A self-aligned polycide gate interconnect process has been developed at STL in order to reduce the RC delays in existing and planned MOS circuits. This process has been chosen due to its ease of implementation into an existing process line. Incoherent lamp annealing is used to form the silicide after the deposition of titanium over patterned polysilicon.

This paper will discuss the various materials and processes considered, outlining the significant attributes of each. The factors which must be controlled to achieve a practical process are discussed, together with the degree of redistribution of dopants and the role of other impurities.

Transient processing of titanium silicides on single-crystal Si in a non-isothermal reactor provides high quality films. Heat from quartz-hal?gen tungsten lamps and a small temperature gradient act as driving forces for the reaction. The temperature gradient, small compared to the concentration gradient, shows negligible influence on the formation process. The influence of sample reflectivity on the other hand is appreciable. From Xe+ marker experiments, Si atoms are found to be the moving species either up or down the temperature gradient. Small amount of TiSi as an intermediate phase is found to be coexistent with TiSi2. The silicide formation of the implanted wafers is somewhat slower than that of the unimplanted wafers.

Silicidation of titanium on silicon is carried out with the halogen lamp annealing. It is found that the lamp annealing is quite effective in forming an oxide-free and homogeneous titanium disilicide layer with resistivity of 15–17 μohm·cm. Rutherford backscatterring and X-ray diffraction studies show that the halogen lamp annealing over 650 °C for only 60 sec results in disilicide. By a silicidation reaction, arsenic and boron atoms at silicon beneath a titanium layer are incorporated into a formed silicide layer. Arsenic atoms initially in a titanium layer are swept toward the surface as silicidation reaction proceeds. Arsenic atoms in titanium have an effect to retard silicidation reaction.

Changes in the luminescence spectra of InP caused by Si+ implantation and subsequent rapid lamp annealing were studied. It was found that the best activation of dopants was obtained in the case of hot implantation and lamp annealing in regimes close to melting of InP.

A rapid thermal process for the diffusion of Zn into GaAs has been developed to fulfill the need for highly doped p type layers in GaAs technology. The process uses a solid Zn:Si:O source layer and a quartz-halogen lamp system for the thermal drive-in. Surface concentrations of the order of 1020/cm3 have been achieved with good depth reproducibility and low lateral diffusion. Specific contact resistance of Au:Zn/Au alloyed contacts fabricated using this process was in the 10−7 ohm-cm2 range.

Undoped SI (100) GaAs has been implanted with selenium and tin ions at room temperature at an ion energy of 300 keV and using ion dose in the range 1 × 1014 to 1 × 1015 ions cm−2. Transient annealing at 1000°C and above has been studied using electrical measurements and transmission electron microscopy. The results show that tin implanted samples have comparatively higher values of electrical activity and mobility than those implanted with selenium ions. A difference in the microstructure of these two implants was observed. Selenium implanted samples show dislocation lines and loops possessing 1/2<110> Burgers vectors while tin implanted GaAs contains dislocation loops of 1/2<110> and 1/3<111> types and also dislocation lines having 1/2<110> Burgers vectors. Both types of defect in tin implanted samples are decorated with precipitates.

The conventional method for fabricating silicon IMPATT diode structures involves the epitaxial growth of successive n- and p-type layers onto a n+ substrate followed by a boron diffusion to form the final p+ layer. The high temperature time cycles experienced by the structure during these processes cause junction interfaces to become degraded through dopant diffusion. In this paper we examine the application of laser processing techniques to the epitaxial regrowth of low temperature deposited layers and report on the nature of the recrystallised material.

Capped and capless incoherent light annealing of high and low dose silicon implants into GaAs have been compared with conventional capless furnace annealing of the same implants. The yield and uniformity of DC characteristics of selectively implanted depletion mode MESFET's fabricated on 2-inch wafers annealed by the above three methods have also been compared. Capped incoherent light annealing was found to give results comparable to and in some cases better than conventional furnace annealing both in terms of activation of the implants and also device performance.

Optimization and the advantages of rapid thermal annealing (RTA) for the electrical activation of deep 300 keV Si+ implants into GaAs are investigated and established for doses of 6 to 8×1012 cm−2. These implant conditions are appropriate for power FETs. Results are compared with those based on conventional controlled atmosphere capless furnace annealing (CAT).

The RTA yielded higher peak electron concentrations, high mobilities and greater uniformities in the gateless FET saturation currents. The deep implant results ontrast with those for shallower implants for low noise FETs. These differences are explained using a well-known implant damage model.

Silicon dioxide films have beep deposited at an oxygen pressure and substrate temperature as low as 10−2 Pa and 300°C, respectively, using a partially ionized nozzle-beam technique. The refractive index of the film is equal to that of the thermally grown silicon dioxide film, but a frequency shift was obsrved in the infrared absorption peak at 1045 cm as compared to 1080 cm−1 of the thermally grown silicon dioxide film. This frequency shift disappeared after the deposited film was annealed in a rapid thermal annealing system utilizing an incoherent light source. We emphasize that from the standpoint of device fabrication, although the annealing temperature is high (%1100°C), the time is very short (seconds), so that this process is still compatible to the requirementsof low temperature processing. Effects of rapid thermal annealing on LPCVD and PECVD oxides are also studied and the results are compared to that of the oxide deposited by the partially ionized nozzle-beam technique.

One of the applications of high dose ion implantation is to form surface alloys or compound layers. The detailed characterization of such composite structures is of great importance. This paper tries to answer the question: how can we outline, at least, a qualitative picture from the optical properties measured by ellipsometry of high dose Al and Sb implanted silicon. Attempts are done to separate the effect of implanted impurities from the dominant disorder contribution to the measured optical properties. As the ellipsometry does not provide information enough to decide the applicability of optical models therefore methods sensitive to the structure (channeling and TEM) were applied too.

The extent of boron channeled into interstitial and substitutional sites is measured for singly charged ions of B, BF, BCl, and BF2 implanted into <100> silicon. We find that the most deeply penetrating boron atoms ome to rest in interstiitial sites with the consequence that electrical junctions are always more shallow than etallurgical junctions. This result is essentially independent of ion mass, energy, and fluence.

Ion-Projection Lithography (IPL) is a future production technique for submicron electronic devices, wich combines the advantages of e-beam and X-ray lithography without having their disadvantages. Like electrons, ions can be accelerated, focused and deflected, and as is the case with X-rays, scattering in resist layers is less pronounced as for e-beams. Experimental results of IPL obtained with an Ion-Projection-Lithography-Machine IPLM-01 are presented: Ion images of self supporting masks ten times demagnified with a geometrical resolution < 0.25 μm printed into organic and inorganic resist layers in high volume production oriented times.

We have shown that irradiation of Ag-Si and Au-Si interfaces by 14 MeV 016 ions can produce non-registered silicon at the metal-silicon interface. Evidence that this effect is due to electronic energy loss of the bombarding ion is presented. The possible relationship of this effect to MeV-ion enhanced adhesion is discussed.

We report on our studies of Ni transport induced by 300 keV Xe irradiation of 25 nm Ni films evaporated on thermally grown SiO2 at Xe fluences of 1013-1016 cm-2 and at temperatures of 300-750 K during irradiation. Cross-sectional TEM, and selective etching combined with 2 MeV He backscattering spectrometry and ESCA were used to profile the Xe and Ni within the SiO2. At 300 K, backscattering shows cascade mixing dominates, although only ~ 1/35 that predicted by cascade theory, with most of the Ni in the SiO2 contained in a resolution limited peak adjacent to the SiO2 interface. TEM shows that this Ni is contained in a 5 nm band, 5 nm below the interface as Ni oxide clusters. Examination of the satellite structure of the Ni 2p line by XPS also shows this band is predominantly Ni2+. At 750 K, the near-surface peak vanishes and only recoil implantation is evident. Ni0 is evident by XPS in samples irradiated at 300 K, though not at higher temperatures. We explain our results in terms of phase separation during cooling of the collision cascade.

Thin layers (~1,000 A ) of Ni and Co have been reacted with both (100) and amorphous silicon (a-Si) using a pulsed ion beam. Samples were analyzed using Rutherford backscattering, x-ray diffraction, and transmission electron microscopy. Rutherford backscattering showed that the metal/a-Si and metal/(100)-Si reaction rates were comparable. Both reactions began at the composition of the lowest eutectic. For comparison. furnace annealing of the same structures showed that the reaction rate of Ni with amorphous silicon was greater than with (100) Si; Co reacted nearly identically with both substrates. Diffraction data suggest that pulsed ion beam annealing crystallizes the amorphous silicon before the metal/a-Si reaction begins.

An attempt has been made to systematically sort out the characteristic modes of morphological transition in the energy beam recrystallized thin film silicon on insulating substrates, and to relate them to the mechanisms of solid-liquid interface stability breakdown. Stable to unstable breakdown modes include faceted, cellular, and dendritic configurations as well as transient and composite configurations thereof. These primary modes of breakdown then lead to the secondary modes of breakdown which constitute the sub-boundary formation. The mechanics of the primary (interface) breakdown and that of the secondary (sub-boundary) breakdown must be clearly differentiated in understanding the breakdown process. Constitutional supercooling and absolute supercooling models have been used to explain the various interface instabilities.

Subboundaries are the major crystalline defects in thin semiconductor films produced by zone-melting recrystallization (ZMR). Using transmission electron microscopy (TEM) and chemical etching we have analyzed the angular discontinuity and defect structure of subboundaries in ZMR Si films. Annealing in oxygen has resulted in the elimination of dislocation bands from sizable regions of some films. Calculations suggest that cellular growth due to constitutional supercooling may not occur in some Si ZMR.

We review recent results of our Graphite Strip Heater Si-on-Insulator (SOI) effort: (i) recrystallization of SOI films on 100 mm wafers, (ii) model of subboundary pattern formation in SOI films, (iii) low defect density SOI films by ultra slow scanning of the melt zone, (iv) low defect density SOI films by patterned openings in the cap oxide overlayer.

The microstructure of high-quality recrystallized Si films on SiO2 substrates produced by CO2 laser induced zone-melting has been investigated by high voltage electron microscopy (HVEM). Subgrain boundaries represent the major defects in these recrystallized films. The origin of the subboundaries has been traced to periodic internal stress concentrations occurring at the faceted growth interface. These highly localized stresses cause plastic deformation of the growing single crystal film by nucleation of an array of slip dislocations. The mechanism responsible for the formation of subgrain boundaries has been revealed to be polygonization, where thermally activated dislocations rearrange themselves into the lower energy configuration of the low angle grain boundary.