摘要:

Atomic layer epitaxy (ALE) is emerging as a promising epitaxial growth technique for thickness control at the atomic level. The article outlines recent progress in ALE of III–V and Si thin films. Also models describing the self‐limiting processes will be outlined.

ISSN:0734-211X    

DOI:10.1116/1.587179

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The subject of this review is the secondary ion mass spectrometry (SIMS) analysis of ultrathin or delta layers of impurity in a semiconductor matrix and their use in establishing the limitations of SIMS depth profiling, exploring the fundamental processes occurring during analysis, and enhancing the quantification of SIMS data. Methods for extracting accurate information for the grower (concerning the material) and the analyst (concerning the SIMS instrument) are described. It is demonstrated that sets of SIMS profiles obtained over a range of analytical conditions are desirable if accurate information is required. In this context, the observation of dopant interaction occurring in codoped samplesduringSIMS analysis is reported for the first time. It is shown that quite large discrepancies exist between different measurements of decay length and associated parameters for the same impurity/matrix combination. These need to be explained before attempting to relate delta profile shape to primary ion beam induced mass transport mechanisms. The concept of the delta profile as a response function and the use of deconvolution as a complete quantification method are discussed. The use of delta profiles in setting up models of the ion–solid interaction such as IMPETUS is illustrated.

ISSN:0734-211X    

DOI:10.1116/1.587180

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

This article describes the influence of the angle of incidence of the interaction of oxygen ions with GaAs surfaces and the effects these interactions have on compositional quantification by secondary ion mass spectrometry. Both Auger electron and small spot size x‐ray photoelectron spectroscopies were used to study the chemistry of the bombarded surfaces. The oxidation states of gallium and arsenic and the overall gallium‐to‐arsenic ratios were found to vary in a systematic way with angle of incidence. Changes in gallium and arsenic surface chemistry are correlated with secondary ion yields of dopants or impurity atoms.

ISSN:0734-211X    

DOI:10.1116/1.587181

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Secondary ion mass spectrometry (SIMS) and electron spectroscopy for chemical analysis were used to study SiO2/Si3N4/SiO2(ONO) structures. The purpose was to determine if the nitrogen tail seen going into the silicon substrate was real or an artifact of ion bombardment. To determine this without an element of doubt, samples were thinned from the backside to the ONO layer and SIMS depth profiling was carried out on the exposed underside of ONO. Profiling from the backside shows there is no nitrogen tail in the silicon substrate and there isnonitride at the oxide/Si interface, as seen from front side profiling. The effects seen during profiling from the front side are due to anomalous diffusion of nitrogen caused by ion bombardment. It is believed that nitrogen–oxygen complexes are formed in the silicon substrate as a result of nitridation, and this adversely affects device performance. Though this may still be true, one needs to be cautious in interpreting SIMS and Auger depth profiles from the front side in order to corroborate the electrical results.

ISSN:0734-211X    

DOI:10.1116/1.587183

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Implantations of49BF+2ions at 35 and 50 keV have been performed in thin films of cobalt and the resulting11B+profiles have been measured by low energy secondary ion mass spectrometry (SIMS). Careful crater depth measurements as a function of sputtering time revealed that under 3.0 keV32O+2ion bombardment the erosion rate at the surface was ∼70% higher than that in the ‘‘bulk.’’ A correction procedure was applied for determining the true depth of the measured boron distributions, and values of the projected range and the parallel straggling were extracted from the SIMS profiles. By using measured range data for boron in Si, Bragg’s rule was applied for calculating the corresponding values for boron distributions in CoSi2. The results are compared with measured profiles in CoSi2thin films and theoretical predictions based on Monte Carlo simulations.    

ISSN:0734-211X    

DOI:10.1116/1.587184

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) is an efficient, sensitive method for characterizing semiconductor surfaces. In addition, TOF‐SIMS can be applied in a depth profiling mode allowing qualitative characterization of the top 20 nm of material. The utility of TOF‐SIMS ultra‐shallow depth profiling is demonstrated on GaAs substrates that were passivated with P2S5solutions and oxidized by exposure to an UV/ozone treatment.

ISSN:0734-211X    

DOI:10.1116/1.587143

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

An optimized secondary ion mass spectrometry (SIMS) technique was used to characterize the solid source diffusion of dopants, i.e., arsenic and boron, from agglomerating cobalt disilicide sources. It was found that interface roughness plays a dominant role in determining the dopant profiles observed by SIMS. Double convolution of a step function with an exponential function, which represents the SIMS cascade mixing, and then again with a Gaussian function, which represents the silicide interface roughening, were performed to fit the SIMS silicon signal in the transition region of the silicide/silicon interface. Experimental profiles were then deconvoluted with the same functions to derive the ‘‘true’’ dopant diffusion. This convolution methodology eliminates the broadening factors provided by the measuring instrument and by the sample itself, and therefore results in a more physically meaningful diffusion profile. The broadening of SIMS silicon signal also provides a very precise characterization of the thermal stability of the thin polycrystalline silicide film. An analytical model was established to relate the SIMS silicon broadening and the sheet resistance of the agglomerated silicide film. This model predicts that while the amplitude of the root‐mean‐square roughening goes as the square root of time, the increase in sheet resistance varies linearly with time, provided that the amplitude of roughening is considerably smaller than the thickness of the silicide film.

ISSN:0734-211X    

DOI:10.1116/1.587144

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Performing secondary ion mass spectrometry (SIMS) depth profiles with high depth resolution,<10 nm, through silicided polysilicon contacts is made difficult by the inherent roughness of the silicide/poly interface. This interface roughness results in a loss in depth resolution and leads to the subsequent broadening of the dopant profile under the silicide. In some instances, where the junction is less than 100 nm, it is not possible to obtain an accurate and reliable depth profile of the dopant in the poly or the substrate Si. In this article, the practical application of polishing techniques for planarization and subsequent high depth resolution SIMS analyses are presented. This article will focus on the application of this technique to silicided poly contacts over diffusion areas.

ISSN:0734-211X    

DOI:10.1116/1.587145

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A method is presented allowing the lateral dopant distribution in the vicinity of the edge of a linear implantation (or diffusion) mask of specific test samples to be measured. Basically, the sample is sectioned perpendicularly to the surface, and parallel to the mask edge. The dopant distribution into the depth of this section (i.e., parallel to the surface of the wafer) is then measured with secondary ion mass spectrometry (SIMS), making use of its excellent depth resolution. The concept of this approach, its requirements, the sample preparation, and first results obtained on ion‐implanted arsenic in silicon are presented and discussed. Limiting effects involved in this approach are identified, and a potentially useful extension of the method toward the measurement of thetwo‐dimensional dopant distribution (2D SIMS) is discussed. The results of the measurements on ion‐implanted arsenic appear to be sufficiently accurate to provide a valuable input for comparison with computer simulation results.

ISSN:0734-211X    

DOI:10.1116/1.587146

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A two‐dimensional secondary ion mass spectrometry dopant profiling technique, using a specially prepared sample, has been used to provide high spatial resolution, high sensitivity, dopant maps of boron and arsenic. These have been compared with TSUPREM(IV) simulations. However, investigation of the disagreements between the modeled and experimental data cannot be made, as a major problem has been accurately determining the position of the mask edge on the reconstructed profile. Previous methods have introduced errors of up to 0.2 μm. This has been overcome by using a low energy, low dose, germanium implant as a marker of the mask window. The effect of this marker implant on the dopant distribution to be measured has been investigated and estimates of the accuracy of locating the mask edge have been made using the TSUPREM(IV) code. It is expected that the mask edge in later profiles will be located to better than 15 nm.

ISSN:0734-211X    

DOI:10.1116/1.587147

出版商:American Vacuum Society    

年代:1994

数据来源: AIP