Abstract:
An apparatus for removing particles from a substrate contact surface includes parallel electrodes disposed beneath the substrate contact surface; and an alternating current (AC) power supply having a first AC terminal connected to a first parallel electrode and a second AC terminal connected to a second parallel electrode adjacent to the first parallel electrode, wherein an AC output of the first AC terminal has a different phase than an AC output of the second AC terminal. A method of removing particles from a substrate contact surface includes supplying a first alternating current (AC) to a first one 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 parallel electrode; wherein the first alternating current has a different phase than the second alternating current.

Description:
FIELD 
       [0001]    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. 
       BACKGROUND 
       [0002]    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. 
         [0003]    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. 
         [0004]    Accordingly, the inventors have provided herein a novel method and apparatus for a self-cleaning particle removal surface to avoid the above problem. 
       SUMMARY 
       [0005]    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. 
         [0006]    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°. 
         [0007]    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. 
         [0008]    Other and further embodiments of the present disclosure are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    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. 
           [0010]      FIG. 1  depicts a schematic view of an electrodynamic screen in accordance with some embodiments of the present disclosure. 
           [0011]      FIG. 2  depicts a schematic side view of a process chamber in accordance with some embodiments of the present disclosure. 
           [0012]      FIGS. 3A and 3B  respectively depict schematic side views of substrate holders in accordance with some embodiments of the present disclosure. 
           [0013]      FIG. 4  depicts a schematic side view of a substrate in accordance with some embodiments of the present disclosure. 
       
    
    
       [0014]    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. 
       DETAILED DESCRIPTION 
       [0015]    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. 
         [0016]      FIG. 1  illustrates an example of an electrodynamic screen and operation of the electrodynamic screen to remove particles from a substrate contact surface  100 . A plurality of parallel electrodes  102 ,  104 ,  106  is embedded below the substrate contact surface  100  in a layer  120 . The plurality of parallel electrodes  102 ,  104 ,  106  may be embedded adjacent to the substrate contact surface  100  or deeper within the layer  120 . The spacing between electrodes may depend on the size of the particles that are to be removed and may depend on the diameter of the electrodes, and may depend on the voltage that may be applied to the electrodes, which may range from about 400 to about 3000 V. The layer  120  may be a polymer layer or of a screen printed material deposited atop a surface of a substrate support or pedestal, a wand, an edge effector, or the like, or the layer  120  may be part of the substrate support or pedestal, wand, or edge effector. 
         [0017]    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 . 
         [0018]    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 . 
         [0019]    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. 
         [0020]      FIG. 2  illustrates an example of a deposition or etch chamber  200  in which first parallel electrodes  232 , second parallel electrodes  234 , and third parallel electrodes  236  are arranged within an upper layer  202  of a pedestal or substrate support  204  and driven in a manner similar to that of the first parallel electrodes  102 , second parallel electrodes  104 , and third parallel electrodes  106  depicted in  FIG. 1 . 
         [0021]    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 . 
         [0022]    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  FIG. 1 , and when the switch  220  connects the DC terminal of the DC source  214  to the leads  222 ,  224 , and  226 , a clamping voltage may be applied to the first parallel electrodes  232 , second parallel electrodes  234 , and third parallel electrodes  236 . 
         [0023]    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 . 
         [0024]      FIGS. 3A and 3B  illustrate an example of wiring arrangements for alternately supplying an AC driving voltage or a DC clamping voltage to first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336 . Though shown as separate figures, the wiring arrangement and power supplies shown in  FIGS. 3A and 3B  are both present in the pedestal or substrate support  304 . As  FIG. 3A  shows, an AC power supply  310  may be connected to the first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336  through the leads  312 ,  314 , and  316 , respectively, to drive the first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336  to remove particles from the substrate contact surface  300  of a dielectric layer  302  of the pedestal or substrate support  304  in a manner similar to that described regarding  FIG. 1 . Alternatively, as  FIG. 3B  shows, a DC power supply  360  may supply a same DC clamping voltage to each one of to the first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336  through the leads  362  and  364  to provide monopolar clamping or may supply a first clamping voltage to one-half of the first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336  through the leads  362 ,  366  and may supply a second clamping voltage, of opposite polarity to first clamping voltage, to the other half of the first parallel electrodes  332 , second parallel electrodes  334 , and third parallel electrodes  336  through the leads  364 ,  368  to provide bipolar clamping. Thus, the same parallel electrodes may advantageously be used to remove particles from the substrate contact surface  300  or to clamp a substrate to the substrate contact surface  300 . 
         [0025]      FIG. 4  illustrates another example of wiring arrangements for alternately supplying an AC driving voltage to a plurality of parallel electrodes disposed within a dielectric layer  402  of a pedestal or substrate support  404  or in an insulating layer  406  formed atop the dielectric layer  402  of the pedestal or substrate support  404 . For example, an AC power supply  410  may supply AC power to the first parallel electrodes  432 , second parallel electrodes  434 , and third parallel electrodes  436  through the leads  412 ,  414 , and  416 , respectively, to drive the parallel electrodes to remove particles from a substrate contact surface  400  in a manner similar to that described regarding  FIG. 1 . Alternatively, DC power supplies  460 ,  461  may supply a same DC voltage to clamping electrodes  466  and  468  through leads  462  and  464 , respectively, to provide monopolar clamping, or the DC power supplies  460 ,  461  may supply DC voltages of opposite polarity to the clamping electrodes  466  and  468 , respectively, to provide bipolar clamping. 
         [0026]    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.