National Semiconductor Corporation

National Semiconductor Corporated

Shahram Mostafazadeh

Joseph O Smith

Satya N Chillara

Viraj Ajit Patwardhan

Luu Thanh Nguyen

Hau Thanh Nguyen

Jagdish G Belani

Gerald Alexander Fields

Hem P Takiar

Peter B Johnson

Nikhil Vishwanath Kelkar

Steven J Adler

Gokhan Percin

Matthew Douglas Penry

Nikhil K Kelkar

Ethan Warner

A method for forming a capacitive micromachined ultrasonic transducer (CMUT) includes forming multiple CMUT elements in a first semiconductor-on-insulator (SOI) structure. Each CMUT element includes multiple CMUT cells. The first SOI structure includes a first handle wafer, a first buried layer, and a first active layer. The method also includes forming a membrane over the CMUT elements and forming electrical contacts through the first handle wafer and the first buried layer. The electrical contacts are in electrical connection with the CMUT elements. The membrane could be formed by bonding a second SOI structure to the first SOI structure, where the second SOI structure includes a second handle wafer, a second buried layer, and a second active layer. The second handle wafer and the second buried layer can be removed, and the membrane includes the second active layer.

Integration of structurally-stable isolated capacitive micromachined ultrasonic transducer (CMUT) array cells and array elements

Improved protective metallization is described for bumped copper-top semiconductor chips. The semiconductor device includes a top wafer fabrication passivation layer with openings through which contact pads are exposed. A patterned copper layer is formed over the passivation layer and is electrically coupled to the contact pads through the openings. A metallic barrier layer is provided between the contact pads and the patterned copper layer. A titanium metallization layer overlies the patterned copper layer and cooperates with the barrier layer to envelop the copper layer in the regions of the contact pads. An aluminum metallization layer overlies the titanium metallization layer. An electrically insulating protective layer overlies the aluminum metallization and passivation layers. The protective layer includes openings in which underbump metallization stacks are formed. Each underbump metallization stack electrically connects to the aluminum metallization layer through an opening in the protective layer. Solder bumps adhere to the underbump metallization stacks.

Metallurgy for copper plated wafers

A micro surface mount die package is described that includes a die attach pad having a plurality of integrally formed risers. A bumped die is mounted on the die attach pad such that the risers are located to the side of the die and the contact bumps face away from the die attach pad. An encapsulant covers the active and side surfaces of the die while leaving the contact bumps exposed on the packaged semiconductor device. Methods for forming such packages and panels suitable for use in forming such packages are also described.

Micro surface mount die package and method

The invention includes a die-level opto-electronic device with a semiconductor die and a photonic device including a conductive structure formed in the die away from the edges of the die. The conductive structure is electrically connected to the photonic device. The device also includes an optically transparent laminate attached to overlay the photonic device. The invention also comprises a semiconductor wafer with a plurality of photonic devices exposed on a first surface and a plurality of conductive structures being exposed on a second surface opposing the first surface. The conductive structures are electrically connected to the photonic devices which are overlaid with an optically transparent laminate. The invention further includes methods of forming die-level opto-electronic devices and semiconductor wafers.

Die-level opto-electronic device and method of making same

An apparatus and method for increasing integrated circuit device package reliability is disclosed. According to one embodiment of the present invention, a support coating is added to a wafer after solder bumps have been added but prior to dicing. This support coating or underfill layer provides added strength to the eventual reflowed solder connections, such that the operational lifetime of these connections is increased with respect to failure due to temperature cycling.

Integrated circuit device package having a support coating for improved reliability during temperature cycling

Packages of semiconductor devices with non-opaque covers and methods for making the packages. The invention allows an encapsulant to be used with a non-opaque cover. By ensuring the cover is attached to a die in such a way as to expose bonding pads while sealing in the imaging portion of the die, the die can be electrically connected to a substrate and then encapsulated. Since the imaging portion is sealed, the encapsulant cannot get underneath the glass. By ensuring the encapsulant is not filled beyond the glass, encapsulant cannot get over the glass either.

Packaging of a semiconductor device with a non-opaque cover

Arrangements and methods of packaging integrated circuits in leadless leadframe packages configured for maximizing a die size are disclosed. The package is described having an exposed die attach pad and a plurality of exposed contacts formed from a common substrate material. The contacts, however, are thinned relative to the die attach pad. In one embodiment, an inner region of the contacts is thinned. In another embodiment, an outer region of the contacts is also thinned. A die is mounted on the die attach pad and wire bonded to the contacts. Since the inner region and sometimes together with the outer region of the contact are lower than the die attach pad being wire bonded to, the size of the die can be relatively increased to overhang over the contact, thereby maximizing the die size in the package. A plastic cap is molded over the die, contacts, and bonding wires while leaving the bottom surface of the contacts exposed.

Leadless microelectronic package and a method to maximize the die size in the package

A method for producing chip scale IC packages includes the step of mounting a lead frame panel on a temporary support fixture in order to provide support and protection during the manufacturing process. An embodiment of the temporary support fixture includes a sheet of sticky tape secured to a rigid frame. The rigid frame maintains tension in the sheet of sticky tape to provide a stable surface to which the lead frame panel can be affixed. Installation of IC chips and encapsulation in protective casings is performed as in conventional IC package manufacturing. If encapsulant material is to be dispensed over the IC chips, an encapsulant dam can be formed around the lead frame panel to contain the flow of encapsulant material. The temporary support fixture can be used in any IC package manufacturing process in which lead frames require supplemental support.

Lead frame chip scale package

An apparatus and method for forming a layer of underfill adhesive on an integrated circuit in wafer form is described. In one embodiment, the layer of underfill adhesive is disposed and partially cured on the active surface of the wafer. Once the underfill adhesive has partially cured, the wafer is singulated. The individual integrated circuits or die are then mounted onto a substrate such as a printed circuit board. When the solder balls of the integrated circuit are reflowed to form joints with corresponding contact pads on the substrate, the underfill adhesive reflows and is completely cured. In an alternative embodiment, the underfill adhesive is fully cured after it is disposed onto the active surface of the wafer.

Method and apparatus for forming an underfill adhesive layer

An apparatus and method for force mounting semiconductor packages onto printed circuit boards without the use of solder. The apparatus includes a substrate, a first integrated circuit die mounted onto the substrate, a housing configured to house the first integrated circuit die mounted onto the substrate, and a force mechanism configured to force mount the housing including the integrated circuit die and substrate onto a printed circuit board. The method includes mounting a first integrated circuit die onto a first surface of a substrate, housing the first integrated circuit die mounted onto the substrate in a housing, and using a force mechanism to force mount the housing including the first integrated circuit die mounted on the substrate onto a printed circuit board. According to various embodiments, the force mechanism includes one of the following types of force mechanisms clamps, screws, bolts, adhesives, epoxy, or Instrument housings or heat stakes.

Apparatus and method for force mounting semiconductor packages to printed circuit boards

Multichip packages and methods for making same. The present invention generally allows for either the back of a flipchip, the back of a mother die, or both to be exposed in a multichip package. When the mother die is connected to the package contacts, the back of the flip chip is higher than the electrical connections. Accordingly, the back of the flip chip can be exposed. Furthermore, if a temporary tape substrate is used with a leadframe panel that does not have a die attach pad, the package can be even thinner. Once the temporary tape substrate is removed, both the back of the flipchip and the back of the mother die will be exposed from the encapsulant.

Multichip packages with exposed dice

In one embodiment of the invention, a die-level opto-electronic device comprises a semiconductor die having edges and a photonic device exposed on a first surface. The device includes a conductive structure formed in the die and away from the edges of the die, the conductive structure being exposed on a second surface of the die that opposes the first surface, wherein the conductive structure is electrically connected to the photonic device. The device also includes an optically transparent laminate attached to the first surface so as to overlay the photonic device. In another embodiment of the invention, a semiconductor wafer comprises a substrate having a plurality of photonic devices exposed on a first surface. A plurality of conductive structures is formed in the substrate, the plurality of structures being exposed on a second surface of the substrate that opposes the first surface, wherein ones of the plurality of structures are electrically connected to associated ones of the plurality of photonic devices. An optically transparent laminate is attached to the first surface so as to overlay the plurality of photonic devices. Methods of forming the die-level opto-electronic devices and semiconductor wafers of the invention are also described.

Processes for packaging integrated circuits in microarray packages are described. In a method aspect of the invention, a first side of a metal sheet is etched to define a lead frame panel having a plurality of device areas. Each device area includes an array of contact posts suitable for forming contact pads and a plurality of lead traces. Each lead trace is coupled to an associated contact pad. The etching is arranged so that it does not etch all of the way through the metal sheet. Rather, the etching thins portions of the lead frame panel apart from the contact posts and lead traces to form a thin connecting sheet that holds the contact posts and lead traces in place. With this arrangement, the contact posts and lead traces defined in the resulting lead frame structure are held in place by the thin connecting sheet and are raised relative to the connecting sheet. The resulting etched leadframe panel is particularly well suited for use in microarray packages. In various embodiments, other lead frame structures may be incorporated into the device areas as desired.

Microarray lead frame

A variety of techniques and structures are described that integrate an insulated pedestal into the back surface of integrated circuit dice. The die has an insulated integral pedestal formed therein that acts as a spacer. The pedestal has a footprint that is smaller than the total footprint of the die so that a portion of the active region of the die overhangs the pedestal. The geometry of the pedestal may be widely varied and in some embodiments, multiple pedestals may be provided on the stacked die. In another aspect, the pedestals are formed at the wafer level such that the pedestals are defined in the back surface of the wafer. Often, the thickness of the pedestals will be thicker than the portions of the wafer outside the pedestal areas. The described dice are particularly well suited for use in stacked die packages.

Die with integral pedestal having insulated walls

An optical integrated circuit application where the integrated circuit is packaged in a clear molding material and is attached to a printed circuit board having an aperture is described. The integrated circuit senses and/or emits light through the clear molding material and through the aperture in the printed circuit board.

Growing community of inventors

San Jose, CA, United States of America

Shahram Mostafazadeh