System and method for providing thermal compensation for an interferometric modulator display

A system for thermal compensation of a microelectromechanical system (MEMS) device, the system comprising:

• a substrate characterized by a first thermal expansion coefficient;
• a member coupled to the substrate;
• a movable layer characterized by a second thermal expansion coefficient and coupled to the member;
• and
• a film located proximate to the substrate and having a third thermal expansion coefficient less than the first thermal expansion coefficient,
• wherein the film is configured to compensate for expansion of the movable layer with respect to the substrate when the MEMS device is exposed to thermal energy, and wherein the film is positioned below the substrate.

A system for thermal compensation of a microelectromechanical system (MEMS) device, the system comprising:

• a substrate characterized by a first thermal expansion coefficient;
• a member coupled to the substrate;
• a movable layer characterized by a second thermal expansion coefficient and coupled to the member;
• and
• a film located proximate to the substrate and having a third thermal expansion coefficient less than the first thermal expansion coefficient,
• wherein the film is configured to compensate for expansion of the movable layer with respect to the substrate when the MEMS device is exposed to thermal energy, and wherein the film comprises a material having a negative coefficient of thermal expansion.

A system for thermal compensation of a microelectromechanical system (MEMS) device, the system comprising:

• a substrate characterized by a first thermal expansion coefficient;
• a member coupled to the substrate;
• a movable layer characterized by a second thermal expansion coefficient and coupled to the member;
• and
• a film located proximate to the substrate and having a third thermal expansion coefficient less than the first thermal expansion coefficient,
• wherein the film is configured to compensate for expansion of the movable layer with respect to the substrate when the MEMS device is exposed to thermal energy, and wherein the film is at least partially transparent.

A light modulator comprising:

• a substrate;
• a first electrode layer over the substrate;
• a second electrode layer over the substrate;
• a support coupling the substrate to the second electrode layer and forming a cavity between the first electrode layer and the second electrode layer;
• a reflective surface substantially parallel to the first electrode layer and coupled to the second electrode layer;
• and
• a film configured to induce tensile stress in the second electrode layer in response to increased temperature.

A light modulator comprising:

• means for supporting a light modulator;
• means for conducting a first electrical signal;
• means for conducting a second electrical signal;
• means for coupling the means for supporting the light modulator to the means for conducting a second electrical signal and forming a cavity between the means for conducting a first electrical signal and the means for conducting a second electrical signal;
• means for reflecting light being substantially parallel to the means for conducting a first electrical signal and coupled to the means for conducting a second electrical signal;
• and
• means for inducing tensile stress in the means for conducting a second electrical signal in response to increased temperature.

A method of manufacturing a light modulator comprising:

• providing a substrate;
• forming a first electrode layer over the substrate;
• forming a second electrode layer over the substrate;
• forming a film configured to induce tensile stress in the second electrode layer in response to increased temperature;
• forming a support connecting the substrate to the second electrode layer;
• and
• forming a reflective surface substantially parallel to the first electrode layer and coupled to the second electrode layer, the reflective surface movable along a direction substantially perpendicular to the reflective surface.

A method for balancing thermal coefficients to maintain tension in an interferometric modulator having a substrate and a movable layer separated by a cavity, the interferometric modulator further having a reflective surface on the movable layer facing the cavity, the cavity being configured to cause interference between at least two wavelengths of electromagnetic radiation, the method comprising:

• selecting a material having a first coefficient of thermal expansion for a substrate;
• selecting a material having a second coefficient of thermal expansion for a movable layer;
• and
• selecting a film based at least in part on a comparison of the first coefficient of thermal expansion and the second coefficient of thermal expansion so as to maintain tension in the movable layer.

A method for balancing thermal coefficients to maintain tension in a MEMS device having a substrate and a movable layer separated by a cavity, and a plurality of support structures, the method comprising:

• selecting a material having a first coefficient of thermal expansion for a substrate;
• selecting a material having a second coefficient of thermal expansion for a movable layer;
• and
• selecting a material having a third coefficient of thermal expansion for a thermal expansion coefficient compensation based at least in part on the first coefficient of thermal expansion so as to maintain tension in the movable layer when the MEMS device is exposed to an increased temperature, wherein the material with the third coefficient of thermal expansion extends continuously beneath the plurality of support structures.