Scanned focus deposition system

Details Scanned focus deposition system Scanned focus deposition system

1999-06-07

2002-12-24

Mills, Gregory (Department: 1763)

Coating apparatus

With vacuum or fluid pressure chamber

With means to apply electrical and/or radiant energy to work...

C118S620000, C156S272800, C156S272400, C219S121660, C219S121680, C219S121690, C219S121730

Reexamination Certificate

active

06497193

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject scanned focus deposition system is generally directed to a system for uniformly depositing an evaporant material onto a substrate. More specifically, the scanned focus deposition system is directed to a laser deposition system wherein the uniform deposition of evaporant material from a target onto a substrate is facilitated by optimally controlling the target material's consumption.
Generally in laser deposition techniques, an evaporant material source is excited by a coherent energy beam such that particles of the evaporant material are released from the source and deposited onto a proximally disposed substrate surface. In these deposition techniques, the evaporant source—or target—may be placed, along with a substrate, within a vacuum chamber. A pulsed laser beam generated by a source located outside the vacuum chamber is then directed by optical components into the vacuum chamber. The optical components include, among other things, a focusing element which focuses the laser beam to impinge upon the target, defining an impingement spot. The concentrated energy at the impingement spot causes the generation of a highly directed evaporant plume that emanates from the target toward the proximally located substrate. The particles of target material contained in the evaporant plume then deposit onto the substrate's surface. By sustaining this deposition process while the substrate is rotated or otherwise displaced in controlled manner, a coating of target material may be formed on the substrate.
In many applications of this technique, the uniformity of deposition is of paramount concern. Numerous factors bear on the uniformity that may ultimately be realized. Perhaps chief among them is the degree to which the release of the target's evaporant material is regulated. The target includes a given mass of evaporant material which ‘wears’ as the deposition process progresses. The progressive wear of evaporant material potentially yields ruts and divots formed in the surface of the target. Consequently, the regularity (concentration, direction of release, . . . ) with which particles of the evaporant material are released from the target is quickly disrupted unless adequate aversive measures are taken. There is, therefore, a need for a deposition system wherein such aversive measures are adequately taken to optimize the uniformity of deposition that the system may realize.
2. Prior Art
Deposition systems, including pulsed laser deposition systems, incorporating one or more aversive measures to minimize the detrimental effects of target wear are known in the art. The best prior art known to Applicant includes U.S. Pat. Nos. 5,654,975; 5,724,173; 5,606,449; 5,661,290; 5,374,817; 5,144,120; 4,568,142; 4,504,110; 4,327,959; 4,218,112; 3,642,343; and, 3,508,814.
One aversive measure incorporated in deposition systems known in the art is to rotate the target about a rotation axis normal thereto. Another is to simultaneously scan the laser beam impinging upon the target along, for instance, the target's radial extent. A system employing these measures is disclosed in U.S. Pat. No. 5,654,975 entitled “SCANNING LASER BEAM DELIVERY SYSTEM,” and assigned to the Assignee of the present invention. In that system, a laser beam source and a beam transfer assembly cooperatively generate and direct an optical path having a terminal segment that impinges upon a target evaporant. An automatically controlled scanning mechanism displaces the beam transfer assembly in appropriate manner to translate the terminal segment of the optical beam path in a direction substantially normal to the longitudinal direction along which it extends.
While this system yields marked improvement over prior art deposition systems in the uniformity of deposition realized on a substrate, a number of shortcomings yet prevail. First, the strict lateral translation of the optical beam path terminal segment does not necessarily preserve the normal distance between the given focusing element and the target surface. In typical deposition systems, the planar front face of the target is not squarely oriented towards the incoming energy beam; for, the incident angle formed by the incoming beam relative to the target's front face must be something other than 90° if the resulting evaporant plume is to be directed towards the given substrate and not directly back towards the incoming energy beam, itself. Consequently, as the incoming beam is translated in a direction normal to its propagating direction, the focusing element is displaced either toward or away from that portion of the target's front facial plane on which it is to direct the energy beam. The beam's focus on the target is thus disturbed. That is, the effective shape and size of the impingement spot which the incoming energy beam forms on the target at a given instant in time is not preserved.
Another shortcoming prevails in the fact that the beam transfer assembly comprising all the optical components for forming at least the terminal segment of the energy beam is displaced in its entirety to effect the lateral translation of the beam path terminal segment. The practical inefficiencies inherent in such cumbersome manipulation of components are readily apparent.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to effect substantially uniform deposition of evaporant material contained in a target onto a substrate.
It is another object of the present invention to realize substantially uniform deposition of the target evaporant material onto a substrate using a pulsed laser deposition technique.
It is another object of the present invention to optimally regulate the consumption of the target evaporant material.
It is another object of the present invention to scan at least that portion of a coherent energy beam impinging upon the target in a manner that optimally preserves the beam's focus on the target.
It is yet another object of the present invention to effect the necessary scanning of a coherent energy beam in a simple and efficient manner.
It is still another object of the present invention to scan a coherent energy beam along the target by translating a focusing element along a scanning path that substantially preserves the beam's focus on the target.
These and other objects are attained in the present invention which provides a deposition system for substantially uniform deposition of an evaporant material onto a substrate. The deposition system comprises: a source for generating a coherent energy beam; a substantially planar target containing the evaporant material which is disposed in spaced relation to the substrate; a focusing element optically coupled to the source for focusing the coherent energy beam onto the target; and, an actuator coupled to the focusing element for reversibly translating that focusing element along a scanning path directed substantially parallel to a target plane defined by the target. The focused coherent energy beam defines an impingement spot on the target. The impingement spot is displaced responsive to the translation of the focusing element along the scanning path. The focus of the coherent energy beam on the target thus remains substantially preserved.
While enhanced uniformity of deposition may be realized in accordance with the present invention even without target rotation, the target is rotated in a preferred embodiment about a target rotation axis substantially normal to the target plane. Also in that embodiment, the actuator is adapted to translate the focusing element in reciprocal manner in accordance with a predetermined rate profile. The rate profile is defined based upon the position of the impingement spot relative to the target rotation axis. Preferably, the rate profile is defined by a substantially sinusoidal displacement profile, the rate of focusing element translation being inversely related to the displacement of the impingement spot from the target rotation axis.
In an alternate embo

Affiliated with

Also associated with

Rating

Scanned focus deposition system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Scanned focus deposition system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scanned focus deposition system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2974834