Etching process state judgment method and system therefor

An etching process state judgment method comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step, in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process by detecting a change in emission magnitude along with a wavelength, to obtain peak characteristics;
• a common peak identifying step, in which peaks common to the wafers are identified among the peaks detected in the peak detection step, and
• a state detection step, in which the peak characteristics are compared regarding the common peaks, to detect a state of each wafer in the etching process, wherein:
• the etching process state judgment method comprises:
• a peak elimination step, in which the peaks detected in the peak detection step are eliminated from the optical emission spectrum distribution, to obtain a peak-eliminated optical emission spectrum distribution;
• a global distribution characteristics calculation step, in which a plurality of magnitudes at respective prescribed wavelength positions are obtained from the peak-eliminated optical emission spectrum distribution, to obtain global distribution characteristics indicating global variation of the optical emission spectrum distribution;
• and
• a correction step, in which with respect to a global distribution characteristic of a wafer that becomes a baseline, a ratio of a global distribution characteristic of another wafer is obtained at each wavelength position, and the original optical emission spectrum distribution of the another wafer is multiplied by the ratio at each wavelength position to obtain a corrected optical emission spectrum distribution from which difference between wafers has been eliminated;
• and
• in the state detection step, peak characteristics of peaks in the corrected optical emission spectrum distribution obtained in the correction step are compared between wafers, to detect difference between states of the wafers in the etching process.

An etching process state judgment method comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step, in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process by detecting a change in emission magnitude along with a wavelength, to obtain peak characteristics;
• a common peak identifying step, in which peaks common to the wafers are identified among the peaks detected in the peak detection step;
• and
• a state detection step, in which the peak characteristics are compared regarding the common peaks, to detect a state of each wafer in the etching process, the method further comprising:
• a step, in which optical emission spectrum distributions are obtained for a plurality of wafers, and data indicating a surface shape or an etching rate of each of a wafer for which the optical emission spectrum distribution has been monitored are obtained;
• a model formula calculation step, in which a model formula showing a relation between the surface shape or etching rate of the wafer and the peak characteristics of the optical emission spectrum distribution of the wafer is obtained by multiple regression analysis;
• a step, in which an optical emission spectrum distribution is obtained by monitoring optical emission of a wafer as an object of prediction;
• a step, in which peak characteristics is obtained from the optical emission spectrum distribution of the wafer as the object of prediction;
• and
• a step, in which the peak characteristics of the optical emission spectrum distribution of the wafer as the object of prediction are used to estimate a surface shape or an etching rate of the wafer as the object of prediction by using the model formula.

An etching process state judgment method comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step, in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process by detecting a change in emission magnitude along with a wavelength, to obtain peak characteristics;
• a common peak identifying step, in which peaks common to the wafers are identified among the peaks detected in the peak detection step;
• and
• a state detection step, in which the peak characteristics are compared regarding the common peaks, to detect a state of each wafer in the etching process, the method further comprising:
• a step, in which optical emission spectrum distributions are obtained for a plurality of wafers, and data indicating a surface shape or an etching rate of each of a wafer for which the optical emission spectrum distribution has been monitored are obtained;
• a model formula calculation step, in which a model formula showing a relation between the surface shape or etching rate of the wafer and the peak characteristics of the optical emission spectrum distribution of the wafer is obtained by multiple regression analysis;
• a step, in which an optical emission spectrum distribution is obtained by monitoring optical emission of a wafer as an object of prediction;
• a step, in which peak characteristics is obtained from the optical emission spectrum distribution of the wafer as the object of prediction;
• and
• a step, in which the peak characteristics of the optical emission spectrum distribution of the wafer as the object of prediction are used to estimate a surface shape or an etching rate of the wafer as the object of prediction by using the model formula, wherein:
• in the model formula calculation step, a number of peak characteristics that are introduced into the model formula among the peak characteristics detected in the peak detection step is reduced.

An etching process state judgment method comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process by detecting a change in emission magnitude along with a wavelength, to obtain peak characteristics;
• a common peak identifying step, in which peaks common to the wafers are identified among the peaks detected in the peak detection step;
• and
• a state detection step, in which the peak characteristics are compared regarding the common peaks, to detect a state of each wafer in the etching process, further comprising:
• a step of obtaining an optical emission spectrum distribution at regular intervals between a start of the etching process and an end point of a prescribed early process;
• a step of arranging on time scale the peak characteristics detected in the peak detection step;
• a step of normalizing the peak characteristics by using a maximum value and a minimum value on a time scale for each peak characteristic;
• a step of obtaining a stability index, in which a difference between a peak characteristic at each point and the peak characteristic at the end point of the early process is divided by a standard deviation of the peak characteristic on a time scale, and then a quotient is squared, and the stability index is obtained as an average of the resultant peak characteristics at each point;
• and
• a stabilization judgment step, in which the early process of etching is judged to be stabilized when an average of the stability index among the wafers becomes less than a prescribed value or a chi-square value at which a degree of freedom becomes a peak number.

An etching process state judgment method comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step, in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process by detecting a change in emission magnitude along with a wavelength, to obtain peak characteristics;
• a common peak identifying step, in which peaks common to the wafers are identified among the peaks detected in the peak detection step;
• and
• a state detection step, in which the peak characteristics are compared regarding the common peaks, to detect a state of each wafer in the etching process, further comprising:
• a step of obtaining an optical emission spectrum distribution at regular intervals between a start of the etching process and an end point of a prescribed early process;
• a step of arranging on time scale the peak characteristics detected in the peak detection step;
• a step of normalizing the peak characteristics by using a maximum value and a minimum value on a time scale for each peak characteristic;
• a step of detecting a state of the etching process, in which:
• a square of a difference between a normalized characteristic of a wafer that becomes a criterion and a normalized characteristic of another wafer at a same wavelength position is obtained while shifting a time of the normalized characteristic of the another wafer,
• the square of the difference of the peak characteristic is time-averaged in a range in which the criterion normalized peak characteristic and a time-shifted normalized peak characteristic of the another wafer overlap in time;
• a time shift value for which a time-average of the square of the difference becomes smallest is taken as a lag or advance, and a lag value is obtained as that time shift value;
• and
• a state of the etching process is detected on a basis of a magnitude of the lag value.

An etching process state judgment method, comprising:

• a spectral data obtaining step, in which an optical emission spectrum distribution is obtained by monitoring optical emission during an etching process of a plurality of wafers;
• a peak detection step, in which peaks are detected from the optical emission spectrum distribution at a specific time point during the etching process, to obtain peak characteristics;
• and
• a state detection step in which:
• an optical emission spectrum distribution of a previously-determined criterion wafer is taken as baseline, and a spectral ratio of an optical emission spectrum distribution of another wafer with respect to the baseline is obtained at each wavelength position;
• a standard deviation of the spectral ratio is obtained at each of wavelength positions arranged at intervals of a prescribed width;
• a derivative of the spectral ratio is obtained at each of the wavelength positions arranged at intervals of the prescribed width;
• a dispersion index is obtained by dividing the standard deviation by an absolute value of the derivative at each of the wavelength positions arranged at intervals of the prescribed width;
• and
• a change of a state of the another wafer with respect to the criterion wafer is detected on a basis of the dispersion index.