Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-11-24
2003-04-01
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S214100
Reexamination Certificate
active
06541755
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a probe used for an optical memory such as an optical disc, an optical card, an optical tape, or the like, to which information is recorded, from which information is reproduced, and from which information is erased, using light, and, in particular, to a near field optical probe which generates the optical near field and detects scattered light generated through the optical near field and a manufacturing method thereof.
2. Description of the Related Art
In an optical memory, which has been put to practical use, a laser spot, obtained from converging laser light to the diffraction limit, is caused to be incident on a recording medium. At this time, information is recorded on the recording medium as a result of thermal and magnetic modulation being performed on a recording layer of the recording medium. Further, by detecting the intensities of reflected light modulated by record bits, the information is reproduced. In such information recording means, the recording density of the recording medium is approximately determined by the laser wavelength. In order to cope with a recent increase in an information amount processed in various types of information apparatuses such as computers and so forth, a large-capacity memory which achieves a recording density which is obtained as a result of the diffraction limit being exceeded has been demanded. As a promised next-generation large-capacity memory such as that mentioned above, an optical memory on which information recording, reproducing and erasing are performed using the optical near field was proposed. Examples thereof will now be described.
(1) ‘Near Field Optics and Its Application to Optical Memory,’ a thesis journal of the Institute of Electronics, Information and Communication Engineers, C-I, Vol. J81-C-I, No. 3, Pages 119-126, March, 1998, proposes a device in which a two-dimensional aperture row is formed in a silicon substrate using a semiconductor-plane-process technique, and the optical near fields are generated on the apertures by light which has been incident on the top surface of the silicon substrate. Further, this literature suggests a possibility of integration with a photodetector array.
(2) Japanese Laid-Open Patent Application No. 9-198830 discloses that, in a high-density recording apparatus using the optical near field, in order to stably generate the optical near field in proximity to a recording medium, a high-density recording is performed using a slider in which a circular-cone-shape through hole having an aperture is provided.
Thus, the device in which the two-dimensional aperture row is formed in the silicon substrate using the semiconductor-plane-process technique, and the optical near fields are generated on the apertures by light which has been incident on the top surface of the silicon substrate, was proposed. When a photodetector is integrated into such a device, it is possible to miniaturize such a near field optical probe, and to improve efficiency in detection because it is possible that scattered light and so forth generated through the optical near field can be received in the proximity.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a specific structure and a manufacturing method of a near field optical probe having an arrangement in which an aperture for generating the optical near field which was proposed and a semiconductor photodetector (photodiode: PD) are integrated so as to be combined.
Another object of the present invention is to provide a near field optical probe which can perform a light-detecting operation stably at high speed while generating the optical near field from an aperture.
Another object of the present invention is to provide a manufacturing method of a near field optical probe in which, when an arrangement in which a through hole is surrounded by a ring-shaped high-concentration impurity region along the direction of the through hole is produced, it is easy to form the high-concentration impurity region to a deep portion of the through hole.
Another object of the present invention is to simplify a manufacturing method of a near field optical probe in which a metal film for shading necessary for generation of the optical near field and a terminal which is a component of a photodetector are formed simultaneously.
In a near field optical probe, according to the present invention, a through hole having an aperture is provided in a semiconductor photodetector including at least a first-conductive-type high-concentration impurity layer, a first-conductive-type low-concentration impurity layer and a second-conductivity-type impurity-introduced region.
In this arrangement, by integration of the aperture for generating the optical near field and the semiconductor photodetector (photodiode: PD), which integration has been proposed in the related art, it is possible to miniaturize the near field optical probe and to remarkably improve detection of diffused light generated through the optical near field.
A method for manufacturing the above-described near field optical probe, according to another aspect of the present invention, in which probe the through hole having the aperture is provided in the semiconductor photodetector including at least the first-conductive-type high-concentration impurity layer, the first-conductive-type low-concentration impurity layer and the second-conductivity-type impurity-introduced region, comprises the steps of:
a) forming the second-conductive-type impurity-introduced region in the surface of the first-conductive-type low-concentration impurity layer of a semiconductor substrate having the first-conductive-type high-concentration impurity layer and first-conductive-type low-concentration impurity layer;
b) forming the through hole, which passes through the first-conductive-type high-concentration impurity layer and first-conductive-type low-concentration impurity layer, from the side of the first-conductive-type high-concentration impurity layer, after the step a); and
c) forming the aperture in the second-conductive-type impurity-introduced region, after the step b).
In this method, it is possible to cope with various variations in conditions at the time of forming the through hole and manufacture the above-described near field optical probe.
A method for manufacturing the above-described near field optical probe, according to another aspect of the present invention, in which probe the through hole having the aperture is provided in the semiconductor photodetector including at least the first-conductive-type high-concentration impurity layer, first-conductive-type low-concentration impurity layer and second-conductivity-type impurity-introduced region, comprises the steps of:
a) forming the through hole, which passes through the first-conductive-type high-concentration impurity layer and first-conductive-type low-concentration impurity layer, from the side of the first-conductive-type high-concentration impurity layer; and
b) forming the second-conductive-type impurity-introduced region in the surface of the first-conductive-type low-concentration impurity layer of a semiconductor substrate having the first-conductive-type high-concentration impurity layer and first-conductive-type low-concentration impurity layer, after the step a).
In this method, it is possible to prevent conditions from being complicated due to differences in conductive-type at the time of forming the through hole, and manufacture the near field optical probe stably.
In a near field optical probe, according to another aspect of the present invention, in which probe a through hole having an aperture is provided in a semiconductor photodetector including at least a first-conductive-type high-concentration impurity layer, a first-conductive-type low-concentration impurity layer and a second-conductivity-type impurity-introduced region,
the second-conductive-type impurity-introduced region is provided separately from the aperture.
In this arrangement, becau
Fujita Shunsuke
Kourogi Motonobu
Ohtsu Motoichi
Le Que T.
Luu Thanh X.
Ricoh & Company, Ltd.
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