U.S. patent application number 11/133278 was filed with the patent office on 2006-11-23 for semiconductior package substrate with embedded resistors and method for fabricating same.
This patent application is currently assigned to Phoenix Precision Technology Corporation. Invention is credited to Zao-Kuo Lai, Lin-Yin Wong.
Application Number | 20060261462 11/133278 |
Document ID | / |
Family ID | 37397637 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060261462 |
Kind Code |
A1 |
Lai; Zao-Kuo ; et
al. |
November 23, 2006 |
SEMICONDUCTIOR PACKAGE SUBSTRATE WITH EMBEDDED RESISTORS AND METHOD
FOR FABRICATING SAME
Abstract
A semiconductor package substrate with embedded resistors and a
method for fabricating the same are proposed. Firstly, an inner
circuit board having a first circuit layer thereon is provided, and
a plurality of resistor electrodes are formed in the fist circuit
layer. Then, a patterned resistive material is formed on the inner
circuit board and electrically connected to the resistor electrodes
to accurately define a resistance value of resistors. Subsequently,
at least one insulating layer is coated on a surface of the circuit
board having the patterned resistive material. At least one
patterned second circuit layer is formed on the insulating layer
and electrically connected to the resistor electrodes by a
plurality of conductive vias formed in the insulating layer or
plated through holes formed through the circuit board.
Inventors: |
Lai; Zao-Kuo; (Hsin-chu,
TW) ; Wong; Lin-Yin; (Hsin-chu, TW) |
Correspondence
Address: |
SQUIRE, SANDERS & DEMPSEY L.L.P.
14TH FLOOR
8000 TOWERS CRESCENT
TYSONS CORNER
VA
22182
US
|
Assignee: |
Phoenix Precision Technology
Corporation
|
Family ID: |
37397637 |
Appl. No.: |
11/133278 |
Filed: |
May 20, 2005 |
Current U.S.
Class: |
257/698 ;
257/536; 257/700; 257/924; 257/E23.062; 438/382 |
Current CPC
Class: |
H05K 2203/1453 20130101;
H01L 23/49822 20130101; H01L 2924/15311 20130101; H01L 2224/05573
20130101; H01L 2924/01078 20130101; H01L 2224/0554 20130101; H05K
1/167 20130101; H01L 21/4857 20130101; H01L 2924/00014 20130101;
H01L 2924/04941 20130101; H05K 3/4644 20130101; H01L 2224/05568
20130101; H01L 2224/16 20130101; H05K 3/429 20130101; H01L
2924/00014 20130101; H01L 2224/05599 20130101; H01L 2924/00014
20130101; H01L 2224/0555 20130101; H01L 2924/00014 20130101; H01L
2224/0556 20130101 |
Class at
Publication: |
257/698 ;
257/700; 257/924; 257/536; 438/382 |
International
Class: |
H01L 31/062 20060101
H01L031/062; H01L 21/20 20060101 H01L021/20 |
Claims
1. A method for fabricating a semiconductor package substrate with
embedded resistors, the method comprising the steps of: providing
an inner circuit board having a patterned first circuit layer
thereon, the first circuit layer having a plurality of resistor
electrodes; forming a patterned resistive material on the inner
circuit board, and allowing the patterned resistive material to be
electrically connected to the resistor electrodes and to partially
or completely cover the resistor electrodes; applying at least one
insulating layer on a surface of the inner circuit board having the
patterned resistive material; and forming at least one patterned
second circuit layer on the insulating layer, and allowing the
patterned second circuit layer to be electrically connected to the
resistor electrodes by a plurality of conductive vias formed in the
insulating layer.
2. The method of claim 1, wherein the inner circuit board is one
selected from the group consisting of a double-layer circuit board
and a multi-layer circuit board.
3. The method of claim 1, wherein the step of forming the patterned
resistive material on the inner circuit board comprises: coating a
layer of the resistive material on the inner circuit board; and
patterning the resistive material and allowing the resistive
material to be electrically connected to the resistor
electrodes.
4. The method of claim 1, wherein the step of forming the patterned
resistive material on the inner circuit board comprises: depositing
the resistive material on the resistor electrodes via a
screen-printing technique; and accurately defining a resistance
value of the resistive material, such that the resistive material
is electrically connected to the resistor electrodes.
5. The method of claim 1, wherein the step of forming the patterned
resistive material on the inner circuit board comprises: forming a
patterned resist layer on the inner circuit board to define an area
for depositing the resistive material; depositing the resistive
material in openings of the patterned resist layer, such that the
resistive material is electrically connected to the resistor
electrodes; and removing the resist layer.
6. (canceled)
7. (canceled)
8. (canceled)
9. (canceled)
10. (canceled)
11. A method for fabricating a semiconductor package substrate with
embedded resistors, comprising the steps of: providing an inner
circuit board having a patterned first circuit layer thereon, the
first circuit layer having a plurality of resistor electrodes;
forming a patterned resistive material on the inner circuit board,
and allowing the patterned resistive material to be electrically
connected to the resistor electrodes; applying at least one
insulating layer on a surface of the inner circuit board having the
patterned resistive material; forming a plurality of plated through
holes through the insulating layer and the first circuit layer, and
allowing the plated through holes to be electrically connected to
the first circuit layer and the resistor electrodes; and forming at
least one patterned second circuit layer on the insulating layer,
and allowing the patterned second circuit layer to be electrically
connected to the resistor electrodes by a plurality of conductive
vias formed in the insulating layer.
12. The method of claim 11, wherein the inner circuit board is one
selected from the group consisting of a double-layer circuit board
and a multi-layer circuit board.
13. The method of claim 11, wherein the step of forming the
patterned resistive material on the inner circuit board comprises:
coating a layer of the resistive material on the inner circuit
board; and patterning the resistive material layer, such that the
resistive material is electronically connected to the resistor
electrodes.
14. The method of claim 11, wherein the step of forming the
patterned resistive material on the inner circuit board comprises:
depositing the resistive material on the resistor electrodes via a
screen-printing technique; and accurately defining a resistance
value of the resistive material, such that the resistive material
is electrically connected to the resistor electrodes.
15. The method of claim 11, wherein the step of forming the
patterned resistive material on the inner circuit board comprises:
forming a patterned resist layer on the inner circuit board to
define an area for depositing the resistive material; depositing
the resistive material in openings of the patterned resist layer,
such that the resistive material is electrically connected to the
resistor electrodes; and removing the resist layer.
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
Description
FIELD OF THE INVENTION
[0001] The present invention relates to semiconductor package
substrates with embedded resistors and methods for fabricating the
same, and more particularly, to a semiconductor package substrate
having resistors embedded in a multi-layer circuit board and a
method for fabricating the substrate, so as to provide good
electrical performances for a semiconductor device using the
substrate.
BACKGROUND OF THE INVENTION
[0002] Owing to the progress of semiconductor packaging technology
and improvements in electrical performances for semiconductor
chips, semiconductor devices are developed toward high integration.
For example, a ball grid array (BGA) semiconductor device is
characterized in that a plurality of array-arranged solder balls
are formed on a bottom surface of a substrate and used as
input/output (I/O) connections for electrically connecting a
semiconductor chip mounted on the substrate to an external device
such as printed circuit board (PCB). Compared to a conventional
lead-frame based semiconductor device, the BGA semiconductor device
advantageously provides more I/O connections on the same unit area
of a chip carrier such as the substrate, and thus can accommodate
more electronic circuits and semiconductor chips therein.
[0003] In accordance with high integration of the semiconductor
device, more leads or contacts are required and also more noise is
caused. Generally, for solving the noise problem, passive
components such as resistors, capacitors and inductors are
incorporated in the semiconductor device so as to eliminate the
noise and stabilize the circuits, making a semiconductor chip
packaged in the device have specific current characteristics.
[0004] FIG. 1 is a cross-sectional view showing a conventional
passive component being mounted on a surface of a substrate. At
least one pair of separate bond pads 11 are formed at predetermined
positions on the surface of the substrate 10 and are exposed to a
solder mask layer 12 that covers the substrate 10. Then, a solder
paste 13 is applied on the bond pads 11, and two ends 140 of at
least one passive component 14 are respectively attached to the
bond pads 11 via the solder paste 13. A reflow process is performed
to allow the passive component 14 to be bonded and electrically
connected to the bond pads 11 on the substrate 10 via the solder
paste 13. However, it is difficult to accurately control an applied
amount of the solder paste 13, and the height of the solder paste
13 after being reflowed, as well as the surface flatness of the
solder mask layer 12. Thereby, a gap 15 is usually left between the
passive component 14 and the solder mask layer 12. In a
high-temperature environment during subsequent fabrication
processes, the solder paste 13 would melt or become softened and
leaks to the gap 15 due to capillary attraction, which causes
bridging of the solder paste 13 applied on the two bond pads 11 and
short-circuiting of the passive components 14, and thus adversely
affects the production yield.
[0005] Referring to FIG. 2 disclosed in U.S. Pat. No. 6,108,212, a
bond pad 21 and at least one electrode 22 are formed on a surface
of a substrate 20, and an electrically resistive volume 23 is
disposed between the bond pad 21 and the electrode 22 to form a
passive component comprising the bond pad 21, the electrode 22 and
the electrically resistive volume 23. This allows the substrate 20
to be electrically connected to an external electronic device 25
such as printed circuit board by means of a metal bump 24 bonded to
the bond pad 21. Also, the passive component formed by the bond pad
21, the electrode 22 and the electrically resistive volume 23
provides improved electrical performances for the semiconductor
device. A pitch distance between the bond pad and the electrode on
the surface of the substrate should be sufficiently large for
successfully forming the electrically resistive volume having
resistor effects. However, since the substrate has a limited
surface area, a relatively large area occupied by the resistor
would affect a layout of other circuits arranged on the substrate
surface. This thus reduces flexibility of circuit routability on
the substrate, sets a limitation on the number of passive
components that can be incorporated on the substrate, and does not
facilitate the high integration development for the semiconductor
device. Furthermore, by the fact that the number of passive
components to be incorporated is dramatically increased along with
the requirement of high performances for the semiconductor device,
if the foregoing method in which a semiconductor chip and a large
number of passive components are simultaneously mounted on the
substrate surface is employed, the size miniaturization for the
semiconductor device can hardly be achieved.
[0006] In order to solve the above problem, U.S. Pat. No. 6,278,356
discloses a substrate 30 having a built-in layer passive component.
Referring to FIG. 3, a copper layer 32 is formed respectively on an
upper surface and a lower surface of an insulating layer 31, and
the copper layer 32 is provided with an etching pattern 320. Then,
a dielectric layer 33 is printed on the copper layer 32 and fills
openings in the etching pattern 320. Subsequently, a resistive
layer 34 is formed over the copper layer 32 and the dielectric
layer 33 by the printing technique, wherein the resistive layer 34
serves as a resistor, and the dielectric layer 33 filling the
openings in the etching patter 320 serves as a capacitor, so as to
integrate a plurality of passive components on the substrate
30.
[0007] However, in the foregoing structure, only the printing
technique is used to form the dielectric layer 33 and the resistive
layer 34 on the substrate 30, such that it is difficult to
accurately control the capacitance and resistance thereof
respectively. Additionally, since the resistive layer 34 covers
both the copper layer 32 and the dielectric layer 33 that are made
of different materials, a reliability issue may be generated in a
high-temperature and high-moisture environment during subsequent
fabricating processes or tests, and thus electrical connection
between the resistive layer and electrodes may also be
affected.
[0008] Moreover, along with the blooming development of electronic
industry, electronic products are gradually becoming more
multi-functional and high efficient. In order to satisfy the
requirements of high integration and size miniaturization for
semiconductor packages, a circuit board for carrying active/passive
components and circuits has been developed from a single-layer
structure to a multi-layer board that employs the interlayer
connection technique to enlarge usable circuit area on the circuit
board, so as to incorporate a high circuit density in the circuit
board. However, the foregoing prior art only discloses that passive
components can be mounted on the surface of the substrate but does
not provide a strategy to apply passive components to a multi-layer
package substrate in accordance with the requirements of high
integration and size miniaturization for the semiconductor
package.
[0009] Therefore, the problem to be solved here is to incorporate
an effective number of electronic elements such as passive
components and semiconductor chips in a semiconductor package
substrate with multiple layers of circuits, which can assure the
fabrication reliability and accuracy and improve electrical
performance of electronic products, without affecting circuit
routability of the substrate and increasing the overall thickness
of the semiconductor package, so as to meet the requirements of
compact size, multiple functions and high electrical performances
of the electronic products.
SUMMARY OF THE INVENTION
[0010] In light of the above drawbacks in the prior art, a primary
objective of the present invention is to provide a semiconductor
package substrate with embedded resistors and a method for
fabricating the same, by which a multi-layer package substrate
integrated with resistors is formed to meet the requirements of
high integration and size miniaturization for semiconductor
packages.
[0011] Another objective of the present invention is to provide a
semiconductor package substrate with embedded resistors and a
method for fabricating the same, by which a surface area being used
on the substrate is reduced to make a semiconductor device compact
in size.
[0012] Still another objective of the present invention is to
provide a semiconductor package substrate with embedded resistors
and a method for fabricating the same, which can improve the
fabrication reliability and accuracy in resistance of the
resistors.
[0013] A further objective of the present invention is to provide a
semiconductor package substrate with embedded resistors and a
method for fabricating the same, which can increase the number of
passive components incorporated in a semiconductor device and
improve flexibility of circuit routability of the substrate.
[0014] In accordance with the above and other objectives, the
present invention proposes a semiconductor package substrate with
embedded resistors. The resistors embedded in the substrate can
thus be incorporated in a semiconductor device using the substrate
without influencing circuit routability on the surface of the
substrate.
[0015] The present invention also proposes a method for fabricating
the above semiconductor package substrate with embedded resistors,
which comprises the following steps. First, an inner circuit board
having a first circuit layer thereon is provided and a plurality of
resistor electrodes are formed in the first circuit layer.
Subsequently, a patterned resistive material is formed on the inner
circuit board and electrically connected to the resistor electrodes
to define a resistance value of resistors. At least one insulating
layer is formed on a surface of the circuit board having the
patterned resistive material, and a plurality of vias are formed in
the insulating layer to expose the resistor electrodes. Then, at
least one second circuit layer is formed on the surface of the
insulating layer, such that the second circuit layer is
electrically connected to the resistor electrodes by the plurality
of vias formed in the insulating layer.
[0016] A semiconductor package substrate with embedded resistors
fabricated by the foregoing method in the present invention
comprises: an inner circuit board having a first circuit layer
thereon, the first circuit layer having a plurality of resistor
electrodes; at least one patterned resistive material formed on the
inner circuit board and electrically connected to the resistor
electrodes to define a resistance value of resistors; at least one
patterned second circuit layer formed on a surface of the circuit
board having the patterned resistive material and spaced from the
patterned resistive material by an insulating layer; and a
plurality of conductive vias formed in the insulating layer, for
electrically connecting the second circuit layer to the resistor
electrodes.
[0017] In another embodiment, the method for fabricating a
semiconductor package substrate with embedded resistors in the
present invention comprises the following steps. First, an inner
circuit board having a first circuit layer thereon is provided and
a plurality of resistor electrodes are formed in the first circuit
layer. Subsequently, a patterned resistive material is formed on
the inner circuit board and electrically connected to the resistor
electrodes to define a resistance value of resistors. At least one
insulating layer is formed on a surface of the circuit board having
the patterned resistive material, and at least one patterned second
circuit layer is formed on the insulating layer. A plurality of
plated through holes (PTH) are formed through the circuit board.
And a plurality of conductive vias are formed in the insulating
layer and electrically connect the second circuit layer to the
resistor electrodes.
[0018] By the above fabrication method, a semiconductor package
substrate with embedded resistors proposed in the present invention
is obtained comprising: an inner circuit board having a first
circuit layer thereon, the first circuit layer having a plurality
of resistor electrodes; at least one patterned resistive material
formed on the inner circuit board and electrically connected to the
resistor electrodes; at least one patterned second circuit layer
formed on a surface of the circuit board having the patterned
resistive material and spaced from the patterned resistive material
by an insulating layer; a plurality of plated through holes formed
through the insulating layer and the circuit layers, and
electrically connected to the circuit layers and the resistor
electrodes; and a plurality of conductive vias formed in the
insulating layer, for electrically connecting the second circuit
layer to the resistor electrodes.
[0019] For the semiconductor package substrate with embedded
resistors and the method for fabricating the same proposed in the
present invention, a patterned first circuit layer is first formed
on an inner circuit board and is provided with a plurality of
resistor electrodes. Then, a patterned resistive material is
applied on the inner circuit board and electrically connected to
the resistor electrodes to define a resistance value of resistors.
That is, the resistance value can be accurately determined
according to the type of resistive material being used and the size
such as length and area of the effective resistive material formed
between the resistor electrodes, so as to improve accuracy in the
resistance value of the resistors and reliability of the
fabrication processes. Furthermore, the circuit layers can be
electrically connected to the resistor electrodes by means of a
plurality of plated through holes or conductive vias, so as to form
a multi-layer package substrate with embedded resistors. This thus
increases the number of passive components incorporated in the
semiconductor device and improves flexibility of the circuit
routability of the substrate, to meet the requirements of high
integration and size miniaturization for the semiconductor
package.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The present invention can be more fully understood by
reading the following detailed description of the preferred
embodiments, with reference made to the accompanying drawings,
wherein:
[0021] FIG. 1 (PRIOR ART) is a cross-sectional view showing a
conventional passive component being mounted on a surface of a
substrate;
[0022] FIG. 2 (PRIOR ART) is a cross-sectional view of a substrate
integrated with passive components according to U.S. Pat. No.
6,108,212;
[0023] FIG. 3 (PRIOR ART) is a cross-sectional view of a substrate
integrated with passive components according to U.S. Pat. No.
6,278,356;
[0024] FIGS. 4A to 4G are cross-sectional views showing procedural
steps of a method for fabricating a semiconductor package substrate
with embedded resistors according to a preferred embodiment of the
present invention; and
[0025] FIGS. 5A to 5H are cross-sectional views showing procedural
steps of a method for fabricating a semiconductor package substrate
with embedded resistors according to another preferred embodiment
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] FIGS. 4A to 4G show the procedural steps of a method for
fabricating a semiconductor package substrate with embedded
resistors according to a preferred embodiment of the present
invention.
[0027] First, referring to FIG. 4A, an inner circuit board 41 is
provided and a conductive metal layer 42 is formed on a surface of
the inner circuit board 41. The conductive metal layer 42 can be
made of copper metal or any other conductive metal. The inner
circuit board 41 may be a double-layer circuit board or a
multi-layer circuit board.
[0028] Referring to FIG. 4B, the conductive metal layer 42 is
patterned to form a first circuit layer 43 by an etching process.
Alternatively, the inner circuit board 41 can be a multi-layer
circuit board and the first circuit layer 43 is formed on a
superficial insulating layer of the multi-layer circuit board. The
first circuit layer 43 comprises a plurality of resistor electrodes
430 for being subsequently electrically connected to resistors.
[0029] Referring to FIG. 4C, a resistive material 44 is applied on
the inner circuit board 41. The resistive material 44 can be a
thick film resistive material or a thin film resistive material.
The thick film resistive material may be made of silver powders or
carbon particles dispersed in a resin, or ruthenium oxide
(RuO.sub.2) and glass powders dispersed in a binder to be applied
and cured. As shown in FIG. 4C, the thick film resistive material
44 on the inner circuit board 41 is patterned by a laser or etching
technique, allowing the resistive material 44 to be electrically
connected to the resistor electrodes 430 and partially or
completely cover the electrodes 430, such that the resistance of
resistors can be accurately defined and the reliability thereof can
also be improved (as shown in FIG. 4D). Alternatively, the thick
film resistive material 44 can be directly deposited on the
resistor electrodes 430 by a screen-printing technique.
Subsequently, the thick film resistive material 44 can be patterned
by the laser or etching technique to be electrically connected to
the resistor electrodes 430 and accurately define the resistance of
the resistive material 44.
[0030] Alternatively, referring to FIGS. 4C' and 4D', if the
resistive material 44 is the thin film resistive material such as
nickel-chromium (Ni--Cr) alloy, nickel-phosphorus (Ni--P) alloy,
nickel-tin (Ni--Sn) alloy, chromium-aluminum (Cr--Al) alloy or
titanium nitride (TaN) alloy, a patterned thin film resist layer
440 is first formed on the substrate to define an area for
depositing the thin film resistive material. Then, the thin film
resistive material 44 is deposited in openings of the resist layer
440 by a sputtering, electroplating or electroless plating
technique, so as to allow the resistive material 44 to partially or
completely cover the resistor electrodes 430 and be electrically
connected to the resistor electrodes 430. Subsequently, the resist
layer 440 is removed. In this embodiment, the subsequent
fabrication processes are described primarily for fabricating
build-up layers on the thick film resistive material.
[0031] The selection of either the thick film resistive material or
the thin film resistive material depends on the fabrication cost of
a multi-layer package substrate and the electrical accuracy of
passive components being fabricated. Further, a desirable
resistance value required for the semiconductor package substrate
can be determined according to the type of resistive material being
used and the size of the resistive material formed between the
resistor electrodes. The resistive material may partially or
completely cover the electrodes, so as to prevent a reliability
issue caused in a high-temperature and high-moisture environment
during subsequent fabrication processes and tests, and not to
influence the electrical connection between the resistive material
and the electrodes.
[0032] Referring to FIG. 4E, at least one insulating layer 45 is
formed over the patterned resistive material 44 on the surface of
the circuit board 41. The insulating layer 45 can be made of an
insulating organic material or a ceramic material, such as epoxy
resin, polyimide, bismaleimide triazine-based resin, photoimagable
resin, or a composite material thereof with glass fibers. A roller
coating, printing or lamination technique can be applied to form
the insulating layer 45. It should be understood that the
insulating layer 45 is not limited to being made of a single
organic material, but can also be laminated by different insulating
material layers.
[0033] Referring to FIG. 4F, a plurality of vias 450 are formed in
the insulating layer 45 by one of a mechanical drilling, laser
drilling technique, or photolithographic technique, wherein at
least one of the vias 450 exposes at least one of resistor
electrodes 430.
[0034] Referring to FIG. 4G, a patterned second circuit layer 46
and a plurality of conductive vias 451 are respectively formed on a
surface of the insulating layer 45 and in the vias 450, such that
the second circuit layer 46 is electrically connected to the
resistor electrodes 430 by the conductive vias 451. This thereby
completely fabricates a multi-layer package substrate with embedded
resistors. The second circuit layer can be formed by a build-up or
lamination technique; for example, an electroplating process may be
used together with the build-up technique to form such patterned
circuit layer, or alternatively, a copper foil can be pressed and
etched to form the patterned circuit layer. Certainly, more
insulating layers and circuit layers can be further built up on a
surface of the substrate to fabricate a package substrate with more
circuit layers. The substrate can be a flip-chip package substrate
or a wire-bonding package substrate.
[0035] FIGS. 5A to 5H show the procedural steps of a method for
fabricating a semiconductor package substrate with embedded
resistors according to another preferred embodiment of the present
invention, wherein the fabrication processes shown in FIGS. 5A to
5E are the same as those in FIGS. 4A to 4E and therefore not to be
further repeated here.
[0036] Referring to FIG. 5F, after the resistive material 44 on the
first circuit layer 43 is patterned by the laser or etching
technique and the resistors corresponding to the resistor
electrodes 430 of the first circuit layer 43 are embedded, a
plurality of through holes 47 are formed through the substrate by
the mechanical drilling or laser drilling technique.
[0037] Referring to FIG. 5G, a conductive metal layer 48 such as
copper layer is plated on surfaces of the substrate and inner walls
of the through holes 47. Then, a filling material such as an
insulating material e.g. epoxy resin or a conductive material e.g.
solder paste is used to fill the through holes 47, so as to form
plated through holes (PTHs) 470 that are electrically connected to
the resistor electrodes 430.
[0038] Referring to FIG. 5H, a plurality of conductive vias 451 are
formed in the insulating layer 45 and at least one patterned second
circuit layer 49 is formed on the insulating layer 45, such that
the second circuit layer 49 is electrically connected to the
resistor electrodes 430 by the conductive vias 451. This thereby
completely fabricates a multi-layer package substrate with embedded
resistors. Certainly, more insulating layers and circuit layers can
be further built up on a surface of the substrate to fabricate a
package substrate with more circuit layers. The substrate can be a
flip-chip package substrate or a wire-bonding package
substrate.
[0039] FIGS. 4G and 5H respectively show a semiconductor package
substrate with embedded resistors according to the present
invention.
[0040] This package substrate comprises an inner circuit board 41,
at least one insulating layer 45, a circuit layer 46, 49 formed on
the insulating layer 45, at least one resistive material 44, a
plurality of resistor electrodes 430 electrically connected to the
resistive material, a plurality of plated through holes 470 for
electrically connecting the circuit layer to the resistor
electrodes, and a plurality of conductive vias 451 formed through
the insulating layer and for electrically connecting the circuit
layer to the resistor electrodes.
[0041] The insulating layer 45 can be made of an organic materials,
a fiber-reinforced organic material, a particle-reinforced organic
material, such as epoxy resin, polyimide, bismaleimide
triazine-based resin, or cyanate. The circuit layer 46, 49 can be a
patterned copper layer formed by etching or electroplating
technique.
[0042] The resistive material 44 comprise thick film resistive
passive components or thin film resistive passive components. The
thick film resistive material is made of silver powders or carbon
particles dispersed in a resin, and ruthenium oxide (RuO.sub.2) and
glass powders dispersed in a binder to be applied and cured. The
thin film resistive material is made of nickel-chromium (Ni--Cr)
alloy, nickel-phosphorus (Ni--P) alloy, nickel-tin (Ni--Sn) alloy,
chromium-aluminum (Cr--Al) alloy, or titanium nitride (TaN) alloy,
etc., which can be formed by the sputtering, electroplating or
electroless plating technique. The selection of either the thick
film resistive material or the thin film resistive material depends
on the fabrication cost of the multi-layer substrate and the
electrical accuracy of the resistors being fabricated. Further, a
desirable resistance value required for the semiconductor package
substrate can be determined according to the type of resistive
material being used and the size of the resistive material formed
between the resistor electrodes.
[0043] The plated through holes 470 are fabricated by forming
through holes in the substrate using the mechanical drilling or
laser drilling technique, then coating a conductive metal layer
such as copper layer over surfaces of the substrate and inner walls
of the through holes, and finally applying a filling material such
as an insulating material e.g. epoxy resin or a conductive material
e.g. solder paste for filling the through holes. The fabricated
plated through holes 470 are electrically connected to the resistor
electrodes.
[0044] By the semiconductor package substrate with embedded
resistors and the method for fabricating the same proposed in the
present invention, the resistors are embedded in the substrate and
can be incorporated in a semiconductor device using the substrate,
such that the number and electrical performances of passive
components provided in the semiconductor device can both be
increased, and flexibility of circuit routability of the substrate
can also be improved, as well as the area being used on the
substrate can be reduced, which favors the size miniaturization of
the semiconductor device.
[0045] For the semiconductor package substrate with embedded
resistors and the method for fabricating the same proposed in the
present invention, a patterned first circuit layer is first formed
on an inner circuit board and is provided with a plurality of
resistor electrodes. At least one resistive material is applied on
a surface of the inner circuit board and patterned according to a
desirable resistance value required by actual electrical
performances, allowing the resistive material to partially or
completely cover the resistor electrodes. That is, the desirable
resistance value can be accurately determined according to the type
of resistive material being used and the size such as length and
area of the effective resistive material formed between the
resistor electrodes, so as to prevent a reliability issue caused in
a high-temperature and high-moisture environment during the
subsequent fabrication processes and tests, and not to influence
the electrical connection between the resistive material and the
electrodes. As a result, accuracy in the resistance value of the
resistors and reliability of the fabrication processes are both
improved. Furthermore, the circuit layers can be electrically
connected to the resistor electrodes by means of a plurality of
plated through holes or conductive vias, so as to form a
multi-layer package substrate with embedded resistors. This thus
increases the number of passive components incorporated in the
semiconductor device and improves flexibility of the circuit
routability of the substrate, to meet the requirements of high
integration and size miniaturization for the semiconductor
package.
[0046] The foregoing drawings only show the partial resistive
material. Practically, the numbers and the corresponding positions
of the resistive material and the circuit layer are flexibility
arranged between the laminated layers of the substrate. The
resistive material can be formed on any inner circuit layer in a
circuit board and is not limited to being formed on a core circuit
layer of the circuit board. Also, the above fabrication processes
can be applied to a single side or double sides of the inner
circuit board.
[0047] The invention has been described using exemplary preferred
embodiments. However, it is to be understood that the scope of the
invention is not limited to the disclosed embodiments. On the
contrary, it is intended to cover various modifications and similar
arrangements. The scope of the claims, therefore, should be
accorded the broadest interpretation so as to encompass all such
modifications and similar arrangements.
* * * * *