Multi pump-probe encoding-decoding for opto-acoustic metrology

A metrology device for opto-acoustic metrology of a sample, comprising:

• a pump arm that is configured to receive at least a first portion of pulsed light from a light source and to direct a pump beam comprising pump pulses towards a surface of the sample, wherein the pump beam generates vertical transient perturbations in the sample and lateral transient perturbations in the sample;
• a probe arm that is configured to receive at least a second portion of the pulsed light from the light source and to direct a plurality of probe beams towards different locations on the surface of the sample, each probe beam comprising probe pulses, the probe arm comprising a means for modulating each probe beam in the plurality of probe beams, the plurality of probe beams is reflected from the surface of the sample, wherein a first reflected probe beam is modified based on the vertical transient perturbations propagating perpendicular to the surface of the sample and at least one second reflected probe beam is modified based on the lateral transient perturbations in the sample propagating along the surface of the sample;
• means for demodulating the first reflected probe beam and the at least one second reflected probe beam;
• and
• means for determining at least one characteristic of the sample based on the vertical transient perturbations obtained from demodulating the first reflected probe beam and based on the lateral transient perturbations obtained from demodulating the at least one second reflected probe beam.

A method of opto-acoustic metrology of a sample, comprising:

• generating a plurality of pump beams, each pump beam comprising pump pulses;
• modulating each pump beam in the plurality of pump beams;
• directing the plurality of pump beams towards different locations on a surface of the sample, wherein each pump beam excites transient perturbations in the sample at corresponding locations;
• directing a probe beam comprising probe pulses towards the surface of the sample, the probe beam is reflected from the surface of the sample, wherein a reflected probe beam is modified based on vertical transient perturbations in the sample propagating perpendicular to the surface of the sample and lateral transient perturbations propagating along the surface of the sample that are excited by the plurality of pump beams;
• demodulating the reflected probe beam;
• and
• determining at least one characteristic of the sample based on the vertical transient perturbations and the lateral transient perturbations obtained from demodulating the reflected probe beam.

A metrology device for opto-acoustic metrology of a sample, comprising:

• a pump arm that is configured to receive at least a first portion of pulsed light from a light source and to direct a plurality of pump beams towards different locations on a surface of the sample, each pump beam comprising pump pulses, the pump arm comprising a means for modulating each pump beam in the plurality of pump beams, wherein each pump beam excites transient perturbations in the sample at corresponding locations;
• a probe arm that is configured to receive at least a second portion of the pulsed light from the light source and to direct a probe beam comprising probe pulses towards the surface of the sample, the probe beam is reflected from the surface of the sample, wherein a reflected probe beam is modified based on vertical transient perturbations in the sample propagating perpendicular to the surface of the sample and lateral transient perturbations propagating along the surface of the sample that are excited by the plurality of pump beams;
• means for demodulating the reflected probe beam;
• and
• means for determining at least one characteristic of the sample based on the vertical transient perturbations and the lateral transient perturbations obtained from demodulating the reflected probe beam.