Defect inspection apparatus and defect inspection method

A defect inspection method comprising:

• a step of irradiating a sample including a silicon carbide substrate, a buffer layer formed on the silicon carbide substrate, and a drift layer formed on the buffer layer with excitation light;
• a step of transmitting photoluminescence light generated from the sample through a filter unit that controls a wavelength band to be transmitted;
• a step of detecting the photoluminescence light transmitted through the filter unit;
• a step of forming an image from the detected photoluminescence light;
• and
• a step of discriminating a defect captured in the formed image, wherein
• in the step of transmitting the photoluminescence light,
• the filter unit transmits the wavelength band including 420 nm or longer and 430 nm or shorter in the photoluminescence light, and
• in the step of discriminating the defect,
• when a thickness of the drift layer is defined as D1, a thickness of the buffer layer is defined as D2, an offset angle is defined as θ, and a first length and a second length are defined as L1 and L2 indicated respectively as follows:
• L
• ⁢
• 1
• =
• (
• D
• ⁢
• 1
• +
• D
• ⁢
• 2
• )
• /
• tan
• ⁢
• θ
• L
• ⁢
• 2
• =
• D
• ⁢
• 2
• /
• tan
• ⁢
• θ
• ,
• the defect is discriminated as the defect including a basal plane dislocation continuing from the buffer layer to the drift layer in a case where a length of the defect belongs to a predetermined first range including the first length, and
• the defect is discriminated as the defect including the basal plane dislocation in the buffer layer and an edge dislocation in the drift layer in the case where the length of the defect belongs to a predetermined second range including the second length, the second range being different from the first range.