Observation of an anomalously high etch rate in plasma-enhanced CVD silicon nitride films

ABSTRACTThe influence of ion bombardment on the mechanical stress and microstructure of sputtered silicon nitride (SiNx) films has been systematically investigated. Applied substrate bias voltage was used to control the bombardment energy in a radio frequency (rf) reactive magnetron sputtering system. The resultant films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), Rutherford backscattering spectrometry (RBS), stress and chemical etch rate measurements. As the bias voltage was increased, the internal stress in SiNx films became increasingly compressive and reached a value of about 18.3 × 109 dyne/cm2 at higher bias voltages. These correlated well with the transition of the film microstructure from a porous microcolumnar structure containing large void to the more densely packed one. The obtained results can be explained in terms of atomic peening by energetic particles, leading to densification of the microstructure. It was also found that the amount of argon incorporated in the film is increased with increasing bias voltage, whereas the oxygen content is decreased. The lowest etch rate in buffered HF solution, approximately 1.2 Å/sec, was observed with the application of a substrate bias of -50 V.

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Determination of the Etch Rate and the Refractive Index of Silicon Nitride Films with an Ellipsometer

Journal of The Electrochemical Society ◽

10.1149/1.2411092 ◽

1968 ◽

Vol 115 (2) ◽

pp. 227 ◽

Cited By ~ 3

Author(s):

A. N. Saxena ◽

O. Tkal

Keyword(s):

Refractive Index ◽

Silicon Nitride ◽

Etch Rate ◽

Silicon Nitride Films

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Effect of the hydrogen content in the optical properties and etching of silicon nitride films deposited by PECVD for uncooled microbolometers

MRS Proceedings ◽

10.1557/proc-862-a9.6 ◽

2005 ◽

Vol 862 ◽

Cited By ~ 2

Author(s):

R. Ambrosio ◽

A. Torres ◽

A. Kosarev ◽

M. Landa ◽

A. Heredia

Keyword(s):

Hydrogen Bonding ◽

Silicon Nitride ◽

Hydrogen Content ◽

Etch Rate ◽

Low Frequency ◽

Chemical Vapor ◽

Silicon Nitride Films ◽

Pressure Chemical ◽

Quantitative Results ◽

Deposited Films

AbstractWe have studied silicon nitride films a-SiN:H deposited at a substrate temperature of 350°C by means of the Low frequency (LF) PECVD from silane and nitrogen as stock gases. Film properties as hydrogen bonding and content, nitrogen content, refractive index and etch rate are reported and analyzed. Our deposited films show physical properties similar to those that are obtained deposition temperatures of 700°C by the low pressure chemical vapor deposition (LPCVD) technique. An investigation of bonding structures for the deposited films was performed, and quantitative results for hydrogen bonding based on Fourier Transform Infrared (FTIR) analysis are presented. It was observed that low hydrogen content in the films is in good correlation with low etch rate in 10% buffered HF solution, therefore these films present a material with good etch selectivity in respect to others materials (as phosphosilicate glass PSG, Al etc). Selectivity which makes these films very promising in surface micromachining for fabrication of sensors and device structures, e.g. microbolometers. Additionally, the Si-N bond at 830-840cm-1was analyzed because of its big absorption produced at 12μm; therefore these films can be used as absorber layers in uncooled microbolometres.

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Hydrogen in RF Reactive Magnetron Sputtered Silicon Nitride Films

MRS Proceedings ◽

10.1557/proc-284-21 ◽

1992 ◽

Vol 284 ◽

Cited By ~ 1

Author(s):

Chi-Hsien Lin ◽

J. B. Wachtman ◽

G. H. Sigel ◽

R. L. Pfeffer ◽

T. P. Monahan ◽

...

Keyword(s):

Silicon Nitride ◽

Etch Rate ◽

Hydrogen Gas ◽

Nitride Film ◽

Silicon Nitride Film ◽

Reactive Magnetron ◽

Diffusion Behavior ◽

Silicon Nitride Films ◽

Silicon Target ◽

Secondary Ion

ABSTRACTABSTRACT: Silicon nitride films (a-SixN1−x:H) have been prepared by rf reactive magnetron sputtering from a silicon target in a mixture gas of Ar, N2, and H2. The effects of the presence of hydrogen gas have been related to the refractive index, deposition rate, etch rate, and the Si-H and N-H bonding in the films. Hydrogen contents were measured by a quadrupole secondary ion mass spectrometer (SIMS) using deuterium implanted samples as reference standards. The deuterium implanted samples were annealed at 900°C for various periods of time to study the diffusion behavior of deuterium and hydrogen in a Si-rich and a nearly stoichiometric silicon nitride film.

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In Situ Spectroscopic Ellipsometry for the Real Time Process Control of Plasma Etching of Silicon Nitride

MRS Proceedings ◽

10.1557/proc-591-263 ◽

1999 ◽

Vol 591 ◽

Author(s):

I. G. Rosen ◽

T. Parent ◽

B. Fidan ◽

A. Madhukar

Keyword(s):

Silicon Nitride ◽

Real Time ◽

Plasma Etching ◽

Spectroscopic Ellipsometry ◽

Etch Rate ◽

Polarization State ◽

Non Invasive ◽

Silicon Nitride Films ◽

In Situ Sensor

ABSTRACTSpectroscopic ellipsometry (SE) is a commonly used non-destructive, non-invasive in-situ sensor for dry etching. SE measures the change in the polarization state of light reflected from a surface. Sample thickness is obtained by fitting a model to the experimental ellipsometry data. In this paper we describe the design, testing and evaluation of an SE based adaptive real time feedback controller for etch rate regulation in CF4/O2 plasma etching of silicon nitride films. The feedback variable is the current etch rate as determined from the in-situ SE measurements of the film's thickness. The controller compensates for drifts in etch rate which occur during a given etch, and adaptively adjusts for the run-to-run variability inherent to plasma processing. Experimental results are presented and discussed.

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Composition and Properties of PECVD Silicon Nitride Films Deposited from SiH4, N2, He Gases

MRS Proceedings ◽

10.1557/proc-219-787 ◽

1991 ◽

Vol 219 ◽

Cited By ~ 3

Author(s):

J. H. Souk ◽

G. N. Parsons ◽

J. Batey

Keyword(s):

Silicon Nitride ◽

Electrical Properties ◽

Etch Rate ◽

Charge Trapping ◽

Film Stress ◽

Bond Density ◽

Silicon Nitride Films ◽

Current Voltage ◽

Optical And Mechanical Properties ◽

Wet Etch

ABSTRACTAmorphous silicon nitride films deposited from a gas mixture of SiH4 and N2 with a large flow of He have shown many interesting characteristics. The films show a wide variety of electrical, optical, and mechanical properties with varying amounts of SiH4 and N2. The effect of N2 flow rate on film composition in N2-SiH4 processes is quite different from that of NH3 flow in NH3-SiH4 processes. The films were characterized by measurements of (1) Si-H and N-H bond density and bonded hydrogen content, both from infrared absorption, (2) Si/N ratio, (3) refractive index, (4) film stress, and (5) wet chemical etch rate and (6) electrical properties including current-voltage (I-V) and capacitance-voltage (C-V). We find that adding helium to the PECVD process enhances the incorporation of nitrogen in the film and an optimized flow of SiH4 improves the electrical properties. Films with optimum electrical properties with minimum charge trapping are obtained with N/Si ratio close to 1.33. These films have a small amount of Si-H and N-H bonds, and a low etch rate (> 100 A/min) in aqueous HF solution. The properties of these low temperature (250°C) PECVD nitrides have many similarities with LPCVD nitrides. Compared with films deposited from SiH4, NH3 mixture, these films exhibit very low wet etch rates and much lower H contents, but greater hysteresis in C-V characteristics.

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