Abrading – Precision device or process - or with condition responsive... – Computer controlled
Reexamination Certificate
1999-02-19
2001-05-15
Rachuba, M. (Department: 3724)
Abrading
Precision device or process - or with condition responsive...
Computer controlled
C451S009000, C451S287000, C451S443000, C451S041000, C451S056000
Reexamination Certificate
active
06231425
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polishing apparatus and method, more especially to polishing apparatus and method for polishing substrates, in particular a semiconductive substrate among them.
BACKGROUND ART
FIGS.
14
(A) and
14
(B) show a conventional polishing apparatus for polishing a wafer (substrate). Referring to FIGS.
12
(A) and
12
(B), according to the conventional polishing apparatus, a wafer
2
is polished through the steps of dropping a droplet of a slurry, which contains an abrasive agent and which is fed from a slurry feed means
6
, on a polishing pad
1
adhered to a rotatable polishing table
3
, pressing the wafer
2
rotated by a spindle
7
against the polishing pad. In order to remove debris and the like which clog traps (grooves) formed on the surface of the polishing pad
1
, conditioning of a polishing pad (called as “Ex-SITU conditioning”) is performed by using a diamond disc
5
installed on a conditioning drive means
4
in the interval of one and next polishing steps (runs).
Conventionally, conditioning conditions have been determined by practicing a pilot operation before advancing an actual polishing step of polishing a wafer which is to be changed into a product. Explaining in more detail, according to the prior art method, a conditioning condition is set as follows. Many pilots (blank wafers) are polished changing the conditioning time. The thickness of each pilot is measured after a given time of polishing. When the pilot thickness coincides with the set thickness, the corresponding conditioning time is taken as a conditioning condition. In case of polishing wafers belonging to the same lot group or the same patterned group, the above pilot procedure by using one blank wafer per several ten pieces of lots is taken, and the conditioning time is determined on the result of this procedure.
SUMMARY OF THE DISCLOSURE
However, the following problems are involved in the aforementioned prior art.
First problem is a change of a polishing speed (polishing and removing rate) with lapse of time, which offers a fear of polishing a wafer excessively.
This is because a polishing condition varies depending on disorder such as the change of a polishing pad in its surface state, variation between lots, ununiformity of an abrasive agent and the like.
Second problem is complication of calculation for determining a conditioning condition (or formulation of a recipe).
This is because the determination of a conditioning condition is required for every part different in properties by correspondingly performing a pilot operation according to the conventional method of setting the conditioning condition, since the degree of lowering a polishing efficiency due to the fatigue of a polishing pad, clogging and the like changes depending on the kind of polishing object (kind of film and the like) and device pattern formed on a wafer.
Accordingly, an object of the present invention is to provide a polishing apparatus and method capable of stably polishing a substrate regardless of the difference in polishing objects, change of a polishing means with lapse of time and the like.
A polishing apparatus of the present invention includes a polishing device polishing a substrate, a conditioning device conditioning the polishing device during polishing the substrate and a conditioning control system which controls the conditioning device based on a friction force exerted between the polishing device and the substrate during polishing the substrate.
In a polishing method of the present invention, the friction force exerted between the polishing device and the substrate is detected during polishing the substrate, and the polishing device is conditioned during polishing the substrate based on the detected friction force.
According to the present invention, information for setting the conditioning condition of the polishing device can be obtained during polishing the substrate so that it is needless to practice a pilot operation for obtaining a conditioning condition in the interval of runs. Further, a partial information corresponding to a partial property can be obtained during polishing the substrate in case that properties of a substrate (for example, device patterns or kinds of film) are partially different from each other. Accordingly, it is easy to set optimum conditioning conditions which are partially different from each other based on the partial information.
Moreover, an information for setting the conditioning condition of the polishing device can be obtained during polishing the substrate to become a product. This information is then fed back to the conditioning control system. Accordingly, an appropriate conditioning condition can be set instantly against disorder such as variation between lots, difference of patterns each formed on substrates and change of the polishing device with lapse of time and the like to stabilize sufficiently polishing speed (removal rate) and total polishing amount only by controlling the time.
REFERENCES:
patent: 5609511 (1997-03-01), Moriyama et al.
patent: 5639388 (1997-06-01), Kimura et al.
patent: 5876265 (1999-03-01), Kojima
patent: 5904609 (1999-05-01), Fukuroda et al.
patent: 5975997 (1999-11-01), Minami
patent: 6093080 (2000-07-01), Inaba et al.
patent: 10-15807 (1998-01-01), None
patent: 10-315124 (1998-12-01), None
S. Inaba et al., “Study of CMP Polishing Pad Control Method”, 1998 Proceedings Third International Chemical-Mechanical Planarization for ULSI Multilevel Interconnection Conference (CMP-MIC), Feb. 19, 1998, pp. 44-51.
Inaba Shoichi
Katsuyama Takao
Tanaka Morimitsu
NEC Corporation
Rachuba M.
Young & Thompson
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