Naoetsu Electronics Co., Ltd.

Tsutomu Satoh

Hisashi Ohshima

Kouichi Nishimaki

A method of fabricating a silicon semiconductor discrete wafer while dressing the grinding wheel is disclosed that assures excellent finishing accuracy and productivity. The dressing of the grinding wheel includes mixing air and grinding water from a surface grinding process including semiconductor chips lapped with abrasive grains having a count of at least &num;2000 and no more than &num;6000 and jetting the mixed air and grinding water as minute water drops back onto the surface of the grinding wheel during grinding of a wafer. Both cut surfaces are ground to a predetermined thickness with the dressed grinding wheel (via a surface grinding machine). The processing surface is wet-etched as the final processing.

Method for fabricating silicon semiconductor discrete wafer

The problem to be solved by the present invention is providing a production method capable of adjusting a dislocation density freely to a required dislocation density level for a discrete structure substrate. According to the present invention, when producing a discrete structure substrate generally said to have a low level dislocation density in which an average dislocation density is 5000 pieces/cm.sup.2, diffusing a wafer after determining its thickness so as to meet required dislocation density level, a wafer thickness is adjusted within a specified range before diffusion is carried out.

Production method for a discrete structure substrate

Wet etching method and apparatus in which a wafer is processed so as to have a good flatness by making uniform a travel distance and a traveling velocity of an arbitrary point on a wafer surface relative to an etching solution, while rotating the wafer in the etching solution. An etching solution vessel comprises a pair of walls parallel to a plane of rotation of a wafer; and walls of curved surfaces, which intersect the pairs of walls at a right angle, and whose centers of curvature are the same, and which are spaced apart from each other along a radius of curvature with a distance of d therebetween; the etching solution is fed from a lower part of the vessel; and a flow velocity of the etching solution is adjusted at an arbitrary point between the pair of curved surfaces just before a stream of the solution contacts with a wafer rotating in the etching solution so that the flow velocity is a velocity (r.omega.), which is obtained by multiplying a distance r between the center of curvature and the arbitrary point with an angular velocity .omega. of the wafer or an approximation thereof.

Wet etching method for silicon semiconductor wafer

A method of fabricating a silicon semiconductor discrete wafer is disclosed that assures excellent finishing accuracy and productivity. The method for fabricating a discrete wafer having a double-layer structure including an impurity diffused layer at one side and an impurity non-diffused layer at the opposite side includes cutting a wafer, having one of the impurity diffused layers formed on both surfaces of the silicon semiconductor wafer and having an oxide film formed on the surface of the diffused layer, into two pieces at the center of thickness with an ID saw slicing machine. Then, both surfaces of the cutting surface are ground to a predetermined thickness with a surface grinding machine, and the grinding surfaces are lapped with abrasive grains having a count of at least #2000 and no more than #6000. The processing surface is wet-etched as the final processing.

This invention relates to a process and an apparatus for making a substrate of a semiconductor of a monolithic silicon wafer, or the like, for use as a discrete element such as a transistor, diode, or the like. In particular, the invention is directed to re-slicing the silicon wafer into two further pieces, to dope impurity diffused layers on both sides but not to provide any impurity diffused layer in the core portion of the silicon wafer. The re-slicing process is performed from substantially the center portion of its core thickness of the wafer so as to provide each re-sliced surface as a plain surface without any impurity diffused layer and for doping a further new impurity diffused layer, so as to obtain two pieces of a substrate as discrete elements simultaneously from one piece of the wafer by the re-slicing process and apparatus of the invention.

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Niigata-ken, Japan

Tsutomu Satoh