In-situ RF diagnostic for PECVD process control

1997 ◽  
Vol 502 ◽  
Author(s):  
S. Raoux ◽  
K. S. Liu ◽  
X. Guo ◽  
D. Silvetti
Keyword(s):  
Process Control ◽  
Gas Flow ◽  
Input Parameter ◽  
Chemical Vapor ◽  
Single Frequency ◽  
Electrode Spacing ◽  
Electrical Characteristics ◽  
Dual Frequency ◽  
Statistical Process

ABSTRACTThe fabrication of advanced integrated circuits requires increased accuracy in process monitoring and active control. As higher production yields are required, the technology is moving from statistical process control to in-situ diagnostic techniques. A set of experiments was conducted to explore the feasibility of using radio frequency (RF) impedance probes to detect deviation of electrical characteristics of process chambers during wafer fabrication. A probe was integrated on a plasma-enhanced chemical vapor deposition (PECVD) chamber to explore the sensitivity of the reactor electrical characteristics on the events of process drift or input parameter variation. We measured RF the voltage, current and harmonics, the phase angle and the impedance magnitude for a capacitively coupled reactor. A single frequency (13.56MHz) process for depositing Si0 2 and a dual frequency (13.56MHz+35OkHz) process for Si3N4 deposition were characterized. We investigated the dependence of the RF signature and process parameters such as RF power, pressure, gas flow and electrode spacing. We observed that there is a correlation between the film properties (especially stress) and the plasma electrical characteristics. Furthermore, RF probes can be used to detect chamber malfunctions such as lost of RF ground or wafer-out-of-pocket events.

scholarly journals Conductivity tomography at two frequencies

Geophysics ◽  
2003 ◽  
Vol 68 (2) ◽  
pp. 516-522 ◽  
Author(s):  
Junxing Cao ◽  
Zhenhua He ◽  
Jieshou Zhu ◽  
Peter K. Fullagar
Keyword(s):  
Single Frequency ◽  
Dual Frequency ◽  
Frequency Range ◽  
Frequency Method ◽  
New Approach ◽  
Electromagnetic Absorption ◽  
Universal Approach ◽  
Approximate Frequency ◽  
Transmitting Antenna

We present a new approach for crosshole radio tomography. Conductivity images of the investigated area are reconstructed from the ratio of the electric field intensities measured at two similar frequencies. The method largely avoids assumptions about the radiation pattern and in‐situ intensity of the transmitting antenna, which introduce errors in conventional single‐frequency crosshole electromagnetic‐absorption tomography. Application of the method to field data achieved an improvement in resolution of anomalies over traditional single‐frequency absorption tomography. The dual‐frequency method is not a universal approach; it is suitable for moderately conductive media (<0.01 S/m) over the approximate frequency range 1–100 MHz.

In situ Chemical Vapor Deposition of Silicon

1974 ◽  
Vol 32 ◽  
pp. 488-489
Author(s):  
J. L. Kenty
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Metal Films ◽  
Cross Sectional ◽  
Environmental Cell ◽  
Si Films ◽  
A Current

An AEI EM6 electron microscope was modified for the in situ chemical vapor deposition (CVD) of Si films by pyrolysis of SiH4 gas. The environmental cell was so constructed that 100 μm dia. apertures placed 1.6 mm apart formed the top and bottom of the CVD microchamber and permitted a gas flow of up to 0.4 cm3 (STP)/min at up to 10 torr. A current of 2 amps through a single 200 mesh Ti grid of 0.003 mm2 net cross sectional area is sufficient to heat the sample to ~1200°C. Some temperature-heater power calibration experiments were performed by observing the melting point of evaporated metal films.

scholarly journals Retrieval of snowflake microphysical properties from multi-frequency radar observations

2018 ◽  
Author(s):  
Jussi Leinonen ◽  
Matthew D. Lebsock ◽  
Simone Tanelli ◽  
Ousmane O. Sy ◽  
Brenda Dolan ◽  
...  
Keyword(s):  
Single Frequency ◽  
Parameter Estimates ◽  
Dual Frequency ◽  
Snow Density ◽  
Radar Observations ◽  
Microphysical Properties ◽  
Triple Frequency ◽  
Multiple Frequencies ◽  
The Difference

Abstract. We have developed an algorithm that retrieves the microphysical properties of falling snow from multi-frequency radar observations. This work builds on previous studies that have indicated that three-frequency radars can provide information on snow density, potentially improving the accuracy of snow parameter estimates. The algorithm is based on a Bayesian framework, using lookup tables mapping the measurement space to the state space, which allows fast and robust retrieval. In the forward model, we calculate the radar reflectivities using recently published snow scattering databases. We demonstrate the algorithm using multi-frequency airborne radar observations from the OLYMPEX/RADEX field campaign, comparing the retrieval results to hydrometeor identification using ground-based polarimetric radar, and also to collocated in situ observations made using another aircraft. Using these data, we examine how the availability of multiple frequencies affects the retrieval accuracy, and test the sensitivity of the algorithm to the prior assumptions. The results suggest that multi-frequency radars are substantially better than single-frequency radars at retrieving snow microphysical properties. Meanwhile, triple-frequency radars can retrieve wider ranges of snow density than dual-frequency radars, and better locate regions of high-density snow such as graupel, although these benefits are relatively modest compared to the difference in retrieval performance between dual- and single-frequency radars.

Advanced epitaxial Si and GexSi1−x multiprocessing for semiconductor device technologies

1990 ◽  
Vol 5 (6) ◽  
pp. 1159-1162 ◽  
Author(s):  
Mehrdad M. Moslehi ◽  
Cecil J. Davis
Keyword(s):  
Gas Flow ◽  
Microwave Plasma ◽  
Semiconductor Device ◽  
Chemical Vapor ◽  
Surface Cleaning ◽  
Growth Surface ◽  
Chemical Cleaning ◽  
Process Energy ◽  
Rate Ratios

A single-wafer multiprocessing technology has been developed based on the use of lamp heating and remote microwave plasma process energy sources for fabrication of in-situ-doped homoepitaxial Si and heteroepitaxial Si/GexSi1−x multilayer structures via chemical-vapor deposition. Some effective low-temperature (650°–800°C) processes were developed for in-situ pre-epitaxial growth surface cleaning. These chemical cleaning processes employ GeH4 + H2 or GeH4 + H2 + (HF or HCl) gas mixtures with very small GeH4-to-H2 gas flow rate ratios. Multilayer heteroepitaxial structures with controlled doping and Ge fractions consisting of strained Ge4Si1−x layers were fabricated and characterized.

Experimental and Numerical Validation of Digital, Electromechanical, Parametrically Excited Amplifiers

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Amit Dolev ◽  
Izhak Bucher
Keyword(s):  
Theoretical Model ◽  
Single Frequency ◽  
Nonlinear Feedback ◽  
Dual Frequency ◽  
Detailed Model ◽  
Digital Implementation ◽  
Modeling Uncertainties ◽  
Wide Range ◽  
Sinusoidal Input

A parametric amplifier having a tunable, dual-frequency pumping signal and a controlled cubic stiffness term is realized and investigated experimentally. This device can be tuned to amplify a desired, single frequency weak signal, well below resonance. The transition between a previously described theoretical model and a working prototype requires an additional effort in several areas: modeling, design, calibration, identification, verification, and adjustment of the theoretical model. The present paper describes these necessary steps and analyzes the results. Tunability is achieved here by adding a digitally controlled feedback, driving a linear mechanical oscillator with an electromechanical actuator. The main advantage of the present approach stems from the separation of the controlled parametric and nonlinear feedback terms which are linked to the resonating element. This separation allows for the realization of feedback in an electronic form where a digital implementation adds further advantages as the feedback coefficients can be tuned in situ. This arrangement benefits from the mechanical resonance of a structure and from the ability to set the parametric excitation such that it accommodates sinusoidal input signals over a wide range of frequencies. The importance of an in situ identification phase is made clear in this work, as the precise setting of model and feedback parameters was shown to be crucial for successful application of the amplifier. A detailed model-identification effort is described throughout this paper. It has been shown through identification that the approach is robust despite some modeling uncertainties and imperfections.

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