Showing papers on "Nitride published in 1982"

Advantages of thermal nitride and nitroxide gate films in VLSI process

Abstract: Thin gate SiO 2 films thinner than 200 A often deteriorate throughout developmental VLSI processes, including refractory metal or silicide gates and ion- or plasma-assisted processes. Thermal nitridation of such SiO 2 films improves the MOS characteristics by producing surface protective layers against impurity penetration and by producing good interfacial characteristics. This fact indicates that a thermally grown silicon nitride film on a silicon substrate is the most promising candidate for a very-thin gate insulator. Experimental data show significant benefits from the nitride film for future VLSI devices.

Hydrogen plasma etching of semiconductors and their oxides

Abstract: Hydrogen plasmas have been used to etch surfaces of semiconducting materials (e.g., GaAs, GaSb, InP, Si), their oxides, and Si nitride. Using a combination of analytical techniques—spectroscopic ellipsometry, Auger spectroscopy, and scanning electron microscopy (SEM), the etch rates, the surface composition and morphology have been studied. It is demonstrated that the selective etching rate of hydrogen plasma for Si over SiO2 is ∠30, and that for GaAs oxide over GaAs is ∠2. It is also shown that the hydrogen plasma etched (and air exposed) GaAs surfaces have a Ga/As concentration ratio nearly equal to that of the air cleaved GaAs surface. Similar results have also been obtained for GaSb. Hydrogen plasma etched InP shows surface segregation and is rich in In. The etch rates of the semiconductors and their oxides vary by several orders of magnitude from compound to compound as determined from ellipsometry and SEM. It is also demonstrated that scanning ellipsometry can be used to monitor surface etching proc...

Processes for manufacturing insulated-gate semiconductor devices with integral shorts

Abstract: Process for manufacturing insulated-gate semiconductor devices such as MOSFETs being with a semiconductor wafer (such as silicon) including a drain region, a gate insulating layer initially formed uniformly on the surface of the drain region, and a polysilicon conductive gate layer. A two-stage polysilicon etch procedure is disclosed. The initial etch produces relatively narrow channels with substantially vertical sidewalls. Unetched portions of the polysilicon layer are used as masks during a first P type diffusion to form a shorting extension of the device base region and during the forming of a silicon nitride mask layer by a highly directional process, such as ion implantation, which avoids the formation of any nitride layer on the channel sidewalls. In a subsequent lateral etch step, previously unetched portions of the polysilicon gate electrode layer are etched to define insulated polysilicon gate electrode structures. These structures extend upwardly from and are spaced along the principal surface, and are also spaced from the silicon nitride masks. Then, the silicon nitride masks are each used as a combination diffusion and selective oxidation mask to form MOSFET source and base regions and to oxidize the polysilicon gate electrode sidewalls. The silicon nitride mask is removed, and appropriate electrode metallization applied.

Interfacial reactions between aluminum and transition‐metal nitride and carbide films

Abstract: Recently transition‐metal nitrides and carbides have received great interest as diffusion barrier materials in contact structures for silicon semiconductor devices. Excellent stability of the contact structure is achievable through heat treatments of up to 600 °C when Ni is used as the top metal layer. However, the same transition‐metal compounds show poor barrier properties with Al as the top layer if heat treated to 600 °C. We have therefore investigated the failure mechanism of transition‐metal nitride and carbide barrier materials in Al overlayer metallizations. This knowledge has enabled us to develop high‐temperature contact structures for silicon semiconductor devices by using an intermetallic compound of Al instead of plain Al for the top layer.

A Proposed Hydrogenation/Nitridization Passivation Mechanism for GaAs and Other III–V Semiconductor Devices, Including InGaAs Long Wavelength Photodetectors

Abstract: A surface passivation method for , with possible extensions to and , is proposed. For , a correlation between recent device work (on solar cells, field effect transistors, MOS devices, and photodiodes) and the experimental Ga‐As‐O phase diagram provides strong evidence of the role of elemental surface or interface arsenic or arsenic oxide in device performance degradation. On this basis, a hydrogenation/nitridization passivation technique is proposed. The reactions to remove surface As and are The surfaces may be plasma coated in the same chamber with a wide bandgap nitride (e.g., ) for passivation and to tie up any elemental Ga. The hydrogenation and nitridization steps may be simultaneous if an ammonia plasma is used. A final layer for long‐term surface protection is recommended. Recent experimental data on surface treatments support this passivation mechanism. The extension to (for long wavelength optical detectors) is by thermochemical calculations supported by recent parallel measurements of the In‐Ga‐As‐O phase diagram. Note the conductive indium oxide must also be removed, as by the reaction

New fabrication process for Josephson tunnel junctions with (niobium nitride, niobium) double‐layered electrodes

Abstract: All hard Josephson tunnel junctions, whose base and counter electrodes are composed of double‐layered niobium nitride (NbN) and niobium (Nb) films, have been successfully fabricated by isolating a junction sandwich formed on a whole silicon wafer with a reactive ion etching technique. The reactive ion etching technique has been used for patterning both base and counterelectrodes, and self‐aligning definition of junction areas has been performed. The fabricated junctions show good quality single‐particle tunneling characteristics and excellent uniformity in critical currents.

Characterization of low‐pressure chemical‐vapor‐deposited and thermally‐grown silicon nitride films

Abstract: Low‐pressure chemical vapor‐deposited (LPCVD) silicon nitride films on silicon have been characterized by means of Rutherford backscattering (RBS), Auger electron spectroscopy (AES) combined with ion sputtering, and spectroscopic ellipsometry. It appeared that all LPCVD samples in the examined thickness range of 50 –500 A had an oxygen‐containing layer equivalent to 15–20 A of SiO2 at the nitride‐silicon interface. This interfacial layer originates from the native silicon oxide present at the silicon substrate when the deposition of nitride is started. For comparison, oxide‐free silicon substrates were nitrided in ammonia at temperatures between 800–1160 °C. The thermal nitride films were found to be very thin, at the most 30 A, even after 5 h of nitridation. Both the LPCVD and thermal nitride films oxidize slightly when transferred into the ambient; a surface layer equivalent to 8 A of SiO2 was detected. Auger and RBS results agree very well for all nitride films investigated. It is shown that RBS can be...

Basal orientation aluminum nitride grown at low temperature by rf diode sputtering

Abstract: Aluminum nitride films with solely a (0001), or basal crystallographic orientation have been grown on single‐crystal silicon and silicon dioxide‐coated silicon at substrate temperatures below 100 °C. The deposition technique used was rf diode sputtering of an aluminum target in argon/nitrogen gas mixtures containing 50–100% nitrogen. Unintentional oxygen doping of the growing films was minimized by a target clean‐up procedure which was monitored by glow discharge mass spectrometry. X‐ray diffraction measurements on the films included relative integrated intensity, peak half width, and precise peak position from which the lattice constant normal to the basal plane was calculated. The preliminary results of a study of the evolution of film crystallography from multiorientation aluminum to single‐orientation aluminum nitride as the sputtering gas nitrogen content is increased are also presented.

Strengthening of a Sintered Silicon Nitride by a Post-Fabrication Heat Treatment

Abstract: The strength improvement of an injection-molded and sintered silicon nitride ceramic (15.5 wt% Y/sub 2/O/sub 3/+ 10.1 wt% produced by an oxidation heat treatment at 1500/degree/C is reported. The ceramic retains its strength after prolonged intermediate temperature exposure in air, whereas the untreated material suffers various degrees of cracking. 6 refs.

Sintered body of ceramics and preparation thereof

Abstract: There are disclosed a sintered body of ceramics, comprising 0.1 to 10% by weight of yttrium oxide; 0.1 to 10% by weight of aluminum oxide; 0.1 to 10% by weight of aluminum nitride; 0.1 to 5% by weight of at least one silicide selected from the group consisting of magnesium silicide, calcium silicide, titanium silicide, vanadium silicide, chromium silicide, manganese silicide, zirconium silicide, niobium silicide, molybdenum silicide, tantalum silicide and tungsten silicide; and the balance being silicon nitride, and a process for producing a sintered body of ceramics, which comprises molding a powder mixture of the same composition, and sintering the resultant molded compact in a non-oxidative atmosphere. According to the present invention, it is possible to manufacture sintered body having high density and excellent impact resistance.

Process for manufacturing integrated bi-polar transistors of very small dimensions

Abstract: A process is provided for manufacturing bi-polar transistors integrated on silicon. To form transistors of very small dimensions, a layer of polycrystalline silicon is deposited (after a localized oxidization step) which is etched and which is doped so as to serve as doping source for P+ extrinsic base regions of the transistor. After doping of the P intrinsic base, the oxide and/or nitride is then deposited at low pressure which is implanted with an impurity facilitating dissolution thereof. On the vertical walls of the polycrystalline silicon around the base, the nitride is not dissolved. Elsewhere it is easily dissolved. Advantage is taken of the oxide or nitride thickness which remains to form by diffusion of an N+ emitter region which will not extend laterally as far as the P+ type extrinsic base but which will allow to remain an intrinsic base of very small thickness. The emitter diffusion may take place through a second polycrystalline silicon layer.

Preparation of silicon carbide–silicon nitride fibers by the controlled pyrolysis of polycarbosilazane precursors

Abstract: The development of silicon carbide-silicon nitride fibers (SiC-Si3N4) by the pyrolysis of polycarbosilazane precursors is reviewed. Precursor resin, which was prepared by heating tris(N-methylamino)methylsilane or tris(N-methylamino)phenylsilane to about 520 C, was drawn into fibers from the melt and then made unmeltable by humidity conditioning at 100 C and 95 percent relative humidity. The humidity treated precursor fibers were pyrolyzed to ceramic fibers with good mechanical properties and electrical resistivity. For example, SiC-Si3N4 fibers derived from tris(N-methylamino)methylsilane had a tensile rupture modulus of 29 million psi and electrical resistivity of 6.9 x ten to the 8th power omega-cm, which is ten to the twelfth power times greater than that obtained for graphite fibers.

Formation of Cubic Boron Nitride from Rhombohedral Boron Nitride by Explosive Shock Compression

Abstract: When rhombohedral BN, which has a layer structure with a three-layered stacking sequence, was shock-compressed at 40, 60, and 100 GPa, it was converted to cubic BN. Hexagonal BN was converted to wurtzite-type BN under the same conditions. These results indicate that the transformation proceeds by a diffusionless mechanism in which the stacking sequence of the BN layers in the starting materials is retained during the process.

Chemical vapor deposition and characterization of phosphorus nitride (P3N5) gate insulators for InP metal‐insulator‐semiconductor devices

Abstract: A new gate insulating film consisting of P3N5 was formed on an InP surface by a new chemical vapor deposition (CVD) technique. A suitable combination of reagents (PH3 and NH3) made P3N5 CVD feasible in an ambient free from oxygen and having excess phosphorus pressure. The new insulator revealed ohmic conduction with a resistivity as high as 104Ω cm. The breakdown field intensity increased up to 107V/cm at room temperature. The low frequency dielectric constant was 3.7 e0. A very minor hysteresis was seen in the capacitance‐voltage curves measured on P3N5‐ InP metal‐insulator‐semiconductor diode. The interface state density was reduced to 1012/cm2eV at an energy near the conduction band edge. Photoluminescence spectra were measured before and after CVD to determine the surface passivation effect.

Sintered bodies of aluminum nitride

Abstract: Sintered bodies of aluminum nitride There is disclosed a sintered body of aluminum nitride comprising a sintered body of powder mixture containing (a) A?N powder : 100 parts by weight, (b) at least one compound selected from CaO, BaO, SrO and a compound capable of being converted into one of these oxides by sintering : 0.05 to 6 parts by weight, and (c) carbon powder or powder of a compound capable of being converted into carbon by sintering : more than 0 to not more than 7 parts by weight. The sintered bodies of aluminum nitride according to this invention have high density and excellent properties such as high thermal conductivity.

Iron nitride and carbonitride phases in a nitrogen implanted carbon steel

Abstract: Iron nitride and carbonitride phases formed during nitrogen implantation and subsequent thermal annealing of a medium‐carbon steel are investigated by means of conversion electron Mossbauer scattering. The results are compared to previous work on similar systems and also discussed in terms of the mechanical properties of ion implanted steels.

Sealed-interface local oxidation technology

Abstract: A new regime of local oxidation, dubbed SILO for Sealed-Interface Local Oxidation, is explored. In SILO processing, a film of silicon nitride is in intimate contact with the silicon surface. The ubiquitous native oxide is effectively eliminated by using nitrogen ion implantation into silicon or plasma-enhanced nitridation to form a "sealing film" of approximately 100 A in thickness. The oxidation rate of both types of films is characterized and found to be nearly equivalent. A 100-A film can mask the growth 0f 7000 A of oxide in wet oxygen at 950° C. With a sealed interface it is found that the usual "bird's beak" formation is completely suppressed in local oxidation. An approximate theoretical analysis shows that even a very thin interfacial oxide, acting as a lateral diffusion path for the oxidant species, can lead to a significant bird's beak. With a sealed interface using a 90-A film, the thick-oxide to bare-silicon transition region is chisel shaped, with approximately 45° slopes. The transition region is even more abrupt if a conventional LPCVD nitride film is deposited on the sealing film before patterning. However, for total nitride thicknesses greater than about 300 A, defects are generated along the pattern edges aligned in [110] directions. Crystal damage generated during oxidation is found to be due to the intrinsic stress in the LPCVD nitride film. Argon-ion implantation into LPCVD nitride is found to be effective in reducing the defect density. A defect-free abrupt profile is produced by combining SILO with a nitride-oxide sandwich.

Effects of various additives on sintering of aluminum nitride

Abstract: Effects of thirty additives on sintering A/N were investigated. The addition of alkali earth oxides and rare earth oxides gave fully densified aluminum nitride. This is due to the formation of nitrogen-containing aluminate liquid in the system aluminum nitride-alkali earth oxides or rare earth oxides. Microstructural studies of the sintered specimens with the above two types of additives suggested that the densification was due to the liquid phase sintering. Additions of silicon compounds resulted in poor densification by the formation of highly refractory compounds such as A/N polytypes.

Carrier conduction and trapping in metal‐nitride‐oxide‐semiconductor structures

Abstract: Carrier conduction and trapping in metal‐nitride‐oxide‐semiconductor structures are investigated. It is clearly shown that holes dominate the carrier conduction in the nitride for both gate polarities, and electrons injected into the nitride from a cathode are almost completely annihilated by recombination in the nitride with holes injected from an anode, which is revealed by an induced junction technique. A model that the memory traps in the nitride act as the recombination centers in steady‐state conditions is proposed. The recombination distance, the capture cross section, and the density of the memory traps or the recombination centers are estimated to be 81 A, 2.86×10−13 cm2, and 4.32×1018/cm3, respectively, by fitting the experimental results with the theory based on the proposed model.

Manufacture of semiconductor device

Abstract: PURPOSE:To improve the uniformity of the thickness of a film and pattern dependence by grinding the rear surface of a semiconductor substrate, and forming the films under the state wherein the insulating film on the rear surface is removed, when a silicon nitride film, a silicon oxide film and the mixed films of those films as passivation films are formed. CONSTITUTION:A rear surface is ground before a plasma nitride film is formed. At this time, a temporary passivation film is formed because a semiconductor element might be contaminated. As one method, a film which is about 1/5-1/3 the specified plasma film is formed, and then the rear surface is ground. As the second method, a polyimide film is once attached, then the rear surface is ground and the polyimide film is removed after the grinding. The excellent results can be obtained by both methods. This is because the rear surface by a semiconductor substrate is completely at the same potential as that of a lower electrode. Therefore, high frequency power 3 which is applied through an upper electrode 2 generates plasma discharge effectively, and a silicon nitride film is formed on the semiconductor substrate 1. Thus, pattern dependence and the nonuniformity of the film thickness can be improved.

Fabrication of isolation oxidation for MOS circuit

Abstract: A method is disclosed for fabricating an isolation oxidation (44), also referred to as field oxide, to separate the active regions on the surface of an MOS integrated circuit. On the surface of a semiconductor substrate (24) there are fabricated in successive layers an oxide layer (26), a polysilicon layer (28) and a nitride layer (30). A patterned resist layer (32) is formed on the surface of the nitride layer (30). The nitride layer (30) is etched through an opening (34) in the resist layer (32), which is then removed. The isolation oxidation (44) is then grown through an opening (36) in the nitride layer (30). The isolation oxidation (44) comprises oxide derived from the oxide layer (26) and from oxide produced from the polysilicon layer (28) and the semiconductor substrate (24). Next, the nitride layer (30), the polysilicon layer (28) and the oxide layer (26) are etched. The resulting isolation oxidation (44) has a bird's-beak area (46) which is less than 50% of the width of a bird'-beak area (14) produced using conventional MOS manufacturing processes.

Room Temperature Formation of Si‐Nitride Films by Low Energy Nitrogen Ion Implantation into Silicon

Abstract: The direct nitridation of silicon could be performed for the first time at room temperature by low energy nitrogen ion implantation up to the saturation concentration. Nearly stoichiometric Si‐nitride layers with thicknesses from 1 to 9 nm were obtained for nitrogen ion energies in the range 500 eV–5 keV. The chemical composition and the electronic states as a function of depth were analyzed by a combination of Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS) with argon ion sputtering. Concentration depth profiles for different nitrogen ion energies and implantation times are presented.

Shrinkage and growth of oxidation stacking faults during thermal nitridation of silicon and oxidized silicon

Abstract: We have studied the shrinkage and growth of preexisting oxidation‐induced stacking faults during thermal nitridation of silicon without oxide film and of oxidized silicon with oxide film 23 to 5600 A thick. Nitridation was carried out at 1050 to 1200 °C under ammonia partial pressures of 10−3 to 4 kg/cm2. We observed that stacking faults in silicon without oxide film shrink linearly with nitridation time and their shrinkage rate increased as the partial pressure of ammonia increased. On the other hand, stacking faults in oxidized silicon with oxide film grew during nitridation and their growth rate increased with the increase of ammonia partial pressure after the pressure reached about 10−1 kg/cm2 and with the increase of the thickness of the oxide film. Based on these results, we have proposed a model which assumes that in the shrinkage phenomenon, an undersaturation of silicon self‐interstitials occurs near the silicon surface because of silicon‐cation migration from the silicon‐nitride interface to the nitride surface. The model also assumes that the growth phenomenon occurs because of the supersaturation of silicon self‐interstitials, which are generated by the reaction of ammonia with silicon dioxide and are injected into the bulk of silicon through the silicon‐nitride interface. The projected results of this model agree reasonably well with the experimental results.

Growth Kinetics of Silicon Thermal Nitridation

Abstract: An analytic model for the growth kinetics of silicon thermal nitridation has been developed, in which the nitrogen radicals diffused across the as-grown thermal silicon nitride layer have been characterized by a characteristic diffusion length. It has been shown that the direct thermal nitridation of silicon in ammonia gas or nitrogen gas is similar to the silicon oxidation in oxygen or steam when the characteristic diffusion length of the nitrogen radicals is much larger than the as-grown silicon nitride layer. However, when the thickness of the as-grown silicon nitride film is larger than the characteristic diffusion length of the nitrogen radicals, the thickness of the as-grown silicon nitride film tends to saturate. The self-limiting growth has been verified to be the "logarithmic" relation of the developed model, and the activation energy of the quasi-saturation thickness has been shown to be the activation energy of the characteristic diffusion length. Based on comparisons between the experimental data and the developed model the characteristic diffusion length has been shown to be very short and has been estimated to be smaller than I0~ for nitridation temperature below 1200~ and its activation energy has been estimated to be of 0.181 eV. Moreover, the linear growth rate constant and the parabolic growth rate constant of the as-grown thermal nitride films have been estimated to be of 1.286 and 1.546 eV, respectively, which are smaller than those of the silicon oxidation in dry oxygen or steam ambient. In addition, it has been shown that the linear growth rate constant of the thermal nitridation using ammonia gas is larger than that of the thermal oxidation using dry oxygen or steam ambient, which predicts that the surface-limited reaction of the silicon surface in ammonia gas is faster than that in dry oxygen or steam ambient. Silicon nitride films, which exhibit high structure density, high dielectric constant, good electrical properties, and strong inertness toward chemicals, have been widely used in semiconductor devices and integrated circuit fabrications. However, high quality silicon nitride films have been prepared by expensive methods such as chemical vapor deposition (CVD) or plasma deposition. In modern silicon technologies, * Electrochemical Society Active Member.

Synthesis of Silicon Nitride Powder from Silica Reduction

Abstract: Silicon nitride powder synthesis was investigated via the silica reduction method. Adding Si3N4 to the SiO2-C mixture increased the reaction rate and promoted the formation of homogeneous Si3N4 grains. This effect could be explained on the basis that each Si3N4 particle acts as a ‘seed’ for the reaction.

Sialon tool materials

Abstract: Sialons are phases in the Si–Al–Q–N and related systems that are built up of (Si, Al)(O, N)4 tetrahedra in the same way that the structural unit in the silicates is the (Si, Al)O4 tetrahedron. These new materials include nitrogen-containing ceramics, glasses, and glass-ceramics but only β’-sialon, the silicon-aluminium oxynitride isostructural with β-silicon nitride, Si3N4, has so far been commercially developed for engineering applications. Fully dense shapes are fabricated by pressureless sintering with additions of yttrium oxide to give the strongest ceramic yet known and the product holds great promise as a cutting tool for machining metals. Because of its high hardness, impact strength, and fracture toughness yttrium-sialon tool tips are superior to cobalt-bonded tungsten carbide (hardmetal) for many cutting applications.

Empirical study of the metal‐nitride‐oxide‐semiconductor device characteristics deduced from a microscopic model of memory traps

Abstract: A graded‐nitride gate dielectric metal‐nitride‐oxide‐semiconductor (MNOS) memory transistor exhibiting superior device characteristics is presented and analyzed based on a qualitative microscopic model of the memory traps The model is further reviewed to interpret some generic properties of the MNOS memory transistors including memory window, erase‐write speed, and the retention‐endurance characteristic features

Thin-film transistors on a-Si:H

Abstract: A comparison has been made of the characteristics of nitride and oxide MOSFET's fabricated with thin films of amorphous silicon. Published data indicate that Si 3 N 4 -Si:H thin film devices are superior to the oxide devices. Accumulation-mode MOSFET's were fabricated in which the drain current arises from electric-field induced accumulation of electrons (majority carriers) at the a-Si:H-insulator interface. Hydrogenated amorphous silicon layers were deposited at 230°C by glow-discharge plasma decomposition in silane. The deposition conditions were found to be critical, and in the present study the films were grown on an electrically grounded substrate with RF power of 1 W applied to the counter electrode. The a-Si:H was deposited onto silicon nitride and silicon dioxide layers of 100-500-nm thickness, and thin-film transistors were fabricated with the inverted MOS configuration. Devices were tested with on/off drain current ratios greater than 104for a gate voltage swing of 0 to 12 V and drain-current saturation for source-drain voltages of less than 12 V. The properties of MOSFET's on a-Si:H are discussed with a comparison of the silicon-nitride-a-Si: H and silicon-dioxide-a-Si:H interfaces and an evaluation of doped active layers. The transistors on silicon dioxide are as good as any reported to date on silicon nitride.