Patent Application
20240200223
Electrochemical deposition processing is widely used in the semiconductor industry for metallization of integrated circuit manufacturing. Electrochemical deposition processes deposit metal or metal alloys, such as copper, cobalt, and nickel, for example, into trenches and/or vias that are pre-formed in dielectric layers. In this process, a thin adherent metal diffusion-barrier film is pre-deposited onto the surface using physical vapor deposition (PVD) or chemical vapor deposition (CVD). A thin metal seed layer will then be deposited on top of the barrier layer, typically by a PVD deposition process. The features (vias and trenches) are then filled electrochemically with a metal or metal alloy through an electrochemical deposition process, during which the metal or metal alloy anion is reduced electrochemically to the metal, such as a copper anion being reduced electrochemically to copper metal.
Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. The following, non-limiting implementations are considered part of the disclosure; other implementations will be evident from the entirety of this disclosure and the accompanying drawings as well.
The various implementations disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.
The following terms are used intermittently throughout the instant disclosure:
“Substrate”—In this application, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate” and “partially fabricated integrated circuit” are used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of integrated circuit fabrication thereon. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. Further, the terms “electrolyte,” “electroplating bath,” “plating bath,” “bath,” “electroplating solution,” and “plating solution” are used interchangeably. The work piece may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work pieces that may take advantage of the disclosed embodiments include various articles such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micro-mechanical devices and the like.
“Electroplating cell”—a cell, typically configured to house an anode and a cathode, positioned opposite to each other. Electroplating, which takes place on the cathode in an electroplating cell, refers to a process that uses electric current to reduce dissolved metal cations so that they form a thin coherent metal coating on an electrode. In certain embodiments, an electroplating system has two compartments, one for housing the anode and the other for housing the cathode. In certain embodiments, an anode chamber and a cathode chamber are separated by a semi-permeable membrane that permits for the selective movement of concentrations of ionic species therethrough. The membrane may be an ion exchange membrane such as a cation exchange membrane. For some implementations, versions of Nafion™ (e.g., Nafion 324) are suitable for use as such a membrane.
“Anode chamber”—a chamber within the electroplating cell designed to house an anode. The anode chamber may contain a support for holding an anode and/or providing one or more electrical connections to the anode. The anode chamber may be separated from the cathode chamber by a semi-permeable membrane. The electrolyte held in the anode chamber is sometimes referred to as anolyte.
“Cathode chamber”—a chamber within the electroplating cell designed to house a cathode. Often in the context of this disclosure, the cathode is a substrate such as a wafer, e.g., a silicon wafer, having multiple partially fabricated semiconductor devices. The electrolyte held in the cathode chamber is sometimes referred to as catholyte. In many implementations, the cathode may be removable from the cathode chamber in order to allow a wafer to be connected with the cathode; the cathode may then be reintroduced into the cathode chamber and immersed in the catholyte. It will be understood that the anode chamber and the cathode chamber may also refer to different portions of the same overall structure, e.g., the electroplating cell. If a membrane is used, the membrane may serve as a partition between the two chambers.
“Electroplating solution” (or electroplating bath, plating electrolyte, bath, electroplating solution, solution, or primary electrolyte)—a liquid of dissociated metal ions, often in solution with a conductivity-enhancing solvent such as an acid or base. The dissolved cations and anions disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons.
“Recirculation system”—a system that circulates the electroplating solution back into a central reservoir for subsequent re-use. A recirculation system may be configured to efficiently re-use electroplating solution and also to control and/or maintain concentration levels of metal ions within the solution as desired. A recirculation system may include pipes or other fluidic conduits together with a pump or other mechanism for driving recirculation.
Manufacturing of semiconductor devices commonly requires deposition of electrically conductive material on semiconductor wafers. The conductive material, such as copper, nickel, and cobalt, for instance, is often deposited by electroplating onto a seed layer of metal deposited onto the wafer surface by various methods, such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Electroplating is generally used for depositing metal into the vias and trenches of the processed wafer during Damascene and dual Damascene processing.
Electroplating is typically performed in an electroplating bath, in which the semiconductor wafer is submerged in an electroplating solution. An electroplating solution (or solution, electrolyte solution, electroplating bath, plating electrolyte, or primary electrolyte) may be considered a liquid of dissociated metal ions, often in solution with a conductivity enhancing component such as an acid or base. The dissolved cations and anions disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons.
The composition of electroplating solution is selected so as to optimize the rates and uniformity of electroplating. During some copper plating processes, copper salt serves as the source of the copper cation, and also provides conductivity to the electroplating solution; in certain embodiments, sulfuric acid enhances electroplating solution conductivity by providing hydrogen ions as charge carriers. Also, organic additives, generally known in the art as accelerators, suppressors, or levelers, are capable of selectively enhancing or suppressing rate of copper (Cu) deposition on different surfaces and wafer features, for instance.
Some electroplating solutions use a dissolved gas, such as oxygen or nitrogen, to control the various constituents in the electroplating solution, including the additives as well as byproducts. For example, some copper electroplating processes produce copper one (Cu1+) as a byproduct which can adversely affect the electroplating process and resulting wafer performance. In some implementations, the Cu1+ is a highly reactive species that is the product of anode electrolysis and it reacts with one or more of the organic additives in the plating solution to form a reduced state of the one or more additives. The reduced state of certain organic additives has different reactivity than in the oxidized state which can change the performance of the electroplating solution and resulting electrodeposition. In the presence of the electroplating solution's dissolved gas, however, the presence and effect of the Cu1+ may be controlled. For instance, dissolved oxygen can oxidize the Cu1+ to a stable bath ionic species copper two (Cu2+) via the reaction of 2Cu1++2H++O2/2 which results in 2Cu2++H2O.
Various implementations control the concentration of the dissolved gas in the electroplating solution because too much or too little of the dissolved gas may have detrimental effects. For instance, too much dissolved gas in the electroplating solution may result in forming gas bubbles, such as microbubbles, which can lead to wafer defects. Too much dissolved gas may also, in some implementations, adversely affect other aspects of the electroplating system, such as causing chemical corrosion of a consumable electrode, including a copper anode, for example. On the other hand, too little dissolved gas may not adequately control the target constituent in the electroplating solution. For example, too little dissolved oxygen in the electroplating solution may not reduce the Cu1+ to the desired levels. It is therefore desirable to control the dissolved gas concentration in the electroplating solution at a “sub-saturation” concentration, greater than zero, in the solution. A sub-saturation concentration is a concentration in which additional gas could be dissolved in the solution without generating gas bubbles. In some embodiments, a desired sub-saturation concentration is referred to as an intermediate concentration.
Described herein are methods, techniques, systems, and apparatuses for controlling dissolved gas concentrations in electroplating solutions. A degassing device, such as a contactor, fluidically connected to the electroplating system may be used to control the dissolved gas concentration in the electroplating solution. The pressure within the contactor controls the dissolved gas concentration of the electroplating solution flowed through the contactor and some implementations may therefore control and maintain a desired dissolved gas concentration by controlling the pressure within the contactor. This control may rely on feedback from pressure sensors in the degassing device and/or gas sensors that determine the dissolved gas concentration in the electroplating solution. The contactor pressure may be controlled in some embodiments by selectively applying a vacuum to the contactor and/or by using a pressure regulator. In some embodiments, the dissolved gas concentration may be controlled to account for the different states of the electroplating cells or system, such as whether a wafer is in, or out of, an electroplating cell, and whether electroplating is being performed or the system is at idle, for example.
While some the embodiments described herein concern copper electroplating systems and dissolved oxygen concentration in a copper electroplating solution, the disclosed embodiments are not limited to this system. The concepts generally apply to controlling the concentration of any dissolved gas in an electrolyte for electroplating any metal, where the concentration of dissolved gas has an impact on one or more aspects of the electroplating. The disclosed embodiments are not limited to controlling oxygen as the dissolved gas. The embodiments may extend to other dissolved gases such as nitrogen.
Various mechanisms may be employed to control the dissolved gas concentration to an intermediate or sub-saturation level within the electrolyte.
The various systems and apparatuses described herein are able to control dissolved gas concentrations in electroplating solutions.
The degassing device, including the contactor 108, is configured to remove gas from the liquid flowed within the device. Some implementations of the contactor 108 may have a hydrophobic gas-liquid separation membrane through which gas, not liquid, can flow and by applying a vacuum to one side of the membrane while flowing the liquid on the other side of the membrane, the dissolved gas in the solution is forced through the membrane pores and carried away by the vacuum. The membrane may have hundreds or thousands of hollow fibers to create a large surface area for liquid-gas contact. By flowing liquid on the outside, or “shell side,” of the membrane's hollow fibers, and applying a vacuum to the inside, or “lumen side,” of the membrane's hollow fibers, the gas in the liquid is forced from the shell side to the lumen side through the membrane and drawn out of the contactor by the vacuum.
The vacuum source 110 may be a vacuum pump configured to provide a vacuum, such as a one or two stage mechanical dry pump and/or turbomolecular pump, that can draw gases out of the contactor. The vacuum source 110 may be configured to reduce the pressure in the contactor between, for example, 0 and 2 Atm, including between 0.1 Atm and 1 Atm. The vacuum source may also be a vacuum pump system that includes a first roughing pump, a second roughing pump, and a turbomolecular pump, the turbomolecular pump being in fluid communication with one or both of the first roughing pump and the second roughing pump. The vacuum source 110 may also be a gas line connected to a vacuum pump or pumps, such as a facility vacuum.
In some implementations, a roughing pump, such as a dry mechanical pump, may be used to draw down pressure in the contactor. Rotary claw pumps, blower pumps, and/or booster pumps may be used, sometimes in combination, to provide roughing pump functionality. In some implementations, as the pressure in the contactor decreases, the roughing pump may be disengaged and a high-vacuum pump may be engaged to further draw down the pressure in the contactor.
For example, a turbomolecular pump, or turbopump, may be used to evacuate molecular-flow regime gas that remains in the contactor. Turbomolecular pumps may include a number of concentric, stacked rotating turbine blades interleaved with concentric, stationary turbine blades. As the turbine blades rotate, they impact gas molecules travelling into the throat of the turbomolecular pump and are forced through the turbine blade stack. A turbomolecular pump may be connected in series with a roughing pump downstream to assist in the evacuation of gas from the contactor. In some implementations, the same roughing pump or pumps may be used as the roughing pump downstream from the turbomolecular pump and as the roughing pump used in the initial draw-down. In such implementations, the foreline of the roughing pump(s) may be configured to be switchable, for example, using valves, between being directly connected with the contactor and being indirectly connected with the contactor via the turbomolecular pump. The turbomolecular pump may be kept spinning even when not being used to draw a vacuum in the contactor, and the valving system used may be able to isolate the turbomolecular pump from gas in the viscous flow regime while in this state to prevent damage to the turbomolecular pump.
Another example of a high-vacuum pump that may be used, either by itself or in combination with other high-vacuum pumps, is a cryopump. Cryopumps are devices that can be cooled to very low temperatures so as to trap gases and vapors through condensation. A cryopump, for example, may include a large surface that is cooled using, for example, helium or liquid nitrogen (or other suitable cooling mechanism). Any gas within, for example, a chamber that is in contact with the surface may condense on the surface and then freeze, thus reducing the amount of free gas within the chamber (thus reducing the gas pressure in the chamber). Cryopumps may be particularly useful for trapping water vapor, although cryopumps may also be used to trap other gases as well.
Additional features of the electroplating system are described in
An anode 124 is disposed below the wafer within the plating bath 114 and is separated from the wafer region by a plating membrane 125, preferably an ion selective membrane. For example, Nafion™ cationic exchange membrane (CEM) may be used. The region below the anodic membrane is often referred to as an “anode chamber.” The ion-selective anode membrane 125 allows ionic communication between the anodic and cathodic regions of the plating cell, while preventing the particles generated at the anode from entering the proximity of the wafer and contaminating it. The anode membrane is also useful in redistributing current flow during the plating process and thereby improving the plating uniformity. Ion exchange membranes, such as cationic exchange membranes, are especially suitable for these applications. These membranes are typically made of ionomeric materials, such as perfluorinated co-polymers containing sulfonic groups (e.g. Nafion™), sulfonated polyimides, and other materials known to those of skill in the art to be suitable for cation exchange. Selected examples of suitable Nafion™ membranes include N324 and N424 membranes available from Dupont de Nemours Co.
During plating, the ions from the electroplating solution are deposited on the substrate. The metal ions must diffuse through the diffusion boundary layer and into the via hole or other feature of the wafer. A typical way to assist the diffusion is through convection flow of the electroplating solution provided by a pump 126. Additionally, a vibration agitation or sonic agitation member may be used as well as wafer rotation which may be advantageous for uniform plating. For example, a vibration transducer 128 may be attached to the clamshell substrate holder 120.
During electroplating, the electroplating solution is continuously provided to the cell from the reservoir, and to the reservoir from the cell, by the plating cell flow loop which may operate as described herein. As illustrated in the example embodiment in
Other features of the electroplating system 100 in
A DC power supply 138 can be used to control current flow to the wafer 118. The power supply 138 has a negative output lead 140 electrically connected to wafer 118 through one or more slip rings, brushes and contacts (not shown); alternatively, the negative output lead may be electrically connected with the substrate holder 120, which may, in turn, be connected with the substrate. The positive output lead 142 of power supply 138 is electrically connected to an anode 124 located in plating bath 114. The power supply 138, a reference electrode 134, and a contact sense lead (not shown) can be connected to a system controller 144, which allows, among other functions, modulation of current and potential provided to the elements of electroplating cell. For example, the controller may allow electroplating in potential-controlled and current-controlled regimes. The controller may include program instructions specifying current and voltage levels that need to be applied to various elements of the plating cell, as well as times at which these levels need to be changed. When forward current is applied, the power supply 138 biases the wafer 118 to have a negative potential relative to anode 124. This causes an electrical current to flow from anode 124 to the wafer 118, and an electrochemical reduction (e.g. Cu2++2e−=Cu0) occurs on the wafer surface (the cathode), which results in the deposition of the electrically conductive layer (e.g. copper) on the surfaces of the wafer.
The system may also include a heater 152 for maintaining the temperature of the electroplating solution at a specific level. The electroplating solution may be used to transfer the heat to the other elements of the plating bath. For example, when a wafer 118 is loaded into the plating bath, the heater 152 and the pump 126 may be turned on to circulate the electroplating solution through the electroplating system 100 until the temperature throughout the apparatus becomes substantially uniform. In one embodiment the heater is connected to the system controller 144. The system controller 144 may be connected to a thermocouple to receive feedback of the electroplating solution temperature within the electroplating apparatus and determine the need for additional heating.
The controller will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and/or digital input/output connections, stepper motor controller boards, etc. In certain embodiments, the controller controls all of the activities of the electroplating apparatus. Non-transitory machine-readable media containing instructions for controlling process operations in accordance with the present embodiments may be coupled to the system controller.
Typically there will be a user interface associated with controller 144. The user interface may include a display screen, graphical software displays of the apparatus and/or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc. The computer program code for controlling electroplating processes can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program. One example of a plating apparatus that may be used according to the embodiments herein is the Lam Research Sabre tool. Electrodeposition can be performed in components that form a larger electrodeposition apparatus.
The system 100 of
The electroplating systems described herein may be implemented in various manners in order to control the dissolved gas concentration in the electroplating solution.
Here in system 400, a valve 460 is included between the contactor 408 and the vacuum source 410 and is configured to control the application of the vacuum to the contactor 408. In some implementations, the valve 460 may be configured to be fully open and thereby allow the maximum amount of flow through the valve, fully closed and thereby not allow any flow through the valve, or a plurality of partially open configurations to allow different amounts of flow through the valve. The valve 460 is also connected to the system controller 444 which is configured to control the operation of valve 460, such as causing it to be fully open, partially open, or closed. By controlling the operation of the valve 460, the controller 444 is able to control the application of the vacuum to the contactor 408, control the degassing of the contactor 408, and control the dissolved gas concentration in the electroplating solution.
The system 400 may also include one or more sensors that are connected to the controller 444 and used to provide feedback for controlling operation of the contactor 408, such as operation of the valve 460 and the application of the vacuum source 410 to the contactor 408. In some implementations, the system 400 may include one or more gas sensors 462 configured to detect and/or determine the concentration of a gas within the electroplating solution. The gas sensors 462 may be positioned in various locations within the system 400, such as in one or more of the electroplating cells 402 including the plating bath of the cell (114 in
The gas sensors are configured to detect one or more gases in the electroplating, such as oxygen or nitrogen. Examples of some such gas sensors include a stainless-steel pressure sensor that is compatible with acid. As described in more detail below, directly detecting and measuring the gas concentration in the electroplating solution enables the control of the vacuum applied to contactor and the resulting degassing by the contactor in order to control the concentration of the dissolved gas in the electroplating solution.
The system may also include one or more pressure sensors 464 configured to measure the pressure within the contactor 408. The controller 444 is connected to the one or more pressure sensors 464 and configured to receive pressure data generated by the one or more pressure sensors 464. Detecting and measuring the pressure in contactor may be used as a proxy or surrogate for the dissolved gas concentration in the electroplating solution and enable the control the dissolved gas concentration in the electroplating solution. In some implementations, the pressure within the contactor has a positive correlation with the dissolved gas concentration such that increasing the contactor pressure increases the dissolved gas concentration and decreasing the contactor pressure decreases the dissolved gas concentration. In some instances, the contactor pressure and dissolved gas concentration may have a linear, or substantially linear (e.g., within 85% of linear), relationship as illustrated in
Referring back to
In some implementations, the contactor pressure may be controlled with a pressure regulator. The pressure regulator is configured to maintain a constant pressure, or substantially constant pressure (e.g. within 15%), within the contactor by adjusting the amount of vacuum applied to the contactor and causing the contactor membrane to maintain an equilibrium between liquid inside on the shell side and the vacuum on the lumen side. Maintaining a constant, or substantially constant, contactor pressure results in a constant, or substantially constant, dissolved gas concentration of the liquid that flows out of the contactor. For instance, referring back to
Examples of electroplating systems with pressure regulators are shown in
In some implementations, the pressure regulator may be exposed to the electroplating solution which may result in metal salt and/or acid buildup in the regulator which can cause it to fail. This may occur because some of the electroplating solution may weep through the membrane and travel to the regulator. Many pressure regulators are unable to withstand the exposure to the corrosive electroplating solution. This exposure may be avoided by adding a liquid trap to protect the pressure regulator which may require, in some instances, hardware to sense trap levels, to drain the trap, and monitor the life of the regulator. These features may be included in some electroplating systems that use a pressure regulator.
Another implementation of the electroplating system may position a contactor in parallel with the plating cell flow loop such that fluid is simultaneously flowing through both the plating cell flow loop and the contactor. In some such implementations, the vacuum may be constantly applied to the contactor which results in a constant dissolved gas removal rate by the contactor. The flow rate through the contactor may therefore affect the resulting dissolved gas concentration of the electroplating solution flowed through the contactor. For example, the slower fluid flows through the contactor with the constant dissolved gas removal rate, the more dissolved gas will be removed from the fluid and the lower the resulting dissolved gas concentration of the electroplating fluid. Conversely, the faster fluid flows through the contactor with the constant dissolved gas removal rate, the less dissolved gas will be removed from the electroplating solution. Accordingly, during instances in which flow rates are high, such as during electroplating, less dissolved gas may be removed from the solution than during instances in which the flow rates are low, such as during system idle.
This is illustrated in
In some embodiments, the flow rate through the contactor 708 may be controlled in various manners, such as using a static or adjustable control with a flow restrictor that could be inserted and adjusted, or actively controlled with a control valve 761 and feedback control based on the measured dissolved gas concentration in the system 700 using one or more of the sensors provided above, such as gas sensor 762. Although not shown in
The contactor may be positioned in various locations within the electroplating system. This may include, for example, interposed between the electroplating cells and the reservoir as shown in
Various techniques described herein are used to control and maintain dissolved gas concentrations in the electroplating solution, including some that rely on feedback while others do not rely on feedback.
In block 803, the pressure is controlled in the contactor in order to cause the concentration of the dissolved gas in the electroplating solution to be maintained within a first range. In some implementations, this pressure control includes adjusting the contactor pressure by increasing and decreasing contactor pressure within a desired pressure range which in turn maintains the dissolved gas concentration within a desired concentration range. For example, as provided above and illustrated in
As provided herein, the contactor pressure may be decreased by applying the vacuum to the contactor and increased by stopping the application of the vacuum and continuing to flow electroplating solution through the contactor. In some implementations, the vacuum may be applied by connecting the vacuum source to the contactor by, for example, opening a valve between the contactor and the vacuum source, such as the control valve 460 of system 400 in
In some embodiments, the contactor pressure may be repeatedly increased and decreased to maintain the contactor pressure within a desired pressure range, and therefore the dissolved gas concentration within a desired concentration range. For example, once the the dissolved gas concentration has been reduced by reducing the contactor pressure, the dissolved gas concentration may increase again due to the nature of electroplating systems, such as various operations performed in the system, whether a wafer is in or not in an electroplating cell, and dissolved gas uptake by the electroplating solution. The contactor is used to remove some of this dissolved gas concentration, but these various operations and states nevertheless result in gas being added back into the solution. Accordingly, the dissolved gas concentration of the electroplating solution may repeatedly, or cyclically, increase and decrease at one or more frequencies.
This concept is further illustrated with
More specifically in
Controlling the contactor pressure by repeatedly increasing and decreasing the contactor pressure is further illustrated in
After block 1003B, blocks 1003A and 1003B may again be repeated. Repeatedly increasing and decreasing the pressure in the contactor by repeatedly applying the vacuum to the contactor and stopping the applying of the vacuum to the contactor, thereby controls and maintains the concentration of the dissolved gas within a first range. This may result in adjusting the contactor pressure between two pressures. For instance, at a first contactor pressure, the vacuum is applied to the contactor to lower the contactor pressure to a second contactor pressure, at which point the vacuum application will be stopped and the contactor pressure will rise again to the first contactor pressure. This cycle may be repeated and may result, given the correlations between pressure and dissolved gas described herein, in the dissolved gas concentration also increasing and decreasing within the range.
Blocks 1003A and 1003B may be repeated at different frequencies based on various factors and considerations. For example, the dissolved gas concentration of the electroplating solution may be affected by a wafer being positioned within a cell because each cell has a large surface area of electroplating solution within the cell that is covered by the wafer when it is positioned in the cell, and that is exposed to the environment when a wafer is not positioned therein. The more surface area of the electroplating solution is exposed to the environment, the higher and faster the resulting gas uptake by the electroplating solution and the higher the resulting dissolved gas concentration. Conversely, the less surface area exposed to the environment, the less gas uptake occurs. Because of this, the dissolved gas concertation may increase at a greater rate when a wafer is not positioned in a cell than when a wafer is positioned in the cell.
The techniques provided herein may be configured to account for differing gas uptake rates, including those based on whether a wafer is or is not in an electroplating cell. In some embodiments, the frequency at which the vacuum is and is not applied may be at one frequency when a wafer is positioned within a cell, and at a different frequency when a wafer is not positioned within the cell. When the gas uptake is at a greater rate when a wafer is not positioned in a cell, as compared to when a wafer is in the cell, the application of the vacuum and the stopping of the vacuum application may be performed at a higher frequency when the wafer is not in the cell, than when the wafer is in the cell.
For example, at time t1 the vacuum is applied, at time t2 the vacuum is stopped being applied, at time t3 the vacuum is applied, at time t4 the vacuum is stopped being applied, and at time t5 the vacuum is applied again. In the “wafer in” section, the time between ti and t3 is greater than the “wafer out” section between t3 and t5, indicating that the frequency of applying and stopping applying the vacuum to the contactor is greater when the wafer is out of the cell. In
Controlling the contactor pressure similar to
As mentioned above, some embodiments may use feedback from one or more sensors to control the contactor pressure. This may include detecting the contactor pressure and controlling the contactor pressure based on this pressure detection, and/or detecting the dissolved gas concentration and controlling the contactor pressure based on this concentration detection.
If it is detected or determined that the contactor pressure has reached a first contactor pressure, such as an upper threshold, then the contactor pressure may be decreased by performing block 1203A and applying the vacuum to the contactor as described herein, such as block 1003A above. Referring back to
Similar to described above, blocks 1203A and 1203B may also be repeated at various frequencies based on the detected contactor pressure. For example, referring back to
In some feedback-based embodiments, the contactor pressure control may be based on detecting the dissolved gas concentration and controlling the contactor pressure based on this concentration detection.
If it is determined that the dissolved gas concentration has reached a first concentration level, such as an upper threshold, then the contactor pressure may be decreased by performing block 1303A and applying the vacuum to the contactor as described herein, such as block 1003A. For example, referring back to
In some embodiments, the contactor pressure may be controlled based on both detected contactor pressure and measured dissolved gas concentration.
In some implementations, it may be advantageous to have different dissolved gas concentrations based on different states of the electroplating system, such as during electroplating, at idle, wafer in, and/or wafer out. For example, the contactor pressure may be controlled to cause a first dissolved gas concentration when a cell has a wafer positioned therein, and a different, second dissolved gas concentration when the cell does not have a wafer positioned therein. In another example, the contactor pressure may be controlled to cause a first dissolved gas concentration when electroplating is occurring and a different, second dissolved gas concentration when electroplating is not occurring. Similarly, the contactor pressure may be controlled to cause different dissolved gas concentrations during different stages of an electroplating process. This may advantageously be used to adjust for different byproduct levels during different the processing and/or to cause different bath and deposited material properties during the electroplating.
As provided above, the electroplating system may include a pressure regulator connected to the contactor as described above in
In some embodiments, the electroplating system may include a contactor in parallel with the electroplating flow loop as described above and shown in
As described above, the flow rate of fluid through the contactor affects the actual amount of gas removed from the fluid. The faster the flow rate, the lower the actual gas removed, for instance. Accordingly, in some embodiments, the technique of
As provided above, some techniques account for different states of the electroplating cells or systems. These states may include whether a wafer is positioned in the bath/solution or out of the bath solution. In some such embodiments, the dissolved gas concentration, such as the dissolved oxygen concentration, may be at a relatively lower concentration when a wafer is positioned in the bath and at a relatively higher concentration when the wafer is out of the bath. These states may also include a wafer in a cell while electroplating occurs and while electroplating does not occur. Again, the dissolved gas concentration may be higher during one of these states than the other and the techniques may control the contactor pressure in order to account for these states.
For instance, when the concentration is at a relatively higher concentration during one of these states as compared to another state, the contactor pressure may be increased and decreased, as described above, at a higher frequency. The range at which the contactor pressure is maintained may also be higher when the concentration is higher during one of these states. Referring to
In various embodiments, the dissolved gas may be dissolved oxygen, and this dissolved oxygen concentration in a copper electroplating solution may be maintained between about 1 ppm and 10 ppm, or between about 2 ppm and about 8 ppm. In some embodiments, the dissolved oxygen concentration in a copper electroplating solution is maintained between about 3 ppm and 6 ppm. In further embodiments, the dissolved oxygen concentration in a copper electroplating solution is maintained between about 4.5 ppm and 6 ppm.
In various embodiments, the contactor pressures used to control dissolved oxygen concentrations are between about 0.2 Atm and 2 Atm. In certain embodiments, the contactor pressures used to control dissolved oxygen concentrations are between about 0.2 Amt and about 1 Atm, about 0.3 and about 0.7 Atm. In further embodiments, the contactor pressures used to control dissolved oxygen concentrations are between about 0.4 Atm and about 0.6 Atm. In certain implementations, the contractor pressures are applied to flowing or quiescent electroplating solution under conditions that reach an equilibrium concentration of the dissolved oxygen in the electroplating solution.
While controlling the dissolved oxygen concentration in the electroplating solution may be a goal of certain disclosed embodiments, various other parameters may impact the dissolved oxygen concentration. These other parameters may include the temperature of the electroplating solution and/or the composition of the electrolyte.
The systems provided herein are configured to perform any of the techniques described herein. This may include a system controller employed to control process conditions and hardware states of the electroplating systems described herein, including controllers 144 and 444, for example. The system controller may include one or more memory devices, one or more mass storage devices, and one or more processors. The processor may include a CPU or computer, analog and/or digital input/output connections, stepper motor controller boards, etc.
In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, electroplating cells, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases and fluids, the vacuum source, pumps, electroplating, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
Without limitation, example systems may include a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.
As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.
It is to be understood that the use of ordinal indicators, e.g., (a), (b), (c), . . . , herein is for organizational purposes only, and is not intended to convey any particular sequence or importance to the items associated with each ordinal indicator. For example, “(a) obtain information regarding velocity and (b) obtain information regarding position” would be inclusive of obtaining information regarding position before obtaining information regarding velocity, obtaining information regarding velocity before obtaining information regarding position, and obtaining information regarding position simultaneously with obtaining information regarding velocity. There may nonetheless be instances in which some items associated with ordinal indicators may inherently require a particular sequence, e.g., “(a) obtain information regarding velocity, (b) determine a first acceleration based on the information regarding velocity, and (c) obtain information regarding position”; in this example, (a) would need to be performed (b) since (b) relies on information obtained in (a)-(c), however, could be performed before or after either of (a) or (b).
Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.
Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.
A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/024762 | 4/14/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63201170 | Apr 2021 | US |
