Patent ID: 12258659

DETAILED DESCRIPTION OF THE INVENTION

The present invention is illustrated inFIGS.3-42.FIGS.3-5illustrate one embodiment of an evaporative source100of the present invention. A crucible130with six crucible pockets132is mounted inside of source housing112. A variety of crucible materials and construction techniques are known to those skilled in the art, including but not limited to: crucibles with high thermal conductivity, low melting point materials, such as copper or aluminum, that incorporate water cooling; crucibles constructed out of high melting point materials such as graphite, tungsten, or molybdenum; and crucibles with graphite liners or those that use surface oxidation to limit thermal conductivity from the evaporant to the crucible surface.

The intersection of pockets132on the crucible surface134defines pocket edges133around each pocket. Crucible130may have more or fewer pockets, the choice of six pockets being for illustrative purposes only. The crucible is mounted to the source such that it can rotate about the crucible axis of rotation235. An electron beam source (not shown) located inside the evaporative source100has an exit140, from which an electron beam142emanates. The beam is directed from the exit to the material heating location135by magnets, also located inside the source (also not shown). The deflection of electron beams for evaporative heating, as well as sweeping the beam for controllable heating is well known in the art. Using such a deflection system, the heating location135comprises a finite area that is generally within the heated pocket edge. A crucible lid or cover120includes a cover body122and a cover insert150. Cover120extends along a plane perpendicular to the axis to cover all but a selected at least one of the plurality of pockets132and is positioned over the pockets132and has a cover opening124formed by cover insert150. Rotation of crucible30allows for any one of the pockets to be open at a time. The uncovered pocket is aligned with heating location135and is thus termed the “heated pocket,” while all of the other pockets are termed “unheated pockets.” Location135is fixed relative to electron beam142, while each of crucible pockets132can be positioned near location135for sweepable heating of the exposed material. The area occupied by heating location135need not be larger than any one of pocket edges133to provide control of heating of the material in the pocket.

Each of crucible pockets132has a crucible surface portion134alocated on crucible surface134that is located between each pocket and all of the other pockets. Crucible surface portion134amay be co-planar with crucible surface134, may be a raised surface that is parallel to but above crucible surface134, or may be a recessed surface that is parallel to but below crucible surface134. The crucible surface portion134asurrounding each pocket may either be isolated (not connected) to other crucible surface portions134a, may be interconnected with the others and may be contained on crucible surface134or extend beyond the edge of crucible surface134. Crucible surface portions134ahas features that match that of a bottom surface160of cover insert150in the vicinity of the heated pocket, in matching pairs, that produces aligned, contacting surfaces. Bottom surface160of cover insert150and crucible surface portions134athus situated cooperate to form a contact barrier, thereby blocking the line-of-sight between the heated and all of the unheated pockets. In other words, there are matching pairs of cooperating surfaces on the cover insert and the crucible surface between each pocket.

A rotation mechanism (not shown) for rotating crucible130allows selection from among multiple pockets132, and a lifting mechanism250allows rotation without contact of cover120and crucible130. The rotation mechanism couples crucible130to source housing112through a copper coil housing113located between magnet pole plates114of source housing112(as shown inFIG.4), and can be controlled by external devices not shown to rotate crucible130about axis of rotation235. By controlling the rotational position of crucible130, any of pockets132can be brought into heating location135. The rotation mechanism can consist of AC or DC motors or rotary or linear pneumatic actuators, and may also include sensors mounted on crucible130and housing112to detect rotational position. The lifting mechanism250, including an actuator252and rods254that provide lifting motion to the cover120. Also shown is crucible130and electron beam source exit140. In one embodiment actuator252is a single action pneumatic actuator with a spring return enclosed in a bellows, with the spring forcing the cover into a normally up position. In another embodiment, actuator252is double acting, providing both raising and lower operations. Other lifting mechanism that could be used include, but are not limited to, lead screws, piezo-electric actuators, bimetallic elements, magnetic solenoid, and linear motors.

FIG.4shows a bottom view of the lifting mechanism250with a pair of rods254extending up through source housing112to contact cover120and a third rod254that is outside of source housing112and extends from actuator252directly to cover120. The motion involved in lifting the cover is shown more clearly in the side view ofFIG.5. The solid and dashed cover lifting components (actuator252, rods254and cover120) shows the extreme points of motion. Cover120is connected at its corners closest to the electron beam source through rods254to actuator252and at a furthest point from the electron beam source on cover120through a third rod254connected to actuator252. In the normally up, dashed position, bottom surface152of cover insert150clears the obstructing crucible, and in the forced down, solid position, the cover insert150is fully engaged with the crucible surface134or crucible surface portions134a. The combination of a rotational and lifting mechanism is generally useful for rotational crucibles providing a way of covering and uncovering multiple pockets.

FIG.6is a perspective view of cover120in an up position meaning that cover insert150is in a down or coupled position relative to cover body122. This position is attained when the lifting mechanism250raises cover120away from crucible130.FIG.7is a top plan view of cover120. In bothFIGS.6and7, there is illustrated the connecting locations127to which rods254are connected for lifting of cover120.

FIG.8is a bottom plan view of cover120ofFIG.7. Cover120has a bottom surface126and a plurality of bottom surfaces126athat interact with crucible surface portions134aof crucible130as well as copper coil housing113. Cover insert150also includes insert bottom surfaces154that interact with crucible surface portions134a.FIG.9is a side plan view ofFIG.6showing cover120with cover insert150.FIG.10is a front view of cover120shown inFIG.6.

FIG.11is a perspective view of cover120with cover insert150in a down position relative to cover body122. This position is attained when the lifting mechanism250lifts cover120to an up position away from crucible130to allow rotation of crucible130.FIG.12is a side, cross-sectional view of cover120in an up position relative to crucible130. As shown, neither cover body122nor cover insert150contacts any portion of crucible130. In this position, crucible130may be rotated to position one of the plurality of crucible pockets132to align with the cover opening124.FIG.13is a side, cross-sectional view of cover120lowered toward crucible130where cover insert150just begins to make contact with crucible surface134or crucible surface portion134aas the cover is being lowered by lifting mechanism250. InFIG.14, lifting mechanism continues to lower cover120until cover bottom surface126or bottom surface portions126acontact with crucible surface134or crucible surface portion134aand/or cover bottom surface126contacts copper coil housing113. As can be seen betweenFIGS.13and14, the movement of cover body122caused by cover body122being lowered to contact crucible surface134causes cover insert150to make contact with crucible surface134and stop its downward movement while cover body122continues its descent.FIGS.13and14show how cover insert150moves relative to cover body122such that cover insert122partially decouples from cover body122and seeks it own height and levelness when cover body122is lowered sufficiently.

Turning now toFIGS.15to18, there is illustrated various view of cover insert150showing structural features that isolate each pocket from and adjacent pocket by contact between the cover insert and the crucible including isolating the uncovered pocket from the covered pockets.FIG.15is a top perspective view showing insert body160having a V-shape with an inside edge163, an outside edge164. And a top surface162. In one embodiment top surface162is tapered in thickness from outside edge164to inside edge163such that outside edge164is thicker than inside edge163.FIG.16is a top view of cover insert150.FIG.17is a bottom perspective view of insert body160. Insert body160has an insert bottom surface168that is recessed back away from outside side edge164forming a ledge166. Bottom portion168extends along the V-shape over the entire length of insert body160. Insert bottom surface168further includes raised bottom portions154that extend along a portion of the arms of the V-shape to provide an insert bottom contact surface154athat is recessed a predefined distance from tapered edge163exposing a portion of non-contact surface of bottom portion168. Insert bottom contact surface154acontacts crucible surface134or crucible surface portions134awhen cover120is lowered sufficiently to contact crucible130.FIG.18is a bottom view of cover insert150.

FIG.19is a perspective view of cover body122. Cover body122has a top surface121, a cover opening123and a cover opening edge123a. Recessed from top surface121and along cover opening edge123ais a cover body ledge122athat coincides with ledge166of cover insert150. It should be noted that a cover opening122balso coincides with a cover insert opening160awhen cover insert150is assembled to cover body122. A pin161(not shown) may be fixedly attached to one of the cover opening122bor the cover insert opening160aso that cover insert150may partially decouple from cover body122to allow vertical movement of cover insert150relative to cover body122and vice versa. As discussed earlier and in the alternative, the cover insert can be partially secured to the cover body122by means of a spring like element or elements, which can provide additional downward force to the cover insert, thus increasing force against the crucible.FIG.20is a top view of cover body122.

FIG.21is a bottom view of cover body122showing structural features that are capable of mating contact with corresponding structural features of the crucible to further isolate each pocket from an adjacent pocket by contact between the covering surface and the crucible. This is similar toFIG.8but without the cover insert150. As inFIG.8,FIG.21shows cover body122with cover bottom surface126and bottom surface portions126athat are raised away from cover bottom surface126a predefined distance and serve the function to interact with crucible130as previously disclosed.FIG.22is a side cross-sectional view ofFIG.21.

Turning now toFIG.23, there is illustrated a second embodiment of the present invention showing cover120′. Cover120′ has a cover insert150′ in down position relative to cover body122′. This position is attained when the lifting mechanism250raises cover120′ away crucible130.FIG.24is a top plan view of cover120′. In bothFIGS.23and24, there is illustrated the connecting locations127′ to which rods254are connected for lifting of cover120′. In this embodiment, cover insert150′ is recessed within the V-shape opening of cover120′ such that the ends of cover insert150′ do not align with the front end of cover120′.

FIG.25is a bottom plan view of cover120′ ofFIG.23. Cover120′ has a bottom surface126′ and a plurality of bottom surfaces126a′ that interact with crucible surface portions134aof crucible130. Cover insert150′ also includes insert bottom surfaces154′ that interact with crucible surface portions134a.FIG.26is a side plan view ofFIG.23showing cover120′ with cover insert150′.FIG.27is a front view of cover120′ shown inFIG.23.

FIG.28is a perspective view of cover120′ with cover insert150′ in a down position relative to cover body122′. This position is attained when the lifting mechanism250lifts cover120′ away from crucible130to allow rotation of crucible130.FIG.29is a side view of cover120′ in an up position relative to crucible130. As shown, neither cover body122nor cover insert150contacts any portion of crucible130. In this position, crucible130may be rotated to position one of the plurality of crucible pockets132to align with the cover opening124′.FIG.30is a side view of cover120′ lowered toward crucible130where cover insert150′ just begins to make contact with crucible surface134or crucible surface portion134aas the cover is being lowered by lifting mechanism250. Lifting mechanism continues to lower cover120′ until cover bottom surface126′ or bottom surface portions126a′ contact with crucible surface134or crucible surface portion134a. As can be seen betweenFIGS.30and31, the movement of cover body122′ caused by cover body122′ being lowered to contact crucible surface134causes cover insert150′ to make contact with crucible surface134and stop its downward movement while cover body122′ continues its descent.FIGS.30and31show how cover insert150′ moves relative to cover body122′ such that cover insert122′ partially decouples from cover body122′ and seeks it own height and levelness when cover body122′ is lowered sufficiently.

Turning now toFIGS.32to35, there is illustrated various views of cover insert150′.FIG.32is a top perspective view showing cover insert150′ having a V-shape with a tapered top surface162′ with an outside side surface164′.FIG.33is a top view of cover insert150′.FIG.34is a bottom perspective view of insert body150′. Cover insert150′ has a bottom portion168′ that is recessed back away from outside side surface164′ forming a ledge166′. Bottom portion168′ extends along the V-shape over the entire length of cover insert150′. Bottom portion168′ further includes raised bottom portions154′ that extend along a portion of the arms of the V-shape to provide a bottom crucible contact surface154a′ that contacts crucible surface134or crucible surface portions134awhen cover120′ is lowered sufficiently to contact copper coil housing113.FIG.35is a bottom view of cover insert150′.

FIG.36is a perspective view of cover body122′. Cover body122′ has a top surface121′ and a cover opening123′. Recessed from top surface121′ and along cover opening123′ is a cover body ledge122a′ that coincides with ledge166′ of cover insert150′. It should be noted that a cover opening122b′ also coincides with a cover insert opening160a′ when cover insert150′ is assembled to cover body122′. A pin161(not shown) may be fixedly attached to one of the cover opening122b′ or the cover insert opening160a′ so that cover insert150′ may partially decouple from cover body122′ to allow vertical movement of cover insert150′ relative to cover body122′ and vice versa. As discussed earlier and in the alternative, the cover insert can be partially secured to the cover body122′ by means of a spring like element or elements, which can provide additional downward force to the cover insert, thus increasing force against the crucible.FIG.37is a top view of cover body122′.

FIG.38is a bottom view of cover body122′. This is similar toFIG.25but without the cover insert150′. As inFIG.25,FIG.38shows cover body122′ with cover bottom surface126′ and bottom surface portions126a′ that are raised away from cover bottom surface126′ a predefined distance and serve the function to interact with crucible130as previously disclosed.FIG.39is a side cross-sectional view ofFIG.38taken along line A-A.

Greater detail near the heated pocket of one embodiment is shown inFIG.40. Pocket edge133shown inFIG.40contains the heating position135, and thus pocket132shown inFIG.40is the heated pocket.FIG.40shows the source configured for coating, with cover120in the “up” position, in which cover body122and cover insert150are retracted from contact with crucible surface portion134a, permitting rotation of crucible130.FIG.41shows the cover “down” position. In the down position, cover insert150has bottom crucible contact surface154ain contact with crucible surface portion134a. The contact barrier thus formed extends along pocket132far enough to provide a contact barrier between the heated and unheated pockets. To reduce the need to service the cover by removing deposit material, the cover insert150can be replaced with a new cover insert150, which also can partially decouple from cover body122.

In this invention, the cover and crucible contact arrangement blocks contaminants from propagating from heated to unheated pockets by eliminating the line-of-sight movement of coating vapors. Due to the low pressure, vapors travel nearly unimpeded until they strike one of the surfaces within system100. Upon impact, a substantial amount of incident vapor molecules will stick to the surface, resulting in an accumulating deposit. By incorporating a partially decoupling cover insert150in cover120along with contact surfaces between cover body122and crucible surface134, deposits can accumulate over some period of time on the cover insert150without presenting a source for cross-contamination. Further, where the raised bottom portions154are set back from tapered edge163of cover insert150, the clearance between bottom portion168of tapered edge163and crucible130allows for deposits to accumulate on those surfaces without decreasing the ability of the raised bottom portions154to block contaminants, or to allow deposits to easily flake or rub off and contaminate other pockets. Also, some materials of interest, such as gold, weld when surfaces having deposits of those materials are brought into contact. Thus, surfaces having deposits of materials that contact weld can, under the conditions present in a high vacuum chamber, weld when brought into contact. Welding results in either binding mechanisms within the system or dislodging relatively large flakes of deposit if movement occurs. Welding is prevented in the present invention by preventing contact of surfaces of tapered edge163and bottom portion168and by providing regions for deposits that are away from possible contact points.

The manner in which cover body122contacts with the crucible in the first embodiment will now be explained. Crucible130has a plurality of pockets132, each of which has a crucible surface portion134aextending away from crucible130. Insert bottom contact surface154ais adapted to have approximately the same contour as crucible surface portion134a, as is best seen inFIG.42. When cover120is aligned with crucible130as inFIG.42, one of pockets132is uncovered, with tapered edge163closest to the uncovered pocket. As with the first embodiment, the edge of uncovered pocket corresponds to the heating location135, and thus the uncovered pocket is the heated pocket. Extending away from cover120towards crucible130are bottom surface portions126athat contact other crucible surface portions134a.

Operation of the Invention

When selecting between the multiple pockets, the relative motion between crucible and cover should proceed in a manner that does not allow for the crucible and cover to contact. From the described cooperation of the cover and crucible to form a contact barrier of the present invention, it would be obvious to one skilled in the art that crucible selection motion and cover motion must be controlled to provide the stated advantages. Thus, contact between the cover insert150,150′, or between any parts which have accumulated deposits should be minimized during pocket selection. Many mechanisms and control systems could be configured to achieve those advantages, and the descriptions and embodiments provided here are illustrative and are not meant to limit the scope of the present invention.

For the rotatable pocket configuration of the present invention, the cover and crucible form two halves of a contact barrier that would impede rotation of the crucible130. Both illustrated embodiments of the invention, thus, includes a rotation mechanism (not shown) for rotating crucible130to select from among multiple pockets132, and a lifting mechanism250to allow rotation without contact of cover120and crucible130. The rotation mechanisms couples crucible130to source housing112, and can be controlled by external devices not shown to rotate crucible130about axis of rotation235. By controlling the rotational position of crucible130, any of pockets132can be brought into heating location135. The rotation mechanism can consist of AC or DC motors or rotary or linear pneumatic actuators, and may also include sensors mounted on crucible and housing to detect rotational position.FIG.4shows a bottom perspective view of the lifting mechanism250, including an actuator252and rods254that provide lifting motion to the cover120(not shown). Also shown is crucible130and electron beam source exit140. In one embodiment actuator252is a single action pneumatic actuator with a spring return enclosed in a bellows, with the spring forcing the cover into a normally up position. In another embodiment, actuator252is double acting, providing both raising and lower operations. Other lifting mechanism that could be used with this invention include, but are not limited to, lead screws, piezo-electric actuators, bimetallic elements, magnetic solenoid, and linear motors.

The motion involved in lifting the cover is shown more clearly in the side view ofFIG.5. The solid and dashed cover lifting components (actuator252, rods254and cover120) shows the extreme points of motion. Cover120is connected at its corners through rods254to actuator252. In the normally up, dashed position, bottom surface152of cover insert150clears the obstructing crucible, and in the forced down, solid position, the cover120is fully engaged. The combination of a rotational and lifting mechanism is generally useful for rotational crucibles providing a way of covering and uncovering multiple pockets.

Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.