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AssigneeHoya Corporation
InventorsKesahiro Koike, Junji Miyagaki
Estimating the term…
In a method of producing a glass substrate for a mask blank, a surface of the glass substrate is polished by the use of an alkaline polishing liquid that contains colloidal silica abrasive grains, from which alkali metal is removed to suppress occurrence of an alkali metal gel substance protrusion adhered on the glass substrate. The polishing process may include a surface roughness control step for initially finishing the surface of the glass substrate to a predetermined surface roughness by moving a polishing member and the glass substrate relative to each other under a predetermined pressure. This may be followed by a protrusion suppressing step under a pressure lower than the predetermined pressure, to minimize polishing rate and suppress occurrence of a fine convex protrusion.
A method of producing a glass substrate for a mask blank, in which a surface of the glass substrate is polished by the use of a polishing liquid containing abrasive grains, wherein:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Polishing compositions: containing abrasives or grinding agents
Operating processes therefor: characterised by the composition of the lapping agent
Polishing compositions
Machines, devices, or processes for grinding or polishing
Term ended 19 Aug 2023 (estimated)
This application claims priority to prior Japanese patent application JP 2002-238576, the disclosure of which is incorporated herein by reference.
This invention relates to a glass substrate for a mask blank without fine convex surface defects on the surface of the substrate, a method of producing the same, a mask blank using the glass substrate, a method of producing the same, a transfer mask, a method of producing the same, and a method of producing a semiconductor device.
Following the recent development of a higher-density and higher-accuracy VLSI device, a glass substrate for an electronic device, such as a glass substrate for a mask blank, is required to have good flatness and less surface defects. Such demand becomes more and more strict year by year.
A sole FIGURE shows a double-sided polishing apparatus used in this invention.
Now, description will be made in detail about a method of producing a glass substrate for a mask blank, a method of producing a mask blank, a method of producing a transfer mask, and a method of producing a semiconductor device. Thereafter, description will be made in detail about a glass substrate for a mask blank, a mask blank, and a transfer mask.
In the following description, fine convex surface defects (hereinafter may simply be called “protrusion defects”) represent convex protrusions containing Si and O as main components and having a height on the order of several nanometers and another dimension ranging from several tens of nanometers to 2000 nanometers.
In a method of producing a glass substrate for a mask blank according to a first embodiment, when the surface of the glass substrate is polished by the use of a polishing liquid containing abrasive grains, colloidal silica abrasive grains produced by hydrolysis of an organosilicon compound is used as the abrasive grains.