Adhesive wafers for die attach application

Details Adhesive wafers for die attach application Adhesive wafers for die attach application

2001-10-23

2003-09-16

Fahmy, Wael (Department: 2823)

Semiconductor device manufacturing: process

Packaging or treatment of packaged semiconductor

Making plural separate devices

C438S464000

Reexamination Certificate

active

06620651

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an adhesive and bonding method for use in the fabrication of semiconductor packages. It is particularly useful in fabricating Chip Scale and Stacked Die Packages.
BACKGROUND OF THE INVENTION
Chip Scale Packages (CSP) provide the advantages of light weight, small footprint, high density, and enhanced electrical performance in semiconductor packaging. A CSP that includes one or more integrated semiconductor chips stacked one onto another further enhances electrical performance, and reduces space and weight.
Semiconductors are mechanically and electrically connected to a substrate, which in turn is connected to other devices or an outside power source. The substrate can be rigid, such as a metal leadframe, a ceramic or a laminate, or it can be flexible, such as a polyimide tape.
One method of connecting a semiconductor to its substrate is known as wire-bonding, in which the semiconductor chip first is adhered to the substrate with a paste or film adhesive, and then the active terminals on the chip are bonded to active terminals on the substrate with a fine metal wire.
Historically, paste adhesives have been used more often than film adhesives. However, some CSPs are more successfully fabricated using film adhesives because the films can be more precisely fitted to the chip configuration (x-y tolerance), there is minimal or no bleeding of adhesive, and bondline thickness and bondline tilt are more easily controlled.
However, the film process and equipment add cost and increase process time in producing chip scale and stacked chip scale packages. Semiconductor components are placed on their appropriate substrate using placement machines, commonly referred to as “pick-and-place” equipment. This equipment is important for placing components reliably and accurately enough to meet throughput requirements in a cost-efficient way.
In one method of fabricating a CSP using film adhesive, a decal is cut from the film, picked-up and placed onto the substrate, and laminated with pressure and heat. A semiconductor chip is then picked-up and placed onto the adhesive, and laminated to the adhesive with pressure and/or heat. In addition to the pick-and-place equipment, this method requires special film handling and laminating equipment.
In another method using a film adhesive, a decal is punched and laminated onto the substrate using pressure and/or heat, then a semiconductor chip is picked up and placed onto the adhesive and laminated to the adhesive with pressure and/or heat. This method requires a separate punch set for each shape of decal desired, and special punch and film laminating equipment.
Stacked chip CSPs can also be fabricated using the two methods and equipment above, although the required film materials may need to be different in thickness and exhibit different flow characterisitcs. The process for stacked chips entails picking-up and placing a decal of the film adhesive on the substrate, applying heat and pressure, picking-up and placing the die onto the adhesive, and applying heat and pressure. The process is repeated, but in this instance the decal of adhesive is placed on top of the first (mother) chip and laminated, followed by placement of a second (daughter) chip of the same or different geometry onto the mother chip. The daughter chip is then laminated. Typically, special film laminating equipment may be required for both mother and daughter chip placement and lamination.
In another method, an adhesive film is laminated directly to the backside of the semiconductor wafer, which is then diced into individual dies (singulation) using typical wafer dicing equipment. The adhesive remains laminated to the individual die and the die is now picked up and placed onto the substrate, or another die in the case of die stacking. The die is laminated to the substrate or first die with pressure and/or heat. This method requires special film laminating equipment as well as special film die bonding equipment.
Despite the advantages of film adhesive for CSPs and stacked chip CSPs, there is a relatively significant sector of the semiconductor packaging industry that prefers the process and equipment used for the application of paste adhesives, due to the lower cost, ease of use, and availability of this equipment within the industry.
Standard pick and place equipment for using paste adhesive to bond a semiconductor chip to a substrate first dispenses a paste adhesive onto a substrate, then picks-up a chip and places the chip onto the adhesive. The placement stage on which the substrate rests during placement may or may not be heated, but pressure applied by the pick and place tool can be used to optimize the quality of the die attach. This type of equipment normally does not possess post lamination capability and currently is less expensive than the equipment needed for using film.
The potential for using the pick-and-place, heating, and pressure components of this type of equipment to produce semiconductor packages, either with a single chip or stacked chips, with film adhesives would be an advantage in time and cost. The expensive punch sets and laminating components are avoided, and the operation itself takes less time. Moreover, a typical semiconductor packaging process requires wafer dicing capabilities, and with the proper choice of physical properties in a film, the dicing equipment could be used to dice the film adhesive into the appropriate configuration.
SUMMARY OF THE INVENTION
It has now been found that fabrication of a CSP or a stacked chip CSP can be accomplished with an unsupported film adhesive or an adhesive supported on a rigid carrier, using standard die attach equipment constructed for use with a paste adhesive. This invention is a method for fabricating a semiconductor using an unsupported film adhesive or an adhesive supported on a rigid carrier.


REFERENCES:
patent: 4199645 (1980-04-01), Schwarz
patent: 4874721 (1989-10-01), Kimura et al.
patent: 5286679 (1994-02-01), Farnworth et al.
patent: 5323060 (1994-06-01), Fogal et al.
patent: 5411921 (1995-05-01), Negoro
patent: 5548160 (1996-08-01), Corbett et al.
patent: 5564181 (1996-10-01), Dineen et al.
patent: 5600183 (1997-02-01), Gates, Jr.
patent: 5656551 (1997-08-01), Corbett et al.
patent: 5776799 (1998-07-01), Song et al.
patent: 5945733 (1999-08-01), Corbett et al.
patent: 5960260 (1999-09-01), Umehara et al.
patent: 6046072 (2000-04-01), Matsuura et al.
patent: 6124151 (2000-09-01), Jiang et al.
patent: 6175149 (2001-01-01), Akram
patent: 6175162 (2001-01-01), Kao et al.
patent: 6212767 (2001-04-01), Tandy
patent: 6228687 (2001-05-01), Akram et al.
patent: 6514795 (2003-02-01), Jiang et al.
patent: 0979852 (2000-02-01), None
patent: WO 93/23982 (1993-11-01), None
patent: WO 94/15358 (1994-07-01), None
patent: WO 96/32246 (1996-10-01), None
patent: WO 99/48140 (1999-09-01), None
patent: WO 00/77116 (2000-12-01), None
patent: WO 01/39266 (2001-05-01), None

Affiliated with

Also associated with

Rating

Adhesive wafers for die attach application does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Adhesive wafers for die attach application, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adhesive wafers for die attach application will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3071403