Abstract:
An improved substrate or cover plate design with a groove for effective singulation of individual display apparatus. In one embodiment, the display apparatus comprises a prefabricated groove on an inside face of a substrate or cover plate to facilitate separation of a MEMS device from a plurality of MEMS devices formed a substrate. In some embodiments, the prefabricated grooves make breaking at pseudo scribe lines simple by thinning and weakening the substrate or cover plate at a scribe zone and act as an improved guide for breaking. Scribe cut relief preserves components, structural integrity, and produces a clean break without inducing excessive or unwanted stresses into the MEMS core and ensures no damage at the panel ledge for subsequent interconnect assembly.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to display panels such as multi-layered LCD panels or Microelectromechanical systems (MEMS) display panels with an array of interference modulators, and the manufacturing methods thereof, and more particularly, to the shape and structure of a cover plate or substrate. 
       DESCRIPTION OF RELATED TECHNOLOGY 
       [0002]    Microelectromechanical systems (MEMS) include micro mechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, and or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. One type of MEMS device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In certain embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by an air gap. As described herein in more detail, the position of one plate in relation to another can change the optical interference of light incident on the interferometric modulator. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed. 
         [0003]    In the flat panel display manufacturing industry, a display such as a MEMS device may be manufactured by forming multiple display devices on a substrate and covering the display devices with a protective cover plate attached to the substrate, e.g. via a sealant or adhesive. As a result, the multiple display devices are packaged or sandwiched between the cover plate and substrate. Next, a conventional separation method is used to obtain individually packaged displays or panels from the multiple displays. One separation method is called “scribe and break”. Other separation methods include etching or sandblasting a cover plate or substrate followed by cutting or cracking. 
         [0004]    Conventional scribe and break methods exhibit three steps in the following sequence: score, crack, and separation in normal direction to the glass plate. However, these methods have some unpredictability during the crack and separation steps, as a break away edge may contain additional cracks due to the inter dependence of the scribe and break process and the amount of force or pressure required in a separation method. First, the cutting tools may wear excessively from the force on the glass, or from a heavy load which is required for the separation step. As such, the cutting tools may fail to function properly, leading to unacceptably poor quality edges and more frequent replacement of the tools used to manufacture separation methods. Second, the force may propagate or induce excessive stress waves throughout the core of the display, weakening the display as it is being singulated. Third, the force can create a poor quality separation, by breaking, scratching, and/or shorting out other electronic components, especially the traces on the substrate under the sealant, which is referred to as “Kline out”. This poor quality separation often damages signal traces at the panel ledge, e.g., scratched traces or broken traces exhibiting line out issues on the display. This type of line out problem may be partially alleviated by increased preventive measures such as protective coating on signal traces and/or larger (more robust) signal traces. 
         [0005]    Other separation method problems are related to breakage defects. First, separation methods can cause chipping or “butt wing” instead of producing a smooth and straight break. Second, separation methods often produce glass or other debris because there is not a clean break. These force and breakage defect problems can result in additional manufacturing time and expense such as closer inspections and more rework. 
       SUMMARY 
       [0006]    One embodiment is a method of manufacturing a microelectromechanical systems (MEMS) based display device, the method comprising providing a transparent substrate comprising a first MEMS device and a second MEMS device formed thereon, providing a cover plate, wherein at least one of the cover plate or the substrate includes a groove on an inside face of at least one of the cover plate or the substrate, orienting the cover plate or substrate so that the groove is located in an area between the first and second MEMS devices, joining the cover plate to the substrate to form a first package around the first MEMS device and a second package around the second MEMS device, applying a force between the first and second packages, wherein the force propagates a crack along the groove, and separating the first and second packages. 
         [0007]    In another embodiment, there is a microelectromechanical systems (MEMS) based device, comprising a transparent substrate comprising a first MEMS device and a second MEMS device formed thereon, a cover plate joined to the substrate to form a first package around the first MEMS device and a second package around the second MEMS device, and a groove on an inside face of at least one of the cover plate or the substrate, wherein the groove is between the first and second MEMS devices, wherein an inside face of the cover plate faces an inside face of the substrate, wherein the groove on the inside face of at least one of the cover plate or the substrate reduces a strength of the cover plate or substrate to assist in separating the first and second MEMS devices. 
         [0008]    In another embodiment, there is a microelectromechanical systems (MEMS) based device, comprising a transparent substrate supporting a first MEMS device and a second MEMS device formed thereon, a cover plate for covering the first and second MEMS devices, and means for weakening the substrate or the cover plate, wherein the weakening means is located in an area between the first and second MEMS devices, wherein the cover plate is coupled to the substrate to form a first package around the first MEMS device and a second package around the second MEMS device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is an isometric view depicting a portion of one embodiment of an interferometric modulator display in which a movable reflective layer of a first interferometric modulator is in a relaxed position and a movable reflective layer of a second interferometric modulator is in an actuated position. 
           [0010]      FIG. 2  is a system block diagram illustrating one embodiment of an electronic device incorporating a 3×3 interferometric modulator display. 
           [0011]      FIG. 3  is a diagram of movable mirror position versus applied voltage for one exemplary embodiment of an interferometric modulator of  FIG. 1 . 
           [0012]      FIG. 4  is an illustration of a set of row and column voltages that may be used to drive an interferometric modulator display. 
           [0013]      FIGS. 5A and 5B  illustrate one exemplary timing diagram for row and column signals that may be used to write a frame of display data to the 3×3 interferometric modulator display of  FIG. 2 . 
           [0014]      FIGS. 6A and 6B  are system block diagrams illustrating an embodiment of a visual display device comprising a plurality of interferometric modulators. 
           [0015]      FIG. 7A  is a cross section of the device of  FIG. 1 . 
           [0016]      FIG. 7B  is a cross section of an alternative embodiment of an interferometric modulator. 
           [0017]      FIG. 7C  is a cross section of another alternative embodiment of an interferometric modulator. 
           [0018]      FIG. 7D  is a cross section of yet another alternative embodiment of an interferometric modulator. 
           [0019]      FIG. 7E  is a cross section of an additional alternative embodiment of an interferometric modulator. 
           [0020]      FIG. 8  is a side view illustrating one embodiment of packaged MEMS devices. 
           [0021]      FIG. 9  is a top view illustrating one embodiment of packaged MEMS devices. 
           [0022]      FIG. 10  is a perspective view illustrating one embodiment of packaged MEMS devices with grooves on an inside face of a cover plate. 
           [0023]      FIG. 11  is a side view illustrating one embodiment of packaged MEMS devices with grooves on an inside face of a cover plate with a separation force being applied. 
           [0024]      FIG. 12  is a side view illustrating one embodiment of packaged MEMS devices with grooves on an inside face of a substrate with a separation force being applied. 
           [0025]      FIG. 13  is a side view illustrating one embodiment of packaged MEMS devices with grooves on inside faces of a cover plate and substrate with a separation force being applied. 
           [0026]      FIG. 14  is a flow diagram illustrating one embodiment of manufacturing packaged MEMS devices with grooves on an inside face of a substrate or cover plate. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The following detailed description is directed to certain specific embodiments. However, the teachings herein can be applied in a multitude of different ways. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. The embodiments may be implemented in any device that is configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual or pictorial. More particularly, it is contemplated that the embodiments may be implemented in or associated with a variety of electronic devices such as, but not limited to, mobile telephones, wireless devices, personal data assistants (PDAs), hand-held or portable computers, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, computer monitors, notebook computer displays, tablet PC displays, auto displays (e.g., odometer display, etc.), cockpit controls and/or displays, display of camera views (e.g., display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., display of images on a piece of jewelry). MEMS devices of similar structure to those described herein can also be used in non-display applications such as in electronic switching devices. 
         [0028]    One embodiment of the invention is a MEMS device having a groove on an inside and/or outside face (surface) of a substrate and/or a cover plate. In one embodiment, the groove weakens the cover plate and/or substrate by thinning a scribe zone so that multiple devices can be separated (singulated) with reduced force than might otherwise be needed, so that the reduced force can reduce or eliminate damage to each individual device. As a result, a lower separation force is required to separate devices from one another. Also, the groove reduces the amount of separation force that is propagated or induced throughout the display. 
         [0029]    In another embodiment, the groove on the inside face of the cover plate and/or the substrate acts as a guide that provides a smoother and cleaner separation between devices than might result without the groove. As a result, during separation a smoother break is formed, which prevents chipping or excessive butt wing formation. Also, the cleaner break produces less glass or other debris which can weaken interconnect joints if not removed. Accordingly, in one embodiment, formation of the groove on the cover plate or the substrate provides scribe cut relief to the device in order to allow for an easier separation of multiple devices. 
         [0030]    Although manufacturing of MEMS devices is given as an example where force or pressure can be applied to isolate (singulate) a packaged display, one skilled in the art would be aware that this method and/or apparatus can be applied to other manufactured displays, such as liquid crystal displays (LCD), light emitting diodes (LED), plasma display panels (PDP), and so on. 
         [0031]    One interferometric modulator display embodiment comprising an interferometric MEMS display element is illustrated in  FIG. 1 . In these devices, the pixels are in either a bright or dark state. In the bright (“relaxed” or “open”) state, the display element reflects a large portion of incident visible light to a user. When in the dark (“actuated” or “closed”) state, the display element reflects little incident visible light to the user. Depending on the embodiment, the light reflectance properties of the “on” and “off” states may be reversed. MEMS pixels can be configured to reflect predominantly at selected colors, allowing for a color display in addition to black and white. 
         [0032]      FIG. 1  is an isometric view depicting two adjacent pixels in a series of pixels of a visual display, wherein each pixel comprises a MEMS interferometric modulator. In some embodiments, an interferometric modulator display comprises a row/column array of these interferometric modulators. Each interferometric modulator includes a pair of reflective layers positioned at a variable and controllable distance from each other to form a resonant optical gap with at least one variable dimension. In one embodiment, one of the reflective layers may be moved between two positions. In the first position, referred to herein as the relaxed position, the movable reflective layer is positioned at a relatively large distance from a fixed partially reflective layer. In the second position, referred to herein as the actuated position, the movable reflective layer is positioned more closely adjacent to the partially reflective layer. Incident light that reflects from the two layers interferes constructively or destructively depending on the position of the movable reflective layer, producing either an overall reflective or non-reflective state for each pixel. 
         [0033]    The depicted portion of the pixel array in  FIG. 1  includes two adjacent interferometric modulators  12   a  and  12   b . In the interferometric modulator  12   a  on the left, a movable reflective layer  14   a  is illustrated in a relaxed position at a predetermined distance from an optical stack  16   a , which includes a partially reflective layer. In the interferometric modulator  12   b  on the right, the movable reflective layer  14   b  is illustrated in an actuated position adjacent to the optical stack  16   b.    
         [0034]    The optical stacks  16   a  and  16   b  (collectively referred to as optical stack  16 ), as referenced herein, typically comprise several fused layers, which can include an electrode layer, such as indium tin oxide (ITO), a partially reflective layer, such as chromium, and a transparent dielectric. The optical stack  16  is thus electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more of the above layers onto a transparent substrate  20 . The partially reflective layer can be formed from a variety of materials that are partially reflective such as various metals, semiconductors, and dielectrics. The partially reflective layer can be formed of one or more layers of materials, and each of the layers can be formed of a single material or a combination of materials. 
         [0035]    In some embodiments, the layers of the optical stack  16  are patterned into parallel strips, and may form row electrodes in a display device as described further below. The movable reflective layers  14   a ,  14   b  may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes of  16   a ,  16   b ) to form columns deposited on top of posts  18  and an intervening sacrificial material deposited between the posts  18 . When the sacrificial material is etched away, the movable reflective layers  14   a ,  14   b  are separated from the optical stacks  16   a ,  16   b  by a defined gap  19 . A highly conductive and reflective material such as aluminum may be used for the reflective layers  14 , and these strips may form column electrodes in a display device. Note that  FIG. 1  may not be to scale. In some embodiments, the spacing between posts  18  may be on the order of 10-100 um, while the gap  19  may be on the order of &lt;1000 Angstroms. 
         [0036]    With no applied voltage, the gap  19  remains between the movable reflective layer  14   a  and optical stack  16   a , with the movable reflective layer  14   a  in a mechanically relaxed state, as illustrated by the pixel  12   a  in  FIG. 1 . However, when a potential (voltage) difference is applied to a selected row and column, the capacitor formed at the intersection of the row and column electrodes at the corresponding pixel becomes charged, and electrostatic forces pull the electrodes together. If the voltage is high enough, the movable reflective layer  14  is deformed and is forced against the optical stack  16 . A dielectric layer (not illustrated in this Figure) within the optical stack  16  may prevent shorting and control the separation distance between layers  14  and  16 , as illustrated by actuated pixel  12   b  on the right in  FIG. 1 . The behavior is the same regardless of the polarity of the applied potential difference. 
         [0037]      FIGS. 2 through 5  illustrate one exemplary process and system for using an array of interferometric modulators in a display application. 
         [0038]      FIG. 2  is a system block diagram illustrating one embodiment of an electronic device that may incorporate interferometric modulators. The electronic device includes a processor  21  which may be any general purpose single- or multi-chip microprocessor such as an ARM®, Pentium®, 8051, MIPS®, Power PC®, or ALPHA®, or any special purpose microprocessor such as a digital signal processor, microcontroller, or a programmable gate array. As is conventional in the art, the processor  21  may be configured to execute one or more software modules. In addition to executing an operating system, the processor may be configured to execute one or more software applications, including a web browser, a telephone application, an email program, or any other software application. 
         [0039]    In one embodiment, the processor  21  is also configured to communicate with an array driver  22 . In one embodiment, the array driver  22  includes a row driver circuit  24  and a column driver circuit  26  that provide signals to a display array or panel  30 . The cross section of the array illustrated in  FIG. 1  is shown by the lines  1 - 1  in  FIG. 2 . Note that although  FIG. 2  illustrates a 3×3 array of interferometric modulators for the sake of clarity, the display array  30  may contain a very large number of interferometric modulators, and may have a different number of interferometric modulators in rows than in columns (e.g., 300 pixels per row by 190 pixels per column). 
         [0040]      FIG. 3  is a diagram of movable mirror position versus applied voltage for one exemplary embodiment of an interferometric modulator of  FIG. 1 . For MEMS interferometric modulators, the row/column actuation protocol may take advantage of a hysteresis property of these devices as illustrated in  FIG. 3 . An interferometric modulator may require, for example, a 10 volt potential difference to cause a movable layer to deform from the relaxed state to the actuated state. However, when the voltage is reduced from that value, the movable layer maintains its state as the voltage drops back below 10 volts. In the exemplary embodiment of  FIG. 3 , the movable layer does not relax completely until the voltage drops below 2 volts. There is thus a range of voltage, about 3 to 7 V in the example illustrated in  FIG. 3 , where there exists a window of applied voltage within which the device is stable in either the relaxed or actuated state. This is referred to herein as the “hysteresis window” or “stability window.” For a display array having the hysteresis characteristics of  FIG. 3 , the row/column actuation protocol can be designed such that during row strobing, pixels in the strobed row that are to be actuated are exposed to a voltage difference of about 10 volts, and pixels that are to be relaxed are exposed to a voltage difference of close to zero volts. After the strobe, the pixels are exposed to a steady state or bias voltage difference of about 5 volts such that they remain in whatever state the row strobe put them in. After being written, each pixel sees a potential difference within the “stability window” of 3-7 volts in this example. This feature makes the pixel design illustrated in  FIG. 1  stable under the same applied voltage conditions in either an actuated or relaxed pre-existing state. Since each pixel of the interferometric modulator, whether in the actuated or relaxed state, is essentially a capacitor formed by the fixed and moving reflective layers, this stable state can be held at a voltage within the hysteresis window with almost no power dissipation. Essentially no current flows into the pixel if the applied potential is fixed. 
         [0041]    As described further below, in typical applications, a frame of an image may be created by sending a set of data signals (each having a certain voltage level) across the set of column electrodes in accordance with the desired set of actuated pixels in the first row. A row pulse is then applied to a first row electrode, actuating the pixels corresponding to the set of data signals. The set of data signals is then changed to correspond to the desired set of actuated pixels in a second row. A pulse is then applied to the second row electrode, actuating the appropriate pixels in the second row in accordance with the data signals. The first row of pixels are unaffected by the second row pulse, and remain in the state they were set to during the first row pulse. This may be repeated for the entire series of rows in a sequential fashion to produce the frame. Generally, the frames are refreshed and/or updated with new image data by continually repeating this process at some desired number of frames per second. A wide variety of protocols for driving row and column electrodes of pixel arrays to produce image frames may be used. 
         [0042]      FIGS. 4 and 5  illustrate one possible actuation protocol for creating a display frame on the 3×3 array of  FIG. 2 ,  FIG. 4  illustrates a possible set of column and row voltage levels that may be used for pixels exhibiting the hysteresis curves of  FIG. 3 . In the  FIG. 4  embodiment, actuating a pixel involves setting the appropriate column to −V bias , and the appropriate row to +ΔV, which may correspond to −5 volts and +5 volts respectively Relaxing the pixel is accomplished by setting the appropriate column to +V bias , and the appropriate row to the same +ΔV, producing a zero volt potential difference across the pixel. In those rows where the row voltage is held at zero volts, the pixels are stable in whatever state they were originally in, regardless of whether the column is at +V bias , or −V bias . As is also illustrated in  FIG. 4 , voltages of opposite polarity than those described above can be used, e.g., actuating a pixel can involve setting the appropriate column to +V bias , and the appropriate row to −ΔV. In this embodiment, releasing the pixel is accomplished by setting the appropriate column to −V bias , and the appropriate row to the same −ΔV, producing a zero volt potential difference across the pixel. 
         [0043]      FIG. 5B  is a timing diagram showing a series of row and column signals applied to the 3×3 array of  FIG. 2  which will result in the display arrangement illustrated in  FIG. 5A , where actuated pixels are non-reflective. Prior to writing the frame illustrated in  FIG. 5A , the pixels can be in any state, and in this example, all the rows are initially at 0 volts, and all the columns are at +5 volts. With these applied voltages, all pixels are stable in their existing actuated or relaxed states. 
         [0044]    In the  FIG. 5A  frame, pixels (1,1), (1,2), (2,2), (3,2) and (3,3) are actuated. To accomplish this, during a “line time” for row 1, columns 1 and 2 are set to −5 volts, and column 3 is set to +5 volts. This does not change the state of any pixels, because all the pixels remain in the 3-7 volt stability window. Row 1 is then strobed with a pulse that goes from 0, up to 5 volts, and back to zero. This actuates the (1,1) and (1,2) pixels and relaxes the (1,3) pixel. No other pixels in the array are affected. To set row 2 as desired, column 2 is set to −5 volts, and columns 1 and 3 are set to +5 volts. The same strobe applied to row 2 will then actuate pixel (2,2) and relax pixels (2,1) and (2,3). Again, no other pixels of the array are affected. Row 3 is similarly set by setting columns 2 and 3 to −5 volts, and column 1 to +5 volts. The row 3 strobe sets the row 3 pixels as shown in  FIG. 5A . After writing the frame, the row potentials are zero, and the column potentials can remain at either +5 or −5 volts, and the display is then stable in the arrangement of  FIG. 5A . The same procedure can be employed for arrays of dozens or hundreds of rows and columns. The timing, sequence, and levels of voltages used to perform row and column actuation can be varied widely within the general principles outlined above, and the above example is exemplary only, and any actuation voltage method can be used with the systems and methods described herein. 
         [0045]      FIGS. 6A and 6B  are system block diagrams illustrating an embodiment of a display device  40 . The display device  40  can be, for example, a cellular or mobile telephone. However, the same components of display device  40  or slight variations thereof are also illustrative of various types of display devices such as televisions and portable media players. 
         [0046]    The display device  40  includes a housing  41 , a display  30 , an antenna  43 , a speaker  45 , an input device  48 , and a microphone  46 . The housing  41  is generally formed from any of a variety of manufacturing processes, including injection molding, and vacuum forming. In addition, the housing  41  may be made from any of a variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment the housing  41  includes removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols. 
         [0047]    The display  30  of exemplary display device  40  may be any of a variety of displays, including a bi-stable display, as described herein. In other embodiments, the display  30  includes a flat-panel display, such as plasma, EL, OLED, STN LCD, or TFT LCD as described above, or a non-flat-panel display, such as a CRT or other tube device. However, for purposes of describing the present embodiment, the display  30  includes an interferometric modulator display, as described herein. 
         [0048]    The components of one embodiment of exemplary display device  40  are schematically illustrated in  FIG. 6B . The illustrated exemplary display device  40  includes a housing  41  and can include additional components at least partially enclosed therein. For example, in one embodiment, the exemplary display device  40  includes a network interface  27  that includes an antenna  43  which is coupled to a transceiver  47 . The transceiver  47  is connected to a processor  21 , which is connected to conditioning hardware  52 . The conditioning hardware  52  may be configured to condition a signal (e.g. filter a signal). The conditioning hardware  52  is connected to a speaker  45  and a microphone  46 . The processor  21  is also connected to an input device  48  and a driver controller  29 . The driver controller  29  is coupled to a frame buffer  28 , and to an array driver  22 , which in turn is coupled to a display array  30 . A power supply  50  provides power to all components as required by the particular exemplary display device  40  design. 
         [0049]    The network interface  27  includes the antenna  43  and the transceiver  47  so that the exemplary display device  40  can communicate with one or more devices over a network. In one embodiment the network interface  27  may also have some processing capabilities to relieve requirements of the processor  21 . The antenna  43  is any antenna for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to the IEEE 802.11 standard, including IEEE 802.11(a), (b), or (g). In another embodiment, the antenna transmits and receives RF signals according to the BLUETOOTH standard. In the case of a cellular telephone, the antenna is designed to receive CDMA, GSM, AMPS, W-CDMA, or other known signals that are used to communicate within a wireless cell phone network. The transceiver  47  pre-processes the signals received from the antenna  43  so that they may be received by and further manipulated by the processor  21 . The transceiver  47  also processes signals received from the processor  21  so that they may be transmitted from the exemplary display device  40  via the antenna  43 . 
         [0050]    In an alternative embodiment, the transceiver  47  can be replaced by a receiver. In yet another alternative embodiment, network interface  27  can be replaced by an image source, which can store or generate image data to be sent to the processor  21 . For example, the image source can be a digital video disc (DVD) or a hard-disc drive that contains image data, or a software module that generates image data. 
         [0051]    Processor  21  generally controls the overall operation of the exemplary display device  40 . The processor  21  receives data, such as compressed image data from the network interface  27  or an image source, and processes the data into raw image data or into a format that is readily processed into raw image data. The processor  21  then sends the processed data to the driver controller  29  or to frame buffer  28  for storage. Raw data typically refers to the information that identifies the image characteristics at each location within an image. For example, such image characteristics can include color, saturation, and gray-scale level. 
         [0052]    In one embodiment, the processor  21  includes a microcontroller, CPU, or logic unit to control operation of the exemplary display device  40 . Conditioning hardware  52  generally includes amplifiers and filters for transmitting signals to the speaker  45 , and for receiving signals from the microphone  46 . Conditioning hardware  52  may be discrete components within the exemplary display device  40 , or may be incorporated within the processor  21  or other components. 
         [0053]    The driver controller  29  takes the raw image data generated by the processor  21  either directly from the processor  21  or from the frame buffer  28  and reformats the raw image data appropriately for high speed transmission to the array driver  22 . Specifically, the driver controller  29  reformats the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning across the display array  30 . Then the driver controller  29  sends the formatted information to the array driver  22 . Although a driver controller  29 , such as a LCD controller, is often associated with the system processor  21  as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. They may be embedded in the processor  21  as hardware, embedded in the processor  21  as software, or fully integrated in hardware with the array driver  22 . 
         [0054]    Typically, the array driver  22  receives the formatted information from the driver controller  29  and reformats the video data into a parallel set of waveforms that are applied many times per second to the hundreds and sometimes thousands of leads coming from the display&#39;s x-y matrix of pixels. 
         [0055]    In one embodiment, the driver controller  29 , array driver  22 , and display array  30  are appropriate for any of the types of displays described herein. For example, in one embodiment, driver controller  29  is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, array driver  22  is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, a driver controller  29  is integrated with the array driver  22 . Such an embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, display array  30  is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators). 
         [0056]    The input device  48  allows a user to control the operation of the exemplary display device  40 . In one embodiment, input device  48  includes a keypad, such as a QWERTY keyboard or a telephone keypad, a button, a switch, a touch-sensitive screen, a pressure- or heat-sensitive membrane. In one embodiment, the microphone  46  is an input device for the exemplary display device  40 . When the microphone  46  is used to input data to the device, voice commands may be provided by a user for controlling operations of the exemplary display device  40 . 
         [0057]    Power supply  50  can include a variety of energy storage devices as are well known in the art. For example, in one embodiment, power supply  50  is a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. In another embodiment, power supply  50  is a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell, and solar-cell paint. In another embodiment, power supply  50  is configured to receive power from a wall outlet. 
         [0058]    In some implementations control programmability resides, as described above, in a driver controller which can be located in several places in the electronic display system. In some cases control programmability resides in the array driver  22 . The above-described optimization may be implemented in any number of hardware and/or software components and in various configurations. 
         [0059]    The details of the structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example,  FIGS. 7A-7E  illustrate five different embodiments of the movable reflective layer  14  and its supporting structures.  FIG. 7A  is a cross section of the embodiment of  FIG. 1 , where a strip of metal material  14  is deposited on orthogonally extending supports  18 . In  FIG. 7B , the moveable reflective layer  14  of each interferometric modulator is square or rectangular in shape and attached to supports at the corners only, on tethers  32 . In  FIG. 7C , the moveable reflective layer  14  is square or rectangular in shape and suspended from a deformable layer  34 , which may comprise a flexible metal. The deformable layer  34  connects, directly or indirectly, to the substrate  20  around the perimeter of the deformable layer  34 . These connections are herein referred to as support posts. The embodiment illustrated in  FIG. 7D  has support post plugs  42  upon which the deformable layer  34  rests. The movable reflective layer  14  remains suspended over the gap, as in  FIGS. 7A-7C , but the deformable layer  34  does not form the support posts by filling holes between the deformable layer  34  and the optical stack  16 . Rather, the support posts are formed of a planarization material, which is used to form support post plugs  42 . The embodiment illustrated in  FIG. 7E  is based on the embodiment shown in  FIG. 7D , but may also be adapted to work with any of the embodiments illustrated in  FIGS. 7A-7C  as well as additional embodiments not shown. In the embodiment shown in  FIG. 7E , an extra layer of metal or other conductive material has been used to form a bus structure  44 . This allows signal routing along the back of the interferometric modulators, eliminating a number of electrodes that may otherwise have had to be formed on the substrate  20 . 
         [0060]    In embodiments such as those shown in  FIG. 7 , the interferometric modulators function as direct-view devices, in which images are viewed from the front side of the transparent substrate  20 , the side opposite to that upon which the modulator is arranged. In these embodiments, the reflective layer  14  optically shields the portions of the interferometric modulator on the side of the reflective layer opposite the substrate  20 , including the deformable layer  34 . This allows the shielded areas to be configured and operated upon without negatively affecting the image quality. For example, such shielding allows the bus structure  44  in  FIG. 7E , which provides the ability to separate the optical properties of the modulator from the electromechanical properties of the modulator, such as addressing and the movements that result from that addressing. This separable modulator architecture allows the structural design and materials used for the electromechanical aspects and the optical aspects of the modulator to be selected and to function independently of each other. Moreover, the embodiments shown in  FIGS. 7C-7E  have additional benefits deriving from the decoupling of the optical properties of the reflective layer  14  from its mechanical properties, which are carried out by the deformable layer  34 . This allows the structural design and materials used for the reflective layer  14  to be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer  34  to be optimized with respect to desired mechanical properties. 
         [0061]    Referring now to  FIG. 8 , a side cross-sectional view of packaged MEMS devices  800  is illustrated. As discussed in  FIGS. 1-7 , one type of MEMS device  820  can be an interferometric modulator device that comprises an interferometric modulator array, which selectively transmits, absorbs, and/or reflects light using the principles of optical interference. In  FIG. 8 , the packaged MEMS devices  800  are shown before a manufacturing separation method is used to separate an individual MEMS package  825  from other of the MEMS devices  800 . 
         [0062]    In  FIG. 8 , the MEMS device  820  can be formed on a transparent substrate  830  and covered by a cover plate  810 . As a result, the MEMS device  820  is packaged or sandwiched between the cover plate  810  and substrate  830  to form the package  825 , where an inside face  850  of the cover plate  810  and inside face  855  of the substrate  830  are attached to a sealant  840  with a spacer  875 . The substrate  830  often contains sensitive leads or traces  860  thereon that pass under the sealant  840  to communicate data between the MEMS device  820  and connectors or other electronics located outside of the package  825 . 
         [0063]    The cover plate  810  may be flat as shown in  FIG. 8 , or the cover plate  810  may instead have a curve or recess for fitting closely around the MEMS device  820 . Materials for the cover plate  810  include glass, plastic, or metal. Materials for the substrate  830  include transparent materials. In one embodiment, before separation into one packaged MEMS device, the substrate  830  and cover plate  810  may be a “plate” larger than about 14″×16″, where the plate includes a number of MEMS devices  820 . 
         [0064]    In another embodiment (not shown), the MEMS devices comprise a display that communicates with a processor to process image data, where the processor communicates with a memory device for storing data. This embodiment may also include a driver circuit configured to send at least one signal to the display and a controller configured to send at least a portion of the image data to the driver circuit. This embodiment may also include an image source module configured to send the image data to the processor, where the image source module includes at least one of a receiver, transceiver, and transmitter, and an input device configured to receive input data and to communicate the input data to the processor. 
         [0065]      FIG. 9  is a top view of  FIG. 8 , illustrating one embodiment of the packaged MEMS devices  800  as shown in  FIG. 8  arranged on a plate, before singulation. The cover plate  810  (not shown in this figure) has been removed for illustrative purposes, so that the array of MEMS devices  820   a - i  on the substrate  830  can be seen. Alternatively, the cover plate  810  in this embodiment is clear. Rather than manufacturing each MEMS device  820  separately, the MEMS device  820  is often fabricated as one of many MEMS devices  820  on a relatively large substrate “plate” along with many other MEMS devices  820 , and after the MEMS devices  820  are completed, they are separated from one another. For example,  FIG. 9  illustrates a manufactured plate having 3 rows and 3 columns of MEMS devices  820   a - 820   i , but virtually any number of MEMS devices  820  may be included on the plate, depending on the size of the plate, the size of the MEMS devices  820 , and the required separation between the MEMS devices  820  on the plate. As is discussed further below, one advantage of the embodiments described herein is that the MEMS devices  820  can be more closely arranged on the plate, potentially allowing for a larger number of MEMS devices  820  for a given size of plate. In one embodiment, a prefabricated groove (described below with respect to  FIG. 10 ) is formed before the MEMS device  820  is fabricated onto the substrate  830 . 
         [0066]      FIG. 10  is an exploded perspective view illustrating one embodiment of a plate of packaged MEMS devices  825  before singulation. As illustrated, there are vertical grooves  1010  and horizontal grooves  1020  on the inside face  850  of the cover plate  810 . The grooves  1010  or  1020  can be continuous or discrete. If the grooves are discrete, the grooves  1010  or  1020  can circumscribe around the entire perimeter of the MEMS device  820 , or less than an entire perimeter of the MEMS device  820 . The grooves  1010  or  1020  can be formed by one or more of sandblasting, etching, waterjetting, sawing, laser scribing, or grinding based on the properties of the cover plate  810  or substrate  830 . 
         [0067]    The grooves  1010  or  1020  can reduce a strength of the cover plate  810  and/or substrate  830  at the scribe zone to assist in separating a first MEMS device package  825  from a second MEMS device package  825 . Thus, grooves  1010  or  1020  provide one means for weakening the substrate  830  or the cover plate  810 . This assistance in separation can be from the reduced force required to separate the devices or the reduced force propagated onto the display during singulation. This groove can act as a guide for crack propagation, which is propagated by applying force to the grooves  1010  and/or  1020 . 
         [0068]      FIG. 10  also illustrates pseudo vertical scribe lines  1040  and pseudo horizontal scribe lines  1050  on the outside face  870  of the cover plate  810 . These pseudo scribe lines  1040  and  1050  are located between the individually packaged MEMS devices  825  and are indicated by scribe alignment marks positioned at opposite ends of the cover plate  810  or MEMS devices  820 . Scribe lines are used in the scribe and break method to mark and facilitate breaking the cover plate  810  or substrate  830 . 
         [0069]    As discussed above, scribe cut relief includes the prefabricated grooves  1010  or  1020  on the inside face  850  or  855  of the substrate  830  and/or cover plate  810 . In one embodiment, grooves  1010  or  1020  weaken the cover plate and/or substrate at the scribe zones so that breakage is warranted, requiring less force to separate panels and propagating less stress throughout the display. In another embodiment, the grooves  1010  or  1020  on the inside face  850  or  855  of the cover plate  810  or the substrate  830  act as an improved guide for a smoother and cleaner separation without chips, cracks, and butt wings with less glass debris as compared with a cover plate without grooves. 
         [0070]    Multiple shapes and sizes for the grooves  1010  or  1020  are possible. In one embodiment, the depth of the grooves  1010  or  1020  can be between 100 to 300 microns, where the depth/thickness in  FIG. 8  could be measured as the vertical distance from the inside face  850  or  855  to the outside face  870  or  865  of the cover plate  810  or substrate  830 , respectively. In another embodiment, the depth of the grooves  1010  or  1020  is between 1/7 and ½ a thickness of the cover plate  810  or the substrate. In another embodiment, the width of the groove can be between 100 to 300 microns, where the width in  FIG. 8  would be a horizontal distance. As a result, the depth and width of the groove  1010  or  1020  may be the same or different distances. The depth of the groove can be different percentages of the depth/thickness of the cover plate, including: 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. 
         [0071]    The grooves  1010  or  1020  can be conveniently created on the cover glass  810  during the manufacturing process used to create a recess for the MEMS devices  825 . The grooves  1010  or  1020  can weaken the induced stress waves propagated into the MEMS core. The grooves  1010  or  1020  allow individual packages or panels to be separated without extra loading force. The grooves  1010  or  1020  prevent butt wing formation on an edge of the cover glass  810  or substrate  830 , which would expose a Chip of Glass (COG) zone and Flex on Glass (FOG) zone. Flex can be a flex printed circuit (FPC) board. 
         [0072]    COG and FOG are attachment methods or interconnect schemes. COG refers to the placement, alignment, and bonding of an integrated circuit (IC), such as a display driver IC, at its corresponding footprint on the substrate for electrical connection and for the circuit to process signals for the display core. FOG refers to the placement, alignment, and bonding of one end of the FPC on the substrate at an area adjacent to the COG. FOG sends signals and power to the display via COG. 
         [0073]    The grooves  1010  or  1020  reduce or eliminate scratched or broken traces at a panel ledge. The grooves  1010  or  1020  minimize panel singulation yield loss and quality issue due to unpredictable cover glass cracking and chipping, and butt wing adjacent to the ledge. In addition, the grooves  1010  or  1020  reduce the cost of quality control, inspection, and rework. The grooves  1010  or  1020  are transparent to existing backend flow during singulation and thus can easily be incorporated into process development and volume production environments. Also, the grooves  1010  or  1020  require no real estate increase for the individual MEMS package  825 . 
         [0074]      FIG. 11  illustrates a side view of  FIG. 10 , illustrating one embodiment of a plate of packaged MEMS devices  800  with the grooves  1010  or  1020  on the inside face  850  of the cover plate  810 .  FIG. 11  illustrates a force or separation apparatus  1120  being applied to the cover plate  810 . A separation method often applies inward force on the cover plate  810  or the substrate  830  in order to separate each individual MEMS package  825  into individual panels or packages. In one embodiment, a separation method  1120  is a scribe and break method. Like  FIG. 10 , the grooves  1010  or  1020  provide scribe cut relief. 
         [0075]      FIG. 11  illustrates the grooves  1010  as semi-circular and protruding into the cover plate  810 . However, as discussed above, other shapes and sizes for the grooves  1010  or  1020  are possible. In one embodiment, the depth of the grooves  1010  or  1020  can be between 100 to 300 microns. In another embodiment, the depth of the grooves  1010  or  1020  is between ⅓ and ½ a thickness of the cover plate  810 . In another embodiment, the width of the groove can be between 100 to 300 microns. As a result, the depth and width of the groove  1010  or  1020  may be the same or different dimensions. 
         [0076]      FIG. 12  is a side view illustrating one embodiment of a plate of packaged MEMS devices  800 . As illustrated, the grooves  1010  are located on the inside face  855  of a substrate  830 , instead of the inside face  850  of the cover plate  810 . In  FIG. 12 , the separation force  1120  is being applied to the substrate  830 . 
         [0077]      FIG. 13  is a side view illustrating one embodiment of a plate of packaged MEMS devices  800 . As illustrated, the grooves  1010  are on the inside faces  850  and  855  of both the cover plate  810  and the substrate  830 . The separation method  1120  is applied to the cover plate  810  and the substrate  830 . In this figure, the grooves  1010  are shown in different sizes, shapes, and depths to facilitate singulation. The grooves  1010  or  1020  can be many shapes, such as a straight line, circular, or rectangular. The grooves  1010  or  1020  may also be referred to as a penetration, fenestration, slot, hole, microhollow, trough, exterior window, opening, piercing, etc. 
         [0078]      FIG. 14  is a flow diagram illustrating one embodiment of manufacturing packaged MEMS devices with the grooves  1010  or  1020  on the inside face  850  or  855  of the substrate  830  or the cover plate  810 . In one embodiment, this method takes place in ambient conditions; other embodiments operate in military, commercial, industrial, and extended temperature ranges. 
         [0079]    The manufacturing process starts at step  1400 . Next, at step  1410  a machine or semi-automated process creates the prefabricated grooves  1010  in the substrate  830  and/or the cover plate  810 . Proceeding to step  1420 , a machine or semi-automated process orients the cover plate  810  over the MEMS devices  820  formed on the substrate  830 , so that the grooves are located in an area between each individual MEMS package  825 . The cover plate  810  and substrate  830  can then be joined or fabricated together using a sealant  840 . Subsequently, step  1430  separates the individually packaged MEMS device  825  along the grooves  1010  or  1020  using force or a separation method  1120 , where the grooves  1010  or  1020  weaken the substrate  830  or cover plate  810  containing the grooves  1010  or  1020  or acts as an additional guide for breaking. As discussed above, scribe cut relief includes the grooves  1010  or  1020  which require less force, propagate less stress on the display, and produce less chipping/debris. 
         [0080]    The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in a computer or electronic storage, in hardware, in a software module executed by a processor, or in a combination thereof. A software module may reside in a computer storage such as in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a mobile station. In the alternative, the processor and the storage medium may reside as discrete components in a mobile station. 
         [0081]    The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.