In an embodiment, a method includes: performing a self-limiting process to modify a top surface of a wafer; after the self-limiting process completes, removing the modified top surface from the wafer; and repeating the performing the self-limiting process and the removing the modified top surface from the wafer until a thickness of the wafer is decreased to a predetermined thickness.

A polishing composition for use in polishing an object to be polished, which comprises abrasive grains, a dispersing medium, and an additive, wherein the abrasive grains are surface-modified, the additive is represented by the following formula 1: ##STR00001##
wherein in the formula 1, X.sub.1 is O or NR.sub.4, X.sub.2 is a single bond or NR.sub.5, R.sub.1 to R.sub.5 are each independently a hydrogen atom; a hydroxy group; a nitro group; a nitroso group; a C.sub.1-4 alkyl group optionally substituted with a carboxyl group, an amino group, or a hydroxy group; or CONH.sub.2; with the proviso that R.sub.2 and R.sub.5 may form a ring; when X.sub.2 is a single bond, R.sub.3 is not a hydrogen atom, or R.sub.1 to R.sub.3 are not a methyl group; and when X.sub.2 is NR.sub.5 and three of R.sub.1 to R.sub.3 and R.sub.5 are a hydrogen atom, the other one is not a hydrogen atom or a methyl group; and a pH is 5.0 or less. According to the present invention, a polishing composition capable of polishing not only polycrystalline silicon but also a silicon nitride film at high speed and also suppressing a polishing speed of a silicon oxide film is provided.

A polishing composition comprising an abrasive grain; a modified microfibril cellulose in which at least a part of the cellulose units has a hydroxyl group at the C6 position oxidized to a carboxyl group; and a dispersion medium, wherein each content of Na and K is 100 ppm or less relative to the solids weight.

A polishing composition comprising an abrasive grain; a modified microfibril cellulose in which at least a part of the cellulose units has a hydroxyl group at the C6 position oxidized to a carboxyl group; and a dispersion medium, wherein each content of Na and K is 100 ppm or less relative to the solids weight.

The present invention provides, in polishing an object to be polished that contains an (a) material having silicon-nitrogen bonding and (b) other materials, means that is capable of improving a ratio of a polishing speed of the (a) material to a polishing speed of the (b) materials.

The present invention relates to a polishing composition used for polishing an object to be polished that contains an (a) material having silicon-nitrogen bonding and (b) other materials, the polishing composition containing: organic acid-immobilized silica; a dispersing medium; a selection ratio improver that improves a ratio of a polishing speed of the (a) material to a polishing speed of the (b) materials; and an acid, in which the selection ratio improver is organopolysiloxane having a hydrophilic group.

The present invention provides a method for producing a polishing composition which can polish an object to be polished at a high polishing speed and with fewer scratches (defects). The present invention is a method for producing a polishing composition, the method including: preparing silica in which an intensity of a peak of a silica four-membered ring structure and an intensity of a peak derived from a silica random network structure when analyzed by Raman spectroscopy satisfy a predetermined requirement; and mixing the silica with a dispersing medium.

The present invention provides a method for producing a polishing composition which can polish an object to be polished at a high polishing speed and with fewer scratches (defects). The present invention is a method for producing a polishing composition, the method including: preparing silica in which an intensity of a peak of a silica four-membered ring structure and an intensity of a peak derived from a silica random network structure when analyzed by Raman spectroscopy satisfy a predetermined requirement; and mixing the silica with a dispersing medium.

A polishing composition that can not only achieve high polishing speed, but also can improve the surface smoothness (surface quality) of a polished substrate and reduce defects is provided. That is, provided is a polishing composition comprising silica particles and a water soluble polymer, wherein the contained silica particles satisfy the following requirements (a) to (c): (a) the primary particle diameter based on the specific surface area is 5 to 300 nm; (b) the coefficient of variation in the particle diameter is 10% or less; and (c) the Sears number Y is 10.0 to 12.0.

A polishing method for polishing by sliding a semiconductor silicon wafer, held by a polishing head, against a polishing pad attached to a turn table while supplying a polishing agent, wherein the semiconductor silicon wafer is subjected to primary polishing, secondary polishing, and final polishing in turn, the secondary polishing comprises polishing by an alkaline based polishing agent which includes free abrasive grains and does not include a water-soluble polymer agent, and subsequent rinse polishing by a polishing agent which includes a water-soluble polymer agent and the rinse polishing includes two stages of polishing, wherein, after performing a first stage of the rinse polishing while supplying a polishing agent which includes a water-soluble polymer agent, a second stage of the rinse polishing is performed while supplying a switched polishing agent whose water-soluble polymer agent has an average molecular weight larger than the polishing agent of the first stage.

A method of producing a wafer includes forming a peel-off layer in a hexagonal single-crystal ingot by applying a laser beam having a wavelength transmittable through the ingot while positioning a focal point of the laser beam in the ingot at a depth corresponding to the thickness of a wafer to be produced from an end face of the ingot, generating ultrasonic waves from an ultrasonic wave generating unit positioned in facing relation to the wafer to be produced across a water layer interposed therebetween, thereby to break the peel-off layer, and detecting when the wafer to be produced is peeled off the ingot based on a change that is detected in the height of an upper surface of the wafer to be produced by a height detecting unit positioned above the upper surface of the wafer to be produced across the water wafer interposed therebetween.