TWI906345B - Electrochemical deposition system and residual removal method thereof - Google Patents

Abstract

An electrochemical deposition system configured for electrochemical plating of a substrate includes a chamber, an electrode, a plating cup and a controller. The chamber holds a plating bath. The electrode is disposed in the plating bath. The plating cup includes a contact ring. The contact ring includes contacts. The contacts are immersed in the plating bath. The controller is configured to apply a voltage signal across the contact ring and the electrode to remove residual from the contacts. The voltage signal includes a plating-de-plating waveform. The plating-de-plating waveform includes multiple cycles. Each of the cycles includes a pair of pulses with different polarity.

Description

Electrochemical deposition system and its residue removal method

This invention relates to an electroplating system, and more specifically, to contacts for cleaning an electroplating system.

The prior art description provided herein is intended to provide a general overview of the background of this invention. The achievements of the inventors listed in this application, and embodiments of descriptions that were not deemed prior art at the time of application, within the scope described in this prior art section, are not intentionally or implied to be considered prior art in opposition to this invention.

Electrochemical deposition (ECD) is a process commonly used for metallization in integrated circuit manufacturing. ECD involves immersing a substrate in a plating bath and performing electrochemical deposition of metals to fill recessed patterns on the substrate surface. These recessed patterns include features of various sizes (e.g., vias and channels) and are formed by plasma etching of the substrate's dielectric layer. Prior to ECD, multiple thin film layers are deposited conformally or near-conformally on the substrate. Thin film layers typically include: a barrier layer to prevent metal diffusion into the dielectric material of the substrate; a backing layer to improve adhesion to the barrier layer; and a seed layer, which is formed of the same metal deposited for current conduction across the entire substrate.

During ECD (Enhanced Coding), metal is deposited on the seed layer. Various additives are added to the plating bath to achieve superconducting deposition, thereby filling the feature portions of the recessed pattern without creating any porosity within the feature portions. After filling the feature portions, deposition continues until an overcoat layer with the target overcoat thickness is formed. Following the ECD process, the overcoat layer is first removed using chemical mechanical polishing (CMP), followed by an overpolishing operation to remove the thin top portion of the dielectric material. As a result, the metal-filled feature portions (or recesses) appear as individual metal patterns. The ECD process can be performed iteratively multiple times to create multi-layered metal interconnect feature portions. Metals deposited during ECD treatment can include copper (Cu), cobalt (Co), and zinc (Zn).

An electrochemical deposition system configured for electrochemical plating of a substrate is provided. The electrochemical deposition system 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 contacts. The contacts are immersed in the plating bath. The controller is configured to apply a voltage signal between the contact ring and the electrode to remove residues from the contacts. The voltage signal includes a plating-deplating waveform. The plating-deplating waveform includes multiple cycles. Each of these multiple cycles contains a pair of pulses with different polarities.

Among other features, the electrochemical deposition system further includes a diaphragm disposed within the chamber and between the electrode and the contact ring. The diaphragm separates a first portion of the coating bath from a second portion of the coating bath.

Among other features, a corresponding portion of the residue is removed during each of the multiple cycles. Among other features, the controller is configured to adjust the voltage of one of the pulses before or during a corresponding pulse in the multiple cycles.

Among other features, the controller is configured to adjust the duration of one of the pulses before or during a corresponding pulse in the cycles. Among other features, the controller is configured to adjust the current level of one of the pulses before or during a corresponding pulse in the cycles.

Among other features, the controller is configured to perform the following operations: determine whether a predetermined criterion is met; and based on whether the predetermined criterion is met, continue to apply the voltage signal.

Among other features, the plating-deplating waveform includes an initial deplating pulse preceding the cycles. Among other features, the final deplating pulse of the plating-deplating waveform has an extended duration, such that the duration of the final deplating pulse is longer than the duration of the other deplating pulses of the plating-deplating waveform. Among other features, the controller is configured to perform one or more passive etching operations to further remove residues from the contacts.

Among other features, a method for removing residues from an electrochemical deposition system configured for electrochemical coating of a substrate is provided. The method includes: removing the substrate from a coating cup, wherein the coating cup includes contacts for contacting the substrate; immersing the contacts in a coating bath within a chamber of the electrochemical deposition system; applying a voltage signal between an electrode and the contacts to remove residues from the contacts, wherein the electrode is disposed in the coating bath, wherein the voltage signal includes a coating-decoction waveform, wherein the coating-decoction waveform includes multiple cycles, and wherein each of the cycles includes a pair of pulses with different polarities; and rinsing the contacts with deionized water after applying the voltage signal.

Among other features, a corresponding portion of the residue is removed during each of the plurality of cycles. Among other features, the residue removal method further includes adjusting the voltage of one of the pulses before or during a corresponding phase of each of the cycles.

Among other features, the residue removal method further includes adjusting the duration of one of the pulses before or during a corresponding pulse in the cycles. Among other features, the residue removal method further includes adjusting the current level of one of the pulses before or during a corresponding pulse in the cycles.

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

Among other features, the predetermined criterion includes determining whether a predetermined number of substrates have been processed in the chamber. Among other features, the plating-deplating waveform includes an initial deplating pulse preceding the multiple cycles.

Among other features, the final descaling pulse of the overcoat-descaling waveform has an extended duration, such that the duration of the final descaling pulse is longer than the duration of the other descaling pulses of the overcoat-descaling waveform. Among other features, the residue removal method further includes performing one or more passive etching operations to further remove residue from the contacts.

Further applications of this disclosure will become apparent from the embodiments, the scope of the invention claims, and the drawings. The detailed descriptions and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure.

100: Partial

102: Contact

104: Contact Ring

106: Coated Cup Components

108: Controller

110: Switching circuit

112: Power Source

118: Electroplating bath

120: Cups

122: Cone

123: Chamber

124: Rooftop

125: Chamber wall

126: Pillar

127: Bottom of the chamber

130: Electrode

131: Dashed line

140: Inferior chamber portion

142: Upper chamber portion

144: Diaphragm

146: Diaphragm Frame

150: Entrance

152: Parts

154: Region

156: Channel

160: Spindle

161: Motor

162: Lip seal

163: Actuator Components

164: Conical Seal

165: Top Side Plugin

170: Sensor

172: Robots

200: Partial

202: Coated Cup Components

210:Substrate

212: Contact

214: Cups

220: Coating tank

222: Surface

224: Lip seal

226: Spindle

230: Cone

232: Conical seal

240: Contact Ring

300: Contact Ring

302: Circular Main Body

304: Contact finger

310: Outer side

314: Inner part

330: Partial

334: Residue

400: Operation

402: Operation

404: Operation

406: Operation

408: Operation

410: Operation

412: Operation

414: Operation

414A: Operation

414B: Operation

414C: Operation

414D: Operation

415: Operation

416: Operation

418: Operation

420: Operation

422: Operation

500: Coating - Decoction Waveform

502: Upper part

504: Lower part

510: Initial deplating pulse

512: First plating pulse

This disclosure will be more fully understood from the embodiments and accompanying drawings, wherein: according to this disclosure, Figure 1 is a functional block diagram and cross-sectional view of a portion of the electroplating system, showing the contact between the plating cup and the plating bath; Figure 2 is a cross-sectional view of a portion of the electroplating system, showing the components of the plating cup and its contact with the substrate.

Figure 3A is a top view of the contact ring including the annular main body.

Figure 3B is a top view of a portion of the contact ring of Figure 3A, showing the contact fingers.

Figure 3C is a top view of a portion of the contact finger of Figure 3B with non-metallic residue; Figure 3D is a top view of the contact finger portion of Figure 3C, wherein the non-metallic residue is removed due to the residue removal procedure performed according to this disclosure; Figure 4 shows an exemplary residue removal procedure according to this disclosure; and Figure 5 shows an exemplary plating-deplating waveform according to this disclosure.

In the diagram, component symbols may be reused to distinguish similar and/or identical components.

During ECD processing, electrical contact is established on the outer circumferential edge of the substrate using metal finger-shaped contacts (or pins) of contact rings. These pins are typically made of corrosion-resistant metal alloys or precious metals. The width of the contact area between the pins and the substrate surface can range from several millimeters to less than 1 millimeter. Each contact ring typically has a large number of contact pins (e.g., hundreds) 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 is also immersed in the same plating bath. The anode is typically formed from the same type of metal material deposited on the substrate. A power supply provides current flowing through the anode, plating bath, substrate surface, and contact pins of the contact ring. Metal is deposited on the substrate surface through the electrochemical reduction of metal ions present in the plating bath. The anode is oxidized and provides metal ions to the plating bath. In the sealed contact design, the area on the outer circumferential edge of the substrate (where electrical contact occurs with the contact pin) is sealed using a lip seal to isolate the electrical contacts and the circumferential edge from the plating bath.

The portion of the plating bath that holds 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 inside 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 contact pins or the sealed circumferential edge of the substrate. One requirement of ECD processing is to provide uniformity in the thickness of the deposited metal film. Uniform low-resistance electrical contacts are required along the entire circumference of the substrate to control the uniformity of the plating thickness. To maintain consistent contact at the circumferential edge, the metal contact pins need to be kept clean and free of residue.

Although the contact pins and substrate edges are sealed to prevent interference from the plating bath, droplets may still come into contact with the contact pins during substrate transport. For example, a thin liquid film may be present on the lower surface of the substrate adjacent to 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 bath, the liquid film may be dragged out by the substrate movement and fall as droplets onto the contact pins. These droplets are typically rinsed and diluted in the plating bath using deionized water (DIW).

During the coating process, current flows from the substrate to the contact pins. A decrease in I-R (or power) associated with the high contact resistance at the pin-substrate interface creates a potential difference at the contact pin-substrate interface. In the presence of a liquid, a miniature electrochemical cell is formed at the contact-liquid-substrate interface, with the substrate surface acting as the anode and the contact pins as the cathode. The seed layer on the peripheral edge of the substrate comes into contact with the liquid, dissolves, and redeposits onto the contact pins. As the contact pins dry, the organic additives used in the coating bath also deposit on them. The material deposited on the contact pins is subsequently oxidized by oxygen present in the ambient air. This process creates non-conductive residue on the contact pins. This residue is a mixture of metal oxides and components of the plating bath and has a brown to black appearance. Depending on the substrate and plating bath used, the residue on the contact pins can accumulate significantly and be a thick, easily visible brown to black material. The residue can negatively impact electrical contact with the substrate and reduce plating uniformity. Excessive accumulation can lead to decreased tooling performance and potential damage. The residue may peel off from the contact pins and fall onto the substrate surface, resulting in an increased number of defects. Metal dendrites may form around the contact pin and cause arcing, which can damage the coated cup.

The coated cups are periodically rinsed using a DIW (Distillation Water Bath) and then dried by rotation. Residues on the contact pins are insoluble in water and are not removed during this rinsing process. As a means of automated cleaning, a portion of the coated cup (including the contact rings and other components) can be immersed in the coating bath for soaking and subsequent rinsing. However, experiments have shown that while such immersion processes at least partially dissolve residues, they are very slow and impractical for production tools.

Deplating treatments (including the application of an externally supplied anodic current or potential) can be used to electrochemically dissolve metal deposited on contacts. However, deplating treatments only remove the metallic material deposited on the contacts. Applying such deplating treatments directly to contacts with non-metallic residues, as described above, will not completely dissolve the deposits. This is also true even with prolonged exposure to the supplied anodic current or potential.

At least for the reasons mentioned above, residues are not easily removed by DIW rinsing, immersion in a plating bath, and/or simply by applying an anodic potential for deplating. Residue removal typically requires manual chemical etching followed by prolonged rinsing and immersion. This chemical etching process can be used to remove residues from contact pins. The entire tooling, including the plating cup assembly, is removed from production and stopped for chemical etching. The plating cup assembly is then removed from the tooling so that at least some of its components are subjected to chemical etching. Before etching _, an etching solution is prepared consisting of sulfuric acid ( _H₂SO₄ ) and _peroxide ( _H₂O₂ ) at different concentrations. Examples include concentrations of 1-10% _{each of H₂SO₄} and _H₂O₂ . Next, the clad cup assembly is disassembled to remove the metal contacts. The metal contacts are then immersed in the etching solution to chemically dissolve any residue. Alternatively, the clad cup assembly can be directly etched by placing the entire assembly in the etching solution with the contact pins completely submerged. The former method is typically performed to minimize the amount of etching solution trapped within the clad cup assembly. The etching process takes about 30 minutes, depending on the concentration and temperature of the etching solution.

After etching, thoroughly rinse the contact pins and/or coated cups, then immerse them in a DIW (Distillation Injection Water) for approximately 30 minutes to remove as much etching solution as possible. This rinse-immersion process can be repeated multiple times and is performed until the contact pins are pH neutral, followed by drying with nitrogen ( _N₂ ). Next, assemble the components of the coated cup assembly and reinstall the coated cup assembly back into the tooling. Check the concentricity and eccentricity of the coated cup assembly. Then perform calibration. After component calibration and robot handover, return the tooling to its original position for qualification testing. Qualification testing may include running a blank wafer to check uniformity and whether the defect count meets predetermined requirements.

The chemical etching method described has several significant drawbacks, including the calibration and verification of precision components, a substantial impact on tool availability, and the handling of hazardous chemicals. Chemical etching of a plating tank requires shutting down the entire tooling. The contact etching and rinsing procedures after installing the plating cup assembly, as well as hardware calibration, are time-consuming. Furthermore, after successful hardware calibration, the tool must undergo process verification before it can be returned to production. The need for periodic chemical etching treatments to remove residual buildup can significantly impact tool availability. Additionally, the etching solution is prepared from strong acids and oxidants, both of which are hazardous chemicals. Strict Environmental, Health, and Safety (EHS) protocols must be followed when handling these chemicals. Furthermore, every component exposed to the etching solution must be thoroughly cleaned. Any residual etching solution remaining within the coated cup assembly may accelerate future residue buildup.

The example described herein includes removing residual deposits on contacts by performing a coating-decoration process. The coating-decoration process addresses the problems of the aforementioned chemical etching process and includes providing a coating-decoration waveform to continuously remove non-metallic, non-conductive residues on the contacts. By repeating the coating and decoration cycles of this waveform multiple times, the residues can be completely removed. The coating-decoration waveform is applied by a changing voltage potential between (i) the contact pins of the coating cup and (ii) the opposing electrodes. The opposing electrodes are located in the coating bath. The contact pins are immersed in the coating bath. The coating-decoration process described above has been demonstrated to completely remove thick residues from contact pins. Manual chemical etching of the contacts was not involved. The corresponding tools (which may include multiple coating chambers with corresponding coating cups) are able to maintain high productivity while cleaning individual coating chambers. Compared to chemical etching, the total cleaning time is significantly reduced, and tool availability is improved.

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

The electroplating tank 118 includes a chamber 123 defined by a chamber wall 125 and a chamber bottom 127. The cup 120 is supported by a top plate 124 and a support column 126. The top plate 124 is connectable to a spindle 160. During electrochemical deposition (or plating), a substrate can be placed on the contacts 102 of the cup 120. An exemplary substrate is shown in FIG. 2. FIG. 1 shows the substrate absent and the contacts 102 being cleaned. During cleaning (residue removal), controller 108 generates a voltage signal with a plating-deplating waveform, which is provided via switching circuit 110 and applied between (i) contact 102 and (ii) electrode 130 (referred to as "opposite electrode"). Current can be supplied to electrode 130 when operating in plating mode or to contact 102 when in deplating mode. The voltage signal can be provided via pillar 126 and/or plating cup 120, which may be conductive and/or configured to include conductive elements for supplying current to contact 102 and/or receiving current from contact 102. Electric current flows through electrode 130, the first portion of the first electrolyte or plating bath in the lower chamber portion 140 of chamber 123, the second portion of the second electrolyte or plating bath in the upper chamber portion 142, and contact 102. The second electrolyte in the upper chamber portion 142, when used to clean contact 102, may be referred to as a "plating bath" and/or a "plating-deplating bath." The same bath used for removing residues can be used for substrate deposition.

For example, contact 102 may be formed of precious materials. Contacts may be formed of silver, palladium, cobalt, aluminum, gold, zirconium, zinc, platinum, and/or zinc. As another example, when the metal to be plated is cobalt, the residue may include a mixture of cobalt oxide and organic materials including carbon. The residue may be formed of other plated metals and corresponding materials. The residue covers contact 102 without changing the material composition of contact 102. The plating bath may include a mixture of salts, acids, and additives. The salts include the metal to be plated. For example, if copper is being plated, the plating bath may include copper sulfate ( _CuSO4 ), _sulfuric acid ( _H2SO4 ), and additives. As another example, if cobalt is coated, the coating bath may include cobalt sulfate ( _CoSO4 ), _boric acid ( _H3BO3 ), and additives.

The upper chamber portion 142 of chamber 123 is separated from the lower chamber portion 140 by a diaphragm 144 held by a diaphragm frame 146. In some examples, the diaphragm 144 comprises an ion-permeable membrane. The diaphragm 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 chamber 123 and may be partially formed of the deposited material (e.g., cobalt or copper). For example, the dashed line 131 is shown, and it represents an exemplary filling height of the second electrolyte, also referred to as the immersion depth of the cup 120 and the contact 102.

Depending on the operating mode, each of the first and second electrolytes may comprise an anolyte or a catholyte. The second electrolyte may be supplied through inlet 150 to the upper chamber portion 142 of chamber 123, through vertical holes (not shown) in plate 152 (e.g., a high-resistivity virtual anode (HRVA) plate), and into a region 154 (or a corresponding manifold). Alternatively, the second electrolyte may be supplied to region 154 via channel 156.

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

The cup 120 includes a lip seal 162 and holds a contact 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 seal the substrate against the lip seal 162. The contact ring 104 is located between the upper surface of the lip seal 162 and the lower surface of the substrate. The contact ring 104 provides electrical connection to the substrate during plating. 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 further include a sensor 170 (e.g., a temperature sensor) and a robot 172. The sensor 170 may be located above, within, and/or elsewhere in the chamber 123. Signals from the sensor are received at a controller 108. The controller 108 may perform the operations described herein based on the signals from the sensor 170. For example, during contact cleaning, the coating bath may be maintained at a predetermined temperature (e.g., 18-20°C). The robot 172 may be controlled to place the substrate onto the coating cup 120 and remove the substrate from the coating cup 120. At the start of substrate coating, the cone 122 is raised above the cup 120, and the substrate is placed onto the lip seal 162 by the arm of the robot 172.

Figure 2 shows a portion 200 of an ECD (or electroplating) system configured to operate as a residue removal system. Portion 200 includes a coating cup assembly 202, which may replace and/or be configured similarly to the coating cup assembly 202 of Figure 1. During substrate deposition processing, a substrate 210 may be disposed on a contact 212 of a cup 214. The cup 214 includes an opening through which electrolyte from a coating tank 220 contacts the downward-facing surface (or front/working side) 222 of the substrate 210, where coating occurs. The outer periphery of the substrate 210 is positioned on a lip seal 224 of the cup 214. The spindle 226 presses the cone 230 against the cone seal 232 to hold the substrate 210 in place and seals the substrate 210 against the lip seal 224. A contact ring 240, including a contact element 212 (or contact finger), is located between the upward-facing surface of the lip seal 224 and the downward-facing surface 222 of the substrate 210. The contact ring 240 provides electrical connection to the substrate 210 during coating.

Figures 3A-3D show a contact ring 300 having an annular body 302, wherein the annular body 302 has contact fingers (or pins) 304. The contact ring 300 may replace and/or be configured as either the contact rings 104 and 240 of Figures 1-2. In Figure 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 project radially inward. Contact fingers 304 are not shown in Figure 3A but are shown in Figure 3B. Although the contact ring 300 is shown to include contact fingers with a specific configuration, the contact ring 300 may include contact fingers with different configurations.

Figure 3C shows a portion 330 of the contact finger 304 of Figure 3B, which has non-metallic, non-conductive residue (hereinafter referred to as "residue"). The residue may accumulate on the contact in the form of a dark brown or black colored material. For example, the residue may comprise cobalt oxide (an organic mixture). As shown, the contact finger 304 has a tip with the residue 334. These tips are radially inward of the remaining portion of the contact finger 304. Figure 3D shows a portion 330 of the contact finger 304 of Figure 3C, where the residue has been removed by performing the residue removal procedure disclosed herein. An example of this procedure is shown in Figure 4.

Figure 4 illustrates a residue removal procedure. While the following operations are described primarily with reference to the embodiment of Figure 1, these operations can be easily modified for application to other embodiments of this disclosure. These operations can be performed iteratively. The method may begin at operation 400. In operation 402, the controller 108 determines whether predetermined criteria have been met to perform a plating-deplating process. For example, the controller 108 determines whether the number of substrates processed for the corresponding ECD system is equal to or exceeds a predetermined number of substrates. When the predetermined number is reached, operation 404 is executed. In operation 404, the controller 108 removes the last processed substrate (if not already removed) from the cup 120.

Operations 406, 408, and 410 can be performed in different sequences and/or combined into a single operation. In one embodiment, one or more of operations 406, 408, and 410 are not performed. In operation 406, controller 108 may lower the coating cup assembly 106 onto chamber 123. In operation 408, controller 108 may determine the coating bath concentration for the residue removal procedure and/or obtain the coating bath concentration from memory. Controller 108 may adjust the level and/or concentration of the coating bath based on preset settings. In one embodiment, the coating bath used for cleaning is the same as the coating bath used for the substrate to be removed last. In operation 410, controller 108 immerses at least a portion of the coating cup 120 into the coating bath. This can be accomplished by lowering the coating cup 120 into the coating bath and/or adjusting the liquid level in the coating bath. This operation can be based on the concentration determined in operation 408. Without a substrate, at least the radially inward portion of the coating cup 120 is immersed in the coating bath, as shown in FIG. 1. Contact 102 is brought into direct contact with the coating bath. The coating cup 120 is rotated at a specific speed to promote convection.

In operation 412, controller 108 rotates the coating cup 120 to promote convection, thereby enabling mass transfer of the material to be coated onto the contacts. Rotation agitates the (multiple) electrolyte solutions in chamber 123 and allows the process to continue at the same rate, providing uniform processing continuity.

In operation 414, controller 108 applies a plating-deplating (or voltage) waveform between (i) contact 102 and (ii) electrode 130. The voltage waveform is applied between the plating cup 120 and the opposing electrode 130. The plating cup 120 and the opposing electrode 130 can each operate as either an anode or cathode, depending on whether plating or deplating is being 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 coating-decoration waveform 500 may include an upper portion 502 in which a first voltage (or voltage group) of a first polarity is applied; and a lower portion 504 in which a second voltage (or voltage group) of a second polarity is applied. For example, the first polarity may be positive, and the second voltage polarity may be negative. A positive voltage represents the anode, that is, current flows from the contact 102 through the coating bath to the electrode. A negative voltage represents the cathode, that is, current flows from the electrode 130 through the coating bath to the contact 102.

The upper part 502 is associated with plating, and the lower part 504 is associated with deplating. In the example shown, the upper part 502 includes a set of pulses with pulse widths PD1, PD2, PD3, and PD4. The lower part 504 includes a set of pulses with pulse widths DD1, DD2, DD3, DD4, and DD5.

In the example shown, an initial deplating pulse 510 is included, followed by four plating-deplating cycles, which begin with a first plating pulse 512 and end with a final deplating pulse 514. In one embodiment, no initial deplating pulse 510 is provided, and the procedure begins with plating. Any number of plating-deplating cycles may be included. In one embodiment, 4-10 cycles are included. In one embodiment, a predetermined number of plating-deplating cycles are performed to ensure that no residue remains on the contact 102 at the end of the procedure. The duration and amplitude of each pulse of the upper 502 may be the same or different. The duration and amplitude of each pulse in the lower part 504 can be the same or different. The duration and amplitude can be adjusted based on system parameters, materials, composition, etc. The duration, voltage setpoint, and/or current setpoint can be adjusted during one or more cycles. For example, the duration and amplitude can be based on system temperature, the material type of contact 102, and residues and composition of the plating bath. The duration and amplitude of each pulse in the upper part 502 can differ from the duration and pulse of the lower part 504.

In one embodiment, the coating-decoration process lasts for several minutes; however, the process can last for varying durations. In one embodiment, the width of the coating pulse (or the duration of the electroplating event) is set to deposit a film of a predetermined thickness (e.g., 10 nanometers) on the contact. In another embodiment, the width of the decoration pulse (or the duration of the decoration event) is predetermined and set to ensure that material deposited during the previous coating event is removed during the next subsequent decoration event.

Electrode 130 (which is the original metal electrode used for substrate coating) also serves as a cleaning counterpart. The voltage applied between contact 102 and counterpart electrode 130 is selected such that it is high enough to promote the electrochemical dissolution of any components in the residue, but not so high as to transform the residue into a more difficult-to-remove substance. The voltage depends on the tooling setup and coating bath composition, conductivity, and resistivity.

The following operations can be represented by a plating-deplating waveform, such as the waveform shown in Figure 5.

In operation 414A, the initial deplating operation can be performed as described above. In one embodiment, operation 414A is not performed.

In operation 414B, one of the plating operations related to the voltage waveform is performed. During plating, contact 102 operates as the cathode, while the opposing electrode 130 operates as the anode. Metal is deposited on the contacts.

In operation 414C, one of the deplating operations related to the voltage waveform is performed. Contact 102 operates as the anode, while the opposing electrode 130 operates as the cathode. The metal deposited during the previous plating operation is dissolved. The deplating duration is selected to allow complete dissolution of the metal deposited in the previous plating operation. In one embodiment of cobalt metal deposition (or cobalt plating) on contact 102, the deplating voltage amplitude is set between 0.5 and 3V.

During each cycle, some residues on contact 102 dissolve and/or peel off from contact 102 and subsequently dissolve in the coating bath. For example, for cobalt metal deposition, an average cobalt coating thickness of 3-10 nanometers is deposited, which is sufficient to achieve such a cleaning effect. In one embodiment, the coating-decoration cycle is repeated four times.

The final plating-deplating cycle includes a final deplating operation to completely remove any deposited metal that may remain in areas that are difficult to dissolve, such as narrow cracks. This final deplating operation may take longer than the previous ones.

In operation 414D, controller 108 determines whether to execute another coating-decoration cycle. If yes, operation 414B can be executed. In one embodiment, operation 414D is not executed. After applying a predetermined number of coating-decoration cycles, the coating-decoration operation ends.

In operation 415, controller 108 stops the rotation of the coated cup.

In operation 416, the coated cup 120 is lifted. This may include separating the coated cup 120 from the chamber wall 125 and thereby removing the contact 102 from the coating bath.

In operation 418, at least a portion of the coated cup 120 is rinsed and/or soaked with deionized water (DIW). The coated cup 120 may also be rotated. This includes rinsing the contact 102 with DIW. The coated cup 120 is rinsed with DIW to remove any coating bath solution dragged out in previous operations. In operation 420, the controller 108 determines whether to rinse the coated cup 120 again. If yes, operation 418 is repeated; otherwise, the method may end in operation 422. The coated cup 120 is repeatedly rinsed and soaked with DIW to allow any stagnant bath solution to diffuse out, and the coated cup 120 is rotated to remove the liquid. The coated 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 periods, or in different orders. Furthermore, depending on the implementation and/or the sequence of events, some operations may be omitted or skipped.

The aforementioned coating or decoupling operations can be voltage-controlled or current-controlled. In the voltage-controlled case, the applied voltage corresponds to (i) the potential difference between contact 102 and the opposing electrode 130, or (ii) the potential difference between contact 102 and a reference electrode. The reference electrode may be located in chamber 123 and have a reference voltage potential. No current flows through the reference electrode. When voltage is controlled, the required voltage can be provided and applied. When current is controlled, a required current level can be requested, and the voltage can be determined by controller 108 to provide the required current level.

The relative electrode 130 can be an anode for coating, any auxiliary electrode used in the coating bath, or a dedicated electrode. The relative electrode 130 can be formed of the same material as the deposited metal, or it can be formed of different corrosion-resistant metals and/or alloys.

The duration of the coating and decoupling operations can be time-based or endpoint-based. In a time-based embodiment, the duration is set to a predetermined fixed length. In an endpoint-based embodiment, the endpoint of the operation is detected when (i) the applied current amplitude in voltage-controlled mode drops below a predetermined threshold, or (ii) the applied voltage amplitude in current-controlled mode increases above a predetermined threshold.

The above method can be repeated one or more times and may include one or more additional passive etching operations, which do not involve applying current or voltage. For example, an immersion operation may be performed before or after operation 415. Controller 108 may return to operation 414 or continue to operation 416 after the immersion operation. These operations include immersing the contact 102 in a plating bath for a predetermined period of time. Passive etching operations may be referred to as slow etching operations.

The above cleaning procedure can be implemented as an automated periodic preventative maintenance method and/or performed manually as needed. The controller 108 can schedule the execution of this method after a predetermined number of substrates (e.g., 100-200 substrates) have been treated.

Traditionally, chemical etching using strong acids and oxidants is typically required to remove the buildup of insoluble residues. Conventional techniques involve using deplating to remove metal deposits on the contacts, rather than removing non-conductive residues. The described method achieves synergy by performing plating and deplating operations in each cycle to efficiently remove residues from the contacts.

A single coat-and-decorate operation typically does not adequately remove non-conductive residues from contacts. The described method uses multiple coat-and-decorate cycles to iteratively remove portions of the non-conductive residues until the contacts are completely clean. These repeated operations effectively clean the contacts. Simply extending the duration of either the coat or the decorate operation does not accelerate the contact cleaning process.

The described method can also use the same plating bath used for substrate deposition treatment to clean the contacts, and requires no additional etching chemicals, significantly reducing any potential impact on the environment, health, and safety. The cleaning procedure is performed by immersing at least a portion of the coated cup in the same plating bath used for treatment. Therefore, no additional chemicals are required. No hazardous chemicals are used. Because no strong acids or oxidants are used, the risk of accelerated buildup due to trapped residual chemicals after cleaning is reduced.

In one embodiment, the method may include a controller 108 executing an automation software program. The method can be implemented as an automated program executed on a schedule or on demand. No manual hardware operation or manual manipulation of the tools is involved. No disassembly, assembly, or calibration is required during or after the cleaning method. Therefore, the method provides a simplified and efficient technique for cleaning contacts and removing residues. This method significantly reduces the amount of time and resources required to clean contacts. Consequently, the impact of contact cleaning operations on tool availability is reduced, thereby minimizing tool downtime. The program can be executed on individual plating tanks without interfering with other modules of the tool. There is no need to pull the tools out of production, nor to open them to perform the method. No hardware calibration is required after the cleaning procedure. The entire cleaning process can be completed in a few tens of minutes, a significant reduction compared to the tens of hours required by traditional cleaning methods.

The foregoing description is illustrative in nature and is not intended to limit the scope of this disclosure, its application, or its uses. The broad indications of this disclosure can be implemented in various forms. Therefore, while this disclosure contains specific examples, the true scope of this disclosure should not be so limited, as other variations will become clearer when examining the drawings, specifications, and the following claims. It should be understood that one or more steps of the method can be performed in different orders (or simultaneously) without altering the principles of this disclosure. Furthermore, although each embodiment is described above as having certain features, any one or more of these features described in any embodiment of this disclosure may be implemented in any other embodiment and/or combined with features of any other embodiment (even if such combination is not described in detail). In other words, the embodiments described are not mutually exclusive, and substitutions between one or more embodiments remain within the scope of this disclosure.

The spatial and functional relationships between components (e.g., in modules, circuit components, semiconductor layers, etc.) are described using various terms including “connection,” “joint,” “coupled,” “adjacent,” “next to,” “above,” “over,” “below,” and “positioned.” Unless explicitly stated as “direct,” when describing the relationship between the first and second components in the foregoing disclosure, the relationship may be a direct relationship between the first and second components where no other intermediary components exist, or it may be an indirect relationship between the first and second components where one or more intermediary components (spatial or functional) exist. As used in this article, the phrase "at least one of A, B, and C" should be interpreted as referring to the logic of non-exclusionary OR (A OR B OR C), and should not be interpreted as referring to "at least one of A, at least one of B, and at least one of C".

In some embodiments, the controller is part of a system, which may be a component of the examples described above. This system may include semiconductor processing equipment comprising (multiple) processing tools, (multiple) chambers, (multiple) processing platforms, and/or specific processing elements (wafer davits, gas flow systems, etc.). Such systems may be integrated with electronic devices to control the operation of semiconductor wafers or substrates before, during, and after processing. The electronic devices may be referred to as the "controller," which controls various components or sub-components of (multiple) systems. Depending on the processing requirements and/or system type, the controller program can be designed to control any of the processing disclosed herein, including the transport 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 transport settings, position and operation settings, wafer transfer (into and out of tools connected or bonded to a specific system and other transfer tools, and/or load locks).

Broadly speaking, a controller can be defined as an electronic device comprising many integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operations, initiate cleaning operations, and initiate endpoint measurements. Integrated circuits may include: chips in firmware form 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 can be instructions delivered to the controller or system in the form of different individual settings (or program files) that define operating parameters for performing specific processing (on or on a semiconductor wafer). In some embodiments, the operating parameters may be part of a formulation defined by the process engineer to enable one or more processing steps to be performed during the manufacturing of one or more of the following: coatings, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or substrate grains.

In some embodiments, the controller may be part of a computer, or coupled to a computer that is integrated with, coupled to, or networked to the system, or a combination thereof. For example, the controller may be in all or part of a cloud or factory mainframe computer system that allows remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance metrics from multiple manufacturing operations, change parameters for current processing, set the next processing step after the current processing, or start a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system via a network, which may include a local area network or the Internet. The remote computer may include a user interface that enables access to, or the programming of, parameters and/or settings, and then transmits those parameters and/or settings from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool to which the controller is configured to engage or control. Thus, as described above, the controller may be distributed, for example by including one or more separate controllers that are networked together and operate toward a common purpose (e.g., the processes and controls described herein). An example of a distributed controller for this purpose would be one or more integrated circuits communicating on the chamber and at a remote location (e.g., at the work platform level or as part of a remote computer), in combination to control the process on the chamber.

The example system may include, but is not limited to, the following: plasma etching chambers or modules, deposition chambers or modules, rotary rinsing 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, orbital chambers or modules, and any other semiconductor processing system that may be associated with or used in the fabrication and/or processing of semiconductor wafers.

As described above, depending on the (multiple) processing steps to be performed by the tool, the controller may communicate with one or more of the following in the semiconductor manufacturing plant: other tool circuits or modules, other tool elements, clustered tools, other tool interfaces, nearby tools, adjacent tools, tools distributed throughout the plant, a mainframe computer, another controller, or tools used in material transport that transport wafer containers to and from tool locations and/or loading ports.

400: Operation 402: Operation 404: Operation 406: Operation 408: Operation 410: Operation 412: Operation 414: Operation 414A: Operation 414B: Operation 414C: Operation 414D: Operation 415: Operation 416: Operation 418: Operation 420: Operation 422: Operation

Claims (23)

An electrochemical deposition system configured for electrochemical coating of a substrate, the electrochemical deposition system comprising: a chamber containing a coating bath; an electrode disposed in the coating bath; a coating cup including a contact ring, wherein the contact ring includes contacts, and wherein the contacts are immersed in the coating bath; and A controller configured to apply a voltage signal between the contact ring and the electrode to remove residue from the contacts, wherein the voltage signal includes a plating-deplating waveform, wherein the plating-deplating waveform includes multiple cycles, and wherein each of the multiple cycles includes a pair of pulses with different polarities. The electrochemical deposition system of claim 1 further includes a diaphragm disposed in the chamber between the electrode and the contact ring, and separating the first portion of the coating bath from the second portion of the coating bath. The electrochemical deposition system of claim 1, wherein a corresponding portion of the residue is removed during each of the multiple cycles. The electrochemical deposition system of claim 1, wherein the controller is configured to adjust the voltage of one of the pulses before or during the corresponding pulse in the multiple cycles. The electrochemical deposition system of claim 1, wherein the controller is configured to adjust the duration of one of the pulses before or during the corresponding pulse in the multiple cycles. The electrochemical deposition system of claim 5, wherein the controller is configured to adjust the current level of one of the pulses before or during the corresponding pulse in the multiple cycles. The electrochemical deposition system of claim 1, wherein the controller is configured to perform the following operations: determining whether a predetermined criterion is met; and continuing to apply the voltage signal based on whether the predetermined criterion is met. The electrochemical deposition system of claim 1, wherein the plating-deplating waveform is contained in an initial deplating pulse preceding the complex cycle. As in the electrochemical deposition system of claim 1, the final de-plating pulse of the plating-de-plating waveform has an extended duration, such that the duration of the final de-plating pulse is longer than the duration of the other de-plating pulses of the plating-de-plating waveform. The electrochemical deposition system of claim 1, wherein the controller is configured to perform one or more passive etching operations to further remove residues from the contacts. The electrochemical deposition system of claim 1, wherein the controller is configured to apply the voltage signal including the plating-deplating waveform in the absence of any substrate in the chamber. As in claim 1, the electrochemical deposition system, wherein the controller is configured to: lower the coating cup into the coating bath and raise the level of the coating bath before applying the voltage signal, such that the coating cup is immersed in the coating bath; and apply the voltage signal comprising the coating-decoction waveform while the coating cup is immersed in the coating bath. The electrochemical deposition system of claim 1, wherein the controller is configured to rotate the coating cup while applying the voltage signal including the coating-decoration waveform between the contact ring and the electrode. A method for removing residues from an electrochemical deposition system configured for electrochemical coating of a substrate, the method comprising: removing the substrate from a coating cup, wherein the coating cup includes contacts for contacting the substrate; and immersing the contacts in a coating bath within a chamber of the electrochemical deposition system. A voltage signal is applied between an electrode and the contacts to remove residues from the contacts, wherein the electrode is disposed in the plating bath, wherein the voltage signal includes a plating-deplating waveform, wherein the plating-deplating waveform includes multiple cycles, and wherein each of the multiple cycles includes a pair of pulses with different polarities; and after the voltage signal is applied, the contacts are rinsed with deionized water. As in claim 14, a method for removing residues from an electrochemical deposition system, wherein a corresponding portion of the residue is removed during each of the multiple cycles. The residue removal method for an electrochemical deposition system, as described in claim 14, further includes adjusting the voltage of one of the pulses before or during the corresponding pulses in the multiple cycles. The residue removal method for an electrochemical deposition system, as described in claim 14, further includes adjusting the duration of one of the pulses before or during the corresponding pulses in the multiple cycles. The residue removal method for an electrochemical deposition system, as described in claim 14, further includes adjusting the current level of one of the pulses before or during the corresponding pulses in the multiple cycles. The residue removal method for an electrochemical deposition system, as described in claim 14, further includes: determining whether a predetermined criterion is met; and continuing the residue removal method based on whether the predetermined criterion is met. For example, the residue removal method for an electrochemical deposition system in claim 19, wherein the predetermined criteria include determining whether a predetermined number of substrates have been processed in the chamber. As in claim 14, a method for removing residues from an electrochemical deposition system, wherein the plating-deplating waveform includes an initial deplating pulse preceding the complex cycle. As in claim 14, a method for removing residues from an electrochemical deposition system, wherein the final descaling pulse of the coating-descaling waveform has an extended duration, such that the duration of the final descaling pulse is longer than the duration of the other descaling pulses of the coating-descaling waveform. The residue removal method for an electrochemical deposition system, as described in claim 14, further includes performing one or more passive etching operations to further remove residues from the contacts.