CN116075607A - Contact cleaning based on plating-deplating waveforms for substrate plating systems - Google Patents

Abstract

An electrochemical deposition system configured for electrochemical plating of a substrate includes a chamber, an electrode, and a controller. The chamber contains a plating bath. The electrode is disposed in the plating bath. The plating cup includes a contact ring. The contact ring includes a contact. The contact is immersed in the plating bath. The controller is configured to apply a voltage signal between the contact ring and the electrode to remove residue from the contact. The voltage signal includes a plating-deplating waveform. The plating-deplating waveform comprises a plurality of cycles. Each of the plurality of cycles includes pairs of pulses having different polarities.

Description

Contact cleaning based on plating-deplating waveforms for substrate plating systems

Cross Reference to Related Applications

The present application claims priority from U.S. patent application Ser. No.63/065,634, filed 8/14/2020. The entire disclosures of the above-referenced applications are incorporated herein by reference.

Technical Field

The present invention relates to electroplating systems, and more particularly to cleaning contacts of electroplating systems.

Background

The background description provided herein is for the purpose 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.

Electrochemical deposition (ECD) processes (also known as electroplating or simply plating) are commonly used for metallization in integrated circuit fabrication. The ECD process involves immersing the substrate in a plating bath and electrochemical deposition of metal to fill the pattern of depressions on the substrate surface. The recessed pattern includes features of various sizes (e.g., vias and trenches) and is formed by plasma etching the dielectric layer of the substrate. A plurality of thin film layers are conformally or near conformally deposited on the substrate prior to the ECD process. The film layer typically comprises: a barrier layer for preventing diffusion of metal into the dielectric material of the substrate; a liner layer for improving adhesion to the barrier layer; and a seed layer formed of the same metal as deposited for current conduction across the entire substrate.

During ECD, metal is deposited on the seed layer. Various additives are added to the plating bath to achieve super-conformal deposition to fill the features of the recessed pattern without creating any voids in the features. After filling the features, the deposition process continues until a cap layer having a target cap thickness is formed. After the ECD process, the capping layer is first removed using a Chemical Mechanical Polishing (CMP) process, and then an overpolish operation is performed to remove the thin upper portion of the dielectric material. As a result, the metal-filled features (or recesses) are presented as individual metal patterns. The ECD process may be performed iteratively multiple times to fabricate multiple layers of metal interconnect features. The metals deposited during the ECD process may include copper (Cu), cobalt (Co), zinc (Zn), and the like.

Disclosure of Invention

An electrochemical deposition system configured for electrochemical plating of a substrate is provided. The electrochemical deposition system includes a chamber, an electrode, a plating cup, and a controller. The chamber contains a plating bath. The electrode is disposed in the plating bath. The plating cup includes a contact ring. The contact ring includes a contact. The contact is immersed in the plating bath. The controller is configured to apply a voltage signal between the contact ring and the electrode to remove residue from the contact. The voltage signal includes a plating-deplating waveform. The plating-deplating waveform comprises a plurality of cycles. Each of the plurality of cycles includes pairs of pulses having different polarities.

In other features, the electrochemical deposition system further comprises a diaphragm disposed in the chamber between the electrode and the contact ring. The diaphragm separates a first portion of the plating bath from a second portion of the plating bath.

In other features, a respective portion of the residue is removed during each of the plurality of cycles. In other features, the controller is configured to adjust the voltage of one of the pulses before or during a respective one of the plurality of cycles.

In other features, the controller is configured to adjust the duration of one of the pulses before or during a respective one of the cycles. In other features, the controller is configured to adjust the current level of one of the pulses before or during a respective one of the cycles.

In other features, the controller is configured to: determining whether a predetermined criterion is met; and continuing to apply the voltage signal based on whether the predetermined criterion is met.

In other features, the plating-deplating waveform comprises an initial deplating pulse prior to the cycle. In other features, the last deplating pulse of the plating-deplating waveform has an extended duration such that the last deplating pulse has a longer duration than the other deplating pulses of the plating-deplating waveform. In other features, the controller is configured to perform one or more passive etching operations to further remove residue from the contacts.

In other features, a residue removal method for an electrochemical deposition system configured for electrochemical plating of a substrate is provided. The method comprises the following steps: removing the substrate from a plating cup, wherein the plating cup includes a contact for contacting the substrate; immersing the contact in a plating bath in a chamber of the electrochemical deposition system; applying a voltage signal between an electrode and the contact to remove residue from the contact, wherein the electrode is disposed in the plating bath, wherein the voltage signal comprises a plating-deplating waveform, wherein the plating-deplating waveform comprises a plurality of cycles, and wherein each of the cycles comprises pairs of pulses having different polarities; and after applying the voltage signal, rinsing the contact with deionized water.

In other features, a respective portion of the residue is removed during each of the plurality of cycles. In other features, the residue removal method further comprises: the voltage of one of these pulses is adjusted before or during a respective one of these cycles.

In other features, the residue removal method further comprises: the duration of one of the pulses is adjusted before or during a respective one of the cycles. In other features, the residue removal method further comprises: the current level of one of the pulses is adjusted before or during a respective one of these cycles.

In other features, the residue removal method further comprises: determining whether a predetermined criterion is met; and continuing the residue removal method based on whether the predetermined criterion is met.

In other features, the predetermined criteria includes determining whether a predetermined number of substrates have been processed in the chamber. In other features, the plating-deplating waveform includes an initial deplating pulse prior to the plurality of cycles.

In other features, the last deplating pulse of the plating-deplating waveform has an extended duration such that the last deplating pulse has a longer duration than the other deplating pulses of the plating-deplating waveform. In other features, the residue removal method further comprises: one or more passive etching operations are performed to further remove residues from the contacts.

Further scope of applicability of the present disclosure will become apparent from the detailed description, claims and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram and cross-sectional view of a portion of an electroplating system according to the present disclosure, showing contact of a plating cup with respect to a plating bath;

FIG. 2 is a cross-sectional view of a portion of an electroplating system showing components of a plating cup and contact with a substrate;

FIG. 3A is a top view of a contact ring including an annular body;

FIG. 3B is a top view of a portion of the contact ring of FIG. 3A showing contact fingers;

FIG. 3C is a top view of a portion of the contact finger of FIG. 3B with non-metallic residue;

FIG. 3D is a top view of a portion of the contact finger of FIG. 3C, wherein non-metallic residue is removed as a result of performing a residue removal procedure according to the present disclosure;

FIG. 4 illustrates an exemplary residue removal procedure according to the present disclosure; and

fig. 5 shows an exemplary plating-deplating waveform in accordance with the present disclosure.

In the drawings, reference numbers may be repeated to indicate similar and/or identical elements.

Detailed Description

During the ECD process, electrical contact is made on the outer circumferential edge of the substrate by metal finger contacts (or pins) of the contact ring. These pin members are typically made of corrosion resistant metal alloys or precious metals. The width of the contact area where the pin contacts the substrate surface may range from a few millimeters to less than 1 millimeter. The number of contact pins per contact ring is typically large (e.g., hundreds of pins) to achieve uniform low resistance electrical contact with the substrate surface.

During the ECD (or electroplating) process, the substrate surface is immersed in a plating bath. The anode was also immersed in the same plating bath. The anode is typically formed of the same type of metallic material deposited on the substrate. The power supply supplies current through the anode, the plating bath, the substrate surface, and the contact pins of the contact ring. The metal is deposited on the substrate surface by electrochemical reduction of metal ions present in the plating bath. The anode is oxidized and metal ions are provided to the plating bath. In a sealing contact design, the area on the outer circumferential edge of the substrate where electrical contact is made with the contact pins is sealed with a lip seal to isolate the electrical contacts and circumferential edge from the plating bath.

The portion of the plating bath holding the substrate is designed as an open "cup" with a lip seal (or sealing edge) and may be referred to as a plating cup. The substrate is placed within the cup and the lip seal seals the circumferential edge. Only the surface of the substrate to be plated is exposed to the plating bath. No electrochemical reaction occurs on the sealed circumferential edge of the contact pin or the substrate. The requirement of the ECD process is to provide thickness uniformity of the deposited metal film. A uniform low resistance electrical contact along the entire perimeter of the substrate is required to control plating thickness uniformity. In order to maintain consistent contact over the circumferential edge, the metal contact pins need to remain clean and free of residue formation.

Although the contact pins and substrate edges are sealed to avoid the effects of the plating bath, droplets may reach the contact pins during substrate handling. For example, a thin film of liquid is present on a portion of the downward facing surface of the substrate adjacent the lip seal. This is due to the height difference between the substrate and the lip seal. When the substrate is removed from the plating tank, the liquid film may be pulled out by the substrate movement and land on the contact pins in the form of droplets. Such droplets are typically rinsed and diluted in a plating bath with deionized water (DIW).

During the plating process, current flows from the substrate to the contact pins. Due to the I-R (or power) drop associated with the high contact resistance of the pin-substrate interface, a potential difference is created across the contact pin-substrate interface. In the presence of a liquid, a miniature electrochemical cell is formed by the presence of a contact-liquid-substrate interface, with the substrate surface acting as the anode and the contact pin as the cathode. The seed layer on the peripheral edge of the substrate is in contact with the liquid and dissolves and redeposits on the contact pins. As the contact pin dries, the organic additives used in the plating bath also precipitate onto the contact pin. The material deposited on the contact pin is then oxidized by the oxygen present in the ambient air. This process can create non-conductive residue on the contact pin. The residue is a mixture of metal oxide and components in the plating bath and has a brown to black appearance. Depending on the substrate and plating bath used, residue on the contact pins may accumulate in large amounts and be a thick brown to black material that is readily visible to the naked eye. Residues can negatively impact electrical contact with the substrate and reduce plating uniformity. Excessive build-up can lead to reduced tool performance and potential damage. The residue may peel off from the contact pin and fall onto the surface of the substrate, resulting in an increased number of defects. Metal dendrites (metal dendrites) may form around the contact pins and cause arcing phenomena (arcing) that may damage the plating cup.

The plating cup was periodically rinsed with DIW and then dried by spinning. Residues on the contact pin are insoluble in water and therefore are not removed during this rinsing procedure. As a means of self-cleaning, a portion of the plating cup (which includes the contact ring and other components) may also be immersed in the plating bath for immersion and subsequent rinsing. However, it has been experimentally determined that such soaking procedure, while at least partially dissolving the residue, is very slow and not practical for production tools.

A deplating process (which includes applying an externally supplied anodic current or potential) may be used to electrochemically dissolve the metal deposited on the contact. However, the deplating process only removes metallic material deposited on the contacts. Such deplating treatment is applied directly to the contact with non-metallic residues as described above and does not completely dissolve the build-up. Even if exposed to the supplied anodic current or potential for prolonged periods.

For at least the reasons stated above, the residue is not easily removed by rinsing with DIW, immersing in a plating bath, and/or merely deplating by applying an anodic potential. Removal of the residue typically requires a manual chemical etching process followed by a long rinse and soak. The chemical etching process may be used to remove residues from the contact pins. The entire tool, including the plating cup assembly, is removed from production and shut down for the chemical etching process. The plating cup assemblies are then removed from the tool such that at least some of the plating cup assemblies are capable of undergoing chemical etching. Preparation of sulfuric acid (H) at different concentration levels prior to etching ₂ SO ₄ ) With peroxides (H) ₂ O ₂ ) An etching solution is composed. Exemplary mass concentrations include 1-10% H ₂ SO ₄ And H ₂ O ₂ Each of which is a single-phase alternating current power supply. The plating cup assembly is then disassembled to remove the metal contacts. The metal contact is immersed in an etching solution to chemically dissolve the residue. Alternatively, the plating cup assembly is etched directly by placing the entire plating cup assembly in an etching solution and the contact pin is completely submerged. The former method is typically performed to minimize the amount of etching solution trapped within the plating cup assembly. The length of the etching process is aboutFor 30 minutes, depending on the concentration and temperature of the etching solution.

After etching, the contact pins and/or plating cups are rinsed thoroughly and then immersed in DIW for about 30 minutes to remove the etching solution as much as possible. This rinse-soak procedure can be repeated multiple times and performed until the contact pin is pH neutral and with nitrogen (N ₂ ) Drying is performed. The assembly of the plating cup assembly is then assembled and the plating cup assembly is reinstalled back into the tool. Concentricity and eccentricity of the plating cup assembly were checked. Calibration is then performed. After component calibration and robot delivery operations are performed, the tool is replaced for qualification testing. Qualification testing may include running a blank wafer (blank wafer) to check uniformity and to check whether the number of defects meets a predetermined requirement.

The chemical etching method described has several significant drawbacks, including calibration and verification of precision parts, significant impact on tool availability, and handling of hazardous chemicals. To chemically etch a plating tank, the entire tool needs to be shut down. The contact etching and rinsing procedure after the plating cup assembly is installed and the hardware calibration is time consuming. Also, after successful hardware calibration, the tool needs to pass process verification before the tool can be put back into production. Tool availability may be significantly affected due to the need to periodically perform chemical etching processes to remove residual build-up. Furthermore, etching solutions are prepared from strong acids and oxidizing agents, both of which are hazardous chemicals. Strict environmental, health and safety (EHS) agreements are to be followed in handling such chemicals. In addition, each component exposed to the etching solution needs to be thoroughly cleaned. Any residual etching solution that remains in the plating cup assembly may accelerate future residue accumulation.

Examples set forth herein include removing residual build-up on contacts by performing a plating-deplating process. The plating-deplating process solves the problems of the chemical etching processes described above and includes providing a plating-deplating waveform to continuously remove non-metallic, non-conductive residues on the contacts. By repeating the plating and deplating cycles of this waveform a plurality of times, the residue can be completely removed. The plating-stripping waveform is applied at a varying voltage potential between (i) the contact pin of the plating cup and (ii) the counter electrode. The counter electrode is located in the plating bath. The contact pin is immersed in the plating bath. The plating-deplating process described has been demonstrated to completely remove thick residue from contact pins. No manual chemical etching of the contacts is involved. The corresponding tool (which may include a plurality of plating chambers with respective plating cups) is capable of maintaining high yields during cleaning of the individual plating chambers. The total cleaning time is significantly reduced compared to chemical etching processes and tool availability is improved.

Fig. 1 shows a portion 100 of an electrochemical deposition (ECD) (or electroplating) system configured to operate as a residue removal system to clean contacts (e.g., contact fingers) 102 of a contact ring 104 of a plating cup assembly 106. The contact ring 104 and the contact 102 are shown in fig. 3A-3D. Portion 100 includes a plating cup assembly 106, a controller 108, a switching circuit 110, and a power source 112. Plating cup assembly 106 includes plating cell 118 having cup 120 and cone 122. Although specific components are shown for purposes of discussion, the examples set forth herein are applicable to other types of components, handling equipment, or processing equipment.

Plating cell 118 includes a chamber 123 defined by chamber walls 125 and a chamber bottom 127. Cup 120 is supported by top plate 124 and post 126. The top plate 124 may be connected to the spindle 160. During electrochemical deposition (or plating), a substrate may be placed on the contact 102 of the cup 120. An exemplary substrate is shown in fig. 2. Fig. 1 shows the substrate in the absence and while the contact 102 is being cleaned. During cleaning (residue removal), the controller 108 generates a voltage signal having a plating-deplating waveform that is provided via the switching circuit 110 and applied between (i) the contact 102 and (ii) the electrode 130 (which is referred to as the "counter electrode"). Current may be supplied to the electrode 130 when operating in the plating mode or current may be supplied to the contact 102 when in the deplating mode. The voltage signal may be provided via the posts 126 and/or the plating cup 120, and the posts 126 and/or the plating cup 120 may be electrically conductive and/or formed to include electrically conductive components for providing current to the contact 102 and/or receiving current from the contact 102. An electrical current is passed through electrode 130, a first portion of the first electrolyte or plating bath in lower chamber portion 140 of chamber 123, a second portion of the second electrolyte or plating bath in upper chamber portion 142, and contact 102. The second electrolyte in the upper chamber portion 142 may be referred to as a "plating bath" and/or a "plating-deplating bath" when used to clean the contacts 102. The same bath as used to remove the residue can be used for substrate deposition.

For example, the contact 102 may be formed from a precious material. The contact may be formed of silver, palladium, cobalt, aluminum, gold, zirconium, curium, platinum, and/or zinc. As another example and when the metal to be plated is cobalt, the residue may comprise a mixture of cobalt oxide and an organic material comprising carbon. The residue may be formed from other plating metals and corresponding materials. The residue covers the contact 102 and does not change the material composition of the contact 102. The plating bath may include a mixture of salts, acids, and additives. The salt includes the metal to be plated. For example, if copper is plated, the plating bath may include copper sulfate (CuSO ₄ ) Sulfuric acid (H) ₂ SO ₄ ) And (3) an additive. As another example, if cobalt is plated, the plating bath may include cobalt sulfate (CoSO ₄ ) Boric acid (H) ₃ BO ₃ ) And (3) an additive.

The upper chamber portion 142 of the chamber 123 is separated from the lower chamber portion 140 by a diaphragm 144 held by a diaphragm frame 146. In some examples, the membrane 144 comprises an ion permeable membrane. The membrane 144 may be an ion permeable membrane that allows ions to pass through but separates the first electrolyte from the second electrolyte. The electrode 130 is disposed at the bottom of the chamber 123 and may be formed in part from a deposited material (e.g., cobalt or copper). For example, the figure shows a dashed line 131 and it represents an exemplary fill level of the second electrolyte, also referred to as the immersion depth of the cup 120 and the contact 102.

Each of the first electrolyte and the second electrolyte may include an anolyte or a catholyte, depending on the mode of operation. A second electrolyte may be supplied into the upper chamber portion 142 of chamber 123 via inlet 150, through vertical holes (not shown) in plate 152 (e.g., a High Resistance Virtual Anode (HRVA) plate) and into region 154 (or corresponding manifold). A second electrolyte may also be supplied to region 154 via channel 156.

During use, the cup 120 is lowered to expose the contact 102 (to be plated) to the second electrolyte in the upper chamber portion 142 of the chamber 123. The spindle 160 (which is connected to the cone 122) rotates in one or both directions. The spindle 160 may be raised, lowered, and/or rotated by one or more motors 161 of the actuator assembly 163, and the actuator assembly 163 may be controlled by the controller 108. The spindle 160 may rotate the cup 120.

The cup 120 includes a lip seal 162 and maintains contact with the ring 104. The spindle 160 presses the cone 122 against the cone seal 164 to hold the substrate (not shown in fig. 1) in place and seals the substrate against the lip seal 162. The contact ring 104 is located between an upwardly facing surface of the lip seal 162 and a downwardly facing surface of the substrate. The contact ring 104 provides an electrical connection with the substrate during plating of the substrate. A top side insert 165, which may include a flow ring (not shown), is disposed between the plate 152 and the cup 120. The top side insert 165 may be annular.

The ECD system may also include a sensor 170 (e.g., a temperature sensor) and a robot 172. The sensor 170 may be located on or in the chamber 123 and/or elsewhere. Signals from the sensors are received at the controller 108. The controller 108 may perform the operations described herein based on signals from the sensor 170. For example, the plating bath may be maintained at a predetermined temperature (e.g., 18-20 ℃) during contact cleaning. The robot 172 may be controlled to place substrates on the plating cup 120 and to remove substrates from the plating cup 120. At the start of substrate plating, the cone 122 is raised above the cup 120 and the substrate is placed on the lip seal 162 by the arm of the robot 172.

Fig. 2 shows a portion 200 of an ECD (or electroplating) system configured to operate as a residue removal system. The portion 200 includes a plating cup assembly 202 that may be substituted for the plating cup assembly 202 of fig. 1 and/or configured similarly to the plating cup assembly 202 of fig. 1. The substrate 210 may be disposed on the contacts 212 of the cup 214 during a substrate deposition process. The cup 214 contains an opening through which electrolyte from the plating cell 220 contacts the downward facing surface (or front/working side) 222 of the substrate 210 where plating occurs. The outer periphery of the substrate 210 is seated on the lip seal 224 of the cup 214. Spindle 226 presses cone 230 against cone seal 232 to hold substrate 210 in place and seals substrate 210 against lip seal 224. A contact ring 240 including contacts 212 (or contact fingers) is located between the upwardly facing surface of lip seal 224 and the downwardly facing surface 222 of substrate 210. The contact ring 240 provides an electrical connection to the substrate 210 during plating.

Fig. 3A-3D show a contact ring 300 having an annular body 302, wherein the annular body 302 carries contact fingers (or pins) 304. The contact ring 300 may be substituted and/or configured as any of the contact rings 120, 240 of fig. 1-2. In fig. 3A, the contact ring 300 includes an outer portion 310, and an inner portion 314 extending radially inward from the outer portion 310. The inner portion 314 includes contact fingers 304 that protrude radially inward. The contact fingers 304 are not illustrated in fig. 3A, but are illustrated in fig. 3B. Although the contact ring 300 is shown as including a particular configuration of contact fingers, the contact ring 300 may include a different configuration of contact fingers.

Fig. 3C shows a portion 330 of the contact finger 304 of fig. 3B having non-metallic non-conductive residue (hereinafter "residue"). The residue may accumulate on the contact in the form of dark brown or black colored material. For example, the composition of the residue may include cobalt oxide (organic mixture). As shown, the contact finger 304 has a tip with a residue 334. These tips are radially inward of the rest of the contact fingers 304. Fig. 3D shows a portion 330 of the contact finger 304 of fig. 3C, wherein residue is removed as a result of performing the residue removal procedure disclosed herein. An example of this procedure is shown in fig. 4.

Figure 4 shows the residue removal procedure. Although the following operations are described primarily with respect to the implementation of fig. 1, these operations may be readily modified to apply to other implementations of the present disclosure. These operations may be performed iteratively. The method may begin at operation 400. At operation 402, the controller 108 may determine whether a predetermined criterion has been met to perform a plating-deplating process. For example, the controller 108 may determine whether the number of substrates processed for the corresponding ECD system equals or exceeds a predetermined number of substrates. When the predetermined number is reached, operation 404 is performed. At operation 404, the controller 108 removes the last processed substrate (if not already removed) from the cup 120.

Operations 406, 408, and 410 may be performed in a different order and/or combined into a single operation. In an implementation, one or more of operations 406, 408, and 410 are not performed. At operation 406, the controller 108 may lower the plating cup assembly 106 onto the chamber 123. At operation 408, the controller 108 may determine the plating bath concentration for the residue removal program and/or retrieve the plating bath concentration from memory. The controller 108 may adjust the level of the plating bath and/or its concentration based on predetermined settings. In one implementation, the plating bath used for cleaning is the same as the plating bath used to plate the last removed substrate. At operation 410, the controller 108 immerses at least a portion of the plating cup 120 in the plating bath. This may be accomplished by lowering the plating cup 120 into the plating bath and/or adjusting the level of the plating bath. The operation may be based on the concentration determined in operation 408. At least the radially inner portion of the plating cup 120 is immersed in the plating bath without the substrate, as shown in FIG. 1. The contact 102 is brought into direct contact with the plating bath. The plating cup 120 is rotated at a specific speed to promote convection.

At operation 412, the controller 108 rotates the plating cup 120 to promote convection to mass transfer the material to be plated on the contact. The rotation operation agitates the electrolyte solution in the chamber 123 and allows the process to continue at the same speed and with uniform process continuity performance.

At operation 414, the controller 108 applies a plating-deplating (or voltage) waveform between (i) the contact 102 and (ii) the electrode 130. A voltage waveform is applied between the plating cup 120 and the counter electrode 130. The plating cup 120 and the counter electrode 130 may each operate as an anode or cathode, depending on whether plating or deplating is performed. An exemplary plating-deplating waveform 500 is shown in fig. 5, where U is the voltage potential, t is time, PU is the plating voltage potential, and DU is the deplating voltage potential. The plating-deplating waveform 500 may include: an upper portion 502 in which a first voltage (or set of voltages) having a first polarity is applied; a lower portion 504 in which a second voltage (or set of voltages) having a second polarity is applied. For example, the first polarity may be positive and the second voltage polarity may be negative. Positive voltage means that the anode, i.e., current, flows from the contact 102 to the electrode via the plating bath. Negative voltage means that the cathode, i.e., the current, flows from the electrode 130 to the contact 102 via the plating bath.

The upper portion 502 is associated with plating and the lower portion 504 is associated with deplating. In the example shown, the upper portion 502 includes a set of pulses having pulse widths PD1, PD2, PD3, PD 4. The lower portion 504 includes a set of pulses having pulse widths DD1, DD2, DD3, DD4 and DD 5.

In the example shown, an initial deplating pulse 510 is included, followed by four plating-deplating cycles, beginning with a first plating pulse 512 and ending with a last deplating pulse 514. In one implementation, the initial deplating pulse 510 is not provided and the process begins with plating. Any number of plating-deplating cycles may be included. In one implementation, 4-10 cycles are included. In one implementation, a predetermined number of plating-deplating cycles are performed to ensure that there are no residues on the contacts 102 at the end of the process. The duration and amplitude of each pulse of the upper portion 502 may be the same or different. The duration and amplitude of each pulse of the lower portion 504 may be the same or different. The duration and amplitude may be adjusted based on system parameters, materials, composition, etc. The duration, voltage set point, and/or current set point may be adjusted during one or more cycles. For example, the duration and magnitude may be based on the system temperature, the type of material of the contact 102, and the residue and composition of the plating bath. The duration and amplitude of each pulse of the upper portion 502 may be different from the duration and pulse of the lower portion 504.

In one implementation, the plating-deplating process lasts for several minutes, however, the process may last for a different amount of time. In one implementation, the width of the plating pulse (or the duration of the plating event) is set to deposit a film layer having a predetermined thickness (e.g., 10 nanometers) on the contact. In another implementation, the width of the deplating pulse (or the duration of the deplating event) is predetermined and set to ensure that material deposited during the last plating event is removed during the next subsequent deplating event.

Electrode 130, which is the original metal electrode for substrate plating, also serves as the counter electrode for cleaning. The voltage applied between the contact 102 and the opposing electrode 130 is selected such that the voltage is high enough to promote electrochemical dissolution of any components in the residue, but not so high as to convert the residue into a more difficult to remove substance. The voltage depends on the tool setting and plating bath composition, conductivity, and resistivity.

The following operation may be represented by a plating-deplating waveform, such as the waveform shown in fig. 5.

At operation 414A, an initial deplating operation may be performed as described above. In one implementation, operation 414A is not performed.

At operation 414B, one of the plating operations associated with the voltage waveform is performed. During plating, the contact 102 operates as a cathode and the counter electrode 130 operates as an anode. Metal is deposited on the contacts.

At operation 414C, one of the deplating operations associated with the voltage waveform is performed. The contact 102 operates as an anode and the counter electrode 130 operates as a cathode. The metal deposited during the last plating operation is dissolved. The deplating duration is selected so that the metal deposited in the last plating operation is completely dissolved. In one implementation of cobalt metal deposition (or cobalt plating) of the contact 102, the deplating voltage amplitude is set between 0.5-3V.

During each cycle, some of the residue on the contact 102 dissolves and/or peels off the contact 102 and then dissolves in the plating bath. For example, for cobalt metal deposition, an average cobalt plating thickness of 3-10 nanometers is deposited and is sufficient to induce such cleaning effect. In one implementation, the plating-deplating cycle is repeated 4 times.

The last plating-deplating cycle includes a final deplating operation to completely remove any deposited metal that may remain at difficult-to-dissolve sites (e.g., narrow cracks). The final deplating operation may be longer than the previous deplating operation.

At operation 414D, the controller 108 determines whether to perform another plating-deplating cycle. If so, operation 414B may be performed. In one implementation, operation 414D is not performed. After a predetermined number of plating-deplating cycles are applied, the plating-deplating operation ends.

At operation 415, the controller 108 stops the rotation of the plating cup.

At operation 416, the plating cup 120 is lifted. This may involve separating the plating cup 120 from the chamber wall 125 and thereby removing the contact 102 from the plating bath.

At operation 418, at least a portion of the plating cup 120 is rinsed and/or soaked with deionized water (DIW). The plating cup 120 can also be rotated. This includes rinsing the contact 102 with DIW. The plating cup 120 is rinsed with DIW to remove any plating bath that was pulled out during the previous operation. At operation 420, the controller 108 may determine whether to flush the plating cup 120 again. If so, operation 418 is repeated, otherwise the method may end at operation 422. The plating cup 120 is repeatedly rinsed with DIW, soaked to allow any trapped bath to diffuse out, and the plating cup 120 is rotated to remove the liquid. The plating cup 120 is completely dried in a final spin drying operation.

The above operations are intended as illustrative examples. Depending on the application, these operations may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order. Also, depending on the implementation and/or the sequence of events, no operations may be performed or skipped.

The plating or deplating operations described above may be voltage controlled or current controlled. In the case of a controlled voltage, the applied voltage may correspond to (i) the potential difference between the contact 102 and the counter electrode 130, or (ii) the potential difference between the contact 102 and the reference electrode. The reference electrode may be located in the chamber 123 and have a reference voltage potential. No current passes through the reference electrode. When the voltage is controlled, a desired voltage may be provided and applied. When current is controlled, a desired current level may be required and the voltage may be determined by the controller 108 to provide the desired current level.

The counter electrode 130 may be an anode for plating, any auxiliary electrode used in a plating bath, or a dedicated electrode. The counter electrode 130 may be formed of the same material as the deposited metal material, or may be formed of a different corrosion resistant metal and/or alloy.

The duration of the plating and deplating operations may be time-based or end-point-based. In a time-based implementation, the duration is set to a predetermined fixed length of time. In an end-point based implementation, an end-point of operation is detected when (i) the magnitude of the current applied in the voltage controlled mode drops below a certain predetermined threshold, or (ii) the magnitude of the voltage applied in the current controlled mode increases above a certain predetermined threshold.

The above-described method may be repeated one or more times and may include one or more additional passive etching operations that do not include the application of a current or voltage. For example, the soaking operation may be performed before or after operation 415. The controller 108 may return to operation 414 or proceed to operation 416 after the soaking operation. These operations include immersing the contact 102 in the plating bath for a predetermined period of time. The passive etching operation may be referred to as a slow etching operation.

The above-described cleaning process may be implemented as an automated periodic preventative maintenance method, and/or performed manually as needed. The controller 108 may schedule execution of the method after a predetermined number of substrates (e.g., 100-200 substrates) are subjected to processing.

Traditionally, chemical etching with strong acids and oxidants is often required to remove insoluble residue build-up. Conventional techniques include using a deplating process to remove metal deposits on contacts, rather than removing non-conductive residues. By performing plating and deplating operations in each cycle, the described method achieves synergy to remove residue from the contact in an efficient manner.

A single plating-deplating operation typically does not adequately remove non-conductive residues from the contacts. The described method uses multiple plating-deplating cycles to iteratively remove portions of non-conductive residues until the contacts are completely cleaned. This repeated operation can effectively clean the contact. Extending the plating operation duration alone or the deplating operation duration alone does not accelerate the contact cleaning process.

The described methods may also use the same plating bath for contact cleaning as used for the substrate deposition process and do not require any additional etching chemistry, which may significantly reduce any potential impact on the environment, health, and safety. The cleaning process is performed with at least a portion of the plating cup immersed in the same plating bath used for the treatment. Thus, no additional chemicals are required. No hazardous chemicals are used. Since no strong acid or oxidizing agent is used, the risk of accelerated accumulation due to the capture of residual chemicals after cleaning is reduced.

In one implementation, the method may include the controller 108 executing an automation software program. The method may be implemented as an automated program that is executed on-schedule or on-demand. No manual hardware operations and/or manual manipulation of the tool are involved. No disassembly, assembly, or calibration is required during or after the cleaning method is performed. The method thus provides a simplified and efficient technique for cleaning contacts and removing residue. This approach significantly reduces the amount of time and resources required to clean the contacts. Thus, the impact of contact cleaning operations on tool availability is reduced, thereby minimizing tool downtime. The process can be performed on a single plating tank without disturbing other modules of the tool. There is no need to pull the tool out of production and open the tool to perform the method. Hardware calibration is not required after the cleaning process is performed. The entire cleaning process can be completed in up to or less than tens of minutes, with a significant reduction in time compared to the tens of hours required for conventional cleaning methods.

The preceding description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the appended claims. It should be understood that one or more steps in the method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Furthermore, while each embodiment has been described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure may be implemented in and/or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive and permutations of one or more embodiments with each other remain within the scope of this disclosure.

Various terms are used to describe the spatial and functional relationship between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.), including "connect," join, "" couple, "" adjacent, "" next to, "" top, "" above, "" below, "and" set up. Unless a relationship between first and second elements is expressly described as "directly", such relationship may be a direct relationship where there are no other intermediate elements between the first and second elements but may also be an indirect relationship where there are one or more intermediate elements (spatially or functionally) between the first and second elements. As used herein, the phrase "at least one of A, B and C" should be construed to mean a logic (a OR B OR C) that uses a non-exclusive logical OR (OR), and should not be construed to mean "at least one of a, at least one of B, and at least one of C".

In some implementations, the controller is part of a system, which may be part of the examples described above. Such systems may include semiconductor processing equipment including one or more processing tools, one or more chambers, one or more platforms for processing, and/or specific processing components (wafer pedestal, gas flow system, etc.). These systems may be integrated with electronics for controlling the operation of semiconductor wafers or substrates before, during, and after their processing. The electronics may be referred to as a "controller" that may control various components or sub-components of one or more systems. Depending on the process requirements and/or system type, the controller may be programmed to control any of the processes disclosed herein, including the delivery of process 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, location and operation settings, wafer transfer in and out tools and other transfer tools, and/or load locks connected or interfaced with a particular system.

In a broad sense, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, and the like. An integrated circuit may include a chip in the form of firmware that stores program instructions, a Digital Signal Processor (DSP), a chip defined as an Application Specific Integrated Circuit (ASIC), and/or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions may be instructions sent to the controller in the form of various individual settings (or program files) defining operating parameters for performing a particular process on or with respect to a semiconductor wafer or system. In some embodiments, the operating parameters may be part of a recipe defined by a process engineer to complete one or more processing steps during fabrication of one or more layers, materials, metals, oxides, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

In some implementations, the controller may be part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in a "cloud" or all or a portion of a wafer fab (fab) host system, which may allow remote access to wafer processing. The computer may implement remote access to the system to monitor the current progress of the manufacturing operation, check the history of past manufacturing operations, check trends or performance criteria for multiple manufacturing operations, change parameters of the current process, set process steps to follow the current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe 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 parameters and/or settings to be entered or programmed and then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data specifying parameters for each processing step to be performed during one or more operations. It should be appreciated that the parameters may be specific to the type of process to be performed and the type of tool with which the controller is configured to interface or control. Thus, as described above, the controllers may be distributed, for example, by including one or more discrete controllers that are networked together and work toward a common purpose (e.g., the processes and controls described herein). An example of a distributed controller for such purposes is one or more integrated circuits on a chamber that communicate with one or more integrated circuits on a remote (e.g., at a platform level or as part of a remote computer) that combine to control processes on the chamber.

Example systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etching chambers or modules, physical Vapor Deposition (PVD) chambers or modules, chemical Vapor Deposition (CVD) chambers or modules, atomic Layer Deposition (ALD) chambers or modules, atomic Layer Etching (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the manufacture and/or preparation of semiconductor wafers.

As described above, the controller may be in communication with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, tools located throughout the fab, a host computer, another controller, or tools used in transporting wafer containers to and from tool locations and/or load ports in the semiconductor manufacturing fab, depending on one or more process steps to be performed by the tools.

Claims (20)

1. An electrochemical deposition system configured for electrochemical plating of a substrate, the electrochemical deposition system comprising:

A chamber containing a plating bath;

an electrode disposed in the plating bath;

a plating cup comprising a contact ring, wherein the contact ring comprises a contact, and wherein the contact is immersed in the plating bath; and

a controller configured to apply a voltage signal between the contact ring and the electrode to remove residue from the contact, wherein the voltage signal comprises a plating-deplating waveform, wherein the plating-deplating waveform comprises a plurality of cycles, and wherein each of the plurality of cycles comprises pairs of pulses having different polarities.

2. The electrochemical deposition system of claim 1, further comprising a diaphragm disposed in the chamber between the electrode and the contact ring and separating a first portion of the plating bath from a second portion of the plating bath.

3. The electrochemical deposition system of claim 1, wherein a respective portion of the residue is removed during each of the plurality of cycles.

4. The electrochemical deposition system of claim 1, wherein the controller is configured to adjust a voltage of one of the pulses before or during a respective one of the plurality of cycles.

5. The electrochemical deposition system of claim 1, wherein the controller is configured to adjust a duration of one of the pulses before or during a respective one of the plurality of cycles.

6. The electrochemical deposition system of claim 5, wherein the controller is configured to adjust a current level of one of the pulses before or during a respective one of the plurality of cycles.

7. The electrochemical deposition system of claim 1, wherein the controller is configured to:

determining whether a predetermined criterion is met; and

the voltage signal continues to be applied based on whether the predetermined criterion is met.

8. The electrochemical deposition system of claim 1, wherein the plating-deplating waveform includes an initial deplating pulse prior to the plurality of cycles.

9. The electrochemical deposition system of claim 1, wherein a last deplating pulse of the plating-deplating waveform has an extended duration such that the last deplating pulse has a longer duration than other deplating pulses of the plating-deplating waveform.

10. The electrochemical deposition system of claim 1, wherein the controller is configured to perform one or more passive etching operations to further remove residue from the contacts.

11. A residue removal method for an electrochemical deposition system configured for electrochemical plating of a substrate, the residue removal method comprising:

removing the substrate from a plating cup, wherein the plating cup includes a contact for contacting the substrate;

immersing the contact in a plating bath in a chamber of the electrochemical deposition system;

applying a voltage signal between an electrode and the contact to remove residue from the contact, wherein the electrode is disposed in the plating bath, wherein the voltage signal comprises a plating-deplating waveform, wherein the plating-deplating waveform comprises a plurality of cycles, and wherein each of the plurality of cycles comprises a pair of pulses having different polarities; and

after the voltage signal is applied, the contact is rinsed with deionized water.

12. The residue removal method of claim 11, wherein respective portions of the residue are removed during respective portions of the plurality of cycles.

13. The residue removal method of claim 11, further comprising: the voltage of one of the pulses is adjusted before or during a respective one of the plurality of cycles.

14. The residue removal method of claim 11, further comprising: the duration of one of the pulses is adjusted before or during a respective one of the plurality of cycles.

15. The residue removal method of claim 11, further comprising: the current level of one of the pulses is adjusted before or during a respective one of the plurality of cycles.

16. The residue removal method of claim 11, further comprising:

determining whether a predetermined criterion is met; and

the residue removal method is continued based on whether the predetermined criterion is met.

17. The residue removal method of claim 16, wherein the predetermined criteria includes determining whether a predetermined number of substrates have been processed in the chamber.

18. The residue removal method of claim 11, wherein the plating-deplating waveform includes an initial deplating pulse prior to the plurality of cycles.

19. The residue removal method of claim 11, wherein a last deplating pulse of the plating-deplating waveform has an extended duration such that the last deplating pulse has a longer duration than other deplating pulses of the plating-deplating waveform.

20. The residue removal method of claim 11, further comprising: one or more passive etching operations are performed to further remove residue from the contacts.

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