摘要:

Interaction of a focused continuous wave laser beam with integrated circuits leads to various chemical reactions according to the nature of the irradiated interface and to the surrounding atmosphere. Silicon, tungsten, and nickel were locally deposited using silane, tungsten fluoride, or nickel carbonyl, respectively. The kinetics of these chemical reactions have been investigated and compared to the results of an appropriate kinetic model for surface reactions. Various chemical reactions for surface etching have also been investigated, such as etching of aluminum or silicon dioxide which occur at high temperature. Cutting interconnections, etching insulator layers, or depositing new chemical connections are the main applications of the laser–gas–surface chemical interaction, which is being more and more widely used for micron size features.

ISSN:1071-1023    

DOI:10.1116/1.586342

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The value and applicability of scanning tunneling microscopy (STM) studies for investigating the structure and growth of thin metal films is demonstrated in model studies on two epitaxial systems, Cu/Ru(0001) and Au/Ru(0001). STM imaging gives direct access to the microscopic features of thin film growth and by following the film morphology with coverage and observing the variations with changes in the growth conditions, information on the kinetics of nucleation, diffusion barriers, and two‐dimensional growth mechanisms were obtained. High resolution imaging allowed the atomic structure within the overlayers to be investigated, revealing their characteristic defects, and their mechanisms of stress accommodation between subsequent layers. These data are compared with results of earlier studies using nonlocal, averaging techniques and the often indirect conclusions drawn from those measurements.

ISSN:1071-1023    

DOI:10.1116/1.586343

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The low pressure chemical vapor deposition of copper and platinum is studied on SiO2substrates which have been locally prenucleated with ultrathin metal layers of Pt, Cu, Pd, Au, and W. These layers were between 0.1 and 30 Å thick and were produced by vacuum evaporation. Copper metal is deposited selectively on top of the prenucleation layers from the gaseous bis‐hexafluoroacetylacetonate {Cu(hfa)2} diluted in hydrogen. High quality copper could be grown at temperatures in the range of 300–400 °C with electrical resistivities as low as 2.5 times the bulk copper value. In contrast, platinum deposited from gaseous Pt(hfa)2in H2grows selectively on the clean oxide surface rather than on the areas prenucleated with vacuum evaporated platinum.

ISSN:1071-1023    

DOI:10.1116/1.586344

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Rotationally anisotropic surface second‐harmonic generation (SHG) has been used to investigate the surface structure and thermal stability of a clean, well‐characterized Cu(110) single crystal surface in ultrahigh vacuum. The results show clear evidence of the sensitivity of optical SHG to changes in surface structure. At a fixed Cu(110) sample azimuthal angle, the temperature dependence of the second‐harmonic radiation field from the surface was measured at two different wavelengths and found to be in agreement with other experiments performed using very different surface probes that show a sharp change in slope above ∼600 K associated with a possible order–disorder transition. The rotationally anisotropic SH intensity from Cu(110) was found to dramatically decrease as the surface temperature was increased above ∼600 K indicating a loss of surface order and symmetry. A simple model is proposed where thermally induced one‐dimensional disordering accounts for all of the experimental observations between ∼600 and ∼800 K, and where the Cu(110) surface has thermally disordered in two‐dimensions above ∼800 K.

ISSN:1071-1023    

DOI:10.1116/1.586345

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Synchrotron radiation‐assisted etching of SiO2in a hydrogen atmosphere and its application to pretreating and cleaning substrates prior to Si film deposition is discussed. Thermally oxidized SiO2film is etched in irradiation by synchrotron radiation at about 500 °C. Its etch rate increases by a factor of two in a hydrogen atmosphere. SiO2core electron excitation by such irradiation seems to play an important role in SiO2film modification and etching. This treatment reduced the interface contaminants such as oxygen and carbon between the deposited film and substrate to levels below the detection limit of secondary ion mass spectroscopy. Our results demonstrate that this new process is effective for low‐temperature treatment.

ISSN:1071-1023    

DOI:10.1116/1.585856

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The resolution requirements for nanolithography can be satisfied; both devices and small‐scale circuits with features well below 100 nm have been fabricated. However other requirements such as adequate throughput (about 1 cm2/s) and a precision on feature edge placement of the order of 10 nm over 20 mm remain as serious challenges. Evolving technology may allow us to extend present‐day technology such as deep ultraviolet lithography towards 100 nm feature sizes. But to go below that size radically new approaches will probably be needed. Examples include x‐ray printing and some form of adaptive alignment in which relative distortion between mask and wafer is tracked.

ISSN:1071-1023    

DOI:10.1116/1.586346

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The main strategies for shallow doped layer formation in semiconductors are outlined and the physicochemical characteristics of two of these, direct implantation and diffusion from overlayers, are described. The changing implementation of these techniques is discussed in the context of bipolar and metal–oxide semiconductor silicon integrated circuit fabrication technologies as these have progressed to submicron geometries and ultra‐large‐scale integration densities. The crucial shallow one and two dimensional doped regions thus fabricated are presented as important and difficult challenges for state‐of‐the‐art compositional analysis techniques.

ISSN:1071-1023    

DOI:10.1116/1.586348

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

We review measurements of abrupt transitions in III–V compound semiconductors and heterostructures, including abrupt interfaces as found in quantum wells (QWs) and high electron mobility transistors (HEMTs), and abrupt doping profiles such as delta doping. The interface quality of QW and HEMT structures can be studied using photoluminescence (PL). Several methods are employed to characterize the abrupt doping profiles of delta‐doped structures. Hall and Shubnikov–de Haas measurements are used to extract the 2D carrier concentrations in detail.C–Vprofiling is employed to study the carrier profiles normal to the dopant plane. The actual dopant distribution can be obtained by secondary ion mass spectrometry or by combiningC–Vprofiling with theoretical calculations. The resolution of these measuring techniques will be discussed.

ISSN:1071-1023    

DOI:10.1116/1.586349

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Accurate determination of dopant and carrier distributions for ultra‐large‐scale integrated devices poses stringent requirements to the analysis tools used. In assessing their potential one has to investigate their properties with respect to near‐surface quantification, depth resolution, quantification for multilayers as well as the aspects of reproducibility, sensitivity, and generality in the application. In this article these aspects are discussed for the dopant profiling techniques Rutherford backscattering spectroscopy, secondary ion mass spectrometry, and the carrier profiling methods spreading resistance profiling, capacitance–voltage, scanning tunneling microscopy, and transmission electron microscopy.

ISSN:1071-1023    

DOI:10.1116/1.586350

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The most fundamental physical processes which limit the depth resolution achieved in depth profiling by sputtering and surface analysis techniques are surface microroughening and atomic mixing in the collisional cascade. A survey of theoretical modeling of cascade mixing and its effect on the shape of measured profiles is presented. In particular, diffusion type models show reasonable agreement with recent experimental results of secondary ion mass spectroscopy and Auger electron spectroscopy profiles on delta function marker layers and on multilayer sandwich structures. The mixing range is related to the range of the primary ions and determines the depth resolution. Minimum values obtained under optimized sputtering conditions are of the order of 1 nm. Depending on the gradient of the true in‐depth distribution of composition, deconvolution procedures may become necessary to disclose the latter. Because sputtering is based on cascade mixing, the ultimate achievable resolution in depth profiling is limited by this effect.

ISSN:1071-1023    

DOI:10.1116/1.586352

出版商:American Vacuum Society    

年代:1992

数据来源: AIP