American Semiconductor Corporation

Douglas R Hackler, Sr

Stephen A Parke

Dale G Wilson

Richard Alan Hayhurst

Kelly James DeGregorio

John Eugene Berg

Randall S Parker

Richard L Chaney

Michael Paul Goldston

The described method enables removal of any flexible material from a temporary carrier for transfer to another surface. In particular, a semiconductor wafer is commonly held by a temporary adhesive to a carrier substrate for support during a variety of processing steps, including thinning of the semiconductor device layer. Subsequent to processing, the described method attaches the ultra-thin device layer to a roll of tape for removal from the temporary adhesive, followed by transfer to a demount roller, which then releases it onto a desired permanent surface. Utilizing the flexible nature of the ultra-thin device layer, the sequence of rollers is able to peel it from the temporary adhesive without any need for laser release processing or chemical adhesive removal while maintaining the thinned wafer in a planar form during processing. This transfer supports operations that include a change of orientation, such as from face up to face down.

Method of demounting thin semiconductor devices

The described Flexible Micro-Module (FMM) is a device that is made possible by the application of ultra-thin flexible single crystalline ICs. The FMM integrates the IC(s), insulating contact substrate, vias for connections to pads, and external contacts into a single device. The thin and flexible FMM eliminates the need for wire bonds and card body cavities in smart card assemblies, and accommodates applying larger ICs to smart cards than what is possible with conventional micro-modules.

Flexible micro-module

Three-dimensional flexible photonic integrated circuits on silicon are fabricated in semiconductor wafer form and then transferred to Silicon-on-Polymer (SOP) substrates. SOP provides flexibility for conformal mounting with devices capable of maintaining performance when dynamically deformed to allow routing of light in x, y and z directions. Bonding a wafer or individual die of III-V semiconductor, such as Gallium Arsenide or similar photonic material, to the flexible silicon creates an active region for lasers, amplifiers, modulators, and other photonic devices using standard processing. Mounting additional photonic devices to the opposite side of a flexible photonic waveguide produces a stack for three-dimensional devices. Multiple flexible photonic waveguides may be stacked to increase functionality by transferring light between stacked waveguides. The flexible photonic circuit allows for integration of photonic devices such as low threshold lasers, tunable lasers, and other photonic integrated circuits with flexible Complementary Metal Oxide Semiconductor (CMOS) integrated circuits.

Flexible 3-D photonic device

This method of waferscale packaging produces finished integrated circuits (ICs) individually completely encapsulated with environmentally protective packaging material while still in the wafer format. Following conventional semiconductor fabrication of chips at the wafer level and prior to their separation, a first polymer is applied to the front surface of the wafer with allowance for contact holes. A carrier wafer is attached to the exposed polymer. The original substrate is removed and the devices are separated by cutting through the semiconductor layer and the first polymer. A second polymer is applied to cover the exposed backside of the devices and to fill the cut spaces between them, thereby sealing the remaining five surfaces of the chips. The second polymer layer may also include contact holes for access to the back side of the device chips. A second singulation cutting leaves the chips on the wafer prepared for a pick-and-place operation.

Method of producing encapsulated IC devices on a wafer

Semiconductor On Polymer (SOP) is a flexible ultra-thin substrate that can be used as the starting material for CMOS, MEMS or Complex Interconnects such as an interposer. The described process results in a flexible SOP device with open bond pads. After deposition of a liquid polymer onto a semiconductor substrate, the polymer is converted to a solid, creating a new substrate that is temporarily bonded to a carrier wafer. The semiconductor layer is then etched to be ultra-thin and highly uniform, specifically, a single crystalline silicon layer. Following fabrication of devices and interconnects on the polymer substrate, the ultra thin wafer is released from the carrier wafer in substrate form to be used whole or tiled for subsequent assembly. Among other advantages, the flexible format of the SOP substrate enables low resistance 3-D interconnects, and provides for a significant increase in performance due to a reduction in parasitic capacitance.

Semiconductor on polymer substrate

This interposer provides interconnections between stacked layers of circuits, which may include integrated circuits, PC boards, and hybrid substrates. Fabricated as an integrated circuit itself using readily available process steps, this interposer uses single and dual-damascene layers to increase the density of usable interconnections on both its top and bottom surfaces. Access from a top surface to a bottom surface is provided by conductive through-vias that may be placed at a high density. For even greater density, interconnections may be routed within silicon trenches, while damascene processing reduces the total number of steps required for fabrication. The described techniques may be used to create double-sided integrated circuits.

Triple-damascene interposer

Memory cells are constructed from double-gated four terminal transistors having independent gate control. DRAM cells using one transistor to implement a Ferroelectric FeRAM are described. Top gates provide conventional access while independent bottom gates provide control to optimize memory retention for given speed and power parameters as well as to accommodate hardening against radiation. In a single transistor cell without a capacitor, use of the bottom gate allows packing to a density approaching 2 F. Using a ferroelectric material as the gate insulator produces a single-transistor FeRAM cell that overcomes the industry-wide Write Disturb problem. The memory cells are compatible with SOI logic circuitry for use as embedded RAM in SOC applications.

Single transistor memory with immunity to write disturb

Memory cells are constructed from double-gated four terminal transistors having independent gate control. DRAM cells may use one, two or three transistors. Single transistor cells are constructed either with or without a bit storage capacitor, and both NAND- and NOR-type Non-Volatile NVRAM cells, as well as Ferroelectric FeRAM cells, are described. For all cells, top gates provide conventional access while independent bottom gates provide control to optimize memory retention for given speed and power parameters as well as to accommodate hardening against radiation. In a single transistor cell without a capacitor, use of the bottom gate allows packing to a density approaching 2 F. The memory cells are compatible with SOI logic circuitry for use as embedded RAM in SOC applications.

Double-gated transistor memory

A high quality imager is constructed using a silicon-on-insulator (SOI) process with sensors fabricated in the SOI substrate and isolated by the buried oxide (BOX) from associated readout circuitry in the SOI layer. Handle windows are opened in the SOI device layer for fabrication of the sensors in the handle layer substrate and then closed prior to processing in the device layer. By keeping the buried oxide layer intact, the described technique allows for independent processing of sensors and readout circuitry so that each is optimized with regard to thermal and dopant properties without concern for degradation of the other. The process is compatible with the fabrication of readout circuitry using transistors having independent double-gates, which offer simultaneous advantages in scalability, low power and low noise. Photodiode sensors are shown with allowance for many other types of sensors. The process easily accommodates hardening against radiation.

Double-gated sensor cell

Memory cells are constructed from double-gated four terminal transistors having independent gate control. DRAM cells may use one, two or three transistors. Single transistor cells are constructed either with or without a bit storage capacitor, and both NAND- and NOR-type Non-Volatile NVRAM cells, as well as Ferroelectric FeRAM cells, are described. For all cells, top gates provide conventional access while independent bottom gates provide control to optimize memory retention for given speed and power parameters as well as to accommodate hardening against radiation. In a single transistor cell without a capacitor, use of the bottom gate allows packing to a density approaching 2 F. Using a ferroelectric material as the gate insulator produces a single-transistor FeRAM cell that overcomes the industry-wide Write Disturb problem. The memory cells are compatible with SOI logic circuitry for use as embedded RAM in SOC applications.

Independently-double-gated transistor memory (IDGM)

A family of logic circuits is constructed from double-gated four terminal transistors having independent gate control. First and second inputs to each logic element are independently coupled to the top and bottom gates of a transistor. The output voltage developed at either the source or drain represents an output logic state value according to the designed logic element. In a dynamic configuration the drain is precharged to an appropriate voltage. Complementary static CMOS configurations are also shown. Bottom Gates not driven by logic inputs or control signals may be biased to control the speed and power of the described logic circuits. Specific designs are given for AND, NAND, XOR, XNOR, OR and NOR combinational logic elements.

Independently-double-gated combinational logic

This independent double-gated transistor architecture creates a MOSFET, JFET or MESFET in parallel with a JFET. Its two gates may be configured to provide a four-terminal device for independent gate control, a floating gate device, and a double-gate device. First and second insulating spacers are disposed on opposing sides of the top gate with the first spacer between the source and the top gate and the second spacer between the drain and the top gate. Source and drain extensions extend proximate to the spacers and couple to the channel. The spacers shield the channel from the field effect of the source and drain and further resist compression of the channel by the source and drain. Truly independent control of the two gates makes possible many 2-, 3- and 4-terminal device configurations that may be dynamically reconfigured to trade off speed against power. The resulting transistors exhibit inherent radiation tolerance.

Independently-double-gated field effect transistor

An OR gate circuit includes double-gated four terminal transistor with independent gate control. First and second inputs are independently coupled to the top and bottom gates of the transistor. The drain is coupled to an output and precharged to a low voltage. An input to either the top or bottom gates results in a high voltage to the drain and an output value of 1.

Double-gated transistor circuit

A double-gated transistor architecture provides a four terminal device for independent gate control, a floating body device, and a dynamic threshold device. The channel may have a U-shaped cross-sectional area to increase the channel length and gate control. First and second insulating spacers are disposed on opposing sides of the top gate such that the first spacer is between the source and the top gate and the second spacer is between the drain and the top gate. The source and drain include extensions that extend proximate to the spacers and couple to the channel. The spacers shield the channel from the field effect of the source and drain and further resist compression of the channel by the source and drain.

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Boise, ID, United States of America

Douglas R Hackler, Sr