Abstract: This invention provides a semiconductor device including a silicon layer, an insulating layer formed on the silicon layer, a first semiconductor device formed on the insulating film to convert light into an electric signal, and a second semiconductor device formed on the insulating film, wherein a silicon region is formed in the silicon layer to shield the second semiconductor device from light, and a through hole extending through the silicon layer except for the silicon region to input light to the first semiconductor device is formed in that portion of the silicon layer corresponding to the lower portions of the first and second semiconductor devices.

Abstract: A semiconductor memory includes a plurality of memory cells which are arranged in a matrix and respectively store data, a plurality of bit lines and a plurality of word lines, connected to the plurality of memory cells, for performing read/write access of data to the memory cells, and a test circuit. In the test circuit, an external terminal sends test data and expected value data written in the memory cells. A simultaneous write circuit simultaneously writes the test data from the external terminal in the plurality of memory cells connected to a selected word line. A simultaneous comparison circuit simultaneously compares the test data written in the plurality of memory cells connected to the selected word line with the expected value data supplied from the external terminal in correspondence with the selected word line.

Abstract: A memory device which employs multilevel memory cells has a basic arrangement in which a write device writes multilevel information corresponding to binary data of plural bits in the memory cells and a readout device outputs binary data of plural bits representing the multilevel information read out of the memory cells. The memory device includes a multilevel detector for detecting the information of the memory cells at one time and reference level generator for generating reference levels therefor, thereby permitting the reduction of the bit area of each memory cell and increased speed during the operation of the memory device.

Abstract: In a semiconductor memory, a memory cell array is divided into a plurality of sub arrays in a direction perpendicular to word lines. In each sub array sub word lines and bit lines are disposed to intersect each other and memory cells are disposed at all their intersections. Two different sub arrays constitute a unit cell array. The sub word line connected to a cell transistor in one of or the first the sub arrays of the unit cell array is connected to a first main word line and a second main word line which is not connected to the cell transistor in the first sub array is passed therethrough for connection with the sub word line of the other or second sub array in the unit cell array.

Abstract: In addition to a main memory device a spare memory device is provided. Both memory devices utilize word wires in common which are arranged to constitute matrix circuits together with groups of bit lines. When a bit error is contained in data read out from the main memory device, a correction circuit correcting the error and a register for storing the error are provided. An output of the register is used to switch a bit line from which the error has been detected to a corresponding bit line of the spare memory device.

Abstract: A semiconductor memory device comprises at least one word line, a plurality of bit lines extending across the word line, a data memory cell unit including a plurality of data memory cells connected between the word line and the bit lines for storing information, a plurality of first extra bit lines corresponding to first groups of the bit lines, each of which has k bit lines (k is an integer), and extending across the word line, a plurality of first extra memory cells connected between the word line and the first extra bit lines for storing first checking information with respect to the first groups of the bit lines, a plurality of second extra bit lines corresponding to second groups of the bit lines, each of which group has m bit lines (m is an integer), and extending across the word line, a plurality of second extra memory cells connected between the word line and the second extra bit lines for storing second checking information with respect to the second groups of the bit lines, an error detection circui