P. K. Boyer

Laser‐induced chemical vapor deposition of SiO2

We have demonstrated rapid (3000 A/min) photochemical deposition of silicon dioxide from gas phase donor molecules. An ArF (193 nm) laser was used to excite and dissociate gas phase SiH4 and N2O molecules in contrast to earlier work with incoherent mercury lamps. We have achieved 20 times the deposition rate, limited the dissociation volume to a localized region, and minimized the direct impingement of UV photons on the substrate. Although the SiO2 deposition rate was insensitive to substrate temperature from 20 to 600 °C, film quality noticeably improved above 200 °C. Metal‐oxide‐semiconductor capacitors were fabricated and characterized in order to measure SiO2 electrical properties. Film composition was investigated using Auger and infrared spectroscopy techniques and showed that the SiO2 is stoichiometric and contains less than 5% nitrogen.

Low‐temperature refractory metal film deposition

We have deposited uniform films of Mo, W, and Cr over large areas (>5 cm2) using UV laser photodissociation of their respective hexacarbonyls. The depositions were made at room temperature over pyrex and quartz plates, as well as silicon wafers. We have examined the resistivity, reflectivity, stress, and step coverage of these films.

Laser Photolytic Deposition of Thin Films

An excimer laser is used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide, and zinc oxide at low temperatures (100–350deg;C). Deposition rates in excess of 3000 A/min and conformal coverage over vertical walled steps were demonstrated. The films exhibit low defect density and high breakdown voltage and have been characterized using IR spectrophotometry, AES, and C-V analysis. Device compatibility has been studied by using photodeposited films as interlayer dielectrics, diffusion masks, and passivation layers in production CMOS devices. Additionally, we have deposited metallic films of Al, Mo, W, and Cr over large (>5 cm 2 ) areas using UV photodissociation of trimethylaluminum and the refractory metal hexacarbonyls. Both shiny metallic films as well as black particulate films were obtained depending on the deposition geometry. The black films are shown to grow in columnar grains. The depositions were made at room temperature over pyrex and quartz plates as well as silicon wafers. We have examined the resistivity, adhesion, stress and step coverage of these films. The films exhibited resistivities at most ∼20 times that of the bulk materials and tensile stress no higher than 7 × 10 9 dynes/cm 2

Electron beam assisted chemical vapor deposition of SiO2

We have demonstrated electron beam assisted chemical vapor deposition of silicon dioxide films on silicon substrates via electron impact dissociation of SiH4 and N2O gas. Dissociation of reactant gases occurs primarily in the confined planar region of the electron beam created plasma. Electron beam deposited SiO2 films have been categorized in terms of their electrical, physical, and chemical properties.

Effect of surface irradiation, substrate temperature, and annealing on laser deposited silicon dioxide

A pulsed ArF laser is used to photochemically deposit thin films of silicon dioxide on silicon substrates. As the substrate temperature was increased during film deposition, the etch rate, dielectric constant, flatband voltage shift, and hydrogen bonding of the SiO2 film decreased while the refractive index, resistivity, and breakdown voltage increased. The etch rate and infrared absorbance of bonded hydrogen incorporated in the SiO2 film also decreased when surface photons impinged on the growing films or when a post‐deposition anneal was performed.

Photoenhanced thermal oxidation of InP

The growth rate of laser‐photoenhanced thermally grown native oxides of InP in a N2O ambient and its dependence on growth condition are presented. Increased laser power, substrate temperature, and N2O pressure are observed to increase the growth rate. The topography and the composition of these oxides have been studied, using secondary electron microscopy and x‐ray photoemission spectroscopy, respectively. The oxide layers contain In2O3 and a phosphate, probably InPO4. The enhanced growth appears to be caused by both excited oxidizing species and a photon‐enhanced surface reaction.

Thin Film Deposition By UV Laser Photolysis

An ArF excimer laser was used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide and zinc oxide at low temperatures (100-500°C) for microelectronic applications. High depo-sition (>1000 A/Min) rates and conformal step coverage were obtained. The hydrogen bonding, pinhole density, index of refraction, etch rate, and breakdown voltage have been measured for the Si02 and silicon nitride films. The effect of substrate temperature and ArF (193 nm) surface photons on the physical, chemical and electrical properties of Si02 films have been investigated.

Broad‐area electron‐beam‐assisted etching of silicon in sulfur hexafluoride

Silicon etching rates up to 250 A/min have been observed in an electron‐beam‐generated He plus SF6 plasma. The etch rate was found to increase linearly with electron beam current density and to be practically independent of the electron acceleration voltage in the range investigated (170–260 V). Profiles of the resulting features show that etching is anisotropic with a vertical‐to‐horizontal ratio of 2.5 to 3.

Microelectronic Thin Film Deposition By Ultraviolet Laser Photolysis

An excimer laser is used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide, and zinc oxide at low temperatures (100-350°C). Deposition rates in excess of 3000 Å/min and conformal coverage over vertical walled steps were demonstrated. The films exhibit low defect density and high breakdown voltage and have been characterized using IR spectrophotometry, AES, and C-V analysis. Device compatibility has been studied by using photodeposited films as interlayer dielectrics, diffusion masks, and passivation layers in production CMOS devices. Additionally, we have deposited metallic films of Al, Mo, W, and Cr over large (>5 cm2) areas using UV photodissociation of trimethylaluminum and the refractory metal hexacarbonyls. Both shiny metallic films as well as black particulate films were obtained depending on the deposition geometry. The black films are shown to grow in columnar grains. The depositions were made at room temperature over pyrex and quartz plates as well as silicon wafers. We have examined the resistivity, adhesion, stress and step coverage of these films. The films exhibited resistivities at most %20 times that of the bulk materials and tensile stress no higher than 7 x 109 dynes/cm2.

Excitation mechanism of positive column He-Te laser transitions

Using a pulsed afterglow technique, the excitation mechanism of the cw positive column He‐Te laser was investigated and a velocity averaged total destruction cross section of He+ by tellurium was measured to be 1×10−15 cm2. The principle channel for excitation of upper laser levels was seen to be charge transfer collisions between He+ and Te atoms. These results are compared to similar measurements of upper laser levels of the positive column He‐Se laser, and the previous hollow cathode discharge measurements of He‐Te collisions as performed by Alienikov and Ushakov.