Mitsubishi Denki Kabushiki Kaisha

Junji Nakanishi

Satoshi Yamakawa

Nobuyoshi Hattori

First, a silicon germanium single-crystalline layer and a silicon single-crystalline layer are formed on a main surface of a bond wafer by epitaxy. The overall surface of the bond wafer is oxidized for forming a silicon oxide layer. Then, a base wafer is bonded to the bond wafer. The bond wafer and the base wafer bonded to each other are heated for reinforcing adhesion therebetween. Then, the bond wafer is removed by plasma etching with chlorine gas while making the silicon germanium single-crystalline layer serve as a stopper. Thereafter the silicon germanium single-crystalline layer is polished by chemical mechanical polishing to have a thickness suitable for forming a device. Thus implemented is a method of manufacturing an SOI substrate by bonding capable of employing a layer having a crystal state with small irregularity for serving as a stopper having selectivity for single-crystalline silicon and effectively using the stopper as a device forming layer.

SOI substrate and semiconductor device

Method of manufacturing SOI substrate and semiconductor device

In a linear sensor, a charge transfer part is disposed between a one-dimensional array of photodetectors and an overflow drain and includes a CCD having four or more transfer gates for each photodetector for transferring signal charges from the photodetector array in a direction of the photodetector array, transfer gates controlling charge transfer from the photodetectors to the CCD, and shutter gates for controlling charge transfer from the charge transfer part to the overflow drain. Each transfer gate is disposed between each photodetector and a prescribed one of the four or more transfer gates, and each shutter gate is disposed between the prescribed transfer gate and the overflow drain. The four or more CCD transfer gates are controlled by four or more phase driving clocks. Therefore, during charge transfer, at least three adjacent CCD transfer gates are all closed so that signal charges are drained from the photodetector into the overflow drain through the transfer gate in the middle of the three transfer gates without mixing the drained signal charges with the signal charges transferred. The charge drain operation is carried out during the charge transfer operation in the charge transfer part whereby the timing of opening the shutter gate can be set at an arbitrary time in the charge read cycle.

Method for driving a linear image sensor

Linear image sensor with shutter gates for draining excess charge

A solid state imaging element includes a plurality of photodetectors arranged in a two-dimensional array on a semiconductor substrate, first and second charge transfer circuits for transferring signal charges in a vertical direction and a horizontal direction, respectively, a plurality of transfer gates for controlling charge transfer from the photodetectors to the first charge transfer circuit, a scanner for controlling switching of the transfer gates, a plurality of bus lines connecting the transfer gates with the scanner, and a bus line breakage checking circuit. The bus line breakage checking circuit includes a plurality of transistors connected in series with respective bus lines, a test pad connected with the bus lines through the transistors, and a voltage applying pad for applying a voltage to control switching of the transistors. Therefore, the breakage of a bus line can be detected in a wafer test without actually operating the element, whereby time and money are saved.

Growing community of inventors

Itami, Japan

Junji Nakanishi