Patent Application
20250215604
This invention relates to the field of semiconductor electroplating processing technology. Specifically, it involves a device for improving electroplating uniformity in wafer electroplating, a method for improving electroplating uniformity using this device, and electroplating equipment comprising the device.
Wafer electroplating is an essential process in semiconductor chip manufacturing and packaging processes. Metal electroplating process is widely used in integrated circuit manufacturing and wafer packaging interconnections and other applications. Currently, Damascus metal interconnects for integrated circuit chips, advanced packaging like 2.5D/3D integration, fan-in/fan-out packaging and other areas are commonly used in the electroplating process of metal wires and metal contacts.
Currently applied in the semiconductor integrated circuit manufacturing process, the electroplating process primarily involves wafer-level horizontal electroplating. This process deposits metal on the surface of round wafers or specific regions of the wafer surface using electroplating equipment and techniques. The electroplating equipment mainly consists of an electroplating tank 102, an electroplating head, and other mechanical driving devices. The electroplating tank holds the electroplating solution and other chemical agents, while the electroplating head loads the wafer. During the electroplating process, the wafer is clamped by the electroplating head and immersed in the electroplating solution within the electroplating tank. The metal at the bottom of the electroplating tank 102 serves as the anode for electroplating, while the wafer serves as the cathode, establishing an electrical current path through the wafer and the electroplating solution to facilitate an electrochemical reaction.
In this process, controlling the distribution of current across the entire wafer surface is necessary to adjust the electroplating rate in different areas, thereby controlling the thickness of metal deposition. Typically, to achieve better uniformity, the anode metal electrode is segmented into different regions for separate control. Depending on the area covered by each region, the corresponding anode metal electrodes adjust their current density to achieve as uniform a distribution as possible throughout the electroplating tank.
Simultaneously, the electroplating head rotates the wafer within the electroplating solution, further improving current distribution and enhancing electroplating uniformity.
However, existing technology, despite measures such as segmented anodes and wafer rotation to improve current distribution uniformity during electroplating, suffers from limitations. As shown in
Furthermore, in some cases, the bare die chips on the wafer are unevenly distributed, leading to irregular-shaped non-electroplating areas. Regions on the wafer with chip interconnects feature numerous openings in photoresist that conduct electricity and deposit metal during electroplating. In contrast, areas without chip interconnects lack these openings and cannot conduct electricity, resulting in no metal deposition. These differences in conductivity cause varying electrical current intensity and electroplating rates between different areas, ultimately leading to uneven thickness of the plated layer and often creating thick spots or areas on the wafer surface, thereby reducing the reliability of semiconductor devices.
Considering the negative impact of non-electroplating areas such as flat edges 6, notches 5, etc. (for convenience, referred to collectively as “notches” in this patent), on the electroplating process, if these issues are not properly addressed, they will severely limit the effectiveness of electroplating on wafers with notches.
To address the deficiencies in existing technology, the purpose of this invention is to provide a device, method and equipment for improving electroplating uniformity in wafer electroplating. By setting up an electroplating rate adjustment component to specifically regulate the electroplating rate in areas near the wafer notches, this invention resolves the current challenges of uniformity control in the wafer electroplating process of semiconductor manufacturing. This improvement helps enhance the yield of wafers and increases the economic efficiency of production.
To achieve the above objectives, this invention adopts the following technical solutions:
According to the first aspect of the present invention, a device for improving electroplating uniformity in wafer electroplating is provided, comprising an electroplating component and an electroplating rate adjustment component;
In this technical solution, by setting the electroplating rate adjustment component, when the switching device in the connection path of the auxiliary electrodes is closed, the auxiliary electrodes and the negative pole of the power supply are in an electrically conductive state. This adds a current path between the anode metal, the electroplating solution, the auxiliary electrodes, and the negative pole of the power supply to the existing current circuit between the anode metal, the electroplating solution, the wafer surface, and the negative pole of the power supply. This diversion of current on the wafer surface controls the current distribution on the wafer surface, adjusting the local electroplating rate on the wafer and resolving the current challenge of controlling electroplating uniformity in the electroplating process. This solution improves the yield of wafers and increases economic efficiency in production. It should be noted that in this technical solution, the term “notch” is a general term for non-electroplating areas such as wafer notches and flat edges.
Further, the auxiliary electrode assembly further includes a circuit resistor assembly, which is connected in series with the auxiliary electrodes; the circuit resistor assembly comprises one or more resistor units, each of which includes one or more resistors;
In this technical solution, the circuit resistor assembly connected in series with the auxiliary electrodes can be used to adjust the current flowing through the auxiliary electrodes, thereby better meeting the needs of the user.
Further, the auxiliary electrode assembly further includes a support ring structure, which is placed in the electroplating tank; this structure comprises a support ring body, a support ring control assembly, and a circuit access assembly; the auxiliary electrodes are fixedly connected to the support ring body; the support ring control assembly is used for controlling the support ring body to drive the auxiliary electrodes to raise and lower and/or to rotate the auxiliary electrode in the electroplating tank, bringing the auxiliary electrodes closer to or farther from the wafer notch; the circuit access assembly is connected to the auxiliary electrodes to integrate them into the circuit, controlled by the switching device; the support ring body is made of insulating material.
In this technical solution, a support ring structure is added to the electroplating rate adjustment component. The support ring structure can support and move the auxiliary electrodes up and down and/or rotate them in the electroplating tank. With the auxiliary electrodes integrated into the circuit, the distance between the auxiliary electrodes and the wafer notch can be actively adjusted, specifically regulating the electroplating rate on the wafer surface near the notch. The range and degree of this influence can be controlled by selecting the activation timing and the movement position of the auxiliary electrodes driven by the support ring structure. This solution addresses the current challenge of uniformity control in the wafer electroplating process of semiconductor manufacturing, helping to improve wafer yield and increase production efficiency.
Further, the support ring control assembly can control the support ring body to move the auxiliary electrodes up and down in the electroplating tank; the support ring control assembly consists of one or more screw-nut structures, which include a screw and a nut; the support ring body is provided with a corresponding number of screw through-holes to allow the screw to pass through; the screw is inserted into the screw through-holes, and the nut is positioned on the lower surface of the support ring body to support it, allowing the support ring body to move up and down along the screw with the nut's support;
In this technical solution, the support ring structure can adjust the distance between the auxiliary electrodes and the wafer notch in the vertical direction, allowing controlled adjustment of the electroplating rate on the wafer surface by the auxiliary electrodes.
Further, the support ring control assembly can control the support ring body to move the auxiliary electrodes up and down and rotate around the axis in the electroplating tank; the support ring structure is a magnetic levitation support ring, and the support ring control assembly includes multiple permanent magnets embedded in the support ring body and AC coils respectively arranged at the bottom and side walls of the electroplating tank; the permanent magnets are evenly distributed around the center of the support ring body, with adjacent permanent magnets having opposite polarities; the AC coils on the side walls of the electroplating tank correspond to the permanent magnets in the support ring body, controlling the rotation of the support ring body; the AC coils at the bottom of the electroplating tank correspond to the permanent magnets in the support ring body, controlling the vertical movement of the support ring body; the AC coils are connected to the control module, which controls the direction, magnitude, sequence changes, and duration of the current in the AC coils.
In this technical solution, the support ring structure is a magnetic levitation support ring that can rotate synchronously or asynchronously with the auxiliary electrodes. This allows the distance between each auxiliary electrode and the wafer notch to be dynamically adjusted both horizontally and vertically. Consequently, the diversion current can be controlled on the wafer to compensate for the differentiated electric field effects on the wafer edge, thereby adjusting the electroplating rate.
Further, the circuit access assembly of the magnetic levitation support ring includes a conductive rod and a surrounding rail; the conductive rod comprises a connection end and a contact end; the connection end is connected to the auxiliary electrode, while the contact end connects to the surrounding rail; the surrounding rail is arranged around the exterior of the electroplating tank and has at least one groove track; the number of groove tracks corresponds to the number of auxiliary electrodes, and they are insulated from each other; each groove track contains a conductive metal ring band; the contact end of the conductive rod includes a preloaded spring and a conductive ball; the conductive ball is pressed against the groove track on the surrounding rail by the expansion force of the preloaded spring in its balanced state, forming electrical contact with the metal ring band to conduct current; a fixed wire is connected to the bottom of each metal ring band in the groove track to conduct the current externally; these fixed wires connect to external circuits, allowing each auxiliary electrode to be connected to its respective circuit;
In this technical solution, when the auxiliary electrode rotates with the support ring structure, to avoid the rotation of the auxiliary electrode causing the connected circuit wires of the resistor assembly to rotate and thereby leading to wire entanglement and interference, the solution includes a conductive rod connected to the auxiliary electrode and a surrounding rail. This design allows the auxiliary electrode to roll on the metal ring band of the surrounding rail via the conductive ball, while the bottom of each track's metal ring band is connected to a fixed wire that leads to an external circuit. This setup ensures that the rotation of the auxiliary electrode does not interfere with the external circuit wires while guiding the current to the external circuit.
Further, the side walls of the groove tracks on the surrounding rail are made of insulating material; when the number of groove tracks on the surrounding rail is greater than one, the metal ring bands in the groove tracks are insulated from each other and staggered vertically; the number of groove tracks is the same as the number of auxiliary electrodes, with each auxiliary electrode corresponding to a specific groove track.
In this technical solution, each rail is insulated from the others to prevent contact short circuits between each independent parallel circuit that includes the auxiliary electrodes. Additionally, the vertical heights of the metal ring bands are staggered to prevent interference between the fixed wires leading to the external circuit at the bottom of the metal ring bands and the conductive rods during the rotation of the conductive rods.
Further, each auxiliary electrode is equipped with an auxiliary electrode lead at one end, which is positioned within the support ring body and extended outside the electroplating tank.
In this technical solution, by setting an auxiliary electrode lead at one end of each auxiliary electrode and embedding it into the support ring body, and then leading it out of the electroplating tank through an externally insulated conductor rod, it is possible to reduce factors such as short-circuiting and corrosion between the auxiliary electrodes.
Further, the electroplating rate adjustment component includes one or more switch triggering devices, which are used to transmit signals to the control module for opening or closing the switching device; the switch triggering device comprises a signal recognition structure and a laser signal transceiver; the signal recognition structure reflects the signal emitted by the laser signal transceiver back to it, and the laser signal transceiver receives the reflected signal, sending a signal to the control module to open or close the switching device.
Further, the submerged portion of the auxiliary electrode in the electroplating solution is cylindrical or fan-shaped; the auxiliary electrode is made of copper, or specified metals compatible with the components of the electroplating solution, or copper coated with specified metals on its surface.
In this technical solution, when the auxiliary electrode is fully immersed in the electroplating solution, its overall shape is cylindrical or fan-shaped. When partially immersed, the submerged portion maintains a cylindrical or fan-shaped shape. Typically, the main material of the auxiliary electrode is copper, but users can also replace it with other metals compatible with the electroplating solution or copper coated with other specified metals.
Further, the number of electroplating rate adjustment components is one or more; when multiple electroplating rate adjustment components are used, the auxiliary electrodes contained in each are evenly distributed within the electroplating tank.
In this technical solution, users can choose to install multiple electroplating rate adjustment components to control the electroplating rate near the notches, ensuring uniformity of the electroplating layer around the notched areas and optimizing overall electroplating uniformity on the wafer. The number of electroplating rate adjustment components can be determined based on the actual arc length proportion of the notches (for example, notch arc length or flat edge*⅓=number of electroplating rate adjustment components).
According to the second aspect of the present invention, a method for improving electroplating uniformity in wafer electroplating is provided, using any of the above-described devices for improving electroplating uniformity in wafer electroplating, comprising the following steps:
In this technical solution, by setting the electroplating rate adjustment component, when the notch of the wafer approaches the auxiliary electrode, the switching device on the connection path where the auxiliary electrode is located is closed. This ensures electrical conduction between the auxiliary electrode and the negative pole of the power supply, thereby adding a pathway in the current circuit between the anode metal, electroplating solution, wafer surface, cathode metal electrode, auxiliary electrode, and negative pole of the power supply. This diversion of current on the wafer surface achieves control over the distribution of current on the wafer surface during the electroplating process, thereby improving the uniformity of wafer electroplating. It should be noted that the phrase “alternatively, after a certain number of wafer rotation cycles” does not require a uniform number of cycles. It means that the switching device can be controlled after different numbers of rotation cycles to adaptively adjust the electroplating rate around the wafer notch according to actual needs.
Further, when the auxiliary electrode is in series with the circuit resistor assembly and the circuit resistor assembly comprises multiple resistors, step S20 further includes: select the resistor combination of the circuit resistor assembly to adjust the electroplating rate around the wafer notch.
In this technical solution, the current flowing through the auxiliary electrode can be adjusted by the circuit resistor assembly in series with it. Each time the switch device on the connection path where the auxiliary electrode is located is closed, the resistance value of the circuit resistor assembly can be independently adjusted according to actual needs (primarily achieved by selecting different resistor combinations within the circuit resistor assembly). This allows different current levels to be obtained at different stages of electroplating, thereby adjusting the electroplating rate around the wafer notch or flat edge region accordingly.
Further, step S20 further includes: control, via the control module, any combination of the following parameters of the connection path where the auxiliary electrode is located: closure time of the switching device, energization interval, pulsation frequency, duty cycle, and resistance value of the circuit resistor assembly.
In this technical solution, through software settings of the control module, when the wafer's notch approaches, passes by, or moves away from the auxiliary electrode during rotation, the above parameters of the connection path where the auxiliary electrode is located can be controlled as needed. This targeted control aims to enhance the uniformity of the wafer's electroplating layer. Specifically, controlling the resistance value of the circuit resistor assembly involves selecting different resistor combinations within the circuit resistor assembly based on the required current for different process steps (where the circuit resistor assembly comprises multiple resistors).
Further, when the electroplating rate adjustment assembly includes a support ring structure, step S20 further includes: during the period when the switching device is closed, control the support ring structure to move up or rotate within the electroplating tank, thereby adjust the proximity of the auxiliary electrode to or away from the wafer notch, further regulate the electroplating rate.
According to the third aspect of the present invention, there is provided an equipment for improving electroplating uniformity in wafer electroplating, comprising any one of the devices described above for improving electroplating uniformity in wafer electroplating.
In comparison with the prior art, the present invention offers the following beneficial effects:
Various exemplary embodiments are described herein by way of example in conjunction with the following Figures, wherein:
To clarify the purpose, technical solution, and advantages of the embodiments described herein, the following detailed description of the embodiments provided in the accompanying drawings is presented. It is understood that the described embodiments are part of this application, and not all possible embodiments are depicted. Components shown and described in the drawings can be arranged and designed in various configurations.
Therefore, the detailed description of the embodiments provided in the drawings is not intended to limit the scope of the claims of this application, but only to represent selected embodiments thereof. All other embodiments obtained by those skilled in the art without creative labor based on the embodiments disclosed herein are within the scope of protection of this application.
It should be noted that similar numerals and letters in the following drawings represent similar elements. Therefore, once an element is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. Additionally, all directional indications (such as up, down, left, right, front, rear, bottom, etc.) used in this application are for explaining the relative positional relationships and movements of the components in a specific orientation (as shown in the drawings). If this specific orientation changes, the directional indications also change Accordingly. Furthermore, descriptions involving “first,” “second,” etc., are used for descriptive purposes only and should not be construed to indicate or imply relative importance or the quantity of the indicated technical features.
As shown in
Specifically, the electroplating component 1 comprises electroplating head 101, electroplating tank 102, anode metal 103 and power supply 104. The electroplating head 101 is used to hold and rotate wafer 105, while electroplating tank 102 contains the electroplating solution. Anode metal 103 is immersed in the electroplating solution within the electroplating tank 102 during electroplating. The positive pole of power supply 104 connects to anode metal 103, and the negative pole connects to the electroplating head 101. Upon activation of power supply 104, a current path forms for electrochemical reactions between the wafer 105 to be plated and the electroplating solution, depositing metal ions from the electroplating solution onto the surface of the wafer 105.
The electroplating rate adjustment component 2 includes an auxiliary electrode 201 and a switching device 202. The auxiliary electrode 201 is set in a designated area within the electroplating tank 102 and is fully or partially immersed in the electroplating solution during electroplating. The auxiliary electrode 201 is electrically connected to the negative pole of the power supply 104. The switching device 202 is positioned on the connection path of the auxiliary electrode 201. During the electroplating process, wafer 105 rotates under the drive of the electroplating head 101. When the notch of wafer 105 rotates to approach or slightly move away from the designated area where the auxiliary electrode 201 is located, the switching device 202 can be closed to adjust the electroplating rate around the notch of wafer 105.
As shown in
During the electroplating process, the electroplating tank 102 holds the electroplating solution, and the electroplating head 101 holds the wafer 105 to position it at the wafer electroplating position. At the same time, the electroplating head 101 rotates the wafer 105 at the wafer electroplating position to enhance electroplating uniformity. As shown in
During the period when the notch of the wafer 105 is approaching the auxiliary electrode 201 to slightly moving away from the auxiliary electrode 201, control can be applied to the switching device 202, such as setting one or more closure times for the switching device 202. When the switching device 202 is in the closed state, the auxiliary electrode 201 and the negative pole are electrically connected. This forms two circuits within the device: the first circuit (the wafer electroplating circuit) formed between the anode metal 103, the electroplating solution, the surface of the wafer 105, and the negative pole, and the second circuit (the auxiliary electrode circuit) formed between the anode metal 103, the electroplating solution, the auxiliary electrode 201, and the negative pole of the power supply 104. The second circuit diverts some of the current provided to the notch area of the wafer 105 from the first circuit, controlling the current distribution on the surface of the wafer 105 and thereby adjusting the electroplating rate around the notch of the wafer 105.
It should be noted that achieving the technical effect of this device does not require the switching device 202 to be closed during each rotation cycle of the wafer 105. The user can set the switching device 202 to close after a certain number of rotation cycles as needed, intermittently adjusting the electroplating rate around the notch of the wafer 105.
Furthermore, as shown in
Additionally, the electroplating rate adjustment assembly 2 also includes a control module. The control module is used to control one or more parameters in the circuit path of the auxiliary electrode 201 during the electroplating process, including the closing time of the switching device 202, the power-on interval, the pulse frequency, the duty cycle, and the resistance value of the circuit resistor assembly 8, to precisely adjust the electroplating rate around the notch of the wafer 105 for a specified duration. The specific usage method can be as follows: by setting the control module, the closing time of the switching device 202 in the circuit path of the auxiliary electrode 201 can be controlled during the three stages when the notch of the wafer 105 approaches the auxiliary electrode 201, passes the auxiliary electrode 201, and slightly moves away from the auxiliary electrode 201 during rotation. Furthermore, it can be set to perform the same closing operation each time it passes or to perform the same closing operation after a certain number of rotations, or to perform different closing operations at different rotation counts. Moreover, by controlling the series-connected circuit resistor assembly 8, the total current flowing through the auxiliary electrode 201 during each closing can be controlled.
In terms of the design of the auxiliary electrode 201, its overall shape is cylindrical or fan-shaped. When the auxiliary electrode 201 is only partially immersed in the electroplating solution, the immersed portion of the auxiliary electrode 201 can also be cylindrical or fan-shaped. Generally, the main material of the auxiliary electrode 201 is copper. However, users can replace it with other metals based on the composition of the electroplating solution or choose a material with a copper main body coated with another metal. As for the switching device 202 in the circuit path of the auxiliary electrode 201, it can be a solid-state relay. The opening and closing of the solid-state relay control the electrical connection between the auxiliary electrode 201 and the negative pole of the power supply 104.
The device for improving electroplating uniformity in wafer electroplating provided by this embodiment sets up an auxiliary electrode 201 in a specified area within the electroplating tank 102, at a certain distance from the rotating electroplating head 101. When the auxiliary electrode 201 and the wafer 105 held by the electroplating head 101 are immersed in the electroplating tank 102 and start rotating, the height of the auxiliary electrode 201 is at the same level or somewhere between this level and the anode metal 103. The auxiliary electrode 201 is either fully or partially immersed in the electroplating solution. The auxiliary electrode 201 is directly connected to the cathode potential of the electroplating head 101 or connected through a series circuit resistor assembly 8, with a switching device 202 set on the circuit path. Clearly, by installing the device proposed in this application, an additional circuit is formed in the current path between the anode metal 103, the electroplating solution, the wafer 105 surface, and the negative pole, specifically through the anode metal 103, the electroplating solution, the auxiliary electrode 201, the circuit resistor assembly 8, and the power supply's negative pole (the auxiliary electrode circuit). By diverting some current from the surface of the wafer 105, the device controls the current distribution on the wafer 105 surface, thereby regulating the local electroplating rate on the wafer 105 and improving the uniformity of the wafer electroplating process.
The reason for connecting the auxiliary electrode 201 to the negative pole of the power supply 104 in this embodiment is as follows: as shown in
However, if the auxiliary electrode 201 (including the series circuit resistor assembly 8 if the auxiliary electrode 201 is in series with it) is connected to the negative pole of the power supply (i.e., the dashed line is disconnected), then the potential of the wafer metal electrode will not be simply 1 ampere multiplied by the resistance value between the negative pole of the power supply and the negative pole of the power supply. Consequently, the current from the wafer metal electrode to the negative pole of the power supply changes, achieving the adjustment effect.
Based on the first embodiment, this embodiment further designs the circuit resistor assembly 8 in the electroplating rate adjustment component 2. In this embodiment, the circuit resistor assembly 8 includes one or more resistor units, with each resistor unit comprising one or more resistors. When a resistor unit includes multiple resistors, these resistors are connected in series and/or parallel. The user can, according to electroplating needs, connect one or more resistor units into the circuit of the auxiliary electrode 201 and, on this basis, incorporate one or more resistors from the resistor unit.
Below are examples from
If switch a and switch b are both open, resistor R1 is connected.
If switch a is closed and switch b is open, resistors R1 and R2 are connected in parallel.
If switch a (whether open or closed) and switch b is closed, where switch b′s circuit resistance is zero, then the current mainly passes through here.
Users can dynamically adjust the current provided to the vicinity of the gap in wafer 105 by controlling the opening and closing states of switches a and b through the control module, as well as adjusting the duration of their opening and closing. This adjustment aims to control the distribution of current on the surface of wafer 105 effectively.
When the master switch Ketoxal is at point e, the circuit is open.
When the master switch K_total is at point d:
If the resistor switch is closed to point a, resistor R1 is connected.
If the resistor switch is closed to point b, resistors R2 and R3 are connected in parallel.
If the resistor switch is closed to point c in between ab, no resistor is connected.
When the master switch K_total is at point f:
If the resistor switch is closed to point a′, resistor R1′ is connected.
If the resistor switch is closed to point b′, resistors R2′ and R3′ are connected in parallel.
If the resistor switch is closed to point c′ in between a′b′, no resistor is connected.
Users can dynamically adjust the current supplied to the periphery of the wafer 105 by controlling the opening and closing states of each switch and the duration of these states through a control module, thereby achieving control over the distribution of surface currents on wafer 105.
This embodiment provides a device for improving the electroplating uniformity in wafer electroplating, which shares a similar structure to the device described in the first embodiment and incorporates the circuit resistor assembly 8 design from the second embodiment. The distinguishing feature here is that this embodiment includes three electroplating rate adjustment components 2, as shown in
During the electroplating process, when wafer 105 is in a rotating state, its notch undergoes four stages relative to each auxiliary electrode 201: approaching, passing, slightly moving away, and moving far away. During the period when the notch of wafer 105 is approaching or slightly moving away from an auxiliary electrode 201, the control module can manage the operation of the switching device 202. By setting one or more closure times for the switching device 202, when the switching device 202 is closed, electrical conductivity is established between the auxiliary electrode 201 and the negative pole. This setup enables adjustments to the electroplating rate around the notch of wafer 105.
It should be emphasized that although the present embodiment is provided with three auxiliary electrodes, it does not require that the switching device 202 on the connecting path where the three auxiliary electrodes 201 are located be in the state of being closed sequentially during a certain rotation cycle of the wafer. Users can choose when to close the switching device 202 on the connection paths of the auxiliary electrodes 201, which auxiliary electrode 201's switch to close, how many of the auxiliary electrode 201's switches to close, how often to close the switches on the connection paths of the auxiliary electrodes 201, and similar parameters, all based on their actual needs.
In addition, in other embodiments, the number of electroplating rate adjustment components 2 can be set based on the arc length ratio of the gap on wafer 105. For example, the number of electroplating rate adjustment components 2 can be configured to equal the gap arc length*⅓. In another embodiment, the device includes 6 electroplating rate adjustment components 2, as shown in
This embodiment provides a device for improving the electroplating uniformity in wafer electroplating, which has substantially the same structure as the device provided in embodiment 3, with the difference that said electroplating rate adjustment component 2 also comprises a support ring structure. In this embodiment, the three auxiliary electrodes 201 are not evenly distributed along the inner sidewall of electroplating tank 102, but are instead mounted on the support ring structure. In this embodiment, the support ring structure, auxiliary electrodes 201 and circuit resistor assembly 8 together form the auxiliary electrode assembly.
In this embodiment, the electroplating rate adjustment component 2 comprises an auxiliary electrode assembly, a switching device 202 and a control module. The auxiliary electrode assembly includes auxiliary electrodes 201, a circuit resistor assembly 8, and a support ring structure. The support ring structure consists of a support ring body 204, a support ring control assembly, and a circuit access assembly. The auxiliary electrode 201 is fixedly attached to the support ring body 204. The support ring control assembly is used to control the support ring body 204 to move the auxiliary electrode 201 closer to or further away from the gap of the wafer in the electroplating tank 102. The circuit access component is connected to the auxiliary electrode 201 to integrate it into the circuit. The support ring body 204 is made of insulating material.
In this embodiment, as shown in
The liftable support ring comprises a support ring body 204 and one or symmetrically arranged multiple screw-nut structures set on the support ring body 204, consisting of screw 205a and nut 205b. Both the support ring body 204 and screw-nut structures are made of high-density polyethylene (HDPE). Uniformly distributed on the support ring body 204 are screw holes corresponding in number to the screw-nut structures, illustrated here with three as an example. Screw 205a inserts into the screw holes on the support ring body 204, securing it, while nut 205b is fixed beneath the support ring body 204 to support it.
One end of auxiliary electrode 201 is fixed onto support ring body 204, with its other end either coupled with screw 205a on the upper surface of support ring body 204 or fixed to nut 205b on the lower surface of support ring body 204, allowing one or multiple stacked auxiliary electrodes 201 to be securely mounted on screw 205a and nut 205b. By manually or mechanically synchronizing the rotation of screw 205a, nut 205b, and the auxiliary electrode 201 on the same horizontal plane, the distance between support ring body 204 and auxiliary electrode 201 can be adjusted relative to the surface of wafer 105 during electroplating. The vertical movement of auxiliary electrode 201 must ensure that it is partially or fully immersed in the electroplating solution.
To minimize short-circuiting between auxiliary electrodes 201 and corrosion, one end of auxiliary electrode 201 is connected to auxiliary electrode lead 207, a single multi-core wire passing through and securely embedded in support ring body 204, extending to the outside of electroplating tank 102. The other end of each auxiliary electrode 201 is connected via electroplating adjustment lead 208 to circuit resistor assembly 8 and is linked to negative pole of power supply 104.
Each auxiliary electrode 201 has its own independent circuit arrangement. As shown in the circuit diagrams in
Each auxiliary electrode 201 is equipped with one or more switching devices 202 between itself and the negative pole of power supply 104, used to control whether the auxiliary electrode 201 is connected to or disconnected from the circuit. Additionally, between each auxiliary electrode 201 and the negative pole of power supply 104, there is also a circuit resistor assembly 8 as described in the second embodiment.
When the switching device 202 is open, current flows from the positive pole of power supply 104, sequentially passing through the bottom anode metal 103 of the electroplating tank 102, the electroplating solution, wafer 105, and the electroplating head 101, and finally returning to the negative pole of power supply 104 to complete the circuit. At this time, the auxiliary electrode 201 is not connected to the circuit.
When the switching device 202 is closed, one or more auxiliary electrodes 201 are connected to the circuit, resulting in at least two parallel closed-circuit circuits in the entire system: the wafer electroplating circuit (first circuit) and one or more auxiliary electrode 201 circuits (second circuits), with each auxiliary electrode 201 corresponding to one auxiliary electrode 201 circuit.
The wafer electroplating circuit involves current flowing from the positive pole of power supply 104, passing through the bottom anode metal 103 of the electroplating tank 102, the electroplating solution, wafer 105, electroplating head 101, and returning to the negative pole of power supply 104 to form a closed circuit.
The auxiliary electrode 201 circuit involves current flowing from the positive pole of power supply 104, passing through the bottom anode metal 103 of the electroplating tank 102, the electroplating solution, auxiliary electrode 201, circuit resistor assembly 8, and returning to the negative pole of power supply 104 to form a closed circuit.
In this embodiment, each auxiliary electrode 201 has independent control relations. As shown in
The switch triggering device includes a laser communication device, which consists of a signal recognition structure and laser signal transceiver 9. The number of laser signal transceivers 9 matches the number of auxiliary electrodes 201. The laser communication device is used to transmit signals to the control module indicating the closure of the switching device 202. The laser signal transceivers 9 are connected to the control module, which can directly control the closure of the switching device 202 upon receiving signals from the laser signal transceivers 9. Additionally, the control module can adjust the closure time of the switching device 202 through software control.
During the electroplating process, as wafer 105 rotates under the action of electroplating head 101, when the gap of wafer 105 rotates to the period just before approaching and slightly moving away from the auxiliary electrode 201, the switch triggering device can close or open the switching device 202 to adjust the electroplating rate around the wafer gap. Furthermore, the control module can also control, via software, various parameters of the connection path where the auxiliary electrode 201 is located, including the closure time of the switching device 202, power-on interval, pulsation frequency, duty cycle, and resistance value of the circuit resistor assembly 8.
In this embodiment, the signal recognition structure is a signal recognition point 10. Signal recognition point 10 can be an inlay of mirrored metal or a metal mark positioned at the same horizontal height as the laser signal transceiver 304. During electroplating, signal recognition point (10) rotates synchronously with the wafer gap, maintaining a constant relative position. If the positions of auxiliary electrodes 201 are uniformly distributed around the circumference, theoretically, one signal recognition point 10 can serve as a reference. The surface roughness Ra value of signal recognition point 10 should be controlled within the range of 3.2 to 6.3 and should not be black or transparent in color, to allow reflection of laser signals emitted by laser signal transceivers 9. (A smaller surface roughness value indicates a rougher surface.)
During the electroplating process, laser signal transceivers 9 remain continuously on. electroplating head 101 rotates while holding wafer 105, and the wafer gap rotates synchronously. As the wafer gap approaches an auxiliary electrode 201 during rotation, the laser signal falls on the signal recognition point 10 located on the outer edge of electroplating head 101. Signal recognition point 10 reflects the laser signal back to the laser signal transceiver 9. Laser signal transceivers 9 transmit signals to the control module, indicating the closure of the switching device 202. The control module triggers the switching device 202 of the auxiliary electrodes 201 through software control based on these signals.
In this setup, it's necessary to input in advance the duration for which the single switching device 202 remains closed in the software of the control module, which controls the time during which the auxiliary electrode 201 is connected to the circuit. For example, if the input duration for the switching device 202 closure is 0.5 seconds, then each time the laser falls on the signal recognition point 10, the auxiliary electrode 201 remains active for 0.5 seconds after that moment.
By controlling the time during which the switching device 202 connects to the circuit and the rotation speed of wafer 105, precise control over the operational range of each auxiliary electrode 201 can be achieved. As shown in
The operational angle can be adjusted to different sizes according to specific requirements. The size of the operational angle can be controlled by adjusting the duration of the single switching device 202 closure and the rotation speed of wafer 105.
As shown in
During this 60/x seconds, by rotating the screw 205a of the aforementioned liftable support ring structure or adjusting the nut 205b, the liftable support ring can be controlled to move up and down, thus controlling the distance between the auxiliary electrode 201 and the wafer notch. The closer the auxiliary electrode 201 is to the notch, the smaller the electroplating current and the slower the electroplating rate. This allows further dynamic adjustment of the electroplating current within the operational range of the auxiliary electrode 201.
This embodiment provides a device for improving the electroplating uniformity in wafer electroplating. Unlike the device provided in the fourth embodiment, the difference lies in the design of the support ring structure. In this embodiment, the support ring structure is a magnetic levitation support ring. Unlike the liftable support ring in the fourth embodiment, the magnetic levitation support ring in this embodiment can rotate synchronously or asynchronously with the wafer 105. It is equipped with one or several auxiliary electrodes 201 distributed uniformly for electroplating rate adjustment. In this embodiment, three auxiliary electrodes 201 will be used as an example for explanation.
As shown in
As depicted in
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As shown in
A contact point is formed between the conductive ball 211 at the end of the conductive rod 209 connected to each auxiliary electrode 201 and the concave groove of the track on the surrounding rail 210. At this contact point, the conductive ball 211 contacts the metal ring band 212 below the track groove. When the suspended support ring body 204 rotates, the metal ring bands 212 on the tracks do not rotate with it. The conductive balls 211 make point contact with the metal ring bands 212 in the track grooves, rolling along the trajectory of the metal ring bands 212 as the support ring body 204 rotates, thus forming a current conduction path from the support ring body 204 through the auxiliary electrodes 201, conductive rods 209, conductive balls 211, metal ring bands 212, and fixed wires 213. The subsequent circuit or switches connected to the metal ring bands 212 and auxiliary electrodes 201 do not interfere with or affect one another. Each track's metal ring band 212 has only one fixed wire 213, connected to the switching device 202, controlling the auxiliary electrodes 201 connecting to the circuit.
In this embodiment, when the auxiliary electrodes 201 rotate with the support ring structure, to avoid the auxiliary electrodes 201 driving their connected series circuit resistor assembly's wires to rotate and cause wire entanglement, the conductive rods 209 connected to the auxiliary electrodes 201 and the surrounding rail 210 are set up. This setup allows the auxiliary electrodes 201 to make rolling contact with the metal ring bands 212 on the surrounding rail 210 through the conductive balls 211. Simultaneously, each track has a fixed wire 213 connected to the metal ring band 212 to provide a fixed circuit entry point, ensuring that the current is guided to the external circuit without the rotation of the auxiliary electrodes 201 interfering with the external circuit wires. Moreover, each track is insulated from the others, preventing contact short circuits between each independent parallel circuit containing the auxiliary electrodes 201. Additionally, the heights of the metal ring bands 212 on each track are staggered vertically to prevent interference between the fixed wires 213 connecting the metal ring bands 212 to the external circuit and the conductive rods 209 during rotation.
Each auxiliary electrode 201 has an independent circuit relationship. As shown in the circuit diagram in
When the switching devices 202 are open, the current flows from the positive pole of the power supply 104, sequentially passing through the anode metal 103 at the bottom of the electroplating tank 102, the electroplating solution, the wafer 105, and the electroplating head 101, finally returning to the negative pole of the power supply 104, forming a closed circuit. At this time, the auxiliary electrodes 201 are not connected to the circuit.
When the switching devices 202 are closed, one or more auxiliary electrodes 201 are connected to the circuit. There are at least two parallel closed-circuit circuits in the entire circuit, including a wafer electroplating circuit (first circuit) and one or more auxiliary electrode 201 circuits (second circuits), with one auxiliary electrode 201 corresponding to one auxiliary electrode 201 circuit.
The wafer electroplating circuit is where the current flows from the positive pole of the power supply 104, sequentially passing through the anode metal 103 at the bottom of the electroplating tank 102, the electroplating solution, the wafer 105, and the electroplating head 101, finally returning to the negative pole of the power supply 104, forming a closed circuit.
The auxiliary electrode 201 circuit is where the current flows from the positive pole of the power supply 104, sequentially passing through the anode metal 103 at the bottom of the electroplating tank 102, the electroplating solution, the auxiliary electrode 201, the conductive rod 209, the conductive ball 211, the metal ring band 212, the fixed wire 213, the circuit resistor assembly 8, and finally returning to the negative pole of the power supply 104, forming a closed circuit.
In this embodiment, the magnetic levitation support ring can not only control the vertical movement of the support ring body 204 through the current coils at the bottom of the electroplating tank 102 but also control the horizontal rotation of the support ring body 204, driving the auxiliary electrodes 201 via the current coils on the side walls of the electroplating tank 102. This allows the auxiliary electrodes 201 to move closer to or farther from the wafer notch in vertical height and also achieve synchronous or asynchronous rotation with the notch in the horizontal direction. Therefore, the control method for the auxiliary electrodes 201 in this embodiment is more flexible than in the fourth embodiment.
This embodiment provides an electroplating apparatus, including a device for improving electroplating uniformity in wafer electroplating as described in any of the above embodiments.
As shown in
This embodiment proposes a method for improving electroplating uniformity in wafer electroplating. During the electroplating process, by setting one or more parameters such as the closing time of the switching device in the auxiliary electrode's connected path, power interval, pulse frequency, duty cycle, and the resistance value of the circuit resistor assembly 8, precise adjustments can be made to the electroplating rate for a specific area of the wafer over a certain period. The specific usage method can be set through the control module software, whereby the closing time of the switching device 202 in the connected path of the auxiliary electrode 201 is controlled at any time during the stages when the wafer 105 notch approaches, passes, and slightly moves away from the auxiliary electrode 201. Furthermore, it can be set so that the same switching device 202 closing operation is performed each time the wafer 105 notch passes by the auxiliary electrode 201 or after several rotation cycles, or different switching devices 202 closing operations are performed in different rotation cycles. Additionally, by controlling the total current flowing through the auxiliary electrode 201 each time the switching device 202 closes using the series circuit resistor assembly 8, more targeted adjustments can be made to the electroplating rate on the wafer surface near the notch of wafer 105. The impact range and degree can be flexibly adjusted by selecting the switching device 202 closing time and dynamically adjusting the resistance value of the series circuit resistor assembly 8. This method addresses the current challenge of uniformity control in the wafer electroplating process in semiconductor manufacturing, helping to improve wafer yield and enhance production economic efficiency.
As shown in
During the period when the switching device 202 is closed, the screw 205a structure or the adjusting nut 205b of the liftable support ring is mechanically rotated to control the vertical movement of the liftable support ring, thereby controlling the distance of the auxiliary electrode 201 from the wafer notch. The closer the auxiliary electrode 201 is to the notch, the smaller the electroplating current and the slower the electroplating rate, allowing further dynamic adjustment of the electroplating current within the effective range of the auxiliary electrode 201.
As shown in
During the period when the switching device 202 is closed, alternating the direction of current in the coils on the inner and side walls of the electroplating tank 102 through software settings causes the magnetic torque generated by the permanent magnets on the support ring body 204 to alternate in direction. This alternation allows for clockwise or counterclockwise rotation alternately in the horizontal direction and vertical lifting and lowering movements of the magnetic levitation support ring. This controls the distance of the auxiliary electrode 201 from the wafer notch. The closer the auxiliary electrode 201 is to the notch, the smaller the electroplating current and the slower the electroplating rate. Additionally, controlling the current magnitude in the alternating current coils regulates the speed of vertical lifting or rotation of the magnetic levitation support ring, thereby further dynamically adjusting the electroplating current within the effective range of the auxiliary electrode 201.
The above are only the preferable embodiments of the present invention. Without departing from the principles of the present invention, persons skilled in the art can further make improvements and polishments to the above technical solutions. Such improvements and polishments shall be within the protection scope of the present invention. It is worth noting that the stirring device for electroplating of the present invention can comprise one or two or more flow-uniformization plates.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023118515340 | Dec 2023 | CN | national |
| 2024107079272 | Jun 2024 | CN | national |
