U.S. patent application number 11/115236 was filed with the patent office on 2005-09-01 for semiconductor package.
This patent application is currently assigned to ADVANCED SEMICONDUCTOR ENGINEERING, INC.. Invention is credited to Chiu, Chi Tsung, Tao, Su, Wu, Sung Mao.
Application Number | 20050189641 11/115236 |
Document ID | / |
Family ID | 32391376 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050189641 |
Kind Code |
A1 |
Tao, Su ; et al. |
September 1, 2005 |
Semiconductor package
Abstract
A semiconductor package comprises a first chip, a substrate, a
middle layer, a second chip, and an encapsulant. The first chip has
an active surface and a high-frequency element defining a
high-frequency area on the active surface. The substrate supports
the first chip and is electrically connected to the first chip. The
middle layer is disposed on the first chip and has a recess
corresponding to the high-frequency area. The second chip is
disposed on the middle layer and electrically connected to either
the first chip or the substrate. The encapsulant encapsulates the
first chip, the middle layer, the second chip, and a part of the
substrate.
Inventors: |
Tao, Su; (Kaohsiung, TW)
; Chiu, Chi Tsung; (Kaohsiung, TW) ; Wu, Sung
Mao; (Kaohsiung, TW) |
Correspondence
Address: |
LOWE HAUPTMAN GILMAN AND BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300 /310
ALEXANDRIA
VA
22314
US
|
Assignee: |
ADVANCED SEMICONDUCTOR ENGINEERING,
INC.
Kaohsiung
TW
|
Family ID: |
32391376 |
Appl. No.: |
11/115236 |
Filed: |
April 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11115236 |
Apr 27, 2005 |
|
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10648363 |
Aug 27, 2003 |
|
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Current U.S.
Class: |
257/686 ;
257/E21.503; 257/E21.505; 257/E23.128; 257/E25.013 |
Current CPC
Class: |
H01L 2224/05599
20130101; H01L 2224/73203 20130101; H01L 2224/73265 20130101; H01L
2924/15311 20130101; H01L 24/83 20130101; H01L 2224/48091 20130101;
H01L 2224/48227 20130101; H01L 2224/48145 20130101; H01L 2924/0665
20130101; H01L 2924/19041 20130101; H01L 2224/85399 20130101; H01L
2924/15311 20130101; H01L 2924/181 20130101; H01L 2924/00014
20130101; H01L 2224/05599 20130101; H01L 2924/15311 20130101; H01L
2924/15311 20130101; H01L 2924/01087 20130101; H01L 2225/0651
20130101; H01L 2924/19042 20130101; H01L 2224/48091 20130101; H01L
2224/73265 20130101; H01L 24/48 20130101; H01L 2224/32225 20130101;
H01L 24/32 20130101; H01L 2224/73265 20130101; H01L 2224/73204
20130101; H01L 2924/014 20130101; H01L 2224/32145 20130101; H01L
23/315 20130101; H01L 2224/2919 20130101; H01L 2224/8385 20130101;
H01L 2224/73265 20130101; H01L 2225/06568 20130101; H01L 23/66
20130101; H01L 2224/45099 20130101; H01L 2224/2919 20130101; H01L
2924/01033 20130101; H01L 2224/73204 20130101; H01L 2924/01006
20130101; H01L 24/73 20130101; H01L 23/3128 20130101; H01L 21/563
20130101; H01L 2224/16225 20130101; H01L 2224/29011 20130101; H01L
2224/73265 20130101; H01L 25/0657 20130101; H01L 2924/181 20130101;
H01L 2924/0665 20130101; H01L 2224/8319 20130101; H01L 2924/19043
20130101; H01L 2225/06506 20130101; H01L 2224/85399 20130101; H01L
2224/45099 20130101; H01L 2924/01082 20130101; H01L 2224/73204
20130101; H01L 2224/48227 20130101; H01L 2924/0665 20130101; H01L
2924/00 20130101; H01L 2224/32225 20130101; H01L 2224/32225
20130101; H01L 2924/00014 20130101; H01L 2224/73265 20130101; H01L
2924/00014 20130101; H01L 2924/07802 20130101; H01L 2224/48227
20130101; H01L 2924/00 20130101; H01L 2924/00 20130101; H01L
2924/00012 20130101; H01L 2224/32225 20130101; H01L 2224/48227
20130101; H01L 2224/32225 20130101; H01L 2924/00 20130101; H01L
2924/00014 20130101; H01L 2224/16225 20130101; H01L 2224/45015
20130101; H01L 2224/73265 20130101; H01L 2924/00012 20130101; H01L
2924/00 20130101; H01L 2924/207 20130101; H01L 2224/32225 20130101;
H01L 2224/48145 20130101; H01L 2224/32225 20130101; H01L 2224/32145
20130101; H01L 2924/00012 20130101; H01L 2224/48227 20130101; H01L
2224/48227 20130101; H01L 2224/48145 20130101; H01L 2224/73265
20130101; H01L 2924/00 20130101; H01L 2924/00012 20130101; H01L
2924/00014 20130101; H01L 2224/16225 20130101; H01L 2224/48227
20130101; H01L 2224/32145 20130101; H01L 2924/00014 20130101; H01L
2224/32145 20130101; H01L 2224/32225 20130101 |
Class at
Publication: |
257/686 |
International
Class: |
H01L 023/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2002 |
TW |
091135502 |
Claims
1-11. (canceled)
12. A semiconductor package comprising: a chip defining an active
surface and having a high-frequency element defining a
high-frequency area on the active surface; a substrate supporting
the chip and electrically connected to the chip; an encapsulant
encapsulating the active surface of the chip, and a part of the
substrate; and a cavity positioned within the encapsulant above the
high-frequency area.
13. The semiconductor package as claimed in claim 12, wherein the
substrate further has a plurality of solder balls for electrically
connecting an external circuit.
14. The semiconductor package as claimed in claim 12, further
comprising: a plurality of bonding wires for electrically
connecting the chip to the substrate.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of Taiwan
patent application serial No. 091135502, filed on Dec. 3, 2002, and
the full disclosure thereof is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a semiconductor package
with a high-frequency element, and more particularly, to a
semiconductor package with a cavity formed in the encapsulant
corresponding to a high-frequency element thereof so as to avoid
the influence of the encapsulant upon the high-frequency
element.
[0004] 2. Description of the Related Art
[0005] The package has four major functions, i.e. signal
distribution, power distribution, heat dissipation, and protection.
In general, the semiconductor chip is formed into an enclosure,
such as a single-chip module (SCM) or a chip carrier, referred to
as a first-level package, i.e. the packaging of the semiconductor.
These packaged chips, along with other components such as
capacitors, resistors, inductors, filters, switches, and optical
and RF components, are assembled to a printed wiring board in a
second-level package.
[0006] In the prior art, there exist varied packages, such as a
small outline package (SOP), a quad flat package (QFP), a ball grid
array (BGA) package, and so on.
[0007] Referring to FIG. 1, it depicts a typical ball grid array
package 10. The package 10 generally has a substrate 14 and a chip
18 attached on the substrate 14 by an adhesive 28. The chip 18 is
electrically connected to the substrate 14 through a plurality of
bonding wires 16. An encapsulant 12 encapsulates the substrate 14,
the chip 18, and the bonding wires 16. The substrate 14 further has
a plurality of solder balls 24 for electrically connecting an
external circuit.
[0008] The active surface 26 of the chip 18 typically directly
touches the encapsulant 12. However, in a specific case, the chip
18 is provided with a high-frequency circuit or element disposed in
a high-frequency area 20 on the active surface 26. The signal
propagation speed Vp in the high-frequency element is derived from
the following equation:
Vp=C/{square root}{square root over ( )}(.epsilon..sub.r)
[0009] where C is the speed of light in vacuum and .epsilon..sub.r
is effective or equivalent dielectric constant. As the
high-frequency element is exposed to air, the effective dielectric
constant ranges from 1 (the dielectric constant of air) to 4 (the
dielectric constant of G-10 or FR-4 substrate which is constructed
from a woven glass fabric with an epoxy resin binder). However,
while the high-frequency area 20 is covered with the encapsulant
12, the dielectric constant of the encapsulant 12 is larger than
that of the air and thus the effective dielectric constant ranges
from the dielectric constant of the encapsulant 12 to the
dielectric constant of the substrate 14. Therefore, the effective
dielectric constant of the substrate covered with the encapsulant
12 is larger than that of the substrate exposed to the air.
Furthermore, the loss factor or loss tangent of the high-frequency
circuit is also increased because of the covering of the
encapsulant 12.
[0010] Accordingly, there exists a need for a semiconductor package
which is provide with a cavity to prevent the high-frequency
element from contacting the encapsulant and avoid the disadvantages
due to the contact.
SUMMARY OF THE INVENTION
[0011] It is an object of the present invention to provide a
semiconductor package with a cavity positioned above the
high-frequency area of the semiconductor chip such that the
propagation speed of the high-frequency circuit is not reduced.
[0012] In order to achieve the above object, the present invention
provides a semiconductor package comprising a first chip, a
substrate, a middle layer, a second chip, and an encapsulant. The
first chip has an active surface and a high-frequency element
defining a high-frequency area on the active surface. The substrate
supports the first chip and is electrically connected to the first
chip. The middle layer is disposed on the first chip and has a
recess corresponding to the high-frequency area. The second chip is
disposed on the middle layer and electrically connected to either
the first chip or the substrate. The encapsulant encapsulates the
first chip, the middle layer, the second chip, and a part of the
substrate.
[0013] Accordingly, the high-frequency element of the semiconductor
package according to the present invention is not covered with or
touched by the encapsulant, and thus the propagation speed of the
high-frequency element may not be reduced by the influence of the
encapsulant. Furthermore, the high-frequency element is not covered
with the encapsulant and thus the loss tangent thereof is not
increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other objects, advantages, and novel features of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawing.
[0015] FIG. 1 is a schematic cross-sectional view of a
semiconductor package in the prior art.
[0016] FIG. 2 is a schematic cross-sectional view of a
semiconductor package according to an embodiment of the present
invention.
[0017] FIG. 3 is a schematic cross-sectional view of a
semiconductor package according to another embodiment of the
present invention.
[0018] FIG. 4 is a schematic cross-sectional view of a
semiconductor package according to a further embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Referring to FIG. 2, it depicts a semiconductor package 100
according to an embodiment of the present invention. The
semiconductor package 100 is a multi-chip package and has a first
chip 118 attached to a substrate 114 by an adhesive 128, and a
second chip 130 disposed on the first chip 118.
[0020] The first chip 118 has an active surface 126 electrically
connected to the substrate 114 by a plurality of bonding wires 116.
The substrate 114 further has a plurality of solder balls 124 for
connecting an external circuit. The first chip 118 has
high-frequency circuits or elements disposed in a high-frequency
area 120 on the active surface 126 of the first chip 118.
[0021] A middle layer 132 is disposed on the active surface 126 of
the first chip 118 and has a recess 134 corresponding to the
high-frequency area 120. The middle layer 132 can be an adhesive,
such as made of epoxy, and be applied on the active surface 126 by
screen-printing, thereby forming the recess 134. The second chip
130 is disposed on the middle layer 132 and electrically connected
to the first chip by a plurality of bonding wires 136. An
encapsulant 112 encapsulates the substrate 114, the first chip 118,
the middle layer 132, the second chip 130, and the bonding wires
116 and 136.
[0022] In this arrangement, the high-frequency area 120 of the
first chip 118 is exposed to the recess 134, so the propagation
speed of the high-frequency element in the high-frequency area 120
is free from the influence of the encapsulant 112 and thus is not
reduced. Furthermore, without being covered by the encapsulant 112,
the loss tangent of the high-frequency element is not increased. It
should be noticed that the recess 134 shown in the drawing is a
through hole, but the recess 134 is used for providing a space
above the high-frequency area and can be a non-through hole, i.e. a
depression.
[0023] Referring to FIG. 3, it depicts a semiconductor package 200
according to another embodiment of the present invention. The
semiconductor package 200 is a type of flip chip package and has a
chip 218 having an active surface 226 which is electrically
connected to a substrate 214 by bumps 216. An encapsulant 212 is
filled between the active surface 226 of the chip 218 and the
substrate 214 by the underfill dispensing process. The substrate
214 is adapted for electrically connecting an external circuit.
[0024] The chip 218 has a high-frequency circuit or element
disposed in a high-frequency area 220 on the active surface 126 of
the first chip 118. As shown in the drawing, the active surface 226
of the chip 218 faces the substrate 214. The encapsulant 212 has a
cavity 234 (a through hole shown in the drawing), the position of
which is corresponding to that of the high-frequency area 220. In
this arrangement, the high-frequency area 220 is exposed to the
cavity 234, so the propagation speed of the high-frequency element
in the high-frequency area 220 is free from the influence of the
encapsulant 212 and is not reduced.
[0025] It will be apparent to those skilled in the art that the
cavity 234 or the through hole can be formed by dispensing and
performing a dam (not shown).
[0026] Furthermore, the substrate 214 can be provided with a notch
236 disposed thereon corresponding to the high-frequency area 220
for increasing the volume of the space above the high-frequency
area 220 and further reducing the influence upon the high-frequency
area.
[0027] Referring to FIG. 4, it depicts a semiconductor package 300
according to a further embodiment of the present invention. The
semiconductor package 300 has a chip 318 which is attached to the
substrate 214 by an adhesive layer 328. The chip 318 has an active
surface 326 which is electrically connected to the substrate 314 by
a plurality of bonding wires 316. The substrate 14 is further
provided with a plurality of solder balls 324 for connecting an
external circuit.
[0028] The chip 318 has a high-frequency circuit or element
disposed in a high-frequency area 320 on the active surface 326 of
the chip 318. An encapsulant 312 encapsulates the substrate 314,
the chip 318, and the bonding wires 316. As shown in the drawing,
the encapsulant 312 has a cavity 334 corresponding to the
high-frequency area 320. It will be apparent to those skilled in
the art that the cavity 334 can be formed in the encapsulant 312 by
pre-locating a lip (not shown) thereon and then molding the
encapsulant 312.
[0029] It will be apparent to those skilled in the art that the
principle and spirit of the present invention is that a space
positioned above the high-frequency element of a semiconductor chip
is provided such that the influence upon the operation of the
high-frequency element is avoided. The principle of the present
invention is not limited to be applied to the embodiments shown in
the drawings and can be applied to other packages, such as small
outline packages, quad flat packages, ball grid array packages and
so on. The above-mentioned substrate can be easily replaced with a
lead frame.
[0030] As mentioned above, the high-frequency element of the
semiconductor package according to the present invention is not
covered with or touched by the encapsulant, and thus the
propagation speed of the high-frequency element may not be reduced
by the influence of the encapsulant. Furthermore, the
high-frequency element is not covered with the encapsulant and thus
the loss tangent thereof is not increased.
[0031] While the foregoing description and drawings represent the
preferred embodiments of the present invention, it will be
understood that various additions, modifications and substitutions
may be made therein without departing from the spirit and scope of
the principles of the present invention as defined in the
accompanying claims. One skilled in the art will appreciate that
the invention may be used with many modifications of form,
structure, arrangement, proportions, materials, elements, and
components and otherwise, used in the practice of the invention,
which are particularly adapted to specific environments and
operative requirements without departing from the principles of the
present invention. The presently disclosed embodiments are
therefore to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims and their legal equivalents, and not limited to the
foregoing description.
* * * * *