Loading patent…
AssigneeVarian Associates, Inc.
InventorsDonald R. Boys, Walter E. Graves
Estimating the term…
A novel magnetron sputter coating source is disclosed in which magnetic sputter targets containing relatively large inventories of usable material may be employed. This coating source may also be used efficiently and effectively with sputter target materials having properties which range from nonmagnetic to highly ferromagnetic. Use of an electromagnetic coil with a widely adjustable energizing current, rather than permanent magnets, allows a wide range of magnetic properties to be accommodated. Electrical impedance of the glow discharge is readily controlled using the current flow through the electromagnetic coil, allowing, for example, operation at desired values of voltage and current throughout the life of the sputter target. In addition, a momentary increase in electromagnet coil current can be used to achieve ignition of the glow discharge at a desired sputter gas operating pressure which is below the sputter gas pressure at which the glow discharge can normally be readily ignited. Also, use of the electromagnetic coil permits an easy conversion of the magnetron sputter coating source to a nonmagnetic diode apparatus. The use of a Hall probe positioned adjacent and below the sputter target near the region of maximum erosion is disclosed. The Hall probe voltage, which is proportional to the magnetic field intensity at the Hall probe position, may be measured throughout sputter target life to provide an independent means of assessing the approach to end of useful life. A novel sputter target cooling means is disclosed in which a water chamber below the sputter target is divided into inlet and outlet portions by a septum. The flow of water through a narrow gap between the septum and the sputter target leads to highly effective heat transfer, which is also highly uniform along the peripheral path of intense heating of the sputter target.
A magnetron sputter coating source comprising an anode, a cathode means including means for mounting a magnetic sputter target, and a magnetic field means including an electromagnet coil, a yoke, and a pair of polepieces separated by a spatial gap and joined to said yoke, said yoke and polepieces being made of materials of high magnetic permeability and high saturation magnetization, said magnetic sputter target being mounted so as to be positioned atop said polepieces, said gap and magnetic sputter target being configured and positioned so the target completely bridges said spatial gap, whereby a continuous magnetic path between said polepieces is provided through said target, an electric current flowing in said electromagnet coil causing magnetic field lines to be established in said yoke, polepieces, and magnetic sputter target, said coil current having a critical value, substantially all of said magnetic field lines being confined to the interior of said yoke, polepieces, and magnetic sputter target when said coil current is less than said critical value, a magnetically saturated portion of said magnetic sputter target occurring when said coil current is greater than said critical value, whereby a magnetic gap is established in said magnetic sputter target, said magnetic gap allowing fringing magnetic field lines to be established above and below said magnetic sputter target in the vicinity of said magnetic gap, said coil current having a required value, said required value being sufficiently greater than said critical value that said fringing magnetic field lines above said magnetic sputter target having required intensities may be established, thereby allowing a magnetically confined and magnetically enhanced glow discharge to be established above said magnetic sputter target in a region adjacent said magnetic gap.
A magnetron sputter coating source comprising an anode, a cathode means including a sputter target, and a magnetic field means including an electromagnetic net coil, a yoke, and a pair of polepieces separated by a spatial gap and joined to said yoke, said yoke and polepieces being made of materials of high magnetic permeability and high saturation magnetization, said sputter target being positioned atop said polepieces and bridging said spatial gap, said spatial gap allowing magnetic field lines to be established for magnetically confining and magnetically enhancing a glow discharge above said sputter target, shapes and intensities of said magnetic field lines depending on an electric current flowing in said electromagnet coil and also depending on a material of which said sputter target is made, said coil current having a required first value for desired glow discharge establishment when said sputter target material is nonmagnetic, said coil current having a required second value for desired glow discharge establishment when said sputter target material is magnetic, said required second value being greater than said required first value to provide magnetic saturation of a portion of said magnetic sputter target, thereby creating a magnetic gap in said magnetic sputter target across which glow discharge confining and enhancing magnetic fields above said magnetic sputter target can be established.
A magnetron sputter coating source comprising an anode, a cathode means including means for mounting a sputter target, a means for cooling said sputter target, and a magnetic field means including a yoke and a pair of polepieces separated by a gap and joined to said yoke, said polepiece gap being configured to form a closed peripheral path lying generally in a horizontal plane, said yoke and polepieces being made of magnetic materials, said sputter target being positioned atop said polepieces and bridging said polepiece gap, a vacuum seal being provided between a bottom surface of said sputter target and top surfaces of said polepieces, said polepiece gap allowing magnetic field lines to be established for magnetically confining and magnetically enhancing a glow discharge above said sputter target, a top surface of said sputter target being subject to intense bombardment by positive ions produced in said glow discharge, said intense ion bombardment causing intense heating of said sputter target, said intense ion bombardment being concentrated in a region generally above said polepiece gap, forming thereby a peripheral path of intense heating of said sputter target, said cooling means including a water chamber, a portion of said sputter target bottom surface between said polepiece gap being part of the interior surface of said water chamber, said water chamber being divided into inlet and outlet portions by a septum, said septum being positioned below said sputter target bottom surface and directly beneath said region of intense ion bombardment, said septum being configured to form a closed peripheral path corresponding to said polepiece gap peripheral path, a narrow gap being provided between a top surface of said septum and said sputter target bottom surface, said narrow gap providing a high impedance to water flow, said narrow gap causing cooling water flowing from said inlet portion to said outlet portion of said water chamber to make intimate thermal contact with said sputter target bottom surface, said intimate thermal contact being substantially uniform over said polepiece gap peripheral path, whereby substantially uniform cooling of said sputter target is achieved along said peripheral path of intense heating of said sputter target.
A magnetron sputter coating source as in claim 32 including also a Hall probe for measuring a magnetic field intensity at a position of said Hall probe, said Hall probe being positioned in a small portion of said peripheral path of said septum, a close fit being established between side walls of said Hall probe and adjacent ends of said septum, said close fit preventing a significant perturbation in the flow of cooling water through said narrow gap between said septum top surface and said sputter target bottom surface, a second narrow gap being established between a top surface of said Hall probe and said sputter target bottom surface, said second narrow gap being chosen to provide a high impedance to water flow which is substantially the same as said high impedance provided by said narrow gap between said septum top surface and said sputter target bottom surface, whereby despite inclusion of said Hall probe the effectiveness of said cooling means is preserved.
A magnetically enhanced sputter coating source comprising anode means, cathode means, magnetic means for forming a magnetic field in the proximity of said cathode means, means for measuring magnetic field strengths, said measuring means being mounted in a position to provide a measurement of said magnetic field during operation of said source.
A magnetically enhanced sputter coating source comprising anode means, cathode means, magnetic field means comprising a central polepiece forming the center axis of said source, an electromagnet coil coaxially surrounding said central polepiece, and an annular polepiece coaxially surrounding said coil, said polepieces being configured to form coplanar end surfaces having annular pole faces spaced apart to form a planar annular nonmagnetic gap.
A magnetically enchanced sputter coating source comprising magnetic means including inner and outer annular ferromagnetic members spaced apart radially, said annular ferromagnetic members forming polepieces separated by an annular space, electromagnet coil means positioned in the space between said annular members, anode means supported in the space within said inner annular member, and said polepieces being electrically insulated from said anode means to form cathode means.
A method of operating a magnetron sputter coating source having an anode, a cathode means including a magnetic sputter target, and a magnetic field means including an electromagnet coil, a yoke, and a pair of polepieces separated by a spatial gap and joined to said yoke, said yoke and polepieces being made of materials of high magnetic permeability and high saturation magnetization, the method comprising positioning said magnetic sputter target atop said polepieces so the target completely bridges said spatial gap, whereby a continuous magnetic path between said polepieces is provided through said target, applying an electric current to said electromagnet coil so magnetic field lines are established in said yoke, polepieces, and magnetic sputter target, said coil current having a critical value, substantially all of said magnetic field lines being confined to the interior of said yoke, polepieces, and magnetic sputter target when said coil current is less than said critical value, and establishing a magnetic gap in said magnetic sputter target by adjusting said coil current to be greater than said critical value so a magnetically saturated portion of said magnetic sputter target occurs, fringing magnetic field lines thereby being established above and below said magnetic sputter target in the vicinity of said magnetic gap.
A method of operating a magnetron sputter coating source including:
A magnetron sputter coating source comprising an anode, cathode means including means for mounting a sputter target, means for cooling said sputter target, and a magnetic field means including a yoke and a pair of polepieces separated by a gap and joined to said yoke, said polepiece gap being configured to form a closed peripheral path lying generally in a horizontal plane, said yoke and polepieces being made of magnetic materials, said sputter target being positioned atop said polepieces, a vacuum seal being provided between a bottom surface of said sputter target and top surfaces of said polepieces, a top surface of said sputter target being subject to intense bombardment by positive ions produced in a glow discharge established in the source, said intense ion bombardment causing intense heating of said sputter target, said intense ion bombardment being concentrated in a region generally above said polepiece gap thereby forming a peripheral path of intense heating of said sputter target, said cooling means including:
A method of operating a sputtering apparatus as a magnetron sputter coating source for a substrate or as a nonmagnetic diode sputtering device for a workpiece, the apparatus including a target cathode, an anode, means for forming a glow discharge, and an electromagnet, the method comprising applying a DC voltage between the anode and cathode while a current is applied to the electromagnet and the glow discharge is formed to cause the apparatus to operate as a magnetron sputter coating source so atoms are deposited on the substrate, and applying a DC voltage between the anode and cathode while no current is applied to the electromagnet and the glow discharge is formed to cause the apparatus to operate as a nonmagnetic diode sputtering device so atoms are incident on the work piece.
A magnetically enhanced sputter coating source comprising anode means, cathode means, means for forming a magnetic field in proximity to said cathode means, magnetic field strength measuring means mounted in a position to provide a measurement of the formed magnetic field during operation of said coating source.
A method of controlling a sputter coating depositing apparatus including a magnetic target cathode, an anode and a plasma, ionizing electrons for the plasma having a tendency to be confined in proximity to an emitting surface of the target by a magnetic field having lines of flux adjacent the emitting surface, the confining magnetic field intersecting electric field lines extending between the anode and cathode, atoms from the emitting surface being deposited on a substrate, the method comprising applying a magnetic field to the target, the magnetic field having an intensity sufficient to saturate magnetic material of the target and establish a magnetic fringing field in proximity to the emitting surface, the magnetic fringing field being the confining magnetic field, and controlling the magnetic field in response to an indication of plasma impedance.
A method of controlling a process for sputter coating substrates with an apparatus including a target cathode, an anode and means for establishing a glow discharge between the anode and cathode, the improvement comprising sensing a magnetic field in proximity to the target cathode to sense a fringing field of the target cathode and controlling a function of the plasma impedance in response to the sensed magnetic field.
Dependencies are inferred from the claim text.