Abstract: A controller assigns a first plurality of blocks among a plurality of blocks provided in a non-volatile memory to a first area, assigns a second plurality of blocks to a second area, and assigns a third plurality of blocks to a third area. The controller uses each block assigned to the first area in a first mode, uses each block assigned to the second area in a second mode in which the number of bits of data written in each memory cell is larger than that in the first mode, and uses each block assigned to the third area in the first mode or the second mode. The controller writes data received from a host device to an area that corresponds to a designation from the host device out of the first area and the third area. The controller transcribes valid data written to the first area and the third area to the second area.

Abstract: A memory system includes a non-volatile memory and a controller that includes a first memory and is configured to write log data to the first memory, including a history of commands for controlling the memory system. An information processing system includes the memory system and an information processing device configured to store an expected value and to transmit a signal that instructs the memory system to stop when a value of the log data transmitted from the memory system does not match the expected value. The expected value and the transmitted value are determined based on the log data of the memory system.

Abstract: A memory system includes a non-volatile memory and a controller that includes a first memory and is configured to write log data to the first memory, including a history of commands for controlling the memory system. An information processing system includes the memory system and an information processing device configured to store an expected value and to transmit a signal that instructs the memory system to stop when a value of the log data transmitted from the memory system does not match the expected value. The expected value and the transmitted value are determined based on the log data of the memory system.

Abstract: A memory system includes a non-volatile memory and a controller that includes a first memory and is configured to write log data to the first memory, including a history of commands for controlling the memory system. An information processing system includes the memory system and an information processing device configured to store an expected value and to transmit a signal that instructs the memory system to stop when a value of the log data transmitted from the memory system does not match the expected value. The expected value and the transmitted value are determined based on the log data of the memory system.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory including a first storage area; and a memory controller which receives first data from a host device to access the nonvolatile memory, and causes the first storage area to store therein log data based on the first data.

Abstract: A storage device includes a secure region including a plurality of pages. Each of a plurality of pages includes a first storage region in which a plurality of data items is stored and a second storage region in which a plurality of identification data items corresponding respectively to the plurality of data items is stored.

Abstract: There is disclosed a method of slicing a semiconductor ingot in which the ingot is pressed against a moving wire. A thinner portion of the wire is used at the beginning of slicing to cut a portion of the ingot where the cutting length is shorter than a predetermined length, and a thicker portion of the wire is used when the cutting length becomes longer than the predetermined length. Subsequently, a thinner portion of the wire is used when the slicing approaches to the end and the cutting length becomes shorter than a predetermined length. A portion of the wire used in previous slicing is used as the thinner portion. Alternatively, the thinner portion is formed through use of a die. The slicing method makes it possible to cut the ingot into a plurality of wafers having a uniform thickness.

Abstract: A lapping apparatus and a method for effectively utilizing a regenerated abrasive fluid in the lapping process of works such as semiconductor wafers or quartz wafers without causing any damage such as scratches to the works.A work lapping method using a regenerated abrasive fluid prepared from a used abrasive fluid and a new abrasive fluid, which comprises the steps of preliminarily lapping a work using the regenerated abrasive fluid to a predetermined stock removal of the work, and finally lapping the preliminarily lapped work using the new abrasive fluid.

Abstract: An improvement is proposed in the method for the preparation of a magnetic recording medium by forming a magnetic recording layer of a magnetic alloy on the surface of a non-magnetic substrate plate of, e.g., silicon so as to impart the magnetic recording medium with improved CSS (contact-start-stop) characteristics still without affecting the magnetic recording density. The improvement can be obtained by subjecting the surface of the substrate plate, prior to the formation of the magnetic recording layer, to a surface-roughening treatment which is performed either by a dry-process such as plasma etching and reactive ion etching or by a wet-process of anisotropic etching by using an aqueous solution of sodium or potassium hydroxide as the anisotropic etching solution. In particular, the plasma etching or reactive ion etching is conducted in the presence of a particulate scattering source body of aluminum, etc.

Abstract: Proposed is a substrate of a magnetic recording medium in the form of an annular disk made from a single crystal of silicon which is imparted with greatly improved mechanical strengths to withstand mechanical shocks and high-velocity revolution. Different from conventional annular disks as formed by a mechanical working to form the outer contour and the circular center opening, the peripheral surfaces of the inventive annular disk are freed from the work-stressed surface layer by a chemical etching treatment undertaken after the mechanical working.

Abstract: The present invention provides a method of making a semiconductor substrate having an SOI structure by temporarily bonding together two wafers having different thermal expansion coefficients to allow thinning of at least one of the wafers by chemical and/or mechanical treatment(s) to reduce the risk of strain, separation, cracks to the wafers followed by one or more heat treating steps to fully bond the wafers together. The method can produce semiconductor substrate having an SOI structure which can provide a silicon layer thin enough to allow various integrated circuits, or TFL-LCD or the like to be formed.

Abstract: The present invention provides a semiconductor substrate which is formed by bonding wafers together by heat treatment without causing the substrate to be thermally damaged to have thermal strain, separation, cracks, etc. due to the difference in the thermal expansion coefficient of the wafers, and particularly a semiconductor substrate having an SOI structure which can provide a silicon film thin enough to allow various integrated circuits or TFT-LCD to be formed In the present invention, after wafers are bonded temporarily in a low temperature range, one of the wafers is made thin by chemical treatment, then the wafers were bonded fully by heat treatment in a temperature range (where the thermal expansion coefficient of the wafer are not affected) higher than the above low temperature range, and then said one wafer can be made thinner by mechanical grinding or polishing mechano-chemically.

Abstract: A bonded wafer enjoying high strength of bonding of component wafers thereof is produced by a method which comprises causing the surfaces for mutual attachment of two semiconductor wafers to be irradiated with an ultraviolet light in an atmosphere of oxygen immediately before the two semiconductor wafers are joined to each other. One of the two semiconductor wafers to be used for the bonded wafer optionally has an oxide film formed on one surface thereof. One of the component wafers of the bonded wafer is optionally polished until the component wafer is reduced to a thin film.

Abstract: A method for controlling the thickness of a single crystal thin-film silicon layer bonded on a dielectric substrate in a SOI substrate thereby effecting conversion of said single crystal silicon layer to a thin film is disclosed. To be more precise, said method comprises selectively and hypothetically dividing the entire surface of said single crystal silicon layer destined to undergo a chemical vapor-phase corrosion reaction for the sake of said conversion into necessary minute sections and, at the sametime, taking preparatory measurement of the thickness of said single crystal silicon layer in each of said minute sections, and effecting on each of said minute sections said conversion to a thin film by a chemical vapor-phase corrosion reaction adjusted in accordance with the measured thickness of layer. The conversion to a thin film is attained with the dispersion of thickness of the single crystal silicon layer controlled with high accuracy.

Abstract: A Si single crystal thin film is classified according to the thickness into several areas such that the areas where the thin film is thicker is made oxide layer-free and the areas where the thin film is thinner is covered with oxide layer. Then, oxidation is conducted so that the thicker the thin film the lower the Si interface becomes, utilizing the different growth rates of the oxide layer in these areas. The thin film surface with a resulting staircase configuration is then leveled by the subsequent polishing treatment. In other method, oxide layer is formed in such way that the areas with a thicker thin film thickness will have a thinner oxide layer and the areas with a thinner thin film thickness will have a thicker oxide layer, and oxidation is conducted such that the thicker the thin film the lower the Si interface becomes.

Abstract: A method of polishing a semiconductor wafer, wherein the semiconductor wafer bonded to a plate is polished to a desired thickness by pressing the semiconductor wafer against a rotating turntable side, and at the same time, a thickness regulating member, whose surface layer is made of a material slower to polish than the semiconductor wafer, is arranged on the plane of the plate to control the thickness of the semiconductor wafer. The matrix of the thickness regulating member is made of silicon and the surface layer facing said turntable is a silicon oxide film.

Abstract: A new method of preparing an exceedingly flat substrate for forming semiconductor devices having an SOI structure is disclosed.In this process at least a first wafer made of silicon single crystal is concavely warped beforehand. A second silicon single crystal wafer is bonded to the concavely warped side of the first wafer with an oxide film interposed between the first and the second wafers. Subsequently the wafers are subjected to polishing and/or etching so that the second wafer bonded is thinned into a thin film to prepare a substrate for forming semiconductor devices having a SOI structure.At this time the polishing and/or etching cause the bonded wafers to be warped convexly to offset the concavity of the first wafer, resulting in realization of a precisely flat substrate for forming semiconductor devices having an SOI structure.

Abstract: A process for producing an SOI-structured semiconductor device substrate has the steps of: reducing the diameter of the one Si-monocrystal wafer of two bonded polished Si-monocrystal wafers to be slightly smaller than that of the other Si-monocrystal wafer so that the width of the annular margin defined between the bonded surfaces of the Si-monocrystal wafers is uniform; then forming an annular polishing guard on the cylindrical surface of the one wafer and the margin of the other wafer, the polishing guard having a predetermined thickness and being made of a material providing a polishing speed lower under the same condition than the one wafer; and then polishing the one wafer so as to make it in thin film. The polishing guard provides an accurate thickness control of the resulting Si-monocrystal thin film, in particular, even at a few micrometers level.

Abstract: The invention provides a novel apparatus for the wet treatment, e.g. chemical etching treatment, of a plural number of wafer materials such as wafers of high purity silicon semiconductors. The apparatus comprises a liquid tub for containing the treatment liquid, e.g. etching solution, a pair of screw shafts horizontally held in the liquid tub in parallel with each other to be rotatable in the same direction at the same velocity to serve as a kind of screw conveyor and a traveling drum carriage mounted on the screw shafts as engaged with the threads of the shafts at the circular end plates so as to be rotated and transferred in the treatment liquid simultaneously as the screw shafts rotate.