Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of coating supply or source outside of primary...
Reexamination Certificate
2002-01-11
2004-03-09
Padgett, Marianne (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of coating supply or source outside of primary...
C427S563000, C204S192380
Reexamination Certificate
active
06703081
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention builds on a method for vacuum treatment or on a method for producing powder.
According to the present invention a vacuum treatment installation is obtained, as well as used.
The present invention, in principle, has the objective of reactively depositing plasma-enhanced, i.e. through a PECVD method, materials on a deposition surface, be these materials which generally are extremely difficult to produce, namely metastable materials such as cBN, &agr;-Al
2
O
3
, C
3
N
4
or, in particular, diamond materials, or basically materials at maximally high deposition rates and at maximally low temperatures, in particular when Si-containing compounds, further particularly microcrystalline &mgr;C—Si:H, are to be deposited.
EP 0 724 026 by the same applicant as the present invention, corresponding to U.S. Pat. No. 5,753,045, discloses a method for the vacuum treatment of at least one workpiece, in which the workpiece is exposed in a vacuum atmosphere to a reactive gas excited by means of a plasma discharge. The workpiece surfaces to be coated are disposed offset with respect to the plasma beam axis such that thereon a plasma density obtains of maximally 20% of the maximum density obtaining in the plasma beam axis. This procedure permits deposition layers difficult of production, in particular those comprising metastable materials in particular of diamond, cBN, &agr;-Al
2
O
3
or C
3
N
4
. With respect to the definition of “metastable materials”, reference is made to “Lehrbuch der anorganischen Chemie”, Hohlemann-Wiberg, Walter Gruyer, Berlin, N.Y. 1976, Edition 81-90, p. 183 ff, which is to say materials which are deposited in a slightly reversible reaction.
According to the Swiss Patent Application 794/99 by the same applicant as the present invention, it has been recognized that said method—according to EP 0 724 026—surprisingly is also suitable for high-rate coating of surfaces, on the one hand, and for generating powder or cluster-form material on a collection surface, on the other hand.
Of disadvantage in these prior known processes is that therewith, on the one hand, only workpiece surfaces of relatively small, in particular planar, dimensions can be homogeneously treated, in particular coated, but that, on the other hand, it would be entirely desirable to increase the quantity of powder or clusters generated per unit time. Consequently, it would be desirable to realize, in particular for diamond coating, a relatively large-area, uniform layer thickness distribution also at maximally high coating rates.
SUMMARY OF THE INVENTION
The objective of the present invention is to attain such.
For this purpose the method according to the invention for the treatment of workpieces—also as a basis for the installation according to the invention is distinguished because, in the vacuum atmosphere, at least two plasma beams with substantially parallel beam axes are generated and the at least one workpiece surface to be treated is disposed along a surface in the vacuum atmosphere on which the plasma density distribution, predetermined by the plasma beams, is generated. The method for production according to the invention is, on the other hand, distinguished in that in the vacuum atmosphere at least two plasma beams are generated with substantially parallel beam axes and a collection surface for the powder is disposed in the vacuum atmosphere such that on it a plasma density distribution predetermined by the plasma beams is generated.
It was found that in the prior known approach, in particular due to its cylindrical symmetry with respect to the axis of the one plasma beam, complex dependencies result of the concentration of reactive species on the radial distance from the beam axis. If in particular the local concentration, of critical importance for the generation of diamond material, of atomic hydrogen in the prior known approach and as a function of the radial distance from the plasma beam axis is considered, a model calculation according to
FIG. 1
shows the concentration decrease with increasing radial distance, with the assumption of a linear distance dependence according to (a) and with the assumption of a quadratic distance dependence according to (b).
As explained, in
FIG. 1
the concentration function is depicted along a plane E which is at a distance X
min
parallel to the plasma beam axis A and viewed along a straight line G in plane E perpendicular to the beam axis A. The distance measure is normalized with X
min
, the concentration measure with respect to the maximum concentration on plane E at site S of distance X
min
.
Based on this representation, the reason is evident of why the prior known procedure with respect to deposition rate distribution presents problems, especially with relatively large workpiece areas to be coated if the one workpiece surface under consideration, or the several workpieces, is (are) each not disposed with their corresponding surface in such a way that they are rotationally symmetric about the beam axis A.
These problems are significantly reduced through the method proposed according to the invention.
Definitions
In the present specification the expression “workpiece support surface” is used if, according to the invention a workpiece treatment, in particular coating, is being addressed. The expression “collection surface” is used if powder or cluster generation is being addressed. The general term “deposition surface or “deposition configuration” is used if a “workpiece support surface” as well as also a “collection surface” jointly are being addressed.
In an especially preferred embodiment of the method according to the invention, onto the deposition surface a metastable material is deposited, preferably cBN, &agr;-Al
2
O
3
, C
3
N
4
or, especially preferred, diamond.
In a further preferred embodiment of the method according to the invention, a silicon compound is deposited onto the deposition surface preferably microcrystalline silicon &mgr;C—Si:H, and as a reactive gas silane is preferably employed.
In a preferred embodiment the plasma beams are realized as low-voltage arc discharges, highly preferred as high-current arc discharges, preferably by means of cold cathode discharges, but especially preferred by means of hot cathode discharges.
Further, the deposition surface is disposed in the vacuum atmosphere and with respect to the plasma beams such that along this surface predetermined minimum plasma density fluctuations occur. This is attained in particular thereby that along said deposition surface plasma densities of maximally 20% occur, preferably of maximally 10%, preferably even of maximally 5% of the plasma density maxima of the particular closest plasma beams, wherein further the plasma beams can be operated identically, i.e. in this case have substantially identical maximum plasma densities in their axes. But it is advantageous to optimize the plasma density distribution attained along deposition surfaces, for example of predetermined shape, through the specific tuning of the particular discharges, i.e. through the specific tuning of the beam-specific maximum plasma densities. For this purpose it is further proposed that the plasma beam discharges can be operated independently of one another, which opens the feasibility of carrying out said optimization specifically from case to case.
It was additionally and surprisingly found that with the proposed method a material deposition at very high deposition rates can be realized at temperatures at the deposition site of maximally 500° C. Accordingly, the methods according to the invention are preferably carried out such that by disposing the deposition surface such that the plasma density maxima obtaining on it are 20% of the closest beam plasma density maxima, a deposition rate on the deposition surface of minimally 400 nm/min is set up, preferably at said temperature of maximally 500° C.
In a further preferred embodiment, the plasma density distribution is tuned by means of at least one magnetic field parallel to the beam axis.
In a furt
Karner Johann
Pedrazzini Mauro
Notaro & Michalos P.C.
Padgett Marianne
Unaxis Balzers Aktiengesellschaft
LandOfFree
Installation and method for vacuum treatment or powder... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Installation and method for vacuum treatment or powder..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Installation and method for vacuum treatment or powder... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3230825