K-space Associates, Inc.

Darryl Barlett

Charles A Taylor, Ii

Roy Clarke

Douglas Perry

Barry Dean Wissman

Jason Williams

Greg DeMaggio

Scott Hines

The invention is an optical method and apparatus for measuring the temperature of semiconductor substrates in real-time, during thin film growth and wafer processing. Utilizing the nearly linear dependence of the interband optical absorption edge on temperature, the present method and apparatus result in highly accurate measurement of the absorption edge in diffuse reflectance and transmission geometry, in real time, with sufficient accuracy and sensitivity to enable closed loop temperature control of wafers during film growth and processing. The apparatus operates across a wide range of temperatures covering all of the required range for common semiconductor substrates.

Apparatus and method for real time measurement of substrate temperatures for use in semiconductor growth and wafer processing

A method and apparatus for determining the synchronicity of a rotary platen () in a vacuum deposition chamber (). A light source () projects a highly collimated light beam () onto the rotating platen (), thereby tracing a circular swept path (). The swept path () passes alternately through samples () on the platen () and intervening webs (). The samples () are significantly more reflective than the webs (). The platen () includes an asymmetry feature () along the swept path (). A detector () measures light signals reflected from the platen () along the swept path (), and generates a unique signal upon encountering the asymmetry feature (). A microcontroller generates a trigger pulse synchronized to the unique signal.

Non-contact, optical sensor for synchronizing to free rotating sample platens with asymmetry

A technique for determining the temperature of a sample including a semiconductor filmhaving a measurable optical absorption edge deposited on a transparent substrateof material having no measurable optical absorption edge, such as a GaN filmdeposited on an Al2O3 substratefor blue and white LEDs. The temperature is determined in realtime as the filmgrows and increases in thickness. A spectra based on the diffusely scattered light from the filmis produced at each incremental thickness. A reference division is performed on each spectra to correct for equipment artifacts. The thickness of the filmand an optical absorption edge wavelength value are determined from the spectra. The temperature of the filmis determined as a function of the optical absorption edge wavelength and the thickness of the filmusing the spectra, a thickness calibration table, and a temperature calibration table.

Thin film temperature measurement using optical absorption edge wavelength

A temperature monitoring technique for collecting radiation intensity (blackbody emission) across a broad wavelength range. A solid state spectrometer () acquires spectra from a sample () in real time and resolves the spectra to a radiation intensity (I) versus wavelength (&#x3bb;) curve. This curve is fitted to Planck's equation using a non-linear least squares fitting analysis. The system can be configured to self-calibrate and then lock in an amplitude value (A) which is used in subsequent temperature measurements by fitting to the blackbody emission curve. Preferably, the spectrometer () is flat field corrected () in an initial step to counteract variations in the spectrometer response with wavelength.

Blackbody fitting for temperature determination

Apparatus for quantitatively measuring the curvature and/or relative tilt of large surfaces wherein a small array of parallel laser beams, each separated by a known distance, reflect from the surface of a sample and fall upon a feedback controlled front-surface steering mirror to a detector that measures both the change in separation of the reflected beams and the spatial translation of the entire array on the detector. The sample surface is translated beneath or in front of the fixed laser array by means of a computer controlled stage or other apparatus to create a 1-dimensional line scan or 2-dimensional map of both bow and relative tilt of the sample surface. A computer-driven, feedback-controlled steering mirror compensates for varying sample tilt by precisely realigning the reflected laser array onto the detector as the sample is translated. The apparatus also utilizes a laser with intensity feedback control to continuously optimize the reflected laser power for varying surface reflectivity as the sample is translated. This combination provides a means to quantitatively measure curvature and relative tilt of sample areas much larger than the actual laser beam array size.

Growing community of inventors

Dexter, MI, United States of America

Darryl Barlett