JPH02280114A - Formation of groove-shaped electrode to plzt light transmittable ceramics - Google Patents

Abstract

PURPOSE:To make the more effective formation of large-sized parts and mass production by forming comb-shaped patterns by using the technique of photolithography, then forming grooves by a chemical etching and imparting electrodes, thereby forming groove-shaped electrodes. CONSTITUTION:The surface of lanthanum-modified lead zirconate titanate PLZT is coated with a photoresist film and is exposed and developed by using a mask having prescribed electrode patterns, by which the resist film is stripped only from the pattern parts and the sample surface is exposed. The sample with the patterned resist film is then put into an etching soln. The etching soln. is an aq. soln. mixture composed of hydrofluoric acid and nitric acid and the concn. thereof is determined by the target groove shape and the corrosion resistance of the photoresist. The electrodes are imparted while the resist is held stuck and finally, the resist is stripped and the groove-shaped patterned electrodes are obtd. The grooving of the comb-shaped patterns is facilitated in this way and this method is adequate for the mass production as well. The uniformity of electric fields is improved when this method is combined with an electroless plating.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides lanthanum-modified lead zirconate titanate (hereinafter referred to as PL
The present invention relates to a technique for forming groove-shaped electrodes on translucent ceramics (referred to as ZT) by a method that is simple and suitable for mass production.

[Prior Art] PLZT translucent ceramics has a large electro-optic effect, and is therefore a material that is expected to be applied as material elements for optical shutters, light valves, optical switches, optical modulators, etc. in the field of optoelectronics. It is.

The characteristics of these elements are that they control light transmittance by transmitting electrical signals as changes in the plane of polarization, so unlike mechanical shutter switches, etc., they have no moving parts and can be made compact, and they are easy to control. The speed is extremely high. However, since the voltage that is the electrical signal to be controlled is very large, the response speed of the electrical signal transmission circuit cannot be controlled at high speed, and there is a problem that the high-speed control characteristics cannot be fully utilized. Therefore, it is necessary to reduce the applied voltage.

In order to reduce the driving voltage, a comb-shaped electrode as shown in FIG. 2 is a known technique. The stiffness was designed so that the same electric field is applied even if the distance between the electrodes is narrowed and the applied voltage is lowered.

However, when looking at a cross-sectional view of this comb-shaped pattern, as shown in Figure 3, the range in the thickness direction where a sufficient electric field is applied to change the plane of polarization (range d in Figure 3, hereinafter referred to as d) is It is only a part near the surface. Therefore, if a groove-shaped comb-pattern electrode structure is used as shown in FIG. 4(a), d expands to the inside, and the polarization plane can change greatly even with the same electric field. Furthermore, if electrodes are provided on both sides as shown in FIG. 4(b), d doubles and the applied voltage can be reduced.

If the applied voltage can be reduced by the method described above, the control speed of the oscillation circuit can be increased, and the high-speed response of PLZT can be fully demonstrated. Therefore, the method of forming the electrodes becomes an important technology.

Photolithography is suitable for forming electrodes with complex patterns such as comb-like patterns, and grooves can be easily formed by combining this with chemical etching. For example, when the material is alumina, Toyo Sabimitsu Kogyo Co., Ltd.'s [Ceramic Etching] is an example. but,
BHHB was required for application to PLZT and was not adopted. The reason for the stiffness is that conventionally known etching solutions are highly corrosive and will etch the PLZT portion covered with photoresist, resulting in the problem of devitrification of the PIZT.

Therefore, the current common method is to perform grooving 1 by subjecting PLZT coated with photoresist to mechanical processing, typically using a dicing saw.

[Problems to be solved by the invention] When machining grooves to form groove-shaped electrodes, mechanical machining has problems with chips such as chipping and clutter of the sample, and because the holes are fully excavated one by one, there are problems especially on both sides. There is a problem in that it is unproductive in terms of time, such as when forming groove electrodes.

In addition, chemical etching, which is a known technique used for alumina, is suitable for mass production, but
If applied as is, there is a problem of devitrification of PLZT due to excessive g-erosion.

The object of the present invention is to apply photolithography techniques to the processing of PLZT electrodes. The object of the present invention is to provide a method that enables chemical etching without causing devitrification of T.

[Means for Solving the Problems] In order to achieve this object, the electrode forming method according to the present invention is a method of providing an electrode to lanthanum-modified lead zirconate titanate (pH'), which uses a photolithography technique. The method is characterized in that after a comb-shaped pattern is formed using the etchant, a groove is formed by chemical etching, and an electrode is affixed to form a groove-shaped electrode.

The present invention will be explained in detail below.

Pl, ZT is generally Pb++-x+1. ax(ZryT
! ++-y+)+-xz<0+ However, in the case of the present invention, all 10 component systems of the above formula can be applied.

First, a photoresist film is coated on the surfaces of Pl and ZT, and exposure and development are performed using a mask having a predetermined electrode pattern, so that only the patterned portions of the resist film are peeled off and the sample surface is exposed. The type of photoresist used at this time is determined by its durability against etching liquid and the degree of pattern integration. For example, when forming a full width of 100μm with 200μ1T11N■ using the etching solution described below, use the positive type and corrosion resistant 8Z1350J.
Nato is fine. In addition, when electroless plating is used for electrode application, it is necessary to consider durability against plating solutions and the like.

At this time, the thickness of the photoresist is preferably 1 to 1 μm. If it is thin, it will be corroded by the etching solution and will not function as a mask, and if it is thick, the adhesion to Pl and ZT will be poor and it will grow from the edges of the pattern during etching.

Is there a slight change in thickness depending on the groove depth? For example, 20μ
If it is less than m, it is sufficient to use a jug of 2 μm.

Next, the sample with the patterned resist film is placed in an etching solution. The etching solution may be a mixed aqueous solution of hydrofluoric acid and nitric acid. The concentration is particularly important, and the concentration is determined by the target groove shape and the corrosion resistance of the photoresist.

At this time, methods such as heating the etching solution, bubbling it, or stirring the etching solution may be used in order to improve the etching efficiency.

・The depth of the groove depends on the time of this chemical etching. Remove it from the etching solution and clean the etching solution with distilled water to terminate the corrosion reaction.

Next, an electrode is applied with the resist still attached, and finally the resist is peeled off to obtain a groove-shaped patterned electrode. The electrode may be provided by any method such as vacuum evaporation, sputtering, or electroless plating, and since etching is used, the anchor effect improves the resistance of the electrode to peeling off. Note that when electroless plating is used, the electrodes can be uniformly applied to the wall surfaces of the grooves, which improves the uniformity of the electric field. Furthermore, since the resist can be peeled off at the stage of catalyzing, it is easier than peeling off after attaching the electrode.

[Function] According to the present invention, the groove machining of the comb-shaped pattern becomes very simple and is suitable for mass production. Furthermore, when combined with electroless plating, the uniformity of the electric field improves, contributing to reducing the applied voltage and improving reliability.

[Example] (Example 1) Diameter 20 mm Thickness 0.51 mm Composition 9/65/35 (
D After thoroughly cleaning the PLZT wafer with distilled water and acetone, apply a positive photoresist using a spin coater.
Z1350J was coated to a film thickness of 2IJI11, and the full width was approximately 100JJI using an exposure machine using a mercury lamp.
11. A comb-shaped pattern with a groove interval of approximately 200 μm was constructed.

0 PLZT with patterned photoresist
．． It was immersed in a mixed aqueous solution of 47 molX hydrogen fluoride and 0.90% nitric acid, stirred every 2 minutes as if washing with a tap, and after about 15 minutes was taken out and thoroughly washed with distilled water.

The shape of the completed groove was as expected, with a full width of about 11001 J, a groove interval of about 200 μm, and a full depth of about 20 μm.

Gold spatter is applied with the resist attached to a thickness of approximately 1 μm.
A gold electrode was attached. It is thought that some electrodes were attached to the side walls of the groove due to the wraparound. Thereafter, the sample was ultrasonically cleaned in acetone, the resist was peeled off, and the target patterned groove electrode was obtained.

When we compared the driving voltages of an optical shutter fabricated in this manner and an optical shutter fabricated from the same wafer with non-groove type surface-deposited electrodes, we found that the latter was 160%
However, in the present invention, the driving voltage was reduced to 140 V.

(Example 2) P with diameter 20mm thickness 0.5+am composition 9/65/35
After thoroughly cleaning the LZT wafer with distilled water and acetone,
Positive photoresist AZ13 using a spin coater
A comb-shaped pattern with a groove width of about 90 IJlB and a groove interval of about 210 um was formed using an exposure machine using a mercury lamp.

Buttered photoresist, strike size P L
7. 0.47 mol of T kept at 60℃ in hot water!
Soak it in a mixed aqueous solution of 1.5 t of hydrogen fluoride and 0.904 t of nitric acid, stir every 2 minutes as if washing with a tap, and add about 1 t of hydrogen fluoride.
It was taken out after 5 minutes and thoroughly washed with distilled water.

The shape of the completed groove has a full width of approximately 100 μm and a groove spacing of approximately 2.
The groove depth was approximately 40JJ11, and the target groove shape could be obtained.

The resist was immersed in an aqueous solution of tin chloride and palladium chloride for 2 to 5 minutes each, and then tap-washed in acetone to remove the resist. Thereafter, electroless copper plating was applied to obtain the target patterned groove electrode. A cross-sectional view of this pattern is shown in FIG.

When we compared the driving voltages of an optical shutter fabricated in this manner and an optical shutter fabricated from the same wafer with non-groove type surface-deposited electrodes, we found that the latter was 160%
While v is necessary! The driving voltage was reduced to 20v.

[Effects of the Invention] According to the present invention, the groove machining process is simple and a large amount can be processed at once, so it is very effective for large-sized products and mass production. Furthermore, since electrodes can be applied while leaving the photomask, electroless plating can be used, which is a very advantageous method that improves the uniformity of the electric field.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a PLOT shutter in which groove-shaped electrodes are formed by electroless plating. FIG. 2 is a schematic diagram of a known comb pattern. FIG. 3 is a cross-sectional view of a PLZT shutter in which the comb-shaped electrodes shown in FIG. 2 are formed, and d represents the range where an electric field is applied to sufficiently rotate the plane of polarization. Figure 4 is a cross-sectional view of a groove-shaped electrode, where (a) is formed on one side and (b) is formed on both sides, indicating that d has increased compared to Figure 3. .

Claims (1)

[Claims] 1. In a method of providing electrodes to lanthanum-modified lead zirconate titanate (PLZT), a comb-shaped pattern is formed using a photolithography method, and then a fillet is formed by chemical etching to form an electrode. 1. A method for forming a groove-type electrode on PLZT translucent ceramic, the method comprising: imparting a groove-type electrode to a PLZT translucent ceramic. 2. The method for forming groove-shaped electrodes on PLZT translucent ceramics according to claim 1, wherein the electrodes are provided by electroless plating.