Optical heating device with angled light holding substrate and method of heating treatment thereof

An optical heating device that heats a substrate to be treated by irradiating light, the optical heating device comprising:

• a support member supporting the substrate to be treated;
• and
• a light source unit including a plurality of LED substrates each having a first main surface on which a plurality of LED elements are mounted, wherein
• at least one of the plurality of LED substrates is arranged such that the first main surface is inclined to a second main surface of the substrate to be treated when the substrate to be treated is supported by the support member,
• each of the plurality of LED substrates are arranged so that an angle between the first main surface and the second main surface of the substrate to be treated is between 20° and 60° when the substrate to be treated is supported by the support member, and
• each of the plurality of LED substrates are arranged to satisfy formulae (1) to (3) below, wherein a distance between a center of the LED substrate at the first main surface and the substrate to be treated at the first main surface when the substrate to be treated is supported by the support member is Wd;
• a distance from a center of the substrate to be treated to the center of the LED substrate at the first main surface when viewed from a direction orthogonal to the second main surface of the substrate to be treated is Rd;
• an angle between the first main surface of the LED substrate and the second main surface of the substrate to be treated is θ,
• 60 mm≤Wd≤200 mm (1)
• 0.75≤Rd/Wd≤2.5 (2)
• arctan(Rd/(2·Wd))≤0≤arctan(Rd/Wd) (3).