Method and system for monitoring a process of material removal from the surface of a patterned structure

An optical system for use in controlling a process of material removal from the surface of a patterned structure, to determine at least one of residue, erosion, dishing and corrosion effects in the structure, the system comprising:

• an imaging system having an illuminator unit, a detector unit, and a light directing arrangement for directing incident light to the structure and directing light reflected from the structure to the detector unit, the light directing arrangement comprising a phase modulator accommodated in optical path of the reflected light propagating to the detector, an output of the detector being in the form of at least one intensity map;
• and
• a control unit connectable to the imaging system and operable to receive the output of the detector and process it to obtain data indicative of a phase map of the structure, the control unit having a data processing and analyzing utility operating to analyze the phase map to determine at least one of the following:
• the value of at least one of the erosion and dishing effects in a selected site of the structure, determined by a phase difference between the selected site and a reference site of the structure spaced-apart from said selected site, wherein said reference site has a relatively small value of the measured effect as compared to that of the selected site;
• a difference ΔDD of the dishing effects between a selected site of the structure and a relatively small reference site of the structure spaced-apart from the selected site;
• an absolute value of the dishing effect in the selected site which is relatively large as compared to a reference site of the structure spaced-apart from the selected site, by utilizing correlation between the difference ΔDD and an absolute value of the dishing effect;
• a difference ΔED between the dishing and erosion effects in a selected site of the structure and a reference site of the structure spaced-apart from the selected site;
• absolute values of the dishing and erosion effects in the selected and reference sites, by utilizing correlation between the difference ΔED and absolute value of the dishing and erosion effects;
• a difference of the erosion effects between a selected patterned site of the structure and a relatively small reference patterned site of the structure;
• a difference ΔEE between the erosion effects in a selected site of the structure and a reference site spaced-apart from the selected site;
• an absolute value of the erosion effect in said selected site utilizing correlation between the difference ΔEE and an absolute value of the erosion effect;
• presence of defects or, corrosion effect in the structure;
• presence of residue effect in the structure.

An optical system for use in controlling a process of material removal from the surface of a patterned structure, to determine at least one of residue, erosion, dishing and corrosion effects in the structure, the system comprising:

• an imaging system having an illuminator unit, a detector unit, and a light directing arrangement for directing incident light to the structure and directing light reflected from the structure to the detector unit, the light directing arrangement comprising a phase modulator accommodated in optical path of the reflected light propagating to the detector, an output of the detector being in the form of at least one intensity map;
• a spectrophotometer system operable for applying spectrophotometric measurements to at least one reference site of the structure spaced-apart from a selected site of the structure and thereby obtaining output in the form of intensities of light reflected from the at least one reference site of the structure as a function of wavelength of incident light;
• and
• a control unit connectable to the imaging system and to the spectrophotometer system, and operable to receive the output of these systems and process them to obtain data indicative of a phase map of the structure and data indicative of the reflective properties of a layer stack of the structure in the at least one reference site, the control unit having a data processing and analyzing utility operating to determine at least one of the following:
• an absolute value of the dishing effect in the selected site;
• an absolute value of the erosion effect in the selected site having the pattern characterized by at least one of a small pitch and a large metal duty cycle (DC) value;
• a difference ΔDD of the dishing effects between the selected site and the relatively small reference site;
• an absolute value of the dishing effect in the selected site, by utilizing correlation between the difference ΔDD and an absolute value of the dishing effect;
• a difference ΔED between the dishing and erosion effects in the selected and reference sites;
• an absolute value of one of the dishing and erosion effects utilizing correlation between the difference ΔED and an absolute value of one of the dishing and erosion effects;
• a difference ΔEE between the erosion effects in the selected and reference sites of the structure;
• absolute values of the erosion effect in the selected site utilizing correlation between the difference ΔEE and an absolute value of the erosion effect;
• presence of defects or corrosion effect in the structure;
• presence of residue effect in the structure.