JPH05140727A - Pretreatment of substrate at film formation by sputtering - Google Patents

Abstract

PURPOSE:To obtain a sputtered film having high adhesive strength by immersing a substrate prior to sputtering into a warm concd. hydrochloric acid. CONSTITUTION:The ceramic substrate 1 is immersed into acetone 6 and is ultrasonically cleaned; thereafter, the substrate is further ultrasonically cleaned in pure water 11 after degreasing with an alkaline degreasing liquid 'Alprep(R)' kept at 60 deg.C. The substrate is then immersed for two minutes in the warm 14N hydrochloric acid 12 kept at 60 deg.C in a thermostatic tank 9. Etching traces 2 are thereby generated on the surface of the ceramic substrate 1. The adhesive strength of a Cr film 3 infiltrating the etching traces 2 is improved if the Cr film 3 and Ni film 4 are deposited on such substrate in a vacuum tank 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate pretreatment method during sputtering film formation during thin film formation by sputtering film formation, for example, for forming electrodes on a piezoelectric element.

[0002]

2. Description of the Related Art Conventionally, as a pre-process of a ceramic substrate for forming a film by a sputtering method, after inserting the substrate into a vacuum chamber, Ar (argon) gas is introduced into the vacuum chamber and ionized by an electric field. It was common to remove surface contaminants by a dry process such as a reverse sputtering method in which the ionized gas is made to collide with the substrate surface to knock out the contaminants adhering to the substrate surface. With the sputtering method, the element substrate is inserted into a vacuum chamber provided with a target of a substance forming an electrode material, Ar gas is introduced, and then an electric field is applied.
This is a method in which particles of an electrode constituent substance are knocked out by colliding particles of a gas ionized gas with a target, and the particles are deposited on the element substrates placed facing each other to form an electrode thin film.

[0003]

However, the conventional method is not sufficiently effective in preventing the reduction of the adhesion strength with the substrate due to the residual stress of the coating film, and the adhesion strength of the electrode film prepared by the conventional technique is reduced. The value when evaluated by the peeling method is 3
It was a very low value of 0 to 50 kg / cm ² .

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a pretreatment method for obtaining a sputtered film having high adhesion strength.

[0005]

In order to achieve this object, the pretreatment method of the present invention includes an etching step using warm concentrated hydrochloric acid.

[0006]

According to the pretreatment method of the present invention having the above-mentioned constitution, the grain boundaries of the substrate particles are selectively etched by immersing the substrate before sputtering in hot concentrated hydrochloric acid to form etching traces.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, referring to FIG. 1, the structure of an electrode film produced by the pretreatment method of the present invention will be described. A PbZrO ₃ (lead zirconate) -PbTiO ₃ (lead titanate) ceramic substrate 1 will be described. Is composed of particles of PbZrO ₃ and PbTiO ₃ , and the grain boundary near the surface has an etching mark 2 of several hundred to several thousand angstrom due to the etching by the pretreatment. The Cr (chromium) film 3 deposited on the substrate has also penetrated into the etching traces 2, and the Ni (nickel) film 4 is further formed on the Cr film 3.
Have been deposited.

Next, the manufacturing process of the electrode film of this embodiment will be described with reference to FIGS.

First, the ceramic substrate 1 is immersed in acetone 6 in a beaker 5 for solvent cleaning as shown in FIG. 2 (a), and ultrasonic cleaning is performed by an ultrasonic cleaning device 7 for 5 minutes. Then, as shown in FIG. 2 (b), after being forcedly dried by the air blow of the air spray 8, as shown in FIG. 2 (c), the alkaline degreasing liquid Alprep (Okuno Pharmaceutical Co. (Manufactured) 10 for 5 minutes. Subsequently, as shown in FIG. 2D, ultrasonic cleaning is performed in pure water 11 by the ultrasonic cleaning device 7 for 10 minutes, and then, as shown in FIG.
As shown in (e), the concentration 14 kept at 60 ° C in the constant temperature bath 9
It is dipped in the specified warm hydrochloric acid 12 for 2 minutes. Next, FIG. 2 (f)
As described above, the water is washed in the washing tank 13 for 1 minute, and the pretreatment process is completed. When the pretreatment is completed, etching marks 2 are formed on the surface of the ceramic substrate 1 as shown in FIG.
Then, as shown in FIG. 4, the ceramic substrate 1 is carried into the vacuum chamber 14 of the sputtering apparatus, and the Cr target 15 and Ni
The target 16 is sputtered in this order, and the Cr film 3 and the Ni film 4 are deposited on the ceramic substrate 1. The Cr film 3 penetrates into the etching mark 2 and the adhesion strength is improved by the anchor effect.

Table 1 shows the results of evaluation of the adhesion strength of the obtained electrode film by the peeling method.

[0012]

[Table 1]

As described above, it can be seen that the pretreatment method of this embodiment provides a high adhesion strength of about 140 kg / cm ₂ . Since the film having high adhesion strength can improve reliability as an electrode, the electrode film having excellent reliability can be obtained by the pretreatment method of this embodiment.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention. For example, in the present embodiment, the treatment is performed by immersing the ceramic substrate in warm hydrochloric acid, but this process may be performed by spraying warm hydrochloric acid with a spray, or by applying hot hydrochloric acid onto the ceramic substrate with a brush. Is. Further, in this embodiment, the thin film to be sputtered is the first layer Cr film and the second layer Ni film, but this is Ti (titanium), Cu (copper), Al (aluminum), Au (gold), Ag ( It is also possible to use silver) and its alloys, and it is also possible to use not only the electrode application but also the metal film or oxide film for decoration, corrosion resistance and abrasion resistance.

[0015]

As is clear from the above description, by etching the surface of the ceramic substrate with warm hydrochloric acid, a sputtered film having high adhesion can be obtained on the ceramic substrate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electrode of an embodiment to which the present invention is applied.

2A to 2F are explanatory views sequentially showing a pretreatment process of the electrode substrate of the present embodiment.

FIG. 3 is a cross-sectional view of the substrate after the pretreatment of this embodiment.

FIG. 4 is an explanatory view showing an electrode sputtering process of the present embodiment.

[Explanation of symbols]

 1 Ceramics Substrate 2 Etching Trace 3 Cr Film 4 Ni Film 5 Solvent Cleaning Beaker 6 Acetone 7 Ultrasonic Cleaner 8 Air Spray 9 Constant Temperature Bath 10 Alkaline Degreaser Alprep 11 Pure Water 12 Warm Hydrochloric Acid 13 Water Washing Bath 14 Vacuum Tank 15 Cr Target 16 Ni target

Claims (2)

[Claims] 1. A substrate pretreatment method during sputtering film formation, which comprises etching the substrate surface with warm hydrochloric acid as a pretreatment for forming a film on a ceramic substrate by a sputtering method. 2. As a pretreatment for forming a film on a ceramic substrate by a sputtering method, the substrate surface is etched with warm hydrochloric acid to selectively form an etching mark at a grain boundary portion of ceramic particles. Substrate pretreatment for film.