<i>In</i> <i>situ</i> laser reflectance interferometry measurement of diamond film growth

Zuiker, C.; Gruen, D. M.; Krauss, A. R.

doi:10.1063/1.361406

Cited by 33 publications

(30 citation statements)

References 16 publications

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“…11 A similar formulation has been used to study diamond film growth. 12 This formula is written in the form for an ambient/rough film/substrate system, but can be easily generalized to a system of multilayer smooth films with a rough top film by replacing r 12 with the complex reflection coefficient for the smooth layer film stack. For normal incidence applications, the cosine terms are both 1, and the Fresnel coefficients are polarization independent; for off-normal incidence applications (such as ellipsometry), the Fresnel coefficients for s or p polarization are evaluated as usual.…”

Section: Methodsmentioning

confidence: 99%

High-speed, high-accuracy optical measurements of polycrystalline silicon for process control

Benson¹,

Ramamoorthy²,

Kamlet³

et al. 1998

Thin Solid Films

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Highly accurate non-contact polycrystalline silicon (poly-Si) film thickness measurements are important for both real-time feedback control and run-to-run control. Both spectroscopic ellipsometry (SE) and normal-incidence spectral reflectometry (SR) are complicated by poly-Si surface effects and variable bulk poly-Si refractive indices. In this paper we will describe an empirical modification of Beckmann/Kirchhoff scattering theory to account for the effects of rough layers in SR. We will present results from in situ monitoring of reactive ion etching of polySi/SiO 2 /Si, and ex situ comparisons to TEM and AFM. Preliminary conclusions on the applications of this model to SE analysis of poly-Si will also be presented. IntroductionHighly accurate non-contact polycrystalline silicon (poly-Si) film thickness measurements are important for both real-time feedback control and run-to-run control. Both spectroscopic ellipsometry (SE) and normal-incidence spectral reflectometry (SR) are complicated by poly-Si surface roughness effects 1,2,3,4 and variable bulk poly-Si refractive indices. 5,6 The accuracy of poly-Si thickness measurements is usually more strongly limited by the models employed than raw measurement noise or instrument calibration errors. These model-related systematic errors directly limit the minimum time required for extraction of in situ etch rates because the thickness change over this minimum time must be larger than the systematic and random errors. 7 We will present a 2 simple scalar scattering theory method for modeling the poly-Si surface roughness effects and will present results using this model in high-speed poly-Si reactive ion etch (RIE) rate monitoring. We will present quantitative comparisons between in situ SR data and ex situ TEM and AFM measurements that show significant improvements in the accuracy of both bulk film and surface roughness thicknesses obtained using this model vs. the commonly employed Bruggemann effective media approximation (BEMA) model for surface roughness. Improvements in the dynamic response of the etch rate monitor will be shown. We will also discuss the use of the B/K model for SE measurements of poly-Si and improvements in the models for the bulk poly-Si dielectric function. Experimental DetailsWe use a low-cost Ocean-Optics™ CCD spectrometer/W-halogen lamp system to perform high-speed, in situ normal incidence SR measurements over the 400-800nm wavelength range on poly-Si/SiO 2 /Si samples during reactive ion etching . The details of this system, accuracy comparisons to a commercially available spectrophotometer, thickness accuracy tests vs. SE on SiO 2 /Si samples, and its initial applications to high-speed in situ monitoring of poly-Si RIE have been previously presented. 7,8 SR data with 5nm resolution can be collected in 40 ms with good raw signal-to-noise ratios. Ex situ spectroscopic ellipsometry data was collected using a Sopra GESP-5 variable-angle rotating polarizer ellipsometer run in the tracking analyzer mode.Analysis of both SR and SE data wa...

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Section: Methodsmentioning

confidence: 99%

High-speed, high-accuracy optical measurements of polycrystalline silicon for process control

Benson¹,

Ramamoorthy²,

Kamlet³

et al. 1998

Thin Solid Films

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“…The substrate temperature was maintained at 800 'C, and the microwave power level was 500 watts. Laser interferometry [31] was used to determine when diamond film growth begins, with an estimated reproducibility of 300-400~. Once the initial growth has begun, the gas composition and pressure are altered to grow the films using the desired processes corresponding to equations 1, 2, or 3.…”

Section: Methodsmentioning

confidence: 99%

Morphology and Electron Emission Properties of Nanocrystalline CVD Diamond Thin Films

et al. 1997

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Nanocrystalline diamond thin films have been produced by microwave plasma-enhanced chemical vapor deposition (MPECVD) using C60/Ar/H2 or CH4/Ar/H2 plasmas. Films grown with H2 concentration ≤ 20% are nanocrystalline, with atomically abrupt grain boundaries and without observable graphitic or amorphous carbon phases. The growth and morphology of these films are controlled via a high nucleation rate resulting from low hydrogen concentration in the plasma. Initial growth is in the form of diamond, which is the thermodynamic equilibrium phase for grains < 5 nm in diameter. Once formed, the diamond phase persists for grains up to at least 15–20 nm in diameter. The renucleation rate in the near-absence of atomic hydrogen is very high (∼1010 cm2sec−1), limiting the average grain size to a nearly constant value as the film thickness increases, although the average grain size increases as hydrogen is added to the plasma. For hydrogen concentrations less than ∼20%, the growth species is believed to be the carbon dimer, C2, rather than the CH3* growth species associated with diamond film growth at higher hydrogen concentrations. For very thin films grown from the C60 precursor, the threshold field (2 to ∼60 volts/micron) for cold cathode electron emission depends on the electrical conductivity and on the surface topography, which in turn depends on the hydrogen concentration in the plasma. A model of electron emission, based on quantum well effects at the grain boundaries is presented. This model predicts promotion of the electrons at the grain boundary to the conduction band of diamond for a grain boundary width ∼3–4 Å, a value within the range observed by TEM.

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“…It allows determining the film growth rate and deposition of films with a specified thickness. Among numerous thickness measurement methods, the most often used ones are (I) stylus profilometry [4], (II) scanning electron microscopy (SEM) [5] and (III) optical methods (ellipsometry, time-and spectral-domain interferometry) [6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…Film thickness is being determined based on parameters of light transmitted or reflected from the film surface: (I) polarisation (ellipsometry) [8], (II) intensity (time-domain interferometry) [10][11][12][13] or (III) spectrum (spectral-domain interferometry) [9,13]. Optical techniques are based on the assumed film optical model therefore the model parameters inaccuracy can cause errors in the thickness measurement.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, they enable in situ film monitoring which is critical in diagnostics or studying of CVD process kinetics [6,14]. In optical systems, the angle of incidence of light onto the film may be fixed [10][11][12] or scanned within a specified range [15][16][17]. The second approach allows an analysis of additional features of the film, such as surface quality [15] or mechanical stress [16], however they are difficult to apply for in situ measurement, where the light angle of incidence is defined by the construction of the CVD reactor chamber.…”

Section: Introductionmentioning

confidence: 99%

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Laser Reflectance Interferometry System with a 405 Nm Laser Diode for in Situ Measurements of CVD Diamond Thickness

Kraszewski¹,

Bogdanowicz²

2013

Metrology and Measurement Systems

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In situ monitoring of the thickness of thin diamond films during technological processes is important because it allows better control of deposition time and deeper understanding of deposition kinetics. One of the widely used techniques is laser reflectance interferometry (LRI) which enables non-contact measurement during CVD deposition. The authors have built a novel LRI system with a 405 nm laser diode which achieves better resolution compared to the systems based on He-Ne lasers, as reported so far. The system was used for in situ monitoring of thin, microcrystalline diamond films deposited on silicon substrate in PA-CVD processes. The thickness of each film was measured by stylus profilometry and spectral reflectance analysis as a reference. The system setup and interferometric signal processing are also presented for evaluating the system parameters, i.e. measurement uncertainty, resolution and the range of measurable film thickness.

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In situ laser reflectance interferometry measurement of diamond film growth

Cited by 33 publications

References 16 publications

High-speed, high-accuracy optical measurements of polycrystalline silicon for process control

High-speed, high-accuracy optical measurements of polycrystalline silicon for process control

Morphology and Electron Emission Properties of Nanocrystalline CVD Diamond Thin Films

Laser Reflectance Interferometry System with a 405 Nm Laser Diode for in Situ Measurements of CVD Diamond Thickness

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