Microprocessors, memory devices, field-emission-displays, read write heads and other microelectronic devices generally have integrated circuits with microelectronic components. A large number of individual microelectronic devices are generally formed on a semiconductor wafer, a glass substrate, or another type microelectronic workpiece. In a typical fabrication process, one or more thin metal layers are formed on the workpieces at various stages of fabricating the microelectronic devices to provide material for constructing interconnects between various components.
The metal layers are often applied to the workpieces via electrochemical plating in an electroplating reactor or machine. A typical electroplating reactor includes a container for holding an electroplating solution, an anode in the container to contact the electroplating solution, and a support mechanism having a contact assembly with multiple electrical contacts that engage the seed-layer. The electrical contacts are coupled to a power supply to apply a voltage to the workpiece. In operation, the front surface of the workpiece is immersed in the electroplating solution so that the anode and the workpiece establish an electrical field that causes metal ions in the electroplating solution to plate out onto the workpiece.
In so-called “wet-contact” reactors, the electrical contacts are exposed to the electroplating solution during a plating cycle. Consequently, the metal ions in the electroplating solution also plate out onto the contacts. The contacts, however, may plate at different rates with the result that some contacts can have a relatively greater or lesser surface area contacting the workpiece, as plated-on metal builds up on the contacts over time. This reduces the uniformity of the metal layer plated on the workpiece. It can also contaminate the workpiece via poorly adhering metal particles separating from the contacts and depositing onto the workpiece. To avoid this result, the contacts must be periodically “de-plated” to remove the metal that plates onto the contacts during a plating cycle, as part of ongoing maintenance of the reactor.
Typically, the contacts are deplated by immersing the contact assembly into the plating solution while passing reverse electrical current through them. The reverse current causes the plating cycle to reverse, moving metal off of the contacts and back into the solution. However, the reverse current must be limited to avoid degrading the plating solution. The rate of deplating is also limited by amount of agitation that can be provided to the plating solution around the contacts. Consequently, the contact deplating operation takes significant time to complete. This reduces the throughput or use efficiency of the electroplating reactors. Accordingly, improved designs for deplating contacts are needed.
A new electroplating apparatus having improved contact deplating features has now been invented. In one aspect, this new apparatus generally includes a bowl assembly having a bowl for holding an electroplating solution. A head having a rotor including a contact ring and a head motor for rotating the rotor cooperates with the bowl assembly during plating operations. A lift/rotate actuator may be used to move the head to position a sector of the contact ring in a ring slot or opening of a deplating module. Since the deplating is performed within the deplating module, and not within the bowl assembly, the disadvantages of existing deplating techniques are largely overcome.
In a new method for deplating contacts, a head of plating apparatus or reactor is lifted and then tilted to align a portion of a contact ring on the head with a deplating opening. The contact ring may be extended away from the head and into the deplating opening. The contact ring is rotated to move contacts on the contact ring sequentially through the deplating opening. The contacts are deplated in the deplating opening by exposing the contacts to reverse electrical current in the presence of a deplating solution. The contacts may also be rinsed and dried as they move through the deplating opening.
Other and further objects and advantages will become apparent from the following detailed description. The invention resides as well in subcombinations of the apparatus and methods described.
In the drawings, the same reference number indicates the same element in each of the views.
Turning now in detail to the drawings,
As shown in
Referring to
A deplating fluid supply may be formed via one or more fluid fittings 60 on a fluid distributor block 68 attached to the manifold 70. The contact maintenance module 50 may also be provided with a rinse port 78 in the manifold connected to a rinse fluid source and dry port 80 connected to drying fluid source, such as heated nitrogen gas, via fittings 66, as shown in
As shown in
Turning to
Referring now to
The rotation motor 36 in the head slowly rotates the rotor 34, causing the contact ring 40 to continuously or intermittently move through the ring slot 54. As a result, all of the contacts 41 on the contact ring 40 may be deplated. As shown in
The deplating fluid and the rinse liquid do not enter the bowl assembly 26. Consequently, the plating solution in the bowl assembly 26 is not affected by the deplating process. The ring slot 54 may optionally be provided with separate drain channels for the deplating fluid and the rinse liquid. The deplating fluid can then be recycled and reused. The deplating fluid may be the same as the plating solution contained in the bowl assembly 26, or it may be a different liquid specifically formulated for deplating.
During the deplating process, the motor 36 may move the rotor 36 and the contact ring 40 slowly and continuously without stopping, until all of the contacts 41 on the contact ring 40 have passed through the ring slot 54 and undergone the deplating process one or more times. Alternatively, the motor 36 may move the contact ring 40 incrementally or step-wise through the ring slot 54, with each contact 41 incrementally and sequentially moved through the deplating, rinsing and drying positions, or with a group of from 2 to about 20 contacts moved together through these three positions.
Depending on the design of the contacts and the contact ring, it may be advantageous to pass all of the contacts through the deplating module 50, with the contacts at a first position relative to the electrode(s), for example at a position better adapted to deplate the base of each contact (closer to where the contact is attached to the contact ring). Then the contacts may also make a second pass through the deplating module 50 at a second position relative to the electrode(s), for example with the second position better adapted to deplate the body and/or tip of the contacts. In this method, after the first pass through the deplating module, (i.e., a full rotation of the rotor), the contact ring is withdrawn or retracted slightly away from the electrode(s) 72, for example by about 1-2 or 3 mm.
Consequently, in this method, a head of a plating reactor is pivoted to align a contact ring on a rotor in the head with ring opening in a deplating module. A sector of the contact ring is moved, or extended outwardly from the head, at least partially into the ring opening. An electrically conductive liquid flows over, past or through one or more deplating electrodes in the deplating module, while electrical current flows through the contact ring, the contacts, the conductive liquid and the deplating electrodes. The rotor rotates to move each contact on the contact ring through the deplating module. The contact ring may be rotated once through the deplating module at a first position relative to the deplating electrodes, and then shifted to a second position relative to the deplating electrodes for a second pass through the deplating module.
While
Deplating the contacts may tend to create stray metal particles, as well as sulfuric acid particles, which can cause contamination. It can therefore be advantageous to provide one or more aspiration ports in the manifold adjacent to the contacts in the manifold 70 which may be in between the rinse and dry ports. Aspiration ports, such as port 88 in
Various deplating electrode designs may be used in the contact maintenance module.
Thus, novel apparatus and methods have been shown and described. Various changes and substitutions may of course be made without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims, and their equivalents.
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Entry |
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Korean Intellectual Property Office, International Search Report and Written Opinion for PCT/US2011/047406, Mar. 20, 2012. |
Number | Date | Country | |
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20120037495 A1 | Feb 2012 | US |