an electron beam photoresist layer 35 is again applied to the entire surface of the resultant product of FIG. 5 (FIG. 6).

Next, FIG. 7 to FIG. 10 will be described in detail, which is similar to the progress of the process of FIG. 2 to FIG. 5. However, the electron beam is irradiated in a region different from the electron beam irradiation region of FIG. 2 (40), and the patterning process for the chromium layer is performed. During the patterning process, only a partial thickness of the chromium layer is etched to provide a mask substrate ( 10) The difference is that the remaining thickness of the chromium layer to remain on top. After irradiating an electron beam to a predetermined region of the mask substrate (FIG. 7), a second photoresist pattern 35a is formed (FIG. 8). In order to show a difference from the foregoing process, the second photoresist pattern 35a exposes the first chromium layer pattern 15a through reference numeral 45a (FIG. 8), and then, by performing an etching process, The secondary chrome layer pattern 15b is exposed through reference numeral 45b (FIG. 9). When the photoresist layer remaining on the mask substrate is removed, a mask substrate 10 having a chromium layer pattern 15b of locally varying thickness is formed (FIG. 10).

11 to 12 are cross-sectional views illustrating a photoresist flow method according to the present invention.

FIG. 11 is a cross-sectional view illustrating a process of exposing a photoresist patterned on a semiconductor substrate using a mask substrate manufactured by the description of FIGS. 2 to 10. A chromium layer pattern 15b is formed on the same mask substrate 10 and is formed while varying its thickness, which is coated for light shielding. According to the principle illustrated in FIG. 1, almost 100% transmittance is expected in the region B where the chromium layer is completely removed and the lower mask substrate 10 is exposed through the reference numeral 50. In the region A in which the layer remains on the mask substrate 10, a transmittance of exposure inversely proportional to the thickness is expected. On the other hand, in the region C where the chromium layer is formed sufficiently thick, the transmittance is expected to be almost 0%. The exposure energy 55 transmitted through the mask substrate 10 reaches the photoresist pattern 65 coated on the semiconductor substrate 60 and passes through the photoresist pattern 65 at different regions in each region. The degree of denaturation of (65) will vary. This is because the crosslinking reaction of the resin inside the photoresist pattern 65 on the semiconductor substrate 60 proceeds in proportion to the transferred energy as the exposure energy passes through the mask substrate and locally different amounts of energy are transferred. Different thermal flows may be performed for each photoresist pattern formed while changing regions on a single semiconductor substrate.

Referring to FIG. 12, when the thermal flow process under the same conditions is performed on the photoresist pattern regions having different crosslinking reactions, that is, denaturation levels of the resins by exposures having different transmittances for each region according to FIG. As the flow rate of the photoresist appears differently, the width of the upper surface of the semiconductor substrate actually exposed by the photoresist pattern is changed. That is, in the region where the transmittance reaches almost 100% (" B " in Fig. 11), the hardening of the photoresist occurs so that the thermal flow occurs less, so that the width E that exposes the semiconductor substrate is the largest and the exposure The slow of the hole 71 is formed almost vertically. On the contrary, in the region where the transmittance is almost 0% ("C" in FIG. 11), hardening of the photoresist hardly occurs, so that the thermal flow proceeds a lot. Therefore, the region in which the transmittance is 100% in FIG. 11 ("B" in FIG. In contrast to), the exposure width F is the smallest, and the slowness of the exposure hole 72 is formed smoothly. On the other hand, in the region of medium transmittance ("A" in FIG. 11), the exposure width D is also medium compared to the other exposure widths E and F, and the slowness of the exposure hole 70 is also different. The exposure holes 70 and 71 are in the middle. In order to specify the photoresist pattern subjected to the thermal flow process, the reference numeral is shown as "65a".

Embodiments of the present invention described with reference to the accompanying drawings are optimal embodiments. Although specific terms have been used herein, they are used only for the purpose of describing the present invention in detail and are not used to limit the scope of the present invention as defined in the meaning or claims.

According to the present invention, it is possible to avoid the trouble of performing different levels of photoresist flow processes using each mask substrate according to various types of pattern layouts to be formed on the semiconductor substrate. That is, even if the same thermal flow process is performed on a single semiconductor substrate, since the chromium layer formed on the mask substrate used in the previous step is varied, the exposure energy reaching the photoresist pattern is varied. Even in the case of the photoresist pattern formed on the top, a photoresist pattern having different degrees of flow in a single heat treatment process may be formed.

Claims (5)

Forming a pattern on the photoresist applied on the semiconductor substrate; Irradiating the photoresist pattern with a predetermined light source or a predetermined beam through a mask substrate having a locally varying light transmittance in order to change the chemical properties of the resin of the photoresist pattern; And Photoresist flow method comprising the step of performing a thermal flow process for the photoresist pattern. The method of claim 1, The mask substrate is a photoresist flow method, characterized in that the light transmittance is locally different due to the difference in the thickness of the light shielding film pattern formed on the substrate. The method of claim 2, The light blocking layer pattern is formed of a material containing chromium. In the method of manufacturing an exposure mask substrate having a different thickness while varying the region on the same mask substrate, (A) sequentially applying a light blocking material film and a photoresist film having a predetermined thickness on the mask substrate, and then irradiating an electron beam to a predetermined area on the photoresist film; (B) developing a predetermined portion of the photoresist film irradiated with the electron beam to expose the light blocking material film; (C) etching a predetermined thickness of the exposed light blocking material film to form a light blocking film pattern; (D) removing the photoresist film to expose the light shielding film pattern; And (E) Steps (a) to (d) while varying the etching thickness of the step (c) with respect to the upper portion of the mask substrate where the steps (a) to (d) are performed and the upper portion of the mask substrate in a different region. A method of manufacturing a mask substrate for use in a photoresist flow process comprising the steps of: repeating the steps. The method of claim 4, wherein The light shielding film material on the mask substrate is a mask substrate manufacturing method used in the photoresist flow process, characterized in that one of the material selected from chromium, MoSiON, CrON and WSi is used.