Method of forming a spatial light modulator
Described herein is a method ( 400 ) of forming a spatial light modulator device ( 100 ). The method ( 400 ) comprises, at step ( 401 ), providing a planar silicon substrate. At step ( 403 ), a patternable material ( 508 ) is deposited onto a bonding surface ( 506 ) of the silicon substrate ( 502 ). At step ( 404 ), the patternable material ( 508 ) is formed into a predefined patterned structure on the bonding surface ( 506 ). At step ( 405 ), an upper layer substrate ( 504 ) is applied to the predefined patterned structure. At step ( 406 ), a bonding process is performed such that the predefined patterned structure forms a hermetic seal between the silicon substrate ( 503 ) and the upper layer substrate ( 504 ), defining a cavity between the silicon substrate ( 503 ) and the upper layer substrate ( 504 ) to contain a light modulating material ( 104 ).
1 . A method of forming a spatial light modulator device, the method comprising:
providing a planar silicon substrate;
depositing a patternable material onto a bonding surface of the silicon substrate;
forming the patternable material into a predefined patterned structure on the bonding surface;
applying an upper layer substrate to the predefined patterned structure; and
performing a bonding process such that the predefined patterned structure forms a hermetic seal between the silicon substrate and the upper layer substrate, defining a cavity between the silicon substrate and the upper layer substrate to contain a light modulating material,
wherein step of performing a bonding process comprises at least one of: irradiating the predefined patterned structure with ultraviolet radiation to form an adhesive bond between the silicon substrate and upper layer substrate; irradiating the predefined patterned structure with laser light at an interface between the upper layer substrate and the predefined patterned structure; irradiating the predefined patterned structure with infrared radiation to perform a soldering process.
2 . The method according to claim 1 wherein the steps of depositing the patternable material and forming the predefined patterned structure comprise screen printing the patternable material onto the bonding surface at predefined locations to form the predefined patterned structure.
3 . The method according to claim 1 wherein the step of performing a bonding process comprises irradiating the predefined patterned structure with ultraviolet radiation to form an adhesive bond between the silicon substrate and upper layer substrate.
4 . The method according to claim 1 wherein the step of performing a bonding process comprises irradiating the predefined patterned structure with laser light at an interface between the upper layer substrate and the predefined patterned structure.
5 . The method according to claim 1 wherein the step of performing a bonding process comprises irradiating the predefined patterned structure with infrared radiation to perform a soldering process.
6 . A method of forming a spatial light modulator device, the method comprising:
providing a planar silicon substrate;
depositing a patternable material onto a bonding surface of the silicon substrate;
forming the patternable material into a predefined patterned structure on the bonding surface;
applying an upper layer substrate to the predefined patterned structure; and
performing a bonding process such that the predefined patterned structure forms a hermetic seal between the silicon substrate and the upper layer substrate, defining a cavity between the silicon substrate and the upper layer substrate to contain a light modulating material,
wherein the patternable material comprises a photosensitive patternable material.
7 . The method according to claim 6 , further comprising exposing the photosensitive patternable material to light to convert the photosensitive patternable material to a permanent patternable material.
8 . The method according to claim 7 wherein the photosensitive patternable material has a shrinkage of less than 5 percent by volume (vol. %) when formed into the permanent patternable material.
9 . The method according to claim 8 wherein the material has water vapor transmission rate (WVTR) less than 5 gram per square meter per day at 60 degrees Celsius and 90 percent room humidity with a thickness of 500 microns.
10 . The method according to claim 8 wherein the material has boiling water absorption less than 3 percent by weight when submerged in boiling water for 2 hours.
11 . The method according to claim 8 wherein the material has room temperature water absorption less than 1 percent by weight when submerged in 25 degrees Celsius water for 24 hours.
12 . The method according to claim 6 wherein the photosensitive patternable material comprises a photoresist material.
13 . The method according to claim 6 wherein the step of depositing the photosensitive patternable material comprises spin coating a layer of the photosensitive patternable material onto the bonding surface.
14 . The method according to claim 6 wherein the step of depositing the photosensitive patternable material comprises spray coating a layer of the photosensitive patternable material onto the bonding surface.
15 . The method according to claim 6 wherein the step of depositing the photosensitive patternable material comprises rolling a layer of the photosensitive patternable material onto the bonding surface.
16 . The method according to claim 6 further comprising the steps of:
depositing a metallic thin film onto the predefined patterned structure and exposed silicon substrate; and
performing a lift-off process to remove the predefined patterned structure and metallic thin film attached to the predefined patterned structure, leaving the metallic thin film attached directly to the exposed silicon substrate.
17 . The method according to claim 16 wherein the predefined patterned structure is in the form of a negative or inverse of a shape of the hermetic seal.
18 . The method according to claim 6 wherein the step of performing a bonding process comprises exposing the predefined patterned structure to a heat source under pressure to perform a fusion bond process between the silicon substrate and upper layer substrate.
19 . The method according to claim 6 further comprising the step of cleaning the bonding surface of the silicon substrate prior to depositing the patternable material.
20 . The method according to claim 6 further comprising the step of depositing light modulating material onto the silicon substrate within the predefined patterned structure prior to applying the upper layer substrate.
21 . The method according to claim 6 wherein the predefined patterned structure includes an opening such that a light modulating material can be added after the upper layer substrate has been applied.
22 . The method according to claim 6 wherein the patternable material comprises two or more constituent materials.
23 . The method according to claim 22 wherein at least one of the two or more constituent materials comprises properties to define a gasket height.
24 . The method according to claim 22 wherein at least one of the two or more constituent materials comprises properties to define the hermetic seal between the silicon substrate and the upper layer substrate.
25 . The method according to claim 22 wherein at least one of the two or more constituent materials is adhesive so as to adhere the patternable material to the bonding surface.
26 . The method according to claim 25 wherein the patternable material has a shear bonding strength to glass and silicon to be greater than 10 Newton per square millimeter or 10 Megapascals.
27 . The method according to claim 6 wherein the spatial light modulator device is a Liquid Crystal on Silicon (LCOS) device.
28 . The method according to claim 6 wherein the patternable material is a homogeneous material.
29 . The method according to claim 6 wherein the patternable material is absent of spacer elements.
30 . The method according to claim 6 wherein the predefined patterned structure is rectangular.
31 . The method according to claim 6 wherein the predefined patterned structure is non-rectangular.
32 . A liquid crystal microdisplay device formed by the method according to claim 6 .
33 . A method of forming a spatial light modulator device, the method comprising:
providing a planar silicon substrate;
depositing a patternable material onto a bonding surface of the silicon substrate;
forming the patternable material into a predefined patterned structure on the bonding surface;
applying an upper layer substrate to the predefined patterned structure; and
performing a bonding process such that the predefined patterned structure forms a hermetic seal between the silicon substrate and the upper layer substrate, defining a cavity between the silicon substrate and the upper layer substrate to contain a light modulating material,
wherein the steps of depositing the patternable material and forming the predefined patterned structure comprise ink jetting the patternable material onto the bonding surface at predefined locations to form the predefined patterned structure.
34 . The method according to claim 33 wherein the patternable material is an adhesive material.
35 . The method according to claim 33 wherein the patternable material is a non-adhesive material.
36 . The method according to claim 35 wherein the patternable material is an adhesive material.
37 . A method of forming a spatial light modulator device, the method comprising:
providing a planar silicon substrate;
depositing a patternable material onto a bonding surface of the silicon substrate;
forming the patternable material into a predefined patterned structure on the bonding surface;
applying an upper layer substrate to the predefined patterned structure; and
performing a bonding process such that the predefined patterned structure forms a hermetic seal between the silicon substrate and the upper layer substrate, defining a cavity between the silicon substrate and the upper layer substrate to contain a light modulating material,
wherein the steps of depositing the patternable material and forming the predefined patterned structure include 3D printing the patternable material onto the bonding surface at predefined locations to form the predefined patterned structure.
38 . The method according to claim 37 wherein the patternable material is a non-adhesive material.