Method and system for removing a die from a semiconductor...

Details Method and system for removing a die from a semiconductor... Method and system for removing a die from a semiconductor...

2000-02-22

2001-10-30

Bowers, Charles (Department: 2813)

Semiconductor device manufacturing: process

With measuring or testing

Packaging or treatment of packaged semiconductor

C438S004000, C438S014000

Reexamination Certificate

active

06309899

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to semiconductor devices, and more particularly to a method and system for more easily removing a die from a semiconductor device including a ceramic base.
BACKGROUND OF THE INVENTION
FIG. 1
depicts a current semiconductor package
10
. The semiconductor package
10
is a flip-chip package. The semiconductor package
10
includes a semiconductor die
12
on a ceramic base
14
. The semiconductor package
10
is termed a flip-chip package because the top face of the die
10
is facing the ceramic base
14
. Thus, contact is made to circuits within the die
12
through solder bumps
16
. An underfill
18
is also included in the semiconductor package
10
and aids in bonding the die
12
to the ceramic base
14
. The ceramic base
14
typically has a layer of metal
15
close to the top surface of the ceramic base
14
. The ceramic base
14
is coupled to pins
19
which allow the die
12
to be electrically coupled to an outside circuit (not shown).
Although the semiconductor package
10
function when formed properly, current processing methods for semiconductor packages
10
typically does not result in all dies
12
functioning as desired. It is relatively simple to determine the failure mode, such as whether there is a short in a circuit within the die
12
or whether a particular voltage is being output. However, in order to determine the failure mechanism, the location and nature of the fault, the die
12
must be removed from the semiconductor package
10
. In particular, the die
12
must be separated from the ceramic base
14
. The die
12
can then be deprocessed and the failure mechanism determined.
FIGS. 2A and 2B
depict a conventional system
20
and method
30
for removing the die
12
from the semiconductor package
10
. Referring to
FIGS. 2A and 2B
, the die
12
is thinned, typically to between fifty and eighty microns, and a second die
22
is glued to the thinned die
12
, via step
32
. The second die
22
is typically a piece of silicon without any circuitry and of approximately the same size as the die
12
. Generally, the ceramic base
14
is also trimmed to a certain extent. The combination of the thinned die
12
, the second die
22
and the ceramic base
14
is then encapsulated in resin
24
, via step
34
.
FIG. 2A
depicts the thinned die
12
, the ceramic base
14
and the second die
22
after being encapsulated in the resin
24
. Typically, the encapsulation step
34
is carried out so that the ceramic base
14
is exposed. For example, the thinned die
12
, the ceramic base
14
and the second die
22
may be placed in a mold with the ceramic base
14
down. The mold is then filled with resin and, after the resin has cured, removed from the mold. The ceramic base
14
is then ground until the die
12
has been exposed, via step
36
. Typically, the grinding step is accomplished by mechanically grinding the ceramic base, and any resin
24
surrounding the ceramic base
14
.
Although the method
30
functions, one of ordinary skill in the art will readily recognize that the die
12
typically cannot be removed from the resin
24
. Currently, no known solvent will etch the resin
24
without damaging the die
12
. Consequently, although the die
12
can be separated from the ceramic base
14
, the die
12
cannot be easily deprocessed. Consequently, it is difficult, if not impossible, to determine a failure mechanism for the die
12
when the method
30
is used.
FIGS. 3A and 3B
depict another conventional system
40
and method
50
for removing a die
12
from the semiconductor package
10
. The die
12
is thinned and, if desired, glued to a second die (not shown), via step
52
. The die
12
and ceramic base
14
are then fixed in a sample holder using a soft wax, via step
54
.
FIG. 3A
depicts a sample holder
42
and the soft wax
44
which holds the die
12
and ceramic
14
in place. The soft wax
44
is typically somewhat pliable at room temperature. Note that the sample holder
42
need not have a recess which contains the soft wax
44
, die
12
and ceramic base
14
. Instead, the sample holder
42
may simply have a planar surface. The soft wax then simply affixes the die
12
and ceramic base
14
to the planar surface of the sample holder
42
. The ceramic base
14
is then ground away to expose the die
12
, via step
56
. Typically, the ceramic base
14
is mechanically ground. The die
12
is then removed from the soft wax
44
, by heating up the sample holder
42
and melting the soft wax
44
.
Although the method
50
may separate the die
12
from the ceramic base
14
, one of ordinary skill in the art will readily recognize that the method
50
is subject to failure. In particular, the die
12
often breaks during grinding of the ceramic base
14
. For example, when the ceramic base
14
becomes very thin, the layer of metal
15
within the ceramic base
14
often fractures, breaking the remainder of the ceramic base
14
and the die
12
. Furthermore, grinding heats the die
12
and ceramic base
14
. As a result, the soft wax
44
softens further. This allows the die
12
and ceramic base
14
to move within the sample holder
42
during grinding. Consequently, the ceramic base
14
and die
12
are subject to breakage. Once the die
12
breaks, it becomes difficult if not impossible to deprocess the die
12
. Consequently, failure mechanisms within the die
12
cannot be determined.
Accordingly, what is needed is a system and method for removing a semiconductor die from a semiconductor package. The present invention addresses such a need.
SUMMARY OF THE INVENTION
A method and system for removing a die from a semiconductor package is disclosed. The semiconductor package includes the die and a ceramic base. The die has a first face, a second face and a plurality of sides. The second face of the die is coupled with the ceramic base. The method and system comprise covering at least the first face and a portion of the plurality of sides of the die with a hard wax and encapsulating the hard wax and at least a first portion of the ceramic base in a resin. The method and system also comprise removing at least a second portion of the ceramic base to expose the second face of the die and removing the hard wax to free the die.
According to the system and method disclosed herein, the present invention provides a simple method for removing a die from a semiconductor package. Moreover, the method is the only known procedure for removing a thin die from a package.


REFERENCES:
patent: 5240546 (1993-08-01), Shiga
patent: 5344795 (1994-09-01), Hashemi et al.
patent: 5946556 (1999-08-01), Hashizume
patent: 5976897 (1999-11-01), Gomez
patent: 6030282 (2000-02-01), Mahanpour
patent: 6127194 (2000-10-01), Mahanpour et al.

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