CA1277955C - Anode for magnetic sputtering - Google Patents
Anode for magnetic sputteringInfo
- Publication number
- CA1277955C CA1277955C CA000493547A CA493547A CA1277955C CA 1277955 C CA1277955 C CA 1277955C CA 000493547 A CA000493547 A CA 000493547A CA 493547 A CA493547 A CA 493547A CA 1277955 C CA1277955 C CA 1277955C
- Authority
- CA
- Canada
- Prior art keywords
- anode
- cathode
- sputtering
- metal mesh
- sputtering surface
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Abstract
Abstract of the Disclosure An improved anode system for producing coatings by magnetic sputtering is disclosed, comprising a metal mesh anode structure of expanded metal. It is particularly applicable to an elongated rectangular cathode of the type typically used in a scanning magnetron sputtering coating apparatus.
A magnetic field forms a magnetic flux tunnel for the sputtered material over a closed loop region of the sputtering surface. The metal mesh anode is spaced from the major dimension of the tunnel. The mesh design allows free flow of the reactive atmosphere in the sputtering chamber and the anode can be oriented perpendicularly to the sputtering surface.
A magnetic field forms a magnetic flux tunnel for the sputtered material over a closed loop region of the sputtering surface. The metal mesh anode is spaced from the major dimension of the tunnel. The mesh design allows free flow of the reactive atmosphere in the sputtering chamber and the anode can be oriented perpendicularly to the sputtering surface.
Description
~Z7~9~
Back round of the Invention g Thls lnventlon relates generally to the art of magnetic ~putterlng, ant more partlcularly to the art of anode deslgns for magnetlc sputterlng.
U.S. Patent No. 4,166,018 to Chapln descrlbes a sputtering apparatu6 ln whlch a magnetlc fleld is formet ad~acent a planar sputterlng surface, the flelt comprlslng archlng lines of flux over a closet loop ero~ion reglon on the sputtering surface. Chapin teaches that the configuratlon of the anode 18 relatlvely unlmportant, but lt ls preferred that the snote be of relatlvely small slze comparet to the cathote surface. In the lllustratet embotlment, the anode comprlses a bar of relatlvely small cross-sectlon whlch extends around the cathode spacet from lts perlmeter.
In prlor art llterature on magnetlc sputterlng, the deslgn of the anode ~ystem 18 typically elther lgnored or tlsmlsset as relatlvely unlmportant. However, lt 18 tlscloset ln U.S. Patent No. ~,~ to Glllery et al that approprlate anote deslgn is essential to attaining i very unlform sputtered fllms, particularly in reactive sputtering processes, ant most especially when depositing insulating layers, such as tltanlum oxlte.
~ ~7 ~' ~;~7795~;
Here described ls an improved anode system utillzing a metal mesh rather than a metal plate as the anode. Because the mesh design allows free flow of the reactive atmosphere in the sputtering chamber, the mesh anode may be oriented vertically instead of horizontally. The new anode system is particularly well designed for use with an elongated rectangular cathode of the type typically used in a scanning magnetron sputtering coating apparatus.
The anode system may comprise a single anode, but generally comprises two separate anode mesh structures disposed on opposite sides of the cathode or on opposite sides of the substrate. The configuration, dimensions and placement of the anodes are very important. For a uniform thickness coating, each anode sbould be at least substantially the same length as the dimenslon which it parallels of the substrate to be coated, typically about the same length as the cathode. For a gradient thickness coating, the length and width of the anote i8 determined by the pattern of coating desired. The thickness of the anode i9 preferably minimal. As expanded metal mesh of the desired configuration provides a particularly suitable anode structure.
In a preferred embodiment of the present invention, an expanded metal mesh anode system is positioned along the cathode oriented with the effective surace of the anote perpendicular to the sputtering surface of the cathode and the surfsce of the substrate to be coated. In addition to permitting vertical orientat~on of the anode, the new metal mesh anode design reduces or eliminates the need for cooling of the anode.
In accordance with the invention, there is provided in an apparatus for coating a substrate compr,ising a cathode havlng a substantially planar surface consisting of a material to be sputtered, magnet means for produclng a magnetlc ficlt havlng llnes of flux wlllch extend ln a curve from sald sputterlng surface and return thereto to form a magnetlc tunnel over a closet loop erosion region on sald 6putterlng surface, an anode positlonet to produce an acceleratlng electric fleld ad~acent sald sputterlng surface for produclng a glow dlscharge conflned by sald magnetlc fleld to the reglon adjacent sald 6putterlng surface and wlthln said magnetlc tunnel, and means for connectlng sald cathode and sald anode to a source of electrlcal potentlal, the lmprovement wheroin said anode comprises a metal me~h otructure spaced feom the ma~or dlmenslon of &ald magnetlc tunnel out~lde the zone of glow dlscharge conflnement Brlef Description of the Drawing Figure 1 lllustrates an elongated rectangular cathode 1 with a pair of elongated mesh anodes 2 positioned on opposite sides of the cathode 1, and oriented with the effective surfaces of the anodes perpendicular to the sputtering surface of the cathode 1.
Detailed Description of the Preferred Embodiments In a typical co~merclally available magnetic sputtering coating apparatus, the anode supplled consists of an elongated loop of copper tubing di~posed on one slde of an elongated rectangulas cathode. In operatlon, this system deposits a coating of extremely poor uniformity.
For example, when sputterlng a titanium oxide film from a titanium metal cathote 40 inches (1 meter) long and 6 inches (15 centlmeters) wlde scanning over a distance of 24 inches (61 centimeters) at a dlstance of 3 inches (7.6 centimeters) from the substrate in an atmosphere of 13 percent oxygen in argon at an average current density of 0.0625 amps per square inch (0.0097 2mps pe~ square centimeter), the thickness of the coatlng varies by 30 percent. Typically, a thick band of coating is formed along one edge of the substrate and bands of varying thickness are formet in the center.
In the development leading to the present invention, it was deduced from a series of experiments that as electrons leave the face of the cathode and travel in the magnetic tunnel created by the magnetlc field developed by the sputtering apparatus, they begin to lose energy and are attracted to the anode. As a result, it was discovered, the shape of the anode and its proxlmity to the magnetic tunnel tend to affect the current flow along the cathode, thereby determine the rate of deposition of the coating, and ultimately control the film thickness.
~779~
Metal mesh anode designs en~bodying the presënt invention oriented vertically in relation to a horizontal cathode provide uniform current flow along the cathode, which promotes a unlform deposi~ion rate, which results in a uniorm fllm. Symmetrlcal metal mesh anode designs for depo~iting uni~orm films embodying the invention comprise a pair of anodes dlsposed on opposite sides of a cathode, whereln the ma~or dimension (length) of the anodes is substantially equal to the ma~or dimension (length) of the cathode, and the spaclng between the cathode and each anode i8 uniform along its length, The effective 1 surfaces of the anodes are perpendicular to the sputtering surface of the cathode.
In one preferred embodlment of the present invention, a pair of elongated rectangular anodes 2 is disposed on opposite sides of an elongated rectangular cathode 1 as in Figure 1. The anodes typically comprlse an expanded mesh of mild steel, which withstands the heat bulld-up incltental to cathdde sputterlng without requiring cooling.
The new metal mesh anode deslgns may also be shaped to provlde for the deposition of a desired gradlent film.
Although the present invention has been discussed in detail above with respect to a titanium cathode, steel mesh anodes and a scanning apparatus, various other target materials, such as indium, may be used, as well as other expanded metals and configurations for the anote. Either scanning or stationary cathodes may be used to produce either uniform or gradient coatings. The present lnvention will be further unterstood from the descrlption of the specific example which follows.
7795~;
Example I
A stationary titanium cathode with a sputtering surface measuring 6 by 40 inches (15 by 102 centimeters) is spaced about 3 inches (about 7.6 centimeters) from a glass substrate having approximately the same dimensions. A pair of mild steel expanded mesh anodes shaped and positioned as lllustrated in Figure 1 is used in this example. The cathode is sputtcred at an average current density of 0.0625 amps per square inch (0.0097 amps per square centimeter) for about 5 minutes in an atmosphere of 13 percent oxygen in argon at a pressure of 6 x 10 4 Torr to produce a uniform titanium oxide film on the glass surface.
The above example is offered only to illustrate the present invention. Other anode shapes, sizes and positions may be employed to form coatlngs. Whlle the example above employs a stationary cathode, a scanning cathode or moving substrate may be employed. The cathode, anode and substrate may be comprised of a variety of materials known in the art. The scope of the inventlon ls defined by the following claims.
Back round of the Invention g Thls lnventlon relates generally to the art of magnetic ~putterlng, ant more partlcularly to the art of anode deslgns for magnetlc sputterlng.
U.S. Patent No. 4,166,018 to Chapln descrlbes a sputtering apparatu6 ln whlch a magnetlc fleld is formet ad~acent a planar sputterlng surface, the flelt comprlslng archlng lines of flux over a closet loop ero~ion reglon on the sputtering surface. Chapin teaches that the configuratlon of the anode 18 relatlvely unlmportant, but lt ls preferred that the snote be of relatlvely small slze comparet to the cathote surface. In the lllustratet embotlment, the anode comprlses a bar of relatlvely small cross-sectlon whlch extends around the cathode spacet from lts perlmeter.
In prlor art llterature on magnetlc sputterlng, the deslgn of the anode ~ystem 18 typically elther lgnored or tlsmlsset as relatlvely unlmportant. However, lt 18 tlscloset ln U.S. Patent No. ~,~ to Glllery et al that approprlate anote deslgn is essential to attaining i very unlform sputtered fllms, particularly in reactive sputtering processes, ant most especially when depositing insulating layers, such as tltanlum oxlte.
~ ~7 ~' ~;~7795~;
Here described ls an improved anode system utillzing a metal mesh rather than a metal plate as the anode. Because the mesh design allows free flow of the reactive atmosphere in the sputtering chamber, the mesh anode may be oriented vertically instead of horizontally. The new anode system is particularly well designed for use with an elongated rectangular cathode of the type typically used in a scanning magnetron sputtering coating apparatus.
The anode system may comprise a single anode, but generally comprises two separate anode mesh structures disposed on opposite sides of the cathode or on opposite sides of the substrate. The configuration, dimensions and placement of the anodes are very important. For a uniform thickness coating, each anode sbould be at least substantially the same length as the dimenslon which it parallels of the substrate to be coated, typically about the same length as the cathode. For a gradient thickness coating, the length and width of the anote i8 determined by the pattern of coating desired. The thickness of the anode i9 preferably minimal. As expanded metal mesh of the desired configuration provides a particularly suitable anode structure.
In a preferred embodiment of the present invention, an expanded metal mesh anode system is positioned along the cathode oriented with the effective surace of the anote perpendicular to the sputtering surface of the cathode and the surfsce of the substrate to be coated. In addition to permitting vertical orientat~on of the anode, the new metal mesh anode design reduces or eliminates the need for cooling of the anode.
In accordance with the invention, there is provided in an apparatus for coating a substrate compr,ising a cathode havlng a substantially planar surface consisting of a material to be sputtered, magnet means for produclng a magnetlc ficlt havlng llnes of flux wlllch extend ln a curve from sald sputterlng surface and return thereto to form a magnetlc tunnel over a closet loop erosion region on sald 6putterlng surface, an anode positlonet to produce an acceleratlng electric fleld ad~acent sald sputterlng surface for produclng a glow dlscharge conflned by sald magnetlc fleld to the reglon adjacent sald 6putterlng surface and wlthln said magnetlc tunnel, and means for connectlng sald cathode and sald anode to a source of electrlcal potentlal, the lmprovement wheroin said anode comprises a metal me~h otructure spaced feom the ma~or dlmenslon of &ald magnetlc tunnel out~lde the zone of glow dlscharge conflnement Brlef Description of the Drawing Figure 1 lllustrates an elongated rectangular cathode 1 with a pair of elongated mesh anodes 2 positioned on opposite sides of the cathode 1, and oriented with the effective surfaces of the anodes perpendicular to the sputtering surface of the cathode 1.
Detailed Description of the Preferred Embodiments In a typical co~merclally available magnetic sputtering coating apparatus, the anode supplled consists of an elongated loop of copper tubing di~posed on one slde of an elongated rectangulas cathode. In operatlon, this system deposits a coating of extremely poor uniformity.
For example, when sputterlng a titanium oxide film from a titanium metal cathote 40 inches (1 meter) long and 6 inches (15 centlmeters) wlde scanning over a distance of 24 inches (61 centimeters) at a dlstance of 3 inches (7.6 centimeters) from the substrate in an atmosphere of 13 percent oxygen in argon at an average current density of 0.0625 amps per square inch (0.0097 2mps pe~ square centimeter), the thickness of the coatlng varies by 30 percent. Typically, a thick band of coating is formed along one edge of the substrate and bands of varying thickness are formet in the center.
In the development leading to the present invention, it was deduced from a series of experiments that as electrons leave the face of the cathode and travel in the magnetic tunnel created by the magnetlc field developed by the sputtering apparatus, they begin to lose energy and are attracted to the anode. As a result, it was discovered, the shape of the anode and its proxlmity to the magnetic tunnel tend to affect the current flow along the cathode, thereby determine the rate of deposition of the coating, and ultimately control the film thickness.
~779~
Metal mesh anode designs en~bodying the presënt invention oriented vertically in relation to a horizontal cathode provide uniform current flow along the cathode, which promotes a unlform deposi~ion rate, which results in a uniorm fllm. Symmetrlcal metal mesh anode designs for depo~iting uni~orm films embodying the invention comprise a pair of anodes dlsposed on opposite sides of a cathode, whereln the ma~or dimension (length) of the anodes is substantially equal to the ma~or dimension (length) of the cathode, and the spaclng between the cathode and each anode i8 uniform along its length, The effective 1 surfaces of the anodes are perpendicular to the sputtering surface of the cathode.
In one preferred embodlment of the present invention, a pair of elongated rectangular anodes 2 is disposed on opposite sides of an elongated rectangular cathode 1 as in Figure 1. The anodes typically comprlse an expanded mesh of mild steel, which withstands the heat bulld-up incltental to cathdde sputterlng without requiring cooling.
The new metal mesh anode deslgns may also be shaped to provlde for the deposition of a desired gradlent film.
Although the present invention has been discussed in detail above with respect to a titanium cathode, steel mesh anodes and a scanning apparatus, various other target materials, such as indium, may be used, as well as other expanded metals and configurations for the anote. Either scanning or stationary cathodes may be used to produce either uniform or gradient coatings. The present lnvention will be further unterstood from the descrlption of the specific example which follows.
7795~;
Example I
A stationary titanium cathode with a sputtering surface measuring 6 by 40 inches (15 by 102 centimeters) is spaced about 3 inches (about 7.6 centimeters) from a glass substrate having approximately the same dimensions. A pair of mild steel expanded mesh anodes shaped and positioned as lllustrated in Figure 1 is used in this example. The cathode is sputtcred at an average current density of 0.0625 amps per square inch (0.0097 amps per square centimeter) for about 5 minutes in an atmosphere of 13 percent oxygen in argon at a pressure of 6 x 10 4 Torr to produce a uniform titanium oxide film on the glass surface.
The above example is offered only to illustrate the present invention. Other anode shapes, sizes and positions may be employed to form coatlngs. Whlle the example above employs a stationary cathode, a scanning cathode or moving substrate may be employed. The cathode, anode and substrate may be comprised of a variety of materials known in the art. The scope of the inventlon ls defined by the following claims.
Claims (5)
1. In an apparatus for coating a substrate comprising a cathode having a substantially planar surface consisting of a material to be sputtered, magnet means for producing a magnetic field having lines of flux which extend in a curve from said sputtering surface and return thereto to form a magnetic tunnel over a closed loop erosion region on salt sputtering surface, an anode positioned to produce an accelerating electric field adjacent said sputtering surface for producing a glow discharge confined by said magnetic field to the region adjacent said sputtering surface and within said magnetic tunnel, and means for connecting said cathode and said anode to a source of electrical potential, the improvement wherein said anode comprises a metal mesh structure spaced from the major dimension of said magnetic tunnel outside the zone of glow discharge confinement.
2. The improved apparatus according to claim 1, wherein the cathode is of elongated rectangular shape, and the anode comprises a pair of metal mesh anode structures positioned on opposite sides of the cathode.
3. The improved apparatus according to claim 2, wherein each anode structure is of elongated shape substantially the same length as the dimension of the substrate surface to be coated which it parallels.
4. The improved apparatus according to claim 3, wherein the effective surfaces of the metal mesh anode structures are substantially perpendicular to the sputtering surface of the cathode.
5. The improved apparatus according to claim 1, said anode comprising a metal mesh structure asymmetrically designed with respect to said magnetic tunnel to produce a gradient sputtered coating.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US663,913 | 1984-10-23 | ||
| US06/663,913 US4600490A (en) | 1984-01-17 | 1984-10-23 | Anode for magnetic sputtering |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1277955C true CA1277955C (en) | 1990-12-18 |
Family
ID=24663742
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000493547A Expired - Lifetime CA1277955C (en) | 1984-10-23 | 1985-10-22 | Anode for magnetic sputtering |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1277955C (en) |
-
1985
- 1985-10-22 CA CA000493547A patent/CA1277955C/en not_active Expired - Lifetime
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |