Optical measurement apparatus and optical measurement method

An optical measurement apparatus, comprising:

• a probe including a transmissive optical member having a reference surface, the probe being configured to irradiate a sample with light through the reference surface, and to receive a first reflected light from the reference surface, a second reflected light from a front side of the sample, and a third reflected light from a back side of the sample;
• and
• a calculator, which is configured to calculate a first distance from the reference surface to the front side of the sample with use of a first reflection interference light to be generated by the first reflected light and the second reflected light, and to calculate a thickness of the sample with use of a second reflection interference light to be generated by the second reflected light and the third reflected light,
• the optical measurement apparatus being configured to:
• irradiate, under a state in which the sample is not placed on a stage, by the probe, the stage with the light through the reference surface to receive the first reflected light, and a fourth reflected light from a surface of the stage;
• calculate, by the calculator, a second distance from the reference surface to the stage with use of a third reflection interference light to be generated by the first reflected light and the fourth reflected light;
• and
• calculate, by the calculator, a third distance between the back side of the sample and the stage with the second distance being an additive element, and with the first distance and the thickness of the sample being subtractive elements.

An optical measurement method, which is performed with use of a probe including a transmissive optical member having a reference surface, and a spectrometer, the optical measurement method comprising:

• irradiating a sample with light through the reference surface with use of the probe;
• receiving, by the probe, a first reflected light from the reference surface, a second reflected light from a front side of the sample, and a third reflected light from a back side of the sample;
• measuring, with use of the spectrometer, a spectrum of measurement reflected light including a first reflection interference light to be generated by the first reflected light and the second reflected light, and a second reflection interference light to be generated by the second reflected light and the third reflected light;
• and
• calculating a first distance from the reference surface to the front side of the sample with use of the first reflection interference light, and calculating a thickness of the sample with use of the second reflection interference light,
• the transmissive optical member having an optical thickness that is larger than an upper limit value of a coherent optical thickness, which is defined by an upper limit value of a measurement wavelength range of the spectrometer and by a wavelength resolution of the spectrometer.

An optical measurement method, which is performed with use of a probe including a transmissive optical member having a reference surface, the optical measurement method comprising:

• irradiating a sample with light through the reference surface with use of the probe;
• receiving, by the probe, a first reflected light from the reference surface, a second reflected light from a front side of the sample, and a third reflected light from a back side of the sample;
• calculating a first distance from the reference surface to the sample with use of a first reflection interference light to be generated by the first reflected light and the second reflected light, and calculating a thickness of the sample with use of a second reflection interference light to be generated by the second reflected light and the third reflected light;
• irradiating, under a state in which the sample is not placed on a stage, the stage with the light through the reference surface with use of the probe to receive, by the probe, the first reflected light, and a fourth reflected light from a surface of the stage;
• calculating a second distance from the reference surface to the stage with use of a third reflection interference light to be generated by the first reflected light and the fourth reflected light;
• and
• calculating a third distance between the back side of the sample and the stage with the second distance being an additive element, and with the first distance and the thickness of the sample being subtractive elements.