Coating processes – Coating by vapor – gas – or smoke
Reexamination Certificate
1999-02-08
2001-04-03
Meeks, Timothy (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
C427S099300, C438S679000, C438S680000, C438S758000
Reexamination Certificate
active
06210754
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 87121968, filed Dec. 31, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to integrated circuit (IC) fabrication technology, and more particularly, to a method for use in a chamber used in IC fabrication to adjust for parallel alignment between a shower head and a heater platform in the chamber, so that later the deposition process performed in the chamber can result in an evenly deposited layer on the wafer.
2. Description of Related Art
As IC fabrication technology advances to the submicron level of integration, the fabrication processes become more critical. Any minute errors in the fabrication can lead to a complete failure to the fabricated IC product. Should this be the case, the fabricated IC product may have to be discarded. This makes the IC fabrication quite wasteful and costly to carry out.
Deposition is a highly critical process in IC fabrication. There are two major deposition techniques in IC fabrication: physical-vapor deposition (PVD) and chemical-vapor deposition (CVD).
A deposition process, whether PVD or CVD, is customarily performed in a sealed vacuum chamber. The chamber includes a shower head and a heater platform therein. During the deposition process, the wafer is placed on the heater platform while vapor or gases is applied to the wafer from the shower head. To allow precise fabrication, the shower head and the heater platform should be precisely horizontally-oriented; otherwise, the deposited layer is unevenly dimensioned in thickness.
FIG. 1
is a schematic diagram used to depict a conventional method to achieve the foregoing purpose. As shown, the method of the invention is applied to a chamber
10
having a top cover
12
and a bottom cover
14
(in
FIG. 1
, the top cover
12
is open). A shower head
18
is mounted in the recessed portion
16
on the under side of the top cover
12
, while a heater platform
22
is mounted in the recessed portion
20
of the bottom cover
14
. A pair of level-adjusting devices
24
,
26
, each being composed of a threaded bar and a nut screwed onto the threaded bar, are provided beneath the heater platform
22
, preferably on opposite sides of the heater platform
22
. The technician can manually turn the threaded bars to level the heater platform
22
.
By the conventional method, the top cover
12
is flipped open from the bottom cover
14
, and then several displacement gauges
28
,
30
are placed on the heater platform
22
above the level-adjusting devices
24
,
26
. The technician then manually turns the threaded bars in the level-adjusting devices
24
,
26
while visually checking the level indications from the displacement gauges
28
,
30
until all of them are level. After this, the displacement gauges
28
,
30
are removed, and then the top cover
12
is closed again. At this stage, however, although the heater platform
52
is level, the gap between the shower head
18
and the heater platform
52
may not be even, i.e., the space at one point may be wider than at another point. A solution to this problem is to actually perform a deposition process on a wafer (not shown) placed on the heater platform
52
, and then measure the thickness of the material distributed over the wafer by the deposition process for use as a reference for further adjustment. The deposition and adjustment typically need to be performed several times until the deposited layer is evenly thick over the wafer.
It is apparent that the above-mentioned conventional method is quite laborious to carry out and is also wasteful of wafers. Moreover, since the gap between the shower head
18
and the heater platform
22
is inconsistently fixed in dimension, the fabricated wafers from different chambers are inconsistent in quality.
SUMMARY OF THE INVENTION
It is therefore an objective of the present invention to provide a new adjustment method for the shower head and the heater platform in a chamber, which requires no repetitions in deposition and adjustment, so that the IC fabrication can be more cost-effective than the prior art without having to waste wafers.
It is another objective of the present invention to provide a new adjustment method for the shower head and the heater platform in a chamber, which allows the gap between the shower head and the heater platform to be consistently fixed in dimension, so that the fabricated wafers from different chambers are consistent in quality
In accordance with the foregoing and other objectives of the present invention, a new adjustment method is proposed for use in IC fabrication to adjust for parallel alignment between the shower head and the heater platform in a chamber.
Broadly speaking, the method of the invention includes the following steps: (1) providing a plurality oi level-adjusting devices on the heater platform; (2) providing a plurality of displacement gauges between the heater platform and the shower head, each being located substantially aligned to one of the level-adjusting devices; and (3) adjusting the level-adjusting devices to adjust the leveling of the heater platform until the distance readings from the two displacement gauges substantially reach a predetermined fixed value.
The foregoing method is characterized by the provision of a plurality of displacement gauges between the shower head and the heater platform, with the heater platform being adjusted in such a manner as to allow all the readings from the displacement gauges to be all the same. This not only allows the shower head and the heater platform to be aligned and parallel, but also allows them to be separated by a predetermined, fixed distance. The parallel alignment allows all deposition process subsequently performed in the chamber to provide an evenly deposited layer on the wafer, and the fixed distance between the shower head and the heater platform allows the wafers fabricated from different chambers to be consistent in quality.
REFERENCES:
patent: 3632213 (1972-01-01), Trice
patent: 4728799 (1988-03-01), Gordon et al.
patent: 4987856 (1991-01-01), Hey et al.
Chung Ping-Chung
Lai Tso-Lung
Lu Tsung-Lin
Huang Jiawei
J. C. Patents
Meeks Timothy
United Microelectronics Corp.
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