Rapid photoreflectance spectroscopy for strained silicon metrology

Abstract

We present an improved photoreflectance (PR) spectroscopy technique upon the prior art in providing a rapid acquisition method of the PR spectrum in a simultaneous and multiplexed manner. Rapid PR (RPR) application is the on-line monitoring of strained silicon. Shrinkage in the silicon bandgap is measured and converted to strain, using theoretical models. Experimental RPR results are in good correlation with Raman spectroscopy.

Fast Differential Reflectance Spectroscopy of Semiconductor Structures for Infrared Applications by Using Fourier Transform Spectrometer

“…In order to solve it, the use of a multichannel silicon-based charge-coupled device (CCD) camera detection system instead of a single-channel lock-in amplifier system in the case of near-infrared and UV spectral ranges in typical grating-based experimental configuration has been proposed. 15,16) Unfortunately, this cannot be extended to wavelengths longer than about 2.2 m due to the lack of suitable multichannel detector. The experimental conditions become even more complex in the mid and far infrared due to a very rich spectrum of absorption lines connected with atmospheric gases which strongly affect the measured total spectra of reflectivity or transmission.…”

Micro-photoreflectance spectroscopy for microscale monitoring of plasma-induced physical damage on Si substrate

“…5,6) For this reason, it has become crucial to accurately measure PPD as the wafers are being processed (in situ) in the production line. [12][13][14] Since the first attempts in 1997, 15,16) a number of reports have focused on the usage of PRS to characterize the surfaces of semiconductor wafers bombarded with ions, [17][18][19][20] but PRS has not yet achieved wide use. 7) Photoreflectance spectroscopy (PRS) is one of such optical techniques, which has been used to understand the fundamental characteristics of semiconductor materials, [8][9][10] and to measure gate oxide charging damage 11) as well as strain/stress on the wafer.…”

“…7) Photoreflectance spectroscopy (PRS) is one of such optical techniques, which has been used to understand the fundamental characteristics of semiconductor materials, [8][9][10] and to measure gate oxide charging damage 11) as well as strain/stress on the wafer. [12][13][14] Since the first attempts in 1997, 15,16) a number of reports have focused on the usage of PRS to characterize the surfaces of semiconductor wafers bombarded with ions, [17][18][19][20] but PRS has not yet achieved wide use. One of the factors that have limited its applicability is the fact that, in traditional PRS setups, the spot sizes are on the order of 1 mm 2 , up to 1 cm 2 in some techniques.…”

Note: A signal-to-noise ratio enhancement based on wafer light irradiation system for optical modulation spectroscopy measurement

“…Recent reports have suggested the use of the photoreflectance (PR) spectroscopy, a form of the optical modulation spectroscopy, as an online tool for the strain silicon metrology. 1,2 In PR experiments on silicon samples, the optical properties can be altered by the absorption of an intensity modulated energy source called pump beam. As a result, the sample dielectric function undergoes periodic variations at the modulation frequency of the pump excitation.…”

“…Optical modulation spectroscopy can be applied to characterize a strained silicon layer or a silicon-germanium layer with the conversion of the E1 transition energies to strain or to the Ge alloy mole fraction. 1 A potential application of the optical modulation technique is the measurement and the control of the uniaxial strain in silicon which can be deliberately induced by means of crystallographic epitaxial growth and the manipulation of crystal lattice constant parameters. The strain is more commonly induced by the formation of local deposits of silicon germanium alloy on either side of the silicon transistor channel, resulting in the compression of the silicon such as to induce uniaxial strain.…”