U.S. patent application number 13/564673 was filed with the patent office on 2013-11-28 for method for fabricating conductive structures of substrate.
This patent application is currently assigned to Viking Tech Corporation. The applicant listed for this patent is Chien-Hung Ho, Shen-Li Hsiao, Chen-Shen Kuo, Yuan-Chiang Lin, Shih-Long Wei. Invention is credited to Chien-Hung Ho, Shen-Li Hsiao, Chen-Shen Kuo, Yuan-Chiang Lin, Shih-Long Wei.
Application Number | 20130313122 13/564673 |
Document ID | / |
Family ID | 49620744 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130313122 |
Kind Code |
A1 |
Wei; Shih-Long ; et
al. |
November 28, 2013 |
Method For Fabricating Conductive Structures of Substrate
Abstract
A method for fabricating a conductive structure of a substrate
includes the steps of: providing an insulating substrate having
opposite first and second surfaces and forming an insulating
adhesive film on the second surface of the insulating substrate;
forming at least a through hole penetrating the insulating
substrate and the insulating adhesive film and forming a conductive
foil on the insulating adhesive film so as to cover the through
hole; and forming a shielding material on the conductive foil and
the second surface of the insulating substrate and performing an
electrochemical deposition process through the conductive foil so
as to fill the through hole with a conductive material along a
direction towards the first surface of the insulating substrate,
thereby preventing the formation of voids in the through hole and
hence reducing the overall resistance and preventing a blister
effect from occurring.
Inventors: |
Wei; Shih-Long; (Hukou
Township, TW) ; Hsiao; Shen-Li; (Hukou Township,
TW) ; Ho; Chien-Hung; (Hukou Township, TW) ;
Lin; Yuan-Chiang; (Hukou Township, TW) ; Kuo;
Chen-Shen; (Hukou Township, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wei; Shih-Long
Hsiao; Shen-Li
Ho; Chien-Hung
Lin; Yuan-Chiang
Kuo; Chen-Shen |
Hukou Township
Hukou Township
Hukou Township
Hukou Township
Hukou Township |
|
TW
TW
TW
TW
TW |
|
|
Assignee: |
Viking Tech Corporation
Hukou Township
TW
|
Family ID: |
49620744 |
Appl. No.: |
13/564673 |
Filed: |
August 1, 2012 |
Current U.S.
Class: |
205/135 |
Current CPC
Class: |
H05K 1/0306 20130101;
H05K 2201/09563 20130101; H05K 3/426 20130101 |
Class at
Publication: |
205/135 |
International
Class: |
C25D 5/02 20060101
C25D005/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2012 |
TW |
101118471 |
Claims
1. A method for fabricating a conductive structure of a substrate,
comprising the steps of: providing an insulating substrate having
opposite first and second surfaces and forming an insulating
adhesive film on the second surface of the insulating substrate;
forming at least a through hole penetrating the insulating
substrate and the insulating adhesive film and forming a conductive
foil on the insulating adhesive film so as to cover the through
hole; and forming a shielding material on the conductive foil and
the second surface of the insulating substrate and performing an
electrochemical deposition process through the conductive foil so
as to fill the through hole with a conductive material along a
direction towards the first surface of the insulating
substrate.
2. The method of claim 1, further comprising removing the shielding
material, the conductive foil and the insulating adhesive film and
planarizing the first and second surfaces of the insulating
substrate so as for the conductive material to be flush with the
first and second surfaces of the insulating substrate.
3. The method of claim 2, further comprising forming circuit layers
on the first and second surfaces of the insulating substrate,
respectively, the circuit layers being electrically connected
through the conductive material.
4. The method of claim 1, wherein filling the through hole with the
conductive material comprises isotropically and uniformly
depositing the conductive material in the through hole from the
conductive foil to the first surface.
5. The method of claim 1, wherein the insulating substrate is an
aluminum nitride substrate or an aluminum oxide substrate.
6. The method of claim 1, wherein the insulating adhesive film is
an acid-resistant acrylic thermosetting adhesive film.
7. The method of claim 1, wherein the conductive foil is made of
copper.
8. The method of claim 1, wherein the shielding material is an
anti-plating adhesive tape or a gasket.
9. The method of claim 1, wherein the conductive material is made
of copper.
10. The method of claim 1, wherein the through hole has a diameter
greater than 300 um.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to methods for fabricating
conductive structures of substrates, and more particularly, to a
method for filling a conductive material in a through hole of a
substrate.
[0003] 2. Description of Related Art
[0004] To form a conductive structure in a substrate, a method as
disclosed by Taiwan Patent No. 540,279 can be performed. First, at
least a though hole is formed in the substrate. Then, a conductive
layer is formed on the entire surface of the substrate by
sputtering, and a dry film is attached to the conductive layer and
patterned by exposure and development. Subsequently, an
electroplating process is performed by using the conductive layer
as a current conductive path, thereby filling the through hole with
a conductive material and forming a circuit layer on the
substrate.
[0005] However, during the electroplating process, the through hole
is filled with the conductive material from the sidewall towards
the center. Therefore, the through hole may be not completely
filled. Consequently, voids may be formed in the conductive
material of the through hole, thus increasing the overall
resistance and decreasing the conductivity of electrical signals.
Moreover, voids may expand in a high temperature environment so as
to cause a blister effect.
[0006] Further, to avoid the formation of voids in the through
hole, the conductive material deposited on the surface of the
substrate and around the through hole is required to have a big
thickness. As such, a thick circuit layer is formed, which leads to
an increased thickness of the final product and an increased
thermal resistance in a direction perpendicular to the
substrate.
[0007] Furthermore, the circuit layer usually has a dimple formed
at or close to the position of the through hole, thus resulting in
an uneven surface of the circuit layer and hence adversely
affecting a subsequent die bonding process. To overcome the
drawback, the die bonding process is performed at a position far
from the dimple, which, however, reduces the utilization rate of
the substrate surface and increases the cost.
[0008] Therefore, there is a need to provide a method for
fabricating a conductive structure of a substrate so as to overcome
the above-described drawbacks.
SUMMARY OF THE INVENTION
[0009] In view of the above-described drawbacks, the present
invention provides a method for fabricating a conductive structure
of a substrate, which comprises the steps of:
[0010] providing an insulating substrate having opposite first and
second surfaces and forming an insulating adhesive film on the
second surface of the insulating substrate; forming at least a
through hole penetrating the insulating substrate and the
insulating adhesive film and forming a conductive foil on the
insulating adhesive film so as to cover the through hole; and
forming a shielding material on the conductive foil and the second
surface of the insulating substrate and performing an
electrochemical deposition process through the conductive foil so
as to fill the through hole with a conductive material along a
direction towards the first surface of the insulating
substrate.
[0011] In an embodiment, after the through hole is filled with the
conductive material, the shielding material, the conductive foil
and the insulating adhesive film can be sequentially removed, and
the first and second surfaces of the insulating substrate can be
planarized so as for the conductive material to be flush with the
first and second surfaces of the insulating substrate. Then,
circuit layers can be formed on the first and second surfaces of
the insulating substrate, respectively, and electrically connected
through the conductive material.
[0012] Therefore, by performing an electrochemical deposition
process through the conductive foil formed on the insulating
adhesive film and covering the through hole, the present invention
can fill the through hole with the conductive material in a
longitudinal direction so as to avoid the formation of voids in the
through hole. Further, since the circuit layers can be formed after
planarization of the surfaces of the insulating substrate, the
circuit layers can have a reduced thickness and no dimples are
formed in the circuit layers, thereby effectively reducing the
thermal resistance and improving the area utilization.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIGS. 1A to 1K are schematic cross-sectional views showing a
method for fabricating a conductive structure of a substrate
according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] The following illustrative embodiments are provided to
illustrate the disclosure of the present invention, these and other
advantages and effects can be apparent to those in the art after
reading this specification.
[0015] It should be noted that all the drawings are not intended to
limit the present invention. Various modification and variations
can be made without departing from the spirit of the present
invention. Further, terms such as "one", "a" etc. are merely for
illustrative purpose and should not be construed to limit the scope
of the present invention.
[0016] FIGS. 1A to 1K are schematic cross-sectional views showing a
method for fabricating a conductive structure of a substrate
according to the present invention.
[0017] Referring to FIGS. 1A and 1B, an insulating substrate 1
having a first surface 10 and a second surface 11 opposite to the
first surface 10 is provided, and an insulating adhesive film 2 is
formed on the second surface 11 of the insulating substrate 1. The
insulating substrate 1 can be an aluminum nitride substrate or an
aluminum oxide substrate.
[0018] Referring to FIGS. 1C and 1D, a single or a plurality of
through holes 3 are formed to penetrate the insulating substrate 1
and the insulating adhesive film 2, and a conductive foil 4 is
formed on the insulating adhesive film 2 for covering the through
holes 3. The insulating adhesive film 2 can be an acid-resistant
acrylic thermosetting film. The conductive foil 4 can be made of
copper. Each of the through holes 3 can have a diameter greater
than 300 um.
[0019] Referring to FIGS. 1E and 1F, a shielding material 5 is
formed on the conductive foil 4 and the second surface 11, and by
performing an electrochemical deposition through the conductive
foil 4, a conductive material 6 is filled in the through holes 3
along a longitudinal direction towards the first surface 10 of the
insulating substrate 1. The shielding material 5 can be an
anti-plating adhesive tape or a gasket. The conductive material 6
can be made of copper. Filling the through holes 3 with the
conductive material 6 comprises uniformly and isotropically
depositing the conductive material 6 in the through holes 3 from
the conductive foil 4 to the first surface 10.
[0020] In particular, the conductive material is uniformly and
isotropically deposited from the second surface 11 to the first
surface 10 such that the through holes 3 are effectively and
completely filled with the conductive material to thereby obtain a
compact and solid conductive structure. Therefore, the present
invention prevents the formation of voids and consequently
overcomes the conventional drawbacks of high resistance and blister
effect.
[0021] Subsequently, the processes of FIGS. 1G to 1K can be
selectively performed.
[0022] Referring to FIGS. 1G to 1J, the shielding material 5, the
conductive foil 4 and the insulating adhesive film 2 are
sequentially removed, and then the first surface 10 and the second
surface 11 are planarized simultaneously or sequentially. As such,
portions of the conductive material 6 protruding above the through
holes 3 are removed so as for the conductive material 6 to be flush
with the first and second surfaces 10, 11. The planarization
process can be realized by grinding or sandblasting.
[0023] Referring to FIG. 1K, circuit layers 7, 8 are formed on the
first surface 10 and the second surface 11, respectively, and
electrically connected through the conductive material 6 in the
through holes 3. The circuit layers 7, 8 can be formed by using
such as lithography technologies for forming certain patterns or
electrochemical technologies for forming circuit layers. Since
related technologies are well known in the art, detailed
description thereof is omitted herein.
[0024] According to the present invention, the circuit layers are
fabricated after the through holes are filled with the conductive
material. That is, the hole filling process and the circuit layer
fabricating process are performed separately such that the circuit
layers can have a reduced thickness so as to reduce the thermal
resistance. Further, the surfaces of the substrate are planarized
together with the conductive material so as to prevent the
formation of dimples in the circuit layer, thereby effectively
increasing the die bonding area.
[0025] Further, compared with the conventional conductive through
holes that generally have a diameter not more than 150 um, the
through holes of the present invention have a diameter greater than
300 um and consequently the conductive through holes formed by
filling the through holes with the conductive material have a
larger diameter and correspondingly larger area. According to the
relationship between area and resistance, each conductive through
hole of the present invention is equivalent to four conventional
through holes, thus saving the laser processing time and reducing
the fabrication cost.
[0026] In addition, since the conductive through holes of the
present invention have a large diameter and no dimple is formed in
the circuit layers, technologies for forming thermal vias in the
conductive through holes are applicable in the present
invention.
[0027] The above-described descriptions of the detailed embodiments
are only to illustrate the preferred implementation according to
the present invention, and it is not to limit the scope of the
present invention. Accordingly, all modifications and variations
completed by those with ordinary skill in the art should fall
within the scope of present invention defined by the appended
claims.
* * * * *