Method and apparatus for measuring the concentration of ions implanted in semiconductor materials

A method for determining a concentration of ions implanted in a silicon or polysilicon sample, comprising the steps of:

• generating at least two excitation laser sub-pulses;
• irradiating a region of the material with a grating pattern, formed by overlapping the at least two excitation laser sub-pulses, to initiate a time-dependent, decaying non-oscillatory response in the region;
• diffracting a probe laser pulse, having a duration that is at least long as the time-dependent response, off the region to generate a time-dependent signal beam;
• detecting the time-dependent signal beam to generate a signal waveform;
• and
• processing the signal waveform to determine the concentration of ions implanted in the silicon or polysilicon sample.

An apparatus for determining a concentration of ions implanted in a semiconducting material, comprising:

• an excitation laser for generating an excitation laser pulse;
• a beam-delivery system comprising a phase mask for separating the excitation laser pulse into at least two sub-pulses and then irradiating a region of the material with a grating pattern formed by overlapping the at least two sub-pulses to initiate a time-dependent response in the region;
• a probe laser for generating a probe laser pulse having a duration that is at least as long as the time-dependent response and an orientation such that the probe pulse diffracts off the region to generate a time-dependent signal beam;
• a photodetector for detecting the time-dependent signal beam to generate a signal waveform;
• and
• a processor for processing the signal waveform to determine the concentration of ions implanted in the material.

A method for determining a concentration of ions implanted in a material comprising:

• passing an excitation pulse through a phase mask to generate at least two excitation laser sub-pulses,
• irradiating a region of the material with a grating pattern, formed by overlapping two excitation laser sub-pulses, to initiate a time-dependent response in the region,
• diffracting a probe laser pulse, having a duration that is at least long as the time-dependent response, off the region to generate a time-dependent signal beam,
• detecting the time-dependent signal beam to generate a signal waveform,
• processing the signal waveform to determine its amplitude at a point in time, and
• comparing the amplitude of the signal waveform to a database that correlates amplitudes of previously measured signal waveforms to concentrations of ions implanted in materials to determine the concentration of ions implanted in the material.