Leland Stanford Junior University

Mark J Zdeblick

Thomas R Albrecht

Shinya Akamine

Thomas E Carver

Calvin F Quate

A dielectric cantilever arm stylus with an integrally formed pyramidal tip is provided. The tip is molded in a pyramidal pit etched in a later-removed (100) silicon substrate. An integrally-formed cantilever arm is also formed as the tip is being formed. Various thin film materials form the cantilever arm and the tip. In one embodiment of the invention, the dielectric is silicon nitride. The cantilever arm is anodically bonded to a glass block.

Microfabricated cantilever stylus with integrated pyramidal tip

Integrated mass storage device

There is disclosed herein an integrated scanning tunneling microscope and an integrated piezoelectric transducer and methods for making both. The device consists of one or two arm piezoelectric bimorph cantilevers formed by micromachining using standard integrated circuit processing steps. These cantilevers are attached to the substrate at one area and are free to move under the influence of piezoelectric forces which are caused by the application of appropriate voltages generated by control circuitry and applied to pairs of electrodes formed as an integral part of the bimorph cantilever structure. The electric fields caused by the control voltages cause the piezoelectric bimorphs to move in any desired fashion within ranges determined by the design. The bimorph cantilevers have tips with very sharp points formed thereon which are moved by the action of the control circuit and the piezoelectric bimorphs so to stay within a very small distance of a conducting surface. The movements of the tip can be tracked to yield an image of the surface at atomic resolution

Integrated scanning tunneling microscope

Method of forming microfabricated cantilever stylus with integrated

An integrated scanning tunneling microscope and an integrated piezoelectric transducer and methods for making both. The device consists of one or two arm piezoelectric bimorph cantilevers formed by micromachining using standard integrated circuit processing steps. These cantilevers are attached to the substrate at one area and are free to move under the influence of piezoelectric forces which are caused by the application of appropriate voltages generated by control circuitry and applied to pairs of electrodes formed as an integral part of the bimorph cantilever structure. The electric fields caused by the control voltages cause the piezoelectric bimorphs to move in any desired fashion within ranges determined by the design. The bimorph cantilevers have tips with very sharp points formed thereon which are moved by the action of the control circuit and the piezoelectric bimorphs so to stay within a very small distance of a conducting surface. The movements of the tip can be tracked to yield an image of the surface at atomic resolution.

Method of making an integrated scanning tunneling microscope

A variable focal length lens integrated onto a silicon wafer. A light transmitting material such as gas or liquid is entrapped in a cavity in the wafer. The cavity has a flexible, light transmitting wall. The wall provides one surface of the lens. When the material inside the cavity is heated or cooled, the wall flexes and the focal length of the lens changes. The lens is suitable for use in temperature and pressure sensors, fiber optic communication networks, optical computers, and other applications.

Integrated variable focal length lens and its applications

There is disclosed herein an integrated scanning tunneling microscope and an integrated piezoelectric transducer and methods for making both. The device consists of one or two arm piezoelectric bimorph cantilevers formed by micromachining using standard integrated circuit processing steps. These cantilevers are attached to the substrate at one area and are free to move under the influence of piezoelectric forces which are caused by the application of appropriate voltages generated by control circuitry and applied to pairs of electrodes formed as an integral part of the bimorph cantilever structure. The electric fields caused by the control voltages cause the piezoelectric bimorphs to move in any desired fashion within ranges determined by the design. The bimorph cantilevers have tips with very sharp points formed thereon which are moved by the action of the control circuit and the piezoelectric bimorphs so to stay within a very small distance of a conducting surface. The movements of the tip can be tracked to yield an image of the surface at atomic resolution.

A microfabricated microscope assembly including a piezoelectric bimorph cantilever arm mounted at one end to a first substrate. The free end of the canitlever arm has a tip mounted thereto for scanning a scanned surface mounted on a second substrate. The cantilever arm and the substrate are configured to carry out a predetermined write or read mode of operation, such as scanning tunneling microscopy or atomic force microscopy. The two substrates are spaced apart a fixed distance by spacer feet which project from one of the substrates and which have their ends fixed to ther surface of the other substrate by eutectic, aniodic, or adhesive bonding. An array of microfabricated microscope assemblies is formed using a plurality of individual assemblies. A number of different write/read modes of operation are accommodated, such as charge storage, molecular attachment, or magnetic domains. An array of piezoelectric cantilever arms having tips fixed to the free ends thereof and mounted to a substrate form are used to scan a scanned surface. The array is moved laterally with respect to the scanned surface using mechanical actuators as micropositioners for coarse positioning and using the piezoelectric cantilever arms for fine positioning.

Microfabricated microscope assembly

A cantilever stylus with an integrally formed conical tip is provided for atomic force microscopy AFM. The method for forming a stylus includes forming a circular masking pattern on the surface of a silicon substrate and anisotropically etching the silicon to form a post under the masking pattern. The post is then isotropically etched to produce a conical silicon tip mold. In one embodiment of the invention the silicon substrate and the conical silicon tip mold are thermally oxidized to form a cantilever stylus having including a cantilever arm with a conical tip fixed to its free end. In another embodiment of the invention the silicon substrate and the conical silicon tip mold are coated with a thin film of a dielectric material to form a cantilever stylus with a conical tip. In this embodiment the backside of the stylus is coated with a conductive material and a strong electric field is applied to the tip to cause electromigration of the conductive material to the point of the tip.

Microfabricated cantilever stylus with integrated conical tip

A method of making an integrated, microminiature, electric-to-fluidic valve. The method comprises, in one embodiment, anisotropically etching a cavity in a silicon wafer to form a thin membrane at the bottom of a trench. Then a second wafer is etched to form an exit path surrounded by a valve seat positioned such that when these two wafers are sandwiched together, the valve seat lies under the membrane. An input passageway joining a manifold cavity formed around the valve seat is then etched in the surface of the second wafer which will mate with the diaphragm side of the first wafer. The two wafers are then bonded together after suitable alignment. A third pyrex wafer is then coated with a resistor material which will be over the cavity in the first wafer when the first and third wafers are bonded together. Conductive leads and wire attach pads are also formed. Finally, a fill hole is etched into the third wafer over the position of the cavity such that the cavity can be filled. The first and third wafers are then bonded together to complete the valve.

Method of making an integrated, microminiature electric-to-fluidic valve

A pressure regulator integrated in a sandwich of pyrex and silicon wafers. A first integrated valve comprising a silicon wafer in which there is etched a cavity so as to leave a flexible membrane of silicon is sandwiched between two other wafers which are usually pyrex. One of the pyrex wafers has a resistor pattern etched thereon in a location such that the resistor pattern is enclosed by the walls of the cavity when the pyrex wafer is bonded to the silicon wafer. The other pyrex wafer has a valve seat etched adjacent to the membrane in the silicon wafer. The cavity is filled with a fluid which, when heated, raises the vapor pressure in the cavity so as to cause the membrane to flex and change the spacing between the membrane and the valve seat thereby regulating flow. A second integrated valve has the same structure. One of these valves is coupled to a high pressure source and the other is coupled to a low pressure sink. Both valves are coupled to an output channel which has a capacitive pressure sensor integrated therein. Signals from this pressure sensor are used to control the energy applied to the resistors in the first and second valves to vary the area of the channels through the two valves coupling the output channel to the high pressure and low pressure sources.

Integrated, microminiature electric to fluidic valve and pressure/flow

There is disclosed herein an apparatus for converting control signals of an electrical or optical nature of any other type or signal which may be converted to a change of temperature of a fixed volume of material trapped in a chamber to flexure of a membrane forming one wall of the chamber. Typically the device is integrated onto a silicon wafer by anisotropically etching a trench into said wafer far enough that a thin wall of silicon remains as the bottom wall of the trench. In some embodiments, polyimide is used as the material for the membrane. The trench is then hermetically sealed in any one of a number of different ways and the material to be trapped is either encapsulated during the sealing process or later placed in the cavity by use of a fill hole. Typically, a resistor pattern is etched on the face of a pyrex wafer used as a top for the trench to form the cavity. When current is passed through this resistor, the material in the cavity is heated, its vapor pressure increases and expansion occurs. This causes the flexible wall to flex outward. This outward flex movement may then be used to either shut off a fluid flow path, or be sensed in some manner when using the device as a transducer. Typically, a fluid passageway having a nozzle aperture surrounded by a sealing surface is photolithographically etched into a third wafer. This third wafer is then bonded to the first wafer such that the sealing surface is adjacent to the membrane such that when expansion in the cavity occurs, the membrane flexes until it contacts the sealing surface and shuts off fluid flow through the nozzle aperture.

Integrated, microminiature electric to fluidic valve

There is disclosed herein an apparatus for converting control signals of an electrical or optical nature or any other type of signal which may be converted to a change of temperature of a fixed volume of material trapped in a chamber to flexure of a membrane forming one wall of the chamber. Typically, the device is integrated onto a silicon wafer by anisotropically etching a trench into said wafer for enough that a thin wall of silicon remains as the bottom wall of the trench. In some embodiments, polyimide is used as the material for the membrane. The trench is then hermetically sealed in any one of a number of different ways and the material to be trapped is either encapsulated during the sealing process or later placed in the cavity by use of a fill hole. Typically, a resistor pattern is etched on the face of pyrex wafer used as a top for the trench to form the cavity. When current is passed through this resistor, the material in the cavity is heated, its vapor pressure increases and expansion occurs. There is also disclosed herein a pressure regulator and a flow regulator each of which are integrated on a single die using the valve structure disclosed herein.

Growing community of inventors

Los Altos Hills, CA, United States of America

Mark J Zdeblick