JPH0360121A - Dry etching - Google Patents

Abstract

PURPOSE:To perform a dry etching low in particle level on an SiO2 film without using fluorocarbon by gas a method wherein after a first etching is performed in a first chamber, a second etching is perform with the mixed gas of fluorine gas not containing carbon and oxygen gas in a state that a material containing carbon as its constituent element is arranged on the periphery of a silicon substrate. CONSTITUTION:A silicon substrate 10 is installed on a disc electrode 25b in a first chamber 20 and a reactive ion etching which is a first etching is performed using nitrogen trifluoride as etching gas. Then, the substrate 10 is transferred on a disc electrode 26b in a second chamber 21 in a vacuum state through a coupling cylinder 22, is supported by clamps 28 made of polyarylate and a second etching is performed to remove 10% of the remnant of an SiO2 film 11. In this second etching, a mixed gas of sulfur hexafluoride and hydrogen is used as the etching gas. In the first etching process in the chamber 20 above mentioned, particles are never adhered in the interior of the chamber and the like because carbon is not contained in the etching gas and in the chamber 20.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dry etching method, and more specifically, a dry etching method that enables anisotropic etching of silicon dioxide (SiO,) without using fluorocarbon gas. This is related to.

[Summary of the invention] The present invention relates to a silicon substrate formed on a silicon substrate.

A method for dry etching a film includes a step of performing first etching with a fluorine-based gas that does not contain carbon in a first chamber that does not contain a material that contains carbon as a constituent; A step of performing a second etching with a mixed gas of carbon-free fluorine-based gas and hydrogen (H7) in a second chamber disposed around the silicon substrate is performed sequentially. 5i on silicon substrate with suppressed deposition
This makes it possible to perform selective etching of the O1 film, and also to realize a clean process that keeps the particle level low.

[Prior Art] The selective dry etching technique of silicon dioxide formed on a silicon substrate is an in-shell etching process that is also used in the production process of large-scale integrated circuits from about 64K DRAM. The etching gas used for such etching is CHF5. CF'4+Ht, C,F@+CHF
', a fluorocarbon gas with a low fluorine (F)/carbon (C) ratio is mainly used.

This is because these gas systems effectively generate CPx, which is an etchant for SiO, and create a relatively carbon-rich state in the plasma.
, the etching progresses as shown in Figure 3 without causing any deposition, and St causes a convenient reaction in which carbon-based deposition occurs and etching stops, resulting in selective etching on the silicon substrate. It is possible.

In the same figure, 1 indicates a silicon substrate, 2 indicates a 5ift film, and 3 indicates a resist.

In addition, as another technique of this kind, Japanese Patent Application Laid-Open No. 621546
The invention described in Japanese Patent No. 27 is known, in which a mixture of carbon tetrafluoride, which is a fluorocarbon gas, methane trifluoride, and oxygen (0,) is used as an etching gas.

[Problems to be Solved by the Invention] However, in recent years, there has been a demand for the elimination of CFCs due to global environmental issues, etc.

It is becoming difficult to use fluorocarbon gas, which has been mainly used for etching, and there is a possibility that it may become completely unusable in the future.

Furthermore, in the technique described in JP-A-62-154627, since the etching gas contains oxygen (0. Ta.

The present invention was devised by focusing on such problems, and it is possible to produce a sinusoidal material without using fluorocarbon gas.

The purpose of the present invention is to provide a dry etching method with a low particle level that enables selective anisotropic pressurization of a film.

[Means for Solving the Problems] Therefore, the present invention provides 5iO formed on a silicon substrate.
In the method of dry etching a Z film, a first etching process is performed using a carbon-based gas that does not contain carbon in a first notch that does not contain a material that contains carbon as a constituent element; Sequentially performing a second etching process using a mixed gas of carbon-free fluorine-based gas and hydrogen (H7) in a second chamber in which the element material is arranged around the silicon substrate. is the solution to this problem.

[Operation] Since the first chamber does not contain a material containing carbon as a constituent element, and the etching gas for the first etching does not contain carbon, carbon-based deposits (
particles, etc.) are not generated.

After the first etching is performed in the first chamber, the silicon substrate on which the 5iOt film has been etched to a predetermined depth is transferred to the second chamber, and carbon is formed around the silicon substrate. With the element materials arranged, carbon-free fluorine gas and hydrogen (H
By performing the second etching with the mixed gas of 2),
The SjO film is selectively etched by the action of carbon released from the material containing carbon and hydrogen (H2) in the gas. If this second etching time is short,
There will be even less carbon-based deposits in the second chamber.

[Example] Hereinafter, details of the dry etching method according to the present invention will be explained based on an example shown in the drawings.

FIGS. 1A to 1D are cross-sectional views showing the etching process of an embodiment of the present invention, and FIG. 2 shows an etching apparatus used in this embodiment.

In this embodiment, an etching apparatus as shown in FIG. 2 is used to perform two-step etching.

This etching device connects a first chamber 20 and a second chamber 21 so that they can communicate with each other through a connecting tube 22.
2 and 1st. Gate valves 23 and 24 are interposed between the second chambers 20 and 21, respectively.

In addition, the first chamber 20. Inside each of the second chambers 21, there is a pair of disc electrodes 25a facing each other.

25b, 26a, and 26b are provided. In addition, the second
In the figure, a is a silicon substrate l on which a 5i01 film 11 is formed.
For the sake of explanation, both chambers 20.2
It is supported by clamps 27 and 28 on one of the disk electrodes (susceptors) 25b and 26h in 1. In addition, clamp 2
7 is made of ceramics, and the clamp 28 is made of polyarylate containing carbon as a constituent element.

In this embodiment, as shown in FIG. 1A, a silicon substrate 10
The SiOx film 11 formed thereon is anisotropically dry etched. First, as shown in Figure 1H,
A resist I2 is applied onto the Sin film 11 and patterned.

Next, the silicon substrate 10 is placed on the disk electrode 25h in the first chamber 20, and supported by the ceramic clamp 27 as described above. Then, a first etching process, reactive ion etching (RTF), is performed using nitrogen fluoride (N P 3 ) as an etching gas. In this case, Sin.

Approximately 90% of the etching depth of the film 11 is etched (FIG. 1C).

Note that to monitor the etching depth, for example, the first
This is possible by providing a laser interference film thickness monitor or the like in the chamber 20.

Next, the silicon substrate 10 is transferred in a vacuum state onto the disk electrode 26b of the second chamber 21 via the connecting tube 22, and is supported with the clamp 28 made of polyarylate as described above.
A second etching is performed, and the remaining 1 of the film 11 is
Remove 0%. (Figure 1D). This second etching is performed using sulfur hexafluoride (SF'@) as the etching gas.
) and hydrogen (H7). .

In the first etching process in the first chamber 20 described above, since carbon is not contained in the etching gas and in the first chamber 20, particles do not adhere to the inside of the chamber or the like. Further, in the second etching process in the second chamber 20, no fluorocarbon gas is used as the etching gas, and the etching time is short, so that the generation of particles can be suppressed to an extremely low level.

Although the embodiments have been described above, the present invention allows for various other design changes. For example, in the above embodiment, the clamp 28 in the second chamber 2I was made of polyarylate, but polycarbonate Other materials containing carbon as a constituent may also be used.

Further, in the above embodiment, the first chamber 20 is made of Si.
n, 90% of the depth of the film 11 was etched, but 80% ~
A depth range of about 90% can be applied.

Furthermore, in the second etching process, a mixed gas of SF and Hl was used as the etching gas, but in addition, a mixed gas of nitrogen fluoride (NFs) and hydrogen (H2), and a chlorine fluoride (CffFa) were used. ) and hydrogen (H2) can of course be used.

Furthermore, in the present invention, it is of course possible to use an etching apparatus having a structure other than the etching apparatus used in the embodiment.

[Effects of the Invention] As is clear from the above description, the dry etching method according to the present invention has the effect of selectively etching a 5iOz film on a silicon substrate while suppressing carbon-based deposits as much as possible. Therefore, the particle level is low and anisotropic etching can be performed without using fluorocarbon gas.

[Brief explanation of drawings]

1A to 1A are cross-sectional views showing the steps of an embodiment of the dry etching method according to the present invention, FIG. 2 is a schematic diagram of an etching apparatus used in the embodiment, and FIG. 3 is a sectional view of a conventional example. It is. 10...Silicon substrate, 11...Sin, film, I2
...Resist, 20...First chamber, 21...
Second chamber, 27...clamp (ceramics),
28...Clamp (borea arylate). NF3 C day F3 I) ↓ If IJ's Kōgu Y db Figure 3

Claims (1)

[Claims] (1) In a dry etching method for a SiO_2 film formed on a silicon substrate, the first etching is performed using a fluorine-based gas that does not contain carbon in a first chamber that does not contain a material containing carbon as a component. and a step of performing a second etching with a mixed gas of carbon-free fluorine-based gas and hydrogen (H_2) in a second chamber in which a material containing carbon is arranged around the silicon substrate. A dry etching method characterized by sequentially performing.