Gabriel Lorimer Miller

Contactless measurement of semiconductor conductivity by radio frequency‐free‐carrier power absorption

It is shown that, under suitable conditions, the power absorbed by a thin semiconductor slice in an oscillating magnetic field is accurately proportional to the material conductivity. The magnitude of this power absorption can be used to determine the conductivity by coupling the semiconductor to an amplitude‐stabilized marginal oscillator and noting the power needed to maintain the demanded level of oscillation. Instruments of this type have been constructed exhibiting ∼1% linearity over a 100:1 range of sample conductivity, a resolution of ∼1 in 104 and a limiting sensitivity of ∼10−5 mho/⧠. The method may be applied to the measurement of essentially any conducting material from semiconductors to metals.

Incorporation of implanted In and Sb in silicon during amorphous layer regrowth

Annealing of indium and antimony implanted into silicon at doses sufficient to produce an amorphous layer (1014–1015 ions cm−2) has been studied using high‐energy Rutherford backscattering. Annealing of these amorphous layers followed the behavior reported for layers formed by silicon ion bombardment and has a pronounced influence on both the retention and lattice‐site location of the impurities, with marked differences between substrates of (111) and (100) orientation. Following epitaxial regrowth on both orientations at 550 °C substitutional concentrations in excess of the solid solubility were observed. Impurity redistribution was not detected at this annealing temperature nor for 940 °C annealing of (100) and (110) substrates, but migration toward the surface was observed after high‐temperature annealing of (111) material. This resulted in a loss of ∼60% of implanted In after 1 h annealing, whereas antimony accumulated behind the native thermal oxide. Impurity atoms continued to migrate after lattice ...

A rocking beam electrostatic balance for the measurement of small forces

There exists interest in the measurement of small forces for applications such as microtopography of semiconductor devices and atomic force microscopy. A new method is introduced here in which a small silicon beam, that is acted on by the external force of interest, has its position sensed by an rf phase shift technique. The position information in turn is fed back via electrostatic forces to continuously rebalance the beam about its central support. This force‐feedback approach provides high sensitivity, submillisecond response, inherent force calibration, and electronically controlled stiffness.

Resonant phase shift technique for the measurement of small changes in grounded capacitors

A simple technique has been developed for the high resolution measurement of small changes in capacitors which have one grounded electrode. The capacitor is arranged to be the tuning element in a series resonant LC tank circuit that is driven by a transistor emitter follower. Signal information is provided by observing the phase shift in the transistor collector current that results from any small change in the capacitor value. Implementation is simple, readily analyzable, provides good diagnostics, is easily multiplexed into arrays, and has potential applications in a number of areas including high resolution proximity sensing, capacitive topography, atomic force microscopy, and capacitor microphones.

Pulse nonlinearity measurements on thin conducting films

A new pulsed nonlinearity measurement is described and applied to the characterization of thin‐film conductor stripes. The method is based on the phenomenon of ’’baseline shift’’, and is substantially simpler than the already familiar third‐harmonic method yet, at least potentially, just as sensitive. A model is proposed in which the observed nonlinearity is attributed to the temperature rise accompanying current in conductors and the associated resistance change. Good quantitative agreement has been obtained with predictions based on the model. A specific application of this method to reliability testing has been found in magnetic bubble memories, the lifetime of which correlated closely with pulse nonlinearity measurements.

An optical rangefinder for autonomous robot cart navigation

A simple, low cost, infra-red rangefinder has been developed for investigation of autonomous robot cart navigation in factories and similar environments. A 2mW 0.82μ LED source (not a laser) is 100% amplitude modulated at 5MHz and used to form a collimated 1″ diameter transmit beam that is unconditionally eye-safe. Returning scattered radiation is focussed by a 4″ diameter coaxial Fresnel lens onto a p-i-n silicon photodiode. Range is determined from the phase shift between the 5MHz modulation on the transmitted and received signals. Use of a rotating mirror provides 360° polar coordinate coverage of both distance and reflectance out to ∿20 ft. around the vehicle. Both radial and angular resolution correspond to ∿1 inch at a ranging distance of 5 ft., with an overall bandwidth of ∿lKHz. The ranging resolution at 20 ft. is ∿2.5 inches, which is close to the theoretical limit possible for the radiated power, bandwidth, optics and receiver employed. The system is capable of reading wall bar codes “on the fly” and is in addition capable of simultaneously ranging and acting as a wideband optical communication receiver. Total parts cost for the optical transmitter, Fresnel lens, receiver and all the electronics is <

Characterization of Ion-Implanted Si Rapidly Annealed with Incoherent Light

200. The remaining major parts, consisting of the rotating mirror, ring mounting, motor and incremental encoder, cost <

Electrical properties of laser annealed silicon

500.

Charge collection microscopy of laser annealed silicon

Irradiation of Si wafers for 5 to 10 sec with high intensity tungsten halogen lamps produces complete recovery of the displacement damage resulting from ion implantation. Data for two different thermal cycles are presented, with As and B implant doses ranging from 10 13 to 10 16 ions cm −2 . Sheet resistance measurements combined with Rutherford backscattering indicate full electrical activation of dopants with very little diffusion. Carrier lifetimes measured by a photoconductive method and by diode reverse recovery compare favorably with furnace annealing data, and capacitance transient spectroscopy reveals a low density of defects in the junction depletion region. These results combined with the inherent advantages of low cost and high efficiency make Rapid Thermal Annealing ideally suited for VLSI device fabrication.

A technique for investigating the properties of surfaces, thin films, and interfaces by means of a mechanical marginal oscillator

The role of electrically active defects in determining the quality of laser annealed silicon is investigated by characterization of surface and substrate material. Both solid and liquid phase annealing regines are studied. Capacitance transient spectroscopy, photoconductive lifetime, diode reverse recovery lifetime, sheet resistance and angle lap‐spreading resistance measurements are compared. The importance of laser parameters and substrate material are assessed. A prognosis for the application of laser annealing to p‐n silicon junction device fabrication is given.