Patent Description:
Process shutter arrangements comprising a shutter disc, also known as dummy disc as it replaces a wafer which is usually processed on the chuck, and a shutter arm to rotate the disc from a niche of the processing chamber or a separate compartment towards a pedestal or chuck, which carries the wafer or other substrates during processing, are widely used in vacuum equipment for semiconductor and optical industries, for instance for conditioning or pasting processes to extend the replacement cycle of the process shields, or simply to cover the top of a chuck to protect it against dust or mechanical exposure during servicing. As such equipment is expensive and highly automized, service intervals should be minimized, and precision and reliability of any step be optimized. Due to shorter process times and respective high number of process cycles, a higher number of conditioning and/or pasting operations per time unit follows.

A dummy or shutter disc is a disc to replace a wafer in a processing position during a servicing, a conditioning, or a pasting step to protect the underlying equipment, especially the highly sensitive wafer bearing surface of the chuck. The disc should be able to receive a considerable amount of deposition material from the targets in case of target sputtering in the process chamber or allow a considerable amount of material to be removed when etching is performed during a so called conditioning or pasting step. When different sputter or conditioning/ pasting steps shall be performed, usually different discs will be used for sputtering or conditioning/pasting steps.

A shutter sickle is the part of a shutter arm which carries the shutter disc and is provided at least with the positioning tenons. The sickle can essentially have the form of a sickle, however, can be also disc or paddle like itself and having slots to let the pins of the chuck pass during rotational movement to and from a center position over the chuck. Therefore, the inner periphery of the sickle DSi can define an actual periphery of the sickle or the innermost position of at least one of the tenons, which preferably sit in a position having essentially the same distance from the center of the sickle.

In <CIT> a shutter disk having notched areas is disclosed to be used with a shutter arm assembly for fully automated handling. However additional installations like a modified cover-ring have to be provided and connected with the shielding to avoid mutual movement, which makes the installation laborious and might influence the placing precision due to thermal expansion of the shields.

To center the position of the shutter disk it is further known to apply a sensor on a shaft coupled to a robotic driven arm to detect the respective rotational position. To improve the respective sensing system, the same applicant as above discloses in <CIT> a sputter disc which is centered by a central blind hole cooperating with an alignment post on a rotating blade. Therewith a relatively robust construction is necessary for the disc and the blade. At the same time the use of up to three different sensors is proposed to detect the disc in the housing.

Other prior art process shutter arrangements are known from <CIT> and <CIT>.

Therefore, there is a need for light and dimensionally minimized components which can be moved faster and enable a high placing precision of the shutter disc, without the use of sophisticated multi-sensor systems.

Surprisingly, it has been found that a respective process precision and high repeatability as well as minimized dimensions the components can be achieved by mere mechanical provisions of an inventive process shutter arrangement for a vacuum process system.

It is therefore an objective of the present invention to provide a process shutter arrangement comprising:.

The bearing surface may extend radially from the inner periphery DSi of the sickle, e.g. in an outward direction and/or in a center direction. The tenons being positioned near or adjacent to the inner diameter DSi.

The disc may further comprise a circumferential rim extending in a horizontally sidewise direction and/or in a vertically downward direction.

The mortises can be arranged within an inner diameter DRi of the rim or within a projection of the inner positioning rim, and adjacent, e.g., immediately adjacent, to the rim or the projection. Mortises may have a basic rectangular geometry.

Depending on the type of process to be performed when the disc protects the chuck, the material or the coating respectively plating of the disc can be chosen. If only a coating or plating of the disc is provided, at least the second side of the disc should be coated or plated and, if not protected by a clamp or holder on the chuck during the pasting or conditioning step, the second side of the rim, and the periphery of the disc respectively rim. For conditioning or servicing stainless steel or for a lightweight construction titanium or a ceramic material will work, whereby ceramic can be any densely sintered ceramic, e.g., aluminum oxide, silicon nitride or silicon carbide. If, however a pasting process should be performed, a respective pasting material like titanium or aluminum can be used as well as more exotic pasting materials like ZrFe or Pt.

An inventive shutter arm may comprise a sidewall to enhance the stiffness of the sickle when space is limited. The sidewall may form at least in part an outer periphery DSo of the sickle, whereat the outer diameter DDo of the disc fits into the inner periphery DWi of the sidewall. The chuck dimension relates directly to the size of a wafer to be treated in a vacuum process which can be PVD, a CVD or an etch process as an example. With reference to the disc to chuck relation to be treated at the chuck, as an example for a disc having a flat first side as shown in <FIG> below, a very small or even no oversize will suffice. The same may apply for a disc with a rim having a vertical extension over the first surface as shown in <FIG>. However, to avoid any contact to the wafer bearing surface when sitting on the top of the chuck, a few millimeters may be added for the rim in a radially outwards direction of the the wafer bearing surface, whereas a few tenth of a millimeter for the vertical extension suffice to avoid touching of an all flat wafer bearing surface of a chuck by the disc.

The sidewall of the sickle may encompass the bearing surface in an angular range of about180° or smaller and can be a continuous or a interrupted sidewall, e.g. a sequence of pins. The bearing surface of the sickle may extend over an angular range of <NUM>° - <NUM>° and will be usually of <NUM> ± <NUM>° of the inner diameter DSi.

Tenons may have a basic rectangular, a circular or an oval geometry and have to be symmetrically with reference to a middle plane extending along an axes η<NUM>-<NUM> and the height direction z of a tenon. When Tenons have a rectangular or square base, round corners or a circular end geometry will be usually provided.

The disc may further comprise a flat and/or a notch at or in its outer diameter DDo, and the sickle may comprise a corresponding flat side and/or a nib, e.g., at the inner diameter DWi of the side wall. Such features may be provided when the chuck to be protected has respective positioning nibs or flat sides for the wafer to be processed.

The shutter arm can be made of a material having an elastic modulus of at least <NUM> to <NUM> GPa to provide a high stiffness and avoid disturbing vibrations. Thereby densely sintered ceramic materials like aluminum oxide, silicon nitride, or silicon carbide are preferred due to their light weight.

In an alternative embodiment the position of tenons and mortises can be reversed, which means that tenons can be provided at the first surface of the disc and mortises can be provided at the bearing surface of the sickle.

It is a further objective of the present invention to provide a shutter disc having an essentially circumferential outer diameter DDo, a thickness t, a first surface, and a second surface, the disc comprising at least three positioning mortises in the first surface near the outer diameter DDo, each mortise being centered and symmetric with respect to a plane between a radially axis ξ<NUM>-<NUM> in an xy-plane of the disc and the respective vertical, and having two long sides a positioned in parallel or right angled to axis ξ<NUM>-<NUM>. The mortises having further a short dimension b, and a depth dimension d, where b < a. It should be mentioned that neither positions of the mortises need to be regularly, nor need dimensions a<NUM>-<NUM>. b<NUM>-<NUM>, d<NUM>-<NUM>, be the same for a, b or d. However, some regularly positions, e.g., <NUM>°, <NUM>°, <NUM>°, and/or identical dimensions a, b, d for mortises as well as identical dimensions for the respective dimensions m, n, h for the tenons can ease manufacture and/or handling of the disc respectively sickle.

It is a further objective of the present invention to provide a shutter arm comprising a shaft with mounting means, a bearing sickle with an inner periphery DSi, and at least three positioning tenons near or adjacent to the inner diameter DSi, being in operative connection with positioning mortises to position the disc when set on the positioning tenons or on an optional bearing surface of the sickle. Thereby the disc may sit directly on the bearing surface or on top of the tenons, depending on the height of the tenons and respective depth of the mortises and the provision of a bearing surface.

The bearing surface may extend radially from the inner periphery DSi of the sickle, e.g., in an outward direction and/or in a center direction. The tenons being positioned near or adjacent to the inner diameter DSi. The shutter arm further comprising a shaft with mounting means for the bearing sickle with a bearing surface radially extending from an inner periphery DSi of the sickle, and optionally a semi-circumferential side wall encompassing the bearing surface. Each tenant having an axis η<NUM>-<NUM> positioned radially in an xy-plane of the sickle, and a long dimension m, a short dimension n, and a height dimension h, when n ≤ m. When n = m the tenon may have a circular or a square basis. Tenons are centered with reference to a plane comprising radially oriented axis η<NUM>-<NUM> and a respective vertical.

When the disc is mounted on the bearing surface of the sickle or on top of the tenons, tenons rest in respective mortises. Therefore, angular orientation and radial position of mortises and tenons has to be the same. As mentioned above mortises and tenons may be interchanged from the disc to the arm respectively vice-versa.

Due to positioning means which may be provided on the chuck to position wafers having a notch or a flat respective positioning means like a flat and a flat side, a notch and a nib, can be foreseen with the disc which replaces the wafer for the servicing, conditioning or pasting step, and the sickle to bear the respective disk. As an example, flats and/or notches may be provided at or in the outer diameter DDo of the disc, whereat the flat side and/or the nib may be provided at the inner periphery DWi of the sidewall.

It is a further objective of the present invention to provide a vacuum process system comprising a vacuum process chamber which houses a chuck with pins being movably mounted in a z-direction to a pin drive and a process shutter arrangement as discussed above and will be further discussed at the hand of the figures below. Thereby the arm of the process shutter arrangement is mounted to a vacuum side of a rod having a vertical rotational axis R, the rod being mounted to the chamber by a feedthrough, and being in operative connection with a shutter drive at the atmosphere side of the rod, to rotate the arm in a horizontal plane from a niche of the processing chamber or a separate compartment in a central position over the chuck, to enable that the pins of the chuck take over the disc.

The pin drive of the chuck may be mounted to the process chamber, on atmosphere side or on the vacuum side. To lift the disc after the sickle has been rotated in a central position over the chuck, the drive may extend the pins in a uniform joint movement in an upper end position which can be between <NUM> and <NUM>, e.g. <NUM> to <NUM> above the horizontal top of the chuck. Therefore, pins have to be provided within the inner diameter DSi of the sickle, when the latter is in the central position.

The process system may further comprise a control unit connected to the pin drive and the shutter drive to coordinate rotational movement of the arm and linear z-movement of the pins to rotate the arm with the disc and lift and lower the disc when the arm is in the central position.

The chuck of the process system can be a static chuck or a dynamic chuck which can be moved in a vertical direction from a loading position into a processing position and vice-versa.

For a static chuck at least a handling cut-out in the process shields with a drivingly movable screen-shutter can be provided, when only a niche for the rest or idle position of the sickle is foreseen. Additionally, a disc handling opening can be provided with a respective lock in the chamber wall when a separate compartment should be foreseen. Disc handling cut-out and disc handling opening being mutually aligned and tailored to allow handling of a plate shaped disc. This can be in analogy to the substrate handling arrangement as disclosed in <CIT> of the same applicant. Special reference is made to <FIG> and respective description.

Similar provisions can be made for a dynamic chuck as shown in <FIG> and respective description of <CIT>. Opening and closing of the handling cut-out in the process shields in this case can be performed by at least two telescopic cylindric shields encompassing the outer diameter of the chuck, whereat one of the shields is mounted to and moves with the chuck, whereby respective cut-outs are opened or closed by the respective other shield.

It is a further objective of the present invention to provide a method to use an inventive process shutter arrangement in a chamber of an inventive vacuum processing system as discussed above, whereat the method comprises the following steps:.

The Method may further comprise the following steps:.

The invention shall now be further exemplified with the help of figures. Figures show the invention only in an exemplary way to outline the important features of the invention. The dimensions and geometrical relations of the different features as shown may differ from actual embodiments of the invention.

The components and relevant functional principles of a process system operating in a conditioning or pasting mode are shown at the hand of <FIG>. The exemplary process system <NUM> as shown has a vacuum pump <NUM> attached to the vacuum chamber <NUM> which houses a chuck <NUM> to process wafers or other flat substrates and an inventive process shutter arrangement consisting of a shutter disc <NUM> and a shutter arm <NUM>. The shutter arm is mounted to the rod <NUM> of a shutter drive <NUM> to rotate the shutter disc from a niche <NUM> of the processing chamber <NUM> or a separate compartment <NUM> in a central position over the chuck. As usual the rod runs through a vacuum feedthrough <NUM>. When positioned over the chuck <NUM>, pins <NUM> lift the shutter disc <NUM> in z-direction according to the double arrows from the bearing surface <NUM> of the sickle <NUM>. This is the very position which is shown in <FIG> with pins <NUM> in fully extended position. It should be noted that the pins need not be necessarily lifted above the sidewall as schematically shown. A lift of one or some few millimeters may suffice, as long as the sidewall does not encompass more than <NUM>° of the bearing surface, which allows a rotation of the sickle into and out of central position without touching the lifted disc with its sidewall. The pins <NUM> can be the pins as used to lift a wafer from a wafer blade. Thereafter the sickle <NUM> is rotated back into the niche <NUM> or separate chamber <NUM> and pins are retracted in the chuck surface to position the disc on the chuck to protect its surface during a following conditioning, pasting process or servicing operation. The present shutter disc and shutter arm can be designed extremely flat, so that only a short lift is necessary to enable the back-rotation of the arm with the disc unloaded from the sickle <NUM>. The control unit <NUM> can be used to trigger and control respective rotational movement of the arm <NUM> and vertical movement of the pins <NUM>, which can be initiated by an operator for service or by the system control (not shown) to which the control unit <NUM> may be integrated. The pin drive <NUM> which can be positioned on the atmosphere or the vacuum side of the process chamber <NUM>, which also houses the pin transmission and further components (not shown) used for the operation of the chuck.

To load the disc <NUM> again on the sickle <NUM>, the process is reversed, pins <NUM> are extended to lift the shutter disc <NUM> from the chuck <NUM> and the sickle <NUM> is rotated in a central position so that the bearing surface <NUM> is positioned between the chuck <NUM> and the lifted disc <NUM>. For long term process stability with series of some hundred process / pasting / conditioning cycles or more it is very important that positioning of the sickle and picking up of the disc from the chuck is performed with utmost precision. Therefore, light weight but highly rigid materials having a high modulus of elasticity, e.g., at least <NUM> to <NUM> GPa, should be used for the arm and sickle to avoid any disturbing material deformation due to change of temperature or load. In the present case aluminum oxide was used as material for the shutter arm with the sickle, however other materials of similar properties, e.g., as shown above may be used too. The shutter drive motor <NUM> is coupled to the rod <NUM> and an encoder to ensure high position accuracy.

However most importantly the picking up of the disc by the sickle of the arm is supported by respective positioning features on the disc and sickle. So, when the disc is lowered by retraction of the pins towards the sickle and pins <NUM> are further retracted in a position at least below the bearing surface <NUM>, precision positioning is completed by three positioning tenons <NUM> in the sickle surface <NUM> which enter into the respective mortises <NUM> in the lower disc surface <NUM>, whereby the position of the disc <NUM> is perfectly defined on the bearing surface <NUM> of the sickle <NUM> before it is rotated back in rest position. Therewith for the next conditioning or pasting operation the shutter drive can rotate the arm with the disc in position above the chuck and handover the disc to the pins at the very right place without further measures.

It should be mentioned that especially the shown thickness dimensions of arm and sickle, and disk, as well as dimensions of the precision positioning features are oversized in the figures to better show the functionality.

It is further evident that vacuum process systems as shown in <FIG> usually will have additional features like gas inlets for PVD or CVD processes, sputtering targets to deposit materials, etching devices or the like to process a wafer or other flat substrates, which only makes conditioning, pasting or service cycles necessary. However, as the present invention focuses on the improvement of a process sputter arrangement, only respective relevant installations are discussed and shown in the figures.

A shutter disc <NUM> with three positioning mortises <NUM> in a first surface <NUM> and a rim <NUM> optionally provided with a flat <NUM> and/or a notch <NUM> is shown in <FIG>. The shutter disc having a thickness t, the mortises having a length a, a width b, and a depth d (see also <FIG>) and being positioned with their longitudinal axes ξ<NUM>-<NUM> radially in a peripheral position at <NUM>°, <NUM>° and <NUM>° of the disc perimeter. The disc also comprises three nicks <NUM> in a second surface <NUM> of the disc <NUM>, positioned on an inner extension of the projection of axes ξ<NUM>-<NUM>, adjacent to mortises <NUM>. These nicks can be used for a first placing step, e.g. during a first manual placing of the disc. Similarly nicks and/or bevels can be used with any other embodiment of a shutter disc. Mortises can have a circumferential bevel <NUM>' and tenons can have a circumferential chamfer <NUM>', each alone or in cooperation with each other to ease matching of the two positioning elements. Mortises <NUM> can be positioned on axis ξ<NUM>-<NUM> in parallel and symmetric to it as indicated in solid lines, or alternatively right angled to axis ξ<NUM>-<NUM> as indicated in dashed lines and reference number <NUM>", which will usually be also symmetric as referred to before.

In <FIG> a similar shutter disc <NUM> with three positioning mortises <NUM> in the first surface <NUM> and a rim <NUM> here provided with a flat <NUM> is shown. In the case of the disk in <FIG> the rim <NUM> also has a vertical extension which slightly towers over the first surface <NUM> and thereby may encompass the wafer bearing surface of the chuck <NUM> and sit on a peripheral chuck surface.

Despite of the fact, that the disks as shown in <FIG> and <FIG> can be designed very flat with a thickness t from <NUM> to <NUM>, or <NUM> to <NUM>, the provision of a rim <NUM> of lower thickness tR, which should refer to the thickness of a wafer to be processed, can make it easy to clamp the disc on the chuck with usual wafer clamps, e.g. during sputtering processes. As far as provided, the rim <NUM> can be small but at the same time wide enough to provide place for the positioning flat <NUM> or notch <NUM>. As an example, disc dimensions for a <NUM> chuck, which are usual chuck dimensions to process <NUM> wafers, can be: <MAT>.

A shutter disk arm <NUM> which can be mounted to the rod <NUM> of a rotation unit by a shaft <NUM> with flange and positioning slots <NUM> to level the sickle is shown in <FIG>. Alternatively, or in addition a central mounting on the shaft, as shown in <FIG>, can be foreseen.

The arm <NUM> further comprises a sickle <NUM> with a bearing surface <NUM> and sidewall <NUM>. Three positioning tenants <NUM>, each offset by <NUM>° from the next tenant, are placed on the bearing surface <NUM> next to the inner diameter of the sickle, with their axes η<NUM>-<NUM> arranged radially towards the inner periphery of the sickle DSi. Therewith, when the disc <NUM> is positioned on the sickle <NUM> axes ξ<NUM>-<NUM> of mortises <NUM> and axes η<NUM>-<NUM> of the tenants <NUM> coincide and the inner periphery DWi of the sidewall <NUM> encompasses the outer diameter DDo of the disc <NUM> on the bearing surface <NUM>. To ensure highest positioning precision the small dimension b of the mortise <NUM> and the respective dimension n of the tenant <NUM> should be very similarly sized so that, as an example in the case of an arrangement for a <NUM> wafer, the difference should be about b - n = <NUM> ± <NUM>. In contrast to that the long dimension a of the mortise <NUM> should be provided considerably longer than the respective dimension m of the tenant <NUM> to enable thermal compensation. As an example, again for a <NUM> wafer arrangement, when using a metal disc and a ceramic sickle, the difference should be at least <NUM> to <NUM>, depending on the maximal thermal load during processing. When nibs or flat sides are used to position the wafer on the chuck, a flat side <NUM>' and/or a nib <NUM>' can be foreseen as shown in dashed lines. Reference number <NUM> refers to an optional out-cut to allow an optical sensor (not shown), to acknowledge correct positioning of the disc. The optical sensor can be mounted in a niche or a separate rest chamber for the arm and disc or can be integrated on the arm <NUM>. One or more openings <NUM> as shown in dotted lines may be provided in the bearing surface <NUM> and a lower part of the side wall <NUM> to allow protrusions from the chuck or pins positioned further outward on the chuck to pass. Width w of the bearing surface should be from at least about <NUM> the length m of a tenon till about <NUM> to allow pins <NUM> to pass inside when lifting the disc <NUM>.

The magnifying glass in the upper part of the drawing shows on the left side a view from the center of the sickle <NUM> towards a tenant <NUM> on the bearing surface <NUM> and a sideview in a <NUM>° perspective to the left side.

Tenants may have a maximal length dimension m, a maximal width dimension n, and a height h whereby: <MAT> <MAT> <MAT>.

Therewith mortises having a maximal length dimension a and a maximal width dimension b, can be used with the following dimensions: <MAT> <MAT> <MAT>.

<FIG> shows further details of a positioning tenant <NUM> in top view. The tenant <NUM> comprising two circular edge sections of radius r, a straight middle part here of length l, and an upper finish with a circumferential chamfer <NUM>'. As an example, r can be <NUM> and height h of the tenant can be also <NUM>. Thereby minimized dimensions and good positioning properties can be achieved. A variation of the length l of the straight middle part can be from about <NUM> to 4r or more, which may depend of the width w = (DWi - DSi) / <NUM> of the bearing surface <NUM>. Alternatively, round tenants, tenants with an oval base or other convenient base forms as known to the man skilled in the art can be used.

A further embodiment of an inventive shutter arm is shown in <FIG>. Contrary to the forgoing arm embodiment in this case circular tenons <NUM>, mounted on an inner end of cantilevers <NUM>, are used to position and hold the respective disc, which means the disc sits on the tenons only. The cantilevers project radially from the side wall <NUM> towards the center of the sickle <NUM>. To hold the disc save in balance, the tenons are placed in a <NUM>° position from each other at a mere virtual inner periphery of the sickle DSi, so that there is no further need of the bearing surface <NUM> as shown in <FIG> or <FIG>. Axes η<NUM>-<NUM> cut each other in the center point of the sickle. Such a shutter arm can be combined with any of the previous disc embodiments when the mortises are arranged in a respective <NUM>° position.

Claim 1:
A process shutter arrangement for a vacuum process system comprising:
- a shutter disc (<NUM>) having an essentially circumferential outer diameter DDo, a thickness t, a first surface (<NUM>), and a second surface (<NUM>), the disc comprising at least three positioning mortises (<NUM>) in the first surface (<NUM>) near the outer diameter DDo, each mortise being centered with respect to a radially axis ξ<NUM>-<NUM> in an xy-plane of the disc and having two long sides a positioned in parallel or right angled to the respective axis ξ<NUM>-<NUM>;
- a shutter arm (<NUM>) comprising a bearing sickle (<NUM>) with an inner periphery DSi, and at least three positioning tenons near or adjacent to the inner diameter DSi, and corresponding with positioning mortises (<NUM>) to position the disc when set on the positioning tenons or on an optional bearing surface of the sickle.