Process control monitors for interferometric modulators
Process control monitors are disclosed that are produced using at least some of the same process steps used to manufacture a MEMS device. Analysis of the process control monitors can provide information regarding properties of the MEMS device and components or sub-components in the device. This information can be used to identify errors in processing or to optimize the MEMS device. In some embodiments, analysis of the process control monitors may utilize optical measurements.
1 . A method of obtaining information regarding manufacturing processes used to manufacture a micro-electro-mechanical system (MEMS), comprising:
forming at least one MEMS structure on a first side of a substrate through a series of deposition and patterning steps;
simultaneously forming at least one process control monitor on the first side of the substrate utilizing the series of deposition and patterning steps, wherein the process control monitor has at least one structural difference from the MEMS structure; and
detecting light reflected from the process control monitor from a second side of the substrate opposite the first side, whereby the detected light provides a characteristic of at least one material deposited or removed during the deposition and patterning steps.
2 . The method of claim 1 , wherein the MEMS structure is an interferometric modulator.
3 . The method of claim 1 , wherein the process control monitor is formed using the same sequence of deposition and patterning steps used to form the MEMS structure.
4 . The method of claim 1 , wherein after forming the process control monitor and the MEMS structure, the process control monitor comprises a layer of material not present in the MEMS structure.
5 . The method of claim 1 , wherein after forming the process control monitor and the MEMS structure, the MEMS structure comprises a layer of material not present in the process control monitor.
6 . The method of claim 1 , wherein after forming the process control monitor and the MEMS structure, the process control monitor comprises the same layers of material as present in the MEMS structure.
7 . The method of claim 1 , wherein said detecting includes measuring the reflected light with a photodetector.
8 . The method of claim 1 , wherein said detecting includes measuring the reflected light with a spectrometer.
9 . The method of claim 1 , wherein said detecting includes measuring the reflected light with a colorimeter.
10 . The method of claim 1 , wherein said detecting includes detecting the reflected light with a camera.
11 . The method of claim 1 , wherein the characteristic of said material deposited or removed includes the thickness of the material.
12 . The method of claim 1 , wherein the characteristic of said material deposited or removed includes the material's index of refraction.
13 . The method of claim 1 , wherein the characteristic of said material deposited or removed includes the material's reflectivity.
14 . A method of monitoring interferometric modulator manufacturing processes, wherein the manufacturing process comprises a series of deposition and patterning steps, the method comprising:
forming a process control monitor using the series of deposition and patterning steps, wherein the process control monitor has at least one structural difference from interferometric modulators formed by the manufacturing process; and
detecting optical reflectance from the process control monitor.
15 . The method of claim 14 , wherein optical reflectance is detected from a side of the process control monitor where the deposition and patterning steps are applied.
16 . The method of claim 14 , wherein optical reflectance is detected from a side of the process control monitor opposite a side where the deposition and patterning steps are applied.
17 . The method of claim 14 , wherein the process control monitor is formed using the same sequence of deposition and patterning steps used in the manufacturing process.
18 . The method of claim 14 , wherein after forming the process control monitor, the process control monitor comprises a layer of material not present in interferometric modulators formed by the manufacturing process.
19 . The method of claim 14 , wherein after forming the process control monitor, the process control monitor is lacking a layer of material present in interferometric modulators formed by the manufacturing process.
20 . The method of claim 14 , wherein after forming the process control monitor, the process control monitor comprises the same layers of material as present in interferometric modulators formed by the manufacturing process.
21 . The method of claim 14 , wherein the detecting step includes using a photodetector.
22 . The method of claim 14 , wherein the detecting step includes using a spectrometer.
23 . The method of claim 14 , wherein said detecting includes measuring the reflected light with a colorimeter.
24 . The method of claim 14 , wherein said detecting includes detecting the reflected light with a camera.
25 . A process control monitor for use in monitoring interferometric modulator manufacturing processes, wherein the interferometric modulators are adapted for use in a display, the process control monitor manufactured by a process comprising at least one step in common with steps used to manufacture the interferometric modulators adapted for use in the display.
26 . The process control monitor of claim 25 , wherein the at least one step in common includes a deposition step.
27 . The process control monitor of claim 25 , wherein the process control monitor comprises at least one layer of material also present in the interferometric modulators.
28 . The process control monitor of claim 25 , wherein the process control monitor comprises an etalon.
29 . The process control monitor of claim 28 , wherein the etalon comprises:
a layer of partially reflective material;
a layer of substantially totally reflective material; and
one or more dielectric layers positioned between the partially reflective material and the substantially totally reflective material.
30 . The process control monitor of claim 29 , wherein the partially reflective material and the substantially totally reflective material contact the one more dielectric layers.
31 . A wafer, comprising:
one or more reflective display elements adapted for use in a display; and
one or more process control monitors adapted to reflect incident light and thereby provide information regarding processes used to manufacture the one or more reflective display elements.
32 . The process control monitor of claim 31 , wherein the reflective display elements are interferometric modulators.
33 . The process control monitor of claim 31 , wherein at least one of the one or more process control monitors includes an etalon.
34 . The process control monitor of claim 31 , wherein the information regarding manufacturing processes includes information regarding properties of a material deposited during the manufacturing processes.
35 . The process control monitor of claim 34 , wherein the information regarding properties of deposited material includes the material's thickness.
36 . The process control monitor of claim 34 , wherein the information regarding properties of deposited material includes the material's index of refraction.
37 . The process control monitor of claim 34 , wherein the information regarding properties of deposited material includes the material's reflectivity.
38 . The process control monitor of claim 31 , wherein at least one of the one or more process control monitors comprises at least one layer of material also present in the reflective display elements.
39 . A wafer, comprising:
a plurality of first means for reflecting light for use in a display; and
second means for monitoring processes used to manufacture the first means.
40 . The wafer of claim 39 , wherein the first means comprise interferometric modulators.
41 . The wafer of claim 39 , wherein the second means comprises a process control monitor formed on the wafer.
42 . The wafer of claim 39 , wherein the processes monitored include one or more deposition steps.
43 . The wafer of claim 39 , wherein the second means provides information regarding the processes prior to the first means being rendered functional.
44 . The wafer of claim 39 , wherein the second means for monitoring provides information regarding the processes after the second means are rendered functional.
45 . A display, comprising a first wafer that comprises a plurality of interferometric modulators, wherein the first wafer is produced by a process comprising:
forming said plurality of interferometric modulators and at least one process control monitor on a second wafer; and
cutting said second wafer to remove the process control monitor and thereby produce said first wafer.
46 . The display of claim 45 , further comprising:
a processor that is in electrical communication with said display, said processor being configured to process image data;
a memory device in electrical communication with said processor.
47 . The display of claim 46 , further comprising a driver circuit configured to send at least one signal to said display.
48 . The display of claim 47 , further comprising a controller configured to send at least a portion of said image data to said driver circuit.
49 . The display system as recited in claim 46 , further comprising an image source module configured to send said image data to said processor.
50 . The display system as recited in claim 49 , wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.
51 . The display system as recited in claim 46 , further comprising an input device configured to receive input data and to communicate said input data to said processor.
52 . A method of identifying an array of interferometric modulators as suitable for use in a display, wherein the interferometric modulators are manufactured by a process comprising a series of deposition and patterning steps, the method comprising:
forming at least one process control monitor using at least some of the series of deposition. and patterning steps; and
detecting at least one characteristic of the process control monitor.
53 . The method of claim 52 , wherein the characteristic is an optical characteristic.
54 . The method of claim 52 , wherein the characteristic is a height profile of the process control monitor.
55 . An array of interferometric modulators identified as suitable for use as a display by the method of claim 52 .
56 - 176 . (canceled)