International Business Machines Corporation

Dieter P Kern

Kevin K Chan

Sang Hoo Dhong

Johann Greschner

Thomas Bayer

Johann W Bartha

Young Hoon Lee

Roland R Stoehr

Tai-Hon P Chang

Volker Mattern

Kim Yang Lee

Robert B Laibowitz

Raman Gobichettipalayam Viswanathan

Stephen A Rishton

Michael G Rosenfield

Walter W Molzen, Jr

Fritz-Jurgen Hohn

Porter Dean Gerber

Lawrence P Muray

Mark I Lutwyche

Phillip J Coane

Christopher J Ashton

Fine epitaxial patterns of yttrium barium copper oxide on a strontium titanate substrate are provided by using a silicon nitride mask to define the pattern to be formed. A thin film of yttrium barium copper oxide is placed on the silicon nitride mask and exposed portions of strontium titanate substrate. Where the yttrium barium copper oxide is in contact with the silicon nitride mask, it is nonepitaxial in crystal structure. Where the yttrium barium copper oxide contacts the strontium titanate substrate in the openings, it is epitaxial in structure forming fine patterns that become superconducting below the critical transition temperature. A channel can be formed in the strontium titanate substrate. The epitaxial yttrium barium copper oxide pattern is formed in this channel to minimize possible exposure to the silicon nitride mask.

Selective epitaxial growth of high-T.sub.C superconductive material

A flash EEPROM is produced comprising multiple MOS cells. In each cell, programming and erasing are performed through tunneling from the write gate to the floating gate and by tunneling from the floating gate to the erase gate, respectively. The directional dielectric employed is a multilayered structured (MLS) oxide, where thin oxide and thin polycrystalline silicon form alternating layers. The layering is asymmetric: that is, either the uppermost or bottommost layer is thicker than the other layers. As a result of this structure, the oxide exhibits directionality, that is, the tunneling is easier in one direction than the reverse direction, and significantly enhances the tunneling phenomena (tunneling current can be observed at as low as 4.7 V). In addition, the MLS oxide can be fabricated having different dielectric constants. The directionality, coupled with the separate write and erase gates, gives the new flash EEPROM cell a number of advantages: it is low-voltage operable, it is highly resistant to disturbance and has an easily scalable structure (that is, it can be made to operate at any given voltage within a specified scale).

Method for manufacturing a memory cell

Asymmetric multilayered dielectric material and a flash EEPROM using the

Disclosed is a vacuum reactor for etching substrates having a low thermal conductivity to a high degree of etch rate uniformity, wherein the substrates to be etched are arranged in a holder at a predetermined spacing from the cathode to which RF energy is applied. According to a preferred embodiment of the invention, the cathode is raised in the area of the substrate to be etched to within a spacing of about 0.2 mm from the bottom side of the substrate. The cathode is made of aluminium, and is provided in the area of the substrate to be etched with a layer which acts as a black radiator. The heat formed during RIE is removed by radiation, and the radiation reflected from the cathode to the substrate is absorbed by the layer. Also disclosed is a method of etching substrates having a low thermal conductivity, in particular plastic substrates.

Apparatus for plasma or reactive ion etching and method of etching

Method of etching substrates having a low thermal conductivity

The present invention is directed to a method for selectively scaling the dimensions of a field emission electron gun. The electron gun includes a field emission tip followed by a dual electrode immersion lens. The lens consists of two planar electrodes separated by a dielectric layer. A well defined circular hole is present at the center of each electrode and the dielectric layer. A high scaling factor is applied to the region consisting of the first electrode and the emission tip, reducing the first electrode thickness and bore diameter and the distance between the tip and first electrode to the micrometer range. A weaker scaling factor is applied to the bore diameter of the second electrode and the spacing between the electrodes such that the second electrode bore diameter and distance between the electrodes are approximately equal and are greater than the first electrode thickness and bore diameter and the distance between the tip and first electrode.

Method for selectively scaling a field emission electron gun and device

A proximity effect correction method for electron beam lithography suitable for high voltages and/or very dense patterns applies both backscatter and forward scatter dose corrections. Backscatter dose corrections are determined by computing two matrices, a 'Proximity Matrix' P and a 'Fractional Density Matrix' F. The Proximity Matrix P is computed using known algorithms. The elements of the Fractional Density Matrix are the fractional shape coverage in a mesh of square cells which is superimposed on a pattern of interest. Then, a Dose Correction Matrix D is computed by convolving the P and F matrices. The final backscatter dose corrections are assigned to each shape either as area-weighted averages of the D matrix elements for all cells spanned by the shape, or by polynomial or other interpolation of the dose correction field defined by the D matrix. The D matrix also provides a basis for automatic shape fracturing for optimal proximity correction. Optionally, forward scattering correction may be included in the correction process. Forward scattering correction consists of boosting the dose applied to shape i by a factor b.sub.i. These boost factors are computed in a separate and independent step which considers only forward scattering. They are combined with those resulting from the backscatter correction scheme either by simple multiplication to form the final correction factors, or by inputting them to the backscatter correction scheme as numerical weights for each shape.

Method for correcting proximity effects in electron beam lithography

The electron potential of an electron beam is switched between different values without moving the focal plane by effectively changing the axial position of the electron source at the same time that the electron potential is changed. The effective change in axial position of the electron source exactly compensates for the altered effectiveness which magnetic lenses have upon an electron beam of altered electron potential such that the final focal plane remains at the same position without adjusting the field strength of any magnetic lens.

Electron beam potential switching apparatus

Growing community of inventors

Amawalk, NY, United States of America

Dieter P Kern