摘要:

Secondary ion mass spectrometry (SIMS) relative sensitivity factors (RSFs) are tabulated for atomic and molecular ions sputtered from Si and GaAs matrices using oxygen primary ions and positive secondary ions. The RSFs are inversely proportional to the secondary ion yields. RSFs are plotted versus atomic number to establish patterns and trends. The data for molecular ions aid in the resolution of certain mass interferences and also have implications for the SIMS ionization process.

ISSN:0734-2101    

DOI:10.1116/1.577174

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Electron cyclotron resonance plasma (f=2.45 GHz, microwave powerP=200–800 W) generated in a radially uniform magnetic field (B=875–1000 G) was used to produce a large area (15–20 cm diam) uniform plasma stream at 20–30 cm from the source output. Low temperature (70–300 °C) silicon nitride films with a thickness of 800–3000 Å were deposited on 5–20 cm diameter wafers with deposition rates of 100–350 Å/min. Film thickness uniformity was ±1% for 7.6–10.0 cm diam wafers, ±3% for 15 cm diam wafers, and ±9% for 20.0 cm diam wafers. It was found that the film deposition rateWgincreased linearly with the silane flow rate, whileWgincreased slower than power 1/2 with the nitrogen flow rate. The film refractive index was 1.9–2.0 at a silane/nitrogen flow rate ratio of 0.40–0.6. The effects of plasma density and its profile on the film growth rate and uniformity are discussed.

ISSN:0734-2101    

DOI:10.1116/1.577175

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The electron trapping phenomenon ina‐SiN:H films deposited by radio frequency (rf) glow discharge has been studied as a function of rf power and gas feed ratio. The chemical composition of the films was determined with Fourier transform infrared spectroscopy. The nitrogen content of the films increased with rf power level if the feed ratio of silane to ammonia was sufficient, 1:10. A gas ratio of 1:5 lacked sufficient ammonia fraction to yield nitrogen rich films despite an increase in rf power level. The electrical resistivity increased and in general electron trapping decreased with increasing nitrogen content in thea‐SiN:H films. There is weak experimental evidence that an electron trapping minimum is obtained at a film composition similar to stoichiometric silicon nitride. The measured coordination number of 2.4 for films at this stoichiometric ratio corresponded to the optimum coordination number for a random covalent network. This conceivably should yield the lowest trap density material. At this time, however, it is safer to conclude that electron trapping decreases with increasing nitrogen content in the material.

ISSN:0734-2101    

DOI:10.1116/1.577176

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Modeling is performed for focused‐ion‐beam (FIB) sputtering and redeposition on trench sidewalls in a steady state approximation. Calculations are carried out to demonstrate the sputtered surface profile under known parameters such as sputtering yield as a function of ion incident angle, the FIB current density profile, and the FIB scan speed. It is found that a steplike slope with a gradient angle of θ0is formed at the FIB bombarding position. Furthermore, the redeposition flux on the sidewalls is calculated as a function of θ0for the FIB trench milling assuming the cosine law for the angular distribution of the sputtered atom. The redeposition will be more accurately predictable and controllable when more information about these assumptions is obtained.

ISSN:0734-2101    

DOI:10.1116/1.577177

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Mean ion energy and ion flux have been investigated in a low‐pressure, radio frequency (rf) magnetron discharge (dual rf excitation plasma) as function of substrate rf power and frequency, plasma excitation rf power and process pressure. Electrical and Langmuir probe measurements were used to determine the self‐bias of the electrodes and time‐averaged plasma parameter, respectively. The energy and flux of ions bombarding the substrate surface can be accurately controlled in the low‐energy range (<50 eV) without affecting the state of the discharge by applying an appropriate rf bias power and frequency to the substrate electrode. A simplified sheath model is used to verify the experimentally obtained linear relationship between substrate rf power and self‐bias of the electrode. The ion flux to both electrodes as well as the mean ion energy to the plasma excitation electrode are controlled by the plasma excitation rf power. The increase in process pressure from 5 to 40 mTorr reduces the ion flux to the substrate without changing the mean ion energy. The plasma parameters and their spatial distribution are strongly affected by the magnetic field, which also determines the ion energy flux distribution on the substrate surface.

ISSN:0734-2101    

DOI:10.1116/1.577178

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The present study deals with the design aspects of planar magnetron sputtering targets. A permanent ring magnet with modified pole piece geometry has been used for maximum ionization efficiency. The efficiency of electron containment on the target surface has been evaluated in terms of current at the electrically isolated substrates. The details of the relation between the magnetic field strength and field geometry on the ionization currents and operating pressure have been discussed. The best among the designs studied, when operated at a pressure of 8×10−3Torr resulted in a deposition rate of about 2000 Å/min at a current density of 4 mA/cm2. The substrate temperature rise was about 20 °C under these conditions. The design details of the magnetrons, experimentation for evaluating the electron containment have been discussed in this article.

ISSN:0734-2101    

DOI:10.1116/1.577179

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

We have investigated the concentration of Agnclusters (25

ISSN:0734-2101    

DOI:10.1116/1.577180

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The effect of substrate bias on plasma parameters has been studied for an electron cyclotron resonance plasma under typical materials processing conditions. Substrate conditions include floating with respect to the plasma, negative dc bias, or capacitively coupled rf bias. It has been found that the dc‐bias can profoundly affect the electron density, the electron temperature, and the plasma potential, well into the bulk of the plasma. The rf bias is found to be generally less perturbative, though can still cause significant change in the plasma potential. Changing the rf bias frequency appears to alter the effects on the bulk plasma.

ISSN:0734-2101    

DOI:10.1116/1.577181

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The properties of plasmas created and sustained by electron cyclotron heating (ECH) have often been found to undergo an abrupt change as the ambient gas pressure is reduced below a value that is typically around 10−5–10−4Torr. A model is presented in which ambipolar transport of particles and energy are balanced by electron impact ionization and microwave power absorption, respectively. In the absence of magnetic‐mirror confinement of high energy electrons, the equilibria predicted by the model exist only for gas pressures greater than a value determined by the ionization rate constant, the average ion mass, and the axial length (along the steady magnetic field) of the discharge. At the critical pressure, the equilibria bifurcate into high‐temperature/low‐density and low‐temperature/high‐density branches. Magnetic‐mirror confinement of high‐energy electrons can lower the critical pressure and modify the bifurcation somewhat. In all cases the equilibrium electron temperature is governed primarily by gas pressure while the plasma density is proportional to the microwave power density absorbed by the plasma.

ISSN:0734-2101    

DOI:10.1116/1.577182

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

When ion milling is employed to change the contours of large area surfaces it is often assumed that the sputtering rate is directly proportional to the sputtering yield for normal ion incidence on to a plane surface. It is shown how this zero order approximation can lead to errors in expected contours and higher order approximations are analyzed to indicate how errors can be reduced by improved choice of sputtering parameters. The behavior of static, broad beam, and dynamic, swept focused beam systems are discussed.

ISSN:0734-2101    

DOI:10.1116/1.577183

出版商:American Vacuum Society    

年代:1991

数据来源: AIP