Coating processes – Direct application of electrical – magnetic – wave – or... – Chemical vapor deposition
Patent
1996-09-20
1998-01-06
Pianalto, Bernard
Coating processes
Direct application of electrical, magnetic, wave, or...
Chemical vapor deposition
118 58, 118722, 4272556, 4272557, 427261, 427265, 427402, 4274071, 4274301, 427596, C23C 800
Patent
active
057052352
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a procedure and a device for the production of three-dimensional structures through optically stimulated precipitation of a structure material from a fluidic (gaseous or liquid) compound.
Using a process known as LCVD (Laser-Assisted Chemical Vapor Deposition) a laser beam focused on an even substrate surface serves to locally warm the substrate in the focus area. The substrate in this case is located in, for example, a reactive vapor atmosphere. In the warmed zone a chemical reaction is triggered in which the molecules of a gaseous compound on the substrate surface are thermally decompounded. In this way a certain portion of these molecules is deposited on the substrate surface (a metal, for example, when a metallo-organic gaseous compound is used) and only in the extremely limited area heated by the laser beam. If the substrate and the laser beam focal point in the substrate level are now moved in relation to each other, the warmed zone also moves on the substrate surface. In this way tracks/strips can be `written` (deposited) with the precipitated material (the structure material).
It is also known that LCVD can be used to produce self-supporting, three-dimensional rod and spiral shaped structures from silicon, boron, or carbon, or to deposit a spiral of tungsten on a silicon rod. (Leyendecker et al., Appl. Phys. Lett. 39 (11), Dec. 1, 1981, 921-923: Bauerle et al., Appl. Phys. A, 147-149 (1983); Boman et al., Micro Electro Mechanical Systems 92. Travemunde (Germany). Feb. 4-7, 1992, pg. 162-167. In these procedures a laser beam of sufficient lumination is focused on a substrate surface. After a certain amount of structure material has been precipitated onto the substrate surface, the focal point and the substrate surface are moved away from each other with a speed that maximally equals the rate of growth of the structure material in the direction of the relative movement. A thin rod of structure material then grows on the substrate.
The basis for the emergence of the rod (14) is as follows: In essentially opaque materials like carbon (graphite) for example, practically the entire optical beam is absorbed on the surface of the already precipitated material. The precipitated material is therefore particularly hot on the surface on which the laser beam is turned. The temperature of the interior of the precipitated materials drops exponentially in relation to the heat conducting characteristics of the material. The thermal decompounding of the compound which produces the structure material therefore takes place first on the upper surface of the precipitated structure material on which the laser beam has been focused and by which it is heated. Growth takes place from that point up to the laser beam. This effect is further strenghened by the fact that the newly precipitated material absorbs the laser light so that the hottest place shifts in the direction of the laser beam.
The task underlying the present invention is to specify an optical LCVD process and a device for the performance of such a process with which structures extending into three-dimensions can be generated particularly from materials which are minimally absorbent and essentially opaque, and, in addition, to allow better control of growth and direction of reproduction.
This task is accomplished through the process according to the invention and using the device according to the invention.
The process and device according to the invention are particularly suited for the manufacture of three-dimensional structures from minimally absorbent materials. The direction in which the material is precipitated and in which the structure grows can be easily controlled.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following the invention is further clarified using the drawings as reference:
FIG. 1: A schematic representation for clarification of how the present invention may be executed; and
FIG. 2: A simplified representation of a device for performance of the process according to the invention.
In the present process, use wil
REFERENCES:
Chemical Abstracts, vol. 122, Columbus, Ohio, US; Abstract No. 92666, Lehn, O. et al., "Three-dimensional laser direct writing of electrically conducting and isolating microstructures." Materials Letters 21 (1994) 131-136 (No month avail.).
Journal of Applied Physics 72(1992) 15 Dec., No. 12, New York, US, "Microfabrication of three-dimensional boron structures by laser chemical processing," Johansson et al.
Patent Abstracts of Japan, vol. 8, No. 84 (E-239) (1521) 18 Apr. 1984 & JP,A,59 005 621 (Nippon Denki) 12 Jan. 1984.
Lehmann Olaf
Stuke Michael
Kinsella N. Stephan
Max-Planck-Gesellschaft zur Forderung der Wissenschaften e.v.
Murray William H.
Pianalto Bernard
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