Measuring and testing – Inspecting
Reexamination Certificate
2000-09-28
2003-10-21
Noland, Thomas P. (Department: 2856)
Measuring and testing
Inspecting
C073S865900, C324S765010
Reexamination Certificate
active
06634245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mechanism for rotating a chuck top on which an object to be inspected is mounted and to a mount mechanism on which the object is mounted. More specifically, the present invention relates to a rotating mechanism and an object mount mechanism which reliably prevents the chuck top from being shifted in the &thgr; direction, and which reliably prevents an inspection probe needle from being shifted from the right inspection position on the object.
2. Discussion of the Background
A conventional probing apparatus for inspecting the electrical characteristics of integrated circuits (ICs) formed on a semiconductor wafer (hereinafter referred to as a wafer) is provided with a loading chamber
1
and a probing chamber
2
, as shown in
FIGS. 7 and 8
. The loading chamber
1
is a chamber through which the wafer w is transported for pre-alignment, and the probing chamber
2
is a chamber in which the electrical characteristics of the IC formed on the wafer W transported from the loading chamber
1
are inspected. As shown in
FIG. 8
, a tweezers
3
and a subchuck
4
, which jointly constitute a transport mechanism, are arranged in the loading chamber
1
. The wafer w is transported by the trawzeers
3
and is pre-aligned on a sub-chuck
4
with reference to an orientation flat or a notch. Arranged inside the probing chamber
2
are a main chuck
5
on which the wafer w to be inspected is mounted, and an alignment mechanism
6
which is provided with a vertically-movable camera. Under the alignment mechanism
6
, the main chuck
5
is moved in the X, Y, Z and &thgr; directions, so that the electrodes of the ICs formed on the wafer W are aligned with the probe needles
7
A of a probe card
7
. After the alignment, the electrical characteristics of the IC are inspected by a test head T in the state where the electrodes of the IC formed on the wafer of the main chuck
5
are kept in electric contact with the probe needles
7
A. The main chuck
5
contains a temperature-adjusting mechanism. By this mechanism the temperature of the wafer W is kept in a relatively wide range (e.g., −50° C. to +160° C.), and a normal-temperature test, a low-temperature test, and a high-temperature test are conducted.
When the electrical characteristics of ICs formed on the wafer W are inspected, the wafer w is placed on the main chuck
5
, and the temperature of this main chuck
5
is kept at a predetermined value by the temperature-adjusting mechanism. By the alignment mechanism
6
, the electrodes of the ICs formed on the wafer W are aligned with the probe needles
7
A. Thereafter, the main chuck
5
is raised in the Z direction until the electrode pads of the ICs formed on the wafer W are brought into electric contact with the probe needles
7
A. In this state, the electrical characteristics of the ICs are inspected by the test head T. The probe card
7
is removably provided on a head plate
8
, which is a top plate of the probing chamber
2
.
As shown in
FIG. 9
, the main chuck
5
is provided with: a chuck top
5
A, a support table
5
B for supporting the chuck top
5
A, and a ring-like bearing
5
C arranged between the chuck top
5
A and the support table
5
B and having a cross roller. By means of a rotating mechanism shown in
FIGS. 10 and 11
, the chuck top SA is rotatable on the support table
5
B, with the bearing
5
C interposed. It is rotatable in the &thgr; direction normally and reversely. The rotating mechanism
8
,
9
, which is shown in
FIGS. 10 and 11
, is coupled to the chuck top
5
A of the main chuck
5
, and the chuck top
5
A is rotated in the &thgr; direction normally and reversely.
The rotating mechanism
8
shown in
FIG. 10
includes a motor
8
A, a ball screw
8
B coupled to the motor
8
A, a nut
8
C which is in engagement with the ball screw
8
B, and a belt
8
D which connects the nut
8
C and the chuck top
5
A in a crossed state. The rotating mechanism
8
rotates the chuck top
5
A by means of the belt
8
D in accordance with the movement of the nut
8
C, and the chuck top
5
A is rotated normally and reversely in the direction indicated by arrow &thgr;
1
.
The rotating mechanism shown in
FIG. 11
includes a motor
9
A, a ball screw
9
B coupled to the motor
9
A, a nut
9
C which is in engagement with the ball screw
9
B and coupled to the chuck top
5
A, and a support member
9
D for supporting the ball screw
9
B. When the ball screw
9
B is rotated, the nut
9
C moves in the A directions. In accordance with this movement of the nut
9
C, the chuck top
5
A is rotated normally and reversely in the direction indicated by arrow &thgr;
1
.
SUMMARY OF THE INVENTION
In accordance with the development of ultrafine integrated circuits formed on semiconductor wafer, electrode pads are arranged at narrower pitches, and the number of ICs measured at a time is increasingly large. Under the circumstances, the number of probe needles
7
A used in the measurement is increasingly large. Due to the use of a large number of probe needles
7
A, the total pressure exerted on the semiconductor wafer through the probe needles
7
A is very high since the pressure exerted on an electrode pad of the semiconductor wafer by one probe remains the same. In particular, when an ICs formed on the periphery of a wafer W is inspected, a needle pressure as large as several kg is applied to the chuck top
5
A as an eccentric load, as indicated by the arrow in FIG.
9
. In general, the outer diameter of the ring-like bearing
5
C is very small in comparison with the outer diameter of the chuck top
5
A or support table
5
C, and there is a gap in the areas outward of the ring-like bearing
5
C. The eccentric load exerted on the chuck top
5
A elastically deforms the bearing though slightly, and the chuck top
5
A slants, as indicated exaggeratedly with the one-dot-dash line in FIG.
5
A. As a result, the probe needles
7
A are shifted from the desirable alignment positions, and the reliability of the inspection is significantly lowered.
Where the wafer size is large in diameter, the distance between the center of the main chuck
5
and the point of action is long in comparison with the corresponding distance of the prior art, thus resulting in a more marked slant of the main chuck
5
. In addition, the pressures applied from the probe needles
7
A may significantly differ, and some of the probe needles
7
A may not be in contact with the electrode pads of the ICs formed on the wafer W. Thus, the reliability of the inspection is markedly degraded.
The rotating mechanism
8
shown in
FIG. 10
is coupled to the chuck top
5
A by means of the belt
8
D. With this structure, the chuck top
5
A is not very rigid in the &thgr;
1
direction. When the main chuck
5
is overdriven, the eccentric load which is applied to the chuck top
5
A when the wafer and the probe needles are brought into contact rotates the chuck top in the &thgr; direction, resulting in a positional shift. By this positional shift, the reliability of the inspection is adversely affected.
In the rotating mechanism
9
shown in
FIG. 11
, the ball screw
9
B swings in the &thgr;
2
direction with the support member
9
D as a center. With this structure, the rotating mechanism
9
is not very rigid in the &thgr;
2
direction, and extra space is needed for the ball screw
9
B to swing. At the present time, more and more ultrafine chips are developed, and more and more large-diameter wafers are developed. Under the circumstances, there is an urgent demand for a solution to the above problems.
To solve the problems described above, the present invention is intended to provide a mechanism for mounting an object to be inspected, which enables the main chuck to be kept in the horizontal state at all times, even if an eccentric load is exerted in the neighborhood of the outer periphery of the chuck top, thereby enhancing the reliability of the inspection.
The present invention is also intended to provide a rotating mechanism and an object mount mechanism
Akaike Yutaka
Iino Shinji
Suzuki Masaru
Yoshioka Haruhiko
Noland Thomas P.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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