Patent TW-I383469-B (TW)
Title: A method of revealing crystalline defects in a bulk substrate
Inventor: REYNAUD PATRICK
IPC: H01L21/70
Filed: 2007-02-09
Granted: 2013-01-21
Abstract: The process for predictively revealing crystal defects exist in a latent state in a bulk silicon substrate, comprises a revealing heat treatment of bulk substrates conducted in a non-reducing atmosphere at 950[deg]C for 6 hours. The substrates become apparent only after subsequent processing. The step of revealing heat treatment is carried out inside an enclosure for 3 minutes in which a gas mixture comprising 10 ppm of oxygen with respect to a total volume of gas mixture present in the enclosure and argon and/or nitrogen. The process for predictively revealing crystal defects exist in a latent state in a bulk silicon substrate, comprises a revealing heat treatment of bulk substrates conducted in a non-reducing atmosphere at 950[deg]C for 6 hours. The substrates become apparent only after subsequent processing. The step of revealing heat treatment is carried out inside an enclosure for 3 minutes in which a gas mixture comprising 10 ppm of oxygen with respect to a total volume of gas mixture present in the enclosure and argon and/or nitrogen. The step of revealing heat treatment is carried out before a dry oxidation stage, followed by a deoxidation stage of the bulk substrate to completely eliminate the formed oxide layer in which the deoxidation is carried out by a treatment with hydrofluric acid. The step of revealing heat treatment comprises a dry and/or wet thermal oxidation of the substrate carried out in an atmosphere containing oxygen, optionally argon and/or nitrogen in which oxidation is followed by the deoxidation stage to completely eliminate the formed oxide layer. The wet oxidation of the bulk substrate is carried out at 500-1300[deg]C for 3 minutes to 10 hours to form a silicon oxide layer of a thickness of 500-900 nm. The dry oxidation of the bulk substrate is carried out at 950[deg]C for 5 minutes to form a silicon oxide layer of a thickness of about 10 nm. After the step of revealing of crystal defect and the stage of deoxidation, carrying out an additional stage of enlargement of the defects revealed by the heat treatment of revelation. The stage of enlargement of the crystalline defects comprises a rapid heat treatment at 100-1300[deg]C for few seconds to few minutes. The rapid heat treatment is rapid thermal annealing, which is carried out in presence of argon and/or hydrogen, and is rapid thermal oxidation, which is carried out in presence of oxygen. The rapid thermal annealing for enlarging crystalline defects can be performed in a batch annealing furnace, which is carried out under an atmosphere of neutral gas and/or hydrogen at 1100-1250[deg]C for few minutes to few hours. After the stage of crystalline defect enlargements, a silicon deposition step deposits a silicon layer of few micrometers thick on the bulk substrate by epitaxial growth to enhance the revealing of crystal defects. Independent claims are included for: (1) a process of measuring a density of crystalline defects; (2) a bulk silicon substrate; and (3) a process of manufacturing a bulk silicon substrate.