Tdk Corporation

Semiconductor Energy Laboratory Co., Ltd.

Nobuo Furukawa

Masaaki Hiroki

Michio Arai

Takeshi Fukada

Yukio Yamauchi

Masaaki Ikeda

Naoya Sakamoto

Kazushi Sugiura

Mitsufumi Kodama

Ichirou Takayama

Akihiro Takeda

Kazushi Tachimoto

Yoshiki Ohta

Hideya Sakamoto

A piezoelectric element includes a piezoelectric body layer, a first electrode, a second electrode, a third electrode, and a conductor. The piezoelectric body layer has rectangular first and second principal surfaces opposing each other, and includes a piezoelectric material. The first electrode is provided on the first principal surface. The second electrode is provided on the first principal surface in such a way that the second electrode is separated from the first electrode. The third electrode is provided on the second principal surface in such a way that the third electrode opposes the first electrode. The conductor is connected to the second electrode and the third electrode. The first electrode has a round corner being rounder than a corner part of the piezoelectric body layer when seen in an opposing direction of the first and second principal surfaces.

Piezoelectric element

A piezoelectric element includes first and second electrodes, a first piezoelectric body layer, and a plurality of first through-hole conductors. The first and second electrodes oppose each other. The first piezoelectric body layer is disposed between the first electrode and the second electrode. The plurality of first through-hole conductors penetrates the first piezoelectric body layer and is connected to the first electrode and the second electrode. When seen in an opposing direction of the first and second electrodes, the plurality of first through-hole conductors is arrayed in a matrix.

A powder sensor includes a piezoelectric element, an oscillator circuit, a first square wave signal generator, a second square wave signal generator, and a phase judgment circuit. The oscillator circuit applies to the piezoelectric element an output signal having a frequency equal to or near a resonance frequency of the piezoelectric element. The first square wave signal generator generates a first square wave signal by converting a terminal voltage of the piezoelectric element. The second square wave signal generator generates a second square wave signal that transits from an initial level to a detection level when the first square wave signal rises or falls in a detection period and that does not transit outside of the detection period. The detection period is a part of each cycle of the output signal of the oscillator circuit. The phase judgment circuit determines phase of the second square wave signal.

Powder sensor

A powder sensor includes a piezoelectric element, an oscillator circuit, a phase determination circuit, and a powder presence/absence determination circuit. The oscillator circuit applies to the piezoelectric element an output signal having a frequency equal to or near a resonance frequency of the piezoelectric element. The phase determination circuit determines phase of a terminal voltage of the piezoelectric element relative to phase of the output signal from the oscillator circuit. The powder presence/absence determination circuit determines that powder is absent if the phase determination circuit determines, n consecutive times (where 'n' is an arbitrary integer satisfying n&#x2267;2), that the phase of the terminal voltage of the piezoelectric element, relative to the phase of the output signal from the oscillator circuit, satisfies a predetermined condition.

An image sensor (10) has a substrate (1), an active layer (3') having a source region and a drain region placed on said substrate (1), a gate insulation layer (4') placed on said active layer, and a gate electrode layer (5') on said gate insulation layer (4'). The active layer (3') is produced by the steps of producing amorphous silicon layer by using disilane gas (Si.sub.2 H.sub.6) through Low Pressure CVD process, and annealing said layer at 500.degree.-650.degree. C. for 4-50 hours in nitrogen gas atmosphere. The gate insulation layer (4') is produced through oxidation of the surface of the active layer at high temperature around 900.degree.-1100.degree. C. The oxidation process at high temperature improves the anneal process and improves the active layer. Thus, an image sensor with uniform characteristics is obtained with improved producing yield rate.

Method of making a semiconductor image sensor device

A MOS-FET transistor is produced on a substrate made of glass which has a non single crystal semiconductor film (2'). The average diameter of a crystal grain in said film is in the range between 0.5 times and 4 times of thickness of said film, and said average diameter is 250 .ANG.-8000 .ANG., and said film thickness is 500 .ANG.-2000 .ANG.. The density of oxygen in the semiconductor film (2') is less than 2.times.10.sup.19 /cm.sup.3. A photo sensor having PIN structure is also produced on the substrate, to provide an image sensor for a facsimile transmitter together with the transistors. Said film (2') is produced by placing amorphous silicon film on the glass substrate through CVD process using disilane gas, and effecting solid phase growth to said amorphous silicon film by heating the substrate together with said film in nitrogen gas atmosphere. The film (2') thus produced is subject to implantation of dopant for providing a transistor. The film thus produced has high mobility which provides high speed operation of a transistor, and low threshold voltage of a transistor.

Non-single crystal semiconductor device with sub-micron grain size

A MOS-FET transistor is produced on a substrate made of glass which has a non single crystal semiconductor film (2'). The average diameter of a crystal grain in said film is in the range between 0.5 times and 4 times of thickness of said film, and said average diameter is 250 .ANG.-8000 .ANG. , and said film thickness is 500 .ANG.-2000 .ANG.. The density of oxygen in the semiconductor film (2') is less than 2.times.10.sup.19 /cm.sup.3. A photo sensor having PIN structure is also produced on the substrate, to provide an image sensor for a facsimile transmitter together with the transistors. Said film (2') is produced by placing amorphous silicon film on the glass substrate through CVD process using disilane gas, and effecting solid phase growth to said amorphous silicon film by heating the substrate together with said film in nitrogen gas atmosphere. The film (2') thus produced is subject to implantation of dopant for providing a transistor. The film thus produced has high mobility which provides high speed operation of a transistor, and low threshold voltage of a transistor.

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Tokyo, Japan

Nobuo Furukawa