US Patent 8003919 Substrate heat treatment apparatus

A heat-treating plate has support elements projecting from an upper surface thereof. The support elements are located at apexes of equilateral triangles arranged regularly and continually. The heat-treating plate and a substrate placed on the support elements form a minute space therebetween which is sealed by a sealer. The substrate is sucked by reducing the pressure in the minute space to a negative pressure through exhaust bores. Since all the distances between adjoining support elements are equal, the substrate sags in the same amount between these support elements. With such arrangement of the support elements, sagging of the substrate is inhibited efficiently by a reduced number of support elements.