JPH0234898B2 - UMEKOMIGATAHEIBANMAIKURORENZUNOSEIZOHOHO - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a method for manufacturing an embedded flat plate microlens, and in particular to a method for locally heating a substrate made of a quartz substrate, a silicon plate, etc. with controlled laser light. The present invention relates to a method of manufacturing an embedded flat microlens in which the refractive index is increased by increasing the refractive index.

(b) Technical background In recent years, with the rapid development of optical fibers,
It is well known that it is being widely applied to optical communications, optical information processing, etc. Therefore, there is a strong demand for the development of embedded flat microlenses and embedded flat microlens arrays that can efficiently couple a large number of optical fibers with other optical devices.

(c) Problems with conventional technology Conventionally, microlenses or microlens arrays have been produced using a special glass substrate using an ion exchange method or the like. However, this method required a considerable amount of time to manufacture and had the disadvantage that the numerical aperture (NA) of the lens could not be made very large. Microlenses and microlens arrays can also be fabricated using plastic molding methods, cellulose sand embedding methods, etc., but the former has disadvantages in terms of light loss, high NA, reliability, etc., while the latter has disadvantages due to the assembly method and the same method. There were problems such as monolithic integration on the board.

(d) Purpose of the Invention In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide a method for manufacturing an embedded flat microlens that can efficiently couple a large number of optical fibers with other optical devices. That is.

(e) Structure of the Invention The above object is to heat the silicon oxide film formed on the quartz substrate or silicon substrate by locally irradiating and heating the silicon oxide film formed on the quartz substrate or silicon substrate in germanium tetrachloride gas. This is achieved by a method for manufacturing an embedded flat microlens, which is characterized by introducing germanium into the surface of silicon oxide to locally form a region with a high refractive index.

(f) Embodiments of the Invention Examples of the method for manufacturing an embedded flat microlens according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of a quartz plate heated with a laser beam for explaining an embodiment of the method for manufacturing an embedded flat microlens according to the present invention;
b is a cross-sectional view of a microlens array formed on quartz, where 1 is a laser beam, 2 is germanium tetrachloride gas (GeCl ₄ ) gas, 3 is a quartz substrate, 4 is a temperature distribution, 5 is a refractive index distribution, and 6 is a microlens array. Lens refractive index distribution, 7 is germanium (Ge) concentration distribution.

In FIG. 1a, a quartz substrate 3 is fixed in a vacuum container (not shown), and while a gas containing a substance having a higher refractive index than the quartz substrate 3, such as GeCl ₄ gas, is flowed, the quartz substrate 3 in the vacuum container is The surface of the quartz substrate 3 is locally heated by irradiating the surface of the quartz substrate 3 perpendicularly with a laser beam 1 having a mode of TEM ₀₀ , for example, through windows (not shown) provided at opposing positions. At this time, in order to prevent the laser beam 1 from being scattered in the GeCl ₄ gas, increasing the spot size and reducing heating efficiency, the distance between the window and the quartz substrate 3 may be set to several tens of mm. desirable. By making the spot size of the laser beam 1 approximately equal to the diameter of the microlens and controlling its power and irradiation time according to the pressure inside the vacuum container, the maximum temperature within the above spot size is close to the melting point of the quartz substrate 3. Temperature distribution 4 can be realized. For example, the conditions are to increase the laser power to 5 to 10W.
The irradiation time should be 10 to 20 minutes, and the pressure of germanium tetrachloride gas should be 0.5 atm. As a result, Ge in an amount approximately proportional to the temperature distribution 4 described above is introduced from the thermally decomposed GeCl ₄ gas into the quartz substrate 3 by thermal diffusion, and a refractive index distribution 5 approximately proportional to the temperature distribution 4 is formed. Become. FIG. 1b shows an embedded flat microlens array in which the aforementioned embedded flat microlenses are aligned with high accuracy.

FIG. 2 is a cross-sectional view of a silicon plate heated with laser light, and b is a cross-sectional view of a microlens array formed on silicon, for explaining another embodiment of the method for manufacturing an embedded flat microlens according to the present invention. In the formed cross-sectional view, the same parts as in the previous figure are given the same reference numerals, 8 is a silicon substrate, and 9 is a silicon oxide (SiO ₂ ) film.

FIG. 2a is a cross-sectional view for explaining an embodiment in which a silicon substrate 8 having a silicon oxide film 9 deposited by a thermal oxidation method or a CVD method is used in place of the quartz substrate 3 described above. The laser beam 1 is irradiated by the same method as in the example, and Ge is locally introduced into the silicon oxide film 9 to form the refractive index distribution 5. At this time, even if Ge is introduced into the silicon substrate 8 under the silicon oxide film 9, it does not affect the subsequent results. FIG. 2b shows an embedded flat microlens array in which the aforementioned embedded flat microlenses are aligned with high accuracy. Furthermore, as shown in FIG. 3, after covering the surface of the silicon substrate 8 opposite to the surface on which the microlenses are formed with a resist film 10 and opening a window in the region facing the microlenses, the silicon substrate 8 is selectively removed. Remove the etching and insert the optical fiber 11 into this window area.
By inserting the microlens, the optical fiber 11 and the microlens can be combined easily and accurately without special alignment.

(g) Effect of the invention As is clear from the above explanation, according to the method for manufacturing an embedded flat plate microlens according to the present invention, microlenses and microlenses can be formed on a substrate by precisely controlling laser light. Since the manufacturing of the lens array and the coupling with the optical fiber can be performed easily and accurately, it greatly contributes to improving mass productivity and quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a quartz plate heated with a laser beam to form a microlens, and b is a cross-sectional view of a quartz plate heated with a laser beam to explain an embodiment of the method for manufacturing an embedded flat plate microlens according to the present invention. FIG. 2 is a cross-sectional view of a microlens array formed, and FIG. FIG. 3 is a cross-sectional view showing a microlens array formed on silicon, and FIG. In the figure, 1 is a laser beam, 2 is germanium tetrachloride (GeCl ₄ ) gas, 3 is a quartz substrate, 4 is a temperature distribution, 5 is a refractive index distribution, 6 is a microlens refractive index distribution, and 7 is a germanium (Ge) concentration. Distribution, 8 is silicon substrate, 9
10 is a silicon oxide (SiO ₂ ) film, 10 is a resist film,
11 indicates an optical fiber.

Claims (1)

[Claims] 1 Introducing germanium onto the surface of the quartz substrate or silicon oxide by locally irradiating and heating the silicon oxide film formed on the quartz substrate or silicon substrate with laser light in germanium tetrachloride gas. A method for manufacturing an embedded flat microlens, characterized by locally forming a region with a high refractive index.