Lewis E. Terry

Metallization systems for silicon integrated circuits

An investigation into single and composite layered metallization systems is described with respect to their limitations, possible failure mechanisms, and problems encountered in fabrication. Systems investigated include metals such as chromium, titanium, tungsten, and molybdenum in conjunction with gold. Comparisons are made to conventional aluminum with respect to ohmic contact to silicon, metallurgical reactions, behavior in adverse environmental conditions, method of deposition, and processing difficulties.

Composition profiles and Schottky barrier heights of silicides formed in NiPt alloy films

Metal silicides such as PtSi and NiSi have important applications in silicon integrated circuit technology as rectifying or Ohmic contacts. With a view to obtaining contacts with Schottky barrier heights adjustable between those of NiSi and PtSi, silicides were formed in NiPt alloy films with varying concentrations of Ni and Pt. The metal films were sputter deposited sequentially from Ni and Pt targets and also from a single alloy target containing 15 wt% Pt. Silicides were formed by sintering at 475 °C for 20 min. The depth‐compositional profiles of these films were obtained by Auger electron spectroscopy (AES) coupled with Ar+ ion sputtering. The effects of the sintering and the presence of oxygen impurity on the composition profiles are discussed. The chemical effects observed in the Auger spectra from the silicides are presented. The Schottky barrier height (φB) of the silicide film on n‐type silicon increases from that of NiSi‐nSi to PtSi‐nSi with increasing amount of Pt in the NiPt films. The variat...

Application of high‐rate E×B or magnetron sputtering in the metallization of semiconductor devices

High‐rate sputtering has been investigated as a useful method of depositing aluminum and aluminum‐alloy metallization on semiconductor devices. Although the deposition rate is not as high as typical electron‐beam systems, it is still competititve and the added ease of controlling film uniformity and composition by sputtering power and target selection make it very attractive. Furthermore, in contrast to conventional diode sputtering, the radiation bombardment of the substrate by the plasma is reduced significantly which results in a minimum of self‐induced heating and charges in dielectric layers. Although this low temperature may not be conducive to ideal conductor step coverage, the ease of, and relatively low temperature for, annealing the radiation damage shows it can be a viable method for conductor metallization of bipolar and MOS devices.

Schottky barrier heights of nickel‐platinum silicide contacts on n‐type Si

The barrier heights of NiPt silicide–n‐type Si have been determined from the saturation current density of diodes for various concentrations of Ni and Pt. Ni‐Pt films on Si were heated to 475 °C to obtain a NiPt silicide. The barrier height varies smoothly from that of NiSi‐Si to PtSi‐Si with increasing amounts of Pt in the NiPt films. For 19 wt% Pt the barrier is 0.69 eV and for 67 wt% Pt the height is 0.78 eV.

Auger spectroscopy analysis of palladium silicide films

The formation of Pd2Si in Pd films sputter deposited on Si substrates and heated up to 400 °C has been studied by measuring the depth profile using Auger electron spectroscopy (AES) and Ar+ ion sputtering. Significant chemical effects in the silicon LVV Auger peak shape have been observed, enabling the easy differentiation of the silicide from elemental silicon. The depth profile indicated that the silicide phase is formed at the Pd/Si interface even in the unannealed films. In forming the silicide, the silicon atoms diffuse through the film and on arrival at the surface oxidize to form a thin layer of SiO2. Some of the problems encountered in the determination of the depth scale from the AES data are pointed out.

Industry trends in power integrated circuits

The authors consider some of the recent trends in power integrated circuits. They discuss the novel processes and device configurations which the semiconductor industry is developing to meet the needs of customers. Also included is a qualitative look at the design tradeoffs which influence the choice of technology for a particular application. The movement toward high-performance and higher-density circuitry, which demands smaller geometries and sophisticated processing, is also discussed. Particular attention is given to smart power (smart discrete devices and integrated circuits), multiple-output technology, high-voltage junction isolation, and high-voltage dielectric isolation.<<ETX>>

Smartdiscretes, new products for automotive applications

Device structures and characteristics for three Smartdiscretes which have automotive applications are presented. Smartdiscretes are discrete power devices which incorporate a few small signal devices on a chip without added process complexity. The first is a power MOSFET with very low on-resistance and an integral temperature sensor. The second is an ignition coil driver with a temperature-compensated clamp. The third is a device with a built-in current limit, electrostatic discharge (ESD) protection, and a temperature-compensated clamp that is suitable for driving small inductive loads such as injector drivers.<<ETX>>

Metallization Systems for Integrated Circuits

Metallization systems materials for IC, discussing environmental stability, metals electromigration, electrochemical corrosion tests, etc

Abstract: AES study of the silicide formation in 85%Ni–15%Pt alloy films

Metal silicides such as NiSi and PtSi have important applications in integrated circuit technology, particularly in the fabrication of Schottky barrier diodes with reproducible barrier heights. The barrier heights of PtSi–nSi and NiSi–nSi are 0.85 and 0.65 eV, respectively. With a view to obtaining a barrier height in between those of PtSi and NiSi, Ni–Pt alloy films were sputter deposited on n‐type silicon from a single‐alloy target of composition 85wt %Ni–15wt% Pt and sintered at 475 °C for 20 min to form a silicide. The surface composition and the depth‐compositional profile were determined by Auger electron spectroscopy (AES) coupled with Ar+ ion sputtering. The characteristic Auger spectra from PtSi and NiSi showed significant chemical effects. The LVV Auger spectrum from silicon in PtSi revealed pronounced line‐shape changes from that characteristic of elemental silicon. In the case of NiSi, however, no pronounced line‐shape changes in the Si LVV Auger spectrum could be observed, while strong charac...