Spectroscopic reflectometer

A spectroscopic reflectometer characterized by comprising a head, a photo-detector, an internal reflection mechanism and a reflectance calculation unit:

• wherein
• (1) the head is adapted to project measurement light to an object and introduce reflection light from the object irradiated by the measurement light;
• wherein
• (2) the photo-detector is adapted to detect an intensity of the received light, having its light receiving part placed in a position at which the reflection light introduced into the head arrives;
• wherein
• (3) the internal reflection mechanism has a variable light reflectance in binary and is placed in a position at which a part of the measurement light arrives and the reflection light reflected by the internal reflection mechanism reaches the light receiving part of the photo-detector within the head;
• and wherein
• (4) in a subordinate period in which variation in the output value of the photo-detector is substantially negligible, the reflectance calculation unit measures first to third output values to be described later by performing any one of following operations a and b, and
• also, in a main measurement period in which variation in the output value of the photo-detector is negligible, other than the subordinate measurement period, the reflectance calculation unit measures fourth to sixth output values to be described later by performing any one of following operations c and d, whereby the light reflectance of the inspection work is calculated based on the first to sixth output values:
• wherein
• (a.) the reflectance calculation unit measures the first and second output values that are output values of the photo-detector respectively when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is varied in binary, and measures the third output value that is an output value of the photo-detector when a calibration sample of a known light reflectance is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values;
• wherein
• (b.) the reflectance calculation unit measures the first output value that is an output value of the photo-detector when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values, and measures the second and third output values that are output values of the photo-detector respectively when a calibration sample of a known light reflectance is used as the object and the light reflectance of the internal reflection mechanism is varied in binary;
• wherein
• (c.) the reflectance calculation unit measures the fourth and fifth output values that are output values of the photo-detector respectively when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is varied in binary, and measures the sixth output value that is an output value of the photo-detector when an inspection work to be measured is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values;
• and wherein
• (d.) the reflectance calculation unit measures the fourth output value that is an output value of the photo-detector when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values, and measures the fifth and sixth output values that are output values of the photo-detector respectively when the inspection work to be measured is used as the object and the light reflectance of the internal reflection mechanism is varied in binary.

A method of measuring a reflectance, provided with a head adapted to project a measurement light to an object and introduce a reflection light from the object irradiated by the measurement light;

• a photo-detector placed in a position at which the reflection light introduced into the head arrives;
• and an internal reflection mechanism having a variable light reflectance in binary and placed in a position at which a part of the measurement light arrives and the reflection light reflected by the internal reflection mechanism reaches the light receiving part within the head,
• in a subordinate measurement period in which variation in the output value of the photo-detector is substantially negligible, measuring a first output value that is an output value of the photo-detector in a state of substantially no light being introduced, a second output value that is an output value of the photo-detector when a dark sample which substantially reflects no light is used as the object, and a third output value that is an output value of the photo-detector when a calibration sample of a known light reflectance is used as the object;
• in a main measurement period in which variation in the output value of the photo-detector is substantially negligible, other than the subordinate measurement period, measuring a fourth output value that is an output value of the photo-detector in a state of substantially no light being introduced, a fifth output value that is an output value of the photo-detector when the dark sample is used as the object, and a sixth output value that is an output value of the photo-detector when an inspection work to be measured is used as the object;
• and
• calculating the light reflectance of the inspection work based on the first to sixth output values.

A method of measuring a reflectance, provided with a head adapted to project a measurement light to an object and introduce reflection light from the object irradiated by the measurement light;

• a photo-detector placed in a position at which the reflection light introduced into the head arrives;
• and an internal reflection mechanism having a variable light reflectance in binary and placed in a position at which a part of the measurement light arrives and the reflection light reflected by the internal reflection mechanism reaches the light receiving part within the head,
• in a subordinate period in which variation in the output value of the photo-detector is substantially negligible, measuring first to third output values to be described later by performing any one of following operations a and b;
• in a main measurement period in which variation in the output value of the photo-detector is negligible, other than the subordinate measurement period, measuring fourth to sixth output values to be described later by performing any one of following operations c and d;
• and
• calculating the light reflectance of the inspection work based on the first to sixth output values:
• (a.) measuring the first and second output values that are output values of the photo-detector respectively when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is varied in binary, and measuring the third output value that is an output value of the photo-detector when a calibration sample of a known light reflectance is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values;
• (b.) measuring the first output value that is an output value of the photo-detector when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values, and measuring the second and third output values that are output values of the photo-detector respectively when a calibration sample of a known light reflectance is used as the object and the light reflectance of the internal reflection mechanism is varied in binary;
• (c.) measuring the fourth and fifth output values that are output values of the photo-detector respectively when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is varied in binary, and measuring the sixth output value that is an output value of the photo-detector when an inspection work to be measured is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values;
• and
• (d.) measuring the fourth output value that is an output value of the photo-detector when a dark sample which substantially reflects no light is used as the object and the light reflectance of the internal reflection mechanism is set to any one of the binary values, and measuring the fifth and sixth output values that are output values of the photo-detector respectively when the inspection work to be measured is used as the object and the light reflectance of the internal reflection mechanism is varied in binary.