Stress Generation in PECVD Silicon Nitride Thin Films for Microelectronics Applications

Abstract

Thin SiN films deposited by plasma enhanced chemical vapor deposition (PECVD) have been analyzed by a variety of analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), X-ray reflectivity (XRR), and Rutherford Backscattering Spectrometry/Hydrogen Forward Scattering (RBS/HFS) to collect data on bonding, density and chemical composition respectively. Both tensile and compressive SiN films have been deposited and analyzed. Mechanisms of stress formation in SiN thin films are discussed. It has been found that amount of bonded hydrogen as detected by FTIR is higher for compressive films compared to tensile SiN films. Amount of bonded hydrogen in a film is correlated well with tensile stress. Effect of deposition temperature and other process parameters on stress have been studied. Exposure of SiN films to elevated temperature after deposition lead to increase in tension and degradation in compressive stress. New approaches to stress generation in thin films like creation of multilayer film structures have been delineated.

Non-contact, non-destructive characterization of Ge content and SiGe layer thickness using multi-wavelength Raman spectroscopy

“…Microscopic Raman scattering is a powerful, nondestructive technique for characterizing crystallinity and the degree of stress/strain of the crystal [3][4][5][6][7][8][9][10][11][12][13]. For this purpose intensity, shift, and full-width-at-half-maximum (FWHM) of Raman signals are measured.…”

“…Accurate measurement of strain and/or Ge content is extremely important for process optimization and manufacturing devices with high performance uniformity, repeatability and reliability. Raman spectroscopy has been proposed by many research groups as a promising characterization technique [1,[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…The enhanced electron and hole mobility of strained Si and strained Si 1-x Ge x /Si makes them very attractive as candidate materials for high performance semiconductor devices, such as high speed CMOS and HBT devices [1][2][3][4][5][6]. The thickness of a Si 1-x Ge x layer, its Ge content and crystallinity of the Si 1-x Ge x /Si determine the amount of strain and the enhancement of the carrier transport properties.…”

“…In addition to the lack of availability of automatic handling of large size wafers, measurement accuracy, repeatability, spectral resolution, spatial resolution and calibration related issues have been preventing practical application of this technique from achieving wide acceptance as an in-line monitoring technique in the industry. Since the introduction of strain and Ge in Si for device performance enhancement, Raman spectroscopy has been revisited by many researchers as a preferred, non-destructive stress/strain characterization technique for semiconductor materials for the last few years [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Non-Contact and Non-Destructive Measurement of Ge and B Content in Si1-xGex/Si Using Very High Resolution Multiwavelength Raman Spectroscopy

“…Si 1-x Ge x layers, with wide ranges of Ge and B concentrations, are introduced into the device fabrication process. The basic parameters of a Si 1-x Ge x layer determine the amount of strain and the degree of carrier transport property enhancement [1][2][3][4]. However, in-line monitoring of the basic parameters, such as Ge content, B content, stress/strain and Si 1-x Ge x layer thickness, is technically challenging because it requires non-contact and non-destructive characterization.…”