Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Reexamination Certificate
2003-01-31
2004-07-20
Lee, John R. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
C250S305000, C250S306000, C250S311000, C324S701000
Reexamination Certificate
active
06765203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pallet assembly for substrate inspection device and a substrate inspection device.
2. Description of the Related Art
One of the display devices using a liquid crystal substrate is a flat panel display (hereinafter referred to as an FPD) This FPD is a display device for displaying electronic information. One of the recent typical FPDs is a liquid crystal display (hereinafter an LCD) composed of a thin film transistor (hereinafter a TFT). The LCD composed of the TFT is employed for a high performance laptop computer.
The constitution and the operation of the LCD composed of the TFT will be described below. The LCD composed of the TFT has a fundamental structure of a liquid crystal panel in which a liquid crystal is poured between one glass substrate on which the TFT and pixel electrodes are formed and the other glass substrate on which counter electrodes are formed. In this specification, the one glass substrate on which the TFT and pixel electrodes are formed is defined as a substrate.
FIG. 6
is a schematic view of a substrate on which the TFT and pixel electrodes are formed. In
FIG. 6
, the substrate
10
has a plurality of panels formed on a single glass substrate
11
through a process for manufacturing a typical integrated circuit, each panel
12
being composed of a plurality of pixels
13
arrayed like a matrix.
Each pixel
13
comprises a pixel electrode
14
, a storage capacitor
15
and the TFT
16
. The pixel electrode
14
is formed from a light transmitting material, typically, ITO (Indium Tin Oxide). An electrode having a reference voltage of the pixel
13
applied within the storage capacitor
15
is grounded. Namely, the reference voltage of each TFT
16
is set to a ground level. The TFT
16
functions as a switch. A row selection signal L
R
for switching control is supplied to a gate electrode G of the TFT
16
, and a column selection signal L
C
as the data signal is supplied to a source electrode S of the TFT
16
.
In driving the pixels
13
, when a voltage V
S
is applied to the source electrode S of the TFT
16
(i.e., when the column selection signal L
C
is supplied), if a voltage V
G
is applied to the gate electrode G (i.e., when the row selection signal L
R
is supplied), the TFT
16
is turned on to increase the drain voltage V
D
. At this time, the storage capacitor
15
is charged to maintain a drain voltage V
D
till the next refresh cycle. By repeating this process for each pixel
13
, a liquid crystal molecular array between two glass substrates is controlled to display a two-dimensional image on a liquid crystal display.
In the inspection of the substrate on which the TFT and pixel electrodes are formed, a method for determining a state of each pixel on the substrate without contact, employing the voltage contrast technique of electron beam was proposed U.S. Pat. No. 5,982,190). This substrate inspection method using the voltage contrast technique has the advantages that it is cheaper in the cost than the inspection method using the conventional mechanical probe, and faster in the inspection speed than the optical inspection method.
FIG. 7
is a view for explaining the substrate inspection method using the voltage contrast technique. This inspection method is made within a high vacuum chamber. The substrate to be inspected is conveyed to the high vacuum chamber, and inspected in a state where it is laid on the stage.
In
FIG. 7
, the inspection device comprises an electron beam generating source
21
, a secondary electron detector
24
and a signal analyzer
25
. The electron beam generating source
21
radiates an electron beam
22
to each pixel
13
of the substrate
10
. The secondary electron detector
24
detects a secondary electron
23
generated by radiating the electron beam
22
to each pixel
13
of the substrate
10
. Also, the secondary electron detector
24
outputs a signal representing a voltage waveform of pixel
13
to the signal analyzer
25
on the basis of the detected quantity of secondary electron
23
. The signal analyzer
25
analyzes an output signal from the secondary electron detector
24
to inspect the state of pixel
13
, particularly, the presence or absence or the content of defective pixel. Also, the signal analyzer
25
outputs a drive signal for electrically scanning each pixel
13
on the substrate
10
via a line
26
. This scanning is performed in synchronism with the scanning on the substrate
10
as indicated by the arrow S with the electron beam
22
.
A principle of the voltage contrast technique based on the detected quantity of secondary electron will be described below.
The quantity of secondary electron
23
discharged from each pixel
13
of the substrate
10
depends on an electrode for the voltage of pixel
13
on the substrate
10
. For example, when the pixel
13
of the substrate
10
is driven positively, the secondary electron
23
generated by radiating the electron beam
22
to the pixel
13
has a negative electric charge, and is led into the pixel
13
. As a result, the quantity of secondary electron
23
arriving at the secondary electron detector
24
is decreased.
On one hand, when the pixel
13
of the substrate
10
is driven negatively, the secondary electron
23
generated by radiating the electron beam
22
to the pixel
13
has a negative electric charge, and is repelled against the pixel
13
. As a result, the quantity of secondary electron
23
generated from the pixel
13
arrives at the secondary electron detector
24
.
In this manner, because the detected quantity of secondary electron
23
generated from the pixel
13
is affected by the polarity of voltage of the pixel
13
, a voltage signal waveform of the pixel
13
is measured and the presence or absence of defective pixel is determined.
As above described, the inspection of the substrate is made within the high vacuum environment, and usually within a sealed chamber. Conventionally, this substrate was inspected in the state where it was laid directly on the stage within the chamber. In inspecting the substrate in this situation, the substrate might be broken within the sealed chamber, or a part of the apparatus comprising the chamber might be damaged. Namely, a glass substrate of the substrate might be fractured during the inspection, its fractions being scattered within the chamber to apart of the apparatus comprising the chamber, for example, a turbo molecular pump rotor for vacuum evacuation, damaging the apparatus. Also, it took a lot of trouble to draw back glass fractions scattered within the chamber and over the stage. Thus, it was apprehended conventionally that the apparatus might be damaged due to scattered fractions into the chamber or the withdrawal of fractions was made.
SUMMARY OF THE INVENTION
The present invention has been achieved in the light of the above affairs, and it is an object of the invention to provide a pallet assembly for substrate inspection device and a substrate inspection device for use with this pallet assembly, in which even when the substrate is broken with the inspection device, broken fractions can be easily withdrawn without damaging the inspection device.
In order to achieve the above object, this invention provides a substrate holding pallet assembly comprising a pallet for holding a substrate on upper face thereof, and a probe laid on said pallet from above so as to hold said substrate between said pallet and said probe.
It is preferable that concave grooves that receive conveyance unit for conveying the substrate are formed on the upper face of the pallet. In addition to this, one concave groove may be employed on the pallet.
Also, it is preferable that the pallet comprises a position alignment mechanism for aligning the position of the substrate on the pallet when the substrate is laid.
Also, it is preferable that the pallet comprises an electrode in contact with an external power supply, a feeding portion for applying a voltage from the electrode to a prober, and a flexible circuit
Lee John R.
Rankin, Hill Porter & Clark LLP
Shimadzu Corporation
Vanore David A.
LandOfFree
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