Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
2000-12-08
2002-04-23
Picardat, Kevin M. (Department: 2823)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S121000, C438S124000, C438S612000
Reexamination Certificate
active
06376277
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to semiconductor packaging, and more particularly to a package for a plurality of semiconductor dice, which are singulated into individual integrated circuits.
Generally, in semiconductor manufacturing, an individual semiconductor die is mounted to a substrate and then sealed by an encapsulant or by a molding operation. The sealed package protects the die from breakage, and hazardous environmental contaminants. In addition, the package provides a lead system for connecting the resulting integrated circuit to a plurality of other similar circuits on a printed circuit board in an electronic system.
The semiconductor die includes a non-active surface which is typically mounted to a die receiving area on the substrate, and an active surface which has circuitry formed thereon. The circuitry is electrically connected to the substrate by bond pads formed on the active surface to corresponding bond pads on the substrate.
The initial component of the package is the substrate, for example, a lead frame. Typically, a lead frame supports a plurality of dice for packaging, and provides the leads for the final semiconductor package. The lead frame may be formed from a metal sheet of material. During the packaging process, each semiconductor die is mounted to a die paddle of a die receiving area by an adhesive. The adhesive is typically formed between the non-active face of the semiconductor die and the top surface of the die paddle.
During the packaging process, the bond pads formed on the semiconductor die are electrically connected to the leads of the lead frame using bond wires. An encapsulating layer is then formed over a portion of or across the entire active surface of the semiconductor die to seal the die and lead frame in a final package. After the package is sealed, the semiconductor packages are singulated by, for example, a trim and form operation, and the leads are bent to a desired configuration.
Recent advances in semiconductor manufacturing have led to a demand for smaller devices which may perform more functions. Thus, more input/output connection have been formed onto the semiconductor die, thereby increasing circuit densities. Common methods for securing these circuits to the substrate are wirebonding and tape-automated bonding (TAB). In TAB, the metal tape leads are attached between the bond pads on the semiconductor die and the bond pads on the substrate. In wirebonding, a plurality of electrical connections are formed one at a time between a bond pad on the semiconductor die and a corresponding pad on the substrate.
Due to the increased demand for high input/output chips, the semiconductor dies are typically formed in an array. Known packaging techniques includes ball grid array, dual-in line, flat pack, and hermetic and plastic chip carrier.
As mentioned above, the semiconductor die are formed on a substrate. In ball grid array (BGA) and fine-pitched ball grid array (FBGA) packaging, the substrate is typically formed from an organic material such as bismaleimide triazine (BT) resin. The BT resin is usually supplied as a sheet of material, and a plurality of semiconductor dice are formed in an array on the sheet of material. Once the electrical connections are formed, the semiconductor is sealed by molding or encapsulation by, for example, a glob top.
When a molding operation is used, the entire top surface of the substrate, with the semiconductor dice mounted thereon, is covered with a mold compound. The dice are then singulated by a trim and form operation.
One drawback to this method is that the resulting package is complex to manufacture because the resulting packages must be singulated by a precision sawing operation to avoid damage to the semiconductor dice. Typically, a saw or jig is used. The pressure which results from the saw blade cutting the mold may, for example, damage the electrical connections formed on the semiconductor die.
SUMMARY OF THE INVENTION
In general, the invention is directed to a semiconductor package which includes a substrate having a plurality of dice mounted thereon. The substrate includes a plurality of grooves to allow the semiconductor dice to be easily detached from the substrate to form individual integrated circuits.
Accordingly, in one aspect, the package includes a substrate having a first surface and a second surface. A plurality of first grooves are formed on the first surface to form a plurality of segments in the substrate. A semiconductor die is mounted to a corresponding segment on the second surface. An encapsulant is formed over the semiconductor die, and forms a plurality of second grooves formed in the encapsulant to correspond to the plurality of first grooves. A plurality of break points are formed from the first and second grooves to separate the individual segments from the substrate.
Implementations of the invention include one or more of the following. The substrate is formed from ceramic. The encapsulant is formed from a bismaleimide triazine resin. The plurality of first and second grooves are formed at an angle. The package is one of a ball grid array and a fine-pitched ball grid array package. The plurality of semiconductor dice are electrically connected to the substrate.
In another aspect, the invention is directed to a method for singulating a semiconductor package which includes a substrate having a first surface and a second surface. A plurality of grooves are formed in the first surface of the substrate to separate the substrate into a plurality of segments. A semiconductor die is mounted to each of the plurality of segments. The method further includes forming an encapsulant on each of the segments, wherein the encapsulant has a plurality of second grooves corresponding to the plurality of first grooves. A plurality of break points are formed form the first and second grooves such that each of the plurality of segments of the substrate is separated at a corresponding break point.
Implementation of the method include the following. The segments may be separated from the substrate by a shearing or punching operation.
Other advantages and features of the present invention will become apparent from the following description, including the drawings and claims.
REFERENCES:
patent: 5420460 (1995-05-01), Massingill
patent: 5598096 (1997-01-01), Pham et al.
patent: 5608262 (1997-03-01), Degani et al.
patent: 5719440 (1998-02-01), Moden
patent: 5895967 (1999-04-01), Sterns et al.
Collins D. M.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Picardat Kevin M.
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