ISSN:1071-1023    

DOI:10.1116/1.589790

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

CHF3+BCl3reactive ion etching etching was used to study the etching ofInxGa1−xAsandInxAl1−xAslayers with varied In contents (x=0.18,0.3, 0.52). By addingCHF3gas, it is possible to effectively reduce the etching rate ofInxAl1−xAs,without any influence on theInxGa1−xAs.The etching rate ofInxGa1−xAsdecreased with the In content; however,InxAl1−xAsshowed the opposite trend. The etching selectivity between theInxGa1−xAsand theInxAl1−xAslayers was increased by reducing the In content.

ISSN:1071-1023    

DOI:10.1116/1.589791

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.589792

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

This article discusses the preliminary results obtained from an extensive spreading resistance probe (SRP) intercomparison conducted between 21 international laboratories with different levels of expertise both in the U.S. and in eight European countries. In the first phase, identical raw SRP model data and model calibration curves were sent around for six different structures. The carrier and resistivity profiles obtained from many different versions of software packages from three different manufacturers were analyzed. The observed variations are mainly dominated by radius variations and differences in applied mobility models. In the second phase, an extensive round robin was organized, involving the measurement of 22 separate samples including submicron source/drain and well implants and an ultrashallow sub-100 nm, 20 keV As implant. All samples were initially characterized by secondary ion mass spectrometry and four point probe mappings. The SRP repeatability and reproducibility for dose, sheet resistance, and junction depth obtained from a statistical analysis as defined by the International ISO 5725 standard are discussed as well as basic operational parameters such as bevel surface roughness, probe penetration, and bevel angle accuracy. All results indicate that there is a need for better international standardization of SRP operations.

ISSN:1071-1023    

DOI:10.1116/1.589793

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Using a magnetic sector field instrument we have performed a detailed study on profile artifacts produced when measuring very shallow boron doping distributions (0.5 keV11B) in silicon by oblique oxygen bombardment (1.9 keVO2+at 56°) in combination with oxygen flooding. The raw profiles were calibrated by standard procedures, i.e., by assuming a constant erosion rate and a constant B-to-Si sensitivity ratio. The11Bprofiles derived from measurements at high oxygen pressures (rapid “saturation” of theSi+reference signal) turned out to be shifted towards the surface by up to 4.5 nm compared to profiles recorded at base pressure. This shift is larger by a factor of 2 than the value previously reported for normally incidentO2+beams of the same energy without oxygen flooding. A particularly large artifact (7 nm shift) has been observed with profiles implanted into Si covered with a 6 nm surface oxide film. The profile shifts appear to be related to a significant (up to 40%) decrease of the matrix reference signals observed under high-pressure flooding conditions at (apparent) depths between about 10 and 50 nm. The ion yield reduction may be indicative of a rapid development of bombardment induced surface roughening, accelerated by oxygen flooding. An additional contribution to the profile shift may originate from the large change in erosion rate of the sample brought about by high-pressure oxygen flooding (reduction in erosion rate by up to a factor of 3.5). Last, but not least, evidence is presented that the concept of stable B-to-Si sensitivity ratios breaks down in the transient region. These findings imply that the oxygen flooding technique in combination with oblique oxygen bombardment is not suited for quantitative depth profiling of shallow doping distributions.

ISSN:1071-1023    

DOI:10.1116/1.589794

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Low-energy boron implantations between 100 eV and 10 keV are characterized using secondary ion mass spectrometry and electrical measurements of sheet carrier concentrations and sheet resistance. Factors that may limit the use of ion implantation for future generations of semiconductor devices are discussed. At 1 keV various tilt angles show identical channeling behavior, and only a slight difference with an amorphous implant. It is found that as the energy is lowered from 1 keV to 100 eV much of the reduction in profile depth is canceled out by transient enhanced diffusion during a rapid thermal anneal. Hall–van der Pauw measurements show that with lower implant energy it becomes more difficult to activate the implanted dose. This is possibly due to increased clustering of boron, but more likely due to the fact that the surface starts to act as a trapping and deactivation center for B.

ISSN:1071-1023    

DOI:10.1116/1.589795

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Secondary ion mass spectrometry and spreading resistance profiling techniques have been used to measure dopant profiles and determine electrical activation in ion-implanted samples with effective ion energies as low as 112 eV (i.e., for 0.5 keVBF2). The analytical protocols will be discussed and used to compare the results for samples implanted with ion energies ranging from 0.5 keV (B andBF2) to 8.9 keV(BF2),with and without Ge preamorphization (with and without solid phase epitaxy anneals at 550 °C for 30 min), and finally annealed at 750–1050 °C for 10 s. Limitations of both analytical techniques for ultrashallow junction characterization and areas where improvements are required are discussed.

ISSN:1071-1023    

DOI:10.1116/1.589796

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We present high resolution secondary ion mass spectroscopy (SIMS) depth profiles for characterization of Si/SiGe/Si heterojunction bipolar transistors (HBT). We show by device simulation that to achieve transit frequencies of more than 90 GHz for a given HBT, it is necessary to keep the decay length of the B profile in the SiGe base layer smaller than 2.5 nm. This formulates stringent requirements for the processing technology and for profile characterization techniques. In time-of-flight secondary ion mass spectroscopy (TOF-SIMS) depth profiling (dual-beam mode), we used a low energy (0.5–3 keV) sputter gun operating with different sputter gases (Ar,O2,SF6) to achieve a profile decay length below 2.5 nm. The full width at half-maximum (FWHM) of 3 nm B doping spikes in HBT structures is well-characterized using anAr+ion beam of 1 keV. To measure B base doping with a decay length of about 1 nm it is necessary to lower the energy of the sputtering ion beam to less than 2 keV forSF6and to 0.6 keV for Ar sputtering. The decay length depends linearly on the sputtering ion beam energy in the low energy range. The slope of this dependence is smaller forSF6sputtering than for Ar sputtering.

ISSN:1071-1023    

DOI:10.1116/1.589797

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The use of oxygen flooding and an amorphous Si capping for secondary ion mass spectrometry (SIMS) depth profiling of ultralow-energy implants is discussed in terms of the accuracy of the depth and concentration scale. Further, the advantages of a lower primary ion energy and the simultaneous mass registration on a time-of-flight-SIMS with dual beam mode is illustrated. Finally, the effects of ultrahigh top concentrations on the tail of implantation profiles is investigated.

ISSN:1071-1023    

DOI:10.1116/1.589798

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The use of a normal incidence sub-keVO2+beam in secondary ion mass spectrometry (SIMS) depth profiling minimizes the widths of the transient regions at the surface of a shallow profile in addition to providing a very high depth resolution. At 300 eV we show that the transient width in silicon is<1 nm,and that the ion yields are relatively insensitive to the presence of native oxide. This suggests that ideal conditions for the profiling of very shallow implants are available at 300 eV and below. Nevertheless, the transient signals reflect differences in the thickness of native oxide, as well as differences in primary beam energy, and could, in principle, be used to measure process and wafer age related differences in the top few nm. We present one of the earliest attempts to accurately calibrate the depth in the pre-equilibrium region of a SIMS profile, taking account of the variation in erosion rate.

ISSN:1071-1023    

DOI:10.1116/1.589799

出版商:American Vacuum Society    

年代:1998

数据来源: AIP