Abstract:
Methods and apparatus for aligning a substrate support are provided herein. In some embodiments, a method of aligning a substrate support includes: measuring a tilt of a substrate support along a direction using a tilt sensor disposed on the substrate support; and determining whether the measured tilt of the substrate support in the direction is less than or equal to a predefined value. In some embodiments, a substrate support alignment system includes: a tilt sensor; and a holding element that holds the tilt sensor and which is locatable on a support surface of a substrate support to locate the tilt sensors in a predetermined orientation with respect to the support surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. provisional patent application Ser. No. 62/032,566, filed Aug. 2, 2014, which is herein incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    Embodiments of the present disclosure generally relate to a substrate support in a processing system and, more particularly, to aligning a substrate support in a chamber of a processing system. 
       BACKGROUND 
       [0003]    The alignment of a substrate support within the chamber of a processing system can seriously affect the outcome of a process. For example, in the semiconductor industry, the correct alignment of a substrate support for supporting a semiconductor wafer or other substrate within a process chamber has become a major issue because its misalignment can adversely affect various process parameters. As an example, misalignment of the tilt of the substrate support with respect to a reference plane may cause drift in process parameters. The misalignment of the substrate support can also cause non-uniformity in process outcomes from wafer to wafer. Further, the misalignment between the substrate supports of two or more process chambers can cause inconsistencies in the process results between such chambers. 
         [0004]    However, the inventor has observed that no reliable product or gauge exists that can properly align the substrate support. Present methods may align the pedestal using a dial gauge fixture to align the substrate support to the chamber body. These methods are usually very time consuming and cause personnel to spend a great deal of time in aligning the substrate support. Also, alignment of the substrate support is only possible with respect to a chamber body. Chamber to chamber substrate support alignment with respect to a common reference plane is not possible. 
         [0005]    Accordingly, a method and apparatus for aligning a substrate support within a process chamber is disclosed. 
       SUMMARY 
       [0006]    Methods and apparatus for aligning a substrate support are provided herein. In some embodiments, a method of aligning a substrate support includes: measuring a tilt of a substrate support along a direction using a tilt sensor disposed on the substrate support; and determining whether the measured tilt of the substrate support in the direction is less than or equal to a predefined value. 
         [0007]    In some embodiments, a method of aligning a substrate support in a processing system includes: inserting a substrate support into a processing system; placing two or more tilt sensors on the substrate support; measuring, using the two or more tilt sensors, a degree of tilt of the substrate support along two or more directions; and determining whether the measured degree of tilt of the substrate support along the two or more directions is less than or equal to corresponding predefined values. 
         [0008]    In some embodiments, a substrate support alignment system includes: a tilt sensor; and a holding element that holds the tilt sensor and which is locatable on a support surface of a substrate support to locate the tilt sensors in a predetermined orientation with respect to the support surface. 
         [0009]    Other and further embodiments of the present disclosure are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
           [0011]      FIG. 1  is a diagram illustrating an alignment gauge in accordance with some embodiments of the present disclosure. 
           [0012]      FIG. 2  is a diagram illustrating a system which incorporates an alignment gauge in accordance with some embodiments of the present disclosure. 
           [0013]      FIG. 3  is a diagram illustrating an example of a process chamber and substrate support in which an alignment gauge in accordance with some embodiments of the present disclosure is used. 
           [0014]      FIG. 4  is a flowchart showing an example of a method of aligning a substrate support in accordance with some embodiments of the present disclosure. 
       
    
    
       [0015]    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. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
       DETAILED DESCRIPTION 
       [0016]    Embodiments of the present disclosure provides methods and apparatus to align a substrate support in a process chamber. The inventive methods and apparatus use tilt sensors to measure the position of the substrate support, for example, with respect to a reference plane. The tilt sensors may be mounted on a ring which serves as an alignment gauge. In some embodiments, the tilt sensors may be an accelerometer, such as a micro-electromechanical system (MEMS) accelerometer or the like. The alignment gauge is placed on a substrate support inside a process chamber of a processing system, either on a substrate surface or the substrate support or on a surface surrounding the substrate surface. The alignment gauge measures tilt data with respect to a reference plane, such as a plane aligned to the chamber body, a plane tangential to the surface of the earth, or some other calibrated plane. The measured tilt data is displayed and may be read while a user corrects the substrate support alignment until the displayed tilt data indicates that the substrate support is aligned with the reference plane. 
         [0017]    Accelerometers, such as MEMS accelerometers, can measure acceleration resulting from movement of the accelerometer or can measure static acceleration caused by gravity. Conceptually, an accelerometer consists of a proof mass and restoring springs and behaves as a damped mass on a spring. When the accelerometer experiences an acceleration, the proof mass experiences a force (F=ma) and is displaced in proportion to the force. The displacement is measured to determine the acceleration. For example, the displacement of the proof mass may cause a change in the capacitance between two sensing plates within the accelerometer, and the change in capacitance is used to measure the movement of the proof mass and hence the acceleration. Because the movement of the proof mass is not linear, a sine wave is outputted by the accelerometer which can be used to calculate a linear acceleration. A tilt angle of the substrate support can then be determined using the calculated static acceleration caused by gravity. 
         [0018]      FIG. 1  shows an alignment gauge  100  in accordance with some embodiments of the present disclosure. A holding element  102 , such as a ring as shown in  FIG. 1 , supports one or more tilt sensors  104 . Additional circuitry (for example, as described below with respect to  FIG. 2 ) may be provided to read and/or store tilt data measured by the one or more tilt sensors  104 . 
         [0019]    The holding element  102  is locatable on a support surface of a substrate support to locate the one or more tilt sensors in a predetermined orientation with respect to the support surface. In some embodiments, the predetermined orientation is parallel to a plane containing the support surface. For example, the holding element  102  includes a first side configured to interface with the support surface of the substrate support to be aligned. The one or more tilt sensors may be disposed, for example, on a second side of the holding element  102 , opposite the first side. Although the holding element  102  is shown as a ring in  FIG. 1 , other configurations may be used as well. For example, the holding element may be a disc, rectangle, or other shape suitable to be disposed on a support surface of a substrate support in a predetermined orientation. In some embodiments, the alignment gauge may be a planar member, such as a flat disc, ring, or other planar shape. 
         [0020]    The alignment gauge  100  may be calibrated with respect to a flat reference plane. The reference plane can be a plane of a chamber in which the substrate support is located, a plane tangential to the surface of the earth, or a plane calibrated to the plane tangential to the surface of the earth. As such, the holding element is configured to interface with the substrate support in a predetermined orientation, such that the tilt sensors can measure tilt data corresponding to the orientation of the substrate support with respect to the reference plane. 
         [0021]    The holding element  102  may be configured to interface with (e.g., rest upon) a substrate support in a plane parallel to a plane of a support surface of the substrate support. As such, the holding element  102  may be used to align the plane of the support surface of the substrate support to the reference plane. As used herein, the support surface of the substrate support refers to the surface upon which a substrate rests or is supported during use. 
         [0022]    The one or more tilt sensors may be any devices suitable for measuring the tilt of a substrate support, such as accelerometers, for example, MEMS accelerometers. In some embodiments, the alignment gauge  100  has two tilt sensors, and a degree of tilt of the substrate support may be measured in two directions when the alignment gauge is disposed on the support surface. In some embodiments, the alignment gauge  100  has three tilt sensors, and a degree of tilt of the substrate support may be measured in three directions when the alignment gauge is disposed on the support surface. In some embodiments, each tilt sensor is spaced an equal distance on the ring from adjacent tilt sensors. 
         [0023]      FIG. 2  shows a substrate support alignment system  200  in accordance with some embodiments of the present disclosure that, for example, uses the alignment gauge  100  of  FIG. 1 . The tilt data measured by the alignment gauge  100  is transmitted over a network  202  to a remote device  204 . The network  202  may be a wired or wireless network, such as a Bluetooth network or other local area network. The remote device  204  may be any suitable device for receiving and displaying the measured tilt data, for example, a computer (such as a personal computer or other computer), a smartphone or other handheld device, or the like. The remote device  204  includes a display  206  which can display the measured tilt data using, for example, display software that allows for a two-dimensional or three-dimensional depiction of the substrate support and its alignment to a representation of a reference plane and which may show the changes in the tilt of the substrate support as it is brought into alignment with the reference plane. Alternatively, the measured tilt data may be displayed using numeric or other data. 
         [0024]      FIG. 3  shows an example of substrate support  300  which is inserted inside a process chamber  306  of a processing system and upon which the alignment gauge  100  is placed to determine the alignment of the substrate support  300  with respect to the reference plane. The alignment gauge  100  may be disposed atop a support surface  302  of the substrate support  300  or, as shown, may be disposed atop a ledge  304  that is adjacent to the support surface  302  of the substrate support  300 . An adjustment mechanism  308  is provided to adjust the tilt of the support surface  302 . For example, jack bolts may be disposed about the substrate support  300  or about the support surface  302  to adjust the tilt of the support surface  302  by adjustment of the jack bolts. Alternatively or in combination, a locking mechanism  310  may be provided to secure the support surface  302  in the desired position after checking, and optionally adjusting, the position or orientation of the support surface  302  with respect to the reference plane with the alignment gauge  100 . 
         [0025]      FIG. 4  is a flowchart showing a method  400  of aligning a substrate support in accordance with some embodiments of the present disclosure. The method  400  generally begins at  402 , where a substrate support, such as the substrate support  300  shown in  FIG. 3 , is installed inside a process chamber of a processing system. At  404 , an alignment gauge, such as the alignment gauge  100  shown in  FIGS. 1-3 , is placed on the substrate support. The alignment gauge may be placed on the substrate support before or after installation in the process chamber. Next, at  406 , tilt data measured by the alignment gauge is read from a display, such as in the manner described above. At  408 , it is determined whether alignment is achieved (e.g., if the substrate support is or is not aligned to within a desired tolerance of the reference plane). If alignment is not achieved, then at  410 , the substrate support is adjusted to be brought closer to alignment in response to the tilt data provided by the alignment gauge.  406 ,  408 , and  410  may be repeated until the substrate support is satisfactorily aligned. If necessary, once the substrate support is aligned, then at  412 , the substrate support may be clamped in place or otherwise secured (for example using clamps, bolts, or the like) to retain the substrate support at the proper tilt. 
         [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 thereof.