Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Making plural separate devices
Reexamination Certificate
1999-04-13
2001-03-20
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Making plural separate devices
C438S118000, C438S460000, C438S464000, C438S976000
Reexamination Certificate
active
06204092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to semiconductor processing, and more particularly to a method and apparatus for transferring a semiconductor die from an adhesive film hoop assembly to an output carrier pack.
2. Description of the Related Art
Semiconductor dies are typically manufactured by depositing on a wafer of material, such as silicon dioxide or gallium arsenide, a plurality of different layers of conductive, semiconductive and dielectric materials in precisely defined configurations. When the wafers are completed they are diced into individual dies, which are often very delicate. The individual semiconductor dies are difficult to handle during assembly of electronic apparatus because of their relatively small size and because certain types of semiconductor dies, such as laser diodes, are extremely fragile and thus easily damaged. A laser bar, also referred to as a bar of diodes, is formed by cleaving a section from a larger wafer on an adhesive film stretched over a hoop assembly. The wafer has a number of contiguous diodes, called the active strip, in a common substrate. The surface of the substrate in which the active strip is located is typically referred to as the p-side of the substrate. Typically, bonding pads, formed from a material such as gold, are formed on a surface of the semiconductor die to allow for connection of the semiconductor die to additional circuitry.
After the dies have been separated, they are placed on a die attach pad for bonding in an integrated circuit (IC) package or placed in a carrier for further packaging. This process is typically performed by a device known as a pick and place device. Each die is lifted by a collet and placed on a die attach pad or in a carrier. Die collets for placement of semiconductor dies are well known in the art.
FIG. 1
illustrates a typical commercially available pick and place device
10
. Device
10
may include a microscope
12
, an adjustable work platform
14
, and a control arm
16
. A collet
20
is secured at the end of the control arm which is designed to hold a semiconductor die (not shown) in position for die bonding or placement in a carrier or mounting member
18
positioned on the adjustable work platform
14
.
FIG. 2
illustrates a conventional technique for transferring a semiconductor die from an adhesive film to a carrier which may be used by pick and place device
10
of FIG.
1
.
A plurality of dies
40
, usually rectangular in shape, are processed on a layer of adhesive film
32
by any technique as is known in the art. Adhesive film
32
is typically secured at its edges by clamps
34
as illustrated in FIG.
2
. Disposed beneath adhesive film
32
is an expansion frame, such as for example a hoop frame
36
, movable in the direction of arrow
38
such that expansion frame
36
pushes upward on film
32
distending it vertically and stretching it horizontally, providing a tense, flat surface on which the semiconductor dies
40
reside.
For placement of each die
40
on a die attach pad of an integrated circuit (IC) or in a carrier for further packaging, each die
40
is lifted from film
32
by collet
20
of pick and place device
10
. Collet
20
has an aperture
46
at its distal end and a vacuum hole
48
extending through the length of collet
20
through which a vacuum pressure is exerted for lifting die
40
. A die
40
is lifted by collet
20
by positioning aperture
46
over a die
20
, exerting a vacuum pressure in the direction of arrow
52
and simultaneously moving an ejector pin
54
upwardly against the lower surface of film
32
. Ejector pin
54
assists collet
20
in removing die
40
from adhesive film
32
. Collet
20
is then moved upwardly away from film
32
by control arm
16
and positioned in another location for depositing the die
40
into another carrier (not shown), typically a pocket within a flat pack IC package.
There are problems, however, with the conventional pick and place operation as described with respect to FIG.
2
. For example, the removal of die
40
from film
32
by collet
20
and placement into a carrier requires that the control arm
16
move very precisely and at high speeds to ensure that the die
40
are not damaged and the throughput maintained. Additionally, the manufacturing process of die
40
allows only for the p-side to be up, i.e., the p-side can only be formed on the surface
41
of die
40
facing toward the collet
20
. It is preferable, for alignment purposes of the laser with external optics and also for thermal dissipation of the die
40
, to mount the die
40
p-side down in the end circuit. Thus, the die
40
, which is placed in an output carrier p-side up after being removed from film
32
, must be re-oriented p-side down in another carrier before bonding in the end circuit. Currently this process is done using a mechanical flipping operation that is cumbersome and operator intensive, resulting in further risk of damaging the die
40
and increased production costs.
Thus, there exists a need for an apparatus and method for transferring a semiconductor die from an adhesive film to an output carrier that eliminates the control arm/vacuum collet assembly and associated handling steps and orients the die p-side down into the output carrier.
SUMMARY OF THE INVENTION
The present invention overcomes the problems associated with the prior art and provides an apparatus and method for transferring a semiconductor die from an adhesive to an output carrier that eliminates the control arm/vacuum collet assembly and associated handling steps, while orienting the die p-side down into the output carrier.
In accordance with a preferred embodiment of the present invention, the adhesive film on which the die are secured is inverted so that the die face downward, p-side down, from the film. An output pack pocket is positioned beneath the die, and an ejector pin is pushed down from the top of the film to release the die. A vacuum is provided through a port in the pocket, pulling the released die into the port. Thus, the transfer occurs in a single step and orients the die p-side down in the output pack, eliminating the control arm/vacuum collet assembly and associated handling steps of conventional transfer mechanisms.
These and other advantages and features of the invention will become apparent from the following detailed description of the invention which is provided in connection with the accompanying drawings, in which like items are referred to by like numerals.
REFERENCES:
patent: 3887996 (1975-06-01), Hartleroad et al.
patent: 4667402 (1987-05-01), Wilde
patent: 4859269 (1989-08-01), Nishiguchi
patent: 5105255 (1992-04-01), Shannon et al.
patent: 5415331 (1995-05-01), Lin
Freund Joseph M.
Przybylek George J.
Romero Dennis M.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Lucent Technologies - Inc.
Niebling John F.
Zarneke David A.
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