JP3112442B2 - Metal electrode forming method and secondary product removing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal electrode, and more particularly to the removal of a secondary product using an aerosol.

[0002]

2. Description of the Related Art
Ir (iridium), Pt as electrodes of ferroelectric element
(Platinum) or the like is used. A method for forming such an Ir electrode will be described. Similar to a normal Al electrode, an Al layer is formed on the entire surface, a resist having a predetermined pattern is formed, and etching is performed. Then, the resist is removed by ashing. Thus, an Ir electrode is formed.

However, in the case of Ir or Pt, a secondary product 15a is formed on the side wall of the resist 32 during the etching process, as shown in FIG. 3C. Further, when the resist 32 is removed by an ashing process, the side wall 15a of the secondary product remains as shown in FIG. 3D. Even if wet etching is performed in this state, the side wall 15a remains as shown in FIG. 4, and the coverage of the aluminum wiring and the like formed thereon via the interlayer film is reduced. In particular, by the ashing process for removing the resist, the secondary product becomes a stronger film, and the removal becomes more difficult.

On the other hand, Japanese Patent Application Laid-Open No. 8-298252 discloses a method of removing a resist on a substrate by using an aerosol of frozen argon. Briefly, first, a pressurized gaseous argon-containing gas stream at a temperature equal to or higher than the liquefaction temperature of argon is expanded and solidified, and an aerosol of frozen argon particles is caused to collide with a resist to be removed. Then, the substrate is moved linearly. This allows
The resist is removed. The conditions at this time were as follows: the flow rate of argon aerosol was 1.4 SCFM at 95 ° K, and the temperature and flow rate of nitrogen of the carrier gas were 1.8 SC at 195 ° K.
FM.

Therefore, the inventor conducted an experiment of removing a resist having a secondary product formed on the side wall using the aerosol. However, under the above conditions, the resist having the secondary products formed on the side wall could not be removed.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a method for removing a secondary product formed on a side wall of a resist by using the aerosol, and reliably removing the secondary product. An object of the present invention is to provide a method for forming an electrode that can be performed.

[0007]

According to a first aspect of the present invention, in the method of forming a metal electrode, after removing the resist, a secondary product formed on a side wall of the resist by the anisotropic etching is aerosolized. A metal electrode forming method for removing particles using particles of an inert gas,
Xenon is used as the source.

[0008]

[0009]

[0010]

[0011]

Hereinafter, terms used in the present specification will be described.

"Forming a metal electrode layer on a substrate" means not only forming the metal electrode layer directly on the substrate but also forming another layer between the substrate and the metal electrode layer. And indirectly formed.

The term "inert gas" also includes the case where the inert gas is active with respect to the secondary product to be removed.

The term "inert gas particles" includes liquid particles as well as frozen solid fine particles.

[0016]

In the method of forming a metal electrode according to the first aspect, after the resist is removed, a secondary product formed on the side wall of the resist by the anisotropic etching is:
It is removed using an aerosolized inert gas. Thus, by removing the resist prior to removal using the aerosolized inert gas, only the sidewalls of the secondary products are left. Therefore, the removal can be efficiently performed using the aerosolized inert gas. In addition, xenon is used as the inert gas.
You. Therefore, compared to the case using argon,
Efficiently, the secondary products can be removed.

[0017]

[0018]

[0019]

[0020]

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for forming an electrode according to the present invention will be described with reference to the drawings. As shown in FIG. 3A, a lower electrode layer 5, a ferroelectric film 7, and an Ir electrode layer 25 are formed on a substrate 2 on which an insulating film 3 is formed. Next, as shown in FIG. 3B, a resist 32 for the upper electrode is formed.

When anisotropic etching is performed in this state, the electrode layer 25 is etched, and the upper electrode 15 is formed. At this time, the side wall of the resist 32 is
As shown in C, the secondary product 15a of Ir is attached.

Next, the resist 32 is removed. In the present embodiment, the resist 32 is removed using an etching solution having high selectivity to Ir. Therefore, the ferroelectric film 7 below the upper electrode 15 is not adversely affected by the plasma. Specifically, etching was performed using an organic alkali solution at 50 ° C. for 15 minutes to remove the resist having a thickness of 1 μm.

Next, a secondary product removal process using an aerosol is performed with the resist 32 removed as described above and the interior of the secondary product 15a being hollow. The principle of an apparatus for performing a secondary product removal process using an aerosol is described in the above-mentioned Japanese Patent Application Laid-Open No. 8-298252, but will be briefly described with reference to FIG.

The mixture of argon and nitrogen is supplied to the heat exchanger 53
And some or all of the condensed components are liquefied, and are discharged from the nozzle 61 into the vacuum chamber 51. At this time, since the inside of the vacuum chamber 51 is maintained lower than the inside of the nozzle, it is expanded by this discharge. The argon particles emitted from the nozzle 61 are accelerated by the inert gas supplied from the gas nozzle 62 and collide with the substrate 1. The substrate 1 is moved in the vacuum chamber 51 by a scanning mechanism (not shown).

As a result, as shown in FIG. 1, the particles 60 of the argon gas collide with the secondary product 15a, and the secondary product 15a is removed.

In this manner, the secondary products 15a generated on the side walls of the resist can be efficiently removed. Thereafter, in the same manner as in the related art, etching is performed using a resist to form the ferroelectric film 7 and the lower electrode layer 5.

In this embodiment, the flow rate of the argon aerosol is 50 SLM (Standard Litter per Minute).
And the flow rate of the carrier gas was 5 SLM. The scanning speed of the substrate was set at 1 cm / sec.

When performing the secondary product removal process using the aerosol, the substrate 1 may be heated so that the argon particles collide with the substrate. This promotes removal by thermal stress. The heating temperature needs to be lower than the heat resistant temperature of the ferroelectric film 7. For example, PZT is about 200 ° C. For example, it may be heated before being carried into the vacuum chamber, or may be further heated in the vacuum chamber.

In this embodiment, argon gas is used, but xenon (Xe) gas may be used.
Xenon (Xe) gas has a larger mass than argon gas, so that secondary products can be removed more effectively. Also in this case, it is desirable to maintain the pressure in the vacuum chamber 51 at the triple point or lower, similarly to argon.

In this embodiment, the resist 32 is removed by using an etching solution having high selectivity to Ir. However, the resist may be removed by ashing.

In this embodiment, PZT is used as the ferroelectric film, but other ferroelectric films can be similarly applied.

In this embodiment, the case where Ir is used as the electrode of the ferroelectric element has been described.
The same applies to other metals such as Pt.

In this embodiment, the case where Ir is used as the electrode of the ferroelectric element has been described.
For the removal of chemically stable secondary products of metals,
The same can be applied.

In this embodiment, the case where the lower electrode is formed on the insulating film 3 formed on the substrate 2 has been described, but the insulating film is formed on the layer on which elements such as transistors are formed. May be formed to form the lower electrode.

[Brief description of the drawings]

FIG. 1 is a view showing a state of removing a side wall using an aerosol according to the present invention.

FIG. 2 is a diagram for explaining the principle of an aerosol generating device.

FIG. 3 is a view showing a step of forming electrodes.

FIG. 4 is a view showing a remaining state of a side wall of a conventional secondary product.

[Explanation of symbols]

 2 Substrate 5 Lower electrode layer 7 Ferroelectric film 15 Upper electrode 15a Secondary product 60 Argon particles

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Claims (1)

(57) [Claims] A step of forming a metal electrode layer on the substrate; a step of forming a resist on the metal electrode layer; a step of performing anisotropic etching using the resist as a mask; and removing the resist. step, wherein the post-resist removed, the secondary products formed in the side wall of the resist by the anisotropic Etchiggu metal be removed using the particles of the inert gas is aerosolized
A method for forming an electrode, wherein xenon is used as the inert gas .