Cleaning and liquid contact with solids – Apparatus – With means to movably mount or movably support the work or...
Reexamination Certificate
2000-04-27
2002-06-18
Stinson, Frankie L. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
With means to movably mount or movably support the work or...
C134S157000, C134S153000, C134S902000
Reexamination Certificate
active
06405739
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a spin chuck used in a chamber, in particular, to a spin chuck capable of providing simultaneous dual-sided processing (including cleaning processes), and capable of widely adjusting the angular velocity and angular acceleration thereof.
BACKGROUND OF THE INVENTION
In a conventional manufacturing process of a semiconductor device or a liquid crystal display (LCD) including wet etching, cleaning, wet spin etching, coating, and developing, various types of acid tanks or chambers are utilized. In a conventional chamber, a wafer or LCD substrate is clamped on a chuck that is driven to rotate by a driving device (e.g. a motor).
A conventional driving system utilizes a single motor as a driving source. A wafer clamped on a chuck is driven to rotate as shown in U.S. Pat. No. 5,312,487.
Referring to
FIG. 1
, a conventional driving system of a spin chuck for driving a substrate
101
to rotate includes a motor
102
, a chuck
104
, and a controller
105
. The motor
102
includes a rotating shaft
103
. The rotating shaft
103
drives the chuck
104
, used to clamp a substrate
101
, to rotate. The controller
105
is used for controlling the angular velocity of the motor
102
. The substrate
101
is clamped on the chuck
104
by way of vacuum pressure. Therefore, the driving system further includes a vacuuming conduit
106
penetrating through the motor
102
.
In the driving system, the chuck
104
is driven by the motor
102
to rotate substrate
101
. The end product of the complicated processes substrate
101
undergoes is determined by the properties of the processing materials, the patterns on the substrate
101
, the angular velocity control and the angular acceleration control of the substrate
101
, among others. After the processing materials and the patterns on the substrate
101
are determined, control over both angular velocity and angular acceleration of the substrate
101
becomes an important issue.
Referring to
FIG. 2
, the horizontal axis represents time, and the vertical axis represents the rotation speed of the substrate. Time t is the time required for the substrate to increase its rotation speed from 0 to N (where N is an integer) rpm (revolutions per minute). A line
107
represents the speed variation of the substrate. Time t is also the time required for the substrate to decrease its speed from 0 to −N rpm. A line
108
represents the speed variation of the substrate. The maximum rotation speed of the substrate is N or −N rpm.
A line
109
represents the rotation speed of the substrate after it reaches N rpm, while a line
110
represents the rotation speed of the substrate after it reaches −N rpm. An area
111
shaded with diagonal lines is the speed variation of the substrate. The maximum angular acceleration of the substrate can be determined from the slopes of lines
107
and
108
.
In general, variations in the angular velocity and the angular acceleration of the motor
102
, which drives the substrate
101
, are ideally as large as possible. However, after the motor
102
is manufactured, the performance (e.g., the maximum instant torque, the maximum rotating speed, the minimum rated rotating speed, the maximum angular acceleration, and related characteristics) of the motor
102
and those of the controller
105
are fixed. When the motor
102
is designed for rotating at high speeds, its rotation condition is not stable or easily controlled at low rotation speeds. In addition, when the motor
102
is designed for rotating at low rotation speeds, its rotation condition is not stable or easily controlled at high rotation speeds.
Recently, the line widths of semiconductor products have greatly decreased. More time is needed for the processing material to fill into the narrow trenches and cover the surfaces of the trenches. After the processing material has filled into the narrow trenches, the redundant processing material cannot be ejected from the trenches due to the surface tension of the processing material. In order to avoid this phenomenon, the driving system has to provide greater angular velocity or angular acceleration to force out the redundant processing material in the trenches.
The design of the motor
102
or controller
105
can be improved to let the angular velocity and the angular acceleration of the motor
102
satisfy the process requirements. However, it is extremely difficult for a single set of one motor
102
and one controller
105
to reach wide controls of angular velocity and angular acceleration, unless the manufacturing costs of the motor
102
and the controller
105
are increased. Even then, a motor
102
and a controller
105
are often unable to satisfy the process requirements.
In a conventional spin chuck driving system, a motor is in direct contact with a chuck. Thus, the heat energy generated from the motor is easily transferred to the chuck, causing the substrate temperature to rise. Furthermore, since the tangential velocity of the circumferential edge of the rotating substrate relative to the air is high, the heat energy at the circumferential edge of the substrate is easily transferred to the air. In addition, since the tangential velocity at the center of the rotating substrate relative to the air is low, the heat energy at the center of the substrate is not easily transferred to the air. As a result, a temperature difference between the circumferential edge and the center of the substrate is induced, which deteriorates the qualities of product.
FIG. 3A
is a front cross-sectional view illustrating a flow status of an etchant on a substrate in a conventional etching process.
FIG. 3B
is a top view illustrating a flow status of an etchant on a substrate in a conventional etching process.
FIG. 3C
is a front cross-sectional view illustrating the etched substrate as shown in FIG.
3
A.
FIG. 3D
is a top view illustrating the etched substrate as shown in FIG.
3
B.
Referring to
FIGS. 3A and 3B
, an etchant
121
flows through a trench
123
of a substrate
122
. An arrow indicates the direction of flow of the etchant
121
. In the prior art, the direction of flow of the etchant
121
is fixed because the rotation direction of the substrate
122
is fixed.
FIGS. 3C and 3D
show the change in the trench patterns and the deteriorating quality of the substrate from the etching process.
In order to prevent the lower surfaces of the wafers or LCD substrates from having direct contact with a spin chuck, a spin chuck using a protective layer of gas and a clamp pin, as disclosed in U.S. Pat. No. 5,421,056, is used. A schematic illustration of the above spin chuck is shown in FIG.
4
A.
Referring to
FIG. 4A
, the spin chuck
141
has six clamp pins
142
. The clamp pins
142
, that clamp or release substrate
140
, form a ring that is adjusted by an extension rod (not shown) and a swingable lever. A supply passage
143
is provided within the spin chuck
141
to support the substrate
140
using a flow of gas. It should be noted that the arrow indicates the gas's direction of flow.
The substrate
140
is not in direct contact with the spin chuck
141
, solving substrate
140
's lower surface pollution problem. However, because there is no relative motion between each of the clamp pins
142
and the substrate
140
, unwanted pin marks
144
are easily formed in the contact regions between each of the clamp pins
140
and the substrate
140
, as shown in FIG.
4
B. Therefore, uniform product quality is not easily obtained.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a spin chuck capable of providing simultaneous dual-sided processing (including cleaning processes), wide ranges of angular velocity and angular acceleration, and uniform substrate quality. The spin chuck in accordance with the invention can rotatably clamp the outer periphery of the substrate so as to provide simultaneous dual-sided processing.
In accordance with an aspect of the invention, a spin chuck used for clamping a substrate to rotate in a
Baker & Daniels
Stinson Frankie L.
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