Patent Application
20160236245
Embodiments of the present disclosure generally relate to support surfaces of substrate supports and, more particularly, to removing particles from the support surfaces of the substrate supports.
The presence of defects caused by particles in microelectronic devices or circuits formed on a substrate negatively impacts product yield. Particles may be generated by either chemical or mechanical sources. For example, during a deposition process, a film may be deposited on the inner surface of a process chamber which, in combination with repeated thermal cycling of the process chamber, may cause the film to delaminate and generate particles as well as cause flaking. As another example, mechanical abrasion with contact surfaces may also generate particles. The particle sizes of concern for manufacturing microelectronic devices or circuits may range from 50 nanometers and above.
Currently, defect reduction is directed at eliminating the defects caused by particles located at the front side of the substrate, namely, the side where dies are formed. However, the inventors have observed that particles are also often generated at the backside of the substrate because of contact with various system components during substrate handling and during chamber processing. For example, the substrate may be transferred into and out of a process chamber using a wand or an end effector of a robot, and the substrate may rest in the chamber on an electrostatic chuck or other substrate support, and over time, particles are generated at the substrate backside as a result of trapped residues and micro-scratches. The inventors have further observed that the generated particles may adhere to the surface of the substrate support, wand or end effector after contacting the substrate, and the adhered particles may be transferred to the back surface of a subsequently handled or processed substrate. The transferred particles may be carried with the subsequently processed substrates into other processing locations in a facility and become an unpredictable source of the particles that may negatively impact yield.
Accordingly, the inventors have provided herein a novel method and apparatus for a self-cleaning particle removal surface to avoid the above problem.
Apparatus and methods for removing particles from a substrate contact surface are provided herein. In some embodiments, an apparatus for removing particles from a substrate contact surface includes a plurality of parallel electrodes disposed beneath the substrate contact surface; and an alternating current (AC) power supply having a first AC terminal connected to a first one of the parallel electrodes and a second AC terminal connected to a second one of the parallel electrodes adjacent to the first one of the parallel electrodes, wherein an AC output of the first AC terminal has a different phase than an AC output of the second AC terminal.
In some embodiments, a substrate support includes parallel electrodes disposed beneath a support surface of the substrate support; and an alternating current (AC) power supply having a first AC terminal connected to a first one of the parallel electrodes, a second AC terminal connected to a second one of the parallel electrodes adjacent to the first one of the parallel electrodes, and a third AC terminal connected to a third one of the parallel electrodes adjacent to the first one of the parallel electrodes, wherein a phase difference between the AC outputs of any two of the first, second, and third AC terminals is 120°.
In some embodiments, a method of removing particles from a substrate contact surface includes supplying a first alternating current (AC) to a first one of a plurality of parallel electrodes disposed beneath the substrate contact surface; and supplying a second alternating current to a second one of the parallel electrodes disposed adjacent to the first one of the parallel electrodes; wherein the first alternating current has a different phase than the second alternating current.
Other and further embodiments of the present disclosure are described below.
Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of the present disclosure provide apparatus and methods for removing particles from a surface that comes in contact with a substrate, referred herein as a substrate contact surface. The substrate contact surface may be a surface of a substrate support or pedestal, a wand, an edge effector, or the like. Embodiments of the present disclosure may advantageously reduce contamination accumulated on a substrate contact surface during the manufacturing process, such as while the substrate is disposed on a substrate contact surface of a substrate support during a process or while the substrate is in contact with a substrate contact surface of a wand or edge effector that is handling the substrate between process steps, which can further limit or prevent contaminants from reaching the front-side of a substrate and causing device performance issues and/or yield loss. Embodiments of the present disclosure may be used in a wide variety of substrate contact surfaces that contact a substrate in processes where very low addition of particles is desired, for example, in display processing, silicon wafer processing, optics manufacturing, and the like.
First parallel electrodes 102 are connected to a first terminal 112 of an alternating current (AC) power supply 110, and second parallel electrodes 104 are connected to a second terminal 114 of the AC power supply 110. The plurality of parallel electrodes 102, 104 may be arranged such that each one of the second parallel electrodes 104 is disposed adjacent to at least one of the first parallel electrodes 102. A two-phase or three-phase alternating current may then be provided to the plurality of parallel electrodes 102, 104 such that the first parallel electrodes 102 are at a different phase than the second parallel electrodes 104. For example, the first parallel electrodes 102 may be a half-cycle apart or one-third of a cycle apart from the second parallel electrodes 104.
Third parallel electrodes 106 may also be provided and are connected to a third terminal 116 of the AC power supply 110. The third parallel electrodes 106 may be arranged such that each of the third parallel electrodes 106 may be disposed, for example, between one of the first parallel electrodes 102 and one of the second parallel electrodes 104. A three-phase alternating current may then be provided such that the first parallel electrodes 102, the second parallel electrodes 104, and the third parallel electrodes 106 are each at different phases of an AC cycle. For example, each one of the first parallel electrodes 102 may be one-third of a cycle ahead of each one of the second parallel electrodes 104 and may be one-third of a cycle behind each one of the third parallel electrodes 106.
By driving the first parallel electrodes 102 and the second parallel electrodes 104 at different phases of the AC cycle, or by driving the first parallel electrodes 102, the second parallel electrodes 104, and the third parallel electrodes 106 at different phases of an AC cycle, the plurality of parallel electrodes generates a travelling electrostatic wave, also known as an electrodynamic screen or an electric curtain. When the AC cycle applies a maximum positive or negative voltage to the parallel electrode closest to the particle, the electric field generated induces an opposite charge on the side of the particle that faces that parallel electrode, namely, the electric field causes the particle to be electrically polarized. Then, when the polarity of the parallel electrode is reversed so that the charge on the electrode is the same as that of the facing side of the particle, the particle is repelled away from the parallel electrode and toward an adjacent parallel electrode that is at a 120 or 180 degree phase difference. When the AC cycle next drives the adjacent parallel electrode to have the same the polarity as the particle, the particle is repelled away from the adjacent parallel electrode and toward a further adjacent parallel electrode that is at a 120 or 180 degree phase difference from the adjacent parallel electrode. As the AC cycle repeats, the travelling wave of the maximum positive or negative voltage moves the particle along the parallel electrodes, i.e., along the substrate contact surface 100, until the particle is removed from the substrate contact surface 100. The frequency of the AC cycle may be sufficiently high enough, such as from about 5 to about 200 Hz, such that the particle is removed from the substrate contact surface 100 before the particle returns to an original, non-polarized state. The distance between, for example, the first parallel electrode 102 and the second parallel electrode 104 may be sufficiently small, such as from about 0.5 to about 2 mm, such that the particle is removed from the substrate contact surface 100 before the particle returns to an original, non-polarized state. The electrodynamic screen therefore advantageously provides a substrate contact surface 100 that is self-cleaning.
An AC source 212, which may be a high voltage AC source, provides an AC voltage to the first parallel electrodes 232, second parallel electrodes 234, and third parallel electrodes 236. For example, each one of the first parallel electrodes 232 may be one-third of a cycle ahead of each one of the second parallel electrodes 234 and may be one-third of a cycle behind each one of the third parallel electrodes 236. The AC source 212 supplies power to the first parallel electrodes 232 through lead 222, supplies power to the second parallel electrodes 234 through lead 224, and supplies power to the third parallel electrodes 236 through lead 226.
Additionally, a direct current (DC) source 214, which may be a high voltage DC source, may provide a same DC clamping voltage to each one of the first parallel electrodes 232, second parallel electrodes 234, and third parallel electrodes 236 through each one of the leads 222, 224, and 226, respectively. A switch 220 selectively couples either an AC terminal of the AC source 212 or a DC terminal of the DC source 214 to the leads 222, 224, and 226 and may be driven by switching circuit 216 which is under the control of a user input 218. When the switch 220 connects the AC terminal of the AC source 212 to the leads 222, 224, and 226, the first parallel electrodes 232, second parallel electrodes 234, and third parallel electrodes 236 are driven to remove particle from atop the pedestal or substrate support 204 in a manner similar to that described regarding
By providing the capability of supplying an AC voltage or a DC voltage, the pedestal or substrate support 204 advantageously may operate as an electrostatic chuck or as an electrodynamic screen. For example, the electrostatic chuck may be used to secure a substrate during an etch or deposition process in the deposition or etch chamber 200 or to remove particles from substrate contact surface 201 atop pedestal or substrate support 204 surface during idle time of the deposition or etch chamber 200.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope of the disclosure as described herein.
