Leybold Inficon, Inc.

Inficon Gmbh

Abdul Wajid

Carl A Gogol, Jr

Clarence Hurd

Gary Rubloff

Melvin C Hetzel

A sound velocity sensor is defined by a hermetic multi-chambered enclosure for containing flowing gases and mixtures of gases. The contained flowing gases are acoustically excited and the acoustic energy is measured over a fixed distance between a first sending end of the enclosure and a receiving end. The speed of sound of the gases are determined by comparing the energy transmitted through the flowing gases at various frequencies so as to precisely determine the resonant frequency of the gases flowing through the enclosure. In accordance with the present design, the chambers of the enclosure include internal transition shapes therebetween for optimizing the transmission of acoustic energy through the flowing gases and also enhancing one or more additional resonant modes at higher useful frequencies. The transition shapes used in connection with the sensor can be at least one of parabolic, hyperbolic, linear and exponential in nature.

Multi-chambered acoustic sensor for determination gas composition

A method for accurately calculating the thickness of deposited thin film layers onto a piezoelectric crystal blank in which dissimilar materials can be utilized, enabling determinations for various applications employing exotic materials. Additionally, the specific acoustic impedance (or equivalent z-ratio) of an unknown deposited material can be determined. The exact analytical solution nearly eliminates thickness errors when several layers of different materials are sequentially deposited on the same monitor quartz crystal.

Method of determining multilayer thin film deposition on a piezoelectric crystal

A method of determining the reaction efficiency of a CVD process reactor by which a reactive gas combination entering the reactor deposits a solid reaction product as a thin film onto a substrate. The composition of the reactive gas combination is measured by an acoustic cell which is disposed downstream from the outlet port of the reactor to determine the reactor's efficiency. Determination of the reactor's efficiency allows the growth rate of the thin film to be determined as well as associated rates of the products which have been exhausted from the reactor.

Acoustic consumption monitor

An acoustic cell includes multiple acoustic cavities fluidly coupled together. At least two of the acoustic cavities have unequal lengths and cross sections. End segments of the acoustic cell are uniformly cylindrically shaped or conically shaped. A driver transducer at one end of the acoustic cell and a receiver transducer at another end of the acoustic cell are acoustically isolated from the acoustic cell. A pair of preferably metallic isolation diaphragms transmit acoustic signals to and from the transducers without significantly altering the phase-frequency characteristics of the acoustic signals. The acoustic cell operates as an acoustic resonator operating at frequencies lower than any possible self-resonance frequencies of the isolation diaphragms or the driver and receiver transducers. When a binary gas is flowed through the cell, a processor detects a resonant frequency of the gas within the cell to determine a composition of the gas.

Acoustic sensor for in-line continuous monitoring of gasses

An acoustic technique is employed to identify the species of a sample of refrigerant gas and whether it contains significant contaminants. The refrigerant is admitted into a Helmholtz resonator under controlled pressure, and a drive frequency is swept across a frequency band and applied to a first transducer. A second transducer picks up the vibrations in the resonator and the output signal is compared to the drive signal. The resonant peak or center frequencies are identified and the sharpness or quality factors are measured. These measured data are compared with stored data to identify the refrigerant.

Acoustic tool for analysis of a gaseous substance

An acoustic technique is employed to identify the species of a refrigerant gas and whether it contains significant contaminants. Air in the refrigerant can be tolerated, but must be accounted for in determining the acoustic properties of the sample. The refrigerant is admitted into a Helmholtz resonator under a controlled pressure, and a drive frequency is applied to a transducer. Another transducer picks up the vibrations in the resonator and an output signal is compared to the drive signal to find resonant peaks and sharpness factors. The change in resonant frequency with pressure is measured, and is employed to quantify the presence of air in the sample. The amount of air present determines a frequency correction, which permits unambiguous identification of the species of refrigerant and of its purity.

Quantitative determination of air present in refrigerant sample by

An AT-cut quartz crystal for a quartz crystal microbalance has a buffer layer sandwiched between an adhesion layer and an electrode layer on the front or deposition side of the crystal. The buffer layer can be a zinc layer of 6000 .ANG. sandwiched between a titanium or chromium adhesion layer of 100 to 160 .ANG. and a gold, silver, or aluminum outer electrode layer of about 2000 .ANG.. The zinc layer has a relatively low bulk modulus, and absorbs stress imposed by the deposited layer. The buffer layer prolongs useful crystal life, particularly when depositing dielectric materials. The crystal should have a modest surface roughness as keying-in structure.

Buffered quartz crystal

The thickness and rate of growth of a deposited film is monitored using a piezoelectric crystal sensor such as an AT-cut plano-convex crystal. The frequencies of the fundamental frequency and another resonance mode are measured prior to deposition, and the change of these two frequencies is monitored during deposition. The areal mass density of the deposited material is determined from these two resonance frequencies for the uncoated quartz crystal and for the crystal during deposition. A frequency generator provides accurate sweeps of frequency which are applied to the crystal, and the crystal response is supplied to a phase detector to identify the positions of the resonance frequencies. The acoustic impedance ratio Z of the deposited material relative to the fresh crystal is computed from the resonance frequencies for the coated and uncoated crystal, by applying the modal equations for AT-cut plano-convex quartz crystal and Lu-Lewis relation. From the frequency shifts and acoustic impedance ratio, and areal mass density can be calculated. The same crystal can be used to control the growth rate of several successive layers.

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East Syracuse, NY, United States of America

Abdul Wajid