Dynamic liquid touch point control

Abstract

Discussed herein are methods, apparatus, and systems for electroplating semiconductor substrates. Generally, the disclosed techniques involve dynamically determining a liquid touch point position at which a first substrate initially begins immersing in electrolyte, and then feeding this liquid touch point position forward for controlling immersion of a second substrate that is electroplated after the first substrate. The liquid touch point position is determined by applying a potential to the first substrate, detecting a time at which a current supplied to the substrate reaches a threshold current, and determining a location of the substrate / substrate support / lift at the time when the current reaches the threshold current. This dynamic technique provides substantial benefits over previous techniques for determining the liquid touch point position, resulting in high quality plating results that are extremely stable and repeatable.

Description

DYNAMIC LIQUID TOUCH POINT CONTROLRELATED APPLICATION(S)

[0001] 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 its entirety and for all purposes.BACKGROUND

[0002] The present disclosure relates generally to electroplating. More specifically, disclosed herein are methods, apparatus, and systems for controlling the immersion of a semiconductor substrate in electrolyte.The background description provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0003] Various examples herein relate to methods, apparatus, controllers, and systems for electroplating substrates. Notably, the techniques described herein allow for dynamic measurement of a liquid touch point during electroplating. The liquid touch point relates to a position where the substrate first begins contacting electrolyte. Dynamic measurement of the liquid touch point during electroplating allows for substantial improvements in process repeatability and resulting film qualify. In many examples, the liquid touch point is measured during immersion of a first substrate. The first substrate is electroplated and removed from the electroplating cell followed by introduction of a second substrate. The second substrate is then immersed in the electrolyte using an entry profile that assumes the second substrate will enter the electrolyte at the liquid touch point measured during immersion of the first substate.

[0004] In one aspect of the disclosed examples, a method of electroplating substrates including a first substrate and a second substrate is provided, the method including: (a) receiving the first substrate in a substrate support of an electroplating cell, the electroplating cell including: a vessel configured to hold electrolyte, a substrate support configured to support one of the substrates during electroplating, and a lift configured to control a position of the substrate support; (b) lowering the first substrate toward a surface of the electrolyte; (c) applying a potential to the first substrate while lowering the first substrate toward the surface of the electrolyte, where the potentialis applied to the first substrate both (i) before an initial immersion time for the first substrate, and (ii) at the initial immersion time for the first substrate, where the initial immersion time for the first substrate is a time at which the first substrate begins contacting the electrolyte; (d) determining the initial immersion time for the first substrate, the initial immersion time for the first substrate corresponding to a time at which a current supplied to the first substrate reaches a threshold current; (e) determining a liquid touch point position for the first substrate, the liquid touch point position for the first substrate corresponding to a position of the lift at the initial immersion time for the first substrate; (f) electroplating the first substrate while the first substrate is immersed in the electrolyte, and then removing the first substrate from the electroplating cell; (g) receiving the second substrate in the substrate support of the electroplating cell; and (h) lowering the second substrate toward the surface of the electrolyte using an entry profile that indicates the second substrate will begin entering the electrolyte at the liquid touch point position for the first substrate determined in (e).

[0005] In some examples, the method is repeated on additional substrates, where each substrate is lowered toward the surface of the electrolyte using an entry profile that indicates that the substrate will begin entering the electrolyte at the liquid touch point position determined for a previously electroplated substrate. In some examples, a composition of the electrolyte changes over a course of plating the additional substrates, and the liquid touch point position determined in (e) changes in response to the changing composition of the electrolyte. In some such examples, the composition of the electrolyte changes with respect to one or more accelerator, suppressor, or leveler.

[0006] In some examples, the potential applied to the first substrate in (c) is a constant potential. In other examples, the potential applied to the first substrate in (c) is a non-constant potential.

[0007] In various examples, both the first substrate and the second substrate are tilted with respect to the surface of the electrolyte as they are lowered toward the electrolyte, and both the first substrate and the second substrate are rotated about an axis as they are lowered toward the electrolyte. Such tilting and rotation can help prevent bubble entrapment under the substrates. In some such examples, the entry profile in (h) specifies one or more of (i) a z-speed profile for the second substrate as the second substrate is immersed into the electrolyte, (ii) a tilt profile for the second substrate as the second substrate is immersed into the electrolyte, and / or a rotation speed profile for the second substrate as the second substrate is immersed into the electrolyte.

[0008] In various examples, the electroplating cell is powered by a power supply, a position of the lift is controlled by a lift controller, and the power supply sends a high speed digital signal tothe lift controller when the current supplied to the first substrate reaches the threshold current. In some such examples, the lift controller immediately saves an instantaneous position of the lift upon receipt of the high speed digital signal from the power supply, the instantaneous position of the lift at that time corresponding to the liquid touch point position for the first substrate.

[0009] In some examples, the method further includes calculating an adjusted liquid touch point position based on the liquid touch point position for the first substrate determined in (e) and a liquid touch point position offset, where the entry profile for the second substrate indicates that the second substrate will begin entering the electrolyte at the adjusted liquid touch point position. In these or other examples, the method may further include providing the liquid touch point position for the first substrate to a factory host.

[0010] In another aspect of the disclosed examples, an apparatus for electroplating substrates including a first substrate and a second substrate is provided, the apparatus including: a power supply; a vessel configured to hold electrolyte; a substrate support configured to support one of the substrates during electroplating; a lift configured to control a position of the substrate support; and a controller configured to cause: (a) receiving the first substrate in the substrate support, (b) lowering the first substrate toward a surface of the electrolyte, (c) applying a potential to the first substrate while lowering the first substrate toward the surface of the electrolyte, where the potential is applied to the first substrate both (i) before an initial immersion time for the first substrate, and (ii) at the initial immersion time for the first substrate, where the initial immersion time for the first substrate is a time at which the first substrate begins contacting the electrolyte, (d) determining the initial immersion time for the first substrate, the initial immersion time for the first substrate corresponding to a time at which a current supplied to the first substrate reaches a threshold current, (e) determining a liquid touch point position for the first substrate, the liquid touch point position for the first substrate corresponding to a position of the lift at the initial immersion time for the first substrate; (I) electroplating the first substrate while the first substrate is immersed in the electrolyte, and then removing the first substrate from the vessel; (g) receiving the second substrate in the substrate support; and (h) lowering the second substrate toward the surface of the electrolyte using an entry profile that indicates the second substrate will begin entering the electrolyte at the liquid touch point position for the first substrate determined in (e).

[0011] In some examples, the apparatus further includes a lift controller that controls the position of the lift. In some such examples, the power supply sends a high speed digital signal to the lift controller when the current supplied to the first substrate reaches the threshold current. In various cases, the lift controller immediately saves an instantaneous position of the lift upon receipt of thehigh speed digital signal from the power supply, the instantaneous position of the lift at that time corresponding to the liquid touch point position for the first substrate.

[0012] In some examples, the controller is further configured to cause repeating (a)-(h) on additional substrates, where each substrate is lowered toward the surface of the electrolyte using an entry profile that indicates that the substrate will begin entering the electrolyte at the liquid touch point position determined for a previously electroplated substrate. In some such examples, a composition of the electrolyte changes over a course of plating the additional substrates, and the liquid touch point position determined in (e) changes in response to the changing composition of the electrolyte. In some cases, the composition of the electrolyte changes with respect to one or more accelerator, suppressor, or leveler.

[0013] In some cases, the potential applied to the first substrate in (c) is a constant potential. In some other cases, the potential applied to the first substrate in (c) is a non-constant potential.

[0014] In another aspect of the disclosed examples, a method of dynamically measuring a liquid touch point while electroplating a plurality of substrates including at least a first substrate and a second substrate is provided, the method including: (a) while immersing a first substrate in electrolyte in an electroplating cell, measuring a liquid touch point at which the first substrate first begins to contact the electrolyte; (b) electroplating metal onto the first substrate and then removing the first substrate from the electroplating cell; (c) immersing a second substrate in the electrolyte using an entry profile that indicates that the second substrate will begin entering the electrolyte at the liquid touch point measured with respect to the first substrate in (a); and (d) electroplating metal onto the second substrate.

[0015] These and other aspects are described further below with reference to the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 A illustrates bubble entrapment under a substrate during electroplating.

[0017] FIG. IB depicts a substrate that is tilted during immersion to allow a path for bubbles to escape from under the substrate.

[0018] FIGS. 2A-2D show a substrate over the course of an immersion process where the substrate is tilted and rotated prior to immersion.

[0019] FIG. 3 is a flow chart describing a method of electroplating substrates according to one aspect of the invention.

[0020] FIG. 4 is a flow chart describing a method of electroplating substrates according to one aspect of the invention.

[0021] FIG. 5 depicts a simplified view of an electroplating cell according to various examplesherein.

[0022] FIGS. 6 and 7 show simplified views of electroplating apparatuses having multiple electroplating chambers therein.DETAILED DESCRIPTION

[0023] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented examples. The disclosed examples 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 examples. While the disclosed examples will be described in conjunction with the specific examples, it will be understood that it is not intended to limit the disclosed examples.

[0024] 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. In addition to semiconductor wafers, other work pieces that may take advantage of the disclosed aspects include various articles, such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micromechanical devices, and the like.

[0025] There are many electroplating applications in the context of semiconductor fabrication. In a typical semiconductor electroplating process, a substrate is loaded onto a substrate support, which then lowers the substrate into an electrolyte. One issue that can arise during immersion is entrapment of air under the bottom surface of the substrate.

[0026] FIG. 1A illustrates a cross-sectional diagram of a typical bubble entrapment scenario arising in an electroplating system 101. A horizontally oriented substrate 103 is lowered toward an electrolyte 107 in a vessel 105 along a vertical z-axis and ultimately immersed in the electrolyte 107. Vertical immersion of the horizontally oriented substrate 103 results in air bubbles 109 being trapped below the bottom (plating surface) of the substrate 103. The entrapped air prevents the substrate from contacting the electrolyte, thus hindering or preventing electroplating at the location where the entrapped air is located.

[0027] To avoid entrapping air under the substrate, the substrate support is often tilted prior to and / or during immersion. For example, the substrate can be tilted relative to a plane defined by a surface of the electrolyte while being introduced into the electrolyte along a vertical path (e.g.,along a z-axis). FIG. IB illustrates an electroplating system 112 operating under this scenario, where substrate 103 is immersed in electrolyte 107 along a z-axis, while the substrate is also tilted relative to the surface of the electrolyte at angle 9. Using angled immersion, bubbles 109 that would otherwise be trapped are aided by buoyancy and escape along the tilted bottom surface of the substrate 103. Another advantage related to tilted immersion is that a single wetting wavefront is created, thereby avoiding issues with convergent wetting fronts.

[0028] Bubble entrapment can be further reduced by rotating the substrate before and / or during immersion. FIGS. 2A-2D depict perspective diagrams outlining certain aspects of a substrate immersion method where the substrate is both tilted and rotated before and during immersion. FIG. 2A shows that the substrate 240 travels a linear distance 246 before entering electrolyte 244 in a plating bath 242. FIG. 2B shows that substrate 240 is tilted from the horizontal (e.g., horizontal being parallel to the surface of the electrolyte 244). In various cases, the tilt angle may be between about 1 degree and about 5 degrees, in some cases between about 3 degrees and about 5 degrees. A leading edge of the substrate entering the electrolyte creates a single wetting wave front. In various examples, the angle at which the substrate is tilted may be changed during immersion. In such examples, the “swing speed” (e.g., the speed at which the wafer is tilted from horizontal to 0, or from 9 to horizontal) may be controlled to minimize air entrapment and otherwise promote high quality plating results. In various examples, the swing speed of the substrate may be between about 0.25 and about 10 degrees per second, in some cases between about 0.25 and about 1.5 degrees per second. In various cases, the tilt angle, rotation speed, and z-speed can be controlled independently or on conjunction with one another to minimize bubble entrapment, as discussed further below.

[0029] As shown in FIG. 2C. the substrate 240 can also be rotated during immersion. Like tilting, substrate rotation can be implemented any time along the substrate’s vertical trajectory to electrolyte 244, as long as the substrate is rotating upon entry into electrolyte 244. FIG. 2D depicts the substrate 240, tilted and rotating, as it is being immersed in electrolyte 244. Example rotation speeds for the substrate 240 may be between about 10 rpm and about 180 rpm for a 200 mm diameter wafer, between about 5 rpm and about 180 rpm for a 300 mm wafer, and between about 5 rpm and about 150 rpm for a 450 mm wafer. In some cases, different rotation speeds can be used for immersion (a first rotation speed) vs. plating (a second rotation speed) vs. post-plating (a third rotation speed). In some cases, the rotation speed may change over the course of immersion.

[0030] The substrate immersion process can be carefully controlled to produce desired hydrodynamic conditions, thereby substantially reducing the risk and degree of air entrapmentunder the substrate. For instance, factors that may be controlled during immersion include, but are not limited to, (1) the z-speed at which the substrate support / substrate are lowered into the electrolyte; (2) the angle at which the substrate support / substrate are positioned with respect to the surface of the electrolyte; and (3) the speed at which the substrate support / substrate are rotated about their respective axes. Each of these factors can be controlled in a variable manner to produce desired conditions, independently or in conjunction with one another.

[0031] In an example immersion process, a substrate is positioned in a substrate support, which tilts and rotates the substrate as the substrate is immersed in electrolyte. The z-speed at which the substrate support and substrate are lowered may change over time. In other words, the z-speed profile (e.g., z-speed vs. time) may be non-constant, and may include at least one portion that is relatively slower and at least one portion that is relatively faster. Likewise, the angle at which the substrate support and substrate are positioned with respect to the surface of the electrolyte typically changes over the course of immersion and / or electroplating, as described above. In other words, the tilt profile (e.g., tilt angle vs. time) may be non-constant, and may include at least one portion where the substrate and substrate support are relatively more tilted with respect to the surface of the electrolyte, and at least one portion where the substrate and substrate support are relatively less tilted with respect to the surface of the electrolyte. Similarly, the speed at which the substrate support and substrate are rotated may change over the course of immersing the substrate. In other words, the rotation speed profile for rotating the substrate and substrate support (e.g., rotation speed vs. time) may be non-constant, and may include at least one portion where the substrate and substrate support are rotating relatively more slowly, and at least one portion where the substrate and substrate support are rotating relatively more quickly.

[0032] The z-speed profile, tilt profile, and rotation speed profile each relate to different aspects of the entry profile. Generally, the entry profile relates to the physical characteristics of how the substrate support is controlled over time during immersion. Entry profiles can be specifically tailored to achieve bubble-free wetting across the entire plating surface of the substrate, thereby significantly reducing wafer-level defects.

[0033] The entry profile (or one or more aspects thereof) may be hardcoded (e g., in software, firmware, etc.) to produce controlled z-speeds as various locations on the substrate are immersed to promote bubble-free entry and high quality plating results. Such tailored entry profiles may be referred to as Advanced Fx entry profiles. The hardcoding of an Advanced Fx entry profile involves generating a list of lift positions where the substrate is known to enter the electrolyte, and a list of z-speed profiles needed at those lift positions to achieve bubble-free entry. The lift positionat which the substrate first enters the electrolyte is referred to as the liquid touch point (LTP or LTP position). Because the LTP refers to the lift position, it may be reported as a z-height, referring to the height at which the substrate support and / or substrate are positioned, for example by a lift controller or other relevant controller. This hardcoding process can be challenging because the z-height at which the substrate begins to touch the electrolyte (e.g., LTP) and the z-height at which the substrate is fully immersed can be different across various electroplating tools, and can even vary' between multiple electroplating cells in a single electroplating tool.

[0034] Example electroplating tools that may be used to practice the techniques described herein include those in the Sabre® and Sabre® 3D product families, available from Lam Research Corporation of Fremont, CA. Such tools ty pically include hundreds of parts. Due to tolerance stackups and slight installation-related differences, there can be several millimeters difference in substrate immersion heights and related LTP positions. Because of these challenges, LTP position is typically measured during initial tool startup and during any major hardware upgrades to ensure that the actual LTP is known and recorded. The hardcoded lift positions in the Advanced Fx entry profiles can be setup relative to the LTP positions such that the z-speed can be matched during wafer immersion between various electroplating cells and tools. Knowledge of an accurate LTP position is important for designing and implementing an effective Advanced Fx entry profile. For instance, an entry profile that relies on an inaccurate LTP position can cause anonoptimal z-speed profile as the substrate is immersed. As a result, the substrate may be traveling at a z-speed that is slower and / or faster than desired as each portion of the substrate surface is immersed, thereby causing bubble entrapment, void formation, and otherwise low quality' plating results.

[0035] The techniques described herein utilize dynamic measurement of the LTP position. This measurement can be taken and fed forward to control subsequent immersion processes. For instance, the LTP position may be measured during an immersion process for a first substrate provided to an electroplating cell. After the first substrate is electroplated and removed from the electroplating cell, a second substrate is introduced to the electroplating cell. The LTP position measured during immersion of the first substrate is fed forward, and immersion of the second substrate is controlled (e g., the entry profile is designed / controlled) with the assumption that the second substrate will begin touching the electrolyte at the same LTP position measured during immersion of the first substrate. The actual LTP position for the second substrate may be measured during immersion of the second substrate, and this second measured LTP position can likewise be fed forward to control immersion of a third substrate with the assumption that the third substrate will begin touching the electrolyte at the same LTP position measured during immersion of thesecond substrate. In various cases, the LTP position may be measured every n substrates, where 1 < n < 100. It may be beneficial to measure the LTP position every time a substrate is immersed, such that the next substrate is always immersed using an entry' profile based on the most accurate LTP position. However, in some cases the LTP measurement may be done less frequently.

[0036] In the past, LTP measurement has been a laborious and error-prone process. LTP measurement has typically relied on a manual process that involves moving the substrate support between different lift positions and visually inspecting 'hether or not the bottom of the substrate support has become wet. In many cases, the desired resolution for the LTP measurement is about 10 pm or less in order to design an entry profile that adequately prevents bubble formation. As mentioned, previous LTP measurement processes are labor intensive, requiring repeatedly moving the substrate support between a lower position (at which immersion may or may not begin) and an upper position (at which an operator can inspect the substrate support). The lower position is gradually changed until the LTP position is visually identified. This process is time-intensive, and can easily take about 1-2 hours per electroplating cell, or about 3-6 hours per multi-cell electroplating tool in atypical fabrication environment.

[0037] Not only is this manual process repetitive and time-consuming, it’s also relatively subjective and prone to error, which can be costly in semiconductor manufacturing processes. For instance, low visibility and insufficient light within the tool can lead to errors in LTP measurement because an operator may not be able to effectively determine whether or not the bottom of the substrate support is wet. Another issue that can lead to poor LTP measurements relates to a certain waviness produced the surface of the electrolyte due to the presence of a pump that is constantly recirculating the electrolyte. This waviness causes some variability’ between LTP measurements depending on which portion of a wave (e.g.. the crest vs. the nadir vs. a position in between) first contacts the bottom of the substrate support. The yvaviness is further exacerbated by a fan filter unit and slightly over-pressurized air flo v inside the electroplating tool and at the exhaust near the surface of the electrolyte.

[0038] Because of the issues described above, LTP measurement is typically only performed on rare occasions, such as during initial tool setup and when major hardware changes occur, and during major cell preventative maintenance cycles. Such maintenance cycles are typically performed about once a month or once every few months, depending on how heavily the tool is being utilized.

[0039] Hoyvever, there are a number of factors that affect the actual LTP position, and these factors can cause the LTP position to change over time. For instance, the actual LTP position fora particular electroplating process can change based on the surface tension of the electrolyte, which changes the wetting behavior of the electrolyte. The electrolyte can include a number of additives (e.g., accelerator, suppressor, leveler, etc.) that affect the surface tension and wetting behavior of the electrolyte. As such, the composition of the electrolyte can affect the actual LTP position. The composition of the electrolyte is typically tailored to a particular electroplating process. As such, when the electroplating cell is used for a different electroplating process having a different composition of electrolyte, the LTP point can change as a result of the different electrolyte composition and related surface tension / wetting behavior. Moreover, even for a single type of electroplating process repeated on multiple substrates, the composition of the electrolyte can change overtime as additional substrates are processed. The concentration of the various additives in the electrolyte is typically monitored and controlled in a closed-loop fashion, but there is some temporal variability in additive concentration based on e.g., dosing, bleeding, consumption, breakdown, etc. These types of changes occur on relatively short timescales, and cannot be accurately captured and accounted for when LTP measurement occurs only about once a month. The variability, subjectivity, and inaccuracies involved in previous LTP measurement techniques have at times caused substantial process instabilities and non-optimal cell operation or even temporary shutdown, resulting in costly yield loss.

[0040] As such, there is a need for accurate, real time, substrate-to-substrate LTP position measurement and tracking to ensure that any variability in the LTP position is quickly and accurately captured. The measured LTP position can then be used when designing / controlling an entry profile for immersing a subsequent substrate in the electroplating cell. The result of the disclosed techniques is a highly controlled immersion process that provides desired z-speed, tilt, and rotation as each relevant portion of the substrate is immersed in electrolyte. Advantageously, these techniques can be used to maximize the quality of plating results by minimizing the risk of air entrapment under the plating surface of the substrate, thereby ensuring repeatably high quality plating results even in the face of changing electroplating conditions such as changing electrolyte composition. Testing has shown that these techniques provide accurate, stable, real-time LTP measurements, resulting in unique benefits that lead to substantial decreases in defects and costs, and related increases in process stability7and yield.

[0041] In various examples herein, the LTP position is measured during immersion of a substrate. Generally speaking, this measurement takes place by (1) determining when a current passing to the substrate during immersion reaches a threshold current, and (2) determining the position of the substrate and / or substrate support at the time when the current to the substratereaches the threshold current.

[0042] In many electroplating applications, a voltage (e.g., a fixed voltage) is applied to the substrate (e.g., between the substrate and the anode) prior to immersion. Such voltage may act to prevent dissolution of a seed layer present on a plating surface of the substrate. If such dissolution is not prevented, plating can be poor or non-existent in the regions where the seed layer was dissolved. The fixed voltage applied to the substrate causes the current provided to the substrate to spike as the substrate is immersed in electrolyte. This current can be monitored to determine when it passes a particular threshold current, indicating that the substrate has begun to become immersed in electrolyte. In other words, when the current reaches the threshold current, the substrate and substrate support are determined to be at the LTP position. At this time, the lift position for the substrate / substrate support are recorded. This recorded position is the measured LTP position.

[0043] The current passing to the substrate may be monitored for additional purposes, as well. For instance, in some cases the waveform applied to the substrate includes a first portion where the voltage applied to the substrate is potentiostatic and a second portion where the voltage applied to the substrate increases (e.g., often referred to as a voltage ramp or potential ramp). A threshold current may be used to determine when to switch from the first portion of the waveform to the second portion of the waveform. The threshold current for this purpose may have the same value or a different value than the threshold current used to determine LTP position. Likewise, even in cases where the voltage applied to the substrate during plating is entirely potentiostatic (e.g., without a voltage ramp), the current may be monitored, and a threshold current may be used to determine whether to continue or cease applying the potentiostatic voltage. Again, the threshold current in such an example may be the same or different from the threshold current used to determine LTP position. In some examples, a first threshold current used to determine LTP position may have a magnitude smaller or larger than a second threshold current used to determine when to switch from a potentiostatic to a potential ramp regime. Similarly, in some examples, a first threshold current used to determine LTP position may have a magnitude smaller or larger than a third threshold current used to determine whether to continue or cease applying a constant potential to the substrate.

[0044] In some examples, the threshold current may be as low as about 0.1 amp, or about 0.5 amp. In these or other examples, the threshold current may be as high as about 1 amp, or about 5 amp.

[0045] FIG. 3 presents a flow chart depicting a method of electroplating using the techniquesdescribed herein. While the method of FIG. 3 refers to a substrate and a subsequent substrate, it is understood that various steps in the method may be repeated as additional substrates are processed. This allows for each substrate to be immersed using an entry' profile that is based on the most recently measured LTP position. An example of the method of FIG. 3 is further described in relation to FIG. 4, discussed below.

[0046] The method of FIG. 3 begins with operation 301, where a substrate is loaded into a substrate support of an electroplating cell. The substrate support typically supports the substrate at its periphery such that a plating face of the substrate faces downwards toward the electrolyte. At operation 303, the substrate begins lowering toward the electrolyte. The substrate may be tilted and rotated before and / or during immersion. The substrate may be immersed using an entry profile that assumes the substrate will begin entering the electrolyte at a particular LTP position. This initial LTP position may be determined manually as described above, or it may be based on a past LTP measurement taken while immersing / plating a previous substrate. At operation 305, a potential (e.g., a constant potential in some cases, or a variable potential in other cases) is applied to the substrate. As the substrate begins entering the electrolyte, the current supplied to the substrate begins to spike. At operation 307, the time at which the current supplied to the substrate reaches a threshold current (It) is determined. This time is referred to as the initial immersion time (ti). and it indicates that the substrate, substrate support, and related lift have reached the LTP position and that the substrate has begun to wet. As such, at operation 309, the position of the lift at time ti is determined. This lift position is the measured LTP. In some examples, the measured LTP may be adjusted as described in relation to operation 421 of FIG. 4, discussed further below.

[0047] At operation 311. the substrate is electroplated and then removed from the electroplating cell. Next, at operation 313, a subsequent substrate is loaded into the substrate support in the electroplating cell. At operation 315, the subsequent substrate is lowered into the electrolyte using an entry' profile that assumes the subsequent substrate will enter the electrolyte at the LTP position determined in operation 309 with respect to the previous substrate. At operation 317, the subsequent substrate is plated and then removed from the electroplating cell.

[0048] Although FIG. 3 only refers to a substrate and a subsequent substrate, it is understood that several operations shown in FIG. 3 may be repeated on various substrates such that the substrate being processed at any given time is immersed using an entry' profile that assumes the substrate will enter the electrolyte at an LTP position recently measured in connection with a previously plated substrate (in many cases the immediately preceding substrate). For instance, with respect to FIG. 3, operations 305, 307, and 309 may be performed a first time on a firstsubstrate, and then may be repeated while immersing the subsequent substrate (e.g., a second substrate). The LTP position determined while immersing the subsequent substrate may be fed forward and used to determine an appropriate entry profile for immersing an additional substrate (e.g., a third substrate). This feed-forward technique can be extended to any number of substrates.

[0049] FIG. 4 presents another flowchart describing a method of electroplating substrates using the techniques described herein. Generally speaking, the method of FIG. 4 corresponds to the method of FIG. 3, with additional details provided. FIG. 4 illustrates various operations that may take place with respect to amain controller (left column of FIG. 4). a lift controller (middle column of FIG. 4), and a power supply (right column of FIG. 4). It should be understood that while FIG. 4 presents a particular set of controllers and interactions between them, the examples herein are not so limited, and can be achieved using any appropriate controller or set of controllers. Notably, the relevant controller(s) and power supply should be capable of high speed input / output in order to accurately measure the LTP position. As used herein, the term "high speed'’ as applied to digital input / output signals and controllers configured to receive and / or send them is intended to refer to signals / controllers that can provide at least sub-millisecond communication resolution.

[0050] The entire wafer immersion process can be completed within ~50 ms in some processes, to up to -500 ms in some other processes. The controller communication should be sufficiently fast and accurate to provide reliable and repeatable LTP measurements in a high volume manufacturing environment. Sub-millisecond inter-controller communication and reporting is desired for reliable LTP measurement. Delay or noise in the controller communication timing may cause drift in the LTP values from (i) the time when triggered by the power supply upon reaching the threshold current, to (ii) the time (and related position) reported by lift controller. Currently with enhanced firmware, state of the art controllers can enable control for these timings from within sub-millisecond down to several microsecond communication resolution.

[0051] The method of FIG. 4 begins at operation 401, where a command is sent from the main controller to the plating power supply to turn on the power supply. At operation 403, the power supply is turned on. At operation 405, the power supply checks the current being supplied to the substrate. This may be done on an ongoing / repeated basis. At operation 407, it is determined whether the current supplied to the substrate reaches a threshold current (It). If not, the method returns to operation 405 where the current to the substrate is checked again. Otherwise, the method continues with operation 409. As mentioned above, the time at which the current supplied to the substrate reaches the threshold current (It) is referred to as the initial immersion time (ti). At operation 409, which occurs at the initial immersion time (ti), the power supply provides a digitaloutput signal to the lift controller. This digital output signal indicates that the current supplied to the substrate has reached the threshold current, and therefore, the lift / substrate / substrate support have reached the LTP position and the substrate has begun to become immersed in electrolyte. The digital output signal from the power supply enables the lift controller to quickly and accurately determine the LTP based on the instantaneous position of the lift when the digital signal from the power supply is received by the lift controller.

[0052] Following another prong in the method of FIG. 4, operation 427 involves sending a Move to Plate command from the main controller to the lift controller. This Move to Plate command includes a stored LTP position, which may be based on a manually determined LTP, or more commonly, based on an LTP position previously measured using the techniques described herein (e.g., measured when plating a previously plated substrate). The method continues at operation 411, where the lift controller uses the LTP position provided in operation 427 to calculate the desired movement for achieving the Move to Plate command. This calculation may involve determining one or more aspects of an entry profile such as the z-speed profile, tilt profile, and / or rotation speed profile. As discussed above, an accurate LTP position is key to designing an entry profile that achieves bubble-free immersion. The method continues at operation 413, where the lift controller begins moving the lift / substrate / substrate support according to the calculated desired movement for the Move to Plate command. At operation 415, high speed digital input is enabled on the lift / lift controller. This high speed digital input on the lift controller allows for accurate determination of the lift position at relevant times, such as the initial immersion time (ti). At operation 417, the lift controller waits for the digital signal to be received from the pow er supply. This digital signal is further discussed in connection with operation 409.

[0053] Immediately upon receipt of the digital signal from the pow er supply, the lift controller determines the instantaneous position of the lift / substrate / substrate support, and saves this position as a captured LTP position in operation 419. At operation 421, the main controller calculates an adjusted LTP position based on the captured LTP position from operation 419 and an LTP offset. Alternatively, this calculation may be done by the lift controller and the result may be provided to the main controller. Certain LTP offsets maybe needed depending on the lag between the threshold current trigger and LTP reporting from the lift controller. These offsets can be automatically adjusted as the lags are repeatable / predictable. In some instances, the LTP position maybe defined as the touch point for the substrate holder as compared to the touch point for the actual substrate, hence requiring the need for certain other offsets. These offsets are typically constant, and in many cases are set when an electroplating tool or cell is first installed, and / orduring major maintenance cycles. The offsets may or may not change across various plating modules or tools. In some cases, the offset may be zero, such that no adjustment is needed (in this case, the adjusted LTP position referred to in operations 421, 423, and 425 may be the captured LTP position from operation 419). At operation 423, the adjusted LTP position calculated in operation 421 is optionally provided for Factory Host Monitoring. Such monitoring may be done to track the operation and performance of one or more electroplating tools, as desired. At operation 425, the stored LTP position is revised to reflect the adjusted LTP position calculated in operation 421. At this point, the substrate can be electroplated and removed from the plating cell.

[0054] The method can return to operation 427 after a new substrate is loaded into the electroplating cell. At this point, the mam power supply sends another Move to Plate command to the lift / lift controller. As mentioned above, this Move to Plate command includes the stored LTP position, which now reflects the adjusted LTP position measured / determined during plating of the previous substrate. The method is repeated, with the LTP position being measured / determined during each iteration (e.g., for every substrate, or for every n substrates). The measured / determined LTP position is constantly fed forward as part of the control process for immersing the next substrate. In this way, even small-scale variations in LTP resulting from changes in electrolyte composition and related wetting behavior can be accurately captured. These small-scale variations were not effectively perceptible using prior LTP measurement techniques, which for the reasons described above are typically only performed about once a month. The disclosed techniques provide a substantial increase in LTP measurement accuracy and feasible measurement frequency, thereby resulting in significant improvements in film quality. Moreover, the disclosed techniques provide a substantial increase in process stability-, with related decreases in bubble entrapment, film defects, and costly wasted substrates.

[0055] One advantage of the LTP measurement techniques herein is that they are substantially more precise compared to previous techniques. For instance, the desired process window for LTP position may have a range of about 0.5 mm or less, for example about 0.3 mm or less. This range refers to the maximum allowable difference between LTP measurements for a particular process, before it is determined that the electroplating cell is operating out of specification. When the LTP is dynamically measured substrate-to-substrate as described herein, the LTP measurements are typically within a range of about 0.05 mm of one another. Advantageously, this range is substantially lower than the maximum allowable range for the process window. By contrast, the range for manual LTP measurements is typically much higher, for example up to about 3.5 mm, which is far beyond the maximum allowable range. The disclosed techniques therefore providesignificant benefits compared to previous manual measurement methods.

[0056] Further, the techniques described herein completely remove the need for any manual LTP measurements. As such, the time, costs, and subjectivity associated with such measurements can be avoided, and throughput can be maximized. This benefit is substantial when considering all the time involved with manually measuring LTP for each electroplating cell every time an electroplating tool is installed, updated, or goes through monthly maintenance. Another benefit of the disclosed techniques is that they can be performed without impacting or delaying the immersion and plating processes.APPARATUS

[0057] The methods described herein can be performed by any appropriate electroplating apparatus. An appropriate electroplating apparatus includes at least a vessel configured to hold electrolyte, a power supply, a substrate support configured to support the substrate during electroplating, and a lift configured to control a position of the substrate support. In many cases, the apparatus further includes one or more controllers configured to control a position of the lift / substrate support, for example as described above in relation to FIGS. 3 and 4.

[0058] FIG. 5 presents an example of an electroplating cell in which electroplating may occur. Often, an electroplating apparatus includes one or more electroplating cells in which the substrates (e.g., wafers) are processed. Only one electroplating cell is shown in FIG. 5 to preserve clarity. To optimize bottom-up electroplating, additives (e.g., accelerators, suppressors, and levelers) are added to the electrolyte; however, an electrolyte with additives may react with the anode in undesirable ways. Therefore anodic and cathodic regions of the plating cell are sometimes separated by a membrane so that plating solutions of different composition may be used in each region. Plating solution in the cathodic region is called catholyte; and in the anodic region, anolyte. A number of engineering designs can be used in order to introduce anolyte and catholyte into the plating apparatus.

[0059] Referring to FIG. 5, a diagrammatical cross-sectional view of an electroplating apparatus 501 in accordance with one example is shown. The plating bath 503 contains the plating solution (having a composition as provided herein), which is shown at a level 505. The catholyte portion of this vessel is adapted for receiving substrates in a catholyte. A w afer 507 is immersed into the plating solution and is held by, e.g., a substrate support 509, mounted on a rotatable spindle 511, w hich allows rotation of substrate support 509 together with the w afer 507. A general description of a clamshell-type plating apparatus having aspects suitable for use with this invention isdescribed in detail in US Patent 6.156.167 issued to Patton et al., and US Patent 6,800.187 issued to Reid et al., which are incorporated herein by reference in their entireties.

[0060] An anode 513 is disposed below the wafer within the plating bath 503 and is separated from the wafer region by a membrane 515, 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 515 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. Detailed descriptions of suitable anodic membranes are provided in US Patents 6,126,798 and 6,569,299 issued to Reid et al., both incorporated herein by reference in their entireties. 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.

[0061] During plating the ions from the plating solution are deposited on the substrate. The metal ions must diffuse through the diffusion boundary layer and into the TSV hole or other feature. A typical way to assist the diffusion is through convection flow of the electroplating solution provided by the pump 517. Additionally, a vibration agitation or sonic agitation member may be used as well as wafer rotation. For example, a vibration transducer 508 may be attached to the substrate support 509.

[0062] The plating solution is continuously provided to plating bath 503 by the pump 517. Generally, the plating solution flows upwards through an ion-selective anode membrane 515 and a diffuser plate 519 to the center of wafer 507 and then radially outward and across wafer 507. The plating solution also may be provided into the anodic region of the bath from the side of the plating bath 503. The plating solution then overflows plating bath 503 to an overflow reservoir 521. The plating solution is then filtered (not shown) and returned to pump 517 completing the recirculation of the plating solution. In certain configurations of the plating cell, a distinct electrolyte is circulated through the portion of the plating cell in which the anode is contained while mixing with the main plating solution is prevented using sparingly permeable membranes or ion selective membranes.

[0063] A reference electrode 531 is located on the outside of the plating bath 503 in a separate chamber 533, which chamber is replenished by overflow from the plating bath 503. Alternatively, in some examples the reference electrode is positioned as close to the substrate surface as possible, and the reference electrode chamber is connected via a capillary tube or by another method, to the side of the wafer substrate or directly under the wafer substrate. In some of the preferred examples, the apparatus further includes contact sense leads that connect to the wafer periphery and which are configured to sense the potential of the metal seed layer at the periphery of the wafer but do not carry any current to the wafer.

[0064] A reference electrode 531 is typically employed when electroplating at a controlled potential is desired. The reference electrode 531 may be one of a variety of commonly used types such as mercury / mercury sulfate, silver chloride, saturated calomel, or copper metal. A contact sense lead in direct contact with the wafer 507 may be used in some examples, in addition to the reference electrode, for more accurate potential measurement (not shown).

[0065] A power supply 535 (e.g., DC power supply) can be used to control current flow to the wafer 507. The power supply 535 has a negative output lead 539 electrically connected to wafer 507 through one or more slip rings, brushes and contacts (not shown). The positive output lead 541 of pow er supply 535 is electrically connected to an anode 513 located in plating bath 503. The power supply 535, a reference electrode 531, and a contact sense lead (not shown) can be connected to a system controller 547, 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 535 biases the wafer 507 to have a negative potential relative to anode 513. This causes an electrical current to flow' from anode 513 to the wafer 507, and an electrochemical reduction (e.g. Cu2++ 2 e’ = Cu°) 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 w afer. An inert anode 514 may be installed below' the wafer 507 within the plating bath 503 and separated from the wafer region by the membrane 515.

[0066] The apparatus may also include a heater 545 for maintaining the temperature of the plating solution at a specific level. The plating solution may be used to transfer the heat to the other elements of the plating bath. For example, when a wafer 507 is loaded into the plating bath the heater 545 and the pump 517 may be turned on to circulate the plating solution through theelectroplating apparatus 501. until the temperature throughout the apparatus becomes substantially uniform. In one example the heater is connected to the system controller 547. The system controller 547 may be connected to a thermocouple to receive feedback of the plating solution temperature within the electroplating apparatus and determine the need for additional heating.

[0067] 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 examples, 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 examples may be coupled to the system controller.

[0068] Typically there will be a user interface associated with system controller 547. 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 examples herein is the Lam Research Sabre tool. Electrodeposition can be performed in components that form a larger electrodeposition apparatus.

[0069] FIG. 6 shows a schematic of a top view of an example electrodeposition apparatus. The electrodeposition apparatus 600 can include three separate electroplating modules 602, 604, and 606. The electrodeposition apparatus 600 can also include three separate modules 612, 614, and 616 configured for various process operations. For example, in some examples, one or more of modules 612, 614, and 616 may be a spin rinse drying (SRD) module. In other examples, one or more of the modules 612, 614, and 616 may be post-electrofill modules (PEMs), each configured to perform a function, such as edge bevel removal, backside etching, and acid cleaning of substrates after they have been processed by one of the electroplating modules 602. 604, and 606.

[0070] The electrodeposition apparatus 600 includes a central electrodeposition chamber 624. The central electrodeposition chamber 624 is a chamber that holds the chemical solution used as the electroplating solution in the electroplating modules 602, 604, and 606. The electrodeposition apparatus 600 also includes a dosing system 626 that may store and deliver additives for the electroplating solution. A chemical dilution module 622 may store and mix chemicals to be used as an etchant. A filtration and pumping unit 628 may filter the electroplating solution for thecentral electrodeposition chamber 624 and pump it to the electroplating modules.

[0071] A system controller 630 provides electronic and interface controls required to operate the electrodeposition apparatus 600. The system controller 630 (which may include one or more physical or logical controllers) controls some or all of the properties of the electrodeposition apparatus 600.

[0072] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 630 from various process tool sensors. The signals for controlling the process may be output on the analog and digital output connections of the process tool. Non-limiting examples of process tool sensors that may be monitored include mass flow controllers, pressure sensors (such as manometers), thermocouples, optical position sensors, etc. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain process conditions.

[0073] A hand-off tool 640 may select a substrate from a substrate cassette such as the cassette 642 or the cassette 644. The cassettes 642 or 644 may be front opening unified pods (FOUPs). A FOUP is an enclosure designed to hold substrates securely and safely in a controlled environment and to allow the substrates to be removed for processing or measurement by tools equipped with appropriate load ports and robotic handling systems. The hand-off tool 640 may hold the substrate using a vacuum attachment or some other attaching mechanism.

[0074] The hand-off tool 640 may interface with a wafer handling station 632, the cassettes 642 or 644, a transfer station 650, or an aligner 648. From the transfer station 650, a hand-off tool 646 may gain access to the substrate. The transfer station 650 may be a slot or a position from and to which hand-off tools 640 and 646 may pass substrates without going through the aligner 648. In some examples, however, to ensure that a substrate is properly aligned on the hand-off tool 646 for precision delivery to an electroplating module, the hand-off tool 646 may align the substrate with an aligner 648. The hand-off tool 646 may also deliver a substrate to one of the electroplating modules 602, 604, or 606 or to one of the three separate modules 612, 614, and 616 configured for various process operations.

[0075] An example of a process operation according to the methods described above may proceed as follows: (1) electrodeposit copper or another material onto a substrate in the electroplating module 604; (2) rinse and dry the substrate in SRD in module 612; and (3) perform edge bevel removal in module 614.

[0076] An apparatus configured to allow efficient cycling of substrates through sequential plating, rinsing, drying, and PEM process operations may be useful for implementations for usein a manufacturing environment. To accomplish this, the module 612 can be configured as a spin rinse dryer and an edge bevel removal chamber. With such a module 612, the substrate would only need to be transported between the electroplating module 604 and the module 612 for the copper plating and EBR operations. In some examples the methods described herein will be implemented in a system which comprises an electroplating apparatus and a stepper.

[0077] An alternative example of an electrodeposition apparatus 700 is schematically illustrated in FIG. 7. In this example, the electrodeposition apparatus 700 has a set of electroplating cells 707, each containing an electroplating bath, in a paired or multiple “duet” configuration. In addition to electroplating per se, the electrodeposition apparatus 700 may perform a variety of other electroplating related processes and sub-steps, such as spin-rinsing, spin-drying, metal and silicon wet etching, electroless deposition, pre-wetting and pre-chemical treating, reducing, annealing, electro-etching and / or electropolishing, photoresist stripping, and surface preactivation, for example. The electrodeposition apparatus 700 is shown schematically looking top down in FIG. 7, and only a single level or “floor” is revealed in the figure, but it is to be readily understood by one having ordinary skill in the art that such an apparatus, e g., the Lam Sabre™ 3D tool, can have two or more levels “stacked” on top of each other, each potentially having identical or different types of processing stations.

[0078] Referring once again to FIG. 7, the substrates 706 that are to be electroplated are generally fed to the electrodeposition apparatus 700 through a front end loading FOUP 701 and, in this example, are brought from the FOUP to the main substrate processing area of the electrodeposition apparatus 700 via a front-end robot 702 that can retract and move a substrate 706 driven by a spindle 703 in multiple dimensions from one station to another of the accessible stations — two front-end accessible stations 704 and also two front-end accessible stations 708 are shown in this example. The front-end accessible stations 704 and 708 may include, for example, pre-treatment stations, and spin rinse dry ing (SRD) stations. Lateral movement from side-to-side of the front-end robot 702 is accomplished utilizing robot track 702a. Each of the substrates 706 may be held by’ a cup / cone assembly (not shown) driven by a spindle 703 connected to a motor (not shown), and the motor may be attached to a mounting bracket 709. Also shown in this example are the four “duets” of electroplating cells 707, for a total of eight electroplating cells 707. A system controller (not shown) may be coupled to the electrodeposition apparatus 700 to control some or all of the properties of the electrodeposition apparatus 700. The system controller may be programmed or otherwise configured to execute instructions according to processes described earlier herein.System Controller

[0079] In some implementations, a controller is part of a system, which may be part of the abovedescribed examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, 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, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency 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.

[0080] 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. Different controllers may be provided for different purposes and these controllers may communicate with one another as needed. For instance, FIG. 4 illustrates certain tasks that may be done by (i) a main controller that controls various aspects of the electroplating process, and (ii) a lift controller that primarily controls the position of the lift.

[0081] 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 examples, 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.

[0082] 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 combinationthereof. 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 ty pe 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.

[0083] Without limitation, example systems may' include a plasma etch chamber or module, 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.

[0084] 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.CONCLUSION

[0085] Although the foregoing examples have been described in some detail for purposes of clanty of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present examples.Accordingly, the present examples are to be considered as illustrative and not restrictive, and the examples are not to be limited to the details given herein.

Claims

CLAIMSWhat is claimed is:1 . A method of electroplating substrates including a first substrate and a second substrate, the method comprising:(a) receiving the first substrate in a substrate support of an electroplating cell, the electroplating cell comprising: a vessel configured to hold electrolyte, a substrate support configured to support one of the substrates during electroplating, and a lift configured to control a position of the substrate support;(b) lowering the first substrate toward a surface of the electrolyte;(c) applying a potential to the first substrate while lowering the first substrate toward the surface of the electrolyte, wherein the potential is applied to the first substrate both (i) before an initial immersion time for the first substrate, and (ii) at the initial immersion time for the first substrate, wherein the initial immersion time for the first substrate is a time at which the first substrate begins contacting the electrolyte;(d) determining the initial immersion time for the first substrate, the initial immersion time for the first substrate corresponding to a time at which a current supplied to the first substrate reaches a threshold current;(e) determining a liquid touch point position for the first substrate, the liquid touch point position for the first substrate corresponding to a position of the lift at the initial immersion time for the first substrate;(f) electroplating the first substrate while the first substrate is immersed in the electrolyte, and then removing the first substrate from the electroplating cell;(g) receiving the second substrate in the substrate support of the electroplating cell; and(h) lowering the second substrate toward the surface of the electrolyte using an entry profile that indicates the second substrate will begin entering the electrolyte at the liquid touch point position for the first substrate determined in (e).

2. The method of claim 1, further comprising repeating the method on additional substrates, wherein each substrate is lowered toward the surface of the electrolyte using an entry' profile that indicates that the substrate will begin entering the electrolyte at the liquid touch point position determined for a previously electroplated substrate.

3. The method of claim 2. wherein a composition of the electrolyte changes over a course of plating the additional substrates, and wherein the liquid touch point position determined in (e) changes in response to the changing composition of the electrolyte.

4. The method of claim 3, wherein the composition of the electrolyte changes with respect to one or more accelerator, suppressor, or leveler.

5. The method of claim 1, wherein the potential applied to the first substrate in (c) is a constant potential.

6. The method of claim 1, wherein both the first substrate and the second substrate are tilted with respect to the surface of the electrolyte as they are lowered toward the electrolyte, and wherein both the first substrate and the second substrate are rotated about an axis as they are lowered toward the electrolyte.

7. The method of claim 6, wherein the entry profile in (h) specifies one or more of (i) a z- speed profile for the second substrate as the second substrate is immersed into the electrolyte, (ii) a tilt profile for the second substrate as the second substrate is immersed into the electrolyte, and / or a rotation speed profile for the second substrate as the second substrate is immersed into the electrolyte.

8. The method of claim 1, wherein the electroplating cell is powered by a power supply, wherein a position of the lift is controlled by a lift controller, and wherein the power supply sends a high speed digital signal to the lift controller when the current supplied to the first substrate reaches the threshold current.

9. The method of claim 8, wherein the lift controller immediately saves an instantaneousposition of the lift upon receipt of the high speed digital signal from the power supply, the instantaneous position of the lift at that time corresponding to the liquid touch point position for the first substrate.

10. The method of claim 1, further comprising calculating an adjusted liquid touch point position based on the liquid touch point position for the first substrate determined in (e) and a liquid touch point position offset, wherein the entry profile for the second substrate indicates that the second substrate will begin entering the electrolyte at the adjusted liquid touch point position.

11. The method of claim 1. further comprising providing the liquid touch point position for the first substrate to a factory’ host.

12. An apparatus for electroplating substrates including a first substrate and a second substrate, the apparatus comprising: a power supply; a vessel configured to hold electrolyte; a substrate support configured to support one of the substrates during electroplating; a lift configured to control a position of the substrate support; and a controller configured to cause:(a) receiving the first substrate in the substrate support,(b) lowering the first substrate toward a surface of the electrolyte.(c) applying a potential to the first substrate while lowering the first substrate toward the surface of the electrolyte, wherein the potential is applied to the first substrate both (i) before an initial immersion time for the first substrate, and (ii) at the initial immersion time for the first substrate, wherein the initial immersion time for the first substrate is a time at which the first substrate begins contacting the electrolyte.(d) determining the initial immersion time for the first substrate, the initial immersion time for the first substrate corresponding to a time at which a current supplied to the firstsubstrate reaches a threshold current,(e) determining a liquid touch point position for the first substrate, the liquid touch point position for the first substrate corresponding to a position of the lift at the initial immersion time for the first substrate;(!) electroplating the first substrate while the first substrate is immersed in the electrolyte, and then removing the first substrate from the vessel;(g) receiving the second substrate in the substrate support; and(h) lowering the second substrate toward the surface of the electrolyte using an entry profile that indicates the second substrate will begin entering the electrolyte at the liquid touch point position for the first substrate determined in (e).

13. The apparatus of claim 12, further comprising a lift controller that controls the position of the lift.

14. The apparatus of claim 13, wherein the power supply sends a high speed digital signal to the lift controller when the current supplied to the first substrate reaches the threshold current.

15. The apparatus of claim 14, wherein the lift controller immediately saves an instantaneous position of the lift upon receipt of the high speed digital signal from the power supply, the instantaneous position of the lift at that time corresponding to the liquid touch point position for the first substrate.

16. The apparatus of claim 12, wherein the controller is further configured to cause repeating (a)-(h) on additional substrates, wherein each substrate is lowered toward the surface of the electrolyte using an entry' profile that indicates that the substrate will begin entering the electrolyte at the liquid touch point position determined for a previously electroplated substrate.

17. The apparatus of claim 16, wherein a composition of the electrolyte changes over a course of plating the additional substrates, and wherein the liquid touch point position determined in (e) changes in response to the changing composition of the electrolyte.

18. The apparatus of claim 17, wherein the composition of the electrolyte changes with respect to one or more accelerator, suppressor, or leveler.

19. The apparatus of claim 12. wherein the potential applied to the first substrate in (c) is a constant potential.

20. A method of dynamically measuring a liquid touch point while electroplating a plurality of substrates including at least a first substrate and a second substrate, the method comprising: (a) while immersing a first substrate in electrolyte in an electroplating cell, measuring a liquid touch point at which the first substrate first begins to contact the electrolyte;(b) electroplating metal onto the first substrate and then removing the first substrate from the electroplating cell;(c) immersing a second substrate in the electrolyte using an entry profile that indicates that the second substrate will begin entering the electrolyte at the liquid touch point measured with respect to the first substrate in (a); and(d) electroplating metal onto the second substrate.

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