Hughes Aircraft Company

USA As Represented by Secretary of the Navy

Accelerators, Inc.

Robert L Seliger

William P Robinson

Victor Wang

James W Ward

Charles M McKenna

J William Ward

William M Clark, Jr

Gregory L Tangonan

Weldon S Williamson

Joseph A Wysocki

John R Bayless

John L Bartelt

Faik S Ozdemir

Hugh McNulty, Jr

Richard P Vahrenkamp

James E Wood

Gerald B Rosenberg

Paul A Sullivan

Laurence C Dumage

A security system and method for IC circuits has at least one additional circuit element that does not contribute toward the IC's circuit function, but inhibits proper functioning of the IC in case of an attempted copying or other unauthorized use. The identity of the additional circuit elements is disguised by forming them with the visible appearance of an apparent element but with a physical modification which is not readily visible but causes them to function in a different manner, by providing different ICs with unique control codes, or both. Physical modifications not readily visible to a copyist include very narrow open circuit cuts in metallized connection lines, preferably with a focused ion beam (FIB) or laser beam; and/or disordering the lattice structure or changing the doping level of a semiconductor region, preferably with a FIB; and/or injecting electrical charge into a semiconductor region, preferably with an electron beam. The additional elements can be formed into a control code subcircuit for the IC, with the code disguised by the use of apparent elements. ICs can be grouped into an operational ring in which control codes are transmitted serially through the ring, and the invention can be applied to a combined hardware/software system. Individual copies of the software, preferably the operating system software, contain the unique control codes required by the modified ICs and the algorithms to interact with the system hardware for the purposes of transmitting, receiving, and authenticating the control codes.

Method and apparatus for securing integrated circuits from unauthorized

An ion beam microfabrication system is described which is capable of operating in either a flooded beam mode, in which a relatively high current beam is used to yield a rapid throughput, or in a low current, high resolution focused ion beam mode. With a focused beam a small, relatively low current ion spot is deflected in a predetermined pattern over a portion of the wafer to produce more detailed patterning that is not achievable in the flooded beam mode. A lens is added to the beam column to modify the beam collimation between the focused and flooded modes, and switching between modes is accomplished by simply actuating or de-actuating the lens. The beam is formed with a larger acceptance angle and total current in the flooded than the focused mode.

Hybrid focused-flood ion beam system and method

Focused ion beam microfabrication column (10) produces an ion beam from ion source (12), focuses the beam by objective lens (24) onto the plane of electrode (36). ExB filter (44) separates out the ion species at a low energy portion of the beam. The beam of selected species is first accelerated by energy central lens (38) which has a controllable potential for controlling the final beam energy to the target. The beam is accelerated by final accelerator lens (54) and is demagnified and focused on the target by that lens. Beam deflector (64) deflects the beam for programmed ion beam work on the target (60).

Focused ion beam microfabrication column

Two lens focused ion beam column (10) has an accelerating lens (20) which carries a potential to focus an image of the liquid metal ion source (14) on the mass analyzer slit (26) with a magnification of about unity. Munro lens (36) accelerates the beam of selected ion species and demagnifies the image through a long working distance to provide an ion writing spot of less than about 1000 .ANG. size.

Focused ion beam column

The specification discloses a process for accurately aligning a chosen member with a focused beam of radiation or for aligning two chosen members with each other. A set of alignment marks having a predetermined spatial pattern is first provided on the surface of each member. Next, a detection signal is generated from the set of alignment marks, comprising a serial electronic signal as a function of time and containing serial information corresponding to the relative position of each mark in the set of alignment marks. Then, the detection signal is electronically processed to generate an alignment signal with a high signal-to-noise ratio. Next, the alignment signal is compared to a reference signal signifying a predetermined criterion of alignment, to generate an error signal which is indicative of the extent of misalignment. Finally, lateral movement of one chosen member is produced in response to the error signal until accurate alignment of the chosen member with the focused beam of radiation or of the two chosen members with each other is achieved.

Alignment process using serial detection of repetitively patterned

Thermionic cathode 12 for a plasma ion source 10 has tungsten wire 64 advanced by wheels 56 from supply 50 to take-up spool 58. In chamber 48, the active cathode region 64 acts with anode 16 to supply electrons for ionizing a fuel gas so the ions are discharged from slit 18 for acceleration, separation and implantation.

Filament dispenser cathode

The specification describes a process for masking a collimated ion beam for either forming resist patterns on selected substrates or for other selective ion implantation purposes. This process includes the steps of forming an ion absorption mask on the surface of a hyper thin supporting membrane and thereafter aligning the mask with a substrate having a layer of resist thereon. Next, the ion absorption mask is exposed to a beam of ions which pass through certain areas of the absorption mask and into the resist layer to thereby expose selected regions in the resist layer (i.e., to increase or decrease the solubility of the resist to a chosen developer). In a specific embodiment of the invention, the ion absorption mask is formed by initially anodizing an aluminum substrate to form a thin coating of aluminum oxide thereon, and thereafter depositing a gold mask on one surface of the aluminum oxide coating. Certain regions of the aluminum substrate beneath the gold mask are removed to expose the aluminum oxide immediately beneath the gold mask, thereby forming a thin taut aluminum oxide membrane which supports the gold ion absorption mask.

High resolution masking process for minimizing scattering and lateral

Alloys suitable for use in liquid metal field ionization ion sources are provided. Such sources include an anode electrode for supporting an ion emitter comprising an alloy in the liquid state. The source further comprises means for generating an ionizing electric field and a reservoir for the liquid metal, ions of which are to be emitted by the source. The alloys are selected from the group consisting of (a) metal-metalloid alloys comprising about 10 to 30 atom percent of at least one metalloid element, the balance at least one transition metal element, (b) early transition-late transition alloys comprising about 30 to 85 atom percent of at least one early transition metal, the balance at least one late transition metal, and (c) Group II alloys comprising about 35 to 80 atom percent of at least one Group II element, the balance at least one metal element. Ions generated in liquid metal ion sources form a high brightness ion beam, which permits focusing a beam of emitted ions to a submicrometer spot. The ions may be used to alter material properties by ion implantation such as to dope semiconductors, to form ohmic contacts, to improve wear and corrosion resistance in metal surfaces and by sputter etching thin films such as metals, dielectrics and semiconductors.

Alloys for liquid metal ion sources

A plurality of beam generating units 76, 78, 80 and 82 each produces separated rectangular ion beams for implantation onto a targets 52 and 54 rotatively moving therepast. Each rectangular footprint is long in the direction of motion and is scanned transversely to the direction of motion. A plurality of beam generating units can be positioned adjacent to each other to multiply implant targets because of the compact structure of the separated ion source.

Ion implantation system

A high-resolution high-throughput ion beam lithography process and apparatus for exposing a large area target by a step-and-repeat process which accommodates lateral wafer distortions in the target and optimizes the resolution, throughput, yield, and cost of the process. First there is provided: a target having predetermined segments defined thereon, with the area of each segment being chosen to optimize the resolution, throughput, yield, and cost of the process; a mask placed in proximity to said target, to define the patterned ion beam; a collimated ion beam with a diameter approximately equal to the diameter of the mask, which is projected through the mask to form the patterned ion beam; and a means for aligning the mask and a selected segment of the target. The size of the mask is equal to or larger than the size of one of the predetermined segments of the target and the pattern area of the mask is smaller than the area of one of the selected segments of the target. Next, the mask is aligned with a first selected segment of the target and this first segment is exposed to the patterned ion beam, formed by projecting the collimated ion beam through the mask. Then, the mask is aligned with a second selected segment of the target and this second segment is exposed to the patterned ion beam. Thus, selected segments of the target are exposed to the projected ion beam pattern in a step-and-repeat manner.

Ion beam lithography process and apparatus using step-and-repeat exposure

The first plasma discharge chamber of the dual discharge plasma device contains an electron emitter and a first anode and contains gas at a sufficiently high pressure that the discharge voltage in the first chamber is below the sputtering threshold. The second chamber has a main anode and receives a plume of plasma from the first chamber. The main anode operates at a voltage above the sputtering threshold with a respect to the first anode and the gas in the second chamber is at a low enough pressure for a conventional low pressure plasma discharge which is used as an ion source.

Dual discharge plasma device

The ion implantation system includes a separate vacuum housing 102 for the ion source and the target chamber 118. The ribbon beam ion source 10 provides a footprint 162 on the wafer wheel 126 of such shape as to permit short traverse of the wafer wheel 126 for full wafer scan.

The separated ion source combines an ion source and a magnetic mass separator within a single magnetic field geometry. The preferred ion source has a low voltage Penning discharge configuration and produces a charged particle beam in the form of a ribbon with a rectangular cross section.

Separated ion source

The specification describes a process for minimizing ion scattering and thereby improving resolution in ion beam lithography. First, a substrate coated with a layer of ion beam resist is provided at a chosen spaced distance from an ion beam source. Next, a monocrystalline membrane with a patterned ion absorption region is positioned at a predetermined location between the substrate target and the ion beam source. The patterned ion absorption region may be either an ion absorption mask, such as gold, deposited on the surface of the monocrystalline membrane, or a pattern of ion-damaged regions within the monocrystalline membrane. Finally, a collimated wide area ion beam is passed perpendicular to the surface of the membrane and through crystal lattice channels therein which are exposed by the patterned ion absorption region and which extend perpendicular to the membrane surface. The parallel paths established by the channels in the membrane provide low resistance paths to the passage of ion beams and consequently minimize the angle of deflection of the ions passing from the membrane to the target resist layer.

Growing community of inventors

Agoura, CA, United States of America

Robert L Seliger