KR910007534B1 - Micro-pattern forming method - Google Patents

Abstract

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Description

Fine pattern formation method

1 is a process cross-sectional view showing the method of the first embodiment of the present invention.

2 is a process cross-sectional view showing the method of the second embodiment of the present invention.

3 is a process cross-sectional view showing the method of the third embodiment of the present invention.

4 is a process cross-sectional view showing the method of the fourth embodiment of the present invention.

5 is a process cross-sectional view showing the method of the fifth embodiment of the present invention.

6 is a characteristic diagram showing the relationship between the resist thickness and the irradiation amount of the PMMA resist immersed in the developer after H ⁺ ion irradiation.

7 is a characteristic diagram showing the relationship between the etching rate and the irradiation amount of SiCl ₄ , Cl ₂ gas of PMMA resist irradiated with H ⁺ ions.

* Explanation of symbols for the main parts of the drawings

1: semiconductor substrate 2: resist film,

3: H ⁺ ion 4: H ⁺ ion irradiation area,

5: electron beam 11: polymer membrane

12: PMMA resist 13: Si ⁺ ion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a micropattern using electron beam or focus ion beam lithography, and in particular, to improve dry-etch resistance of a resist by ion irradiation. It relates to a fine pattern forming method.

The micropattern forming method is divided into a lithography process and an etching process. In order to improve the dry etching resistance of the resist pattern formed in the lithography process, a phenyl radical or a silicone resin having high dry etching resistance is introduced into the resist component. It has been attempted to improve the resistance of the resist material itself to dry-etch using it, and also the dry etching resistance is increased by ion implantation after pattern formation.

On the other hand, in the lithography process, for example, baking or ammonia treatment is performed as a post-exposure treatment to form an inversion pattern, thereby obtaining a microresist pattern by this inversion method.

Therefore, until now, various considerations have been given to improve the dry-etching resistance of the resist itself, but it is necessary to reduce the film thickness of the resist in order to form a fine pattern due to an increase in resolution. When etching the substrate using a fine pattern such as a mask, the resist is nicknamed. Therefore, when the film thickness is small, it is difficult to transfer the pattern in the etching process and implant ions into the resist pattern to improve dry-etch resistance. In this case, ions are also injected into the semiconductor substrate, causing ion irradiation damage.

In addition, in the conventional reversal method, only the characteristic resist is applied, so that it has weak dry-etching resistance.

Therefore, the primary object of the present invention is to apply the ion irradiation technique before or after the exposure of the electron beam or the focus ion beam, so that the dry-etching resistance is high by using the positive resist having the low dry-etching resistance but the high resolution. A method of forming a positive-negative inversion pattern is provided.

The present invention provides various advantages as follows.

Since the ion-irradiation technique is applied after or before electron beam or focus ion beam exposure to form a positive-negative reverse pattern having high dry-etch resistance, it is possible to dry-etch the substrate with high precision using such a resist pattern as a mask. In particular, when dry-etching is performed by using a multilayer or single layer of weak but high resolution electronic resist and forming a microresist pattern, a large contribution to the fabrication of a very large integrated circuit is made.

Further objects and features of the present invention are understood and become apparent from the following detailed description, which is enumerated in the appended claims and the organization and content of the invention, in conjunction with the drawings. It will be described below with reference to FIG. 1 which is an embodiment of the present invention. Low resistance to dry as a resist on a semiconductor substrate (1) to get it to etching and 1000rpm in a PMMA having a high resolution and resist spin-coating of 0.6μm thickness and baked 20 minutes in an oven to 170 ° membrane (2) H ⁺ The ions 3 are irradiated at an acceleration voltage of 40 kv and an irradiation dose of 8 x 10 ¹³ ions / cm 2 to be soluble in the developer (Fig. 1a).

Next, an H ⁺ ion irradiation region 4 was formed by exposure to an electron beam at an acceleration voltage of 10 kev, a beam current density of 40 A / cm 2, and a dose of 5 × 10 ¹⁴ ions / cm 2 (FIG. 1b) to form a methyl isobutyl ketone (MIBK). ) And isopropyl alcohol (IPA) in a mixture to obtain a positive-negative inverted microresist pattern 4P having a resolution of 0.5 탆 (Fig. 1C). Since the resist pattern 4P is exposed at a total amount of 5.8 × 10 ¹⁴ ions / cm 2, the dry-etch resistance is improved by about three times, so that it is possible to dry-etch the substrate using such a resist pattern as a mask.

Therefore, according to this embodiment, when a single layer of electron beam resist having weak dry-etching resistance is irradiated with H ⁺ ions to form a microcellular negative-negative inversion pattern, the dry-etching resistance of such a resist pattern is improved by more than two times. The substrate is dry etched using an electron beam resist monolayer as a mask.

2 shows a second embodiment of the present invention. The polymer film 11 is formed to a thickness of 2 μm by spin coating on the semiconductor substrate 1 and baked at 200 ° C. for 2 minutes on a hot plate. A 0.5 μm-thick PMMA resist 12 was spin-coated on the polymer film 11 as a resist and baked on a hotplate at 200 ° C. for 2 minutes and irradiated with Si ⁺ ions with an irradiation voltage of 40 Kv and 8 × 10 ¹³ ions / cm 2. To be soluble in the developer (Fig. 2a). Next, when exposed to an electron beam with an acceleration voltage of 20 kev, a beam current density of 40 A / cm ² , and a dose of 5 × 10 ¹⁴ ions / cm ² (FIG. 2b) and developed in a mixture of MIBK and IPA, a predetermined positive-negative Inverted fine resist pattern 14P is obtained (FIG. 2C). Since the resist pattern is irradiated with Si ⁺ ions of 8 x 10 ¹³ ions / cm 2, the dry-etch resistance is improved by about 10 times. The use of such a resist pattern as a mask etches the polymer film in the lower layer and forms a fine resist pattern having a high aspect ratio and excellent dry-etch resistance (FIG. 2D).

6 shows the resist thickness measured after irradiating electron beam resist PMMA with H ⁺ ions at an accelerating voltage of 40 kev and immersing it in a developer. In the dosage range of 5-9 × 10 ¹³ ions / cm 2, the resist is soluble in the developer and insoluble at high dosages. FIG. 7 shows the etching ratio of resist to SiCl ₂ and Cl ₂ gases after irradiating PMMA resist with H ⁺ ions at an accelerating voltage of 40 kv and the dry-etch resistance of PMMA increases rapidly with increasing dose. Therefore, before the electron beam exposure, the resist is irradiated with ions of ^{5 to} 9 × 10 ¹³ ions / cm 2 to form a soluble resist in the developer, and when the electron beam is continuously exposed, the curved area becomes insoluble in the developer, and when developed, An etchable positive-negative inversion pattern is formed. On the other hand, if a resist is applied on the entire surface of the semiconductor substrate, the irradiation ions cannot enter the semiconductor substrate and the substrate is not damaged.

3 shows a third embodiment. The polymer film 21 is spin-coated to a thickness of 2 탆 on the semiconductor substrate 1 and baked for 2 minutes on a hot plate at 200 ° C. PMMA resist 22 as a resist on the polymer film 21 was spin-coated to a thickness of 0.5 μm and baked at 200 ° C. for 2 minutes on a hot plate, and irradiated with Si ⁺ ions having an acceleration voltage of 40 Kv and an irradiation amount of 8 × 10 ¹⁵ ions / cm 2. To be soluble in the developer (Fig. 3a). This is then exposed to a focus Si ⁺ ion beam with an acceleration voltage of 100 kev and an irradiation dose of 1 × 10 ¹⁵ ions / cm 2 (FIG. 3b), and developed in a mixture of MIBK and IPA to produce a predetermined positive-negative reverse microresist pattern 24P. Is obtained (FIG. 3C). Such a resist pattern is exposed to Si ⁺ ions of 1 × 10 ¹⁵ ions / cm 2, thereby improving dry-etching resistance by 100 times or more. Using such a resist pattern as a mask, the underlayer polymer film is etched and formed (FIG. 3D).

4 shows a fourth embodiment. The semiconductor substrate 1 is coated with a low dry-etching resistance and high resolution electron beam resist PMMA at 1000 ppm by baking, and then baked in an oven at 170 ° C. for 20 minutes to have a thickness of 0.6 μm. Get This was exposed to an electron beam with an acceleration voltage of 20 Kv, a beam current density of 40 A / cm 2 and an irradiation dose of 5 x 10 ¹⁴ ions / cm 2 (Fig. 4a), and an H ⁺ ion of an acceleration voltage of 40 Kv and an irradiation amount of 8 x 10 ¹³ ions / cm 2 ( 34) (FIG. 4B), and developing in a mixture of MIBK and IPA yields a positive-negative inverted microresist pattern 35P with a resolution of 0.5 [mu] m (FIG. 4C). Since the resist pattern 35P is exposed to a total of 5.8 × 10 ¹⁴ ions / cm 2, the dry-etch resistance is approximately three times improved. It is therefore possible to dry-etch the substrate using such a resist pattern as a mask.

Therefore, according to this embodiment, when the weak dry-etching electron beam resist monolayer is irradiated with H ⁺ ions, the dry-etch resistance is more than doubled, so that the substrate is etched using the electron beam resist monolayer as a mask.

In this embodiment, in addition to using electron beam exposure, focus ion beam exposure is similarly performed, and similar effects can be obtained with positive resists other than PMMA resists, and others are used instead of H ⁺ ions and Si ⁺ ions. do.

5 shows a fifth embodiment. On the semiconductor substrate 1, the polymer film 51 is spin-coated at a thickness of 2 탆 and baked on a hot plate at 200 ° C for 2 minutes. The PMMA resist 52 as a resist on the polymer film 51 was spin-coated to a thickness of 0.5 μm, baked for 2 minutes on a hot plate at 200 ° C., and had an acceleration energy of 100 kev, a current density of 40 A / cm 2, and an irradiation dose of 1 × 10 ¹³ ions / cm 2. Exposure to Si ⁺ focus ion beam (Figure 5a). Next, it is irradiated with Si ⁺ ions 55 having an acceleration voltage of 40kv and an irradiation amount of 8x10 ¹³ ions / cm 2 and developed in a mixture of MIBK and IPA to obtain a predetermined positive-negative reverse microresist pattern 54P (Fig. 5C). ). Since the resist pattern 54P is irradiated with Si ⁺ ions of 1 × 10 ¹⁶ ions / cm 2, the dry-etch resistance is improved by approximately 100 times. By using such a resist pattern as a mask, the underlayer polymer film is etched to form a fine resist pattern having excellent dry-etching and high aspect ratio (FIG. 5D).

As is apparent from FIG. 7, the dry-etching resistance of PMMA is dramatically improved as the dosage increases. Therefore, when irradiated with ions of ^{5 to} 9 x 10 ¹³ ions / cm 2 after exposure to electron beams or focus ion beams, the bent region is insoluble in the developer, and when developed, a high dry-etch resistant positive-negative inversion pattern is formed. In addition, since the resist is applied on the entire surface of the semiconductor substrate, irradiated ions do not enter the semiconductor substrate, thereby avoiding damage to the substrate.

Therefore, according to the present embodiment, a multilayer dry resist is also used on a semiconductor substrate having a process to irradiate a low dry-etching resist with ions to form a high aspect ratio dry-etching positive-negative inverted microresist pattern. .

While embodiments and features of the present invention have been described and described herein, variations and changes are realized by those skilled in the art, and understanding of the appended claims may compensate for all modifications and changes that fall within the scope and spirit of the invention.

Claims (8)

The micropattern forming method includes a process of coating a resist on a semiconductor substrate, a process of irradiating the entire surface of the resist with ions of one of H ⁺ and Si ⁺ and exposing the resist to an electron beam and developing the same. And forming a positive-negative inverted integrated circuit pattern to form a highly dry-etch resist pattern. The method of forming a fine pattern of claim 1, wherein a low dry-etching electron beam resist is used as the resist. The method of forming a micropattern according to claim 1, wherein the ion irradiation is performed at a low acceleration voltage of 10 to 40 Kv and an irradiation amount of 5 x 10 ¹³ to 9 x 10 ¹³ ions / cm 2. The micropattern forming method includes coating a polymer film on a semiconductor substrate, coating a resist on the polymer film, irradiating the entire surface of the resist with at least Si ⁺ ions, exposing the resist to an electron beam, and developing the same. And forming a positive-negative inverted integrated circuit pattern, and etching the polymer film using a resist pattern as a mask. The micropattern forming method includes a process of coating a polymer film on a semiconductor substrate, a process of coating a resist on the high capacitive film, and a process of collectively irradiating the entire surface of the resist with at least one ion of H ⁺ and Si ^+; Exposing and developing the resist to a focus ion beam to form a positive-negative inverting microresist pattern, and etching the polymer film using a resist pattern as a mask. The micropattern forming method includes a process of coating a resist on a semiconductor substrate, a process of exposing the resist to one of an electron beam and a focus ion beam, and an entire surface of the resist with at least one ion of H ⁺ and Si ⁺ . A method of forming a fine pattern, characterized in that to form a resist pattern having a high dry-etch resistance, including a step of collectively irradiating and developing to form a positive-negative inverted integrated circuit pattern. 7. The method of forming a micropattern according to claim 6, wherein the ion irradiation is performed at a low acceleration voltage of 10 to 40 Kv and an irradiation amount of 5 x 10 ¹³ to 9 x 10 ¹³ ions / cm 2. The micropattern forming method includes the steps of coating a polymer film on a semiconductor substrate, coating a resist on the polymer film, exposing the resist to one of an electron beam and a focus ion beam, and at least the entire surface of the resist. A micropattern comprising a step of collectively irradiating and developing one of H ⁺ and Si ⁺ to form a positive-negative inverted integrated circuit pattern, and etching the polymer film using a resist pattern as a mask Formation method.

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