Microsensor, and packaging method therefor

Details Microsensor, and packaging method therefor Microsensor, and packaging method therefor

1999-12-30

2001-09-04

Bowers, Charles (Department: 2823)

Semiconductor device manufacturing: process

Packaging or treatment of packaged semiconductor

Assembly of plural semiconductive substrates each possessing...

C438S108000, C438S112000, C438S113000

Reexamination Certificate

active

06284567

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a microsensor for use in a microgyroscope, and a packaging method therefor, in which during a bonding packaging operation for the purpose of protecting the microstructure or for the purpose of sealing it, the inside and outside of the packaged microsensor are perfectly connected together without a possibility of short circuit, so that any short circuit of the metal layer of the contact hole can be prevented. Further, the present invention relates to a method for packaging a microsensor, in which a metal deposition layer is continuously formed on the corner where the contact hole of the package wafer and the surface of the device wafer are contacted together, thereby preventing a short circuit of the metal layer of the contact hole.
BACKGROUND OF THE INVENTION
Generally, the conventional microsensor packaging method is carried out in the following manner.
That is, as shown in
FIG. 1
, on the surface of a device wafer
10
(
FIG. 1
a
), an etching (
20
) is carried out at a certain thickness so as to install a structure (
FIG. 1
b
). Then as shown in
FIG. 1
c,
a sacrificial layer
30
is formed by carrying out an etching on the already etched part
20
, thereby completing the device process. Then on the bottom of a separate package wafer
40
(
FIG. 1
d
), an etching is carried out to form a cavity
50
(
FIG. 1
e
). Then a through contact hole
60
is formed on the package wafer
40
as shown in
FIG. 1
f
so as to make it contacted to the device wafer
10
, thereby completing the package wafer process.
Then the protecting package wafer
40
is mounted on the surface of the device wafer
10
by carrying out a bonding step
50
′ as shown in
FIG. 1
g.
Then in order to form patterns on the surface of the device wafer
10
and on the surface of the package wafer
40
, and in order to connect them together, a metal deposition process
70
is carried out on the inside of the contact hole
60
of the package wafer
40
as shown in
FIG. 1
h,
and then, a patterning is carried out, thereby completing the manufacture of the microsensor package.
However, the diameter of the contact hole
60
of the package wafer
40
has to be narrowed according as it is coming down, so that the deposited metal layer
70
would be perfectly continuous in the contact hole
60
. Therefore, the lower portion of the contact hole
60
has to have a sharp corner, but the sharp corner is frequently detached during the manufacturing process or after the manufacture.
In the above described cases, when the metal layer
70
is deposited on the inside of the contact hole
60
, the deposited metal is short-circuited to the surface of the device wafer
10
, with the result that the device shows malfunctions, and thus the device becomes defective.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above described disadvantages of the conventional technique.
Therefore it is an object of the present invention to provide a microsensor in which the corner where the package wafer is connected to the device wafer is provided in the form of a round part, and thus a metal deposition layer is continuously formed at the corner, so that the short circuiting of the metal deposition layer of the contact hole can be prevented, and that the contact hole of the package wafer can be connected to the surface of the device wafer in a sure form.
It is another object of the present invention to provide a method for packaging a microsensor, in which a sand blast is carried out into the contact hole of the package wafer to improve the surface roughness so as to increase the adherence between the deposited metal layer and the package wafer, thereby preventing the peeling of the metal layer during the bonding process.
In achieving the above objects, the method for packaging a microsensor according to the present invention includes the steps of: etching a structure installing part of a device wafer so as to install a structure on a surface of the device wafer, and then, forming a sacrificial layer on the part thus etched (device manufacturing step); forming a cavity in a separate package wafer (package wafer manufacturing step); bonding the package wafer (having a function of protection) onto a surface electrode of the device wafer thus manufactured (wafer bonding step); forming a contact hole in the package wafer, for connecting patterns of the device wafer and the package wafer together (contact hole forming step); and depositing a metal on an inside of the contact hole of the package wafer by applying a sputtering process (metal depositing and patterning step).
In another aspect of the present invention, the microsensor according to the present invention includes: a device wafer with a surface electrode printed thereon; a package wafer bonded on the device wafer to protect the surface electrode of the device wafer; a contact hole formed in the package wafer to connect the surface electrode of the device wafer to a metal pattern of the surface of the package wafer; a round part formed on a corner where the contact hole of the package wafer is connected to the surface electrode of the device wafer; and a metal deposition layer deposited one the inside of the contact hole and on the surface of the package wafer, for a connection to the surface electrode of the device wafer.


REFERENCES:
patent: 5408731 (1995-04-01), Berggvist et al.
patent: 5834334 (1998-11-01), Leedy
patent: 5908719 (1999-06-01), Guckel et al.
patent: 62268147-A (1987-11-01), None
patent: 07335920 (1995-12-01), None
patent: 2000205862-A (2000-06-01), None

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