Abrading – Machine – Combined
Reexamination Certificate
2000-01-26
2001-11-27
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Combined
C451S056000, C451S296000
Reexamination Certificate
active
06322429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to chemical mechanical polishing. More specifically, the present invention provides a conditioner assembly and conditioner back support for a chemical mechanical polishing apparatus. Moreover, the present invention provides a method for conditioning a polishing pad of a chemical mechanical polishing apparatus by employing the conditioner assembly and the conditioner back support of the present invention.
2. Discussion of the Background
Sub-micron integrated circuit devices are formed on substrates such as semiconductor wafers by patterning conductive or interconnect film layers (e.g., aluminum (Al), copper (Cu), etc.) which have been deposited on nonconductive or intermediate dielectric film layers (e.g., silicon oxide (SiO
x
)). In order to pattern or etch the interconnect film layer, the exposed surface of the interconnect film layer must be topographically planar. An intermediate dielectric film layer having a non-planar surface will transfer its topographical profile to that of the deposited interconnect film layer. As a result, prior to the deposition of the interconnect film layer, the surface of the intermediate dielectric layer has to be planarized. To pose the problem more concretely, the patterning and etching step is prepared by selectively developing photoresist layers on the exposed surface of the interconnect film layer. A non-planar surface prevents the focusing of a photolithography apparatus on the entire exposed surface of the interconnect film layer for the exposure of the photoresists. As a result, the interconnect film layer having a surface defined by a non-planar topography cannot be etched or patterned by photolithographic techniques. The syllogism follows that the intermediate dielectric film layer, on which the interconnect film layer is deposited, must have a planarized surface.
Chemical mechanical polishing (CMP) is one recognized method of planarization. CMP technique requires that the substrate be mounted on a polishing head with the surface of the substrate to be polished exposed. The polishing head, supporting the substrate, is then placed against a polishing pad of a linear polishing belt or a planar polishing pad. Referring to
FIGS. 50 and 51
, which are schematic side elevational and front plan views of a linear CMP apparatus, generally illustrated as
300
, there is seen a continuous, vertical polishing belt
302
configured to polish a vertically held substrate, such as a semiconductor wafer
305
. A polishing head
301
positions the substrate
305
against a polishing pad
304
, which is attached to the vertical polishing belt
302
. The polishing belt
302
is kept in continuous motion, as indicated by arrow
308
, by rotating pulleys
310
and
312
at a selected polishing speed (e.g., 1-10 meters/second). A support head
314
provides a base for the application of pressure (e.g., 1-10 PSI) by the polishing head
301
against the substrate
305
. The polishing head
301
rotates in a clockwise or counter-clockwise direction, as indicated by arrow
316
, and is oscillated back and forth, as indicated by arrow
320
, by an oscillating arm
318
of a driving mechanism (omitted from the Figures). Moreover, a slurry, typically a mixture of an abrasive and at least one chemically reactive agent, is supplied to the polishing pad
304
. Accordingly, a chemical reaction and a mechanical abrasion is provided at an interface between the substrate
305
and the polishing pad
304
.
A planar CMP apparatus
400
, as illustrated in
FIGS. 52 and 53
includes the polishing head
301
, horizontally supporting the substrate
305
. The polishing head
301
, as mentioned above, rotates in a clockwise or counterclockwise direction, as indicated by the arrow
316
, and is oscillated back and forth, as indicated by the arrow
320
, by the oscillating arm
318
of the driving mechanism (omitted from the Figures). However, in lieu of the continuous, vertical polishing belt
302
, a rotating, planar polishing platen
402
is provided. The planar polishing platen
402
supports and rotates the polishing pad
304
about a driving shaft
406
. The rotation of the polishing platen
402
is indicated by arrow
408
. The slurry is provided to the polishing pad
304
for providing the abrasive chemical solution.
The various motions of the different components of the above-discussed linear
300
and planar
400
CMP apparatus often lead to excessive wear near the center of the polishing pad
304
and less wear in the periphery. Consequently, non-uniformity is introduced through the polishing pad
304
into the intermediate dielectric film layer. To maintain uniformity in the polishing of the exposed surface of the intermediate dielectric film layer and to provide reproducibility of the polishing process, the polishing pad
304
, which is typically a polyurethane pad, is required to be conditioned between or during use. Conditioning is necessary to maintain the uniformity of the polishing pad's
304
texture and profile.
SUMMARY OF THE INVENTION
The present invention provides a conditioner assembly for conditioning a polishing pad of a chemical mechanical polishing device. The conditioner assembly comprises a conditioning head having a gimbal assembly, a shaft engaged to the conditioning head, and a linear torque bearing assembly slidably receiving the shaft. The linear torque bearing assembly is configured to operatively rotate the shaft assembly contemporaneously with allowing the shaft to extend and retract from a first open end of the linear torque bearing assembly. The conditioner assembly additionally comprises a bellows secured over the first open end and engaged to the conditioning head. A bearing housing is disposed over a second open end of the linear torque bearing assembly. The bearing housing rotatably supports the linear torque bearing assembly such that a motor assembly can operatively drive the linear torque bearing assembly, the shaft, and the conditioning head.
The present invention also broadly provides a method for conditioning a moving polishing pad of a polishing apparatus (e.g., a chemical mechanical polishing apparatus), wherein the polishing pad is moving in a first direction, comprising:
a) providing a conditioner assembly comprising a conditioning head assembly supporting a conditioning pad, a shaft assembly supporting the conditioning head assembly, and a linear torque bearing assembly slidably receiving the shaft assembly, wherein the linear torque bearing assembly is configured to operatively rotate the shaft assembly;
b) applying a compressive pressure by the conditioning pad to the polishing pad;
c) rotating the linear torque bearing assembly to operatively rotate the conditioning head; and
d) oscillating the conditioner assembly in a second direction different from the first direction to condition the moving polishing pad.
In conditioning the polishing pad, the compressive pressure applied to the polishing pad can be adjusted without stopping the rotation of the linear torque bearing assembly. More specifically, the compressive pressure can be adjusted by increments equal to or greater than 0.1 psi. During the conditioning process, an exposed surface of the conditioning pad will remain generally parallel to and communicating with a plane defined by a surface of the polishing pad.
The present invention additionally provides a conditioner back support which respectively opposes the conditioner assembly such that the polishing belt supporting the polishing pad is disposed intermediate to the conditioner back support and the conditioner assembly. The conditioner back support comprises a frame assembly which adjustably supports a backing plate. The frame assembly comprises a positioning assembly which allows a user to adjust the position of the backing plate. The position of the backing plate can be adjusted such that a front surface of the backing plate is parallel to and disposed on or proximal to a plane defined by a backside of the polishing belt. As a resu
Allen James A.
Can Linh X.
Chang Shou-sung
Fontana Jeffrey M. L.
Jaboneta Jade
Hail III Joseph J.
Mosel Vitelic Inc.
Nguyen Dung Van
Skjerven Morrill & MacPherson LLP
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