Method and apparatus for processing substrate

Abstract

Methods and apparatus for processing a substrate are provided. In some embodiments, a method for processing a substrate includes energizing a target disposed at a distance from a plurality of magnets disposed in a processing volume of a processing chamber; and moving the plurality of magnets away from or close to the target by a predetermined distance based on an anti-target voltage curve determined using a third order polynomial.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to methods and apparatus for processing substrates, and more particularly to methods and apparatus for physical vapor deposition. Background Art

[0002] The inventors have observed that target voltage drift in physical vapor deposition (PVD) chambers, associated with target lifetime (e.g., target erosion), can adversely affect several process parameters, such as the deposition rate or properties of the deposited film on the substrate. The inventors have further observed that known compensation methods, for example, to maintain a constant deposition rate, are inadequate because such methods are highly dependent on target quality and performance consistency. The inventors believe that conventional compensation methods are inadequate for controlling deposition rate. Furthermore, attempts to control deposition rate may not be effective in controlling other parameters affected by target voltage drift.

[0003] Thus, the inventors provide an improved method of controlling target voltage in a PVD process. Summary of the invention

[0004] Methods and apparatus for processing a substrate are provided herein. In some embodiments, the method for processing a substrate includes: energizing a target disposed at a distance from a plurality of magnets disposed in a processing volume of a processing chamber; and moving the plurality of magnets a predetermined distance away from or closer to the target based on an inverse target voltage curve determined using a third-order polynomial.

[0005] In some embodiments, a physical vapor deposition (PVD) processing chamber includes a target disposed in a processing volume of the processing chamber; a plurality of magnets configured to generate a magnetic field in the plasma processing chamber; a power supply configured to supply power to the processing chamber during operation; and a controller. The controller is configured to: energize the target during operation; and move the plurality of magnets a predetermined distance away from or closer to the target based on an inverse target voltage curve determined using a third-order polynomial.

[0006] Other embodiments and further embodiments of the present invention are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] While the above briefly summarizes embodiments of the present invention, embodiments of the present invention will be discussed in more detail below. Such embodiments may be understood by reference to the accompanying drawings, which depict illustrative embodiments of the present invention. However, the drawings illustrate only typical embodiments of the present invention and are therefore not to be considered limiting of the scope of the present invention, as the present invention admits to other equally effective embodiments.

[0008] Figure 1 Depicted is a cross-sectional view of a processing chamber in accordance with at least some embodiments of the present disclosure.

[0009] Figure 2 is a flowchart of a method for processing a substrate according to at least some embodiments of the present case.

[0010] Figure 3 is a graph of the relationship between target voltage and magnet spacing and target life in kilowatt-hours (kWh) according to at least some embodiments of the present case.

[0011] For ease of understanding, the same reference numerals have been used to denote common identical elements in the figures wherever possible. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated into other embodiments without further recitation. Detailed Embodiments

[0012] Embodiments of methods and apparatuses for processing substrates are provided herein. By way of example, the methods and apparatuses described herein are configured to maintain a substantially constant target voltage during processing. By way of example, the method may include: energizing a target disposed at a first distance from a plurality of magnets in a processing volume disposed in a processing chamber. During processing, the method may include moving the plurality of magnets a predetermined distance away from or towards the target based on a predetermined magnetic lift compensation factor determined using two or more third-order polynomials. Different from the known compensation methods described above that highly depend on target quality and / or target performance consistency, the methods and apparatuses described herein maintain a substantially constant target voltage without changing the recipe time and / or making power adjustments to the target. In addition, the methods and apparatuses described herein can advantageously increase the expected operable target life from about 1200 kWh to about 2000 kWh.

[0013] Figure 1 Depicts a cross-sectional view of a PVD processing chamber (processing chamber 100) according to some embodiments of the present case. Examples of suitable PVD chambers are available from Applied Materials, Inc. of Santa Clara, California. Other processing chambers from Applied Materials, Inc. or other manufacturers may also benefit from the inventive apparatus disclosed herein.

[0014] The processing chamber 100 includes a substrate support 102 for receiving a substrate 104 thereon, and a sputtering source (such as a target 106). The substrate support 102 may be located within a wall 108 (such as a ground shield), which may be a chamber wall (as shown) or a ground shield.

[0015] The processing chamber 100 includes one or more feed structures for coupling RF and / or DC energy to the target 106. The target 106 may be coupled to an RF power supply 118 and / or a DC power supply 120, and the RF power supply 118 and / or the DC power supply 120 may be used independently or jointly to supply RF and / or DC energy to the target 106, respectively. For example, the DC power supply 120 may be used to apply a negative voltage or bias voltage to the target 106. In some embodiments, multiple (i.e., two or more) RF power supplies may be provided to supply RF energy at multiple frequencies.

[0016] In some embodiments, the RF power supply 118 and / or the DC power supply 120 may be coupled to a source distribution plate 122. The source distribution plate 122 includes holes 124 formed therethrough to facilitate the passage of the rotation axis 170 of the rotatable magnetron assembly 136 as will be discussed in more detail below. The source distribution plate 122 may be made of a suitable conductive material to conduct RF and DC energy from the RF power supply 118 and / or the DC power supply 120. The source distribution plate 122 may be coupled to the target 106 through a conductive member 125. The conductive member 125 may be a tubular member having a first end 126 that is coupled to the target-facing surface 128 of the source distribution plate 122 near the periphery of the source distribution plate 122. The conductive member 125 further includes a second end 130 that is coupled to the source-facing surface 132 of the target 106 (or coupled to the backplate 146 of the target 106) near the periphery of the target 106.

[0017] The illustrated ground shield 140 covers Figure 1 at least some of the portions above the target 106 in the processing chamber 100. In some embodiments, the ground shield 140 may extend below the target 106, thereby also surrounding the substrate support 102. The ground shield 140 may be arranged to cover the outer surface of the lid of the processing chamber 100. The ground shield 140 may be coupled to ground, for example, through a ground connection of the body of the processing chamber 100. The ground shield 140 has a central opening to allow the rotation axis 170 to pass through the ground shield 140. The ground shield 140 includes additional openings to route the feed structures therethrough without electrical contact with the ground shield 140 (e.g., for RF and / or DC power supplies). The ground shield 140 may comprise any suitable conductive material such as aluminum, copper, or the like.

[0018] An insulating gap 139 is provided between the ground shield 140 and the outer surfaces of the source distribution plate 122, the conductive member 125, and the target 106 (and / or the backplate 146) to prevent RF and DC energy from directly reaching the ground. The insulating gap 139 may be filled with air or some other suitable dielectric material, such as ceramic, plastic, or the like.

[0019] A separator plate 138 may be provided between the source distribution plate 122 and the ground shield 140 to prevent RF and DC energy from directly leading to the ground. The separator plate 138 has a central opening to allow the rotation shaft 170 to pass therethrough. The separator plate 138 includes additional openings to allow routing of the feed structure to pass therethrough (such as for RF and / or DC power supplies). The separator plate 138 may comprise a suitable dielectric material, such as ceramic, plastic or the like. Alternatively, an air gap may be provided to replace the separator plate 138. In embodiments where an air gap is provided to replace the separator plate, the structure of the ground shield 140 is strong enough to support any components resting on the ground shield 140.

[0020] The inner wall of the conductive member 125, the target-facing surface 128 of the source distribution plate 122, and the source-distribution-plate-facing surface 132 of the target 106 may define a cavity 134. The cavity 134 may be utilized to at least partially accommodate one or more parts of the rotatable magnetron assembly 136, as Figure 1 shown. In some embodiments, the cavity may be at least partially filled with a cooling fluid, such as water (H2O) or the like.

[0021] The target 106 may be supported on an adapter 142 (such as a grounded conductive aluminum adapter) by a dielectric isolator 144. The target 106 contains the material to be deposited on the substrate 104 during sputtering, such as a metal (or metal oxide), such as copper, tantalum, titanium or the like. For example, in at least some embodiments, the target 106 may be made of tantalum.

[0022] The backplate 146 may be coupled to the target-facing surface 132 of the target 106. The backplate 146 may comprise a conductive material, such as copper zinc, copper chromium or the same material as the target, such that the RF and DC power supplies may be coupled to the target 106 through the backplate 146. Alternatively, the backplate 146 may be non-conductive and may comprise conductive elements (not shown), such as electrical feedthroughs or the like, for coupling the target-facing surface 132 of the target 106 to the second end 130 of the conductive member 125. The backplate 146 may be included (for example) to improve the structural stability of the target 106.

[0023] The rotatable magnetron assembly 136 can be positioned near the back surface of the target 106 (e.g., the surface 132 facing the source distribution plate). The rotatable magnetron assembly 136 includes a plurality of magnets 166 supported by a bottom plate 168. The bottom plate 168 is connected to a rotation axis 170 that coincides with the central axis of the processing chamber 100, the target 106, and the substrate 104. The plurality of magnets 166 can be configured in fixed positions relative to the rotation axis 170, or can have one or more adjustable positions relative to the rotation axis 170. For example, in some embodiments, a two-position magnetron can be provided that has an internal position (e.g., radially internal relative to the rotation axis 170) for the plurality of magnets 166 and an external position (e.g., radially external relative to the rotation axis 170) for the plurality of magnets 166.

[0024] The motion controller 172 can be coupled to the upper end of the rotation axis 170 to drive the rotation of the magnetron assembly 136. The motion controller 172, or a different motion controller, can be used to control the relative position of the plurality of magnets 166 of the rotatable magnetron assembly 136 relative to the target 106 (e.g., control the distance between the plurality of magnets 166 and the target 106). The motion controller can include one or more of a motor, a rotary actuator, a linear actuator, or the like. The plurality of magnets 166 generate a magnetic field within the processing chamber 100 that is generally parallel to and close to the surface of the target 106 for capturing electrons and increasing the local plasma density, thereby increasing the sputtering rate. The plurality of magnets 166 generate an electromagnetic field near the top of the processing chamber 100, and rotate the plurality of magnets 166 to rotate the electromagnetic field, thereby more uniformly affecting the plasma density of the process of sputtering the target 106. For example, the rotation axis 170 can make about 0 to about 150 rotations per minute.

[0025] In some embodiments, the motion controller 172 is configured to control the rotation of the magnetron assembly 136, and a separate lift mechanism 171 is coupled to the rotation axis 170 and is configured to selectively raise or lower the plurality of magnets 166 of the magnetron assembly 136 relative to the back surface of the target 106 (e.g., control the distance). U.S. Patent No. 7,674,360, titled "Mechanism for Varying The Spacing Between Sputter Magnetron And Target" and commonly owned, discloses such a lift mechanism.

[0026] In some embodiments, a magnet 190 can be provided near the processing chamber 100 for selectively providing a magnetic field between the substrate support 102 and the target 106. For example, as Figure 1As shown, at the processing position, a magnet 190 can be disposed in the region outside the wall 108 and exactly above the substrate support 102. In some embodiments, the magnet 190 can be alternatively or additionally disposed at other positions, such as adjacent to the adapter 142. The magnet 190 can be an electromagnet and can be coupled to a power source (not shown) to control the magnetic field generated by the electromagnet.

[0027] The substrate support 102 has a material receiving surface facing the main surface of the target 106 and supports the substrate 104 that will be sputter-coated at a planar position opposite to the main surface of the target 106. The substrate support 102 can support the substrate 104 in the central region 148 of the processing chamber 100. The central region 148 is defined as the region above the substrate support 102 during processing (e.g., between the target 106 and the substrate support 102 at the processing position).

[0028] In some embodiments, the substrate support 102 can be vertically moved through the bellows 150 connected to the bottom chamber wall 152, allowing the substrate 104 to be transferred onto the substrate support 102 through a load lock valve (not shown) at the lower part of the processing chamber 100 and then raised to the deposition or processing position.

[0029] One or more processing gases can be supplied to the lower part of the processing chamber 100 from the gas source 154 through the mass flow controller 156. An exhaust port 158 can be provided and is coupled to a pump (not shown) through a valve 160 for evacuating the inside of the processing chamber 100 and facilitating the maintenance of the desired pressure inside the processing chamber 100.

[0030] The RF bias power supply 162 can be coupled (e.g., through a matching circuit) to the substrate support 102 to induce a negative DC bias on the substrate 104. Additionally, in some embodiments, a negative DC self-bias may be formed on the substrate 104 during processing. For example, the frequency range of the RF power provided by the RF bias power supply 162 can be from about 2 MHz to about 60 MHz. Non-limiting frequencies are, for example, 2 MHz, 13.56 MHz, or 60 MHz. In other applications, the substrate support 102 can be grounded or electrically floating. In some embodiments, a capacitance tuner 164 can be coupled to the substrate support base to adjust the voltage on the substrate 104 in applications where the RF power supply is coupled to the target and an RF bias power supply is not required.

[0031] In some embodiments, the processing chamber 100 may further include a grounded bottom shield 174 connected to the protrusion 176 of the adapter 142. The dark zone shield 178 may be supported on the bottom shield 174 and may be fastened to the bottom shield 174 by screws or other suitable means. The metal threaded connection between the bottom shield 174 and the dark zone shield 178 allows the bottom shield 174 and the dark zone shield 178 to be grounded to the adapter 142. The adapter 142 is in turn sealed and grounded to the wall 108. The bottom shield 174 and the dark zone shield 178 are typically both formed of a non-magnetic hard metal such as stainless steel or aluminum.

[0032] The bottom shield 174 extends downward and may include a generally tubular portion 180 having a generally constant diameter. The bottom shield 174 extends downward along the wall of the adapter 142 and the wall 108 below the top surface of the substrate support 102 and then returns upward until it reaches the top surface of the substrate support 102 (e.g., forming a U-shaped portion 184 at the bottom). The cover ring 186 rests against the upwardly extending interior 188 of the bottom shield 174 when the substrate support 102 is in the lower loading position, but against the outer periphery of the substrate support 102 when the substrate support 102 is in the upper deposition position, thereby protecting the substrate support 102 from sputter deposition. An additional deposition ring (not shown) may be used to protect the outer periphery of the substrate 104 from deposition.

[0033] In some embodiments, the processing chamber 100 may include an inductive coil 143 (e.g., for an inductively coupled plasma process). The inductive coil 143 may have one or more turns. The inductive coil 143 may be located exactly within the bottom shield 174 and above the substrate support 102. The inductive coil 143 may be positioned closer to the substrate support 102 than the target 106. The inductive coil 143 may be formed of a material similar in composition (such as tantalum or niobium) to the target 106 to serve as a secondary sputtering target. The inductive coil 143 is supported by the bottom shield 174 by a plurality of coil spacers 145. The coil spacers 145 may electrically isolate the inductive coil 143 from the bottom shield 174 and other chamber components.

[0034] The inductive coil 143 may be coupled to a power supply 147. The power supply 147 may have electrical leads extending through the wall 108, the bottom shield 174, and the coil spacer 145. The electrical leads may be connected to a lug 149 on the inductive coil 143 to provide power to the inductive coil 143. The lug 149 may have a plurality of insulated electrical connections for providing power to the inductive coil 143. Additionally, the lug 149 may be configured to connect to the coil spacer 145 and support the inductive coil 143. In embodiments, the power supply 147 applies current to the inductive coil 143 to induce an RF field in the processing chamber 100 and couple power into the plasma, thereby increasing the plasma density, such as the concentration of reactant ions. In some embodiments, the inductive coil 143 operates at an RF power frequency that is lower than the RF power frequency of the RF power supply 118. In one embodiment, the RF power supplied to the inductive coil 143 has a frequency of approximately 2 MHz. In other embodiments, the RF power frequency may operate in the range of approximately 1.8 MHz to approximately 2.2 MHz. In other embodiments, the RF power frequency may be in the range of approximately 0.1 MHz to approximately 99 MHz. In some embodiments, the inductor coil 143 is made of a material that can be sputtered onto a substrate, such as a metal. The power supply 147 may then also apply DC power to the inductor coil 143, thereby enabling sputtering of the inductor coil 143 while simultaneously coupling RF power to the plasma.

[0035] The processing chamber 100 includes a system controller 113 to control the operation of the processing chamber 100 during processing. The system controller 113 includes a central processing unit (CPU) 117, memory 119 (e.g., a non-transitory computer-readable storage medium), and support circuits 123 for the CPU 117 to facilitate control of the components of the processing chamber 100. The system controller 113 can be one of any form of general-purpose computer processor used in industrial environments to control various chambers and sub-processors. The memory 119 stores software instructions (source code or object code) that can be executed or called to control the operation of the processing chamber 100 in the manner described herein. When processing the substrate 104, the processing chamber 100 can use an RF power supply 118, a DC power supply 120, and / or a power supply 147 to sputter metals, such as tantalum or titanium, or derivatives thereof. For example, in some embodiments, the DC power supply 120 is operated to generate DC power to sputter the metal target when the power supply 147 is used as a DC source to sputter the inductive coil 143, and is used as an RF power source at a frequency lower than the operating RF frequency of the RF bias power supply 162 to increase the plasma density in the central region 148. In some embodiments, the power supply 147 operates at an RF power frequency of about 0.1 MHz to 99 MHz. In other embodiments, the power supply 147 operates at an RF power frequency of about 1.8 MHz to about 2.2 MHz.

[0036] In some embodiments, the target 106 and the inductive coil 143 are made of the same material such as tantalum or titanium. The dual sources help to provide a stable plasma and sufficient energy to selectively etch, for example, one or more process gases (such as at least one of argon, nitrogen, or one or more other inert gases), while keeping the metal film intact or at least etching minimally. The RF bias power supply 162 operates at an RF power frequency greater than the operating RF power frequency of the power supply 147 to bias the substrate 104. In some embodiments, the RF bias power supply 162 operates at an RF power frequency of about 1 MHz to about 100 MHz. In other embodiments, the RF bias power supply 162 operates at an RF power frequency of about 13.56 MHz.

[0037] Figure 2 is a flowchart of a method 200 (such as a closed-loop feedback system) for processing a substrate according to at least some embodiments of the present case. For example, the method 200 uses a control algorithm to ensure that a substantially constant target voltage is maintained at the target. For illustrative purposes, a new target (such as from the start of the target life) is used when describing the method 200.

[0038] In at least some embodiments, the method 200 can be used for high DC power deposition processes. During such processes, the target voltage affects film properties, deposition rates, and the like. Thus, the method 200 can be used to maintain a substantially constant target voltage by adjusting the distance of the magnet (such as the plurality of magnets 166) relative to the target, thereby maintaining component yield, such as maintaining the same film properties throughout the target life. For example, with respect to a PVD process (such as a TaN PVD process), a high target voltage provides a high sputtering yield and high ion energy, which affects deposition rate, adhesion, density, resistivity, and the like.

[0039] Similarly, the method 200 can be used for low DC power processing deposition processes, such as the dynamic processing of ALD TaN, where the inductive coil 143 voltage affects film properties, such as deposition rate and non-uniformity. The inventors have found that due to the coupling between the target and the coil plasma, the coil voltage can be modulated by the target voltage. Thus, the method 200 can maintain a substantially constant target voltage by adjusting the distance of the magnet relative to the target, for example, the coil voltage can be adjusted and compensated throughout the target and coil life.

[0040] For example, the inventors have discovered that a control algorithm using a high-order polynomial has higher performance in tracking the erosion rate of the target material. Such a high-order polynomial can be configured to compensate for relatively small erosion of the target material and has more consistent performance than a control algorithm using a linear function. In at least some embodiments, the high-order polynomial can be a second-order or higher-order polynomial. For example, in at least some embodiments, the high-order polynomial can be a third-order polynomial of the form of equation (1):

[0041] y=c3*(x-x0) 3 + c2*(x-x0) 2 + c1*(x-x0) + c0 (1)

[0042] Where y = target-to-magnet spacing offset, x = target age in kWh, x0 = starting target age in kWh (e.g., after wear), and c0 = magnet lift position offset from the initial target spacing set point when target life is zero (e.g., 0 kWh). In the above example, between the front surface of the plurality of magnets and the facing surface of the target assembly (e.g., Figure 1 The spacing or distance between the target and the plurality of magnets is measured between the top surface of the backing plate 146 shown in FIG. However, other reference points can be used to define the distance between the plurality of magnets and the target assembly, and the distance can be adjusted accordingly. In some embodiments, the above equations can be used to rotate a magnetron with the plurality of magnets at a fixed radial position relative to the axis of rotation. In some embodiments, the above equations can be used to rotate a magnetron with the plurality of magnets at at least two fixed radial positions (e.g., at least an inner radial position and an outer radial position) relative to the axis of rotation.

[0043] For example, when starting a process with a new target, an initial distance between the plurality of magnets and the target (e.g., an initial spacing setpoint) can be set to provide a desired target voltage given the target material and the process conditions to be performed. In some embodiments, the initial spacing setpoint can be, for example, approximately 1.25 mm, although other distances can be used depending on the process chamber configuration. After the new target is worn away, the above equation can be used to determine the spacing between the plurality of magnets and the target by adding the calculated y value to the initial spacing setpoint (e.g., y can be calculated for a target lifetime x = x0). After processing substrates over time, the above equation can be used to determine the spacing between the plurality of magnets and the target as the target lifetime progresses (e.g., by calculating y over the target lifetime and adding the calculated y value to the initial spacing setpoint).

[0044] In at least some embodiments, a third-order polynomial uses coefficients (such as constants) specific to a corresponding target. That is, the constant coefficients for a particular target are configured to provide an inverse curve of the corresponding voltage curve. Once the coefficients are calculated for a particular target, the control algorithm uses the coefficients to determine the magnetic lift compensation factor for that particular target. For example, coefficients c1 to c3 can be used to represent the erosion rate of the corresponding target. For example, through empirical data, the inventors obtained target voltage curves specific to the corresponding targets (such as tantalum, titanium, etc.) and indicating the previous empirical performance of the corresponding targets (e.g., Figure 3 as shown, the target voltage versus the target life in kilowatt-hours (kWh)). For example, the inventors found that at the start of the target life, the target voltage will begin to decrease during substrate processing ( Figure 3 triangle data from points 1 to 2 on the graph of Figure 3 ), and based on the particular target, the target voltage will reach the bottom inflection point ( Figure 3 triangle data point 3 on the graph of

[0045] while the substrate processing continues, and will begin to increase as the substrate processing continues ( Figure 3 triangle data from points 4 to 5 on the graph of

[0045] ). For example, for at least some tantalum targets, at the start of the target life (such as 0 kWh), the target voltage provided at the target can be about 610 volts. As the target is used, the target voltage at the target will begin to decrease (e.g., decrease to about 500 volts) and reach the bottom inflection point at about 1000 kWh. Then, the target voltage at the target will begin to increase to about 600 volts at about 1800 kWh. The above process can be used to determine coefficients c1 to c3 for other processes, such as processes using different target materials, different chamber configurations, or the like.

[0046] Then, at 204, the method includes moving a plurality of magnets away from or closer to the target based on a predetermined inverse voltage curve trajectory (e.g., the inverse of the target voltage curve) determined using (e.g.) the third-order polynomial described above. For example, the inventors obtained an open-loop control algorithm, such as the magnet position as a function of kWh of the corresponding target, which is configured to determine the target voltage curve using an inverse voltage curve trajectory determined based on a third-order polynomial. For each corresponding target, the open-loop control algorithm is configured to obtain a linear voltage response for the corresponding target life (such as kWh), thereby providing repeatability between targets. For example, the methods and apparatuses described herein enable a user to achieve desired processing results by adjusting the magnet-to-target spacing as a function of kilowatt-hours to maintain a substantially constant voltage (e.g., within about 1% to about 3% of a predetermined voltage, and in some embodiments 0.75% to about 1.5%) during the target life. For different target materials, process chamber configurations, and / or processing conditions, the initial third-order polynomial can be calculated empirically during a test run of (e.g.) one or more targets.

[0047] Thus, since method 200 uses a new target (e.g., the target voltage will decrease as the target corrodes), the controller moves the plurality of magnets away from (or towards) the target a predetermined distance based on the previously determined inverse voltage curve trajectory ( Figure 3 the rectangular data from point 1 to point 2 in the graph of). The controller continues to move the plurality of magnets away from the target a predetermined distance until the target voltage reaches the stagnation point of the voltage curve of that target (such as Figure 3 the top inflection rectangular data point 6 on the graph of). Then, for continued substrate processing, the inverse voltage curve begins to decline as substrate processing continues ( Figure 3 the rectangular data from point 4 to point 5 in the graph of), and the controller begins to move the plurality of magnets towards the target a predetermined distance until the inverse voltage curve trajectory ( Figure 3 the rectangular data on the graph of) and the voltage target curve (e.g., Figure 3 the triangular graph of) intersect (not shown), at which point the target can be replaced. In at least some embodiments, such as when using different targets, the trajectory curve and / or higher-order polynomial can be adjusted to accommodate different targets. The calculation and adjustment of the magnet-to-target spacing can be performed at any time (such as continuously) after processing each substrate or after a set amount of time or after processing a set number of substrates.

[0048] As noted above, moving a plurality of magnets to maintain a substantially constant target voltage can have several advantages, including: 1) controlling the particle energy and thus controlling the sputtering yield, which directly affects processing parameters such as deposition rate, adhesion, density, and resistivity; and 2) controlling the coil voltage to provide a higher film deposition rate and uniformity.

[0049] During the operational life of the target, the target can be advantageously maintained at a substantially constant voltage (e.g., within about 1% to about 3%, and in some embodiments, about 0.75% to about 1.5% of a nominal target voltage) by raising or lowering the plurality of magnets. The nominal target voltage can be a predetermined target voltage, an average target voltage, or a target voltage determined by processing substrates using a particular process recipe or the like.

[0050] Furthermore, in addition to moving the target, one or more other processing chamber parameters may also be adjusted / modified. For example, before or after 208, one or more adjustments to the power supplied to the target, the flow rate of the process gas, or the radial position of the plurality of magnets may also be performed.

[0051] Although the foregoing is directed to embodiments of the present invention, other embodiments and further embodiments of the present invention may be devised without departing from the basic scope of the present invention.

Claims

1. A method for processing a substrate, the method comprising: Applying power to a target disposed at a distance from a plurality of magnets in a processing volume of a processing chamber; and Moving the plurality of magnets away from or closer to the target by a predetermined distance based on an inverse target voltage curve determined using a third-order polynomial.

2. The method of claim 1, wherein the target is at least one of tantalum or titanium.

3. The method of claim 1, wherein the third-order polynomial uses coefficients specific to the corresponding target.

4. The method of claim 3, wherein the coefficients specific to the corresponding target are based on the corrosion rate of the corresponding target.

5. The method of claim 1, wherein the third-order polynomial is in the following form: y = c3*(x - x0) 3 + c2*(x - x0) 2 + c1*(x - x0) + c0 where y = the spacing offset between the target and the plurality of magnets, x = target kWh, and x0 = starting target kWh.

6. The method of any one of claims 1 to 5, wherein the voltage of the target is maintained at about 1% to about 3% of the nominal target voltage.

7. The method of any one of claims 1 to 5, the method further comprising: adjusting at least one of the power supplied to the target, the gas flow rate of the process gas, or the radial position of the plurality of magnets.

8. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, perform a method for processing a substrate, the method comprising: Applying power to a target disposed at a distance from a plurality of magnets in a processing volume of a processing chamber; and Moving the plurality of magnets away from or closer to the target by a predetermined distance based on an inverse target voltage curve determined using a third-order polynomial.

9. The non-transitory computer-readable storage medium of claim 8, wherein the target is at least one of tantalum or titanium.

10. The non-transitory computer-readable storage medium of claim 8, wherein the third-order polynomial uses coefficients specific to the corresponding target.

11. The non-transitory computer-readable storage medium of claim 10, wherein the coefficients specific to the corresponding target are based on the corrosion rate of the corresponding target.

12. The non-transitory computer-readable storage medium of claim 8, wherein the third-order polynomial is in the following form: y = c3*(x - x0) 3 + c2*(x - x0) 2 + c1*(x - x0) + c0 where y = the spacing offset between the target and the plurality of magnets, x = target kWh, and x0 = starting target kWh.

13. The non-transitory computer-readable storage medium of any one of claims 8 to 12, wherein the voltage of the target is maintained at about 1% to about 3% of the nominal target voltage.

14. The non-transitory computer-readable storage medium of any one of claims 8 to 12, the non-transitory computer-readable storage medium further comprising: adjusting at least one of the power supplied to the target, the gas flow rate of the process gas, or the radial position of the plurality of magnets.

15. A physical vapor deposition (PVD) processing chamber, the PVD processing chamber comprising: A target disposed within a processing volume of the processing chamber; A plurality of magnets configured to generate a magnetic field within the processing chamber; A power supply configured to supply power to the processing chamber during operation; and a controller configured to: energize the target during operation; and move the plurality of magnets away from or closer to the target by a predetermined distance based on an inverse target voltage curve determined using a third-order polynomial.

16. The PVD processing chamber of claim 15, wherein the target is at least one of tantalum or titanium.

17. The PVD processing chamber of claim 15, wherein the third-order polynomial uses coefficients specific to the corresponding target.

18. The PVD processing chamber of claim 17, wherein the coefficients specific to the corresponding target are based on the corrosion rate of the corresponding target.

19. The PVD processing chamber of claim 15, wherein the third-order polynomial is in the form of: y = c3*(x - x0) 3 + c2*(x - x0) 2 + c1*(x - x0) + c0 where y = the spacing offset between the target and the plurality of magnets, x = the target kWh, and x0 = the starting target kWh.

20. The PVD processing chamber of any one of claims 15 to 19, wherein the controller is further configured to maintain the voltage of the target at about 1 percent to about 3 percent of the nominal target voltage during use.

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