JPS58211120A - Method for forming metallic pattern on light guide - Google Patents

Abstract

PURPOSE:To obtain a pattern which prevents the deterioration of the performance of a thin-film light guide, by forming a metallic blank material film on the light guide only where a metallic film pattern is formed and at its circumference, and covering the metallic blank material film with a resist film except at a part to be etched and then etching the metallic film. CONSTITUTION:A thin Ti film is vapor-deposited on the X.Z plane of a dielectric substrate 1 of LiNbO3 single crystal, etc., which is cut along an Y axis and then heated at about 1,000 deg.C for five hours to form a thin-film light guide 2. After the surface of the light guide 2 is cleaned by an ultrasonic wave and then dried, a metallic layer 6 of Al, etc., is formed only at a pattern generation part for providing a comb-shaped electrode 5. The resist film 7' is formed over the layer 6 and the entire surface of the light guide and then a resist pattern 7' is formed on only the resist on the layer 6 by a lithography method. Plasma etching is carried out in an atmosphere of gaseous CCl4 to form a metallic pattern 6' and resist films 7 and 7' are peeled with acetone, etc. Thus, damage due to the etching of the light guide 2 is prevented to obtain an optical switching element, etc., without deteriorating its performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming turns made of metal or the like in an optical waveguide in a guiding waveguide used in an optical switching device or the like.

Conventionally, as shown in FIG. 1, an optical waveguide has been known in which a thin film waveguide 2 made of a titanium (Ti) film or the like is formed on a dielectric substrate F1, and light is introduced into the thin film waveguide 2 using an incident prism 3. It is being In order to use this optical waveguide as an optical switching element f etc., the light beam propagating through the thin film waveguide 2 is deflected and emitted from the exit prism 4. As one means for this purpose, a comb-shaped electrode 5 is formed in the thin-film waveguide 2F-, and a +1 surface wave is excited in the thin-film waveguide 2 by applying a field to the comb-shaped electrode 5. It has been practiced to polarize the light beam by Bragg diffraction.

In this case, in order to form a metal pattern such as the comb-shaped electrode 5 on the thin film waveguide 2, a metal whose pattern is to be formed is deposited on the entire surface of the thin film waveguide 2, a resist pattern is formed by phosphorography, and then etched. This process is based on the process of printing the desired metal pattern.

This conventional metal pattern forming method will be explained in more detail with reference to FIG. A metal layer 6 of aluminum or the like is deposited on the entire surface by vacuum deposition or the like. Further, as an upper layer of this metal layer 6, a resist film 7 is applied using a spinner or the like as shown in (C), and a resist pattern 7' is formed by phosphorography as shown in (d). In this state, the metal layer 6 is etched with an etching solution to form a metal pattern 6' having resist film turns 7' on the top.Finally, when the resist pattern 7' is peeled off, four sieves formed by the metal groove turns 6' are formed. A mold electrode 5 is produced at the very beginning of the thin film waveguide 2.

However, according to this method, Fig. 2 (C) to (d)
As shown in the process shown in FIG. In the case of etching, since it acts chemically and physically on the thin film waveguide 2, it has adverse effects such as roughening the surface condition of the thin film waveguide 2 and changing the refractive index of the thin film waveguide 2. There are problems such as destruction of the thin film waveguide 2 and low F of light transmission.

An object of the present invention is to solve the above-mentioned problems and provide a method for forming a pattern of metal or the like on a leading waveguide without adversely affecting the thin film waveguide.
X* L waveguide 1. In the case of forming a pattern such as a metal coating on a substrate, a step of providing a material coating for forming a pattern on and in the vicinity of the portion where the pattern is to be formed, and a step of forming a material coating with the material coating and a thin I-conductor Wave path I
- a step of coating the entire surface of the material film with a resist film; a step of etching the material film of the thin 11-wire waveguide 1 with an etching solution; iIII remaining in -
This method is characterized by comprising a step of removing the registration mark.

The present invention will be explained in detail based on the embodiment shown in FIG. In addition, in FIG. 3, the material shown in FIG. 2 and the material shown in FIG.

Similarly to FIG. 2(a), the embodiment shown in FIG. 3(a) uses an optical waveguide in which a thin film waveguide 2 is formed on the (plate 1).This optical waveguide is cut along the Y axis. A single crystal of lithium niobate (LiNb03) was
A titanium film was deposited on the x-Z plane to a thickness of 250 mm on a substrate 1 having a size of 1 inch in the Z-axis direction and 1 mm in the Y-axis force direction, and was heated at about 1000°C for 5 hours to remove titanium. A thin film waveguide 2 having a higher refractive index than the substrate 1 is formed by thermal diffusion. After the surface of the thin film waveguide 2 is ultrasonically cleaned, it is sufficiently dried in ethanol vapor. Furthermore, (
As shown in b), a metal layer 6 made of aluminum or the like is formed to a thickness of approximately 2000 mm using the electron beam red-blue method only in the patterned area for providing the comb-shaped electrode 5 and in the vicinity thereof, for example, in a 10 mm x 0 mm area. Cover.

Next, as shown in (C), press the spinner etc.
II! 7 is coated on the entire surface of the metal layer 6 and the thin film waveguide 2 to a thickness of about IILm, and after pre-baking at 90°C for 30 minutes, a single layer of resist 1 on the metal layer 6 is applied as shown in (d). A resist pattern 7' of comb-shaped electrodes 5 having a pitch width of 2 gm is formed by phosphorography using a mask aligner. Bost-hake is then carried out at a temperature of approximately 120°C for 20 minutes, and the metal layer 6 is plasma etched in carbon tetrachloride (CCρ4) scum for 2 minutes as shown in (e) to form the metal pattern 6'. and finally acetone (CH,C0CH) as shown in (f)
The resist film 7 is peeled off, and a comb-shaped electrode 5 made of metal B hair is obtained on the thin film waveguide 2].

In this way, in this embodiment, the metal layer 6 is formed only in the part where the pattern is to be created, and the resist film 7 is used as a protective layer in the part where the 1, 11 patterns are to be created, and the etching is performed, so that the part where the pattern is not created is etched. Damage to the thin film waveguide 2 can be prevented. Moreover, it is effective not only when creating a metal pattern 6' but also when creating a non-metal pattern such as silicon dioxide' (Si02).

As explained above, according to the method for forming a metal pattern on an optical waveguide according to the present invention, a metal pattern can be formed on the thin film waveguide without the etching solution coming into contact with the thin film waveguide. Therefore, the performance of the thin film waveguide is not deteriorated due to the influence of the etching solution, and an optical switching device or the like with good performance can be realized. Further, since the metal layer on the thin film waveguide is provided only in the area where the pattern is formed, the amount of thin film material can be saved.

[Brief explanation of the drawing]

Figure 1 is a perspective view of an optical switching element using an optical waveguide, Figures 2 (a) to (f) are explanatory diagrams of a conventional method for forming patterns of metal, etc. on an optical waveguide, and Figure 3 (a). ~(f)
FIG. 2 is an explanatory diagram of a method of forming a pattern of metal or the like on an optical waveguide according to the present invention. 1 is a substrate, 2 is a thin film waveguide, 5 is a comb-shaped electrode, 6 is a metal layer, 6' is a metal pattern, 7 is a resist film, and 7' is a resist pattern. Patent applicant Canon Co., Ltd. 3fl (G)

Claims (1)

[Claims] 1. In the case of forming a pattern such as a metal coating on a thin film waveguide, a step of providing a material coating for forming a pattern on a portion of the thin film waveguide where the pattern is to be formed and in the vicinity thereof; a step of coating the entire surface of the material film and the thin film waveguide with a resist film; a step of forming a resist pattern on the resist film on the material film; a step of etching the material film with an etching solution; and a step of etching the material film with an etching solution. A method for forming a pattern of metal or the like on an optical waveguide, comprising the steps of removing the resist film remaining on the path. 2. A method of forming a pattern of metal or the like on an optical waveguide, in which the material film forming the pattern is a metal film of aluminum or the like. 3. A method of forming a pattern of metal or the like on a leading waveguide in which the material film forming the pattern is a film of silicon dioxide.