Pattern measuring method and pattern measuring apparatus
A pattern measuring method and a pattern measuring apparatus that efficiently prevent a measurement error inherent to a device that performs beam scanning in a specific direction such as a scanning electron microscope are provided. The invention is directed to a pattern measuring method and a pattern measuring apparatus in which a first curve with respect to an edge of one side and a second curve with respect to an edge of the other side are obtained by calculating a first power spectral density with respect to the edge of one side of a pattern and a second power spectral density with respect to the edge of the other side of the pattern based upon a signal that is obtained when a charged particle beam is scanned in a direction intersecting the edge of the pattern; a difference value between the first curve and the second curve is calculated; and one of the first curve and the second curve is corrected by using the difference value.
1. A pattern measuring method of generating a signal waveform based upon a detection signal that is obtained by two-dimensionally scanning a charged particle beam with respect to a pattern formed on a sample, and measuring the pattern by using the signal waveform, wherein
a first curve indicating a first power spectral density with respect to an edge of one side of the pattern and a second curve indicating a second power spectral density with respect to an edge of the other side of the pattern are obtained by calculating the first power spectral density with respect to the edge of the one side of the pattern and the second power spectral density with respect to the edge of the other side of the pattern based upon a signal that is obtained when the charged particle beam is scanned in a direction intersecting the edge of the pattern;
a difference value between the first curve and the second curve is calculated; and
one of the first curve and the second curve is corrected by using the difference value.
2. The pattern measuring method according to claim 1 , wherein
the charged particle beam is scanned in such a manner that the charged particle beam is irradiated on the edge of the one side earlier than the edge of the other side on a scanning line of the charged particle beam.
3. The pattern measuring method according to claim 1 , wherein
a spectral intensity corresponding to a predetermined frequency is obtained from the first curve or the second curve; and
the spectral intensity corresponding to the predetermined frequency is subtracted from the first curve or the second curve.
4. The pattern measuring method according to claim 1 , wherein
it is determined whether or not an inclination depending on a change in a frequency of the difference value between the first curve and the second curve is zero or equal to or less than a predetermined value.
5. A pattern measuring apparatus for measuring a pattern formed on a sample by using a signal that is obtained from a scanning region by scanning a beam on the sample, comprising:
an arithmetic processing device in which the signal is acquired; a first curve indicating a first power spectral density with respect to an edge of one side of the pattern and a second curve indicating a second power spectral density with respect to an edge of the other side of the pattern are obtained by calculating the first power spectral density with respect to the edge of the one side of the pattern and the second power spectral density with respect to the edge of the other side of the pattern based upon a signal that is obtained by scanning the beam in a direction intersecting the edge of the pattern; a difference value between the first curve and the second curve is calculated; and one of the first curve and the second curve is corrected by using the difference value.
6. The pattern measuring apparatus according to claim 5 , wherein
the arithmetic processing device obtains the second power spectral density based upon a signal obtained from an edge on which a charged particle beam is irradiated earlier on a scanning line of the charged particle beam; and
obtains the first power spectral density based upon a signal obtained from an edge on which the charged particle beam is irradiated later on the scanning line of the charged particle beam, in one pattern.
7. The pattern measuring apparatus according to claim 5 , wherein
the arithmetic processing device obtains a spectral intensity corresponding to a predetermined frequency from the first curve or the second curve; and
the spectral intensity corresponding to the predetermined frequency is subtracted from the first curve or the second curve.
8. The pattern measuring apparatus according to claim 5 , wherein
the arithmetic processing device determines whether or not an inclination depending on a change in a frequency of the difference value between the first curve and the second curve is zero or equal to or less than a predetermined value.