Lsi Logic Corporation

John Pierre McCormick

Kishor V Desai

Sunil A Patel

Brian J Lynch

Emily Hawthorne

Maniam B Alagaratnam

Kurt Raymond Raab

Michael D Rostoker

Jon M Long

Kumar Nagarajan

Ivor G Barber

Sarathy Rajagopalan

A method of assembling at least a first integrated circuit and a second integrated circuit into a multi chip module. The first integrated circuit is attached and electrically connected to a first substrate to form a first assembly, which is tested to ensure that it functions properly. The second integrated circuit is attached and electrically connected to a second substrate to form a second assembly, which is also tested to ensure that it functions properly. The first assembly is attached and electrically connected to the second assembly to form the multi chip module.

Multi chip module assembly

An integrated circuit having electrically conductive vias with a diameter of between about one micron and about fifty microns. Prior art vias have a diameter of between no less than 0.3 microns to no more than 0.8 microns. In this manner, stresses such as those that press down upon the top surface of the integrated circuit can be absorbed by the large vias and transferred past fragile layers, such as low k layers, so that the fragile layers are not damaged by the stresses.

Via construction for structural support

A method of forming an electrical contact on a surface of a substrate. A first layer of a first electrically conductive material is formed on the surface of the substrate, where the first layer is formed in a substantially contiguous sheet across the surface of the substrate. A non electrically conductive masking layer is applied to the first layer, where the masking layer leaves exposed first portions of the first layer and covers second portions of the first layer. The substrate is immersed in a first electrolytic plating bath, and a first electrical potential is applied between the first layer and the first electrolytic plating bath, thereby causing the formation of a second layer of a second electrically conductive material on the exposed first portions of the first layer. The substrate is immersed in a second electrolytic plating bath, and a second electrical potential is applied between the first layer and the second electrolytic plating bath, thereby causing the formation of a third layer of a third electrically conductive material on the second layer. The masking layer is removed from the substrate to expose the second portions of the first layer, and the exposed second portions of the first layer are removed to form discrete contact pads from the first portions of the first layer and the overlying second layer and third layer.

Method of forming electrolytic contact pads including layers of copper, nickel, and gold

A method for providing under bump metallization on a substrate. Trenches are formed in the substrate, and a layer of first electrically conductive material is formed over the substrate. The layer of the first electrically conductive material substantially fills the trenches and substantially covers the substrate between the trenches in a contiguous sheet. The layer of the first electrically conductive material is thinned to an end point where the layer of the first electrically conductive material is substantially reduced in thickness, but still forms the contiguous sheet between the trenches. A layer of photoresist is applied over the layer of the first electrically conductive material to define openings. A second electrically conductive material is deposited into the openings. The photoresist layer is removed, and the layer of the first electrically conductive material in the contiguous sheet between the trenches is removed to isolate the first electrically conductive material in the trenches. Because the layer of the first electrically conductive material is not completely removed in the areas between the trenches, the first electrically conductive material may be used as an electrode for the electroplate deposition of the second electrically conductive material. Thus, the under bump metallization can be produced in a more economical manner. If the layer of the first electrically conductive material were to be thinned to the point where the first electrically conductive material was only left in the trenches, then it would not be feasible to used the layer of the first electrically conductive material as an electrode, and thus it would further not be feasible to electroplate the second electrically conductive material.

Bonding pad interface

Provided is a vertically integrated (&ldquo;chip-over-chip&rdquo;) semiconductor package and packaging method. The invention provides higher packaging density and performance, including increased functionality, decreased signal propagation delays, improved circuit switching speed, lower thermal resistance and higher thermal dissipation measurements, relative to previous package designs. According to the invention, a semiconductor package may be composed of a flip chip (or chips) overlying one or more other flip chips, all electrically bonded to flip chip bond pads on a cavity-less semiconductor substrate. The upper and lower flips chips may be assembled in a variety of different configurations and may be thermally or electrically connected to each other. In a preferred embodiment, the flip chips, particularly the lower flip chip(s), are thinned so that the overall package height is within conventional ranges for traditional single chip packages. Packages in accordance with the invention have increased access speeds between chips and reduced total chip package footprint.

Chip-over-chip integrated circuit package

A solder mask is placed on a substrate but this solder mask is used to control solder spread but merely helps to protect traces that are distant from the bond pads. The solder mask has an opening that is preferably greater than the area of a die to be attached; this opening exposes both the bond pads and at least portions of traces proximate to the bond pads. The portions of the traces that are proximate to the bond pads are oxidized, thereby preventing solder from flowing onto these portions of the traces during the solder reflow process.

Method for attaching solderballs by selectively oxidizing traces

Vertically integrated flip chip semiconductor package

Provided is a two-step, dual-thickness solder mask material on the substrate surface. The material is preferably applied in a series of screenings: A first screening of the solder mask material in the region where the chip will be placed, and a second screening of solder mask surrounding the place on the substrate surface where the die will be placed, normally over the outside edge regions of the substrate surface. The thickness of this first screening of solder mask may be from about 10 to 20 microns, while the thickness of the second screening of solder mask is about conventional thickness for a solder mask, for example from about 30 to 40 microns.

Dual-thickness solder mask in integrated circuit package

One or two, or more, additional conductive layers, separated from one another (if two or more) and separated from a patterned (signal) conductive layer are formed in a flexible substrate, for mounting a semiconductor die in a semiconductor device assembly. These additional layers are used as separate planes for carrying power and/or ground from outside the assembly to the die, on a separate plane from signals entering or exiting the die. TAB processes are disclosed for cutting, bending and bonding inner and outer portions of selected signal layer traces to respective inner and outer edge portions of the additional conductive layer(s), including a two-stage process of (1) first cutting, bending and tacking the selected traces to the additional layer(s), and then (2) repositioning a bonding tool and securely bonding the selected traces to the additional layer(s). A tool (die pedestal) for aiding in the assembly process is also disclosed.

Multi-layer tab tape having distinct signal, power and ground planes, semiconductor device assembly employing same, apparatus for and method of assembling same

Provided is a die clip for use in semiconductor flip chip packaging as a replacement for the conventional combination of a heat spreader and stiffener, a packaging method using the die clip, and a semiconductor package incorporating the die clip. In a preferred embodiment, the die clip is a piece of high modulus, high thermal conductivity material shaped to attach over a die on the surface of a packaging substrate. The die clip closely engages the die while leaving some space open around the perimeter to provide access to the die. An underfill material may then be dispensed into the gap between the die and the substrate through an opening in the die clip. The underfill material is then cured, the die clip providing a heat sink and keeping the die and substrate flat and immobile during and after the curing process. A BGA process may then be used to apply solder balls to the underside of the substrate for subsequent bonding of the package to a circuit board for use.

Die clip assembly for semiconductor package

An electronic system such as a Board-Level-Product (BLP) includes at least one integrated circuit device which is mounted on a circuit board. Each integrated circuit device includes a thin dielectric substrate bearing a plurality of conductive leads and has a hole circumscribed by the substrate in which is positioned a die having pads that are bonded to ends of leads carried by the substrate and projecting into the hole for contact with the die pads. The leads include free outer ends that project laterally outwardly and downwardly away from the plane of the substrate for connection to contact pads on the circuit board. The free leads are isolated from pressure applied to the chip on tape assembly after it has been connected to a circuit board by means of a thin self-supporting thermally conductive heat spreader that contacts the side of the die opposite its pads and includes fixed standoff and/or alignment pins that extend through alignment holes in the thin substrate and are in physical contact with a surface of the printed circuit board. The arrangement enables transfer of force applied to the heat spreader directly to the circuit board, thereby isolating the die, thin substrate and its fragile free leads from forces applied to the die and/or the heat spreader.

Electronic system including packaged integrated circuits with heat

Provided is a multi-piece integrated heat spreader/stiffener assembly which is bonded to the substrate and die in a semiconductor package following electrical bonding of the die to the substrate, a packaging method using the integrated heat spreader/stiffener, and a semiconductor package incorporating the integrated heat spreader/stiffener. In a preferred embodiment, the integrated heat spreader/stiffener assembly has two pieces, both composed of a high modulus, high thermal conductivity material shaped to attach to each other and a die on the surface of a packaging substrate. A first piece of this assembly is bonded to the substrate surface adjacent to an electrically connected die and to the top surface of the die prior to the dispensation and curing of underfill material which provides the mechanical connection between the die and the substrate. With the first piece of the assembly in place, access may still be had to at least one edge of the die to dispense and cure the underfill epoxy. Once the underfill material is cured by heating, the second piece of the assembly is placed and bonded on the substrate either abutting or overlapping with the first piece. A ball grid array (BGA) process may then be used to apply solder balls to the underside of the substrate for subsequent bonding of the package to a circuit board for use.

Integrated heat spreader/stiffener assembly and method of assembly for

Provided is a single-piece integrated heat spreader/stiffener which is bonded to the substrate and die in a semiconductor package following electrical bonding of the die to the substrate, a packaging method using the integrated heat spreader/stiffener, and a semiconductor package incorporating the integrated heat spreader/stiffener. In a preferred embodiment, the integrated heat spreader/stiffener is a piece of high modulus, high thermal conductivity material shaped to attach over a die on the surface of a packaging substrate. The heat spreader/stiffener is equipped with a plurality of apertures to provide access to the top surface of the die for adhesive to bond the heat spreader/stiffener to the die, and to its perimeter to provide access for dispensation of underfill material between the die and the substrate. Once the adhesive and underfill materials are in place, the adhesive and underfill resins are cured by heating. A ball grid array (BGA) process may then be used to apply solder balls to the underside of the substrate for subsequent bonding of the package to a circuit board for use.

Integrated heat spreader/stiffener with apertures for semiconductor

A thin dielectric substrate bearing a plurality of conductive leads has a hole circumscribed by the substrate in which is positioned a die having pads that are bonded to ends of leads carried by the substrate and projecting into the hole for contact with the die pads. The leads include free outer ends that project laterally outwardly and downwardly away from the plane of the substrate for connection to contact pads on a circuit board. The free leads are isolated from pressure applied to the chip on tape assembly after it has been connected to a circuit board by means of a thin self-supporting thermally conductive heat spreader that contacts the side of the die opposite its pads and includes fixed standoff and/or alignment pins that extend through alignment holes in the thin substrate and are in physical contact with a surf ace of the printed circuit board. The arrangement enables transfer of force applied to the heat spreader directly to the circuit board, thereby isolating the die, thin substrate and its fragile free leads from forces applied to the die and/or the heat spreader.

Support assembly for mounting an integrated circuit package on a surface

Separate and distinct conductive layers for power and ground are insulated from one another and a patterned signal conductive layer to form a flexible substrate for mounting a semiconductor die in a semiconductor device assembly. TAB technology is utilized to produce an assembly that has superior electrical characteristics because power and ground is conducted on separate low impedance conductive layers. The power and ground leads connecting the semiconductor die and external circuits are selected from the signal trace layer, cut bent downward and attached by bonding to the respective power or ground layer. A tool is disclosed for cutting the selected leads. A method of attaching solder balls to a TBGA film using solder flux and photoimageable solder resist definition is also disclosed.

Growing community of inventors

Palo Alto, CA, United States of America

John Pierre McCormick