Ion implant monitoring through measurement of modulated optical response
AssigneeTherma-Wave, Inc.
InventorsAlex Salnik, Lena Nicolaides, Jon Opsal
Life of this patent
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Abstract
A method for simultaneously monitoring ion implantation dose, damage and/or dopant depth profiles in ion-implanted semiconductors includes a calibration step where the photo-modulated reflectance of a known damage profile is identified in I-Q space. In a following measurement step, the photo-modulated reflectance of a subject is empirically measured to obtain in-phase and quadrature values. The in-phase and quadrature values are then compared, in I-Q space, to the known damage profile to characterize the damage profile of the subject.
Claims16
A method of optically inspecting and evaluating ion implantation in a subject, the method comprising:
- identifying calibration points within an I-Q space that correspond to the photo-modulated reflectance of known ion concentrations;
- making multiple photo-modulated reflectance measurements of the subject to obtain in-phase and quadrature values;
- and
- comparing the in-phase and quadrature values obtained from the subject to the calibration points to compare the ion concentrations of the subject to the known ion concentrations.
A method of evaluating ion concentration in a sample comprising the steps of:
- periodically exciting at least one region on the sample;
- directing a probe beam to reflect off each region on the sample surface that has been periodically excited;
- monitoring the reflected probe beam at each region and generating an output signal in response thereto;
- analyzing the output signal with a phase synchronous detection system and generating in-phase and quadrature signals;
- and
- evaluating the ion concentration of each region by comparing values of the in-phase versus the quadrature signals to predetermined reference values.
A device for evaluating ion concentration in a sample, the device comprising:
- a first illumination source producing an intensity modulated beam for periodically exciting at least one region on the sample;
- a second illumination source producing a probe beam to reflect off each region on the sample surface that has been periodically excited;
- a detector for monitoring the reflected probe beam at each region and generating an output signal in response thereto;
- a lock-in amplifier for analyzing the output signal to generate in-phase and quadrature signals;
- and
- a processor for evaluating ion concentration at each region by comparing values of the in-phase versus the quadrature signals to predetermined reference values.
A method of evaluating variations in dopant concentration in a semiconductor sample, the method comprising:
- directing an intensity modulated pump beam and a probe beam to the sample surface;
- obtaining measurements by analyzing the reflected probe beam, each measurement composed of an in-phase (I) value and a quadrature (Q) value;
- and
- analyzing variations in dopant concentration for the semiconductor sample as a function of the I and Q values included in the measurements.
Dependencies are inferred from the claim text.