Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-09-22
2004-08-17
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB, C324S754090
Reexamination Certificate
active
06777968
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-285139, filed Oct. 6, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a probing method and a probing apparatus, and more specifically, to a probing method and a probing apparatus with high reliability, in which a load applied to a main chuck carrying an object of inspection thereon by probes is measured when the main chuck is overdriven to the probes, so that a steady load can always be applied to the main chuck in accordance with the measured value.
As shown in
FIG. 8
, a probing apparatus
10
for checking integrated circuits on a wafer for electrical properties, for example, is provided with a loading chamber
11
, probing chamber
12
, controller
13
, and display unit
14
. In the loading chamber
11
, wafers W stored in a cassette C are delivered one after another and transported to the probing chamber
12
. The probing chamber
12
adjoins the loading chamber
11
. Integrated circuits formed on each wafer W that is transported from the loading chamber
11
are inspected in the probing chamber
12
. The controller
13
controls the chambers
11
and
12
. The display unit
14
doubles as a control panel for operating the controller
13
.
The loading chamber
11
is provided with a pair of tweezers
15
for use as a transportation mechanism for the wafers W. The tweezers
15
moves back and forth in the horizontal direction and rotates forward and reversely, thereby delivering the wafers W in the cassette C one after another and transporting them into the probing chamber
12
. A sub-chuck
16
for pre-aligning each wafer W is provided near the tweezers
15
. As the sub-chuck
16
receives each wafer W from the tweezers
15
and rotates in the forward direction and the reverse direction in a &thgr;-direction, it pre-aligns the wafer W on the basis of its orientation flat.
The probing chamber
12
is provided with a main chuck
17
that carriers each wafer W thereon. The main chuck
17
is moved in X- and Y-directions by means of X- and Y-stages
18
,
19
, respectively, and moved in Z- and &thgr;-directions by means of built-in drive mechanisms. Alignment means
20
is provided in the probing chamber
12
. The alignment means
20
serves to align each wafer W with the probes. The alignment means
20
includes an alignment bridge
22
having first image-pickup means (e.g., CCD camera)
21
for imaging the wafer W a pair of guide rails
23
for guiding the bridge
22
in reciprocation in the Y-direction, and second image-pickup means (e.g., CCD camera, not shown) attached to the main chuck
17
. A probe card is provided on the top surface of the probing chamber
12
. On the upper surface of the probe card, a test head is connected electrically to the card by means of a connecting ring. A test signal from a tester
34
(see
FIG. 1
) is transmitted to the probe card via the test head and the connecting ring, and further transmitted from the probe card to the wafer W. The object of inspection is checked for electrical properties in accordance with the test signal.
In inspecting the integrated circuits formed on each wafer W, the tweezers
15
takes out one of the wafers W from the cassette C. While the wafer W is being transported to the probing chamber
12
, it is pre-aligned on the sub-chuck
16
. Thereafter, the tweezers
15
delivers the wafer W to the main chuck
17
in the probing chamber
12
. The alignment bridge
22
moves to the center of the probe card. The main chuck
17
moves to the position under the first image-pickup means
21
of the bridge
22
, and the wafer on the chuck
17
is aligned with the probe card by means of the first image-pickup means
21
and the second image-pickup means. As the main chuck
17
moves in the X- and Y-directions, the wafer W is subjected to index feed. As the chuck
17
ascends in the Z-direction, the electrodes of the integrated circuits are brought into contact with probes. When the main chuck
17
is overdriven, the integrated circuits on the wafer W are checked for electrical properties with their electrodes electrically in contact with the probes.
In the case of a wafer W with a diameter of 200 mm or less, as shown in
FIG. 9A
, the wafer W on the main chuck
17
ascends from the position indicated by dashed line to the position indicated by full line as the main chuck
17
is overdriven. As indicated by full line in
FIG. 9A
, the wafer w rises in the Z-direction without substantially tilting from its horizontal position. As this is done, each probe
24
A of a probe card
24
is elastically raised from the position of dashed line to the position of full line of FIG.
9
A. The tip of the probe
24
A moves from a starting point S to an ending point E, as indicated by thick line. The plane distance covered by the tip that moves from the starting point S to the ending point E, as indicated by hatched arrow in
FIG. 9B
, is within the area of an electrode pad P of each integrated circuit. Thus, the probe
24
A and the electrode pad P are brought electrically into contact with each other, whereupon the integrated circuit is inspected.
In the case of a wafer W with a diameter of 300 mm, the wafer size is too large, and besides, the integrated circuits are hyperfine, and electrode pads are arranged at narrow pitches. The number of pins of the probe card is increased (e.g., to 2,000) correspondingly. A load from about 2,000 probes
24
A that acts on the main chuck
17
when the chuck is overdriven is as heavy as, for example, more than 10 kg to 20 kg. Accordingly, an unbalanced load that is generated when the wafer w is overdriven from the position indicated by dashed line in
FIG. 10A
so that it touches the probes
24
A causes the rotating shaft (not shown) of the main chuck
17
to bend. In consequence, the wafer W is tilted for about 20 to 30 &mgr;m, for example, as indicated by full line in
FIG. 10A
, and deflected outward from its original raised position. As this is done, the tip of each probe
24
A is elastically raised from the position indicated by dashed line to the position indicated by full line of
FIG. 10A
, and moves along a track (indicated by thick line in
FIG. 10A
) that is longer than the one shown in FIG.
9
A. Although the starting point S of the tip is situated in the same position as the one shown in
FIG. 9A
, the ending point E is located outside the area of the electrode pad P, as indicated by hatched arrow in FIG.
10
B. Thus, test signals cannot be transmitted from the probes
24
A to the electrode pads P, so that the reliability of the inspection is lowered.
In Jpn. Pat. Appln. KOKAI Publication No. 11-30651, the inventor hereof proposed a probing method and a probing apparatus in which dislocation of probes attributable to contact load is corrected three-dimensionally. According to this technique, the probes estimate a distortion of a main chuck in the position where the probes are in contact with a wafer, in accordance with known data, such as information (outside diameter, material, etc.) on the main chuck, information (outside diameter, number of chips, etc.) on the wafer, and information (probe tip area, number of probes, etc.) on a probe card. Based on the estimated value, the position where the probes are in contact with the wafer is corrected three-dimensionally.
BRIEF SUMMARY OF THE INVENTION
According to the probing method and the probing apparatus described in Jpn. Pat. Appln. KOKAI Publication No. 11-30651, a load (needle pressure) in the contact position of the probes is estimated in accordance with the contact position for overdrive operation and a given overdrive, the distortion of the main chuck is estimated according to the estimated load, and the contact position of the probes is three-dimensionally corrected in accordance with the estimated distortion. If the estimated load and an actual load are inconsistent, therefore, the three-dimensional
Ishii Kazunari
Kobayashi Masahito
Cuneo Kamand
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Patel Paresh
Tokyo Electron Limted
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