Shutter disk having a tuned coefficient of thermal expansion

A shutter disk having a tuned coefficient of thermal expansion is provided herein. In some embodiments, a shutter disk having a tuned coefficient of thermal expansion may include a body formed from a first material comprising at least two components, wherein a ratio of each of the at least two components to one another is selected to provide a coefficient of thermal expansion of the body that is substantially similar to a coefficient of thermal expansion of a second material to be deposited atop the body.

BACKGROUND

Embodiments of the present invention generally relate to the field of semiconductor process chambers, and more particularly, to shutter disks for use in semiconductor process chambers.

2. Description of the Related Art

Conventional semiconductor device formation is commonly performed in one or more process chambers, typically combined to form a multi-chamber processing system (e.g., a cluster tool) which has the capability to process multiple substrates (e.g., semiconductor wafers) in a controlled processing environment. To maintain process uniformity and ensure optimal performance of the process chamber, various conditioning operations are periodically performed. For example, in a physical vapor deposition (PVD) processing chamber, one commonly used conditioning operation is a “burn-in” process, wherein a target disposed in the PVD processing chamber is bombarded with plasma ions to remove oxides or other contaminants from the target prior to performing substrate processes. Another commonly used conditioning operation is a “pasting” process, wherein a covering is applied over material deposited on process chamber surfaces to prevent the material from flaking off the process chamber surfaces and contaminating the substrate during subsequent processes.

In both of the aforementioned conditioning operations, a shutter disk may be positioned via a transfer robot atop a substrate support disposed in the process chamber to prevent the deposition of any materials upon the substrate support. The shutter disk typically comprises a material having a mechanical stiffness sufficient enough to resist deformation due to the additional weight of the deposited material. For example, the shutter disk commonly comprises a metal alloy, such as stainless steel (SST), or a ceramic, such as silicon carbide (SiC).

However, shutter disks constructed of such materials weigh a substantial amount, leading to increased costs due to providing and maintaining a transfer robot capable of securely maneuvering the shutter disk. In addition, the coefficient of thermal expansion (CTE) is limited in range, resulting in a potentially significant difference between the coefficients of thermal expansion of the shutter disk and deposited materials, leading to diminished adhesion between the deposited material and the surface of the shutter disk, thus increasing the risk of the deposited material spalling or flaking off and contaminating the underlying substrate support. To alleviate this problem, the surface of the shutter disk may be textured via an abrasive blasting process to increase adhesion. However, due to the hardness of materials such as SST or SiC, such processes are difficult and costly.

SUMMARY

A shutter disk having a tuned coefficient of thermal expansion is provided herein. In some embodiments, a shutter disk having a tuned coefficient of thermal expansion may include a body formed from a first material comprising at least two components, wherein a ratio of each of the at least two components to one another is selected to provide a coefficient of thermal expansion of the body that is substantially similar to a coefficient of thermal expansion of a second material to be deposited atop the body.

In some embodiments, a process chamber may include a chamber body defining an inner volume having a target comprising materials to be deposited atop a substrate disposed therein; a substrate support disposed within the chamber body for supporting the substrate; a shutter disk for protecting the substrate support, the shutter disk comprising a body formed from a composite material having at least two components, wherein a ratio of each of the at least two components to one another is selected to provide a coefficient of thermal expansion of the body that is substantially similar to a coefficient of thermal expansion of materials to be deposited on the shutter disk; and a transfer robot movably coupled to the chamber body for transferring the shutter disk to the substrate support.

In some embodiments, a shutter disk having a tuned coefficient of thermal expansion may include a body having a top surface, bottom surface and a peripheral surface coupling the top surface to the bottom surface, wherein the body comprises aluminum and silicon provided in a ratio of aluminum to silicon of about 1:4 to about 7:3 and wherein the body has a coefficient of thermal expansion that is substantially similar to a coefficient of thermal expansion of a material to be deposited atop the body.

DETAILED DESCRIPTION

Embodiments of the present invention generally relate to semiconductor manufacturing processing chambers, and more particularly, to shutter disks. The inventive apparatus includes a shutter disk for use in conditioning operations of process chambers. The inventive apparatus may advantageously provide a light weight, cost effective shutter disk that is resistant to deformation and provides a tuned coefficient of thermal expansion and improved adhesive properties.

FIG. 1is a top view of an exemplary shutter disk in accordance with some embodiments of the present invention.FIG. 1Adepicts a cross sectional view from the center line of the exemplary shutter disk ofFIG. 1, in accordance with some embodiments of the present invention. To best understand the invention, the reader should refer simultaneously toFIGS. 1 and 1A. Although described herein as a disk, the shutter disk may have any suitable geometry as required to operate within a particular processing chamber.

The shutter disk100generally comprises a body102having a top surface104and bottom surface106and an outer diameter108. Although discussed in terms of an outer diameter and referred to as a disk, the shutter disk100is not limited to round shapes and may have any shape suitable for use in a process chamber as disclosed herein. The bottom surface106may comprise features107to interface with the components of a transfer robot (not shown) to facilitate stable and precise movement.

The top surface104is generally planar and has an orientation substantially perpendicular to the centerline109of the body102. The bottom surface106is also generally planar and has an orientation substantially perpendicular to the centerline109of the body102. In some embodiments, the body102has an outer diameter108of about 6 to about 12 inches, for example about 6, 8, or 11.85 inches, and a thickness between the top surface104and bottom surface106of about 0.1 to about 0.25 inches, for example, about 0.15 inches.

In some embodiments, a double step110may be formed in the outer portion of the bottom surface106, as shown inFIG. 1A. The double step110comprises an inner step112and an outer step114. The inner step112and outer step114are substantially parallel to the bottom surface106. An inner wall116separates the inner step112from the bottom surface106. The outer step114extends further into the body102than the inner step112as referenced from the bottom surface106. The outer step114is separated from the inner step112by an outer wall118. The outer wall118and the inner wall116are substantially parallel to the centerline109of the body102. In some embodiments, the transition between the outer step114and the top surface104may be rounded. A groove120may be formed in the bottom surface106of the body102radially inward of the inner step112. In some embodiments, the groove120includes an inner groove wall122, an outer groove wall124and a groove bottom126. The inner groove wall122and outer groove wall124are substantially parallel to the centerline109of the body102. The groove bottom126is substantially perpendicular to the centerline109of the body102. In some embodiments, the groove bottom126extends further into the body102than the outer step114as referenced from the bottom surface106.

The body102may be constructed of any suitable material having a mechanical stiffness sufficient enough to resist deformation due to the additional weight of materials which may be deposited atop the shutter disk100. In some embodiments, the material may also be lightweight so as to allow the shutter disk100to be easily maneuvered by a transfer robot. In some embodiments, the body102may be constructed from a metal composite, such as aluminum silicon (AlSi). The body102may be fabricated via any method suitable for forming the desired shape, for example, mold casting, die casting, spray casting, spray deposition, or the like.

In some embodiments, the body102may comprise a first material having a coefficient of thermal expansion (CTE) substantially similar to a second material being deposited atop the shutter disk100to facilitate adequate adhesion between surface128of the shutter disk100and the material being deposited, thereby preventing the deposited material from flaking (e.g., falling off) and reducing particle generation. For example, in embodiments such where titanium (Ti) or titanium nitride (TiN) is to be deposited atop the shutter disk100(e.g., having a CTE of between about 9-11 ppm/° C.), the body102may comprise AlSi, having a CTE of about 9-11 ppm/° C., or about 11 ppm/° C. In some embodiments, a ratio of components of the material used to form the body102may be varied to provide a tunable CTE range. For example, in embodiments such as where the body102comprises AlSi, the ratio of aluminum to silicon may be from about 1:4 to about 7:3, resulting in a CTE of about 5 to about 17 ppm/° C. For example, in embodiments where the ratio of aluminum to silicon is about 1:3.5 to 1:4.5, and most preferably 1:4, the CTE may be about 5 ppm/° C. In embodiments where the ratio of aluminum to silicon is about 3:6.5 to 3:7.5 and most preferably 3:7, the CTE may be about 7 ppm/° C. In embodiments where the ratio of aluminum to silicon is about 1:0.75 to 1:1.25 and most preferably 1:1, the CTE may be about 11 ppm/° C. In embodiments where the ratio of aluminum to silicon is about 7:2.5 to 7:3.5 and most preferably 7:3, the CTE may be about 17 ppm/° C.

In some embodiments, the surface128of the body102may be textured to facilitate improve adhesion with a material deposited thereon, thereby preventing the deposited materials from falling off the shutter disk100. The surface128of the body102may be textured by any process suitable to adequately texture or roughen the surface128of the body102, for example, an abrasive blasting process, such as grit blasting, sand blasting, bead blasting, or the like. In some embodiments, such as where the body102comprises AlSi, the surface128of the body102may be textured to a roughness average of up to between about 600 to about 800 Ra, by a suitable process, for example, via a grit blasting process.

In some embodiments, a method of forming a shutter disk having a tuned CTE is also provided. For example, in some embodiments, the body102may be formed from a first material comprising at least two components, wherein a ratio of each of the at least two components with respect to one another is selected to provide a coefficient of thermal expansion of the body102that is substantially similar to a coefficient of thermal expansion of a second material to be deposited atop the body. In some embodiments the components of the first material may be aluminum and silicon. The ratio of aluminum to silicon may be selected to provide a desired coefficient of thermal expansion as discussed above (e.g., the ratio of aluminum to silicon may be from about 1:4 to about 7:3, resulting in a CTE of about 5 to about 17 ppm/° C.). The CTE of the second material may be determined and the ratio of the components of the first material may be selected to provide a CTE that substantially matches the CTE of the second material. For example, in some embodiments, titanium (Ti) or titanium nitride (TiN) is to be deposited atop the shutter disk100. The CTE of titanium (Ti) or titanium nitride (TiN) is between about 9-11 ppm/° C. As such, the body102may comprise aluminum and silicon, having a controlled ratio of aluminum to silicon to provide a CTE of between about 9-11 ppm/° C., or about 11 ppm/° C.

FIG. 2is a schematic diagram of an exemplary process chamber200for use in connection with some embodiments of the present invention. In some embodiments, the process chamber200may be one of a plurality of chambers combined to form a multi-chamber processing system (e.g., a cluster tool). In some embodiments, the process chamber200may be a deposition chamber, for example, a physical vapor deposition (PVD) chamber. An exemplary process chamber and a cluster tool that may be modified in accordance with the present invention are described in previously incorporated U.S. Provisional Patent Application 61/099,090, filed Sep. 22, 2008, and entitled “SHUTTER DISK AND SYSTEM WITH SHUTTER DISK.”

The process chamber200includes a chamber body202and a lid assembly204that defines an evacuable process volume206. The chamber body202generally includes sidewalls208and a bottom210. The sidewalls generally contain a plurality of apertures that include an access port, pumping port and a shutter disk port212(access and pumping ports not shown). A sealable access port (not shown) provides for entrance and egress of the substrate214from the process chamber100. The pumping port is coupled to a pumping system (not shown) that evacuates and controls the pressure within the process volume206. The shutter disk port212is configured to allow at least a portion of a shutter disk100therethrough when the shutter disk100is in the cleared position. A housing216generally covers the shutter disk port212to maintain the integrity of the vacuum within the process volume206.

The lid assembly204of the chamber body202generally supports an annular shield218suspended therefrom that supports a shadow ring220. The shadow ring220is generally configured to confine deposition to a portion of the substrate214exposed through the center of the shadow ring220. The lid assembly204generally comprises a target222and a magnetron224.

The target222provides material that is deposited on the substrate214during the deposition process while the magnetron224enhances uniform consumption of the target material during processing. The target222and substrate support226are biased relative each other by a power source228. An inert gas, for example, argon, is supplied to the process volume206from a gas source230. A plasma is formed between the substrate214and the target222from the gas. Ions within the plasma are accelerated toward the target222and cause material to become dislodged from the target222. The dislodged target material is attracted towards the substrate214and deposits a film of material thereon.

The substrate support226is generally disposed on the bottom210of the chamber body202and supports the substrate214during processing. A shutter disk mechanism232is generally disposed proximate the substrate support226. The shutter disk mechanism232generally includes a blade234that supports the shutter disk100and an actuator236coupled to the blade234by a shaft238.

The blade234may be moved between the cleared position shown inFIG. 2and a second position that places the shutter disk100substantially concentric with the substrate support226. In the second position, the shutter disk100may be transferred (by utilizing the lift pins) to the substrate support226during the target burn-in and chamber pasting processes. The blade234is returned to the cleared position during the target burn-in and chamber pasting processes. The actuator236may be any device that may be adapted to rotate the shaft238through an angle that moves the blade234between the cleared and second positions.