Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2002-09-26
2004-04-20
Versteeg, Steven (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192120, C204S192130, C204S192150
Reexamination Certificate
active
06723210
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for improving a performance of a sputtering target, and more particularly to a method for improving a performance of a sputtering target in a magnetron sputtering system.
BACKGROUND OF THE INVENTION
During the semiconductor or TFT-LCD (Thin Film Transistor Liquid Crystal Display) manufacturing processes, a sputtering technology generally is used in a thin film deposition. According to the momentum transfer theory, the sputtering technology utilizes the ion of a plasma to be deposited on the deposition element with gas phase, so as to proceed with a thin film deposition.
Presently, the sputter for TFT-LCD is always a magnetron sputtering system. Please refer to
FIG. 1
which shows a schematic view of the equipment of the general magnetron sputtering system. In the magnetron sputtering system, a magnet
10
is disposed behind a sputtering target
11
and actuated by a stepper motor. And a substrate
12
is deposited on a plane
13
. The magnet
10
is a full-length rectangular form and scans repetitively and retracingly between the two sides of the sputtering target
11
. When the magnet
10
approaches the retracing points near the two sides of the sputtering target
11
, because of the mechanical efficiency of the stepper motor, the scanning velocity of the magnet
10
can not help but be reduced, even suspended. Thus, the magnetic field at the two sides of the sputtering target will be greater than that at the center thereof, so that the target erosion rate at the two sides of the sputtering target will also be specifically greater than that at the center thereof. This situation causes the restriction of the performance of the expensive sputtering target.
Please refer to FIG.
2
and Table 1.
FIG. 2
illustrates an erosion depth measurement of a MoW (tungsten molybdate) alloy target which has been sputtered by a conventional sputter. And Table 1 illustrates a contract table of the same. Among these, the depth of the MoW alloy target
20
is 16 mm. As shown in FIG.
2
and Table 1, the ranges
21
,
24
, and
27
of the left retracing area
210
and the ranges
23
,
26
, and
29
of the right retracing area
211
of the MoW alloy target
20
have thicker erosion depth (erosion rate) than the ranges
22
,
25
, and
28
at the center thereof. Thus, the performance of the MoW alloy target
20
is only 34%.
TABLE 1
Erosion
Erosion
Erosion
thickness
thickness
thickness
Position
(mm)
Position
(mm)
Position
(mm)
21
13.34
22
9.00
23
14.87
24
10.46
25
4.39
26
10.46
27
14.47
28
8.64
29
12.99
Please refer to FIG.
3
and Table 2.
FIG. 3
illustrates an erosion depth measurement of the Al (aluminum) target which has been sputtered by a conventional sputter. And Table 2 shows a contract table of the same. Among these, the depth of the Al target
30
is 16 mm. As shown in FIG.
3
and Table 2, the ranges 308, 307, 315, 322, 329, 337, 338, 309, 316, 323, 330, and 339 of the downside retracing area
32
and the ranges 302, 301, 310, 317, 324, 331, 332, 303, 311, 318, 325, and 333 of the upside retracing area
31
of the sputtered Al target
30
have thinner residue thickness than the other ranges 304, 312, 319, 326, 334, 305, 313, 320, 327, 335, 306, 314, 321, 328, and 336. Thus, the performance of the Al target
30
is only 33%.
TABLE 2
Position
301
302
303
304
305
306
307
308
Residue
6.2
3.9
1.9
8.7
8.4
8.5
1.4
3.6
thickness (mm)
Position
309
310
311
312
313
314
315
316
Residue
6.4
5.6
4.6
10.9
11.1
10.8
5.1
6.0
thickness (mm)
Position
307
318
319
320
321
322
323
324
Residue
6.2
4.7
11.2
11.8
11.2
4.8
6.0
6.0
thickness (mm)
Position
325
326
327
328
329
330
331
332
Residue
5.2
11.0
11.3
11.1
4.5
6.1
6.4
3.6
thickness (mm)
Position
333
334
335
336
337
338
339
Residue
1.6
8.5
8.7
8.4
2.1
3.9
6.7
thickness (mm)
Because of the defects described above, the applicant keeps on carving unflaggingly to develop “method for improving performance of sputtering target” through wholehearted experience and research.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for improving the performance of a magnetron sputtering system.
It is another object of the present invention to provide a stepwise power controlling method for complying with the scanning position of the magnet in the magnetron sputtering system.
According to an aspect of the present invention, a method for improving a performance of a sputtering target in a magnetron sputtering system having a magnet repetitively, and retracingly scanning between two sides thereof and receiving a power input changing with a scanning position of the magnet includes steps of stepwise reducing the power input while the magnet approaches a specific distance range near a retracing point, so as to reduce an erosion rate of the sputtering target by the magnetron sputtering system, and increasing the power input to a specific value while the magnet leaves the specific distance range, wherein the power input changes with the scanning position of the magnet, so as to improve the performance of the sputtering target.
Preferably, the method is a power changing method.
Preferably, the magnet is controlled by a stepping motor.
Preferably, the power input is supplied by a DC power supply.
Certainly, the power input can be changed by means of revising a computer program of the DC power supply.
Certainly, the power input can be changed by means of revising software of said magnetron sputtering system.
Preferably, the specific distance range has a direct proportion to a scan range of the magnet in magnitude.
Preferably, the sputtering target is made of one selected from a group consisting of an alloy, an oxide, and a metal.
Certainly, the alloy can be one of a tungsten molybdate (MoW) and a neodymium aluminate (AlNd).
Certainly, the oxide can be one of indium tin oxide (ITO) and indium zinc oxide (IZO).
Certainly, the metal can be one of chromium (Cr) and aluminum (Al).
Preferably, the power input is changed stepwise.
In accordance with another aspect of the present invention, a method for improving a performance of a sputtering target in a magnetron sputtering system having a magnet repetitively and retracingly scanning between two sides thereof and receiving a power input changing with a scanning position of the magnet includes steps of defining a scanning center at a substantially half position of a scanning range of the magnet, reducing the power input gradually while the magnet is moved from the scanning center to a retracing point, so as to reduce an erosion rate of the sputtering target by the magnetron sputtering system, and raising the power input gradually while the magnet is moved from the retracing point to the scanning center, wherein the power input changes with the scanning position of the magnet, so as to improve the performance of the sputtering target.
Preferably, the method is a power changing method.
Preferably, the magnet is controlled by a stepping motor.
Preferably, the power input is supplied by a DC power supply.
Certainly, the power input can be changed by means of revising a computer program of the DC power supply.
Certainly, the power input can be changed by means of revising software of said magnetron sputtering system.
Preferably, the scanning range of the magnet has a direct proportion to a distance from the retracing point in magnitude.
Preferably, the sputter target is made of one selected from a group consisting of an alloy, an oxide, and a metal.
Certainly, the alloy can be one of a tungsten molybdate (MoW) and a neodymium aluminate (AlNd).
Certainly, the oxide can be one of indium tin oxide (ITO) and indium zinc oxide (IZO).
Certainly, the metal can be one of chromium (Cr) and aluminum (Al).
Preferably, the power input is changed stepwise.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings, in which:
REFERENCES:
patent: 6413382 (2002-07-01), Wang et al.
patent: 6425988 (2002-07-01), Mont
Chen Yung-Fu
Teng Tun-Ho
Hannstar Display Corp.
Versteeg Steven
Volpe and Koenig P.C.
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