JPH0727221B2 - Pattern formation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fine pattern forming method in semiconductor manufacturing or the like.

[Conventional technology]

The degree of integration of semiconductor integrated circuits has improved along with the miniaturization of circuit patterns, and nowadays, pattern formation technology in the micron to submicron region is required. Several methods have been conventionally proposed as pattern forming methods in the submicron region, but there are very few techniques that can be put to practical use. The reason for this is that, in practice, it is necessary to satisfy not only high resolution and high accuracy of the pattern but also high speed of the pattern formation speed, and it is not allowed to go through a too complicated process.

Conventionally, a multi-layer resist method (for example, US Patent No.
4244799). Here, the most basic three-layer resist as a multilayer resist method will be described.

FIG. 3 shows a pattern forming process using a three-layer resist. 1 is an energy ray such as light, electron beam, ion, or X-ray. 2 is a resist sensitive to the energy rays 1 (generally called an upper layer resist), 3 is an intermediate layer, and 4 is a lower layer resist. Since the intermediate layer 3 serves as a mask when etching the lower layer resist, a material having high etching resistance, for example, spin-on glass or silicone resin is used. Reference numeral 5 is a substrate. When the upper layer resist 2 is irradiated with the energy ray 1, the upper layer resist is decomposed to generate a low molecular weight polymer. When this is dipped in a developing solution, the irradiated region is dissolved and a pattern is formed on the upper layer resist 2. The sample was placed in a reactive ion etching system and CF ₄
When etching is performed in a gas atmosphere using the upper layer resist 2 as a mask, the upper layer resist pattern is transferred to the intermediate layer 3. Further, when the intermediate layer 3 is used as a mask and etching is performed in an O ₂ gas atmosphere using a reactive ion etching apparatus, the pattern of the intermediate layer 3 is transferred to the lower layer resist 4.

[Problems to be solved by the invention]

The above method is superior to the single-layer resist method currently used in the production line in terms of covering the steps of the substrate, etching resistance of the substrate processing, resolution, etc. Since different dry etching has to be performed twice, the process is complicated. In addition, it is known that the resolution and dimensional accuracy of the pattern that is generally formed are improved as the upper layer resist becomes thinner, but in practice it is not possible to make it as thin as 0.3 to 0.5 μm because of dry etching resistance to the intermediate layer. There was a flaw. Further, since etching of the upper layer resist progresses while the intermediate layer is being etched using the upper layer resist pattern as a mask, there is a drawback that it is considerably difficult to maintain the dimensional accuracy of the pattern. Also, the intermediate layer 3
Serves as a mask for the lower layer resist 4, and therefore contains atoms (for example, Si, Ge, Mo, etc.) having a higher density than the atoms (for example, C, H, O, etc.) that normally constitute the resist. Therefore, when an electron beam is used as the energy ray, there is a problem that the electrons backscattered by the intermediate layer deteriorate the resolution of the upper layer resist.

An object of the present invention is to achieve simplification of the pattern forming process, improvement of pattern resolution and pattern accuracy.

[Means for Solving the Problems] The present invention is one or more kinds containing at least one fluorine compound on a substrate in pattern formation using energy rays such as light, electron beams, ions or X-rays. The step of sequentially laminating the materials described above, a step of irradiating at least one layer of the laminated material with an energy ray to form a pattern, and a low adhesiveness to the fluorine compound selectively inside or outside the pattern. The method is characterized by including a step of adhering the adhesive material and a step of processing the laminated material using the adhesive material as a mask.

As the fluorine compound, a fluorine-containing polymer such as polyhexafluorobutyl methacrylate, poly 1,1 dimethyl 2,2,3,3 tetrafluoropropyl methacrylate, or a hexafluorobutyl methacrylate / glycidyl methacrylate copolymer is used. Is desirable.

Further, it is desirable to use a silicon compound as the above-mentioned adhesive material.

〔Example〕

The present invention utilizes the experimental fact that the fluorine compound having a low surface energy and the silicon-based resin are remarkably lacking in adhesion.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In these figures, the same components as those shown in FIG. 3 are designated by the same reference numerals.

One embodiment of the present invention is shown in FIG. AZ1350J (manufactured by Shipley) as the lower layer resist 4 on the silicon substrate 5 has a film thickness of 1.5.
It was spin coated at a thickness of μm and baked at 200 ° C. for 30 minutes. Hexafluorobutyl methacrylate and glycidyl methacrylate copolymer as fluorine-containing polymer 6 was added to the sample (this material is disclosed in Reference 1 under the name of FBM-G).
Was spin coated at 0.1 μm and baked at 140 ° C. for 30 minutes. This was irradiated with an electron beam as energy ray 1 to form a latent image of the pattern. (See FIG. 1 (a)) FBM-G is known to exhibit high sensitivity to electron beams and X-rays. In this embodiment, a pattern was formed using an electron beam of 30 KV with an irradiation dose of ³ μC / cm ² . When this is immersed in a developing solution with a mixing ratio of ethanol and isobutyl alcohol of 1: 1 for 60 seconds,
The FBM-G in the part irradiated with the electron beam was dissolved and a pattern was formed. (See Fig. 1 (b)) Lower layer resist 4AZ135
At 0J, the electron beam sensitivity was extremely low at a few hundred μC / cm ^2, and due to the effect of hard baking, the underlying resist of the FBM-G opening remained unchanged. Next, the sample is placed on a spin coater and rotated at high speed (3000 rpm to 6000 rpm) to remove the adhesive material 7.
Then, a silicone resin was dropped. By this operation, as shown in FIG. 1 (C), the silicon resin adhered only to the opening of the FBM-G, that is, outside the pattern formed on the fluorine-containing polymer 6, and did not adhere to the upper surface of the FBM-G at all. This is because the wettability and adhesion between the silicone resin and FBM-G are significantly inferior to those of the silicone resin and AZ1350J. Such a phenomenon is caused by fluorine-containing organic polymers such as poly 1,1 dimethyl 2,2,3,3 tetrafluoropropyl methacrylate (FPM; see Ref. 2), polyhexafluorobutyl methacrylate (FBM; see Ref. 3) and Teflon. And what happens between the silicone resin and the silicone resin. The silicon resin had a thickness of about 0.1 μm and was deposited in the opening of the FBM-G. The sample is dried and then reactive ion etching equipment (RIE)
With O ₂ gas at a flow rate of 50 sccm, a power density of 0.3 W
Etching was performed for about 12 minutes under the condition of / cm ² . By this operation, as shown in FIG. 1 (d), a pattern complementary to the original pattern was formed on the substrate 5. During etching, the resist pattern formed with almost no etching of the silicon resin reflected the upper layer resist pattern very well, and it was possible to form a pattern with high dimensional accuracy.

In this embodiment, the electron beam is used as the energy ray, but the pattern can be formed by the completely same process by using the X-ray or the ion beam. Further, even if a fluorine-containing resist sensitive to light is used, the pattern can be formed by the same process. It is also possible to apply a fluorine-containing polymer layer to a substrate, form a pattern on the polymer and then apply a silicon resin to directly form a silicon resin pattern on the substrate, and mask the silicon resin to process the substrate. is there.

A second embodiment is shown in FIG. AZ1350J is applied as a lower layer resist 4 on a silicon substrate 5 by spin coating at a thickness of 1.5 μm and the temperature is 200 ° C.
I baked it for 30 minutes. FBM was added as a fluorine-containing resist 6 by spin coating to a thickness of 0.1 μm, and it was coated at 140 ° C for 30
Bake for a minute. On top of this, as the upper layer resist 2,
AZ1350J was spin-coated at a thickness of 0.1 μm and baked at 90 ° C. for 30 minutes. The sample was exposed at 60 mJ / cm ² using a g-line (wavelength 436 mm) stepper and exposed to a developing solution (MF2412: H ₂ O = 1: 1) at about 6
It was dipped for 0 seconds to form a pattern. Since the FBM resist 6 is not sensitive to light, the pattern is formed only on the upper layer resist as shown in FIG. 2 (b). The silicone resin used in the above-mentioned examples was applied to this as the adhesive material 7 by the above-described procedure by spin coating. As a result, as shown in FIG. 2 (c), no silicon resin was deposited in the pattern opening where the surface of the FBM resist was exposed, and the upper surface of AZ1350J of the upper layer resist 2,
That is, 0.2 is only present in the pattern formed on the upper layer resist 2.
About μm was deposited. When the sample was etched by RIE under the above-mentioned conditions, the same resist pattern as the original pattern as shown in FIG. 2D could be formed on the substrate 5.

In this example, the pattern formation by photoexposure was shown, but the upper layer resist was an electron beam resist such as polymethylmethacrylate (PMMA), a copolymer of phenylmethacrylate and methacrylic acid (φ-MAC), chloromethylation. It is obvious that polystyrene (CMS) or the like, or an X-ray resist can be applied to those energy rays. Further, according to the gist of the present invention, not only the positive resist as shown in FIG. 2 but also the negative resist is used as the upper layer resist, and the effect is not changed at all. Also,
The reverse process of using silicon resin as the upper layer resist and applying the fluorine-containing polymer after forming the pattern may be used. Furthermore, AZ1350J resist was used as the lower layer material throughout the first and second examples, but the present invention is not limited to this. The role of the lower layer material is to the utmost, as long as it can transfer the pattern formed in the upper layer and can withstand substrate processing, its selection range is wide. As an example, it is clear that the use of a resist such as CMS, φ-MAC, OFPR800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) or a polyimide film carbon film does not impair the effects of the present invention. Further, in this embodiment, the electric furnace was used for solidifying and drying the resist, but it is also possible to use a publicly known hot plate or microwave heater. Further, although an example of spin coating is shown as a method of applying the adhesive material, various other methods such as spray coating and dip coating can be used.

(References: 1) H. Asakawa et al, Sympo.on VLSI Technol., P88 (1982)
Oiso, Japan (Reference: 2) M. Kakuchi et al, J. Electrochem. Soc., 124, P. 1648 (197
7) (Reference: 3) K. Murase et al. Proc. Int. Conf. Microlithography, P261
(1977) Paris, France [Advantages of the Invention] As described above, in the present invention, there is no step of etching the intermediate layer using the upper layer resist as a mask unlike the conventional three-layer resist method, and a material containing a fluorine compound is laminated. If so, the mask pattern can be selectively formed by simply spin-coating the adhesive material having low adhesion to the fluorine compound after the upper layer pattern is formed, which simplifies the process and improves the pattern formation speed. improves. Further, since it is not necessary to etch the intermediate layer, the upper layer resist can be made sufficiently thin and the resolution of the pattern can be improved, and at the same time, the pattern can be formed with extremely high dimensional accuracy without damaging the upper layer resist. In addition, since the adhesive can be attached after the pattern is formed on the upper layer resist, not only has the advantage of expanding the selection range of the adhesive, but it is also possible to increase the adhesive layer under ideal conditions without considering the effect of the attached substance when forming the upper layer pattern. There is also an advantage that a resolution pattern can be formed. Further, according to the present invention, since the original pattern can be turned to the inverted state or the original state by a simple method as required, that is, the negative and positive patterns can be formed, there is an advantage that the scope of application of the present invention is widened. Further, referring to the negative pattern, it is generally possible to use a positive resist having a high resolution, so that there is an advantage that a negative pattern having a high resolution can be formed.

[Brief description of drawings]

1 (a) to (d) are pattern forming process diagrams of the first embodiment of the present invention, and FIGS. 2 (a) to (d) are pattern forming process diagrams of the second embodiment of the present invention. FIG. 3 is a pattern forming process diagram of a conventional three-layer resist method. 1 ... energy rays, 2 ... energy ray sensitive resist, 3 ... intermediate layer, 4 ... lower layer resist, 5 ... substrate, 6 ... fluorine-containing polymer, 7 ... adhesive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Hirata No. 3 Morinosato Wakamiya, Atsugi City, Kanagawa Prefecture At Nippon Telegraph and Telephone Corporation Atsugi Electro-Communications Research Laboratory (72) Inventor Shigeru Moriya No. 3 Wakamiya Morinosato, Atsugi City, Kanagawa Japan (56) References JP-A-57-89753 (JP, A) JP-A-58-5735 (JP, A) JP-A-57-202533 (JP, A) JP-A-SHO 58-44715 (JP, A)

Claims (3)

[Claims] 1. In pattern formation using energy rays such as light, electron beams, ions or X-rays, a step of sequentially laminating at least one layer of one or more materials containing a fluorine compound on a substrate, A step of forming a pattern by irradiating at least one layer of a laminated material with an energy ray, and a step of selectively attaching an adhesive material having low adhesion to the fluorine compound only inside or outside the pattern,
A method of forming a pattern, comprising a step of processing the laminated material using the adhesive material as a mask. 2. Polyhexafluorobutyl methacrylate or poly 1,1 dimethyl 2, as the fluorine compound
The pattern forming method according to claim 1, wherein a fluorine-containing polymer such as a copolymer of 2,3,3 tetrafluoropropyl methacrylate or hexafluorobutyl methacrylate and glycidyl methacrylate is used. 3. The pattern forming method according to claim 1, wherein a silicon compound is used as the adhering material.