DE102011006833A1 - substrate carrier - Google Patents

Abstract

The invention relates to a substrate carrier for transporting and holding substrates during coating in plasma chambers. The substrate carrier consists of a material that is dimensionally stable up to 800 ° C and has longitudinal struts and transverse struts that surround a plurality of openings, inserted into the substrates and supported along the edges of the longitudinal underside on the edges in such a way that plasma wrap is reduced is. The lower and / or upper sides of one or more of the transverse struts have a shape that supports a gas and plasma flow transversely to the transport direction of the substrate.

Description

The invention relates to the design of the transverse struts of substrate carriers, which enables a particularly good suitability for the conduction of plasma and gas over the wafer surface by means of a corresponding shaping. The terms substrate carrier and wafer carrier or substrate and wafer are used synonymously below.

Substrate supports are used in particular in semiconductor and solar cell production. They serve to hold wafers or substrates during the transport and processing operations of the wafers. The processing operations are in particular coating and etching processes, to which the wafers are frequently subjected at high temperatures and pressures, deviating from the atmospheric pressure. Since the substrate carriers also hold the substrates during processing, they are also exposed to the processing conditions.

The machining operations are directed either to one or both sides of the flat wafer. It is thus necessary to design the holder of the wafers in the substrate carriers in such a way that they cover the smallest possible area of the surfaces. In addition, the processing processes of a wafer side should affect the second wafer side as little as possible. This is particularly problematic in plasma processes since the plasma tends to flow around the edges of the wafers and also partly coat the backside. This phenomenon is called "grasping" and is undesirable in the majority of cases.

Another goal is to let the machining processes act as evenly as possible on the entire surface of the wafer and on all wafers in the substrate carrier.

The substrate carriers considered here have a planar, grid-like construction, wherein the wafers are held in the grid openings. The grid openings are preferably rectangular, but they may also be diamond-shaped, round, oval or rectangular or square with bevelled or rounded corners. The shape of the grid openings corresponds in shape and dimensions of the wafer to be transported. The wafers are held in the grid openings by peripheral edge, small hooks, pins or similar constructions on which they rest.

A corresponding construction is, for example, in the DE 20 2009 001 817 U1 described where the lattice-like construction for stability improvement has a widened coverage as an outer frame. This wafer carrier consists of a material that is stable up to 800 ° C., that is preferably metallic (aluminum, steel, tungsten, titanium) or consists of ceramic or carbon fiber reinforced carbon (CFC). The plasma flow on the surface should be carried out undisturbed by the fact that a surface of the substrate carrier which is as flat as possible is formed.

In the US 2005/0061665 A1 describes a wafer carrier which also provides space for a plurality of wafers. The wafer carrier has a base frame and one or two subframes. The mounting of the wafers takes place in the openings of the base frame by means of clips which are arranged on the subframe and press the wafers against the base frame. The wafer carrier should preferably be suitable for galvanic processes. The base frame is preferably made of non-conductive material, while the sub-frames and the clips are used to make a conductive connection to the wafers, so that a galvanic process is possible. However, this type of frame is not suitable for plasma enhanced processes because the uneven conductive surfaces would greatly inhomogenize the plasma distribution.

In prior art plasma processing systems for wafers, the substrate carriers with the wafers are often driven through the processing equipment at a constant speed while the plasma treatment is taking place. The plasma is introduced from above and / or from below to the wafer and sucked off excess plasma or gas laterally to the transport direction. So there is a complicated flow of plasma over a moving surface.

The object of the present invention is to positively influence the plasma flow over the surface of the loaded substrate carrier.

According to the invention the object is achieved by the design of the substrate carrier according to claim 1. Advantageous embodiments are shown in the dependent claims.

The substrate carrier according to the invention for transport and for holding substrates during the coating in plasma chambers consists of a material which is dimensionally stable up to 800 ° C. and has longitudinal struts and transverse struts. These surround a lattice-like a plurality of openings in which the substrates are inserted and held along the edges of the longitudinal and transverse struts. In particular, the substrates are supported on their underside at the edges in a manner that minimizes plasma grab. The lower and / or the upper sides of the transverse struts of the substrate carrier have a shape that supports a gas and plasma flow transversely to the transport direction of the substrate. The longitudinal and transverse struts to the Edges of the substrate carrier are wider than the longitudinal and transverse struts, which are not at the edge of the substrate carrier.

As transverse struts, the struts of the substrate carrier are referred to, which are aligned substantially perpendicular (transverse) to the transport direction of the substrate carrier. The longitudinal struts are then the struts, which are aligned substantially parallel to the transport direction.

It has been shown that the flow of plasma and gas above and below the substrates can be influenced by the design of the transverse struts. According to the invention, therefore, the cross struts are designed differently from the longitudinal struts. Thus, the transverse struts have at least one groove and / or / at least one bulge which run parallel to the longest extent of the transverse struts and thereby preferably in the middle thereof or symmetrically to the latter. The grooves or bulges extend over the entire or at least a large part, preferably 75% of the length of the transverse struts, particularly preferably at least 50% of the length of the transverse struts. The grooves and / or bulges may be interrupted in their course.

A preferred embodiment has at least one groove on the top and bottom of the transverse struts. A further preferred embodiment has at least one groove on the upper side of the transverse struts and at least one bulge on the underside. Grooves and bulges are reversed in a further preferred embodiment between the top and bottom. A further preferred embodiment has at least one bulge both on the upper and on the underside of the transverse struts.

The transverse struts of one and the same substrate carrier can advantageously be configured differently, so that, for example, some of the transverse struts have grooves on the upper side and bulges on the underside, while others have cambers on both sides. Corresponding variations are preferred.

As a result of the design according to the invention of the transverse struts, the gas and plasma flow over the surface of the substrates is advantageously influenced. It is achieved a more uniform processing of the surfaces. The gas and plasma flow is advantageously directed by the transverse struts in such a way that it more easily reaches the suction devices located laterally, transversely to the transport direction.

The substrate carrier according to the invention preferably consists of a material which is dimensionally stable up to at least 800 ° C. Particularly suitable are steel, aluminum, tungsten, titanium ceramic or carbon fiber reinforced carbon (CFC). If the substrate carrier is composed of several individual parts, the individual parts can each consist of different materials.

In a preferred embodiment, the substrate carrier consists of CFC. It is produced in a lamination process in which different layers of prepregs are placed on top of each other and then carbonized by heat. Advantageously, the stacked prepregs are already designed so that the intended shape of the crossbars is achieved. This may preferably be done by placing one or more cores between the layers of prepregs. The core material used is preferably molded CFC or graphite. However, the core material need not be identical to the material of the prepregs. It is essential that the core of a dimensionally stable up to 800 ° C material, preferably from up to 800 ° C dimensionally stable carbon fibers. A further preferred production method provides that the prepregs are inserted into a mold, which in turn has a bulge, so that the prepregs have a groove after carbonization. A further preferred embodiment provides molded substrate carriers molded from a piece of CFC. Other methods of making the substrate supports are known in the art.

In a preferred embodiment, a core forms a plurality of bulges. Thus, for example, a curvature at the top and bottom of a transverse strut can be formed by a core having a circular or oval cross-section in the interior of the transverse strut.

The substrates are held in the substrate carrier in a manner known per se. Preferably, the substrate is held on peripheral edges on the longitudinal and transverse struts. This advantageously also reduces the plasma volume. However, there remains an area at the edge of the substrate that is not exposed to machining. A further preferred embodiment of the holder therefore provides for arranging hooks on the longitudinal and transverse struts which support the substrates approximately at a punctiform point on their underside. This reduces the unworked area at the bottom. Another solution uses pins in the longitudinal and transverse struts to support the substrate. The longitudinal and transverse struts should continue to be designed so that edges with acute or right angles are avoided. Advantageously, the longitudinal and transverse struts are chamfered so that the edges are inclined to the substrate surface without having a level jump.

In order to minimize the plasma attack, due to the automation (loading and Discharge of the substrate substrate) required circumferential gap between longitudinal and transverse beams and the substrate advantageously designed as narrow as possible.

characters

1 shows the schematic diagram of a substrate carrier according to the invention ( 1 ). The openings ( 2 ) for receiving the wafers are of longitudinal ( 3 ) and cross struts ( 4 ) surround. In the openings ( 2 ), the wafers of pens ( 21 ). The longitudinal ( 31 ) and cross struts ( 41 ) at the edge of the substrate carrier ( 1 ) are wider than those ( 3 . 4 ) located inside the surface of the substrate carrier ( 1 ) lie. Shown are two continuous vaults ( 42 ) on cross struts ( 4 ) and a vault ( 42a ) in the middle of the substrate carrier ( 1 ) has an interruption. The transport direction (B) indicates how the substrate carrier passes through the treatment areas.

2 shows a substrate carrier according to the invention, which in the transverse struts ( 4 ) Grooves ( 43 ), which extends over the entire length of the transverse struts ( 4 ). The cross-section of the grooves has a rounded cavity.

3 to 8th show various embodiments of transverse struts ( 4 ). 3 shows a cross strut ( 4 ), which has a curvature ( 42 ) having. The vaulting ( 42 ) is passed through the core ( 44 ) formed in the interior of the transverse strut ( 4 ) and here has a semicircular cross-section. The cross brace ( 4 ) has two edges ( 22 ), which are used to hold the wafers ( 5 ) serve. The edges ( 22 ) also continue on the longitudinal struts (not shown), so that a circumferential supporting edge ( 22 ) arises. The edges ( 22 ) are in the direction of the wafers ( 5 ) bevelled so that no acute angles arise that could adversely affect the plasma flow. The execution after 4 has two parallel bulges ( 42 ) separated by two separate cores ( 44 ) be formed. 5 shows an embodiment in which a, in cross-section rounded groove ( 43a ) of two cores ( 44 ) is flanked. The cores ( 5 ) have circular cross sections here. The embodiment according to 6 has a bulge on the top ( 42 ), while on the bottom two parallel, triangular in cross-section, grooves ( 43b ). 7 shows a cross strut ( 4 ) with a bulge ( 42 ) on the bottom. The bulge at the bottom is characterized by a curved toward the bottom core ( 44 ) educated. The embodiment according to 8th shows a cross strut ( 4 ) each with a curvature ( 42 ) on the top and the bottom of the transverse strut ( 4 ). The vaults are here by two cores ( 44 ) educated.

LIST OF REFERENCE NUMBERS

1

Wafer carrier (substrate carrier)

2

Openings for receiving the wafers (substrates)

21

Pins for supporting the wafer

22

circumferential edge to support the wafer

3

longitudinal struts

31

Longitudinal struts on the edge of the substrate carrier

4

crossbars

41

Cross struts on the edge of the substrate carrier

42

Vaulting on the cross struts without interruption

42a

Camber on the cross braces with interruption

43

Grooves in the cross braces

43a

Grooves in the cross braces with rounded cross-section

43b

Grooves in the transverse struts with triangular cross-section

44

core

5

wafer

B

Transport direction of the substrate carrier

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202009001817 U1 [0006]
• US 2005/0061665 A1 [0007]

Claims (10)

Substrate carrier for transport and for holding substrates when coated in plasma chambers, wherein the substrate carrier consists of a dimensionally stable up to 800 ° C material and has longitudinal struts and cross struts which surround a plurality of openings, inserted into the substrates and along the edges of the longitudinal and transverse struts are held, characterized in that the substrates are supported on the underside at the edges so that a Plasmaumgriff is reduced and the lower and / or upper sides of one or more of the cross struts have a shape that a gas and plasma flow supported transversely to the transport direction of the substrate. Substrate carrier according to claim 1, characterized in that the longitudinal and the transverse struts, which are arranged directly on the edge of the substrate carrier and run parallel to this, are wider than the longitudinal and the transverse struts, which are arranged between other longitudinal and transverse struts. Substrate carrier according to claim 1 or 1, characterized in that transverse struts, which are not arranged directly on the edge of the substrate carrier, have at least one along its longest extent extending groove on the top and / or the bottom. Substrate carrier according to claim 1 or 1, characterized in that cross struts, which are not arranged directly on the edge of the substrate carrier, have at least one along its longest dimension extending bulge on the top and / or the bottom. Substrate carrier according to claims 3 and 4, characterized in that at least some of the transverse struts, which are not arranged directly on the edge of the substrate carrier, on the upper side of the transverse struts bulges and on the underside of the transverse struts grooves or conversely on the upper side of the transverse struts grooves and on the underside of the transverse struts have bulges that run along the longest extent of the transverse struts. Substrate carrier according to claim 4 or 5, characterized in that in the bulge a core is laminated. Substrate support according to claim 6, characterized in that the core consists of a material stable to 800 ° C material, preferably made of carbon fibers. Substrate support according to claim 7, characterized in that the up to 800 ° C dimensionally stable material of the core is molded. Substrate carrier according to one of the preceding claims, characterized in that the substrates are supported on the underside at all edges circumferentially and the plasma chamber handle reducing. Substrate carrier according to one of the preceding claims, characterized in that the substrates are supported on the underside by means of pins and / or hooks, and the Plasmaumgriff is reduced by minimizing the distance between the substrate and the longitudinal or transverse struts.

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