Abrading – Precision device or process - or with condition responsive... – With indicating
Utility Patent
1999-05-18
2001-01-02
Rose, Robert A. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S403000, C451S388000, C451S451000, C134S902000, C134S104100
Utility Patent
active
06168499
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a grinding apparatus for semiconductor wafers, and more particularly, to a grinding apparatus for grinding semiconductor wafers while measuring the thickness of the wafers using a height gauge.
2. Description of the Related Art
In semiconductor device fabrication, a plurality of chips are formed on the wafer by carrying out various processing steps using a deposition facility, a diffusion facility, and an etching facility, etc. The wafer having a plurality of chips formed thereon is moved to an Electrical Die Sorting (EDS) facility for the EDS process, wherein the chips on the wafer go through a test to determine whether the chips are normal or abnormal, and abnormal chips are repaired.
In addition, the wafers after completing the EDS process, are moved to a back-grinding apparatus and a back-grinding process is carried out so as to grind the back side of the wafer to a certain thickness.
FIG. 1
is a plan view schematically showing a conventional back-grinding apparatus to grind the back side of the wafer,
FIG. 2
is a schematic representation showing the configurations of a first height gauge, a second height gauge, a grinder, and a cooling water supply installed on the rough-grinding region and the fine-grinding region on the table depicted in
FIG. 1
, and
FIG. 3
shows the height gauge shown in FIG.
1
.
The conventional grinding apparatus for semiconductor wafers includes a round table
10
, which is able to rotate 90° in any one direction. The table
10
is divided into a pie-shaped loading region
12
, a rough-grinding region
14
, a fine-grinding region
16
, and a unloading region
18
. On each region
12
,
14
,
16
,
18
on the table
10
, there is a spin-chuck
20
to suction-fix a wafer
2
and be rotated at a certain speed. On the upper surface of the spin-chuck
20
, there are formed a plurality of vacuum holes (not shown), and through the plurality of vacuum holes, the air around the spin-chuck
20
is pumped inside the spin-chuck
20
so that the wafer
2
is suction-fixed on the spin-chuck
20
.
In addition, as shown in
FIG. 2
, on the upper side of the spin-chuck
20
provided on the rough-grinding region
14
and the fine-grinding region
16
on the table
10
, there is provided a grinder
30
, which contacts the wafer
2
being suction-fixed on the spin-chuck
20
, rotates, and grinds the wafer
2
. On the lower side of the grinder
30
, there is provided a diamond disk
32
. In addition, on one side of the grinder
30
, there is provided a cooling water supply
34
to supply cooling water between the wafer
2
and the diamond disk
32
of the grinder
30
.
Around the rough-grinding region
14
and the fine-grinding region
16
of the table
10
, there are provided a first height-gauge
4
and a second height-gauge
6
. The first height-gauge
4
measures a vertical distance (now referred to as a first vertical distance) from a standard point (not shown) under the spin-chuck
20
to the upper surface of the wafer
2
by locating a contact head
46
on the wafer
2
fixed on the spin-chuck
20
, and the second height gauge
6
measures a vertical distance (now referred to as a second vertical distance) from the standard point to the upper surface of the spin-chuck
20
by locating the contact head
46
on the spin-chuck
20
. As shown in
FIG. 3
, there is provided a cube-shaped bed
40
on the first height-gauge
4
and the second height-gauge
6
.
A certain amount of oil (not shown) is contained inside the bed
40
in order to maintain the inner temperature of the bed
40
at a specific degree, and prevent the corrosion of the inside of the bed
40
. There is provided a piston
42
on the lower side of the bed
40
, and there is provided a finger
44
on the end of the piston with the contact head
46
fixed thereon so as to move up and down. In addition, on the connection point of the piston
42
and the finger
44
, there is provided a first connection body
48
, which is able to move up and down according to the up/down movement of the finger
44
. The first connection body
48
and a differential transformer
54
inside the bed
40
are connected by a second connection body
50
, and so, up/down movement of the first connection body
48
is transmitted to the differential transformer
54
through the second connection body
50
. The first connection body
48
is connected with the second connection body
50
through a through hole (not shown) formed in a rubber piece
52
provided on the side wall of the bed
40
. The differential transformer
54
outputs an electrical signal according to the movement of the second connection body
50
connected with the first connection body
48
to the outside so as to measure the vertical distance from the standard point to the end of the contact head
46
. As described above, the height gauges
4
,
6
are well-known to those skilled in the art, and commercially widespread.
The wafer
2
is mounted on spin-chuck
20
installed on the loading region
12
of the table
10
by a transfer means with its upper side turned down, the air around the spin-chuck
20
is pumped to the inside of the spin-chuck
20
through the vacuum holes formed on the upper surface of the spin-chuck
20
, and the wafer
2
is suction-fixed on the spin-chuck
20
.
Then, with the table
10
rotating 90° in one direction, the wafer
2
on the loading region
12
of the table
10
is moved to the rough-grinding region
14
of the table
10
. Then, the contact head
46
of the first height gauge
4
is placed on the wafer
2
of the rough-grinding region
14
, and the contact head
46
of the second height gauge
6
is placed on the spin-chuck
20
of the rough-grinding region
14
.
Therefore, each finger
44
of the first height gauge
4
and the second height gauge
6
is moved up and down, and with the up/down movement of the finger
44
, the first connection body
48
and the second connection body
50
are moved. With the movement of the second connection body
50
, each differential transformer
54
inside the bed
40
of the first height gauge
4
and the second height gauge
6
outputs an electrical signal according to the movement of the second connection body
50
to the outside.
Accordingly, the first vertical distance and the second vertical distance are measured, and the wafer thickness is measured by obtaining the difference between the first vertical distance and the second vertical distance.
Then, the grinder
30
is moved down such that the wafer
2
fixed on the spin-chuck
20
of the rough-grinding region
14
of the table
10
, and the diamond disk
32
of the grinder
30
, are brought into contact.
Then, the back side of the wafer
2
is ground according to the rotation of the grinder
30
and the spin-chuck
20
, and while the grinding process goes on, the cooling water supply
34
supplies cooling water between the wafer
2
and the diamond disk
32
of the grinder
30
thereby preventing overheating due to the abrasion between the wafer
2
and the diamond disk
32
, and cleaning the silicon powder generated grinding the wafer.
During the grinding process, the first height gauge
4
and the second gauge
6
continuously measure the thickness of the wafer
2
, and if the wafer is ground down to a desired thickness set by the thickness measurement, the spin-chuck
20
and the grinder
30
stop their rotation.
Then, while the table
10
rotates 90° in one direction, the wafer
2
on the rough-grinding region
14
of the table
10
is moved to the fine-grinding region
16
, and the grinding process is carried out in the fine-grinding region
16
in the same manner as in the rough-grinding region
14
, i.e., the thickness of the wafer
2
is measured using the first height gauge
4
and the second height gauge
6
around the fine-grinding region
16
, and the back side of the wafer
2
is precisely fine-ground to a certain thickness using another grinder on the upper side of the fine-grinding region
16
.
While the wafer
2
is fine-gr
Jones Volentine, LLC
Rose Robert A.
Samsung Electronics Co,. Ltd.
LandOfFree
Grinding apparatus for semiconductor wafers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Grinding apparatus for semiconductor wafers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Grinding apparatus for semiconductor wafers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525499