摘要:

Oxide masked polysilicon/polygermanium 0.18 μm gates were etched in high density plasma sources. Using gas mixtures ofCl2and HBr withO2which are commonly used for polysilicon, we observed strong deformation of the poly-Si/poly-Ge gate profiles, whereas perfectly anisotropic etching profiles were obtained for poly-Si gates. A multistep etching recipe was developed allowing anisotropic etching profiles to be obtained while maintaining a good selectivity to the gate oxide when using aCl2/N2gas mixture. The chemical constituents present on the tops, sidewalls, and bottoms of the etched features were determined by x-ray photoelectron spectroscopy (XPS). XPS analyses have shown that when using aCl2/N2gas mixture, a thinGeNxpassivation layer is formed on the sidewalls of the poly-Ge features.

ISSN:1071-1023    

DOI:10.1116/1.590094

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The temperature dependence of the via hole etch rate is reported for argon/chlorine plasma etching of indium phosphide in an electron cyclotron resonance etcher. The indium phosphide via hole etch rate was first established for several wafer chuck temperatures. Then the temperature of the wafer was estimated by measuring the heating effect of the plasma and the cooling effect of the helium backside cooling. The wafer temperature was then substituted for the wafer chuck temperature. The etch rate as a function of wafer temperature was found to exist in two regimes. The first regime is where the vapor pressure of the etch by product gas (indium chloride) is below the etcher chamber pressure. In this first regime the activation energy was calculated to be0.45±0.05 eV.The second regime is where the vapor pressure of the etch by product gas (indium chloride) is above the etcher chamber pressure. In the second regime the activation energy was calculated to be0.06±0.03 eV.

ISSN:1071-1023    

DOI:10.1116/1.590095

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The effect of oxygen on polycrystalline-Si (poly-Si) andSiO2etching in hydrogen bromide (HBr) reactive ion etching plasmas has been studied by measuring etch rates and using x-ray photoelectron spectroscopy (XPS) to study compositional changes in the surface layer. The etch rate of the poly-Si increases dramatically from 30 to 235 nm/min as theO2concentration increases from 0% to 25%, whereas theSiO2etch rate gradually decreases from 3 to 1 nm/min. Above 30%O2in HBr, the poly-Si etch rate abruptly decreases by a factor of 16 compared with that at 25%. From XPS analysis, it is found that the abrupt decrease of the poly-Si etch rate atO2concentrations of more than 30% is closely related with the composition and thickness of anSiBrxOylayer formed during theHBr/O2plasma exposure. TheSiBrxOylayer has a composition of nearlySiO2.Br ions cannot permeate theSiBrxOylayer formed in plasmas containing 30%O2in HBr (or greater), and therefore, the poly-Si etch terminates.

ISSN:1071-1023    

DOI:10.1116/1.590096

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Nanocrystalline silicon films were deposited by radio frequency sputtering in a pureH2plasma on glass and monocrystalline 〈100〉 silicon at various substrate temperatures,Ts.The detailed structural, optical, and electrical analysis of the films has been performed by transmission electron microscopy, Raman scattering, infrared spectroscopy, x-ray diffraction, optical absorption, photoluminescence and electrical measurements. The data obtained show that, to a significant extent, control of the structure and hence of the optical and electrical properties of the films can be achieved by changingTs.IncreasingTsfrom 50 to 250 °C leads to an increase of the average grain size (from a few nm to a few tens of nm) and crystalline fraction (from 37% to 74%) and the optical band gap decreases from 2.40 to 1.95 eV. Hydrogen incorporation, together withTs,are thought to be at the origin of the resulting microstructure and consequently determine the optical and transport properties. Moreover, hydrogen content was found to be associated with void formation which induces structure relaxation with very low residual stress. Finally, electrical conductivity in the layers increases by more than six orders of magnitude withTs.The high dark conductivity measured from the sample deposited at the highestTs(>10−3 Ω−1 cm−1)and its low activation energy (0.13 eV) are in agreement with the high crystalline fraction of this layer, where tunneling of carriers between the crystallites likely occurs.

ISSN:1071-1023    

DOI:10.1116/1.590097

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We report on the use ofCHF3,C2F6,andSF6as etch gases for deep reactive ion etch processing of germano-boro-silicate glass films prepared by flame hydrolysis deposition (FHD). The glass film under study had a composition of 83 wt %SiO2,12 wt %GeO2,and 5 wt %B2O3.The scope of the study was to identify the benefits and drawbacks of each gas for fabrication of deep structures (>10 μm) and to develop an etch process in each gas system. The etch rate, etch profile, and surface roughness of the FHD glass films were investigated for each gas. Etch rates and surface roughness were measured using a surface profiler and etch profiles were assessed using a scanning electron microscope. It was found thatSF6had the highest FHD glass etch rate and nichrome mask selectivity (>100:1) however, it had the lowest photoresist mask selectivity (10:1) and the etch profile was found to be smooth and vertical.C2F6had a similar etch profile to that ofCHF3,but the selectivity over both mask materials was lower than inCHF3.Fused silica was used as a reference material where it was found the percentage drop in etch rate inC2F6, SF6, andCHF3was −12%, −15%, and −37%, respectively. From the results presented hereCHF3proved to be the most versatile etch process as either photoresist or nichrome masks could be used to attain depths of 20μm, or more.

ISSN:1071-1023    

DOI:10.1116/1.590098

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Chemically assisted ion beam etching (CAIBE) of InP-based materials has been newly developed withBCl3/Ar in comparison toCl2/Ar andIBr3/Ar. Using halogen gases and an argon ion beam at 400 V a very good surface morphology was obtained at a low substrate temperature of −5 °C in any case; withBCl3/Ar a surface roughness of 0.2 nm was observed. The etch rates were in the range of 40–75 nm/min depending on the reactive gas. Mixing the reactive gases or tilting the substrate with respect to the impinging ion beam allowed us an excellent control of the etched sidewall slope. By mixingBCl3andIBr3we were able to tune the sidewall slopes between 15° (measured to the surface normal) for pureBCl3and 38° for the pureIBr3, respectively. Tilting the substrate allowed us to adjust the slope angle between 0°and 60°. In addition we have analyzed the etched surfaces by energy dispersive x-ray measurements. The low temperature processes yielded stoichiometric InP surfaces, etching at higher substrate temperatures results nonstoichiometric surfaces. These low temperature halogen CAIBE processes were successfully applied for the fabrication of gratings, ridge waveguides and facets for long wavelength (InGa)(AsP) and (AlInGa)(AsP) laser diodes. In this article we present ridge waveguide (InGa)(AsP)/InP lasers (1.55μm) with direct CW modulation bandwidths of 9.5 GHz.

ISSN:1071-1023    

DOI:10.1116/1.590099

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The utilization ofCF3Iin the plasma assisted dry etching ofSiO2has been studied in order to reduce the environmental impact of microelectronics device fabrication. The results show thatCF3Iis a promising substitute ofCF4in oxide etching since its utilization reduces 3–3.5 times the contribution to the global warming, nevertheless it still has a consistent effect on the environment for the plasma assisted formation of perfluorocompounds.

ISSN:1071-1023    

DOI:10.1116/1.590303

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have employed current–voltage and capacitance–voltage measurements in conjunction with deep level transient spectroscopy to characterize the defects induced inn-Siduring rf sputter etching in an Ar plasma. The reverse current, at a bias of 1 V, of the Schottky barrier diodes fabricated on the etched samples decreased nonmonotonically with etch time to a minimum at 6 min and, thereafter, increased. The reverse current also increased with decreasing plasma pressure. The barrier heights of the diodes followed the opposite trend. Six prominent electron traps were introduced in the substrate during Ar sputter etching. A comparison with the defects induced during high-energy alpha-particle and electron irradiation of the same material revealed that sputter etching created the VO and VP centers andV2−/0.TheV2=/−charge state of the divacancy was not detected in our plasma etched samples. We have attributed the nondetection ofV2=/−to the presence of defect-induced stress fields in the etched samples. A secondary defect with an energy level atEc−0.219 eVwas introduced during annealing and was found to be stable at 650 °C. This defect was introduced at the expense of a sputter-etching induced defect P4, which has similar electronic and annealing properties as EAr201(Ec−0.201 eV),created in Ar-ion bombardedn-type Si.

ISSN:1071-1023    

DOI:10.1116/1.590100

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Low frequency noise and current–voltage measurements in several heavily doped polysilicon resistors of varying geometry and bothpandntype, and over a limited range of temperatures from −60 to 50 °C were conducted for the first time. We found that the noise inp-type polysilicon was independent of temperature, but not then-type polysilicon. For thep-type resistors, linear current–voltage characteristics were observed, and the relative noise spectral density was independent of bias and inversely proportional to frequency. For then-type resistors, linear current–voltage characteristics were observed, and the relative noise spectral density was independent of bias. Finally, the normalized noise level in the linearn-type resistors was almost an order of magnitude lower than for thep-type resistors. We believe that this difference is becausen-type dopants segregate to the grain boundaries, thus passivating some of the traps there. Boron(p-type dopant), on the other hand, does not segregate to the grain boundaries, leaving more unpassivated grain-boundary traps which capture and emit more carriers, resulting in more low frequency noise.

ISSN:1071-1023    

DOI:10.1116/1.590101

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The effects of glancing-angle argon ion bombardment on air-contaminated Si(001) surfaces were studied. Bombarding at substrate temperatureTs=730 °C, impingement angleφ=3–15°relative to the surface plane, ion energyE=1keV and doseD=3×1015ions cm−2gave high-quality reflection high energy electron diffraction (RHEED) patterns and contaminant-free surfaces as observed by ion scattering spectroscopy. Atomic force microscopy images showed roughness value⩽0.5 nm under these conditions, but the roughness increased and RHEED patterns became spotty for higher doses or energies. Secco etching of samples bombarded atTs=730 °C showed etch pits with a density of106–107cm−2that increased with increasingDandE. Room-temperature bombardment withE=1keV,D=3×1015ions cm−2andφ=3°, followed by a 730 °C anneal, yielded a lowest roughness value of 0.2 nm. Secco etching showed no resolvable pits, indicating a dislocation density<4×104cm−2.

ISSN:1071-1023    

DOI:10.1116/1.590102

出版商:American Vacuum Society    

年代:1998

数据来源: AIP