JPH05175174A - Reactive dry etching method for dielectric film - Google Patents

Abstract

PURPOSE:To provide a dry etching method by which the etch rate of a dielectric film can be remarkably improved. CONSTITUTION:After a PLZT film 2, SiO2 film 3, and resist film 4 are successively formed on a substrate 1, a required resist pattern is formed by using a photolithographic technique and the SiO2 is etched. Then ions of a halogen element are implanted into the area to be etched of the PLZT film 2 by using the SiO2 film 3 as a mask. After etching the film 2, ion beam etching is performed in the atmosphere of a halogen etching gas. An etching rate which is 10 times or more as high as the etching rate obtained when no ion implantation is made can be obtained, because the implanted amount of ions reaches >=1,018cm<-3>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive dry etching method for a dielectric film.

[0002]

2. Description of the Related Art BaTiO ₃ , SrTiO ₃ , PbTiO ₃
Dielectric oxide materials composed of ₃ , PbZrO ₃ , LiNbO ₃ , Bi ₄ Ti ₃ O ₁₂ or solid solutions thereof have been applied to various functional devices such as capacitors, piezoelectric elements and electro-optical elements. In recent years, attempts have been made to reduce the thickness of these materials in order to meet the demands for device miniaturization and high integration, and thin film devices such as nonvolatile memory, pyroelectric infrared sensor, ultrasonic sensor, and optical switch have been developed. Prototyped. To develop these thin film devices, it is essential to establish not only film forming technology but also processing technology. In particular, with the miniaturization of devices and the progress of peripheral technologies, it is desired to develop a dry etching technique which is excellent in the processing accuracy and processing speed of the dielectric film. On the other hand, a typical (Pb, La) (Zr, Ti) O ₃ (PL
ZT) Reactive Dry Etching, APPLIED OPTICS, 1986, 25th.
Vol. 9, No. 1, pp. 1508-1510. In this paper, PLZT is etched by Ar ion beam under 2 × 10 ⁻⁴ Torr, and C ₂ F ₆ or C ₂
We are investigating the effect of the reaction gas of F ₄ .

[0003]

In the reactive dry etching reported in the above-mentioned paper, the reactive gas C ₂ F _{6 is used.}
Alternatively, the effect of increasing the etching rate of PLZT by adding CF ₄ is that the ion beam current density is 0.8.
It is limited to mA / cm ² or less, and above that, the etching rate is reduced by adding a reaction gas. Moreover, even when there is a reaction gas effect, the etching rate is 35 nm / min at the maximum, and 2-3 times when there is no reaction gas.
It is only about twice. An object of the present invention is to provide a dry etching method which solves the problems of the conventional reactive dry etching described above and makes the reaction between the dielectric film and the etching gas efficient so as to improve the etching rate. ..

[0004]

The present invention has a chemical formula of AB.
It is represented by O ₃ , and as A, Pb, La, Sr, Ba, Li
Containing one or more elements selected from
In a method of dry-etching a dielectric film containing one or more elements selected from i, Ta, and Nb using a halogen-based gas, a halogen element is ion-implanted into a region to be etched in advance. Is the reactive dry etching method.

[0005]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a process flow of the present invention. First,
PLZ on the substrate 1 by the RF magnetron sputtering method
A T film 2 was produced. The target is (Pb _0.91 , L
a _0.09 ) (Zr _0.65 , Ti _0.35 ) _0.9775 O ₃ composition powder in Ar / O ₂ mixed gas under 10 mTorr,
A film having a thickness of 0.5 μm was formed at a substrate temperature of 600 ° C. This PL
An SiO ₂ film 3 of 1 μm is formed on the ZT film 2 by the LPCVD method.
m, the resist film 4 was applied to a thickness of 2 μm (see FIG. 1).
(A)). Then, a desired resist film pattern was formed by the photolithography technique. S using resist 4 as a mask
After etching the io ₂ film 3 (FIG. 1 (b)) and removing the resist, the SiO ₂ film 3 is used as a mask for the PLZT film 2
A halogen element selected from F, Cl, Br, and I is ion-implanted into the region to be etched (see FIG. 1).
(C)). Next, ion beam etching was performed in a halogen-based gas atmosphere selected from HF, CF ₄ , HCl, HBr, and HI. Mount the sample in the vacuum chamber 1
After evacuating to × 10 ^-6 Torr, a halogen-based gas containing ion-implanted halogen element is introduced to obtain 2 × 10
^-4 Torr, the substrate temperature was 200 ° C., and the ion beam current was 0.8 mA / cm ² (FIG. 1D).

FIG. 2 shows the amount of halogen element ion implantation and PL.
The relationship of the etching rate of the ZT film is shown. In the figure, 5 is the case of F injection and CF ₄ gas etching, 6 is F injection,
In the case of HF gas etching, 7 is Cl injection, HC
1 gas etching, 8 is Br injection, HBr
This is the case of gas etching, and 9 is the case of I implantation and HI gas etching. As can be seen from the figure, when the ion implantation amount of the halogen element is 10 ¹⁸ cm ⁻³ or more, the etching rate sharply increases and is 10
More than double the etching rate was obtained. Instead of PLZT, SrTiO ₃ , BaTiO ₃ , LiNbO ₃ , LiT
The same experiment as above was carried out for the aO _3, Bi ₄ Ti ₃ O ₁₂ film, and almost the same results were obtained.

[0007]

As described above, according to the present invention, the rate of the reactive dry etching of the dielectric thin film can be remarkably improved, and the processing technique for manufacturing a thin film device is improved.

[Brief description of drawings]

FIG. 1 is a substrate cross-sectional view showing a reactive dry etching method according to the present invention in the order of steps.

FIG. 2 is a diagram showing a relationship between an ion implantation amount of a halogen element and an etching rate of a PLZT film.

[Explanation of symbols] 1 substrate 2 PLZT film 3 SiO ₂ film 4 resist film

Claims (1)

[Claims] 1. The chemical formula is represented by ABO ₃ , and A is P
A dielectric film containing one or more elements selected from b, La, Sr, Ba and Li and containing one or more elements selected from Zr, Ti, Ta and Nb as B is dry-etched using a halogen-based gas. In the method, a reactive dry etching method for a dielectric film, characterized in that a halogen element is ion-implanted into a region to be etched in advance.