International Business Machines Corporation

Paul E Cade

Kurt Edward Petersen

Francis S Luecke

Badih El-Kareh

Norman T Gonnella

Albert S Bergendahl

Ick W Kim

A method for forming a master mold for optical storage disks includes thermally growing an oxide or nitride layer on a semiconductor wafer. The thermally grown layer is then coated with a photoresist. The photoresist is exposed to a laser beam to form a data pattern and developed. The oxide or nitride under the developed pattern is etched and the photoresist stripped to provide a semiconductor master mold for optical disks.

Process for forming a master mold for optical storage disks

A method for fabrication of a buried field shield in a semiconductor substrate. A seed substrate is prepared by depositing an epitaxial layer or a seed wafer and then depositing a heavily doped layer and a thin dielectric. The thin dielectric is patterned for contact holes and then a conductive field shield is deposited and patterned. A thick quartz layer is deposited over the field shield and dielectric. A mechanical substrate is anodically bonded to the quartz of the seed substrate and the original seed wafer is etched back to expose the epitaxial layer for further fabrication.

Buried field shield for an integrated circuit

A laser beam is used to scribe an alignment mark on the back side of a lightly doped substrate of a silicon wafer containing an heavily doped internal layer. The wavelength of the laser beam is chosen such that it passes through the lightly doped substrate without absorption but is absorbed in the heavily doped internal layer to produce therein a defect which has the same position as the scribed alignment mark. Subsequent heating of the wafer causes the defect to migrate upwardly through a lightly doped epitaxial layer to the front side of the wafer and produce therein a visible mirror image of the scribed alignment mark.

Laser process for forming identically positioned alignment marks on the

This describes a dual electrode electrostatically deflectable deformographic switch. The switch can be driven by co-incident voltages and can be made to retain and store information. The switch can be used either as a display or a memory and has a number of engineering advantages, for it is a direct drive display which does not need either vacuum envelopes or electron beam drives. Furthermore, greater efficiencies can be realized and no refresh is necessary since the switch will operate in a standby condition. Also only two voltage levels above ground, i.e., a write voltage and a standby voltage, are required. The switch will enable copiers to be directly driven by computers. The switch can also be used as an optical waveguide transmit/receive switch or an accelerometer.

Electrostatically deformographic switches

A smaller, faster, more efficient photo detector cell can be created with improved photo sensitivity in the short wavelength regions, using well known integrated circuit production techniques, by forming the photo sensitive junction of the device in an isolated region of a thin epitaxial layer overlying a thin subcollector so as to use all the current generated in the cell. The cell thus comprises a semiconductor body having an epitaxial layer thereon which is divided into isolated pockets containing a photosensitive junction overlying a subcollector region formed at a depth of less than 10 microns between the substrate and the epitaxial layer. The photo sensitive junction of the device merges with the isolation region so that a single continuous P-N junction surrounds substantially all subcollectors and the isolated pocket of epitaxial material. A device constructed as taught realizes approximately 100% quantum efficiency over a wide range of incident light.

Photo detector cell

The present invention relates to an integrated memory system comprising an array of depletion mode field effect transistors operated in a common control electrode mode to provide an array with the density of metal oxide semiconductor field effect transistor arrays and the speed of bipolar transistor arrays. Each transistor of the array has a gate or control electrode surrounding a channel region of the device which gate is held at a reference potential with respect to the source and drain regions which are selectively biased. The invention can be utilized in both a random access memory and a read only memory mode. The read only mode is somewhat of a simpler structure capable of a higher density than that of the random access. In both cases a low capacity, high density, high speed memory which is self limiting as to current and which uses a lower power requirement than comparable Bipolar memories is realized. The field effect transistors of the invention are readily formed using existing processes that will permit bipolar devices to be made on the same chip.

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Colchester, VT, United States of America

Paul E Cade