Naohiro Momma

A new multilevel interconnection system for submicrometer VLSI's using multilayered dielectrics of plasma Silicon Oxide and low-thermal-expansion polyimide

A new multilevel interconnection system for submicrometer VLSIs has been developed that utilizes multilayered dielectrics of inorganic and organic materials. This system was achieved by using the low-thermal-expansion polyimide PIQ-L100 underlying plasma CVD silicon oxide and doing an etch-back of overthick PIQ-L100. As the most important parameters of this system, the multilayered dielectric thickness and etch-back process of overthick PIQ-L100 were investigated.

Effects of Excited Plasma Species on Silicon Oxide Films Formed by Microwave Plasma CVD

By using a microwave plasma deposition system, effects of highly excited plasma species on the film formation of silicon oxide have been studied and the roles of excited ion and radical species have been investigated by emission spectra of the excited plasma species. A strong correlation was confirmed between film quality and the amount of highly excited ion species transported to the substrate. Furthermore, high quality films could be formed by increasing the amount of the excited species.

Effects of Applied Magnetic Fields on Silicon Oxide Films Formed by Microwave Plasma CVD

By using a microwave plasma deposition system in which distributions of applied magnetic fields can be varied, the effects of the ECR position and plasma species on deposition rate and deposited film quality of silicon oxide are studied. The following results are obtained: deposition rate increases when not only O2 but also SiH4 as a material gas are excited by ECR, and high-quality film equivalent to thermal SiO2 film can be formed when the ECR position is located close to the substrate. It is suggested that the process of forming high-quality film is related to highly excited ions transported to the substrate.

A practical model for growth kinetics of thermal SiO2 on silicon applicable to a wide range of oxide thickness

Abstract A simple and practical model which simulates the thermal growth of SiO2 on silicon is presented. Dry O2 oxidation is modeled assuming existence of a constant Si-SiO2 interface potential with an accompanying field retarding the transport of charged oxidants in the oxide near the interface. It is shown that HCl oxidation also can be simulated in the framework of this model. Further, the model is extended to treat the pyrogenic H2O oxidation in which both oxygen and water contribute as oxidants. The present model can be used to simulate the oxide growth kinetics for the above three types of oxidation, in a wide range of oxide thickness including very thin oxides below several hundred of A the region which is important in the fabrication of MOS VLSIs.

High-Quality, High-Rate SiO2 and SiN Films Formed by 400 kHz Bias Electron Cyclotron Resonance-Chemical Vapor Deposition

A new electron cyclotron resonance (ECR) plasma CVD system is proposed to form high-quality SiO2 and SiN films at high rates. The system applies 400 kHz voltages which ions can follow to the substrate. The system efficiently produces, without heating: 1) SiO2 films in which density and Si-O bond strength are equivalent to those of a thermally oxidized (about 1000° C) film for which deposition rate is higher than 1.2 µ m/min and 2) Si-H bond-free SiN films in which density and resistivity are higher than those of films formed by conventional plasma CVD systems and for which deposition rate is higher than 0.8 µ m/min.

A novel scaled-down oxygen-implanted polysilicon resistor for future static RAMs

A novel scaled down high resistor (1µm or less in length) for future static RAMs was realized by using the slow arsenic diffusion in oxygen implanted polysilicon, where arsenic is partially doped to form polysilicon interconnection layer. The current voltage characteristics of the oxygen doped polysilicon resistors were almost linear, and the marked decrease in resistance for higher applied voltage, observed in non-doped polysilicon, could not be found. Moreover the field effect modulation of the resistance in the oxygen doped polysilicon was much less than that of non-doped one. Applicability of the scaled down oxygen implanted polysilicon resistor was thus demonstrated for future static RAMs.

Mechanism of Hydrogen Adsorption and Hydrogen-Deuterium Equilibration on Copper Surface

Behavior of hydrogen and deuterium on copper surface was studied in detail. Desorption spectra, adsorption isotherms and the kinetics of exchange reaction predicted that hydrogen is adsorbed dissociatively and the H2–D2 equilibration proceeds via the recombination between adsorbed atoms. The optimum values of rate constants for adsorption and desorption were determined by simulating the reaction time course. Obtained constants were found to coincide with those derived by the transition state theory. Influence of molecular motion on adsorption was examined by analyzing the computed trajectories of hydrogen on a dual Cu site.