PURPOSE: To prepare a suitable quartz tool suitably used in the high-temperature treatment of semiconductor apparatuses, by assembling the tool from a sintered crystalline quartz material having a transparent quartz layer on the surface layer thereof, and forming transparent quartz layers on parts to be cut.

CONSTITUTION: Crystalline quartz particles of high purity are packed in a cylindrical heating apparatus of desired inside diameter, and the particles are sintered under reduced pressure to form crystalline quartz rods 3 constituted of a sintered crystalline quartz layer 1 having the transparent quartz layer 2 on the surface thereof. The crystalline quartz rods 3 of a given length are welded through a transparent quartz 4 by an oxyhydrogen flame, etc. to prepare the top and the bottom frames 5 and 6. The top and the bottom frames 5 and 6 are then joined with columns 7 consisting of the crystalline quartz rods 3 and then legs 8. Grooves 9 for supporting a substrate are cut and formed on the top and the bottom frames 5 and 6 by using a diamond wheel, and the exposed rough surfaces of the sintered crystalline quartz layers 1 are molten by an oxyhydrogen flame, etc. to form transparent quartz layers 10 on the surfaces of the grooves 9 and give the aimed quartz tool.