Patent Application
20170056934
Electroplating has many applications. One very important developing application is in electroplating copper onto semiconductor wafers to form conductive copper lines for “wiring” individual devices of the integrated circuit. Often this electroplating process serves as a step in the damascene fabrication procedure.
For example, wafers are inserted in a substrate holder and then immersed into an electroplating bath to perform the electroplating process. After the electroplating process is completed, the wafers are removed from the electroplating bath. However, after electroplating of several batches of wafers, contamination is found on the substrate holder, which may induce inline gap-filling defects during the electroplating process, and thus to deteriorate the process yield. What is needed therefore is improved technology for removing the contamination on the substrate holder.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
Electrochemical deposition may be employed at various points in the integrated circuit fabrication and packaging processes. At the integrated circuit (IC) chip level, damascene features are created through electrodepositing copper within vias and trenches to form multiple interconnected metallization layers. However, after electrochemical deposition is performed on several batches of wafers, contamination is found on the substrate holder, which may induce inline gap-filling defects during the electrochemical deposition, and thus to deteriorate the process yield. Specifically, the contamination may be dropped into the vias or the trenches, which may result in the gap-filling defects. The contamination may be particles, unwanted deposits, recrystallized components (e.g., copper sulfate or a mixture of copper sulfate and additive) or other materials. What is needed therefore is improved technology for removing the contamination on the substrate holder.
Currently, the substrate holder is cleaned by immersing the substrate holder into the electroplating bath to remove the contamination on the substrate holder. Nevertheless, such cleaning process typically takes more than ten minutes. Furthermore, the cleaning process may be performed with high frequency, and thus will significantly lower wafer throughput per hour (WPH).
Therefore, the present disclosure provides a cleaning device for effectively removing contamination on a substrate holder used with an electroplating cell. In some embodiments, the cleaning process using the cleaning device takes less than or much less than ten minutes, and thus will improve the wafer throughput per hour (WPH). Embodiments of the electroplating cell, the substrate holder and the cleaning device are sequentially described in detail below.
In some embodiments, the electroplating cell (not shown) has an electroplating chamber, which may house an anode chamber and an electroplating solution. In some embodiments, the electroplating cell further includes other functional elements, such as a diffuser, an electroplating solution inlet tube, a rinse drain line, an electroplating solution return line, any other functional element or a combination thereof.
In some embodiments, the electroplating cell is included in an electroplating tool (not shown) for electroplating semiconductor wafers. Semiconductor wafers may be fed to the electroplating tool. A robot can retract and move the substrates in multiple dimensions from one station to another station. The electroplating tool may also include other modules configured to perform other necessary electroplating sub-processes, such as spin rinsing and drying, metal and silicon wet etching, pre-wetting and pre-chemical treating, photoresist stripping, surface pre-activation, etc.
The substrate holder is used with the electroplating cell. The substrate holder is configured to receive and support a substrate (e.g., a semiconductor wafer) during electroplating deposition. The term “substrate holder” may also be called as wafer holder, workpiece holder, clamshell holder, clamshell assembly and clamshell. In some embodiments, the substrate holder is Novellus Systems' Sabre® tool. In some embodiments, the substrate holder can be lifted vertically either up or down to immerse the wafer holder into the electroplating solution in the electroplating cell via an actuator.
In some embodiments, the substrate holder (not shown) includes two main components of a clamshell, which are a cup and a cone. In some embodiments, the cup is configured to provide a support upon which the substrate rests. In some embodiments, the cone is over the cup and configured to press down on a backside of the substrate to hold it in place. In some embodiments, the substrate holder further includes struts to support the cup and the cone. In some embodiments, the substrate holder is driven by a motor. In some embodiments, the substrate holder is driven by a motor via a spindle. In some embodiments, the spindle transmits torque from the motor to the substrate holder causing rotation of the substrate held therein during the electroplating process. In some embodiments, an air cylinder within the spindle also provides a vertical force for engaging the cup with the cone. In some embodiments, the substrate is loaded between the cone and the cup when the clamshell is disengaged. The cone is engaged with the cup after the substrate is loaded to engage the substrate against the periphery of the cup.
In some embodiments, the cup includes a cup bottom, a plurality of lip seals and a plurality of electrical contacts. In some embodiments, the lip seals and the electrical contacts surround the cup bottom, and the electrical contacts are over the lip seals.
The cup bottom 212 is also referred to as a “disk” or a “base plate.” The cup bottom 212 may be made of a stiff, corrosive resistant material, such as stainless steel, titanium, and tantalum. The cup bottom 212 may be removed (i.e., detached) to allow replacing various elements of the cup. The cup bottom 212 may have a tapered edge (not marked) at its innermost periphery, which is shaped in such ways as to improve flow characteristic of the electroplating solution around the edge.
During closing, the cup bottom 212 supports the lip seals 214 when the force is exerted through a substrate 300 to avoid clamshell leakage during the substrate 300 immersion. That is, the lip seals 214 are configured to engage with the edge of the substrate 300 and to form a seal between the substrate 300 and the lip seals 214 that protects the interior of the cup from the electroplating solution. In some embodiments, the lip seals 214 are made of an elastic material or any other suitable material.
The electrical contacts 216 are configured to establish electrical connection with conductive elements of the substrate 300. In some embodiments, the electrical contacts 216 are made of alloy or any other suitable material. In some embodiments, the electrical contacts 216 are flexible and may be pushed down (i.e., towards the tapered edge of the cup bottom 212) when the substrate 300 is loaded.
In order to effectively remove the contamination on the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof of
In some embodiments, the cleaning device is an auto-clean-etch (ACE) module and exhibits multiple process capability and high contamination removal efficiency, and thus able to maintain stable peak current during the electroplating process and to reduce gap-filling defects and to improve wafer throughput per hour (WPH). For example, the multiple process capability may include multiple selections of the cleaning agent and multiple parameters (e.g., order, temperature) of the cleaning process.
In some embodiments, the arm 110 is coupled to the nozzle 130 and configured to position the nozzle 130 to effectively remove the contamination on the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof). In some embodiments, the arm 110 is positioned by a controller (not shown). In some embodiments, the arm 110 is able to move or rotate.
In some embodiments, the arm 110 is coupled to the cleaning agent supplier 120. In some embodiments, the arm 110 is coupled to the receiver 140. In some embodiments, the arm 110 is connected to the receiver 140. In some embodiments, as shown in
In some embodiments, the cleaning agent supplier 120 is configured to supply a cleaning agent. In some embodiments, the cleaning agent supplier 120 includes one or more piping lines (not marked) for transferring the cleaning agent to one or more nozzles 130. In some embodiments, the cleaning agent supplier 120 is embedded in the arm 110, as shown in
In some embodiments, the cleaning agent supplied from the cleaning agent supplier 120 includes acid, dry solvent, inert gas, any other suitable material or a combination thereof. In some embodiments, the acid is used to dissolve or etch the contamination. In some embodiments, the acid includes organic acid, inorganic acid or a combination thereof. In some embodiments, the inorganic acid includes sulfuric acid, hydrochloric acid, nitric acid, any other suitable inorganic acid or a combination thereof. In some embodiments, the dry solvent includes isopropyl alcohol (IPA), acetone, methyl ethyl ketone (MEK), any other suitable dry solvent or a combination thereof. In some embodiments, the inert gas includes nitrogen, argon, helium, any other suitable inert gas or a combination thereof.
In some embodiments, the nozzle 130 is configured to spray the cleaning agent onto the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof) to remove the contamination. In some embodiments, the nozzle 130 is coupled to the cleaning agent supplier 120. In some embodiments, the nozzle 130 is connected to the cleaning agent supplier 120, as shown in
In some embodiments, the receiver 140 is configured to receive the cleaning agent after the cleaning agent is sprayed onto the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof) to avoid contamination of the electroplating solution. In some embodiments, the receiver 140 is configured to surround the lip seal 214. In some embodiments, the receiver 140 is configured to surround the lip seal 214 and the electrical contact 216. In some embodiments, the receiver 140 is a sink, which can be used to accommodate a portion of the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof). In some embodiments, the receiver 140 includes a vent 142 on the receiver 140 and configured to suck up the cleaning agent to avoid overflow of the cleaning agent. In some embodiments, the vent 142 is on a bottom surface of the receiver 140. In some embodiments, the vent 142 is embedded (or inserted) in a bottom of the receiver 140.
In some embodiments, the receiver 140 is configured to receive a cleaning agent after the cleaning agent is sprayed onto a substrate holder (e.g., a lip seal 214, a electrical contact 216, a cup bottom 212 or a combination thereof) to avoid contamination of the electroplating solution. The receiver 140 may be designed to various shapes according to the shape of a portion of the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof) and/or other considerations. In some embodiments, the receiver 140 includes a bottom 140a, a ceiling 140b and a sidewall 140c connected between the bottom 140a and the ceiling 140b, as shown in
In some embodiments, the receiver 140 includes a vent 142 on the receiver 140 and configured to suck up the cleaning agent to avoid overflow of the cleaning agent. In some embodiments, the vent 142 is on the bottom 140a of the receiver 140. In some embodiments, the vent 142 is embedded (or inserted) in the bottom 140a of the receiver 140.
In some embodiments, the cleaning agent supplier 120 is configured to supply the cleaning agent. In some embodiments, the cleaning agent supplier 120 includes one or more piping lines (not marked) for transferring the cleaning agent to the first and second nozzles 132, 134. In some embodiments, the cleaning agent supplier 120 is embedded in the receiver 140, as shown in
In some embodiments, the first nozzle 132 is on the ceiling 140b of the receiver 140 and coupled to the cleaning agent supplier 120 to spray the cleaning agent onto the lip seal 214. In some embodiments, the second nozzle 134 is on the sidewall 140c of the receiver 140 and coupled to the cleaning agent supplier 120 to spray the cleaning agent onto the lip seal 214.
In some embodiments, the receiver 140 is configured to receive a cleaning agent after the cleaning agent is sprayed onto a substrate holder (e.g., a lip seal 214, a electrical contact 216, a cup bottom 212 or a combination thereof) to avoid contamination of the electroplating solution. The receiver 140 may be designed to various shapes according to the shape of a portion of the substrate holder (e.g., the lip seal 214, the electrical contact 216, the cup bottom 212 or a combination thereof) and/or other considerations. In some embodiments, the receiver 140 includes a bottom 140a, a ceiling 140b and a sidewall 140c connected between the bottom 140a and the ceiling 140b, as shown in
In some embodiments, the receiver 140 includes a vent 142 on the receiver 140 and configured to suck up the cleaning agent to avoid overflow of the cleaning agent. In some embodiments, the vent 142 is on the bottom 140a of the receiver 140. In some embodiments, the vent 142 is embedded (or inserted) in the bottom 140a of the receiver 140.
In some embodiments, the cleaning agent supplier 120 is configured to supply the cleaning agent. In some embodiments, the cleaning agent supplier 120 includes one or more piping lines (not marked) for transferring the cleaning agent to the first and second nozzles 132, 134. In some embodiments, the cleaning agent supplier 120 is embedded in the receiver 140, as shown in
In some embodiments, the first nozzle 132 is on the first portion 1401b of the ceiling 140b of the receiver 140 and coupled to the cleaning agent supplier 120 to spray the cleaning agent onto the lip seal 214. In some embodiments, the second nozzle 134 is on the sidewall 140c of the receiver 140 and coupled to the cleaning agent supplier 120 to spray the cleaning agent onto the lip seal 214.
In some embodiments, the cleaning device 10 further includes a third nozzle 136 on the second portion 1402b of the ceiling 140b of the receiver 140. The first, second and third nozzles 132, 134 and 136 may align with different portions of the lip seal 214. In other embodiments, a plurality of nozzles may align with a same portion of the lip seal. It is noted that, the amount, the position and the spray direction of the nozzles may be altered in practical applications.
In some embodiments, the lip seal 214 includes a lip portion 214a configured to be against a substrate (e.g., the substrate 300 of
As shown in
First, as shown in
In operation 404, the cleaning agent is sprayed (or rinsed) onto the portion of the substrate holder 20 through the nozzle to remove the contamination, as shown in
In some embodiments, spraying the cleaning agent onto the portion of the substrate holder 20 includes: spraying an acid onto the portion of the substrate holder 20; spraying an dry solvent onto the portion of the substrate holder 20 after spraying the acid onto the portion of the substrate holder 20; and spraying inert gas onto the portion of the substrate holder 20 after spraying the dry solvent onto the portion of the substrate holder. The species of the cleaning agents, the spray order and the spray position may be appropriately changed in other embodiments and not limited to the embodiments exemplified above.
In some embodiments, as shown in
In operation 406, the cleaning agent is received through the receiver 140 after the cleaning agent is sprayed onto the portion of the substrate holder 20, as shown in
According to some embodiments, a cleaning device for removing contamination on a substrate holder used with an electroplating cell includes an arm, a cleaning agent supplier, a nozzle and a receiver. The cleaning agent supplier is coupled to the arm and configured to supply a cleaning agent. The nozzle is coupled to the cleaning agent supplier and configured to spray the cleaning agent onto the substrate holder to remove the contamination. The receiver is coupled to the arm and configured to receive the cleaning agent after the cleaning agent is sprayed onto the substrate holder.
According to some embodiments, a cleaning device for removing contamination on a lip seal of a substrate holder used with an electroplating cell includes a receiver, a cleaning agent supplier, a first nozzle and a second nozzle. The receiver includes bottom, a ceiling and a sidewall between the bottom and the ceiling. The cleaning agent supplier is configured to supply a cleaning agent. The first nozzle is on the ceiling of the receiver and coupled to the cleaning agent supplier to spray the cleaning agent onto the lip seal. The second nozzle is on the sidewall of the receiver and coupled to the cleaning agent supplier to spray the cleaning agent onto the lip seal.
According to some embodiments, a method of removing contamination on a substrate holder in an electroplating cell using the cleaning device described above includes: moving the arm to align the nozzle with a portion of the substrate holder; spraying the cleaning agent onto the portion of the substrate holder through the nozzle to remove the contamination; and receiving the cleaning agent through the receiver after the cleaning agent is sprayed onto the portion of the substrate holder.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
