KR20000062587A - Method of manufacturing and refilling sputter targets by thermal spray for use and reuse in thin film deposition - Google Patents

Abstract

The method of the present invention is provided for manufacturing and recharging sputter targets for use and reuse in physical vapor deposition of thin films on semiconductor devices. The target base shells 12, 22 are coated by a thermal spray technique using the source material 14, 24 to be deposited as a thin film. The targets 10, 20 are refilled by reapplying the coating upon corrosion of the source material 14, 24 during the physical vapor deposition process. The method of the present invention can be used for any conventional sputter target 20 or for newly developed hollow cathode magnetron sputter target 10.

Description

Method of manufacturing and refilling sputter targets by thermal spray for use and reuse in thin film deposition}

The present invention relates to a method of manufacturing a sputter target for use in physical vapor deposition of a thin film on a semiconductor device, and to a method of recharging a sputter target for reuse.

In the semiconductor industry, faster and smaller chips are needed to handle ever-growing types of sophisticated applications. Thus, the semiconductor industry is moving towards mass products of 0.18 μm devices. In order to manufacture such devices, obvious changes in all manufacturing aspects, including new materials and manufacturing techniques, are required. 0.18 μm devices are smaller in size and have an increased proportion compared to current devices and represent an obvious challenge to current PVD and metallization technologies.

A new development in physical vapor deposition (PVD) technology that addresses the challenge of 0.18 μm devices is a vertical cathode cathode magnetron (HCM), a new class of high density plasma devices for use as ionized PVD sources for semiconductor device materials. This HCM sputter source is less expensive and has higher performance than conventional PVD technology.

When used in an IPVD environment, HCM technology facilitates more efficient production of ions of the target material that are directed at right angles to the substrate that is effectively coated through charging. This technique provides high directional deposition that is relatively unaffected by a particular width. It provides a good bottom range with high aspect ratios without the use of collimators. Currently designed HCM sputtering targets have a single cup shape. The specific orientation of the permanent magnet is mounted on the outer wall of the target, which generates a high density plasma inside the target zone. This HCM design regenerates the deposited neutrals (ie neutral polar atoms and ions) until they are ionized by high density plasma. Longer target lifetimes are the result of this regeneration effect. Other HCM advantages include longer shield life, extended retention intervals and significantly lower cost of ownership than sputtering techniques. This deposition technique meets the semiconductor industry's needs for sub-0.18 μm devices.

Current techniques for forming HCM targets include machining followed by forging or deep drawing. The billet is hot forged into a cup-shaped target blank using a large amount of extra material. Making the blanks final size requires a large scale machining. Regeneration of the HCM sputter target material is not tolerated by this process. Sputter target replacement requires the manufacture of a new target as a whole.

The extra material consumed for the regeneration of the spent targets, large machining and incompetence are not limited to the HCM targets and are generally a disadvantage of sputter targets. Typically when the corrosion of the target occurs in the form of a groove, the target must be discarded and a new target is produced.

Therefore, there is a need for a more economical and time efficient method for the production of targets including those used in HCM ionizing PVD, and a method for reusing sputter targets containing HCM targets upon corrosion of the target material.

The present invention provides a method for producing and recharging a sputter target for use in physical vapor deposition of thin films. A base shell comprising a hollow cathode magnetron base shell having a size and shape for use in a physical vapor deposition apparatus is coated by thermal spraying technology using a source material that is vapor deposited as a thin film. The source material can be reused upon corrosion of the source material during physical vapor deposition, thus allowing the target source to be produced to be used and reused in the deposition process.

The above and other objects and advantages of the present invention will become more apparent from the detailed description and the accompanying drawings.

1 is a perspective view of a hollow cathode magnetron sputter target;

2 is a cross-sectional view of a hollow cathode magnetron produced by the method of the present invention.

3 is a cross-sectional view of a eroded conventionally shaped sputter target with the original sputter target surface shown in phantom lines.

Explanation of symbols on the main parts of the drawings

10, 20: sputter target 12, 22: base shell

14, 24: source material 30: corrosion surface

The present invention employs a thermal spraying technique for producing sputter targets for use in PVD devices including hollow cathode magnetron sputter targets for use in HCM ionizing PVD devices. The present invention can be used to produce new sputter targets by thermal spray coating of the base shell or can be used to refill the targets consumed by the thermal spray coating on the targets in the corroded portion of the target.

1 shows a hollow cathode magnetron sputter target 10 having a basic cup-shaped structure comprising a base shell 12 and a coating of the source material 14. 2 shows a cross-sectional view of a hollow cathode magnetron base shell 12 with a thermal spray coating of source material 14 in accordance with the principles of the present invention. 3 shows a planar sputter target 20 of a conventional shape having a base shell 22 and a thermal spray coating of the target source material 24 thereon. 3 also illustrates a typical grooved corrosion surface 30 on the target surface where source material 24 is removed from the target surface, ionized, and deposited on a substrate (not shown) during deposition. Such corroded source material may be refilled by thermal spraying techniques in accordance with the principles of the present invention. Rather than producing a new target, the corroded target surface 30 is thermally sprayed to replace the corroded material.

The thermal spray coatings 14, 24 are made from wire or powder material that melts into droplets and are propagated onto the base shells 12, 20 or onto the corroded surface 30 of the target being consumed. Upon impact, droplets from small plates adhering to the surface produce a dense coating on the substrate structure without modification. Thermal spraying techniques useful in the present invention include plasma spraying, flame spraying, high velocity oxy fuel injection, and electric arc spraying. Low pressure plasma injection (LPPS), also known as vacuum plasma injection (VPS), is a plasma injection technique that is guided into a vacuum chamber that is emptied to 10 Torr or less. Plasma spraying is accomplished using heat transferred from the high-kW electric arc to the plasma-forming gas passing through the flow enhancing nozzle. The plasma gun includes a copper electrode and a tungsten electrode, both of which are water cooled. Inside the injection apparatus, the gas flow chamber includes an axial rod cathode adjacent to the nozzle that forms a ring anode. Plasma gas, which is argon, nitrogen, hydrogen, or helium, flows around the cathode through an anode formed as a shrinking nozzle. Plasma is initiated by a conductive path of a direct current arc and a high pressure discharge which forms local ionization between the cathode and the anode. Resistance heating from the arc leads to extreme temperatures of 10,000 ° F. or higher that dissociate and ionize the gas. The plasma exits the anode nozzle as a free or neutral plasma flame. That is, the plasma does not carry current. The powder is transported into the plasma flame through an external powder hole mounted near the anode nozzle outlet. The powder melts into the hot gas and is driven at high speed to the sputtering target surface. Electrical bias is not imposed between the target surface and the nozzle. The high speed flame column produces a dense coating by pushing molten metal droplets onto the substrate at a rate in excess of Mach 2. This process is dust-free and environmentally clean due to the processes contained within the vacuum chamber. This vacuum environment allows the powder to be reused. LPPS typically provides a dense, pore-free coating with a theoretical density of 99%. The coating is also an oxygen free coating and is of high purity.

Preheating the base shells 12, 22 to a high temperature further forms a coating of the source material 14, 24 having a low thermal stress allowing for a thick coating. Cleaning the base shells 12, 22 before coating also constitutes a clean, metallurgical bond that is oxygen free between the coating and the substrate. Thus, LPPS is partially suitable for the present invention due to the high purity of the coating, low oxidizing contaminants, high adhesive strength and high density properties.

Coatings of the target source materials 14 and 24 are metals, metal oxides, metal silicides or alloys deposited on semiconductor wafers, and are preferably high purity materials having a purity of 99% to 99.99999%. Such materials are, for example, pure metals of tantalum, titanium, tungsten, copper, nickel, chromium, aluminum, cobalt, molybdenum, silver, gold, platinum, ruthenium, rhodium, palladium and vanadium, their alloys, their silicides, and their Oxides. Preferred silicides include tantalum, titanium, tungsten, nickel, chromium, cobalt, molybdenum and platinum. For example, a conventionally shaped base shell 22 or HCM base shell 12 is coated with tantalum, titanium, tungsten, copper or aluminum for the deposition of thin films of Ta, TaN, Ti, TiN, W, AlCu and Cu. Can be. Such sputter targets 10 and 20 can be used in applications such as the deposition of Ti / TiN liner / barrier layers of tungsten plugs and aluminum fillers as well as advanced Ta (N) / Cu barrier / seed processes of copper connections. The base shells 12, 22 may be the same material as the coating of the source material 14, 24 or may be a high thermal conductive material such as copper. Coatings using the same material as the base shell are good because they have the same coefficient of thermal expansion as the base shell, thus ensuring the integrity of the target. Optionally, the adhesion effect is achieved by using different materials for the coating and base shell in which the coating material has a lower modulus.

Base shells 12 and 22 may be cast structures cast by any known casting technique or molds such as graphite molds that may be removed when the coating is sprayed. Typically, the base shell has a thickness greater than about 0.125 inches (0.3175 cm). The coating of source material 14, 24 has a thickness of at least about 0.635 cm (0.25 in), preferably greater than about 0.9525 cm (0.375 in), and is deposited on the base shell. In the position where the mold is used as the base shell, the mold is removed leaving only the coating as a target. Targets 10, 20, on the other hand, include a coating of base shells 12, 22 and source material 14, 24.

During the deposition process, the target source materials 14 and 24 are removed from the inner surface of the sputtering target as shown by the corrosion surface 30 in FIG. 3 for the target of conventional shape. In addition, a corrosion surface (not shown) is formed on the inner surface of the HCM sputter target 10 during deposition.

After the sputter target has been sputtered to life (ie, the source material is substantially depleted), the targets 10, 20 are recharged by recharging the target source material using thermal spraying techniques. The inner surface of the target must be recoated in areas where corrosion of the target material occurs. Refilling techniques are useful for targets made by the techniques of the present invention or any other technique. Typically other known techniques typically do not include the use of a base shell. The recharged target includes an inner layer 24 and an outer layer 26, with a corrosion surface 30 constituting a shared surface therebetween.

Sputtering all passageways through the target, ie, sputtering holes through the target, is undesirable. Therefore, before the target is sputtered, the target must be recharged by the technique of the present invention. For example, for a 1/2 inch thick target, the end of the target life is about 0.3175 cm (1/8 inch). In other words, when the target is corroded in any portion below 1/8 inch thick, the target must be recharged by the method of the present invention to recharge the sputter target for continued use. Also, for a target of 0.635 cm (1/4 inch), for example, the target should be recharged at a thickness of about 0.159 cm (1/16 inch).

Thus, the target base shell is regenerated for multiple use by the techniques of the present invention. The recoated target is fully refilled after machining to final size. This refilling technology significantly reduces costs, allowing multiple uses of the shell material of the sputtered targets consumed, and replacing them in simple processing steps to recharge the target, including thermal spraying and machining of the inner surface to the final size. It reduces the amount of material for the production of the target and reduces the manufacturing cycle time.

The present invention has been described by the detailed description of the embodiments, which have been described in great detail, but are not limited to the claims. Additional advantages and modifications will be apparent to those skilled in the art. Therefore, in a broader aspect the invention is not limited to the specific description of the representative apparatus and methods and embodiments shown and described. Thus, new techniques may be made from the above description without departing from the spirit or scope of Applicants' general inventive concepts.

The present invention provides a method for producing and recharging a sputter target for use in physical vapor deposition of thin films. A base shell comprising a hollow cathode magnetron base shell having a size and shape for use in a physical vapor deposition apparatus is coated by thermal spraying technology using a source material that is vapor deposited as a thin film. The source material can be reused upon corrosion of the source material during physical vapor deposition, thus allowing the target source to be produced to be used and reused in the deposition process.

Claims (30)

In the method for producing a sputter target for use in thin film deposition, Providing a target base shell having a size and shape for use in a physical vapor deposition apparatus; Applying a coating formed of a source material of thin film deposition to the target base shell to form a sputter target, The coating portion is a sputter target manufacturing method for use in thin film deposition applied by thermal spraying technology. The group of claim 1, wherein the coating part comprises tantalum, tungsten, copper, nickel, chromium, aluminum, cobalt, molybdenum, silver, gold, platinum, ruthenium, rhodium, palladium, vanadium, oxides thereof, alloys thereof and silicides thereof. A sputter target manufacturing method for use in thin film deposition comprising a material selected from. The method of claim 2, wherein the coating material has a purity of about 99% to about 99.99999%. 3. The method of claim 2, wherein the coating portion is used for thin film deposition made of the same material as the target base shell. 2. The method of claim 1, wherein said coating is applied by a thermal spraying technique selected from the group consisting of plasma spraying, flame spraying, fast oxygen fuel spraying, and electric arc spraying. The method of claim 4, wherein the coating part is used for thin film deposition applied by low pressure plasma spraying. The method of claim 1, further comprising thermally spraying the corroded sputter target with the source material to replace the corroded source material, thereby recharging the sputter target after corrosion using the target in sputter deposition. Sputter target manufacturing method for use in thin film deposition. The method of claim 1, wherein the target base shell is a cup-shaped shell for use in a hollow cathode magnetron physical vapor deposition apparatus. 2. The method of claim 1, wherein said coating is applied to a thin film deposition applied at a thickness of at least about 0.635 cm (0.25 in). 10. The method of claim 9, further comprising recharging the sputter target by thermal spray coating the sputter target using a source material when the coating is corroded to a thickness of at least about 0.15875 cm (0.0625 in). Sputter target manufacturing method for following. 10. The method of claim 9, wherein the target base shell has a thickness of at least about 0.3175 cm (0.125 in). 2. The method of claim 1, wherein said target base shell is a used sputter target having a corroded target surface. A method of making and recharging a sputter target for use and reuse in thin film deposition, Providing a target base shell having a size and shape for use in a physical vapor deposition apparatus; Applying a coating formed of the source material for thin film deposition to the target base shell to form a sputter target, Using a sputter target, the surface material of which the surface is corroded, to deposit a thin film on the substrate; Recharging the corroded sputter target surface by thermal spray coating with the source material to replace the corroded source material, Wherein the coating is a method of manufacturing and refilling the sputter target for use and reuse in thin film deposition applied by thermal spray technology. A method of making and recharging a sputter target for use and reuse in thin film deposition, Providing a target base shell having a thickness of at least about 0.3175 cm (0.125 in), Applying a coating formed of a thin film deposition source material having a thickness of at least about 0.635 cm (0.25 in) to the target base shell to form a sputter target; Using a sputter target, the surface material of which the surface is corroded, to deposit a thin film on the substrate; Recharging the sputter target by thermal spray coating using the source material on the corroded sputter target surface when the coating is corroded to a thickness of at least about 0.15875 cm (0.0625 in), Wherein the coating is a method of manufacturing and refilling the sputter target for use and reuse in thin film deposition applied by thermal spray technology. 15. The method of claim 14, wherein the target base shell is tantalum, tungsten, copper, nickel, chromium, aluminum, cobalt, molybdenum, silver, gold, platinum, ruthenium, rhodium, palladium, vanadium, oxides thereof, alloys thereof and silicides thereof. A method of making and recharging a sputter target for use and reuse in thin film deposition comprising a material selected from the group consisting of: 16. The method of claim 15, wherein the coating portion is the same material as the material of the target base shell. 15. The group of claim 14, wherein the coating portion comprises tantalum, tungsten, copper, nickel, chromium, aluminum, cobalt, molybdenum, silver, gold, platinum, ruthenium, rhodium, palladium, vanadium, oxides thereof, alloys thereof and silicides thereof. A method of making and recharging a sputter target for use and reuse in thin film deposition comprising a material selected from. 18. The method of claim 17, wherein the coating material is used and reused for thin film deposition having a purity of about 99% to about 99.99999%. 15. The method of claim 14, wherein the coating comprises: fabrication of a sputter target for use and reuse in thin film deposition applied by a thermal spraying technique selected from the group consisting of plasma spraying, flame spraying, fast oxygen fuel spraying, and electric arc spraying; Recharging method. 20. The method of claim 19, wherein the coating is for use and reuse in thin film deposition applied by low pressure plasma spray. 15. The method of claim 14, wherein the target base shell is a cup-shaped shell for use in a hollow cathode magnetron physical vapor deposition apparatus. A method of refilling a used sputter target, comprising thermal spraying coating the corrosion surface of the sputter target used to replace the corroded source material using the source material. A target base shell having a sputter source material support surface, A sputter deposition target comprising a sputter source material applied to the support surface by thermal spraying technology. 24. The sputter deposition target of claim 23, wherein the shell is cup-shaped. 24. The sputter deposition target of claim 23, wherein the shell has a thickness of at least about 0.3175 cm (0.125 in). 24. The sputter deposition target of claim 23, wherein the sputter source material has a thickness of about 0.635 cm (0.25 in). The method of claim 23, wherein the sputter source material is tantalum, tungsten, copper, nickel, chromium, aluminum, cobalt, molybdenum, silver, gold, platinum, ruthenium, rhodium, palladium, vanadium, oxides thereof, alloys thereof and silicides thereof. A sputter deposition target comprising a material selected from the group consisting of. 28. The sputter deposition target of claim 27, wherein the sputter source material has a purity of about 99.99999%. The method of claim 21, wherein the sputter source material, An inner layer having an inner surface which is thermally sprayed onto the support surface and which contacts the support surface and which is corroded as a result of sputtering, A sputter deposition target comprising an outer layer thermally sprayed onto the corroded outer surface of the inner layer. 30. The sputter deposition target of claim 29, wherein the internal corrosion layer has a thickness of at least about 0.3175 cm (0.125 in).