Investigation of Plasma Enhanced Chemical Vapor Deposition Chamber Mismatching by Photoluminescence and Raman Spectroscopy

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Photoluminescence (PL) spectra from lightly boron (B) doped p − -Si(100) under 488.0 nm Ar + ion laser excitation over the temperature range of 22 K-290 K is presented. Change of PL peak height (maximum intensity), peak position, peak area (areal intensity), full-width-at-half-maximum (FWHM: peak width) were determined as a function of temperature. PL intensity was sharply decreased with temperature increase in the temperature range of 22 K -170 K and then slowly increased again in the temperature range of 170 K-290 K. Phonon replicas of a relatively sharp band-to-band (or band edge (BE)) PL peak were clearly measured at low temperatures (≤90 K). PL spectra became broader and the phonon replicas were barely distinguishable as the temperature was increased. The envelope of the main PL peak and the broadening of peak width with the Si temperature were qualitatively in good agreement with the Maxell-Boltzmann probability distribution function. The direction of peak position shift with Si temperature change was also in good agreement with the temperature dependence of the Si bandgap. All measured PL spectra were curve fitted using combinations of modified Gaussian function(s) and standard Gaussian function(s). A simplified curve fitting method for broad PL spectra, consisting of the BE peak and band tail peak, using an exponentially modified Gaussian (EMG or ExGaussian) function and a number of standard Gaussian functions, was proposed from a practical usage point of view. Radiative recombination processes in Si and potential industrial applications of the PL characterization technique were discussed. For the characterization of electrical behaviors of Si, resistivity, carrier concentration, mobility and Hall effect measurements were routinely inspected during wafer fabrication and incoming quality control at the wafer fabs.1 A number of noncontact characterization techniques, such as microwave detected photoconductance decay (μ-PCD)1,2 and inductively coupled quasi-steady-state photoconductance (QSSPC), 1,3 have been used for in-line monitoring of contamination and process induced modulation of electrical behaviors of Si. Steady state PCD measurement techniques 4 enabled by improved laser technology were recently introduced.With the introduction of photoluminescence (PL) imaging and spectrum analysis, a noncontact, purely optical technique is now available for spatially resolved electrical characterization. For industrial applications, the ease of measurement without special sample preparation is important. This is especially true for in-line monitoring applications in semiconductor device manufacturers. PL measurements at room temperature (RT) are preferred. However, the RTPL spectra from Si are generally very broad and it is difficult to identify the origin of variations in RTPL spectra. In this paper, temperature dependence of PL spectra from lightly boron (B) doped p − -Si(100) was measured in the temperature range of 22 K-290 K and the effect of temperature on the change of PL spectra was investigated. Practic...

Section: Resultsmentioning

confidence: 99%

“…Few examples of RTPL applications in Si device processes can be found in previous reports. 7,[10][11][12][13][14][15][16][28][29][30][31]34…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Temperature Dependence of Photoluminescence Spectra from Crystalline Silicon

Yoo¹,

Kang²,

Murai

et al. 2015

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“…15,16 The RTPL technique has been used for characterizing metal contamination, various process induced damage of Si (i.e, plasma process induced damage (PPID), implantation induced damage, residual damage after implant activation annealing), surface passivation, dielectric/Si interface quality etc. [17][18][19][20][21][22][23][24] The same technique can be applied to in-line monitoring of bonding interface quality through the correlation between electrical properties and PL spectra (including intensity) of bonded Si wafers.In this study, ordinary and bonded, 200 mm Si wafers with different surface finishing conditions were characterized by RTPL. RTPL is examined as a potential in-line characterization technique for bonded Si wafers for BSI CIS applications.…”

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confidence: 99%

Photoluminescence Characterization of Interface Quality of Bonded Silicon Wafers

Yoo¹,

Ishigaki²,

Kang³

2015

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Wafer-to-wafer bonding is implemented in fabrication of backside illuminated (BSI) complimentary metal-oxide-semiconductor image sensor (CIS) devices in volume manufacturing. A wafer with illuminated imager and a wafer with readout and image processing electronics are fabricated separately and assembled using wafer-to-wafer bonding. Since the illuminated imager and a wafer with readout and image processing electronics are facing each other at the bonded interface, the quality of wafer-to-wafer bonding interface can affect the performance of finished devices. Room temperature photoluminescence (RTPL) technique was studied as a non-contact, in-line characterization technique for assessing bonding interface quality. Ordinary and bonded, 200 mm Si wafers, with different surface finishing conditions, were characterized by RTPL under two different excitation wavelengths (650 nm and 827 nm) to investigate the effects of surface finishing conditions. Significant variations in RTPL spectra and intensity, suggesting potential electrical property variations, were observed from bonded wafers. RTPL characterization results on ordinary and bonded wafers are introduced as a potential technique for in-line bonding interface quality monitoring. Wafer bonding has become a very powerful technology and has been widely used for micro-electro-mechanical systems (MEMS) and micro-optical-electro-mechanical systems (MOEMS) over the last decade.1-5 Backside illuminated (BSI) complimentary metal-oxidesemiconductor image sensor (CIS) devices became a very important wafer bonding-based application to overcome the pixel area limitation by metal interconnects in conventional CIS devices. 6,7 The backside has to be fully available for capturing light after the wafer processing to maximize image signal by maximum utilization of chip area.For successful BSI CIS device fabrication, void-free wafer bonding, uniform Si wafer thinning without severe damage, backside wafer treatment, metal interconnect and color filter formation within CMOS device fabrication compatible temperature are required. 8,9 Since the device performance is influenced by subtle residual process-induced variations such as contaminants, stress and bonding interface quality, advanced characterization techniques for early in-line detection of potential problems are strongly desired.To achieve high and stable production yields, a very robust and highly reliable wafer bonding technique must be established before going any further. Defects in bonded wafers have been major obstacles for BSI CIS mass production for years.9 Three types of bonded wafer imaging techniques using infrared (IR) transmission, ultrasonic and X-ray topography have been developed for bonding quality characterization to look for the source of bonding problems.10 Particles, local deformation of Si and surface roughness are found to be the major sources of void formation at the bonding interface.11 Three basic steps of Si wafer bonding (i.e. surface preparation, contacting and annealing) 2 have been significantly ...

“…15 Plasma process induced damage (PPID) and plasma process chamber mismatch monitoring were also demonstrated using RTPL characterization of Si wafers. [16][17][18] In this paper, RTPL was investigated as a potential noncontact electrical activation monitoring technique for implant annealed Si wafers. The major objectives were to understand the correlation between the degree of implant activation after RTA (determined by sheet resistance measurement and SIMS) and RTPL spectra/intensity for practical usage of the RTPL technique for noncontact electrical activation monitoring.…”

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confidence: 99%

Noncontact Monitoring of Activation and Residual Damage of Dual Implanted Silicon Using Room Temperature Photoluminescence

Yoo¹,

Jeon

Kim

et al. 2015

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Phosphorous (P + 1.0 MeV, 4.0 × 10 13 cm −2 ) and boron (B + 10 keV, 3.0 × 10 14 cm −2 ) implanted p − -Si(100) wafers were annealed with a wide range of annealing conditions (350-800 • C, 60-150 s) in a commercially available hot wall-based, rapid thermal annealing (RTA) system. Significant variations in sheet resistance were observed in different RTA conditions. Secondary ion mass spectroscopy (SIMS) P and B depth profiles did not show significant change. Room temperature photoluminescence (RTPL) spectra were measured from all wafers under two different excitation wavelengths (650 and 785 nm). RTPL spectra showed large variations in intensity and wavelength distribution corresponding to the sheet resistance. © The Author Conventional methods of noncontact monitoring for as-implanted Si are Therma-Probe and Rutherford backscattering spectroscopy (RBS). Secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM) are also used for dose, depth profile, and implant damage characterization. After electrical activation by thermal treatment of implanted Si, sheet resistance (Rs) measurements using four point probes are mainly used for monitoring implanted dopant activation. However, the four point probes require physical contact and relatively large area (typically one or more orders of magnitude wider than the probe spacing) of uniform quality (poor spatial resolution) for meaningful measurements. SIMS, RBS and TEM are also used as complementary crystal quality and defect verification techniques after implanted dopant activation.1-4 However, the conventional characterization techniques often overlook problems due to their insensitivity to surface passivation quality, residual implant damage and defects. 5Development of a noncontact, high spatial resolution implant activation monitoring technique is desired. Photoluminescence (PL) from Si is a good candidate for this application.Room temperature photoluminescence (RTPL) of crystalline Si, at wavelength ∼1.1 μm corresponding to interband transitions, is very sensitive to the density of non-radiative bulk and surface defects. 1,6 This can be used as an indication of defect concentration in Si. Monitoring of surface defect formation during oxidation processes and minor carrier diffusion length of epitaxial Si by RTPL intensity has been reported previously. 7,8 Promising results of spectroscopic RTPL studies on (ultra-) shallow implanted junctions and high energy low dose implanted junctions have also been reported previously.2,5,9-11 RTPL characterization of non-radiative defect density on surfaces and interfaces of Si with thin oxides have been studied.12-14 Metal contamination monitoring using spectroscopic RTPL has been reported previously.15 Plasma process induced damage (PPID) and plasma process chamber mismatch monitoring were also demonstrated using RTPL characterization of Si wafers. [16][17][18] In this paper, RTPL was investigated as a potential noncontact electrical activation monitoring technique for implant annealed Si wafers. The major...