Etching end-point detecting method

A method for end point detection of etching where, when an object to be processed is etched using plasma, emission spectra of plasma are sequentially measured by light detecting means, an end point of etching is detected on the basis of change of the emission spectra, comprising:

• the step of etching a sample (the same kind as the following object to be processed) of the object prior to etching the object to sequentially measure full-spectra of plasma during the etching;
• and
• the step of obtaining weighting factors for each wavelength, the weighting factors weighting all wavelengths of each full-spectrum accumulated until an etching end of the sample according to respective emission intensities, and further comprising;
• the step of adding the emission intensities of all the wavelengths for each of the full-spectra sequentially measured during etching of the object in addition with the respective weighting factors;
• and
• the step for an end point detection of etching of detecting an end point of etching on the basis of the degree of change of an additional value of the emission intensities for each of full-spectra sequentially measured.