Patent Application
20120111270
This application relates to materials deposition on a substrate and removal of materials from a surface in the presence of a plasma gas.
Material deposition is widely used in window glass coating, flat panel display manufacturing, coating on flexible films, coating of magnetic materials on hard disks, industrial surface coating, semiconductor wafer processing, photovoltaic panels, and other applications. Removal of materials from a deposition source and/or a substrate is also used in these applications. Plasma is often used to enhance material deposition and material removal in many applications.
One example is material deposition in which target materials are sputtered or vaporized from a source and deposited on a substrate. One desirable feature for material deposition is to maximize the utilization and to minimize waste of target materials. Another desirable feature for material deposition is to achieve uniform deposition across the substrates, preferably at low pressure which requires high plasma density.
In another example, chemical gases such as silane and hydrogen are ionized in plasma and form solid deposition on substrate. One desirable feature for solid deposition is to achieve uniform plasma density across substrate surface, preferably high density plasma to enhance the breakup efficiency of the chemicals.
Another example relates to the removal of materials from substrate or/and deposition sources. One desirable feature is to achieve uniform plasma at a low pressure and high plasma density. Another desirable feature is to process more substrate area in a given volume.
There is therefore a need to provide uniform plasma density and thus material deposition for a wide range of applications involving material depositions and removals.
The presently disclosed systems and methods can provide improved uniformity in large-area sputter deposition, plasma enhanced chemical vapor deposition, low pressure sputter etch, plasma etch and cleaning, and ion assisted evaporation.
The presently disclosed systems and methods can provide high deposition throughput by depositing on a multiple of substrate in parallel and provide deposition on both sides of a substrate if necessary.
The disclosed systems can provide efficient and uniform material deposition in a wide range of industrial applications such as thin-film deposition, substrate etching, sputtering using DC (direct current)/RF (radio frequency) diode or magnetron, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), sputter etch, plasma etch, or reactive ion etch.
The disclosed systems can improve target utilization and reduce material cost by using targets that are smaller than the substrates. The disclosed system can also improve the collection of the sputtered materials by enclosing the targets by a plurality of substrates. The disclosed systems can utilize thick targets to allow longer deposition cycles between target changes, thus reducing scheduled system down time. The disclosed magnetron source can improve target utilization and reduce target cost by reducing the unevenness in the erosion of the target.
In some implementations of the disclosed systems, sources can be positioned in a central region surrounded by a plurality of substrates with deposition surfaces facing the center. Particles, ions, atoms, molecules, etc can move outward from the sources to the substrate surfaces. The sources can be positioned close to each other to achieve the improved uniformity. The substrates can be placed adjacent to each other to achieve the most material collection of the source materials by the substrates.
The deposition and etch systems can provide deposition on large substrate while occupying relatively small footprint. The disclosed deposition and etch systems can simultaneously deposit on a plurality of large substrates. The substrates can be rigid or flexible. For example, the substrates can include webs that are fed in rolls.
The disclosed processing system can generate high sputtering rate for magnetic and ferromagnetic target materials. The disclosed processing system allows material compositions to be controlled and varied. The disclosed processing system also allows different processing such as sputtering and ion etching to be conducted on the same substrate in the same vacuum environment. The disclosed deposition and etch systems can use reduce the usages of energy, chemicals and other materials when compared to conventional processing system.
In one general aspect, the present invention relates to a plasma-enhanced substrate processing system which includes a magnetic-field generation unit that can create a substantially uniform magnetic field along an axial direction in a spatial region; a processing chamber in the spatial region and configured to house a first substrate; and a first planar source unit that can provide a deposition material, wherein the magnetic field can produce a plasma gas in the processing chamber, which enables the deposition material to be deposited on the first substrate.
Implementations of the system may include one or more of the following. The magnetic-field generation unit can include an electrical coil that can carry an electrical current therein and to produce substantially uniform magnetic field in the spatial region. The electrical coil can be outside and encircles the processing chamber, and wherein the spatial region is at least partially inside the electrical coil. The electrical coil can be inside the processing chamber, and wherein the spatial region is at least partially outside the electrical coil. The first planar source unit can include a first target comprising the deposition material and a sputtering surface, wherein the magnetic field can produce the plasma gas between the sputtering surface and the first substrate, wherein the deposition material is sputtered off the first target to be deposited on the first substrate via physical vapor deposition (PVD). The first planar source unit can include a gas distribution device that can provide the deposition material in a chemical vapor, wherein the magnetic field can produce the plasma gas between the gas distribution device and the first substrate, wherein the deposition material can be deposited on the first substrate in a plasma enhanced chemical vapor deposition (PECVD). The plasma-enhanced substrate processing system can further include a plurality of planar source units, including the first planar source unit, positioned in a first closed loop, wherein the processing chamber in the spatial region can house a plurality of substrates comprising the first substrate, wherein the plurality of substrates are positioned in a second closed loop, wherein the plurality of substrates can receive deposition materials from the plurality of source units. The magnetic-field generation unit can include a plurality of permanent magnets that form a third close loop, wherein the plurality of permanent magnets in the third close loop can be moved relative to the plurality of planar source units in the first closed loop. The first closed loop can be inside the second closed loop. The second closed loop can be inside the first closed loop. At least one of the first closed loop or the second closed loop can form a polygon when viewed in the axial direction. The first substrate can be provided as or on a flexible web. The magnetic-field generation unit can include two electrical coils can create a substantially uniform magnetic field along an axial direction in a spatial region between the two electrical coils.
In another general aspect, the present invention relates to a plasma-enhanced substrate processing system that include a magnetic-field generation unit that can create a substantially uniform magnetic field along an axial direction in a spatial region, a processing chamber in the spatial region and configured to house a first substrate, wherein the processing chamber can house a first group of substrates and a second group of substrates, wherein the first group of substrate can include a first substrate; a first group of source units including a first source unit, wherein the first group of source units can be positioned in a first closed loop, wherein the first group of substrates can be positioned in a second closed loop, wherein the magnetic field can produce a plasma gas in the processing chamber to enable deposition materials from the first group of source units to be deposited on the first group of substrates; and a second group of source units positioned in a third closed loop, wherein the second group of substrates can be positioned in a fourth closed loop, wherein the magnetic field can produce a plasma gas in the processing chamber to enable deposition materials from the second group of source units to be deposited on the second group of substrates.
Implementations of the system may include one or more of the following. The first closed loop, the second closed loop, the third closed loop, and the fourth closed loop can be nested one in another. The magnetic-field generation unit can include an electrical coil that can carry an electrical current therein and to produce substantially uniform magnetic field in the spatial region. The electrical coil can be outside and can encircle the processing chamber, and wherein the spatial region is at least partially inside the electrical coil. The electrical coil can be inside the processing chamber, and wherein the spatial region is at least partially outside the electrical coil. The first source unit can include a first target comprising the deposition material and a sputtering surface, wherein the magnetic field can produce the plasma gas between the sputtering surface and the first substrate to allow the deposition material to be sputtered off the first target to be deposited on the first substrate via physical vapor deposition (PVD). The first source unit can include a gas distribution device that can provide the deposition material in a chemical vapor, wherein the magnetic field can produce the plasma gas between the gas distribution device and the first substrate to allow the deposition material to be deposited on the first substrate in a plasma enhanced chemical vapor deposition (PECVD). The first closed loop can be inside the second closed loop. The second closed loop can be inside the first closed loop.
The details of one or more embodiments are set forth in the accompanying drawings and in the description below. Other features, objects, and advantages of the invention will become apparent from the description and drawings, and from the claims.
Referring to
The inner chamber walls 121 and the outer chamber walls 125 can be aligned substantially along a direction 175, which can be defined as the vertical direction. As shown in
A plurality of substrates 115 can be held on the outer chamber walls 125. A plurality of targets 110 can be held on the inner chamber walls 121. The targets 110 and the substrates 115 can be planar. The substrates 115 and the targets 110 can be positioned within the processing chamber 120 and have surfaces facing the space 150 that can be evacuated to a vacuum environment. Each target 110 includes a sputtering surface 112 opposing a deposition surface 117 on a substrate 115. The sputtering surface 112 can be substantially flat and parallel to the vertical direction. The sputtering surface 112 can also have other shapes such as a curved surface, or a surface not parallel to the direction 175. For viewing simplicity, the vacuum envelope is not fully illustrated in
The target 110 and the substrate 115 can be respectively held on opposing inner chamber wall 121 and outer chamber wall 125. The targets 110 and the substrate 115 can be arranged such that the sputtering surface 112 is substantially parallel to the deposition surfaces 117 in at least lateral dimension. The outer chamber walls 125 can form an enclosure surrounding the substrates 115 and the targets 110.
A plasma gas can be generated by an electric voltage, preferably in radio frequency (RF), applied across each pair of the targets 110 and the substrates 115. The substrate 115 can be moved by a transport mechanism 170. As shown in the cross-sectional view in
In some embodiments, the targets 110 can form an inner closed loop around the space 150 which allows the excited electrons near the sputtering surfaces of the targets 110 to travel in a closed loop around the space 150. Similarly, the substrates 115 can form an outer closed loop around the space 150 outside of the inner closed loop formed by the targets. The closed loop of substrates ensures effective collection of materials sputtered off the targets.
The permanent magnet 130a and 130b can form a closed loop that forms a magnetic field in a closed loop. The closed loop can be formed over a single target 110, or over the plurality of targets 110. In some embodiments, the permanent magnets 130a and 130b can form a closed magnetic loop in the plane that is perpendicular to the direction 175. The closed magnetic loop is adjacent to the closed loop formed by the targets. The magnetic in the closed loop can be moved by a transport mechanism (not shown) to scan across the targets 110 along the direction 175. The closed loop of permanent magnets around the processing chamber can achieve high utilization of the target materials because no magnetic return path is required at each target. In contrast, a conventional magnetron requires the return path for a target, which usually produces a closed loop erosion groove on the sputtering surface of the target and cannot fully erode the area at the edges adjacent to neighboring targets, which is a major cause for target waste.
The above described magnetic enhance plasma can perform sputtering deposition, PECVD, sputter etch, plasma etch, reactive ion etch, and ion assisted evaporation.
In some embodiments, the plasma-enhanced substrate processing system 100 can be further improved by using non-local magnetic fields (such as the ones formed by the magnetrons behind the targets), which removes the needs for a transport mechanism (not shown) that scans the magnetron relative to the target. The non-local magnetic fields can also improve sputtering and deposition uniformities, and can improve target material utilization, in comparison to many conventional deposition systems.
Referring to
The magnetic-field generation unit 190 is capable of producing a uniform magnetic field in a spatial region in which the processing chamber 120 is positioned. In other words, the processing chamber 120 is immersed in a substantially parallel magnetic field in the axial direction 180. As described in more detail below, the present invention is compatible with many configurations of magnetic generation sources. In some embodiments, the magnetic-field generation unit 190 includes an electric magnet comprising electrical coils 193 formed by conductive wires. The electrical coils 193 can be positioned outside of and encircling the processing chamber 120. The electrical coils 193 can substantially cover the full length of the processing chamber 120 along the axial direction 180.
In processing operation, a voltage is applied between the targets 110 and the substrates 115, which generates electrons moving at high speeds. The electrons are trapped by the Lorenz force F=eV×B in the magnetic field produced by the magnetic-field generation unit 190. The trapped electrons drift in the direction perpendicular to both the magnetic field and electron movement direction to form closed loops over the target surfaces when viewed in the axial direction (perpendicular to the viewing plane of
The electrical coils 193 produce a substantially uniform magnetic field therein, which are represented by the magnetic flux lines 195 in
The electric magnet in the present invention can be formed by electrical conductive wires that form a helical loop (e.g. coils). The conductive wire can be made of copper, aluminum, or other conductive materials. The electric magnet can be cooled by air, water, liquid nitrogen, liquid helium, or other media to lower the electric resistance. Superconductive electric wires can also be used to further lower resistance and to achieve high magnetic field. The typical magnetic field used ranges from 10 to 10,000 gauss. The circular electric magnet loop in the illustrations can be replaced with other shape such as polygon and other shapes of closed loops. In some embodiments, the magnetic-field generation unit can be formed by permanent magnets.
In some embodiments, the magnetic field can be produced by an internal magnetic-field generation unit and an external magnetic-field generation unit. As shown in
In some embodiments, referring to plasma-enhanced substrate processing system 400 in
In the present plasma-enhanced substrate processing systems, the substrates and the sputtering surfaces of the targets are usually inside a vacuum envelope. The backsides of the targets can be inside or outside of the vacuum envelope. In a plasma-enhanced substrate processing system 500, as shown in
Referring to
In the plasma-enhanced substrate processing systems 600 and 650 in
As shown in
In a plasma-enhanced substrate processing system shown in
In the presently disclosed plasma-enhanced substrate processing systems (e.g. as shown in
The substrates can also be placed back to back with or without space between the two substrates and receive deposition from two close-loop targets or process stations. The space between two substrates can be used to contain heater, voltage biasing devices, or gas outlets. This configuration can substantially increase the number of substrates that can be processed in each process chamber and thus reduce the cost of processing.
It should be noted that sputter deposition is used above only for the purpose of illustration. The disclosed plasma-enhanced substrate processing systems are also suitable for other processing techniques such as PECVD, sputter etches, plasma etches, and ion assisted evaporation.
In sputter etch application, the bias is negative relative to target surface, the energetic ions are attracted to bombard substrate surfaces and remove materials.
It is understood that the disclosed processing systems are compatible with other types of magnetic-field generation devices that can produce uniform magnetic field in a large spatial region in which the targets and the substrates are positioned. The disclosed processing systems are compatible with other positions of substrates, targets, and the magnetic-field generation devices. The disclosed processing systems are compatible with many different types of processing operations such as physical vapor deposition (PVD), thermal evaporation, thermal sublimation, sputtering, CVD, PECVD, ion etching, or sputter etching. The disclosed processing systems can include other components such as load lock, transport mechanism for the substrates, etc. without deviating from the spirit of the invention. The deposition materials can be provided by sputtering targets, gas distribution device, and other types of source units without deviating from the spirit of the invention.
The present application claims priority to pending U.S. Provisional Patent Application 61/411,549, entitled “Plasma processing chamber having enhanced deposition uniformity”, filed by the same inventor on Nov. 9, 2010, the disclosures of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61411569 | Nov 2010 | US |
