JPS62230023A - Method for processing fine pattern of insulating substrate - Google Patents

Abstract

PURPOSE:To enable the processing of fine pattern by preventing an irregular exposure of a pattern due to charge-up by using a conductive carbon film formed by generating C2H2 or C2 H2 gas plasma at a specified substrate tempera ture as an underlying thin film. CONSTITUTION:On an insulating substrate to be processed, a thin film which can be etched by oxygen gas plasma etching is arranged as an underlying layer. On this film, a resist layer having a resistance to oxygen gas plasma etching is laid and is exposed to high-energy beams, followed by development. The underlaying thin film is etched by oxygen gas plasma etching using said resist layer as a mask and the substrate to be processed is subjected to dry etching using the underlying thin film as a mask. As the underlying thin film. a conductive carbon film formed by generation C2 H2 or C2 H4 gas plasma at a 200-500 deg.C substrate temperature. In this processing method, there is no need of arranging a conductive layer made of a metal etc. when using ion beam exposure. The processing steps are simplifiedand an influence of damages on the substrate can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Separation] The present invention relates to microfabrication of insulating substrates, and particularly to a microfabrication method using resist no-exposure using a charged beam and dry etching processing. .

[Conventional technology]

As the dimensions of various devices such as LSIs continue to become smaller, the @fine pattern processing method that uses high-energy beams such as '11f-son beams and x% and dry etching has come to be used as a fine pattern processing method. It's here. 0. /μ
As a micro-pattern processing method around m, we used an electron beam resist with high resistance to Ar ion etching on the base, a carphone resist that was behind in reactive ion etching resistance due to each fine fluorine gas, and an electron beam resist with high dry etching resistance due to drinking. A two-layer resist method has been proposed that combines
r-2 Kota 36. Special distribution to Akira to-λ71. /λλ, Machigansho ni'Ir-27117).

However, this carbon film is a plasma polymerized film and has low conductivity. This j% resist method will be briefly explained with reference to FIG. (4) is a carbon layer/J-1 on which high-energy beams such as electron beams and ion beams have low scattering and reflection on the substrate to be processed; Resistance with excellent resistance)/JtF
eS. (B) shows the resist pattern 16 after exposing the resist to high-energy radiation and developing it. (C) is a pattern obtained by dry etching CAPO/1- with [X plasma] using the resist pattern as a mask. and the remaining resist pattern /A is shown. At this time, it is necessary to appropriately select oxygen dry etching conditions so as to directly reflect the pattern of /J'' and the resist pattern of /6.

(1)) is even more resist pattern! Mask K The substrate to be processed is processed by reactive ion etching using a gas containing metal or salt.

This method uses electron beams, ion beams, charged beams, etc. If the substrate to be processed has electrical conductivity, such as silicon and/or metal, the processing method according to Figure 2 can be used. However, if the substrate to be processed is an insulating substrate such as glass or quartz/lithium niobate semi-insulating m-v#c semiconductor, charge-up will occur during exposure with a charged beam, causing the insulating substrate to be processed. An upward pattern will result in incorrect exposure.

This problem occurs not only in the two-layer resist method using the carbon film described above, but also in the case of the conventional electron beam/ion beam filling resist alone. It was necessary to provide a conductive material such as metal (T-Fajitaetal, Opt.
Lett, 7 (/ri, r2). For this reason, due to the complexity of the processing process such as etching and removal of conductive materials,
This causes dimensional changes in fine butterflies, and also causes problems such as damage to the board when cleaning and removing the board due to the direction of contact with the board when providing conductive wire on the board to be processed. was.

[Problems to be Solved by the Invention] The main purpose of the present invention is to solve the problem of improper exposure due to charge-up during 14-light exposure in the ridge processing of an insulating substrate using pattern formation using a load beam. VC Ruru aims to provide a method of fine pattern processing for wire-absorbing substrates that solves the problem.

In the present invention, a thin film that can be etched using an oxygen gas plasma etchant is provided as a lower layer on an insulating substrate to be processed, a resist layer that is resistant to oxygen gas plasma etching is provided on top of the thin film, and the resist layer is formed using a high energy beam. After removing the resist layer with a high-energy beam, the resist layer is developed, and using this resist layer as a mask, the base material is etched using an enzyme gas plasma etching blower. Using this lower layer thin film as a mask, the substrate to be processed is etched. It is a micro-movement pattern processing method in which the groove is formed by dry etching. The method for processing a non-conductive substrate according to the present invention has advantages such as, when using charged beam beam light, there is no need to provide a conductive layer such as poor P4, the processing process is simplified, and there is less damage to the substrate. .

[Implementation-1] Figure 1 is for explaining an apparatus for obtaining a conductive carbon film according to the present invention. FIG. 2 is a schematic diagram of the device used. This device consists of a vacuum bell jar, a substrate for carbon film formation, and a substrate holder 7 with a substrate heating mechanism.
A shutter t is placed above the base and co as necessary. The vacuum bell jar has a Qy (not shown)
A gas introduction pipe 10 is attached to connect the OxH4 gas source and the carrier gas source, and each of the introduction pipes 10 has a flow rate adjustment valve 11. /2 is provided.

Further, below the bell jar l, an exhaust pipe 13 is provided which is connected to an exhaust device (not shown). Plasma generation inside the Belljar l involves passing microwaves from a microwave oscillator≠ through a waveguide j to a microwave outlet 3 for plasma generation.
This is done by introducing it via the . At this time, the magnet t is used to increase the ionization efficiency of the excited supply dregs.

A conductive carbon film for fine pattern processing using the above apparatus can be manufactured as follows.

Place the quartz substrate for carbon film formation on the holder 7 inside the vacuum bell jar, and move inside the vacuum bell jar.
Exhaust to more than Torr. Next, open the R amount control valve //, introduce gas into the empty bell jar through the introduction pipe, and adjust the gas pressure to 0-' Tor.
Make it r. Next, use the microwave oscillator μ to generate microwaves.
Oscillate with OW to generate Ar gas plasma inside the vacuum bell jar. In this state, the surface of the quartz substrate is cleaned for 70 to 30 minutes. After cleaning, heat the substrate holder 7 to 100'C to 700"C to set the substrate temperature, introduce 0zkb or C2H4 gas into the vacuum bell jar, and adjust the gas pressure to /O-' to JX/0-"T.
Set to the range of orr. Next, follow the same procedure as the second cleaning with Ox Tom or C! Generates gas plasma. At this time, by opening the shutter t, a carbon film is formed on the substrate λ. Table 1 shows the conductivity of carbon films prepared at substrate temperatures of 100''C to 700@C and the deposition time for a film thickness of 0.j pm.
s l 0OlzF2 * Reactive etching rate ratio by 004 gas (photoresist, microposit l
≠00 (relative value with the product name) is shown in Table 2.

Table 1 As described above, when the temperature of the fabricated substrate is raised to 00''C or above, the conductivity of the fabricated carbon film increases dramatically.The conductivity of the fabricated carbon film is TD8 Thermal Desoporption Spec
troscopy), the temperature at which hydrogen desorption begins is 2θ
This is because a carbon film produced at a temperature of OO''C or higher near 0°C is richer in carbon than one produced at a temperature below 0°C, and exhibits graphite-like properties as the temperature increases. In this way, conventional OOVDm (Che
Mical Vapar Deposition )K
It is easier to obtain conductive carbon at lower temperatures.

(Etching conditions; /Pa + RF power 0. J W/
, j) As shown in Table 1, the oxygen dry etching rate of the carbon film prepared by raising the substrate temperature is about 2 to 2 times higher than that of Microposit l, and the upper layer resist is It has an etching rate fast enough to transfer the pattern. In addition, the dry etching resistance against fluorine and chlorine gases is higher than that of the photoresist Microposite/4AOO, which was conventionally considered to have the highest etching resistance.
K comparison t! It is characterized by having more than twice the resistance.

Next, a method for processing a fine pattern on an insulating substrate using this conductive carbon film will be described based on an example.

〔Example/〕

A silicon-based negative resist (sensitivity to pc,
, iaa > was applied to a film thickness of 0.01 fpm.

The wall-covered resist was irradiated with -sonograms in a lattice pattern over a length of 711 m at a pitch of 0.2 μm.

After that, when developed with cyclohexane and rinsed with cyclohexane, a pattern with a line width of 0./μm was formed on the resist on the carbon film whose substrate temperature was Hxoo"c or higher, but once the substrate temperature was 100"C, a pattern with a line width of 0./μm was formed. "C and the resist on the carbon film at room temperature caused charge-up during electron beam irradiation, making it impossible to form a fine line pattern. Next, reactive ion etching with oxygen gas was performed using the formed resist pattern as a mask. (Oxygen flow rate (OSCCM) - vacuum pressure/Pa.

Ordinary F power 0. /w/I-,i) was flown at a rate of /2 to transfer the pattern to the carbon film. Substrate temperature 20
0″G.

2! O"0.300"C, 4LoO'c, ! 00'C
In the carbon film prepared with the line width 0. /pmS film thickness 0.
A 2 μm carbon pattern was obtained, but the substrate temperature tO
The carbon film produced at 700@C had a soft film quality, and the pattern collapsed. Next, using the carbon film pattern as a mask, the underlying quartz substrate was subjected to reactive ion etching with 01F gas (gas flow i, lQ5CQ4, vacuum pressure 2Pa1, F power αjw) for a total of 70 minutes. Finally, oxygen gas plasma ashing was performed for j minutes to remove the remaining carbon film. As a result, it was possible to process a lattice pattern on a quartz substrate with a line width of 0/μm and a depth/pm.

[Example 2] A conductive carbon film was formed on a lithium niobate substrate (C-axis orientation) to a film thickness of α! using c-juyama gas at a substrate temperature of so'c. μm was deposited. Next, in the same manner as in Example 1, four-photodevelopment with electron beams and reactive ion etching with oxygen were performed, and a line width of 0.7 μm and a film thickness of 0.5 μm were formed on the lithium niobate substrate.
J″μm lattice carbon pattern. Rough x0
3F11 gas reactive ion etching (gas flow rate, 2
0SCCM%X air pressure/, j Pa, 几F power 0
．． 3 w/cd) for 70 minutes, oxygen gas plasma ashing was performed to remove the remaining carbon film! It was applied for a minute. As a result, the lithium niobate substrate has a line width of 0. It was possible to process a lattice pattern with a depth of 1/μm/pm.

[Example 3] 1 [[-V group semiabsolute substrate InP was also formed and patterned with a conductive carbon film in the same manner as in Example 004 Fx
* By etching anti-chemical hexavalent ions of Co gas! 5
．． lj width 0. / pm's fine pattern sword Loe was possible.

In this way, the carbon film fabricated at a substrate temperature of 200 to 00°C has a 44-dimensional pattern in a fine pattern processing method using a pattern forming method using charged beam exposure on an insulating substrate typified by quartz, lithium niobase (tInP). of! L, I
The pattern can be easily transferred by N element dry etching, and it has sufficient resistance to reactive dry etching of the substrate to be processed, making it possible to process insulating substrates with greater ease and precision than ever before.

〔Effect of the invention〕

As explained above, the manufacturing temperature according to the present invention is 200°C.
-J-00°C carbon film and the pattern forming method using it are based on ``Itf14:M'', which is a two-layer resist system with easy pattern transfer by dry etching with oxygen, and reactivity with halogen yarn gas. Due to the lack of ion etching resistance, quartz, lithium oxide (1 OP) + In
Is it easy and convenient for processing various substrates such as P? It has the advantage of being able to be used with A3 accuracy.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used for applying a fine patterning carbon film according to the present invention to a substrate to be processed, and FIG. 2 is a process diagram of a two-layer resist method. L...Vacuum bell jar, C...Substrate for carbon film formation, 3...Microwave outlet for plasma discharge, μ...
・Microwave oscillator!・・・Microwave waveguide, bu・
... Magnet, 7... Board holder, ? ...shutter, ri and 10...gas introduction pipe, /l and /2...
Flow rate kun 1 section pulp, /J...exhaust pipe, llA...board, l! ...Carbon IIQ, /J...Resist layer.

Claims (1)

[Claims] A thin film that can be etched by oxygen gas plasma etching is provided as a lower layer on the insulating substrate to be processed, the resist layer is exposed to high-energy radiation, the resist layer is developed, and the lower thin film is exposed to oxygen gas using the resist layer as a mask. In a fine pattern processing method consisting of etching by plasma etching and dry etching the insulated substrate using this lower layer thin film as a mask, C_2H_2 or C_2H_4 gas plasma is generated as the lower layer thin film at a substrate temperature of 200°C to 500°C. A method for processing a fine pattern on an insulating substrate, characterized by using a conductive carbon film formed by