CN100501494C - MEMS device fabricated on pre-patterned substrate - Google Patents

Abstract

A MEMS device is fabricated on a pre-patterned substrate having a recess formed therein. A lower electrode is deposited on the substrate and separated from the orthogonal upper electrode by a cavity. The upper electrode is configured to be movable to modulate reflected light. A semi-reflective layer and a transparent material are formed over the movable upper electrode.

Description

MEMS devices fabricated on pre-patterned substrates

technical field

The technical field of the invention relates to microelectromechanical systems (MEMS) and the packaging of such systems. More specifically, the technical field of the invention relates to interferometric modulators and methods of fabricating such interferometric modulators on a pre-patterned substrate.

Background technique

Microelectromechanical systems (MEMS) include micromechanical components, actuators, and electronics. Micromechanical elements may be fabricated using deposition, etching, or other micromachining processes that etch away portions of substrates and/or deposited material layers, or that add layers to form electrical and electromechanical devices. One type of MEMS device is known as 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 some embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be fully or partially transparent and/or reflective and capable of relatively mobile. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate, while the other plate may comprise a thin metal film separated from the stationary layer by an air gap or cavity. As explained in more detail herein, the position of one plate relative to another can change the optical interference of light incident on the interferometric modulator. These devices have a wide range of applications, and it would be beneficial in the art to exploit and/or modify the properties of these types of devices so that their properties can be used to improve existing products and create new ones not currently developed.

Contents of the invention

The systems, methods, and devices of the invention each have several aspects, no single one of which is solely responsible for its desirable characteristics. Now, its more main characteristics will be briefly described, but this does not limit the scope of the invention. After considering this discussion, and particularly after reading the section entitled "Detailed Description of Preferred Embodiments," one can understand how the features of this invention provide advantages over other display devices. Embodiments described herein provide a package structure and a method of fabricating a package structure under ambient conditions.

One embodiment provides a method of fabricating a MEMS device. A substrate having a plurality of trenches is provided. At least one layer is deposited on the substrate, wherein the layer is discontinuous at the trench. A first cavity is formed between a first electrode formed on the substrate and a second electrode, wherein the at least one layer includes the first electrode.

According to another embodiment, a display device is provided, which includes: a substrate having a plurality of grooves therein, a first electrode and a second electrode formed on a top surface of the substrate, a semi-reflective and a transparent material formed on the chromium layer. The first electrode and the second electrode are insulated from each other and separated by a first cavity. The semi-reflective layer is separated from the second electrode by a second cavity.

According to yet another embodiment, a method of forming a MEMS device is provided. A substrate is provided having a top surface, wherein a plurality of grooves are formed in the top surface. At least one layer is deposited over the substrate, wherein the at least one layer comprises a first conductive material and is discontinuous at the grooves, forming individual rows of the layer on the top surface. A second conductive material is deposited, wherein the second conductive material is oriented orthogonally to the first conductive material on the top surface.

According to another embodiment, a display device is provided. The display device includes: a substrate having a plurality of grooves formed therein, a first reflection member formed on a top surface of the substrate for reflecting light, and a second reflection member for reflecting light , a semi-reflective layer separated from the second reflective member by a second cavity, and a viewing member for transmitting light. The first reflective member and the second reflective member are insulated from each other and separated by a first cavity, and the viewing member is formed on the semi-reflective layer.

Description of drawings

These and other aspects of the invention will become apparent from the following description and accompanying drawings (not drawn to scale), which are intended to illustrate rather than limit the invention, in which:

Figure 1 is an isometric view showing a portion of an embodiment of an interferometric modulator display with a movable reflective layer of a first interferometric modulator in a relaxed position and a second interferometric modulator A movable reflective layer is in an activated position.

2 is a system block diagram illustrating an embodiment of an electronic device including a 3x3 interferometric modulator display.

3 is a graph of movable mirror position versus applied voltage for an example embodiment of the interferometric modulator shown in FIG. 1 .

Figure 4 is a schematic diagram of a set of row and column voltages that may be used to drive an interferometric modulator display.

FIG. 5A illustrates an example display data frame in the 3×3 interferometric modulator display shown in FIG. 2 .

Figure 5B illustrates one example timing diagram of the row and column signals that may be used to write the frame shown in Figure 5A.

6A and 6B are system block diagrams illustrating an embodiment of a visual display device including multiple interferometric modulators.

FIG. 7A is a cross-sectional view of the device shown in FIG. 1 .

Figure 7B is a cross-sectional view of an alternate embodiment of an interferometric modulator.

Figure 7C is a cross-sectional view of another alternative embodiment of an interferometric modulator.

Figure 7D is a cross-sectional view of yet another alternative embodiment of an interferometric modulator.

Figure 7E is a cross-sectional view of yet another alternative embodiment of an interferometric modulator.

8A-8C are cross-sectional views of interferometric modulators formed on a pre-patterned substrate according to one embodiment.

8D is a cross-sectional view of an interferometric modulator formed on a pre-patterned substrate according to another embodiment.

8E is a cross-sectional view of an interferometric modulator formed on a pre-patterned substrate according to yet another embodiment.

Detailed ways

The following detailed description refers to certain specific embodiments of the invention. However, the invention can be implemented in many different ways. In this description, reference is made to the accompanying drawings, wherein like numerals are used to identify like parts throughout. As will be readily apparent from the following description, the embodiments may be implemented in any device configured to display images, whether in motion (eg, video) or static images (eg, still images), whether textual or pictorial. More specifically, the present invention contemplates that the present invention may be implemented in or associated with numerous electronic devices such as, but not limited to, the following: mobile phones, wireless devices, personal data assistants (PDAs), handheld Computers or laptops, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, watches, clocks, calculators, TV monitors, flat panel displays, computer monitors, automotive displays (such as odometers displays, etc.), cockpit controls and/or displays, camera scene displays (such as a vehicle’s rear-view camera display), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (such as a piece of jewelry on the image display). MEMS devices of similar structure to the MESE devices described herein may also be used in non-display applications, such as in electronic switching devices.

An embodiment of an interferometric modulator display including an interferometric MEMS display element is illustrated in FIG. 1 . In these devices, pixels are in either a light or a dark state. In the bright ("on" or "Open") state, the display element reflects a substantial portion of incident visible light to the user. When in the dark ("off" or "Closed") state, the display element reflects little incident visible light to the user. Depending on the different embodiments, the light reflective properties of the "on" and "off" states may be reversed. MEMS pixels can be configured to reflect primarily at selected colors to enable color displays in addition to black and white.

1 is an isometric view of two adjacent pixels in a series of pixels in a visual display, where each pixel includes a MEMS interferometric modulator. In some embodiments, an interferometric modulator display includes a row/column array of interferometric modulators. Each interferometric modulator includes a pair of reflective layers positioned a variable and controllable distance from each other to form an optical resonant cavity having at least one variable dimension. In one embodiment, one of the reflective layers is movable between two positions. In a first position, referred to herein as the relaxed position, the movable layer is positioned at a relatively large distance from a fixed partially reflective layer. In a second position, referred to herein as the activated position, the movable reflective layer is positioned more closely adjacent the partially reflective layer. Depending on the position of the movable reflective layer, incident light reflected from the two layers interferes constructively or destructively, resulting in an overall reflective or non-reflective state for each pixel.

The pixel array portion depicted in FIG. 1 includes two adjacent interferometric modulators 12a and 12b. In the interferometric modulator 12a on the left, a movable reflective layer 14a is shown in a relaxed position a predetermined distance from an optical stack 16a including a partially reflective layer. In the interferometric modulator 12b on the right, a movable reflective layer 14b is shown at an activated position near the optical stack 16b.

The optical stacks 16a and 16b referred to herein (collectively referred to as the optical stack 16) are generally composed of several fused layers, which may include electrode layers such as indium tin oxide (ITO), partially reflective layers such as chrome, and transparent dielectrics. Optical stack 16 is thus conductive, partially transparent, and partially reflective, and may be made, for example, by depositing one or more of the above-described layers onto transparent substrate 20 . In certain embodiments, the layers are patterned into parallel strips, and may form row electrodes in a display device, as will be described further below. The movable reflective layers 14a, 14b may be formed as a series of parallel layers consisting of one or more deposited metal layers deposited on top of the pillars 18 (orthogonal to the row electrodes 16a, 16b) and an intermediate sacrificial material deposited between the pillars 18. Bands. After the sacrificial material is etched away, the movable reflective layer 14a, 14b is separated from the optical stack 16a, 16b by a defined air gap 19 . A highly conductive and reflective material such as aluminum can be used for the reflective layer 14, and these strips can form column electrodes in a display device.

When no voltage is applied, the cavity 19 remains between the movable reflective layer 14a and the optical stack 16a, wherein the movable reflective layer 14a is in a mechanically relaxed state, as shown by the pixel 12a in FIG. 1 . However, after a potential 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 these electrodes together. If the voltage is high enough, the movable reflective layer 14 is deformed and forced against the optical stack 16 . A dielectric layer (not shown in this figure) within optical stack 16 prevents shorting and controls the separation distance between layers 14 and 16, as shown in pixel 12b on the right in FIG. The behavior is the same regardless of the polarity of the applied potential difference. It can be seen that the row/column activation that controls the state of reflective and non-reflective pixels is similar in many respects to the row/column activation used in conventional LCD and other display technologies.

2-5B illustrate one example process and system for using an array of interferometric modulators in a display application.

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Power 

或任何专用微处理器，例如数字信号处理器、微控制器或可编程门阵列。按照业内惯例，可将处理器21配置成执行一个或多个软件模块。除执行一操作系统外，还可将该处理器配置成执行一个或多个软件应用程序，包括网页浏览器、电话应用程序、电子邮件程序或任何其他软件应用程序。FIG. 2 is a system block diagram illustrating one embodiment of an electronic device that may embody aspects of the invention. In this exemplary embodiment, the electronic device includes a processor 21, which may be any general-purpose single-chip or multi-chip microprocessor, such as ARM,

Pentium

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Pro, 8051,

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Or any special purpose microprocessor such as a digital signal processor, microcontroller or programmable gate array. Processor 21 may be configured to execute one or more software modules, as is customary in the industry. In addition to executing an operating system, the processor may also be configured to execute one or more software applications, including web browsers, telephony applications, email programs, or any other software application.

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-sectional view of the array shown in FIG. 1 is shown at line 1-1 in FIG. 2 . For MEMS interferometric modulators, the row/column activation protocol can take advantage of the hysteresis properties of these devices shown in FIG. 3 . It may require, for example, a 10 volt potential difference to deform a movable layer from a relaxed state to an activated state. However, when the voltage is lowered from this value, the movable layer will maintain its state when the voltage drops back below 10 volts. In the exemplary embodiment shown in Figure 3, the movable layer does not fully relax until the voltage drops below 2 volts. Thus, in the example shown in Figure 3, there is a voltage range of approximately 3 to 7 volts within which there is a window of applied voltage within which the device is stable in the relaxed or actuated state. This is referred to herein as the "hysteresis window" or "stability window". For a display array with the hysteresis characteristic shown in Figure 3, the row/column activation protocol can be designed to apply a voltage difference of about 10 volts to the pixels in the selected row to be activated during row gating, and Relaxed pixels have a voltage difference close to 0 volts applied. After gating, a steady state voltage difference of about 5 volts is applied to the pixel to keep it in whatever state the row was gated to be in. In this example, after being written to, each pixel sees a potential difference within a "stability window" of 3-7 volts. This characteristic makes the pixel design shown in FIG. 1 stable in a pre-existing actuated or relaxed state under the same applied voltage conditions. Since each pixel of the interferometric modulator, whether in the actuated or relaxed state, is essentially a capacitor formed by the fixed reflective layer and the moving reflective layer, the stable state can be maintained within the hysteresis window Under a certain voltage, it consumes almost no power. If the applied potential is fixed, substantially no current flows into the pixel.

In a typical application, a display frame may be formed by defining a set of column electrodes according to the desired set of actuated pixels in the first row. Thereafter, a row pulse is applied to the electrodes of row 1, thereby activating the pixels corresponding to the determined column lines. Thereafter, the determined set of column electrodes is changed to correspond to the desired set of actuated pixels in the second row. Thereafter, a pulse is applied to the electrode of row 2, thereby activating the corresponding pixel in row 2 according to the determined column electrode. The pixels of row 1 are not affected by the pulse of row 2 and thus maintain the state they were set to during the pulse of row 1. The above steps can be repeated in a sequential fashion for the entire series of rows to form the frame. Typically, the frames are refreshed and/or updated with new display data by continuously repeating the process at some desired number of frames per second. There are also a wide variety of protocols for driving the row and column electrodes of an array of pixels to form a display frame that are well known and can be used with the present invention.

4, 5A and 5B illustrate one possible activation protocol for forming a display frame on the 3x3 array shown in FIG. FIG. 4 shows a set of possible row and column voltage levels that may be used for a pixel having the hysteresis curve shown in FIG. 3 . In the embodiment of FIG. 4, activating a pixel includes setting the corresponding column to -V _bias and setting the corresponding row to +ΔV, which may correspond to -5 volts and +5 volts, respectively. Relaxing the pixel is accomplished by setting the corresponding column to +V _bias and the corresponding row to the same +ΔV to create a 0 volt potential difference across the pixel. In those rows where the row voltage remains at 0 volts, the pixel is stable in whatever state it was originally in, regardless of whether the column is _biased at +V or _-V . As also shown in FIG. 4, it should be appreciated that voltages of opposite polarity to those described above may also be used, for example, activating a pixel may involve setting the corresponding column to +V _bias and setting the corresponding set to -ΔV. In this embodiment, releasing the pixel is accomplished by setting the corresponding column to a -V _bias and the corresponding row to the same -ΔV, creating a potential difference of 0 volts across the pixel. As also shown in FIG. 4, it should be appreciated that voltages of opposite polarity to those described above may also be used, for example, activating a pixel may involve setting the corresponding column to +V _bias and setting the corresponding set to -ΔV. In this embodiment, releasing the pixel is accomplished by setting the corresponding column to a -V _bias and the corresponding row to the same -ΔV, creating a potential difference of 0 volts across the pixel.

Fig. 5B is a timing diagram showing a series of row and column signals applied to the 3x3 array shown in Fig. 2, which will result in the display arrangement shown in Fig. 5A, wherein the actuated pixels are non-reflective. Prior to writing the frame shown in Figure 5A, the pixels can be in any state, and in this example, all rows are at 0 volts and all columns are at +5 volts. At these applied voltages, all pixels are stable in their existing actuated or relaxed states.

In the frame shown in FIG. 5A, pixels (1,1), (1,2), (2,2), (3,2) and (3,3) are activated. To achieve this, set columns 1 and 2 to -5 volts and column 3 to +5 volts during a "line time" in row 1. This does not change the state of any pixels, as all pixels remain within the 3-7 volt stability window. Thereafter, row 1 is strobed with a pulse that rises from 0 volts to 5 volts and then falls back to 0 volts. Pixels (1,1) and (1,2) are thereby activated and pixel (1,3) is relaxed. No other pixels in the array are affected. To set row 2 to the desired state, set column 2 to -5 volts, and set columns 1 and 3 to +5 volts. Thereafter, the same strobe applied to row 2 will activate pixel (2,2) and relax pixels (2,1) and (2,3). Likewise, no other pixels in the array are affected. Similarly, set row 3 by setting columns 2 and 3 to -5 volts, and setting column 1 to +5 volts. The row 3 strobe pulse sets the row 3 pixels to the state shown in Figure 5A. After writing a frame, the row potentials are 0, while the column potentials can remain at +5 or -5 volts, and thereafter the display will stabilize in the arrangement shown in Figure 5A. It should be appreciated that the same procedure can be used with arrays of tens or hundreds of rows and columns. It should also be understood that the timing, sequence, and levels of voltages used to perform row and column activation can vary widely within the general principles outlined above, and that the above examples are exemplary only, and that either activation voltage Methods are used with the systems and methods described herein.

6A and 6B are system block diagrams illustrating one embodiment of a display device 40 . Display device 40 may be, for example, a cellular or mobile telephone. However, the same components of display device 40 and slight variations thereof are also illustrative of various types of display devices, such as televisions and portable media players.

The display device 40 includes a housing 41 , a display 30 , an antenna 43 , a speaker 44 , an input device 48 , and a microphone 46 . Housing 41 is typically made by any of a number of manufacturing processes well known to those skilled in the art, including injection molding and vacuum forming. Additionally, housing 41 may be made from any of a number of materials including, but not limited to, plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment, the housing 41 includes a detachable portion (not shown) that is interchangeable with other detachable portions of a different color or containing different logos, pictures or symbols.

Display 30 of example display device 40 may be any of a wide variety of displays, including the bi-stable displays described herein. In other embodiments, display 30 comprises a flat panel display, such as the plasma display, EL, OLED, STN LCD or TFT LCD described above, or a non-flat panel display, such as a CRT or TFT LCD, as is well known to those skilled in the art. Other picture tube devices. However, for ease of illustration of the present embodiment, display 30 comprises an interferometric modulator display as described herein.

Components of an embodiment of an example display device 40 are schematically illustrated in FIG. 6B. The illustrated example display device 40 includes a housing 41 and may include other components at least partially enclosed therein. For example, in one embodiment, the exemplary display device 40 includes a network interface 27 including an antenna 43 coupled to a transceiver 47 . Transceiver 47 is connected to processor 21 , which in turn is connected to conditioning hardware 52 . Conditioning hardware 52 may be configured to condition a signal (eg, filter a signal). The adjustment software 52 is connected to a speaker 45 and a microphone 46 . The processor 21 is also connected to an input device 48 and a drive controller 29 . The driver controller 29 is coupled to a frame buffer 28 and to the array driver 22 , and the array driver 22 is further coupled to a display array 30 . A power supply 50 provides power to all components as required by the design of the particular exemplary display device 40 .

The network interface 27 includes an antenna 43 and a transceiver 47 to enable the example display device 40 to communicate with one or more devices over a network. In an embodiment, the network interface 27 may also have some processing functions to reduce the requirements on the processor 21 . The antenna 43 is any antenna known to those skilled in the art for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to IEEE 802.11 standards, 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 or other known signals for communicating in wireless mobile telephone networks. The transceiver 47 pre-processes the signal received from the antenna 43 so that it can be received and further processed by the processor 21 . Transceiver 47 also processes signals received from processor 21 so that they may be transmitted from exemplary display device 40 via antenna 43 .

In an alternative embodiment, a receiver may be used instead of transceiver 47 . In yet another alternative embodiment, network interface 27 may be replaced by an image source that may store or generate image data to be sent to processor 21 . For example, the image source may be a digital video disc (DVD) or a hard drive containing image data, or a software module that generates image data.

Processor 21 generally controls the overall operation of exemplary display device 40 . Processor 21 receives data, such as compressed image data, from network interface 27 or an image source, and processes the data into raw image data or a format that is easily processed into raw image data. Then, the processor 21 sends the processed data to the drive controller 29 or to the frame buffer 28 for storage. Raw data generally refers to information that identifies image features at each location within an image. For example, these image characteristics may include color, saturation, and grayscale.

In one embodiment, the processor 21 includes a microcontroller, CPU, or logic unit for controlling the operation of the exemplary display device 40 . Conditioning hardware 52 typically includes amplifiers and filters for transmitting signals to speaker 45 and receiving signals from microphone 46 . Conditioning hardware 52 may be a discrete component within example display device 40, or may be incorporated within processor 21 or other components.

The drive controller 29 obtains the raw image data generated by the processor 21 directly from the processor 21 or from the frame buffer 28 and properly reformats the raw image data for high-speed transmission to the array driver 22 . Specifically, drive controller 29 reformats the raw image data into a data stream having a raster-like format such that it has a temporal order suitable for scanning display array 30 . Then, the drive controller 29 sends the formatted information to the array driver 22 . Although a driver controller 29 (such as an LCD controller) is often associated with the system processor 21 as a separate integrated circuit (IC), these controllers can be implemented in many ways. It may be embedded in the processor 21 as hardware, embedded in the processor 21 as software, or fully integrated with the array driver 22 in hardware.

Typically, array driver 22 receives formatted information from driver controller 29 and reformats the video data into a set of parallel waveforms that are applied to hundreds of pixels from the x-y pixel matrix of the display many times per second. and sometimes thousands of leads.

In one embodiment, driver controller 29, array driver 22, and display array 30 are suitable for any type of display described herein. For example, in one embodiment, drive controller 29 is a conventional display controller or a bi-stable display controller (eg, an interferometric modulator controller). In another embodiment, the array driver 22 is a conventional driver or a bi-stable display driver (eg, an interferometric modulator display). In one embodiment, a driver controller 29 is integrated with the array driver 22 . Such embodiments are common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, the display array 30 is a typical display array or a bi-stable display array (eg, a display including an array of interferometric modulators).

Input device 48 enables a user to control the operation of example display device 40 . In one embodiment, the 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 sensitive or heat sensitive film. In one embodiment, the microphone 46 is an input device for the exemplary display device 40 . Voice commands may be provided by the user to control the operation of the exemplary display device 40 when data is entered into the device using the microphone 46 .

Power supply 50 may include a wide variety of energy storage devices, as are well known in the art. For example, in one embodiment, the power source 50 is a rechargeable battery, such as a nickel-cadmium battery or a lithium-ion battery. In another embodiment, the power source 50 is a renewable energy source, capacitor or solar cell, including a plastic solar cell and solar cell paint. In another embodiment, the power supply 50 is configured to receive power from a wall outlet.

In certain implementations, as described above, control programmability resides in a drive controller that may be located in several places in the electronic display system. In some cases, control programmability resides in array driver 22 . Those skilled in the art will appreciate that the above-described optimizations may be implemented in any number of hardware and/or software components and in different configurations.

The detailed structure of an interferometric modulator operating according to the principles described above can vary widely. For example, Figures 7A-7E illustrate five different embodiments of the movable reflective layer 14 and its supporting structures. FIG. 7A is a cross-sectional view of the embodiment shown in FIG. 1 , wherein a strip 14 of metallic material is deposited on orthogonally extending supports 18 . In FIG. 7B the movable reflective layer 14 is attached to the support on tethers 32 only at the corners. In FIG. 7C, the movable reflective layer 14 is suspended from a deformable layer 34, which may comprise a flexible metal. The deformable layer 34 is directly or indirectly attached to the substrate 20 around the perimeter of the deformable layer 34 . These connections are referred to herein as support columns. The embodiment shown in FIG. 7D has a support post plug 42 on which the deformable layer 34 is located. As shown in FIGS. 7A-7C , the movable reflective layer 14 remains suspended above the cavity, but the deformable layer 34 does not form support posts by filling the holes between the deformable layer 34 and the optical stack 16 . Instead, the support posts are formed from the planarized material used to form the support post plugs 42 . The embodiment shown in Figure 7E is based on the embodiment shown in Figure 7D, but may also be modified for use with any of the embodiments shown in Figures 7A-7C, as well as other embodiments not shown. In the embodiment shown in FIG. 7E , an additional layer of metal or other conductive material has been used to form a bus structure 44 . This enables signals to be routed along the backside of the interferometric modulator, eliminating several electrodes that would otherwise have to be formed on the substrate 20 .

In embodiments such as those shown in Figure 7, the interferometric modulators are used as a direct-view device, where the image is viewed from the front side of the transparent substrate 20 (the side opposite the side on which the modulators are disposed). In these embodiments, reflective layer 14 optically shields portions of the interferometric modulator on the reflective layer side opposite substrate 20 , including deformable layer 34 . This enables configuration and manipulation of masked areas without adversely affecting image quality. Such shielding allows for the bus structure 44 in Figure 7E, which would provide the ability to separate the optical properties of the modulator from the electromechanical properties of the modulator, such as addressing and the movement caused by addressing. Such a separable modulator architecture enables the structural design and materials used for the electromechanical aspects of the modulator and for the optical aspects of the modulator to be selected and function independently of each other. Moreover, the embodiment shown in FIGS. 7C-7E has the additional advantage of decoupling the optical properties of the reflective layer 14 from its mechanical properties, which is implemented by the deformable layer 34 . This allows the structural design and used materials of the reflective layer 14 to be optimized in terms of optical properties, and the structural design and used materials of the deformable layer 34 to be optimized in terms of desired mechanical properties.

As discussed above, the interferometric modulator is configured to reflect light passing through the transparent substrate and includes moving parts such as movable mirrors 14a, 14b. Therefore, to enable movement of these moving parts, an air gap or cavity is preferably formed to allow movement of the mechanical parts of the interferometric modulator, such as the movable mirrors 14a, 14b.

8A-8C are cross-sectional views of interferometric modulators formed on a pre-patterned substrate according to one embodiment. It has been found that when using a pre-patterned substrate, the steps involved in fabricating an interferometric modulator with the functions described above can be adapted to a very cost-effective fabrication technique. Figures 8A-8C illustrate one embodiment of such a method, which would result in an interferometric modulator viewed from the side opposite to the interferometric modulator described above with reference to Figures 1-7E. Depending on the end application of the device, it may sometimes be advantageous to make a display viewed through the substrate, and sometimes it may be preferable to make a display viewed through the deposited layers of the interferometric modulator. Thus, for this design, there is no need to use a transparent substrate (such as transparent substrate 20 shown in FIGS. 7A-7E ) on which the interferometric modulators are formed. The pre-patterned substrate can thus be both opaque and transparent. In the illustrated embodiment shown in Figures 8A-8C, the pre-patterned substrate is preferably opaque, which enables selection of materials that facilitate embossing.

According to the embodiment shown in FIGS. 8A-8C , an interferometric modulator is formed on a pre-patterned substrate 505 . A substrate 505 in which trenches 507 are formed is preferably covered with a mirror layer to form a lower electrode (semi-reflective or reflective member) 502, which will serve as the pinned layer as described above.

Substrate 505 may be formed from a preferably opaque polymeric material having a series of embossed, suitably spaced grooves or grooves 507 extending in one direction along the surface of the substrate. These grooves 507 can be embossed using known techniques using a variety of conventional materials, preferably having a reentrant profile with tapered sides, as shown in Figures 8A-8C. In a preferred embodiment, a substrate 505 formed of composite material is embossed, stamped, ablated, molded, or mechanically imprinted with grooves or grooves, and then baked to obtain the reentrant profile . Those skilled in the art will appreciate that such a composite material is preferably formed from different materials in different layers and that after stamping or embossing the substrate, baking will cause different thermal expansions in these different layers. In the illustrated embodiment, the top layer has a higher coefficient of thermal expansion, causing expansion into the groove 507 . Although a reentrant profile is preferred, those skilled in the art will appreciate that the grooves 507 may have other shapes (e.g., vertical walls) as long as these grooves are deposited on the top surface of the substrate 505 as described in more detail below. It is sufficient to form a breakpoint in the above material. It should be appreciated that formation in the substrate 505 may also be by techniques other than imprinting, such as etching, for example. However, embossing or stamping is preferred as it is an inexpensive process.

When depositing material on such a surface structure, some material will deposit and precipitate into the grooves 507 and some material will deposit and precipitate on the top surface of the substrate 505 between the grooves 507 . The material is preferably deposited by conventional deposition techniques, such as by some form of sputtering, physical vapor deposition and chemical vapor deposition (CVD). As shown in FIGS. 8A-8C , the presence of grooves 507 creates discontinuities or discontinuities in the deposited layer on the top surface of substrate 505 . In this way, the lower layers 502, 508, 510 of the interferometric modulators are deposited without using conventional photolithography and etching steps. In this embodiment, in effect, the first set of masks forming the structures shown in FIGS. 7A-7E are incorporated into the substrate 505 itself, and in fact can be replaced by an economical imprint process for the initial electrode pattern. cover up. According to this embodiment, the first steps in the fabrication of the interferometric modulator structure are thus the deposition of the lower electrode 501 , a dielectric material 508 , and a layer of sacrificial material 510 . The deposited layers of lower electrode 502 , dielectric material 508 and sacrificial material 510 are thus formed in rows or strips on the top surface of substrate 505 . The stripe structure is naturally produced due to the presence of the embossed grooves 507 .

The lower electrode 502 is preferably formed of aluminum. In other embodiments, the lower electrode 502 may comprise other highly reflective metals such as, for example, silver (Ag) or gold (Au). Alternatively, the lower electrode 502 may be a metal stack configured to provide appropriate optical and mechanical properties.

A dielectric layer 508 is preferably deposited on the lower electrode 502 . In a preferred embodiment, the dielectric material is silicon dioxide (SiO ₂ ). A sacrificial layer 510 is preferably deposited (and thereafter removed) over the structure to form an optical resonant cavity between the lower electrode 502 and an upper electrode or reflective member 506 that will Deposited over sacrificial layer 510 to form a movable layer, as shown in FIG. 8B. In the illustrated embodiment, the sacrificial layer 510 includes silicon (Si). In other embodiments, the sacrificial layer 510 may be formed of molybdenum (Mo), tungsten (W) or titanium (Ti). All of these sacrificial materials can be etched selectively with respect to exposed dielectric and electrode materials, but those skilled in the art will readily appreciate that other sacrificial materials (such as photoresist) can also be combined with other selective etch chemistries. use together.

As shown in FIG. 8B, in this embodiment, fabrication of the interferometric modulator structure continues by filling the area between the trench 507 and the previously deposited structure. Such filling can be performed by a number of conventional deposition/patterning/etch steps or by an etch-back process such as, for example, a chemical mechanical polishing (CMP) planarization step.

Orthogonal upper electrode strips 506 are preferably deposited over the sacrificial layer 510, followed by deposition of strips of a second or upper sacrificial material 520 separated by pillars 522. The upper electrodes 506 are deposited as strips in rows orthogonal to the lower electrodes 502 to form the row/column array described above. The upper electrode 506 and the sacrificial material 520 may preferably be deposited in strips in their desired pattern using a shadow mask deposition technique. The post 522 is formed of an insulating material, preferably a polymer or a dielectric material.

A thin (preferably 50-100 Angstroms) semi-reflective layer 530 is then deposited on top of the upper sacrificial layer 520, preferably. In a preferred embodiment, the semi-reflective layer 530 is chromium. As shown in FIG. 8B, a transparent material or viewing feature 535 is deposited over the semi-reflective layer 530 to provide additional mechanical and structural integrity to the semi-reflective layer 530—after removal of the sacrificial layers 510, 520, the semi-reflective Reactive layer 530 is typically too thin to support itself. Those skilled in the art will appreciate that the transparent substrate 535 assumes mechanical functions and acts as a means through which a display is made and light is transmitted through. The transparent substrate 535 may be formed of a solid inorganic material such as oxide. In another embodiment, the transparent substrate 535 may be formed of a transparent polymer. The semi-reflective layer 530 and transparent substrate are preferably deposited by conventional deposition techniques such as sputtering, PVD, and CVD.

Transparent material 535 and semi-reflective layer 530 are preferably etched with openings or holes (not shown) so that the sacrificial material of layers 510 and 520 can be reached by etching gases used to remove the sacrificial layer. Alternatively, the transparent material 535 may be pre-patterned with pre-etched or embossed openings or holes. It will be appreciated that the interferometric modulators are sealed and protected from the environment surrounding the package housing the interferometric modulators as part of the overall packaging process. Preferably, these holes or openings have a diameter as small as a photolithographic system will allow, and more preferably about 2.4 microns. Those skilled in the art will appreciate that the size, spacing and number of openings will affect the removal rate of the sacrificial layers 510, 520.

The sacrificial layers 510 , 520 are preferably removed using a selective gas etch process to form an optical cavity around the movable electrode 506 . The sacrificial layers 510, 520 may be removed using standard etching techniques. The specific gas etch process will depend on the material to be removed. For example, xenon difluoride (XeF ₂ ) can be used as the release gas to remove the silicon sacrificial layer. It should be appreciated that the etch process is a selective etch process that does not etch any dielectric material, semi-reflective material, or electrode material.

The final structure of the interferometric modulator is shown in FIG. 8C , where there is an optical cavity surrounding the moving electrode 506 . With the semi-reflective layer 530 on top, the interferometric modulator is viewed through the transparent substrate 535 from the side of the respective deposited layer in the direction of arrow 540, as shown in Figure 8C.

In the embodiment shown in FIGS. 8A-8C , it will be appreciated that the movable layer 506 of the interferometric modulator is adjacent to the transparent substrate 535 and the fixed layer 502 is formed below the movable layer 506 so that the movable layer 506 can move in the The structure moves within the optical cavity, as shown in Figure 8C.

Those skilled in the art will appreciate that in the embodiment shown in Figure 8D, the semi-reflective layer 530 is preferably chrome and can be supplemented with a transparent electrode, preferably an ITO layer and used as an electrode. As shown in FIG. 8D , ITO layer 532 is interposed between transparent substrate 535 and chrome layer 530 . The ITO-Chromium bilayer structure eliminates the need to use the lower electrode 502 and dielectric 508 in the embodiment shown in Figures 8A-8C. In this embodiment, a dielectric layer 508 is interposed between the chrome 530 and the upper cavity. Those skilled in the art will understand that a first sacrificial layer (not shown) is deposited on the pre-patterned transparent substrate 505 and then removed to form a lower cavity 560, and a second sacrificial layer (not shown) is deposited over electrode 506 to form upper cavity 565 . As shown in FIG. 8D , electrode 506 is deposited on pre-patterned substrate 505 to form electrode stripes on the top surface of substrate 505 with discontinuities in electrode 506 formed by deposition over trenches 507 point.

As described above, transparent pre-patterned substrates made from transparent materials such as polymers can be used to form interferometric modulators similar to those shown in Figures 7A-7E. In such an interferometric modulator, as shown in FIG. 8E , unlike the embodiment shown in FIGS. 8A-8C , a transparent pre-patterned substrate 580 transmits light and passes A pre-patterned substrate 580 is viewed. Those skilled in the art will appreciate that the process for making such an interferometric modulator is similar to the method described above with reference to Figures 8A-8C, but the electrode structure would be reversed. The structure would be similar to that shown in FIGS. 7A-7E , but the first few patterning and etching steps used to form the rows are eliminated by depositing the first few layers of the rows above the trenches 507 .

As shown in Figure 8E, a semireflective-ITO bilayer 530, 532 is deposited over a substrate 580 to form electrode stripes. A dielectric layer 508 is deposited over the semireflective-ITO bilayers 530,532. Then, a first sacrificial layer (not shown) is deposited and then removed to form a lower cavity 560 . Movable electrodes 506 are deposited in orthogonal stripes on top of the first sacrificial layer. A second sacrificial layer (not shown) is deposited over the movable electrode 506 and then removed to form the upper cavity 565 . As shown in Figure 8E, the movable electrode 506 is in a collapsed state. To complete the structure, a deformable layer 570 is formed over the upper cavity 565 .

While the foregoing detailed description has shown, described, and pointed out novel features of the present invention that are applicable to various embodiments, it should be understood that various omissions in form and detail of the devices or processes shown, Substitutions and changes are made without departing from the spirit of the invention. It is to be understood that the invention may be implemented in a form that does not provide all of the features and advantages described herein, because some features may be used or practiced independently of other features.

Claims (48)

1, a kind of method of making MEMS devices, it comprises:

Substrate is provided, and it has a plurality of grooves in the end face of described substrate;

Deposition first electrode layer enters in the described groove on the described end face of described substrate, and wherein said first electrode layer that deposits is discontinuous between described groove and described end face;

On described first electrode layer, form second electrode; And

Form first cavity between first electrode layer on the described substrate and described second electrode described being formed at.

2, the method for claim 1, it further comprises makes described first electrode layer and described second electrode insulation.

3, method as claimed in claim 2, wherein isolation step is included in deposition of dielectric materials on described first electrode layer.

4, method as claimed in claim 3, wherein by before forming described second electrode in sacrificial material on the described dielectric material and remove described expendable material after forming described second electrode and form described first cavity.

5, the method for claim 1, it further is included in and forms second cavity between described second electrode and the semi-reflective layer.

6, method as claimed in claim 5 wherein forms described second cavity and comprises: removed described expendable material in sacrificial material on described second electrode and after forming described semi-reflective layer before forming described semi-reflective layer.

7, method as claimed in claim 5, wherein said semi-reflective layer comprises chromium.

8, method as claimed in claim 5, it further is included in deposit transparent material on the described semi-reflective layer.

9, method as claimed in claim 8 wherein forms described first cavity and comprises: removed described expendable material in sacrificial material on the described dielectric material and after forming described second electrode before forming described second electrode.

10, method as claimed in claim 9, wherein before removing described first sacrifice layer, described transparent material and semi-reflective layer etching have perforate.

11, the method for claim 1 wherein provides step to be included in the described groove of impression in the described substrate.

12, the method for claim 1 wherein provides step to be included in the described groove of ablating in the described substrate.

13, the method for claim 1 wherein provides step to comprise by molding process and form described groove in described substrate.

14, the method for claim 1, the uncontinuity of wherein said first electrode layer at described groove place makes the described first electrode layer patterning.

15, the method for claim 1, wherein said MEMS devices are interferometric modulator.

16, a kind of MEMS devices that forms by the method for claim 1.

17, a kind of display device, it comprises:

Through the substrate of impression, it has a plurality of grooves in the end face that is formed at described substrate;

First electrode layer, it is formed on the described end face of described substrate and enters in described a plurality of groove, and described first electrode layer is discontinuous between described a plurality of grooves and described end face; And

Second electrode, wherein said second electrode is formed on described first electrode layer, and wherein said first electrode layer and described second electrode separate by first cavity.

18, display device as claimed in claim 17, wherein said first electrode layer and described second electrode are by being deposited on dielectric material on described first electrode layer and mutually insulated.

19, display device as claimed in claim 17, each in wherein said a plurality of grooves all has reentrant profile.

20, display device as claimed in claim 17, wherein said substrate is opaque.

21, display device as claimed in claim 17, wherein said first electrode layer forms first electrode with the described second electrode quadrature.

22, display device as claimed in claim 17, it is movably that wherein said second electrode is configured to.

23, display device as claimed in claim 17, it further comprises: semi-reflective layer, it separates by second cavity and described second electrode; And be formed at transparent material on the described semi-reflective layer.

24, display device as claimed in claim 23 is formed with a plurality of holes in the wherein said transparent material.

25, display device as claimed in claim 17, it further comprises:

At least one electric connection in the processor, itself and described first electrode layer and described second electrode, described processor is configured to image data processing; And

Memory storage, itself and described processor electric connection.

26, display device as claimed in claim 25, it further comprises driving circuit, described driving circuit is configured in described first electrode layer and described second electrode at least one and sends at least one signal.

27, display device as claimed in claim 26, it further comprises controller, described controller is configured at least a portion of described view data is sent to described driving circuit.

28, display device as claimed in claim 25, it further comprises image source module, described image source module is configured to described image data transmission to described processor.

29, display device as claimed in claim 28, wherein said image source module comprise receiver, transceiver, and transmitter at least one.

30, display device as claimed in claim 25, it further comprises input media, described input media is configured to receive the input data and described input data is sent to described processor.

31, a kind of method that forms MEMS devices, it comprises:

Substrate with end face is provided, wherein in described end face, forms a plurality of grooves;

At least one layer of deposition on described substrate, wherein said at least one layer comprises first conductive material and discontinuous at described groove and described end face place, thereby forms each row of described layer between the described groove on the described end face; And

Deposit second conductive material, described first conductive material on wherein said second conductive material and the described end face is oriented orthogonally to.

32, method as claimed in claim 31, wherein said at least one layer further comprises dielectric layer and expendable material.

33, method as claimed in claim 31, it further is included in and forms first cavity between described first conductive material and described second conductive material.

34, method as claimed in claim 32, it further is included on described second conductive material and deposits semi-reflective layer, and wherein said semi-reflective layer and described second conductive material separate by cavity.

35, method as claimed in claim 34 wherein forms described cavity between described chromium layer and described second conductive material by removing expendable material between described semi-reflective layer and described second conductive material.

36, method as claimed in claim 31 wherein provides described a plurality of groove to comprise in described end face and impresses.

37, method as claimed in claim 36, it cures described substrate after further being included in impression, provides reentrant profile to give in the described groove each, and wherein said substrate is formed by compound substance.

38, method as claimed in claim 37, the top layer of wherein said compound substance have the thermal expansivity than the bottom floor height of described compound substance.

39, a kind of display device, it comprises:

Substrate, it has a plurality of grooves in the end face of described substrate;

Be used for catoptrical first reflecting member, described first reflecting member is formed on the described end face of described substrate and enters in the described groove, and described first reflecting member is discontinuous between described groove and described end face place; And

Be used for catoptrical second reflecting member, wherein said second reflecting member is formed on described first reflecting member, and wherein said first reflecting member and described second reflecting member separate by first partition member.

40, display device as claimed in claim 39, it further comprises:

The half reflection member, it separates by second partition member and described second reflecting member; And

The member of watching that is used for transmitted light, the described member of watching is formed on the described half reflection member.

41, display device as claimed in claim 39, the shape of wherein said groove make that described first reflecting member is discontinuous on the sidewall of described groove.

42, display device as claimed in claim 39, described first reflecting member on the described end face of wherein said substrate member form each row of described first reflecting member on described end face.

43, display device as claimed in claim 39, wherein said second reflecting member is second reflection horizon, it hangs on the connector that is attached to mechanical layer.

44, display device as claimed in claim 39, it further comprises the insulating component between described first reflecting member and described second reflecting member, wherein said insulating component is the dielectric layer that is positioned on described first reflecting member.

46, a kind of method of operation display device, it comprises:

Be provided at the substrate that has a plurality of grooves in its end face, wherein at least one first electrode layer is formed on the described end face of described substrate and enters in the described groove, and wherein said first electrode layer is discontinuous between described groove and described end face, and wherein said first electrode layer separates by the cavity and second electrode, and described second electrode is formed on the described cavity; And

In described cavity, move described second electrode.

47, method as claimed in claim 46 wherein moves described second electrode and is included in slack position and is subjected to move between the active position described second electrode.

48, method as claimed in claim 46 wherein moves described second electrode and can change described first electrode layer and described second distance between electrodes.

49, method as claimed in claim 46, wherein mobile described second electrode is included between described first electrode layer and described second electrode and applies electrostatic attraction.

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