Optical waveguides – Planar optical waveguide
Reexamination Certificate
1999-11-09
2002-04-09
Healy, Brian (Department: 2874)
Optical waveguides
Planar optical waveguide
C385S130000, C385S131000, C385S132000, C385S014000, C385S012000, C385S049000, C385S031000, C385S032000
Reexamination Certificate
active
06370306
ABSTRACT:
TECHNICAL FIELD
This invention relates to an optical waveguide probe for observing sample geometry utilizing an atomic force between substances and measuring optical property of a microscopic region of a sample through a probe formed by an optical waveguide, and to a method for manufacturing the same.
BACKGROUND OF THE INVENTION
At present, in the scanning near field optical microscopes (hereinafter abbreviated as SNOM) measurement is made of sample optical characteristics and geometry by causing a tip-sharpened probe of an optical medium to approach a measurement sample at a distance of less than light wavelength. There is proposed an apparatus, as one of such apparatuses, wherein a linear-formed optical fiber probe vertically held close to a sample at its tip is horizontally vibrated relative to a sample surface, so that a change in amplitude of vibration caused due to shear forces at the sample surface and probe tip is detected by irradiating laser light to the probe tip and detecting a change in a shadow thereof, wherein the sample is moved by a fine movement mechanism to maintain the amplitude constant whereby the spacing between the probe tip and the sample surface is kept constant to detect sample geometry and measure sample light transmission from an intensity of an input signal to the fine movement mechanism.
Also, there is proposed a scanning near field atomic force microscope which uses a hook formed optical fiber probe as a cantilever for the atomic force microscope (hereinafter abbreviated as AFM) to perform AFM actuation, and simultaneously illuminates laser light through an optical fiber probe tip onto a sample to thereby detect sample geometry and measure sample optical properties (No. 174542/1995).
FIG. 34
is a structural view showing an optical waveguide probe of a conventional example. This optical waveguide is covered over its periphery by a metal film coating
102
. Also, a probe needle portion
103
is sharpened, and the probe needle
103
has an aperture
104
at its tip.
On the other hand, in AFMs utilized as fine region geometrical observing means, utilized broadly are micro-cantilevers of silicon formed by a silicon fabrication process or silicon nitride.
However, there has been a problem in that the optical fiber probe used in a SNOM is manufactured in processes having many steps requiring manual operation with an optical fiber as a material so that mass producibility is low and the shapes such as tip diameter and tip angle are uneven. Also, although high speed scanning control requires an increase in resonant frequency, because the optical fiber itself is used as a cantilever spring material, the spring portion if shortened in order to increase the resonant frequency has an increased spring constant. Also, there has been the problem that the optical fiber is of a thin and long filamentous material and difficult to handle. Also, although the arrangement with a plurality of optical probes enables high speed observation without requiring high speed scanning sweep of a sample surface, the optical fiber probe is manufactured one by one by manual operation and is not suited for a structure having a plurality of probes arranged on the same substrate, i.e., an array form.
On the other hand, the micro-cantilever used in an AFM is high in resonant frequency and high in mass producibility with reduced variation, and possesses the advantages that it is even in mechanical properties such as spring constant and resonant frequency and is easy to handle. However, there has been the problem that it is impossible to conduct light illumination and light detection at the tip portion required in the SNOM.
Also, samples with large steps such as biological samples and polymer samples are considered within the SNOM application scope. However, the micro-cantilever probe needle used in the conventional AFM is as short as approximately
10
microns and it is difficult to measure a sample with large steps. Furthermore, these samples in many cases require measurement in a liquid. However, the AFM micro-cantilever is a cantilever in a plate form and accordingly it is difficult to perform measurement in a liquid.
Therefore, this invention has been made in view of the above, and it is an object to provide an optical waveguide probe which fulfills conditions of excellent mass producibility and eveness, small spring constant, ease of handling, ease of use in a liquid, capability of light illumination and detection, and capability to be arrayed with ease. Also, it is another object to provide a manufacturing method for manufacturing such an optical waveguide probe.
DISCLOSURE OF THE INVENTION
This invention is characterized in that, in an optical waveguide probe having an optical waveguide sharpened at a probe needle portion formed in a hook form and a substrate supporting the optical waveguide, the optical waveguide is characterized in that the optical waveguide is overlaid on the substrate and formed integrally therewith. The optical waveguide formed of a dielectric material is used.
Also, according to the invention, in an optical waveguide probe having an optical waveguide sharpened at a probe needle portion formed in a hook form, a substrate supporting the optical waveguide and a metal film covering the optical waveguide, the optical waveguide characterized in that the optical waveguide is overlaid on the substrate and formed integrally therewith and the probe needle portion of the optical waveguide has at a tip an aperture covered over by the metal film. The optical waveguide is formed of a dielectric. Also, the optical waveguide has a metal film deposited over a dielectric for light transmission.
On the other hand, a method for manufacturing an optical waveguide probe, comprises: a process of forming a mold for embedding the optical waveguide in a substrate, a process of depositing the optical waveguide, a process of separating the optical waveguide along the mold for embedding the optical waveguide, a process of separating the optical waveguide from the substrate.
Of the manufacturing process for an optical waveguide probe, the process of forming a mold for embedding the optical waveguide is any of an isotropic dry etching process or wet etching process using, as etching mask, photo resist having a thickness distribution having been exposed using a photo mask with a gradation, an anisotropic dry etching process using, as an etching mask, photo resist having a thickness distribution exposed using a photo mask with a gradation, an isotropic wet etching or dry etching process utilizing etching undercut to the underneath of an etching mask, a multi-staged anisotropic wet etching process to a silicon substrate using an etching mask formed stepwise with at least two steps, and an anisotropic wet etching process to a silicon substrate.
Also, the process of depositing the optical waveguide in the mold for embedding the optical waveguide is a process of depositing a dielectric material corresponding to the cladding, depositing a dielectric material relatively greater in refractive index than the cladding corresponding to the core, patterning the core, and further depositing a dielectric material corresponding to the cladding. The core patterning is conducted by photolithography using electro-deposition resist.
The process of separating the optical waveguide along the mold for embedding the optical waveguide is a polishing process for depositing a dielectric material in the mold for embedding the optical waveguide, thereafter planarizing by embedding a resin material in a recess formed in a portion of the mold for embedding the optical waveguide, and separating the optical waveguide by polishing to an original substrate surface or deeper than the original substrate surface. Also, the process of patterning the optical waveguide into a probe shape is performed, using electro-deposition resist as etching mask, by an anisotropic dry etching or wet etching process and an isotropic dry etching and wet etching process.
Th process of separating the optical waveguide probe from the substrate
Chiba Norio
Ichihara Susumu
Kasama Nobuyuki
Kato Kenji
Mitsuoka Yasayuki
Adams & Wilks
Healy Brian
Seiko Instruments Inc.
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