摘要:

Potential application of a projection system with reduction optics to the patterned doping process has been demonstrated. A KrF excimer laser beam is projected on GaAs substrates enclosed in a SiH4gas ambient cell to achieve the Si doping with a field size of 5×5 mm2. At a laser fluence of 380 mJ/cm2, then‐type conduction layer with a surface carrier density of 2.27×1014cm−2in the semi‐insulating GaAs substrate and with an activation efficiency of ∼81% can be obtained. The minimum linewidth of 2.5 μm is discussed together with temperature profiles calculated by transient heat conduction in the substrate.

ISSN:1071-1023    

DOI:10.1116/1.584163

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

A novolac resin suitable for the bottom planarizing layer in multilayer resist systems is discussed from the standpoint of exposure wavelength absorption. Absorption by the bottom planarizing layer is crucial to reduce the reflected light from the resist–substrate interface. It was clarified that the absorption of phenol novolac resin was higher than that of the cresol novolac resin under the same baking conditions. From infrared and nuclear magnetic resonance analysis, it was found that carbonyl structures were formed in the novolac resin after baking. In addition, cross‐linking was found to occur at the methylene bridges in the phenol novolac resins. These factors seem to cause the absorption maxima to shift to a longer wavelength.

ISSN:1071-1023    

DOI:10.1116/1.584164

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Chemical vapor deposition of tungsten silicide (WSix) from WF6and SiH2Cl2[JB Price, S. Wu, Y.Chow, and J. Mendonca, Semicon West (1986)] at higher deposition temperatures (450–650 °C) than the conventional WF6and SiH4(250–400 °C) process has been characterized using a plasma enhanced, single‐wafer, cold‐wall, radiantly heated system with temperature control utilizing a thermocouple in contact with the backside of the wafer. Film properties such as silicon to tungsten ratio, fluorine and chlorine concentration, resistivity, and film stress were studied as a function of substrate temperature, reactant composition, and flow rates. The film composition was measured by Rutherford backscattering spectrometry. The silicon to tungsten ratio is a function of deposition temperature at a fixed flow (xvarying from 2.0–2.8 through the temperature range of 450–650 °C). The as‐deposited resistivity is also a strong function of deposition temperature. The chlorine and fluorine distributions in the WSixfilm were measured using secondary ion mass spectrometry. The fluorine concentration was found to be much lower than levels reported by conventional WF6/SiH4chemistry with as‐deposited values of 9×1015to 3×1018/cm3compared to 1.3×1020cm3by M. Fukumoto and T. Ohzone [Appl. Phys. Lett.50, 894 (1987)].

ISSN:1071-1023    

DOI:10.1116/1.584165

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

For practical titanium silicide device application the oxygen behavior in the solid phase interaction is important to study. The Ti/Si and Ti/SiO2interaction by the NH3plasma assisted thermal annealing and oxidation of Ti/SiO2and TiSi2/Si in a wet oxygen ambient were investigated by Auger electron analysis. The characteristic Auger spectral line shapes of Ti, O, and Si and their changes in compounds were measured. The experiment clearly demonstrated the oxygen snowplow effect during TiSi2and TiN growth, and a stable SiO2can be grown on TiSi2/Si directly or through a layer of TiO2.

ISSN:1071-1023    

DOI:10.1116/1.584166

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Several workers have recently begun using silane as a high‐rate, low‐temperature alternative to hydrogen for the reduction of WF6in the chemical vapor deposition of W. The deposition and film characteristics of both selective and blanket W using this new chemistry are explored in a radiantly heated single wafer system using closed‐loop temperature control with a thermocouple in direct contact with the backside of the wafer. Selective W deposition rates of up to 1.5 μm/min were measured over the temperature range 250–550 °C with blanket W rates typically 2–5× lower. Resistivity is in the 10–15 μΩ cm range at 300 °C for SiH4/WF6ratios of 0.2 to 1.0, while above 400 °C the range is 7.5–8.5 μΩ cm. Si content in the W films is quite low at 1016to 1017atoms/cm3. Adhesion to silicon is excellent at temperatures of 350 °C and above. Selective W using SiH4reduction for doped silicon contact fill shows none of the consumption or encroachment problems common to H2reduction, although selectivity is more sensitive. Contact resistance forp+andn+silicon contacts are comparable to aluminum controls and to previously published data. Blanket deposition into narrow geometries gives ≥90% step coverage and without keyholes in the 250–450 °C deposition temperature range. For low‐SiH4flows, deposition at 500 °C causes small keyholes, while at 550 °C even larger keyholes result. At higher SiH4flows, keyholes are typically not seen from 250 to 550 °C. The SiH4‐reduced films are much smoother as indicated by reflectivities that are 2–4×higher than for the H2‐reduced films.

ISSN:1071-1023    

DOI:10.1116/1.584167

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Detailed material and electrical characteristics of rapid thermally annealed (RTA) TiSi2on doped silicon are presented using transmission electron microscopy, Rutherford backscattering spectrometry, secondary ion mass spectrometry (SIMS), Auger analysis, and four‐point probe measurements. TiSi2films with varying sheet resistances were formed on lightly doped and heavily arsenic and phosphorus implanted 〈100〉 silicon by rf sputtering titanium and forming the silicide using two‐step flash anneals at different temperatures. It is shown that the silicide sheet resistance is a sensitive function of the silicon surface condition prior to titanium sputtering; in particular, silicide films formed on heavily implanted silicon had significantly higher sheet resistance compared to films formed under identical conditions on lightly doped prime silicon. The higher silicide sheet resistance resulted because of the surface damage created during arsenic and phosphorus implantation and higher silicon dopant concentration. The RTA silicide films showed excellent film properties across 4‐in.‐diam wafers with good thickness uniformity and minimal sheet resistance variations compared to furnace annealed samples. Detailed SIMS and Auger analyses showed minimal film contamination and negligible dopant redistribution for RTA silicided wafers.

ISSN:1071-1023    

DOI:10.1116/1.584168

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

This report describes the formation of a TiSi2strap in combination with the self‐aligned titanium silicide (salicide) technology. The TiSi2strap is formed by reaction of amorphous silicon (a‐Si) with the underlying Ti layer. It was determined that sputter deposition of the Ti anda‐Si had to be done in one deposition cycle, otherwise interface contamination would prevent the Ti–a‐Si reaction and give rise to extensive silicon diffusion from the active areas. Since TiSi2straps are formed over diffusion areas as well as over oxide surfaces, the influence of the substrate on the Ti/a‐Si reaction was determined. It was found that for straps deposited on oxide substrate the properties of the silicide layer formed were determined by the Ti/a‐Si atomic ratio. A titanium‐rich strap resulted in a high‐resistivity silicide layer due to TiSi compound formation. Stoichiometric straps formed low‐resistivity TiSi2layers with a thin‐TiN top layer and silicon‐rich straps also resulted in a low‐resistivity TiSi2layer but with a silicon enrichment at the surface. On a mono‐Si substrate no influence of the sputtered Ti/a‐Si atomic ratio could be found. Only low‐resistivity TiSi2layers were formed. In case of silicon‐rich Ti/a‐Si ratio the excess silicon disappears from the layer and regrows onto the Si substrate. The roughness of TiSi2straps, mainly observed for stoichiometric or silicon‐rich straps on oxide substrates, was found to be related to the presence of argon (and probably hydrogen) incorporated in the layer during sputter deposition. Special attention was paid to strap formation at oxide/diffusion area edges. Possible void formation by local silicon consumption could not be detected. Strap/TiSi2salicide transitions are also very smooth and showed no substrate defects.

ISSN:1071-1023    

DOI:10.1116/1.584169

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

A new power field effect transistor (FET) structure with selectively silicided gate and source regions is described. This structure simultaneously lowers the gate sheet resistance and source contact resistance. Vertical power double‐diffused metal‐oxide semiconductor field effect transistors fabricated using this technology have a specific on‐resistance of 0.53 mΩ cm2for devices capable of blocking 50 V in the off‐state. Devices with cell density as high as 4 million cells/in.2and die size as large as 200×220 mil have been successfully fabricated with excellent gate yield. These results represent the best ever reported forward conductivities for any type of power FET in the 50‐V reverse blocking range. Comparison of selectively silicided power FET’s with state of the art commercial nonsilicided FET’s indicates that the former have an order‐of‐magnitude lower gate sheet resistance, 8× smaller on‐resistance, and 2× smaller input capacitance.

ISSN:1071-1023    

DOI:10.1116/1.584170

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Morphologies and characteristics of the surface and interface of TaSi2/Si and TaSi2/poly‐Si structures reactively formed by furnace annealing and rapid thermal annealing (RTA) have been investigated thoroughly. Scanning electron microscopy and transmission electron microscopy (cross section) results show that the morphologies of the annealed samples were uneven, but the surface and interface of RTA samples were better than that of furnace annealed samples. The specific contact resistivity of TaSi2ton+‐Si substrates with Kelvin structure was measured. The contact resistivity increased as the annealing temperature increased, but was lower for RTA samples than for furnace annealed samples. Sheet resistance measurement, x‐ray diffraction, and Auger electron spectroscopy analysis techniques were used to monitor the formation of TaSi2films.

ISSN:1071-1023    

DOI:10.1116/1.584171

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Powder diffraction techniques are potentially extremely useful for the characterization of a variety of metallic thin films which are used as interconnection materials in very large scale integrated (VLSI) devices. Phase identification, texture determination, elastic strain measurement, and grain size distribution can, in principle, be obtained nondestructively. Although x‐ray techniques have long been applied to bulk materials for these purposes, conventional x‐ray equipment, particularly the widely used Bragg–Brentano powder diffractometer, is often unsuitable for use on these thin films. High‐angle reflections are extremely weak, strong texture renders many reflections inaccessible, and reflections from the silicon single crystal substrate can be a serious interference. The Seemann–Bohlin focusing geometry with a fixed low angle of incidence provides improved intensities and reduced substrate interference, but is unsuitable for texture determinations or strain measurements. We have designed a unique instrument, called a generalized focusing diffractometer (GFD), which combines the intensity advantages of a focusing geometry with the flexibility necessary for texture and strain measurements. The key capability is the arbitrary setting of the incidence beam angle α, independent of the Bragg angle 2θ, which allows accessing of practically any desired set of Bragg diffraction planes in the sample. The focusing condition is achieved in such a geometry by computer control of the sample to detector (receiving) slit distance. Four distinct modes of operation are possible with the GFD: Bragg–Brentano (BB), Seemann–Bohlin (SB), texture analysis (TA), and strain analysis (SA). The BB and SB modes are conventional, except that the incident beam angle α, can be varied arbitrarily in the SB mode, allowing small 2θ values to be explored. In the TA mode, the sample is rocked through a range of incidence angles while the detector is fixed in 2θ, but continuously positioned relative to the sample for optimal focus. In the SA mode, profile scans of particular Bragg reflections are obtained at varying beam incidence angles while the focusing conditions are continuously maintained bydetector positioning. Several examples illustrate the application of the GFD. Untextured powdered Si provides a comparison of BB and SB modes. A film of 5 nm of Au on a glass substrate with well‐developed (111) texture further illustrates the differences between these modes, and indicates the sensitivity of the GFD focusing geometry. A sample consisting of alternating layers of 50‐nm sputtered amorphous TiSi2and 500 nm of polycrystalline Al–Si on a Si substrate is examined in the BB and SB mode both as synthesized and after two thermal cycles at 450 °C. The scans indicate well‐developed texture in the Al–Si film and the thermally induced growth of silicide crystallites. A sample of highly textured 1000‐nm Al sputtered on Si is examined in TA mode to demonstrate this capability. Finally, SA scans on a sample of highly textured 750‐nm Al‐1% Sm sputtered on Si have been used to determine the strain in the thin film. The results are compared with those obtained by utilizing the wafer curvature method of strain analysis.

ISSN:1071-1023    

DOI:10.1116/1.584172

出版商:American Vacuum Society    

年代:1988

数据来源: AIP