Abstract: The wafer having a retardation distribution measured with a light having a wavelength of 520 nm, wherein an average value of the retardation is 38 nm or less, wherein the wafer comprises a micropipe, and wherein a density of the micropipe is 1.5/cm2 or less, is disclosed.

Abstract: In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens of higher quality by controlling the water content in the diamine hydrochloride composition for preparing a diisocyanate within a specific range.

Abstract: Provided is a polishing pad including a polishing layer, wherein the nuclear magnetic resonance (NMR) 13C spectrum of a processed composition prepared by adding 1 g of the polishing layer to a 0.3 M aqueous solution of potassium hydroxide (KOH) and allowing the mixture to react in a closed container at a temperature of 150° C. for 48 hours includes a first peak appearing at 15 ppm to 18 ppm, a second peak appearing at 9 ppm to 11 ppm, and a third peak appearing at 138 ppm to 143 ppm, and the area ratio of the third peak to the second peak is about 5:1 to about 10:1. The polishing pad may exhibit physical properties corresponding to the above-described peak characteristics, thereby achieving a removal rate and defect prevention performance within desired ranges in polishing of a polishing target.

Abstract: The wafer having a retardation distribution measured with a light having a wavelength of 520 nm, wherein an average value of the retardation is 38 nm or less, wherein the wafer comprises a micropipe, and wherein a density of the micropipe is 1.5/cm2 or less, is disclosed.

Abstract: The method of preparing a silicon carbide ingot includes: disposing a raw material and a silicon carbide seed crystal to be separated in a reactor having an internal space; adjusting a temperature, a pressure, and an atmosphere of the internal space for sublimating the raw material and growing the silicon carbide ingot on the silicon carbide seed crystal; and cooling the reactor and retrieving the silicon carbide ingot, wherein the adjusting proceeds in a first inert gas atmosphere having a flow quantity of 100 sccm to 300 sccm, the cooling proceeds in a second inert gas atmosphere having a flow quantity of 1 sccm to 250 sccm, and the reactor has a thermal conductivity of 120 W/mK or less.

Abstract: The wafer having a retardation distribution measured with a light having a wavelength of 520 nm, wherein an average value of the retardation is 38 nm or less, wherein the wafer comprises a micropipe, and wherein a density of the micropipe is 1.5/cm2 or less, is disclosed.

Abstract: The present invention provides a graphite sheet having a ratio of thermal diffusivity in horizontal and vertical directions of 300 or more. Also, the present invention provides a graphite sheet having a ratio of thermal diffusivity in a vertical direction of 2.0 mm2/s or less. The graphite sheet has excellent thermal conductivity in horizontal and vertical directions and excellent flexibility at the same time and can be produced at low manufacturing cost, thereby holding an economic advantage.

Abstract: In the embodiments, an aqueous hydrochloric acid solution and an organic solvent instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens, which are excellent in yield and quality with mitigated environmental problems by controlling the total content of metals, cations, or anions in a diamine hydrochloride composition.

Abstract: In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens of high quality in which the content of water, the content of cations, or the content of an aromatic compound containing 3 or more of chlorine (Cl) in the organic solvent used in the reaction of a diamine hydrochloride composition and triphosgene is adjusted to a specific range.

Abstract: The diisocyanate composition according to an embodiment of the present invention comprises, in the composition, a benzyl isocyanate having a methyl group in an amount of 5 ppm to 200 ppm, an aromatic compound having a halogen group in an amount of 5 ppm to 1,000 ppm, a benzyl isocyanate having an ethyl group in an amount of 1 ppm to 1,000 ppm, or a combination thereof. It is possible to improve the optical characteristics by preventing the occurrence of yellowing, striae, and cloudiness and to enhance the mechanical properties such as impact resistance at the same time. Thus, it can be advantageously used to prepare an optical material of high quality.

Abstract: In the embodiments, an aqueous hydrochloric acid solution instead of hydrogen chloride gas and solid triphosgene instead of phosgene gas may be used in the process of preparing a diisocyanate from a diamine through a diamine hydrochloride. In addition, the embodiments provide processes for preparing a diisocyanate composition and an optical lens of higher quality by controlling the water content in the diamine hydrochloride composition for preparing a diisocyanate within a specific range.

Abstract: The diamine composition according to an embodiment of the present invention comprises a benzylmonoamine having a methyl group in an amount of 10 ppm to 2,000 ppm in the composition. When it is used for the preparation of a diisocyanate composition and an optical material, it is possible to improve the optical characteristics by preventing the occurrence of yellowing, striae, and cloudiness in the optical material and enhancing the mechanical properties such as impact resistance at the same time. In addition, in the process for preparing a diisocyanate composition according to another embodiment, the b* value according to the CIE color coordinate of a diamine composition is adjusted to a specific range, whereby it is possible to enhance not only the yield and purity of the diisocyanate composition but also the optical characteristics of the final optical lens. Thus, the process for preparing a diisocyanate composition can be applied to the preparation of a plastic optical lens of high quality.

Abstract: The embodiments provide a polishing pad, a process for preparing the same, and a process for preparing a semiconductor device using the same. In the polishing pad according to an embodiment, the average value of the modulus of the pore region and that of the non-pore region is adjusted to 0.5 GPa to 1.6 GPa, whereby it is possible to achieve an excellent life span, to improve the scratches and surface defects appearing on the surface of a semiconductor substrate, and to further enhance the polishing rate.

Abstract: A method for preparing a SiC ingot includes preparing a crucible assembly comprising a crucible body having an internal space, loading a raw material into the internal space of the crucible body and placing a plurality of SiC seed in the internal space of the crucible body at regular intervals spaced apart from the raw material, and growing the SiC ingot from the plurality of SiC seed by adjusting the internal space of the crucible body to a crystal growth atmosphere such that the raw material is vapor-transported and deposited to the plurality of SiC seed. A density of the crucible body may be 1.70 to 1.92 g/cm3.

Abstract: A method for preparing a SiC ingot includes: preparing a reactor by disposing a raw material in a crucible body and disposing a SiC seed in a crucible cover, and then wrapping the crucible body with a heat insulating material having a density of 0.14 to 0.28 g/cc; and growing the SiC ingot from the SiC seed by placing the reactor in a reaction chamber and adjusting an inside of the reactor to a crystal growth atmosphere such that the raw material is vapor-transported and deposited to the SiC seed.

Abstract: A SiC ingot includes: a main body including a first cross-sectional plane of the main body and a second cross-sectional plane of the main body facing the first cross-sectional plane; and a protrusion disposed on the second cross-sectional plane and including a convex surface from the second cross-sectional plane of the main body, wherein a first end point disposed at one end of the second cross sectional plane, a second end point disposed at another end of the second cross sectional plane, and a peak point disposed on the convex surface are disposed on a third cross-sectional plane of the main body perpendicular to the first cross-sectional plane, and wherein a radius of curvature of an arc corresponding to a line of intersection between the third cross-sectional plane and the convex surface satisfies Equation 1 below: 3D?r?37D??[Equation 1] where r is the radius of curvature of the arc corresponding to the line of intersection between the third cross-sectional plane and the convex surface, and D is a leng

Abstract: A method for preparing a SiC ingot includes loading a composition of a raw material comprising a carbon source and a silicon source into a reactor; placing a plurality of seed crystal on one side of the reactor spaced apart from the composition; and sublimating the composition such that the SiC ingot grows from the plurality of seed crystal. A flow factor of the composition may be 5 to 35.

Abstract: A graphite sheet having a ratio of thermal diffusivity in horizontal and vertical directions of 300 or more is disclosed. Also, a graphite sheet having a ratio of thermal diffusivity in a vertical direction of 2.0 mm2/s or less is disclosed. The graphite sheet has excellent thermal conductivity in horizontal and vertical directions and excellent flexibility at the same time and can be produced at low manufacturing cost, thereby holding an economic advantage.

Abstract: The embodiments relate to a porous polyurethane polishing pad and a process for preparing a semiconductor device by using the same. The porous polyurethane polishing pad comprises a urethane-based prepolymer and a curing agent, and has a thickness of 1.5 to 2.5 mm, a number of pores whose average diameter is 10 to 60 ?m, a specific gravity of 0.7 to 0.9 g/cm3, a surface hardness at 25° C. of 45 to 65 Shore D, a tensile strength of 15 to 25 N/mm2, an elongation of 80 to 250%, an AFM (atomic force microscope) elastic modulus of 101 to 250 MPa measured from a polishing surface in direct contact with an object to be polished to a predetermined depth wherein the predetermined depth is 1 to 10 ?m.

Abstract: The embodiments relate to a porous polyurethane polishing pad and a process for preparing a semiconductor device by using the same. The porous polyurethane polishing pad comprises a urethane-based prepolymer and a curing agent, and has a thickness of 1.5 to 2.5 mm, a number of pores whose average diameter is 10 to 60 ?m, a specific gravity of 0.7 to 0.9 g/cm3, a surface hardness at 25° C. of 45 to 65 Shore D, a tensile strength of 15 to 25 N/mm2, an elongation of 80 to 250%, an AFM (atomic force microscope) elastic modulus of 30 to 100 MPa measured from a polishing surface in direct contact with an object to be polished to a predetermined depth wherein the predetermined depth is 1 to 10 ?m.