Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-08-24
2002-08-13
Le, N. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S765010, C324S1540PB
Reexamination Certificate
active
06433566
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-261106, filed Sep. 14, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a probing method and probing system, and more specifically, a probing method and probing system ensuring an increase of the throughput.
A probing device
10
has a loading (loader) chamber
11
, a probing (prober) chamber
12
, a controller
13
, and a display unit
14
, as shown in FIG.
6
. In the loading chamber
11
, wafers W stored in a cassette C are taken out one by one and transferred to the probing chamber
12
. The probing chamber
12
is adjacent to the loading chamber
11
. The wafer W transferred from the loading chamber
11
is inspected in the probing chamber
12
. The controller
13
controls the probing chamber
12
and the loading chamber
11
. The display unit
14
is also used as an operation panel for controlling the controller
13
.
In the loading chamber
11
, tweezers
15
are provided via a rotary shaft. The tweezers
15
are used for transferring the wafer W. More specifically, the tweezers
15
take out the wafers W stored in the cassette C one by one and transfer them to the probing chamber
12
through back-and-forth movement in a horizontal direction simultaneously with clockwise-and-counterclockwise rotation. A sub-chuck
16
is provided near the tweezers
15
, for prealigning the wafer W. The sub-chuck
16
receives the wafer W from the tweezers
15
and rotates clockwise and counterclockwise in a &thgr; direction, to prealign the wafer W by using an orientation flat of the wafer W as a reference.
The probing chamber
12
has a main chuck
17
for mounting the wafer W thereon. The main chuck
17
is moved in X and Y directions by means of X and Y stages
18
,
19
and further moved in &thgr; and Z directions by built-in driving mechanisms. Furthermore, the probing chamber
12
has an alignment means
20
for aligning the wafer W with a probe card. The alignment means
20
has an alignment bridge
21
which has a first photographic means
21
(CCD camera or the like) for taking a picture of the wafer W, and a pair of guide rails
23
,
23
which guide reciprocal movement of the alignment bridge
22
in the Y direction. A second photographic means (not shown), which is attached to the main chuck
17
, is also included in the alignment means
20
. The probe card (not shown) is provided above the upper surface of the probing chamber
12
. The upper surface of the probe card is electrically connected to a test head (not shown) by way of a connection ring. The probe card receives a test signal from a tester by way of the test head and the connection ring, thereby inspecting electrical characteristics of an IC (formed on the wafer W) in contact with the probe.
More specifically, the IC on the wafer W is inspected as follows: first, a single wafer W is taken out from the cassette C by means of the tweezers
15
within the loading chamber
11
. While the wafer W is transported by the tweezers
15
to the probing chamber
12
, the wafer W is pre-aligned at a sub-chuck
16
. In the probing chamber
12
, the wafer W is passed from the tweezers
15
to the main chuck
17
. Then, the alignment bridge
22
is moved above a probe center to align the wafer W on the main chuck
17
by means of the first photographic means
21
and the second photographic means attached to the main chuck
17
. Thereafter, the wafer W is indexed by moving the main chuck
17
in the X and Y directions. After the main chuck
17
is moved up in the Z direction to allow the wafer W to be in contact with the probe, the main chuck
17
is overdriven. In this manner, each of the IC chips on the wafer w can be electrically in contact with the probe, with the result that electrical characteristics of each of the chips can be checked.
In the case of the wafer W having a size (diameter) of 200 mm or less, when the main chuck
17
is overdriven as shown in
FIG. 7A
, the wafer W mounted on the main chuck
17
is moved up along the z direction from the position indicated by a dash-dotted line to the position indicated by a solid line while being maintained almost horizontal, as shown in a solid line in FIG.
7
A. During this period, the probe
24
A of the probe card
24
is elastically lifted up from the position indicated by a dash-dotted line to the position indicated by a solid line in the FIG.
7
A. The tip of the probe moves from a start point S to an end point E (indicated by a thick solid line). When the movement of the probe tip from the start point S to the end point E is viewed from above, the probe stays within the surface area of the electrode pad P of the IC chip, as shown by an arrow of the hatched line (see FIG.
7
B). Since the probe
24
A can maintain electrical contact with the electrode pad P, the electrical characteristics of the IC chip can be checked precisely.
However, if the size of the wafer is as large as e.g., 300 mm, the IC chip is not necessarily enlarged but miniaturized. Since the pitch between electrode pads is decreased, the number of pins of the probe card is accordingly increased up to about 2000. As a result, the load of the probe
24
A applied on the main chuck
17
during the overdriving time results in, for example, 10 to 20 Kg. When the wafer W is overdriven from the position indicated by a dash-dotted line and comes into contact with the probe
24
A, the load of the probe
24
A is locally applied to the main chuck.
Due to the local application of the load, the rotary shaft (not shown) of the main chuck
17
is distorted, with the result that the wafer W is inclined by about 20-30 &mgr;m, as shown by a solid line in the figure. That is, the wafer W is inclined outward from the position where the wafer W should be moved up. At that time, the tip portion of the probe
24
A is lifted up from the position indicated by a dash-dotted line to the position indicated by a solid line in FIG.
8
A. The moving distance is longer than the case shown in FIG.
7
A. That is, the wafer moves as is indicated by a thick solid line in FIG.
8
A. Although the start point S of the tip portion in this case is the same as that shown in
FIG. 7A
, the end point E is deviated from the electrode pad P as shown by a hatched arrow in FIG.
8
B. Therefore, the tip portion may fall outside the electrode pad P. If this happens, a test signal cannot be sent from the probe
24
A to the electrode pad P. As a result, the inspection will not be performed with high reliability.
The present applicant suggests a probing method and probing device in Japanese Patent Application No. 9-202476 for performing electrical inspection with high reliability by ensuring that a probe is in contact with an electrode pad of a wafer even if a load is locally applied to the main chuck. In this probing method, the correction amounts of the main chuck at the time of overdriving in the X, Y and Z directions are first obtained on the basis of data of the wafer chuck, wafer and probe card. The moving distances of the main chuck in the X, Y, and Z directions are corrected on the basis of the obtained correction amounts. In this way, the main chuck is overdriven.
FIG. 9
shows a system in which servo motors
31
,
32
are employed as an X-axis driving mechanism and a Y-axis driving mechanism for moving a main chuck
17
in the X and Y directions, and a stepping motor
33
is used as a Z-axis driving mechanism for driving the main chuck
17
in the Z-axis. In this system, the stepping motor
33
differs in operational characteristics from the servo motors
31
,
32
. Therefore, it is virtually impossible to start or stop the driving of the servo motors
31
,
32
simultaneously with the stepping motor
33
. Conventionally, the motors
31
,
32
,
33
are independently driven and stopped.
BRIEF SUMMARY OF THE INVENTION
The applicant found that if the X-axis motor, the Y-axis motor, and the Z-axis motor are drive
Inomata Isamu
Kono Isao
Kerveros J
Le N.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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