Harold H. Hosack

Recent advances in process synthesis for semiconductor devices

Recently, work has been started on a new methodology, called process synthesis, that has the potential to revolutionize integrated circuit (IC) process design in the same way that ASIC and microelectronics manufacturing science and technology (MMST) revolutionized circuit design and factory operation. This paper provides an overview of process synthesis, discusses synthesis methodologies, potential roadblocks to execution of this strategy, and presents recent progress in developing this capability.

A channel-stop-defined barrier and drain antiblooming structure for virtual phase CCD image sensors

A barrier and drain antiblooming (AB) structure that addresses a number of fabrication and operational problems associated with previous structures is discussed. Defects in the AB barriers of previous designs often caused dark columns in the array by draining away all the signal charge from the defective pixel. This design minimizes this serious yield-loss mechanisms by reducing the AB barrier-to-well perimeter to a minimum and by isolating the remaining drain-to-well perimeter with a high-integrity channel stop. A further process economy and yield enhancing feature is that the antiblooming barrier is formed from the same implants as the pixel barrier, insuring that the AB barrier potential is the appropriate value for proper antiblooming action. The fabrication process adds only one mask level to the conventional sensor process flow. The structure preserves all of the prized aspects of barrier and drain AB, high normal and flash overload tolerance, as well as simple system requirements. The structure has been demonstrated in a virtual-phase CCD sensor, and operating results are reported. >

Aperture response and optical performance of patterned-electrode virtual-phase imagers

This report discusses the aperture response and associated optical characteristics for frontside-illuminated, frame-transfer, patterned-electrode, virtual-phase imagers under various operating conditions. These characteristics are of interest in considering the use of these imagers in camera applications. The consequences of the use of semitransparent electrodes for the clocked phase of this new class of devices is discussed, and the implications on MTF, aliasing, and performance in interlaced applications is considered.

Minimum geometry etch windows to a polysilicon surface

Windows of less than 0.1 µm in width on a polysilicon surface are demonstrated. These narrow windows have been produced by the edge etch process. The usefulness of this technique for producing narrow openings in a polysilicon layer is discussed.

A closed form analytic model for separation by implantation of oxygen oxide growth using a joined‐Gaussian approximation

A closed form analytic solution to the growth characteristics of the separation by implantation of oxygen (SIMOX) buried oxide and silicon film, based on a two‐sided Gaussian approximation to the oxygen implant profile in the SIMOX process, is presented. The model used includes the effects of substrate swelling and sputtering due to the implanted oxygen, as well as the effects of saturation of the oxygen density at the stoichiometric SiO2 level in the implanted region. The results of this investigation show that for typical SIMOX implant conditions currently used in high‐current implanters, the total dose of oxygen required to first reach the saturation level is only slightly dependent on the swelling and sputtering effects associated with the oxygen implantation, and that the deviation of the location of the first saturation point from the commonly used implant range can be significantly affected by the implant profile. In addition, it is shown that a ‘‘natural parameter’’ GNsat, where G is the net growt...

Effect of particles on buried oxide defects in SIMOX material

An array of artificial particles composed of silicon dioxide was created by growing a film of SiO/sub 2/ one micron thick on a wafer surface, then patterning and etching the film to create barriers of various sizes and shapes. Two of the more interesting of these shapes are long lines and individual dots. These lines make it practical to analyze the structures by cross-sectional scanning and transmission electron microscopy. The shape of one of the lines after implantation to a dose of 1.8*10/sup 18/ at an implantation temperature of 630 degrees C is shown.<<ETX>>

An analytic solution to SIMOX oxygen implant profiles using joined half-Gaussian distributions

The authors describe the results of an analytic investigation of SIMOX (separation by implanted oxygen) oxide/silicon profiles using a joined half-Gaussian approximation to the instantaneous oxygen implant distribution. The advantage of this approach over computer-generated solutions is that it provides an easy way to see the effects of variations in the physical parameters of the implant process on variations in the features of the resulting SIMOX materials. These results can then be used to relate variations in SIMOX fabrication parameters to resulting variations in final device performance. It is shown that a dimensionless parameter which can be used to gauge several significant features of the implant process is the product of the extension of the silicon surface due to volume expansion from the implanted oxygen and the saturation value of oxygen in the resulting buried oxide.<<ETX>>

Evolution of Buried Oxide “Pipe” Defects Upon Implantation Through Particles in Simox Material

We have investigated the effect of the presence of oxide particles on the surface of silicon wafers during high energy, high dose implantation of oxygen into silicon. It was found that for single implants with doses of 1.5 × 10 18 /cm 2 or 1.8 × 10 18 /cm 2 , such particles produce a non-continuous buried oxide layer in the as-implanted condition as well as after annealing. Etching results showed that no defects, which formed etchable paths through the buried oxide, were produced for particles with diameters 0.43 um or below for the lower dose and 0.53 um for the higher dose.