Patent ID: 12237351

DESCRIPTION

This disclosure, its aspects and implementations, are not limited to the specific components, assembly procedures or method elements disclosed herein. Many additional components, assembly procedures and/or method elements known in the art consistent with the intended semiconductor package will become apparent for use with particular implementations from this disclosure. Accordingly, for example, although particular implementations are disclosed, such implementations and implementing components may comprise any shape, size, style, type, model, version, measurement, concentration, material, quantity, method element, step, and/or the like as is known in the art for such semiconductor packages, and implementing components and methods, consistent with the intended operation and methods.

Referring toFIG.1, an implementation of a semiconductor package2is illustrated. The package includes a substrate4having a first side6and a second side8. In various implementations, the substrate may be a stripline. In some implementations, the stripline substrate may have multiple units on it. In other implementations, the substrate may be a printed circuit board or other similar substrates. The package also includes a first side10of a die12coupled to the second side8of the substrate4through wire bonds14. In some implementations, the wire bonds may be gold wire. In various implementations, the die12is coupled to the substrate4through die bond adhesive such as, by non-limiting example, epoxies or polyimides. The die bond adhesive may be electrically conductive in various implementations, or may not be electrically conductive.

In implementations including a silicon die, the silicon substrate may include a photodiode array therein. In various implementations, the semiconductor die12includes a silicon layer. In other implementations, the semiconductor die12may include a substrate having silicon dioxide, glass, silicon-on-insulator, gallium arsenide, sapphire, ruby, silicon carbide, polycrystalline or amorphous forms of any of the foregoing, and any other type of substrate type for constructing image sensor or semiconductor devices.

The second side16of the die12includes an active area18. In various implementations, the die may be a contact image sensor (CIS) die. In an image sensor die, the active area18includes a contact layer. In various implementations, the contact layer may be considered part of the semiconductor die, or it may be considered separate from but coupled to the semiconductor die. As used herein, the contact layer is considered part of the semiconductor die and is not considered separate from the material of the semiconductor die. In various implementations, the contact layer may be an interlayer dielectric (LID) material. The contact layer may also include one or more metal layers therein. The metal layers may include one or more metal landing pads. In various implementations, the metal layers and/or metal landing pads may include aluminum, copper, tungsten, any other metal, and any combination or alloy thereof. In various implementations, the contact layer may include one or more diffusion barrier layers. In particular implementations, the one or more diffusion barrier layers may be adjacent to the backside/first surface, and/or the front side/second surface. The diffusion barrier layer may include SiN or any other material used in a diffusion barrier layer. The contact layer may include other elements therein, such as gates or other semiconductor elements.

A ball grid array15is coupled to a first side6of the substrate4. The ball grid array15may be formed of solder, gold, copper, nickel, lead, tin, or other suitable electrically conductive materials. In various implementations, other types of interconnects may be coupled to the first side of the substrate such as, by non-limiting example, pin grid array (PGA), land grid array, individual solder balls, gold studs, copper studs, and other interconnects that have good electrical conductive properties.

The package also includes two portions of molding compound20,22. An interface21is illustrated between the first molding compound and the second molding compound. The interface is illustrated in an enlarged form for ease of viewing and explanation, in actual devices the interface may not be readily visible. In some implementations, the interface may be roughened or patterned to aid in bonding of the first molding compound and the second molding compound. The two portions of molding compound may help to seal the glass. The first portion20of molding compound is formed on and over a portion of the substrate4and the die12. In various implementations, the molding compounds may include, by non-limiting example, epoxies, polymers, resins, or other mold compound types.

From the cross sectional view, the cushion24is illustrated as two cushions positioned between a first side26of a glass lid28and the first portion20of the molding compound. In a top view as illustrated inFIG.8, the cushion25is illustrated as a closed loop having a substantially rectangular shape. The cushion may be dispensed on the shelf of the first molding compound to support the lid and adhere to the glass. In some implementations, two cushions could be formed where the two cushions are concentric. In other implementations, more than two cushions may be used. In various implementations, the cushion may be positioned between the glass lid and the first portion of molding compound. The cushion may allow the release of thermal stress and improve reliability of the package. The cushions may also be referred to as dams. The dams may further increase the air and moisture seal of the die. The cushions/dams may be formed of, by non-limiting example, rubber, resin, epoxy, silicone, acrylic, polyimide, polymer, any combination thereof, or other resilient and moisture blocking materials. The second portion22of molding compound is coupled with an edge of the first portion of molding compound and over a portion of a second side30of the glass lid. Using a combination of molding compounds may decrease chances of delamination when compared with packages employing an adhesive to hold the glass lid over the die. Typical packaging for CIS use liquid adhesive to bond the glass lid on CIS die. Typical packages suffer from delamination on the interface between resin and glass or between resin and die when the thermal stress increases.

Referring toFIGS.2-7, an implementation of a method of forming a semiconductor package is illustrated. The method includes providing a substrate32as illustrated inFIG.2. The substrate may include a stripline structure. A stripline circuit uses a flat strip of metal coupled between two parallel group planes. The insulating material of the substrate forms a dielectric. In various implementations, the stripline may include multiple units on a single strip. In some implementations, the multiple units may be singulated before coupling die to the substrates. In other implementations, the multiple units may be singulated later in the process. In other implementations, the substrate may be a standard printed circuit board, laminated substrate, sintered substrate, or another substrate type.

Referring toFIG.3, the method includes coupling a first side34of a semiconductor die36to the second side38of the substrate40. The first side of the die34may be coupled through die adhesive such as epoxies or polyimides. In various implementations, the die may be made of silicon. In other implementations, the semiconductor die may include a substrate having silicon dioxide, glass, silicon-on-insulator, gallium arsenide, sapphire, ruby, silicon carbide, polycrystalline or amorphous forms of any of the foregoing, and any other type of substrate for constructing image sensor or semiconductor devices. The die36includes an active region42on the second side44of the die. The active region of the die may be a contact image sensor (CIS). In various implementations, the contact layer may be considered part of the semiconductor die, or it may be considered separate from but coupled to the semiconductor die. The die is electrically coupled to the substrate through two or more wire bonds42. In various implementations, the wire bonds may be gold wire or another suitable metal.

The die may be formed through various methods of processing semiconductor die after forming a plurality of semiconductor devices thereon. The die may each be separated by die streets in various implementations. The method may include thinning a backside of the die opposite the first side of the die. This may be done by thinning the wafer using any suitable method such as by non-limiting example, backgrinding, lapping, wet etching, any combination thereof, or any other technique for removing backside damage and/or the material of the semiconductor substrate substantially uniformly across the largest planar surface of the substrate. The method may also include flipping the wafer. The wafer may be coupled to a backgrinding tape and flipped using the tape. In other implementations, the wafer may be singulated into individual die and then the die may be flipped. The plurality of die may be singulated through lasering, sawing, plasma etching, or water jet ablating. Following singulation, the individual die may be coupled to a picking tape thereby making flipping easier. In other implementations, the die may be individually removed from the picking tape through a pick and place system and sorted into a carrier tape.

The die is then removed from the carrier tape and coupled with the substrate using any of the die attach materials disclosed in this document. Wire bonds are then applied to the die and substrate to make the needed electrical connections between the die and the substrate. However, in various implementations, electrical connectors other than wire bonds could be employed such as, by non-limiting example, bumps, pillars, through silicon vias, pads, clips, or other electrical connector types.

Referring toFIG.4, the method then includes forming a first portion48of molding compound over the substrate50and the die52. The first48molding compound may be formed to couple over a portion of the substrate50and around a portion of the die52. The first48molding compound does not contact the active area of the die. In various implementations, the first48molding compound may be formed to protect and encapsulate the wire bonds54coupling the die52to the substrate50. The first portion of molding compound may form a shelf56. The shelf56may form a platform for the glass lid to attach to as illustrated inFIG.6. The shelf may have a width A, which may be wider than width B of the second molding compound as illustrated inFIG.7. The differences in width of molding compound may facilitate formation of the second molding compound. The differences in width may also prevent cracking of a glass lid during pressure loading during the molding process. In various implementations, the first molding compound may be formed through transfer molding. In other implementations, the molding compound may be formed through other suitable molding processes.

Referring toFIG.5, the method also includes applying a flexible cushion/dam58to the shelf formed in the first molding compound62. The flexible cushion/dam58may be made of, by non-limiting example, rubber, epoxy, silicone, acrylic, resin, polyimide, polymer, any materials described herein, or any combination thereof. The flexible cushion/dam58may act as a buffer to thermal stress and prevent the delamination of the package. In various implementations, the modulus of the flexible dam may be very low in order to allow the coefficient of thermal expansion (CTE) to be variable.

Referring toFIG.6, the method further includes coupling a first side64of a glass lid66to the shelf68of the first molding compound. The glass lid66is coupled to the shelf68through/over the flexible cushion/dam72. The flexible property of cushion/dam72may also allow for changes in the gap height between the glass lid and the sensor in the active area of the die. The flexibility of the cushion/dam72may also help to keep the glass lid66in a planar position. In some implementations, the material of the flexible cushion72may be cured following placement of the lid over the cushion72. The flexible cushion may be cured by ambient environmental (activated by moisture) cure, thermal cure, or by ultraviolet light cure. In various implementations, the flexible cushion may have high stand off capability and may become a dam after having been cured.

Referring toFIG.7, the method may include forming a second molding compound74on an interface of the first molding compound76and a portion of the second side78of the glass lid80. As previously described, the interface between the first molding compound and the second molding compound is exaggerated inFIG.7to facilitate understanding of this feature. The second molding compound is also coupled around two or more edges82of the glass lid. The second molding compound may create a seal around the glass lid. In various implementations, the method may further include plasma cleaning the interface of the first molding compound before coupling of the second molding compound. Plasma cleaning may help form a stronger adhesive bond between the first molding compound and the second molding compound.

As previously described, the width of the shelf A may be larger than the width B of the second molding compound74covering a second side78of the glass lid80. The differences in width may also decrease problems in the manufacturing process. As previously mentioned, differences in width may prevent cracking of the glass lid during pressure loading of the molding process. The second molding compound has a flat surface on the side of the second molding compound opposing the first molding compound. In various implementations, the flat surface may be suitable to couple a lens holder to the second molding compound. The structure of the semiconductor packages like those disclosed in this document may provide a more flexible and compact size for a camera module design.

The method of forming a semiconductor package also includes coupling a ball grid array82to the first side86of the substrate84. In various implementations, other interconnects may be coupled to the first side of the substrate such as by non-limiting example land grid array (LGA), pin grid array (PGA), or individual interconnects. The interconnects may be coupled through soldering. In other implementations, the array of interconnects may be coupled through sockets. Individual interconnects may include bumps, studs, or pins formed of electrically conductive metals such as, by non-limiting example, gold, copper, silver, lead, tin, nickel or any combination thereof.

In places where the description above refers to particular implementations of semiconductor packages and implementing components, sub-components, methods and sub-methods, it should be readily apparent that a number of modifications may be made without departing from the spirit thereof and that these implementations, implementing components, sub-components, methods and sub-methods may be applied to other semiconductor packages.