Method for producing two-dimensional wedge and local encapsulation layer for diffraction optical element

Abstract

To provide a method for forming a three-dimensional feature inwardly on the surface of a material.SOLUTION: Provided is a method including provision of a droplet dispenser that includes an outlet configured so as to dispense an individual droplet of a liquid material, and has a reactant capable of removing a part of a material layer on which a droplet abuts by reacting with the part, provision of a support that is configured so as to support a material on it, where the support and the droplet dispenser can travel relative to each other, and the outlet of the droplet dispenser can be positioned on various individual areas on the surface of a material, and formation of a three-dimensional recess inwardly on the surface of a material by positioning the surface of the material below the droplet dispenser, dispensing droplets to an individual part on the surface of the material in a desired area of the material, and removing at least one portion of the material in the desired area.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure generally relates to selectively wet etching multi-dimensional features inwardly into a material surface, and more specifically to dispensing individual droplets of a material removal chemical onto individual portions of a material surface to form multi-dimensional concave features within controlled individual regions of the material surface.

Background Art

[0002] Three-dimensional features extending inwardly into the surface of a material layer are useful in several applications, for example, forming two-dimensional (2D) wedges on the surface of an optical device and useful in fabricating diffractive optical elements including, among other applications, waveguide combiners and flat optical elements. In some cases, the features are fabricated within an optical device such that an in-coupler, an out-coupler, or both can direct light into or out of the optical layer of the optical device. There is a need to more accurately position the features, including reproducible profile contours, for each device without the need to process a substrate to form an etching mask thereon using a wet removal chemical such as a wet etchant.

Summary of the Invention

[0003] In one aspect, a method of forming three-dimensional features inwardly on a surface of a material includes providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material, the liquid material having a reactant that can remove a portion of a material layer with which the droplets come into contact by reacting with the portion; providing a support configured to support the material thereon, the support and the droplet dispenser being movable relative to each other and the outlet of the droplet dispenser being positionable over various individual regions of the surface of the material; positioning the surface of the material under the droplet dispenser and dispensing droplets onto individual portions of the surface of the material within a desired region of the material to remove at least a portion of the material within the desired region and form a three-dimensional recess inwardly on the surface of the material.

[0004] In another aspect, a method of forming a patterned photoresist on a material layer includes providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material; providing a support configured to support the material layer thereon, the support and the droplet dispenser being movable relative to each other and the outlet of the droplet dispenser being positionable over various individual regions of the surface of the material; providing a first liquid including a photoresist polymer that is dispensable in the form of droplets from the dispenser; providing a second liquid including a photosensitizer, the photosensitizer changing the reactivity of the polymer to electromagnetic energy when mixed with the polymer; positioning the surface of the material under the droplet dispenser and dispensing droplets of the first liquid onto the entire surface of the material layer; and dispensing droplets of the second liquid only onto desired individual regions of the material layer to mix the first liquid and the second liquid within the desired individual regions of the material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0005]

Figure 1A

Figure 1B

Figure 1C

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Figure 3C

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Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

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DETAILED DESCRIPTION OF THE INVENTION

[0006] Referring initially to FIGS. 1A, 1B, and 1C, a schematic side cross-sectional view and an isometric view of an optical device 10 are shown in which a 2D wedge 11 is formed in an encapsulation layer of the optical device 10 (FIGS. 1B, 1C), and this optical device 10 is useful as a waveguide for virtual reality imaging and other applications. The encapsulation layer 12 extends over and covers the optical layer 19, and the optical layer 19 is provided to receive light through its own incoupler 15, and the light is transmitted through the optical layer 19 and is capable of being transmitted out of the optical device through its own outcoupler 16, and all of these are integrally formed on the substrate 14. The optical device 10 includes a 2D wedge 11 in the region of the encapsulation layer 12 above the outcoupler 16, and the 2D wedge 11 is here formed using an inkjet wet etching apparatus 1100 (FIG. 11), and the inkjet wet etching apparatus 1100 dispenses an etchant to selectively and locally remove material from the encapsulation layer 12 of FIG. 1A and locally forms a 2D wedge that extends inwardly from the outer surface of the encapsulation layer 12 above the outcoupler 16 as shown in FIG. 1B. The 2D wedge 11 is formed in the encapsulation layer 12 by etching a wedge profile 11a and leaving the wedge 11 in place as a variable thickness region of the encapsulation layer 12 in the region directly above the outcoupler 16, whereby a relatively thick encapsulation layer 12 covers the optical layer 19 and creates conditions approximating total internal reflection at the interface between the optical layer 19 and the dielectric layer 12 in the region of the optical layer 19 between the incoupler 15 and the outcoupler 16, and by forming a shallower conical feature of the 2D wedge 11 within or as a part of a portion of the encapsulation layer 12 above the outcoupler 16, the transmission characteristics and refractive characteristics of the device are changed.

[0007] To form the 2D wedge 11, as shown in FIG. 1A, an optical device 10 having an encapsulation layer 12 of uniform thickness on an optical layer 19 supported on its substrate 14 is attached to the movable stage 1114 of the inkjet etching apparatus 1100 of FIG. 11. As shown in FIG. 11, the inkjet etching apparatus 1100 includes a table 1102 supported on its base 1112 and movable in the X direction with respect to the base 1112, and at least one inkjet type dispenser 1104, here four such dispensers 1104a - 1104d, each of the dispensers 1104a - 1104d being configured to dispense droplets 1106 of a liquid material and having outlet nozzles 1108a - d that terminate at droplet dispensing openings 1110a - 1104d facing the table 1102. The stage 1114 is rotatably coupled to the table 1102 via a shaft (not shown) connected to a stepper or servo motor (not shown) within the table 1102, for example, whereby the stage 1114 is rotatable about its center 1116 in the θ direction of FIG. 11. To perform wet etching or removal of individual portions of the encapsulation layer 12 to form the 2D wedge 11 within a desired region of the outer surface of the encapsulation layer 12, here on the outcoupler 16 of the device 10, the stage 1114 is positioned under the droplet dispensing opening 1110 of the outlet nozzle 1108 of the inkjet dispenser 1104 of the inkjet etching apparatus 1100, where the encapsulation layer 12 faces the outlet nozzle 1108 of the inkjet etching apparatus, and the stage 1114 is rotated and moved in the X direction to position individual portions or locations on the encapsulation layer 12 where the 2D wedge 11 is to be formed under the droplet dispensing openings 1104a - 1104d of one or more inkjet dispensers 1104a - 1104d. The surface of the stage 1114 facing the nozzles is located at a distance greater than the thickness of the optical device 10 from the droplet dispensing opening 1010 of the outlet nozzle 1008, and the distance between the droplet dispensing opening 1110 and the surface of the encapsulation layer 12 of the optical device 10 is, for example, on the order of 2 mm to 5 mm.

[0008] Here, an optical device 10 including an optical layer 19 and having an incoupler 15 and an outcoupler 16 encapsulated by an encapsulation layer 12 is disposed on a stage 1114. Here, by dispensing droplets 1106 of a wet etching chemical or a reactive chemical onto the encapsulation layer 12 from one or more droplet dispensing openings 1110 of an inkjet device 1104, a concave, substantially conical recess or wedge contour 11a that forms the conical outer surface of a 2D wedge 11 is etched, thereby forming a 2D wedge 11 feature. The wedge contour 11a forming the outer surface of the 2D wedge 11 is provided by performing a larger etching where the deepest point of the wedge contour 11a is to be formed, and gradually reducing the etching performed on the side surface of the 2D wedge 11 or where the wedge contour 11a has the shape of a conical surface, and gradually reducing the etching radially outward from the deepest point of the wedge contour 11a to the edge of the wedge contour 11a along the side surface portion. Examples of possible layer materials of the encapsulation layer 12 in which the 2D wedge contour 11a is formed and the etchants appropriately paired with them include the following pairs, namely, SiO2 material and DHF etchant, Si3N4 material and HF or H3PO4 etchant, TiO2 material and SC1 etchant, carbon-based material and organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using a KOH etchant. The etching of the 2D wedge contour 11a for forming the 2D wedge 11 in a film layer such as the encapsulation layer 12 can be performed in various different ways.

[0009] In one approach or aspect for forming the 2D wedge 11, droplets 1106 of an etchant, each having the same or substantially the same etchant concentration or molar concentration, are uniformly dropped as droplets 1106 from an injection nozzle 1108 over the region where the 2D wedge 11 is to be formed. As the etchant reacts with the underlying thin film material and here the encapsulation layer 12 onto which the etchant is dropped, the etchant is consumed in the reaction with the thin film material. The reaction rate and consumption rate of the etchant are related to time, and the etching reaction can be varied or stopped by the addition of a quenching chemical. In one aspect, as shown in FIG. 13, an inkjet dispenser 1104a that supplies the etchant to its outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. Here, the first line 1118a contains an etchant of uniform concentration or molar concentration, and a quenching chemical of uniform concentration is provided in the second line 1120a. Each of the first line 1118a and the second line 1120a includes valves 1122a, 1124a, and the valves 1122a, 1124a open selectively, and the flow passing through the valves 1122a, 1124a, i.e., the flow of the etchant flowing into and through the droplet dispensing opening 1110a of the outlet nozzle 1108a (first line 1118a, valve 1122a) and the flow of the quenching chemical (line 1120a, valve 1124a) can be adjusted or changed. The quenching chemical reacts with the etchant preferentially over the etchant reacting with the encapsulation material 12, so that the etchant is consumed by the quenching chemical and the etching of the encapsulation layer 12 stops.

[0010] To fabricate the 2D wedge 11, i.e., to etch the conical wedge profile 11a of FIGS. 1B and 1C using the present inkjet printer 1100, an etchant is discharged through the first line 1118a to the exit nozzle 1108a to cover the entire area where the wedge profile 11a is to be formed. Immediately thereafter, a quenching chemical is discharged to the periphery of the area where the wedge profile 11a is being formed. The area where the wedge profile 11a to be formed, which is located inside the outer periphery of the formed wedge 11, gradually becomes deeper and will receive the quenching chemical at individual time intervals between the dispensing of the quenching chemical at gradually slower times, whereby the deepest point of the wedge 11 being formed receives the quenching chemical last. The position of the encapsulation layer 12 inside the outer periphery of the wedge profile 11a being formed receives the quenching chemical by the movement of the stage 1114 for positioning individual regions of the encapsulation layer 12 under the flow 1106 of the droplets 1106 of the quenching chemical at a predetermined time when the wedge 11 has the desired remaining thickness of the encapsulation layer 12 at that position. After the entire surface of the wedge profile 11a of the encapsulation layer 12 is quenched, i.e., after the conical wedge profile 11a is formed inwardly on the surface of the encapsulation layer 12, the encapsulation layer 12 is washed with deionized water dispensed by the rinse nozzle 1126 of FIG. 11, and the etched debris, any residual etchant, the quenching chemical, and any by-products formed therein are removed. Thereafter, the optical device 10 with the wedge formed is removed from the stage 1114 and placed in a cleaning and drying station 1128 having a spin rinse chuck 1130. Alternatively, instead of providing two supply lines 1118a, 1120a, an inkjet dispenser 1104a may be used to dispense the etchant, and an inkjet dispenser 1104b is used to dispense the quenching material.Furthermore, to reduce the processing time for etching the wedge contour 11a, two or more of the inkjet dispensers 1104a to 1104c may be used to dispense one or both of the etchant and the quenching chemical substance, or at least two of the inkjet dispensers 1104a to 1104d may be used to dispense the etchant, and one or more different inkjet dispensers among the inkjet dispensers 1104a to 1104d may be used to dispense the quenching chemical substance.

[0011] In a second aspect, the etchant is dispensed with a change in time or amount across the wedging region. As the dispensed etchant reacts with the underlying material, the etchant is consumed. To achieve a deeper etch of the encapsulation layer 12, more droplets 1106 (an increase in droplet density) are released into the deeper etch region and fewer droplets 1106 (a lower droplet density) are released into the shallower region of the wedging region to be formed, relatively simultaneously or while the etchant is depleted or consumed within the region where the deeper portion of the wedge profile 11a is to be formed as compared to the region to be formed shallower. In this aspect, the droplets dispensed by the inkjet dispenser 1104 have a uniform etchant concentration. The etchant reacts at the position where it contacts the encapsulation layer 12 until its chemical reaction with the material of the encapsulation layer 12 is exhausted, i.e., until the etchant is almost completely consumed, and a limited amount of etching occurs for each droplet 1106. Thus, in the region where fewer droplets 1106 are dispensed, the inward etching in the encapsulation layer 12 becomes smaller relatively simultaneously with or over a period during which the etchant is consumed, and in the region where more droplets are released, a larger inward etching is performed in the encapsulation layer 12 relatively simultaneously with or over a period during which the etchant is consumed. Preferably, the etchant is continuously and systematically discharged onto the surface of the encapsulation layer 12 using the X-direction movement and θ (rotation) movement of the stage 1114 for dropping the droplets 1106 at a rate not faster than the consumption rate due to the reaction with the encapsulation layer material 12, where the stage 1114 moves the encapsulation layer 12 under the flow of the droplets 1106 and selectively replenishes the etchant at individual locations on the encapsulation layer 12. The region of the encapsulation layer 12 that receives the etchant droplets 1106 decreases stepwise or continuously around the deepest point of the wedge profile 11a formed inwardly in the encapsulation layer 12 as the etchant is consumed by the reaction with the encapsulation layer, whereby the etchant is not dispensed into the region of the already formed wedge profile 11a that is shallower than a certain depth, i.e., the region that has already reached the final depth of the wedge profile 11a by etching.The stage 1114 first moves the encapsulation layer 12 under the droplet dispensing opening 1110 of the outlet nozzle 1108 to cover the entire area where the wedge contour 11a that defines the outer surface of the wedge 11 is to be formed. Then, the area centered on the deepest location of the wedge contour 11a gradually becomes smaller, and the stage finally stops, positioning the deepest position of the wedge contour 11a formed under the last droplet 1106 among the droplets 1106 discharged from the droplet dispensing opening 1110 of the outlet nozzle 1108, and completing the etching of the encapsulation layer 12 to form the wedge contour 11a, and thus the wedge 11, within the encapsulation layer 12. By this method, the portion of the encapsulation layer 12 where the shallower side surface of the wedge contour 11a is formed receives fewer droplets 1106 of the etchant, is etched by the fewer droplets 1106, and the portion of the deepest area of the wedge contour 11a etched into the interior of the encapsulation layer 12 receives the most droplets 1106, where the encapsulation layer 12 is most deeply indented inward. Thereafter, the surface of the encapsulation layer 12 including the outer surface of the newly formed wedge 11 is cleaned with deionized water dispensed by the cleaning nozzle 1126, removing the etched debris, the etchant, the quenching chemicals, and any by-products formed there. Thereafter, the optical device 10 is removed from the support 1114 and placed within the cleaning and drying station 1128. Similar to the first aspect of forming the wedge contour 11a, a plurality of the inkjet dispensers among the inkjet dispensers 1104a - b can be used to eject droplets, thereby potentially shortening the time required to etch the wedge contour 11a.

[0012] In a third aspect, an etchant for forming the wedge contour 11a is discharged with a concentration or molar concentration change across the region where the wedge contour 11a defining the wedge 11 of the encapsulation layer 12 is to be formed. As the etchant reacts with the underlying material of the encapsulation layer 12, the etchant is consumed. In order to achieve deeper etching within a desired region of the encapsulation layer 12, droplets 1106 with a higher etchant concentration or molar concentration are discharged within the region to be etched deeper, and droplets with a lower concentration (diluted droplets) are discharged within the region to be etched less, i.e., within the shallower region of the wedge contour 11a. To achieve this, in one aspect, a dispenser 1104 that supplies the etchant to the outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. The first line 1118a contains an etchant with a uniform concentration or molar concentration, and a diluent, such as deionized water, is supplied in the second line 1120a. Each of the first line 1118a and the second line 1120a includes valves 1122a, 1124a, and the valves 1122a, 1124a open selectively to regulate or change the flow passing through the valves 1122a, 1124a, i.e., the flow of the etchant flowing into and through the outlet nozzle 1108a (line 1118a, valve 1122a) and the flow of the diluent (line 1120a, valve 1124a). By the relative flow of the diluent and the etchant, etchants of various concentrations are obtained for each droplet 1106 dispensed from the droplet dispensing aperture 1110a. The dispensed etchant 1116 reacts at the position in contact with the encapsulation layer 12 until the chemical reaction is exhausted, and limited etching is performed for each droplet. When droplets 1106 with a lower etchant concentration are dispensed, less etching is performed. The etchant droplets 1106 are continuously discharged at a rate not faster than their consumption rate due to their own reaction with the encapsulation layer material 12, where the stage 1114 moves to pass under the inkjet stream 1106 through the wedge contour 11a forming the region of the optical device 10.The portion of the region where the wedge contour 11a is to be formed, and where the etchant is dispensed, extends over the entire region where the wedge contour 11a is to be formed. Here, the droplet dispensing opening 1110a of the outlet nozzle 1108a discharges droplets 1106 in which the ratio of the etchant to the diluent increases more significantly, from a position around the region of the encapsulation layer 12 to be etched, to a position on the encapsulation layer 12 where the deepest etching for forming the wedge contour 11a is performed. At this location, the diluent is not discharged together with the etchant. Thus, the shallower side surfaces of the wedge contour 11a receive less concentrated etchant droplets, and the deepest region of the encapsulation layer 12 where the wedge contour 11a is formed receives the most concentrated etchant droplets 1106, where the wedge contour 11a is etched to the deepest extent. Thereafter, the surface of the encapsulation layer 12 and the formed wedge 11 are cleaned with deionized water dispensed by the rinse nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Thereafter, the optical device 10 is removed from the support 1114 and placed within the cleaning and drying station 1128. Similar to the first and second aspects, a plurality of the inkjet dispensers among the inkjet dispensers 1104a - b are used to eject droplets of various concentrations, thereby potentially shortening the time required to etch the wedge contour 11a. Additionally, the etchant containing etchants of various concentrations can be supplied to one or more of the inkjet dispensers 1104a - d. Here, the less concentrated droplets 1106 are dispensed to the region of the surface of the encapsulation layer 12 where the variable-depth opening should be shallower, and the more concentrated etchant is dispensed to the region of the surface of the encapsulation layer 12 where the variable-depth opening should be deeper. In this approach, one of the inkjet dispensers 104a - d can dispense the diluent, which is then mixed with etchants of various concentrations in various regions of the encapsulation layer, resulting in a continuous or nearly continuous change in the etchant concentration in the liquid over the encapsulation layer from the deepest part to the shallowest part of the wedge contour 11a being formed.

[0013] In a fourth aspect, the etchant is discharged in droplets 1106 of various sizes across the region of the encapsulation layer where a wedge profile 11a for forming the wedge 11 is to be formed. As the etchant reacts with the underlying material of the encapsulation layer 12, the etchant is consumed. To achieve a deeper etching into the encapsulation layer, larger droplets 1106 are discharged within the deep etching region and smaller droplets 1106 are discharged within the region of the shallower wedge profile 11a. To achieve this, the inkjet printer 1100 includes an inkjet dispenser 1104 that can dispense smaller or larger droplets that are dropped as droplets 1106 through the droplet dispensing aperture 1110 of the outlet nozzle 1108. The etchant reacts at the position where it contacts the encapsulation layer 12 until the chemical reaction is exhausted, and limited etching is performed for each droplet, with smaller etching being performed where smaller etchant droplets 1106 are dispensed. Here, the viscosity of the droplets is increased to prevent large movement of the droplets from their placement position on the encapsulation layer 12. The etchant droplets 1106 are sequentially discharged across the entire region of the encapsulation layer 12 where the wedge profile 11a for forming the wedge 11 is to be formed, at a rate not faster than the rate of consumption of the etchant by its reaction with the encapsulation layer material 12. Here, the stage 1114 moves various portions of the wedge profile 11a formed to various depths of the encapsulation layer 12, and thus the optical device 10, under the flow of the droplets 1106. The size of the droplets 1106 gradually increases from the outer periphery of the wedge profile 11a to be formed to the most deeply etched position. Thus, the shallower side regions of the wedge profile 11a being formed receive smaller etchant droplets 1106, and the deepest region of the wedge profile 11a being formed receives the largest droplets, and thus at that position, the encapsulation layer 12 is etched deepest. Thereafter, the surface of the encapsulation layer 12 on which the wedge 11 has been formed is cleaned with deionized water dispensed by the cleaning nozzle 1126, removing etched debris, etchant, quenching chemicals, and any by-products formed there.Subsequently, the optical device 10 is removed from the support 1114 and placed within a cleaning and drying station 1128.

[0014] Similar to the first to third aspects for forming the wedge 11, a plurality of jet dispensers among the inkjet dispensers 1104a to 1104b can be used to eject droplets of various sizes, or each of the inkjet dispensers 1104a to 1104d of the inkjet dispensers 1104a to 1104d is configured to provide droplets within various partial ranges of sizes, thereby shortening the time required to etch the wedge profile 11a.

[0015] FIG. 2 is a flowchart showing a series of operations for fabricating a 2D wedge 11 within the encapsulation layer 12 of the optical device 10 according to a series of processes described with respect to FIG. 1. First, the optical layer 19 is prepared. However, the encapsulation layer 12 needs to have its thickness varied to achieve the desired effect for the optical device 10, and thus, the 2D wedge 11 can be formed. Here, a processing sequence for forming a 2D wedge in the encapsulation layer 12 will be described.

[0016] In operation 201, the optical device 10 is mounted on the stage 1114, and in operation 203, the stage 1114 within the inkjet wet etching apparatus 1100 positions the desired location on the encapsulation layer 12 where the 2D wedge is to be formed under the droplet dispensing opening 1110 of the outlet nozzle 1108 of the inkjet dispenser 1104 by movement in the X direction and the θ direction of FIG. 11. In operation 205, an etchant capable of reacting with (etching) the material of the encapsulation layer 12 is released as droplets 1106 from the droplet dispensing opening. Preferably, for the above etchant, the etching rate of the material of the optical layer 19 is about 100 times or more lower than the etching rate of the encapsulation layer 12 when exposed to the same etchant.

[0017] In one aspect, after the etchant is discharged through line 1118a to outlet nozzle 1108a so as to cover the entire area where the wedge profile 11a for forming wedge 11 is to be formed, the quenching chemical is discharged immediately thereafter to the periphery of the area, where, in operation 211, the wedge profile 11a is formed. The position of the encapsulation layer 12 inside the outer periphery of the wedge profile 11a being formed receives the quenching chemical by the movement of stage 1114 to place individual areas of the encapsulation layer 12 under the flow of droplets 1106 of the quenching chemical at a predetermined time when sufficient material for the wedge profile 11a to form the desired thickness of the encapsulation layer 12 at that position has been removed. Thereafter, the wedge profile 11a being formed gradually becomes deeper. When the entire surface of the wedge profile 11a of the encapsulation layer 12 is quenched, in operation 221, the surface is washed with deionized water dispensed by rinse nozzle 1126, removing etched debris, any residual etchant, the quenching chemical, and any by-products formed therein. Next, in operation 231, the optical device 10 on which the wedge 11 is formed is removed from stage 1114 and, in operation 241, placed within a cleaning and drying station 1128 having a spin rinse chuck 1130, and the surface of the encapsulation layer 12 on which the 2D wedge is formed is further rinsed and dried.

[0018] In the second aspect, in operation 205, by dispensing more droplets (increasing the droplet density) within the region where the wedge contour 11a is formed deeper into the encapsulation layer 12, etching with a greater depth is achieved, and within the shallower region of the wedge contour 11a to be formed, fewer droplets (lower droplet density) are released. Here, the inkjet dispenser 1104 drops droplets 1106 with a uniform etchant concentration so as to contact the region of the encapsulation layer 12 where the wedge contour 11a is to be formed until the chemical reaction is exhausted, that is, until the etchant is almost consumed, and limited etching is performed for each droplet. Thereafter, in operation 213, due to the movement of the stage 1114 and thus the movement of the encapsulation layer 12 under the flow of the droplets 1106, at a separate location on the encapsulation layer 12 where the wedge contour 11a is formed over time in operation 213, the etchant is selectively replenished, thereby realizing a change in the density of the droplets on the surface of the region where the wedge contour 11a is formed. Alternatively, when the viscosity of the droplets 1106 is relatively high and does not move significantly from the position where they are dropped on the encapsulation layer, by passing the wedge contour 11a forming the region of the encapsulation layer 12 once under the droplet dispensing outlet 1010, more droplets 1106 can be dropped at a position where the wedge contour 11a is deeper than the shallower formed region, thereby causing a thicker layer of the etchant to exist above the deeper position of the wedge contour 11a to be formed compared to the shallower formed region. Thereafter, in operation 223, the surface of the encapsulation layer 12 including the wedge 11 is cleaned with deionized water dispensed by the cleaning nozzle 1126, and the etched debris, etchant, quenching chemicals, and any by-products formed therein are removed. From here, in operation 233, the optical device 10 is removed from the support 1114, and in operation 243, it is placed within the cleaning and drying station 1128. Thereafter, the surface of the encapsulation layer 12 with the 2D wedge formed is further rinsed and dried.

[0019] In a third aspect, in operation 205, the etchant is discharged in droplets 1106 of various etchant concentrations at various positions of the wedge profile 11a being formed. In operation 215, droplets with a higher etchant concentration or molar concentration are discharged into the region of the encapsulation layer 12 to be etched deeper, and low-concentration droplets (diluted droplets) are discharged within the region to be etched less severely, i.e., at a shallower position of the wedge profile 11a to be formed. Thereafter, in operation 225, the surface of the encapsulation layer 12 including the wedge 11 is cleaned with deionized water dispensed by the rinse nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. From here, in operation 235, the optical device 10 is removed from the support 1114 and, in operation 245, placed within the cleaning and drying station 1128, after which the surface of the encapsulation layer 12 on which the 2D wedge has been formed is further rinsed and dried.

[0020] In a fourth aspect, as the etchant discharged in operation 205, droplets of various sizes are discharged across the region of the encapsulation layer 12 where the wedge profile 11a is to be formed. In operation 217, larger droplets are discharged within the deeper etching region and smaller droplets are discharged within the shallower etching region, where the size of the droplets is adjusted by the inkjet dispenser 1104. The shallower sides of the wedge profile 11a being formed receive smaller etchant droplets 1106, and the deepest region of the wedge profile 11a being formed receives the largest droplets, and thus at that position, the encapsulation layer 12 is etched deepest. Thereafter, in operation 227, the surface of the encapsulation layer 12 on which the wedge 11 has been formed is cleaned with deionized water dispensed by the cleaning nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. In operation 237, the optical device 10 is removed from the support 1114 and, in operation 247, placed within the cleaning and drying station 1128, after which the surface of the encapsulation layer 12 on which the 2D wedge has been formed is further rinsed and dried.

[0021] Referring now to FIGS. 3A - 3C, an additional method for forming a photoresist layer for forming a wedge profile as in the optical layer of FIG. 5E is shown. Here, an inkjet printer 1100 is used to deposit individual droplets 1106 of photoresist material to form a photoresist layer 30 on a thin film layer 19c present on a substrate 21 below, where the formed photoresist layer 30 includes a composition that varies over its entire length, whereby individual non - uniform portions 23 are formed within the photoresist layer 30, and whereby the photoresist layer 30 has three - dimensional features 31 formed inwardly therein after being exposed to an electromagnetic energy source such as a UV source or other source and developed. Thereafter, by anisotropic etching, such as in a plasma etching chamber, the three - dimensional profile of the three - dimensional recesses in the photoresist 30 is transferred to the underlying thin film layer 19c, forming a structure similar to the 2D wedge of FIG. 5E.

[0022] The photoresist material for forming the photoresist layer 30 is dispensed in a liquid form and then baked to cure, for example, by including a heater (not shown) thermally connected to the stage 1114 under the stage 1114 of the inkjet device 1100. Here, the composition of the photoresist layer 30 is changed in the non-uniform region 23 compared to the remaining portion of the photoresist of the photoresist layer 30 formed on the thin film layer 19c, and is used to form a three-dimensional feature 31 in the photoresist layer 30 after being exposed to electromagnetic radiation and developed. The composition of the photoresist 30 in the portion of the photoresist 30 deposited in the non-uniform region 23 also varies over the entire length or width of the non-uniform region 23. For example, the polymer, solvent, and non-sensitizer additive components of the photoresist material dispensed as droplets 1106 by the inkjet device 1100 can be maintained in a uniform state over the length, width, and depth of the photoresist layer formed on the thin film layer 19c, but the sensitizer portion of the photoresist that changes the properties of the polymer of the photoresist material when exposed to appropriate electromagnetic energy such as UV light is unevenly contained in the photoresist layer 30, that is, it is unevenly contained between the non-uniform region 23 of the photoresist layer 30 and the remaining portion of the photoresist layer 30, and also within the non-uniform region 23 of the photoresist layer 30.

[0023] To form the non-uniform region described above, the first line 1118a of the inkjet dispenser 1104a is configured to supply the polymer, solvent, and non-photosensitizer additive components of the photoresist material, and the second line 1120a of the inkjet dispenser 1104a is configured to supply the photosensitizer to the inkjet dispenser 1104 and thus to the outlet nozzle 1108a. With the substrate 1102 fixed to the stage 1114, the stage 1114 rotates around its axis 1116 and moves in the X direction using the movement of the table 1102, positioning the entire region of the upper surface of the thin film layer 19c to face the outlet droplet dispensing opening 1010 of the dispensing nozzle 1108 for receiving the polymer, solvent, and non-photosensitizer additive components of the photoresist. When the droplet dispensing opening 1110 of the outlet nozzle 1108 faces the portion of the thin film 19c where the non-uniform region 23 is to be formed, the valve 1124a is also opened, and the polymer, solvent, and non-photosensitizer additive components of the photoresist flow simultaneously onto the thin film layer 19c together with the photosensitizer.

[0024] For example, assume that the three-dimensional feature 31 is circular in the plan view, extends from its edge 31a to its deepest part 31b, has a conical contour similar to the wedge contours 11a and 2D wedge 11 shown in FIGS. 1B and 1C, and the depth transition from its edge 31a to the deepest part 31b is smooth. When the surface of the thin film layer 19c directly below the droplet dispensing opening 1110 is an area where the three-dimensional feature 31 should not be formed, only the polymer, solvent, and non-photosensitizer additive components of the photoresist are dispensed as droplets 1106. While the substrate 21 is placed under the droplet dispensing opening 1110 of the exit nozzle 1108, the substrate 19c is moved to the first position, i.e., the position of the end 31a of the three-dimensional feature 31 to be formed directly below the droplet dispensing opening 1110, and the photosensitizer is added to the polymer, solvent, and non-photosensitizer additive components of the photoresist material dispensed as droplets 1106 from the droplet dispensing opening 1110. While the stage 1014 moves the substrate 21 to place the deepest part 31b of the three-dimensional feature 31 to be formed under the droplet dispensing outlet 1110, more photosensitizer is continuously added to the polymer, solvent, and non-photosensitizer additive components of the photoresist material dispensed as droplets 1106 through the droplet dispensing opening 1110a, whereby the photosensitizer in the mixture of the dispensed photoresist polymer, solvent, and non-photosensitizer additive and the photosensitizer reaches the maximum concentration at the deepest position of the three-dimensional recess 1214 to be formed, and this concentration gradually, here almost linearly, decreases as the stage 1114 traverses the position of the thin film layer under the opening 1110 from the deepest part 31b of the three-dimensional feature 31 to the shallowest position (occurring at the end 31a). The resulting photoresist layer 30, which is sensitive to electromagnetic energy only within the region where the photosensitizer is present, can be formed by passing once under the exit nozzle 1108 over the entire surface of the thin film layer 19c, or multiple layers of the photoresist polymer, solvent, and non-photosensitizer additive components can be formed at appropriate positions (where a photosensitizer with a certain gradient can be dispensed to form the photoresist layer 30) for forming the photoresist layer 30.Here, for example, while moving the substrate 21 from the deepest part 31d of the non-uniform region 23 of the photo resist layer 30 being formed toward the shallower peripheral 31a portion thereof, first, the photosensitizer is added only at the deepest part 31d. Therefore, in the continuous pass for forming the non-uniform region 23 of the photo resist layer 30, the region extending from the deepest part 31d to the end part 31a continuously increases, and finally, in the last pass of the dispensed droplets 1106, the photosensitizer is dispensed over the entire region where the non-uniform portion 23 is formed. In addition, the photo resist layer 30 can be formed by flowing only the photo resist polymer, solvent, and non-photosensitizer additive components through the inkjet dispenser 1104a, and the photosensitizer is flowed through the adjacent inkjet dispenser 1104b. As a result, a photo resist layer having a locally electromagnetic energy-sensitive region is formed, and this locally electromagnetic energy-sensitive region has a certain gradient sensitivity to the electromagnetic energy that causes a change in the structure of the photo resist layer.

[0025] The photo resist layer 30 having a photosensitizer region with a variable concentration formed to form the non-uniform region 23 is exposed to electromagnetic radiation to which the combination of the polymer and the photosensitizer is sensitive, and then the material properties of the photosensitizer region with a variable concentration are changed. As a result, more polymers in the deepest region to be formed in the non-uniform region 23 become more easily etched with the changed properties, and the improvement in the etchability drops to relatively zero at the end part 31a of the three-dimensional feature 31 to be formed. Thereafter, the substrate 23 with the exposed photo resist layer is exposed to the developer, the reacted polymer is dissolved and washed away, and a three-dimensional feature 31 is generated in the structure of the photo resist 30 in FIG. 12C.

[0026] Alternatively, when the photosensitizer causes the polymer to be more resistant to dissolution by the developer when exposed to electromagnetic energy, the sequence described above is reversed, and the region of the photoresist being formed, which would not have the three-dimensional feature 31, receives the photosensitizer, and as the end 31a of the three-dimensional feature 31 being formed comes to be under the droplet dispensing opening 1110, the amount of the photosensitizer decreases, such that the closer to the deepest part 31b of the three-dimensional feature 31 being formed, the less photosensitizer there is, and at the position of the deepest part 31 of the three-dimensional feature 31 being formed, the photosensitizer has a minimum concentration of slightly zero.

[0027] Referring to FIG. 4, a processing sequence for forming the three-dimensional feature 31 is shown in process flow format. First, in operation 400, a substrate 23 having a thin film layer 19c, which can be, for example, an encapsulation layer 12 formed on the optical layer 19 as shown in FIG. 1, is attached to the stage 1114 of the inkjet printer 1100. Next, in operation 402, the stage is moved to position the thin film layer 19c under the droplet dispensing opening 1110 of the inkjet dispenser 1104. Next, in operation 404, while the stage is being moved in the X direction and the θ direction, droplets of the photoresist component are ejected from the droplet dispensing opening 1110 onto the thin film layer 19c, whereby a gradient of the photosensitizer exists within the region of the photoresist layer 30 in which the concave feature is being formed. After the entire thickness of the photoresist layer has been deposited and baked, in operation 406, the photoresist is exposed to electromagnetic radiation that can change the material properties of the polymer in the photoresist, with or without the presence of the photosensitizer, and in operation 408, the exposed photoresist layer 30 is developed. Next, in operation 410, the developed photoresist layer 30 is rinsed with a solvent that dissolves the polymer and the photoresist having (or not having) the photosensitizer, and a three-dimensional feature 31 is formed inwardly in the layer of the photoresist 30.

[0028] In FIGS. 5A - 5C, a schematic side view of the result of a series of processing operations used to fabricate an optical device 10 including a recess 50a extending inwardly into an optical layer 19 of the optical device 10, useful as a waveguide for virtual reality imaging and other applications, is shown. Contrary to the method of forming the feature 31 of FIGS. 3 and 4, where a photoresist layer 30 integrally including regions having variable photoresist material properties is formed, here, the entire thickness of the photoresist layer 30 is formed to cover the optical layer 19 and has continuous material properties across the entire surface of the photoresist layer 30. This optical device 10 with the photoresist layer 30 is then exposed to anisotropic etching conditions. In one strategy, as can be seen in FIGS. 5A - 5C, a recess or depression 50a in the photoresist layer is transferred to the underlying optical layer 19. In another strategy, as can be seen in FIGS. 5D and 5E, without providing a photoresist layer, a recess or depression 50b is directly formed in the optical layer 19 by local inkjet etching. It is possible to create conditions that enable the photoresist wedge 50 illustrated in FIG. 5B, fabricated by using a relatively thick photoresist layer 30 to cover the optical layer 19 of FIG. 5A and form an inwardly directed recess 50a in the photoresist 30 of FIG. 5A. Thereby, the photoresist layer 30 of FIG. 5B is used as a mask for etching the optical layer 19 and for transferring the wedge 50 of FIG. 5B as the optical layer wedge 50c of FIG. 5C to the optical layer 19.

[0029] To form a 2D photoresist wedge 50 as a part of the photoresist layer 30, an optical device 10 having a photoresist layer 30 of uniform thickness is attached to the movable stage 1114 of the inkjet printer 1100 of FIG. 11 as shown in FIG. 5A. Here, the printer 1100 functions as a local dispenser of an etchant or reactant with respect to the surface of the photoresist layer 30 of the device 10 and can remove or etch away individual portions of the material of the photoresist layer 30. The printer 1102 is supported on its base 1112 and includes a table 1102 movable in the X direction with respect to the base 1112 and at least one inkjet type dispenser 1104, here four such dispensers 1104a - 1104d, each of the dispensers 1104a - 1104d being configured to dispense droplets 1106 of a liquid material and having an outlet nozzle 1108 selectively facing the table 1102. The stage 1114 is rotatably coupled to the table 1102 via a shaft (not shown) connected to a stepper motor (not shown) within the table 1112, for example, and the stage 1114 is rotatable about its center 1116 in the θ direction of FIG. 11. To etch the photoresist layer 31 to form a 2D photoresist wedge 50 having a topography similar to that of the conical 2D wedge 11 of FIGS. 1B and 1C within a desired region of the photoresist layer 31, the stage 1114 is positioned under the outlet 1108 of the inkjet dispenser 1104 of the inkjet etching device 1100, where the side of the photoresist layer 30 of the device 10 faces the droplet dispensing outlet 1110 of the outlet nozzle 1108, and the stage 1114 rotates and moves in the X direction to position individual portions of the position on the device 10 where the 2D photoresist wedge 11 is to be formed under the droplet dispensing outlets 1110 of the outlets 1108 of one or more of the inkjet dispensers 1104a - 1104d.The surface of the stage 1114 facing the nozzle is located at a distance greater than the thickness of the optical device 10 from the droplet dispensing opening 1010 at the outlet of the outlet nozzle 1008 of the inkjet nozzle, and the distance between the outlet of the nozzle and the surface of the photoresist layer 30 of the optical device 10 is about 2 mm to 5 mm.

[0030] Here, the optical device 10 covered with the photoresist layer 30 is disposed on the stage 1114, and by etching an inward recess 50a in the outer surface of the photoresist layer 30, wet etching or droplets 1106 of a reactive chemical are dispensed onto the photoresist layer 30 from one or more outlets 1108 of the inkjet dispenser 1104, whereby a 2D photoresist wedge 50 is formed in the existing photoresist layer 30 of FIG. 5A, and the resulting recess 50a is shown in FIG. 5B. The contour of the recess causes a greater etching where the deepest point of the recess 50a is to be formed, and on the side surface extending from the deepest point of the recess 50a to be formed, or in an annular region, i.e., where the side surface portion extends radially outward from the deepest part of the recess 50a to be formed, by causing a gradually smaller etching. Examples of the material of the photoresist layer 30 and its appropriately paired etchant include a carbon-based material and an organic solvent or a photoresist removal etchant. The etching of the recess 50a in the photoresist layer 30 can be performed in various different ways.

[0031] In one approach or aspect for forming the recess 50a, an etchant having the same etchant concentration or molar concentration is uniformly dropped as droplets 1106 from the injection nozzle 1108 over the area where the recess 50a for forming the photoresist wedge 50 is to be formed. As the etchant reacts with the thin film material beneath where it is dropped, the etchant is consumed in the reaction with the photoresist 30. The reaction rate and consumption rate of the etchant are functions of time, and the total amount of photoresist locally etched away can be changed by the addition of a quenching chemical. In one aspect, as shown in FIG. 13, an inkjet dispenser 1104a that supplies the etchant to the outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. The first line 1118a contains an etchant of uniform concentration or molar concentration, and a quenching chemical of uniform concentration is provided in the second line 1120a. Each of the first line 1118a and the second line 1120a includes valves 1122a, 1124a, and the valves 1122a, 1124a selectively open to regulate or change the flow passing through the valves 1122a, 1124a, i.e., the flow of the etchant (line 1118a, valve 1122a) and the flow of the quenching chemical (line 1120a, valve 1124a) that flows into and through the droplet dispensing outlet 1110a of the outlet nozzle 1108a. The quenching chemical reacts with the etchant preferentially over the etchant reacting with the photoresist layer 30, so that the etchant is consumed by the quenching chemical and the etching of the photoresist layer 30 stops.

[0032] To fabricate the photoresist wedge 50 using the present system, an etchant is discharged through line 1118a to the outlet nozzle 1108a to cover the entire area where the photoresist wedge 50 is to be formed. Immediately thereafter, a quenching chemical is discharged at a position around the forming recess 50a. The region of the recess 50 to be formed that is located inside the outer periphery of the recess 50 to be formed and becomes gradually deeper will receive the quenching chemical at individual time intervals between the dispensations of the quenching chemical at gradually later times, and finally, the deepest point of the forming recess 50a will receive the quenching chemical. The position of the photoresist layer 30 inside the outer periphery of the forming recess 50a receives the quenching chemical at a predetermined time based on the desired thickness of the recess 50a at that position by the movement of the stage 1114 for positioning individual regions of the photoresist layer 30 under the flow of the droplets 1106 of the quenching chemical, thereby leaving the desired thickness of the photoresist layer 30 to provide the photoresist wedge 50. When the entire surface of the recess 50a of the photoresist layer 30 is quenched, the surface 50 of the photoresist is washed with a neutral liquid such as deionized water dispensed by the rinse nozzle 1126, and etched debris, any residual etchant, the quenching chemical, and any by-products formed there are removed. Thereafter, the optical device 10 on which the photoresist wedge 50 is formed is removed from the stage 1114 and placed in a cleaning and drying station 1128 having a spin rinse chuck 1130, and is further cleaned and dried.

[0033] In a second aspect of fabricating the photoresist wedge 50, the etchant is dispensed in a temporally varying manner across the region where the recess 50a is to be formed. As the dispensed etchant reacts with the underlying material, the etchant is consumed. In selected portions of the photoresist layer 30, more droplets 1106 (an increase in droplet density) are ejected into the deeper etching region to achieve a deeper etching of the photoresist layer 30, and fewer droplets (a lower droplet density) are ejected into the shallower region where the recess 50a is to be formed. In this aspect, the droplets 1106 of the inkjet dispenser 1104 have a uniform etchant concentration. The etchant reacts with the photoresist at the position where it contacts the photoresist layer 30 until the chemical reaction is exhausted, i.e., until the etchant is almost consumed, and a limited amount of etching is performed for each droplet. Thus, in the region with fewer droplets, the etching directed inwardly into the photoresist layer 30 is smaller, and in the region where more droplets are ejected, the etching directed inwardly into the photoresist layer 30 is larger. The etchant is ejected in a sequentially programmed manner at a rate that is not faster than its consumption rate due to its reaction with the photoresist layer 30, where the stage 1114 moves the photoresist layer 30 under the flow of the droplets 1106 to selectively replenish the etchant at the desired location on the photoresist layer 30. More droplets 1106 are dispensed in the region where the recess 50a is formed deeper by the photoresist 30, and fewer droplets are dispensed in the region where the recess 50a is formed shallower by the photoresist 30, where the maximum number of droplets 1106 are dispensed upward across the region where the recess 50a is deepest, and the fewest droplets are dispensed at the periphery of the recess 50a where the recess is shallowest.Stage 1114 first moves the photoresist layer 30 under the exit nozzle 1108 to cover the entire area where the recess 50a, and thus the wedge 50, is to be formed. An area that gradually becomes smaller centered on the deepest location of the formed recess 50a receives the etchant, and the stage finally stops to position the droplet dispensing outlet 1110 above the deepest position of the formed recess 50a. There, additional droplets 1106 of the etchant are dispensed to complete the etching of the photoresist layer 30 for forming the wedge 50. By this method, the portion of the photoresist layer 30 where the shallower side surface of the wedge 50 and the recess 50a is formed receives fewer droplets 1106 of the etchant and is etched by those fewer droplets 1106, and the deepest region of the recess 50a formed inwardly in the photoresist layer 30 receives the most droplets 1106, where the photoresist layer 30 is recessed deepest. Thereafter, the surface of the photoresist layer 30 including the wedge 50 is cleaned with deionized water dispensed by the cleaning nozzle 1126 to remove the etched debris, the etchant, the quenching chemicals, and any by-products formed there. Thereafter, the optical device 10 is removed from the support 1114, placed in the cleaning and drying station 1128, and further cleaned and dried.

[0034] In a third aspect, the etchant is released at a variable concentration or molarity across the area where the wedge 50, and thus the recess 50a, is to be formed. As the etchant reacts with the underlying material of the photoresist layer 30, the etchant is consumed. To achieve a deeper etch within a desired area of the photoresist layer 30, droplets 1106 of higher etchant concentration or molarity are released into the area to be etched deeper, and droplets of lower concentration (diluted droplets) are released within the area to be etched less, i.e., within the area of the shallower recess 50a. To achieve this, the dispenser 1104 that supplies the etchant to the outlet nozzle 1108a is connected to two different supply lines. The first line 1118a contains an etchant of uniform concentration or molarity, and a diluent, such as deionized water, is supplied in the second line 1120a. Each of the first line 1118a and the second line 1120a includes valves 1122a, 1124a, which are selectively opened to regulate or vary the variable flow passing through the valves 1122a, 1124a, i.e., the flow of the etchant (line 1118a, valve 1122a) and the flow of the diluting chemical (line 1120a, valve 1124a) that enters and passes through the droplet dispensing aperture 1110a of the outlet nozzle 1108a. By the relative flow of the diluent and the etchant, etchants of various concentrations are obtained for each droplet. The dispensed etchant 1116 reacts at the position where it contacts the photoresist layer 30 until the chemical reaction is exhausted, and a limited amount of etching is performed for each droplet, with less etching occurring where droplets 1006 of lower etchant concentration are dispensed. The etchant is released in a sequentially programmed manner at a rate that is not faster than the rate of consumption by the material 12 of the photoresist layer 30, where the stage 1114 moves the optical device 10 under the flow of the droplets 1106.The area where the etchant is dispensed extends over the entire area where the photoresist wedge 50, and thus the recess 50, is to be formed. Here, the droplet dispensing outlet 1110 of the outlet nozzle 1108a discharges the droplets 1106 with an increasing ratio of the etchant to the diluent from the position on the outer periphery of the area of the photoresist layer 30 to be etched to the position on the photoresist layer 30 where the deepest etching in the photoresist layer 30 is performed. At this location, the diluent is not discharged together with the etchant. Therefore, the shallower side of the recess 50a receives the etchant droplets 1106 with a lower concentration, and the deepest region of the recess 50a formed within the photoresist layer 30 where the photoresist wedge 50 is formed receives the droplets 1106 with the highest concentration and is thus etched deepest. Thereafter, the surface is cleaned with deionized water dispensed by the rinse nozzle 1126, and the etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Thereafter, the optical device 10 is removed from the support 1114, placed in the cleaning and drying station 1128, and cleaned and dried.

[0035] In a fourth aspect, the etchant is dispensed as droplets of various sizes across the region of the photoresist layer 30 where the photoresist wedge 50 is to be formed. As the etchant reacts with the underlying material of the photoresist layer 30, the etchant is consumed. To achieve a deeper etch into the photoresist layer 30, larger droplets are dispensed within the deep etch region and smaller droplets are dispensed within the shallower wedge region. To achieve this, the inkjet printer 1100 includes an inkjet dispenser 1104 that can dispense smaller or larger droplets that are dropped as droplets 1106 through the droplet dispensing outlet 1010 of the exit nozzle 1108. The etchant reacts at the position where it contacts the photoresist layer 30 until the chemical reaction is exhausted, and a limited amount of etching is performed for each droplet, and less etching occurs where smaller etchant droplets 1106 are dispensed. Here, preferably, a material with a higher viscosity as the etchant, or the medium of the etchant, is utilized to reduce the flow of the etchant from the position on the photoresist where the etchant is dispensed, whereby a thicker layer of the etchant can be present over the deepest part of the formed recess, and the thicker layer of the etchant tapers in thickness towards the thinnest part of the etchant present at the positions surrounding the formed recess 50a. The size of the droplets 1106 gradually increases from the outer periphery of the recess 50a to be formed to the most deeply etched position. Thus, the shallower sides of the region where the recess 50a is formed receive smaller etchant droplets 1106, and the deepest region of the recess 50a to be formed receives the largest droplets, and thus at that position, the photoresist layer 30 is etched the deepest. Thereafter, the surface of the photoresist layer 30 with the wedge 50 formed thereon is cleaned with deionized water dispensed by the cleaning nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed therein are removed. Thereafter, the optical device 10 is removed from the support 1114 and placed within the cleaning and drying station 1128, where it is cleaned and dried.

[0036] As a result, using the optical device 10 having the flat optical layer 19 including the photoresist layer 30 provided with the 2D wedge 50c, as shown in FIG. 5C, it is possible to form the 2D wedge 50c in the optical layer 19. The photoresist layer 30 is used as a masking pattern for anisotropic plasma etching of the device, and as shown in FIG. 5C, the contour of the wedge 50 is transferred to the optical layer as the optical layer wedge 50b. By this reactive ion etching, both the materials of the photoresist layer 30 and the optical layer 19 are removed, and the pattern of the wedge 50c as shown in FIG. 5C is etched into the optical layer 19. Due to the change in thickness caused by the 2D wedge 50 in the photoresist 30, a larger etching of the optical layer 19 is performed under the place where the thickness of the photoresist 30 is thinner, that is, within the deeper region of the recess 50a, and a smaller etching is performed within the optical layer under the region covered more thickly by the photoresist 30, that is, within the shallower region of the recess 50a and within the non-recessed region of the photoresist 30. By the resulting etching, the pattern of the wedge 50 of the photoresist is transferred to the optical layer 19, and the optical device 10 including the 2D optical layer wedge 50c in the optical layer 19 is obtained. Then, the remaining photoresist layer 30 is removed by etching, and the obtained device is cleaned by a wet cleaning process or the like.

[0037] In FIGS. 5D and 5E, schematic side views of the device 10 are shown for explaining a different series of operations for fabricating the optical device 10 including the 2D optical layer wedge 50b within the optical layer 19 of the optical device 10. The photoresist layer 30 is not provided in this optical device 10. In this aspect of forming the optical layer wedge 50b in the optical layer 19, all four aspects of the process of forming the features described with respect to FIGS. 5A - 5C are used, except that the material being etched is the underlying waveguide material and the etchant is specific to the waveguide material.

[0038] FIG. 6A is a flowchart showing a series of operations for fabricating a 2D optical layer wedge 50b within the optical layer 19 of the optical device 10 in accordance with the series of processes described with respect to FIGS. 5A-5C. First, an optical layer 19 coated with a photoresist layer 30 by a fluidized chemical vapor deposition, physical vapor deposition, spin coating, or other deposition framework is prepared, a wedge 50 is formed in the photoresist 30, and the pattern of the wedge 50 is transferred to the underlying optical layer 19.

[0039] In operation 601, an optical device 10 composed of an optical layer 19 including a photoresist layer 30 is placed or mounted on a stage 1114 within an inkjet wet etching apparatus 1100, and the stage moved in the X and θ directions of FIG. 11 positions a desired location on the photoresist 30 where the wedge 50 is to be formed under the droplet dispensing opening 1010 of the exit nozzle 1008 of the inkjet printer in operation 603. In operation 605, an etchant capable of reacting with (etching) the material of the photoresist layer 30 is released from the droplet dispensing opening. Specifically, in this etchant, the etching rate of the material of the optical layer 19 is about 100 times or more smaller than the etching rate of the photoresist layer 30 exposed to the same etchant.

[0040] The optical device 10 covered with the photoresist layer 30 is placed on the stage 1114, and a photoresist wedge 50 defined by the surface of a recess 50a extending inwardly on the outer surface of the photoresist layer 30 is formed by dispensing wet etching or droplets 1106 of a reactive chemical onto the photoresist layer 30 from one or more exits 1108 of the inkjet device 1104. The contour of the wedge or recess 50a is provided by causing greater etching than where the deepest point of the recess 50a is to be formed and causing gradually smaller etching on the side surface of the recess 50 or in an annular region extending radially outward from the deepest point of the recess 50a.

[0041] In one approach or aspect, in operation 605, an etchant having the same etchant concentration or molarity is uniformly dripped by droplets 1106 from injection nozzle 1108 across the entire region where the wedge 50 is to be formed. Immediately thereafter, a quenching chemical is released in operation 611 around the region where the wedge is being formed, and then sequentially released to additional regions of the surface of the photoresist 30, and finally, the quenching chemical is released over the deepest portion of the recess 50a to be formed. When the surface of the photoresist layer 30 receives the quenching chemical and the etching reaction is quenched, then in operation 621, the surface of the photoresist 30 is washed with a neutral solution such as deionized water, and the etched debris, any remaining etchant, the quenching chemical, and any by-products formed there are also removed. In operation 631, the optical device 10 with the wedge 50 formed in the photoresist 30 is removed from the stage 1114, and in operation 641, dried within a cleaning and drying station 1128, the surface of the photoresist layer with the 2D wedge 50c formed is further rinsed and then dried.

[0042] In the second aspect, the contour of the recess 50a dispenses more droplets 1106 (increase in droplet density) into the region of the photoresist layer 30 of the region to be etched deeper until the chemical reaction is exhausted, while releasing fewer droplets 1106 (decrease in droplet density) having a uniform etchant concentration to contact on the photoresist layer 30. In the region where there are fewer droplets, smaller etching is performed inwardly on the photoresist layer 30, and in the region where more droplets are released, larger etching is performed inwardly on the photoresist layer 30. The positioning of the droplets 1106 is realized by the movement of the stage 1114 under the flow of the droplets 1106, and thus the movement of the photoresist layer 30, so that the etchant is selectively replenished at individual locations on the photoresist layer 30. Once the recess 50a is formed, in operation 623, the surface of the photoresist layer 30 including the wedge 50 is cleaned with a neutral liquid such as deionized water, and the etched debris, etchant, quenching chemicals, and any by-products formed therein are removed. Thereafter, in operation 633, the optical device 10 is removed from the support 1114, and in operation 643, it is placed in the cleaning and drying station 1128 and cleaned. Then, the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and dried.

[0043] In a third aspect, the etchant is discharged with a varying concentration or molar concentration across the region where the depression 50a of the photoresist layer 30 is formed. In operation 615, droplets with a higher etchant concentration or molar concentration are discharged into the region of the photoresist layer 30 to be etched deeper, and droplets with a lower concentration (diluted droplets) are discharged within the region to be etched less severely, i.e., within the shallower wedge region. Thereafter, the surface of the photoresist 30 in which the depression 50a is formed is cleaned with a neutral liquid such as deionized water in operation 625. Thereafter, in operation 635, the optical device 10 is removed from the support 1114 and placed in the cleaning and drying station 1128 for cleaning in operation 645. Thereafter, the surface of the photoresist layer 30 in which the 2D wedge 50c is formed is further rinsed and dried.

[0044] In a fourth aspect, the etchant is discharged in droplets of various sizes across the region of the photoresist layer 30 in which the wedge 50c is formed. In operation 617, larger droplets are discharged into the deep etching region of the depression 50a being formed, and smaller droplets (diluted droplets) are discharged into the shallower region of the depression 50a being formed, generating the wedge 50c, where the size of the droplet 1106 is changed by the inkjet dispenser 1104 within the exit nozzle 1108. Thus, the shallower side of the region in which the depression 50a is formed receives smaller etchant droplets 1106, and the deepest region of the depression 50a being formed receives the largest droplets, and thus at that position, the photoresist layer 30 is etched deepest. Thereafter, in operation 627, the surface of the photoresist layer 30 in which the photoresist wedge 50 is formed is cleaned with deionized water, removing the etched debris, etchant, quenching chemicals, and any by-products formed therein. Thereafter, in operation 637, the optical device 10 is removed from the support 1114 and placed in the cleaning and drying station 1128 for cleaning in operation 647. Thereafter, the surface of the photoresist layer 30 in which the 2D wedge 50c is formed is further rinsed and dried.

[0045] In this way, the obtained optical device 10 has a flat upper surface of the optical layer 19 and is formed to include a photoresist layer 30 provided with a wedge 50. At this point, in operation 650, the shape of the wedge 50c of the photoresist layer 30 is transferred to the underlying optical layer 19. At this time, the photoresist layer is used as a mask for anisotropically plasma etching a part of the optical layer to transfer the corresponding wedge 50b.

[0046] FIG. 6B is a flowchart showing a series of operations for directly fabricating a wedge 50b in the optical layer 19 of the optical device 10 according to the series of processes described with respect to FIG. 1. First, an optical layer 19 with a uniform thickness is prepared.

[0047] Here, in operation 661, an exposed optical device 10, that is, at least a part of which is not covered by other film layers, is provided and placed on a stage 1114 within the range of an inkjet wet etching apparatus 1100. In operation 663, the stage is moved in the X direction and the θ direction of FIG. 11 to position a desired position on the device 10 where a 2D wedge 50b is to be formed under the inkjet exit nozzle 1008. In operation 665, an etchant capable of reacting with (etching) the material of the optical layer 19 is discharged from a dispensing nozzle.

[0048] Here, the wedge is etched directly on the exposed surface of the optical layer 19. Examples of possible layer materials for the optical layer 19 and etchants appropriately paired with them include the following pairs, namely, SiO2 material and DHF etchant, Si3N4 material and HF or H3PO4 as an etchant, TiO2 material and SC1 etchant, carbon-based material and an organic solvent or a photoresist removal etchant, and aSI (amorphous silicon) material using a KOH etchant. The recess can be etched to form the optical layer 50b in various different ways.

[0049] In one approach or aspect, after the substrate is provided and attached to the stage 1114 in operation 601, in operation 663, the area where the 2D wedge 50b is to be formed is positioned under the droplet dispensing outlet 1110 of the exit nozzle 1108 of the inkjet dispenser 1104. In operation 605, an etchant having the same etchant concentration or molar concentration is uniformly dropped by the droplets 1106 from the injection nozzle 1108 over the area where a recess for forming the wedge 50b of the optical layer is to be formed. In operation 665, the etchant is discharged to the exit nozzle 1108a via the first line 1118a so as to cover the entire area where the optical layer wedge 50 is to be formed. Immediately thereafter, a quenching chemical is discharged to the periphery of the area, where the optical layer wedge 50b is formed in operation 671. The position of the optical layer 19 inside the outer periphery of the optical layer wedge 50b being formed receives the quenching chemical by the movement of the stage 1114 for arranging individual areas of the optical layer 19 under the flow of the droplets 1106 of the quenching chemical at a predetermined time when the optical layer wedge 50b has a desired thickness of the optical layer 19 at that position. When the entire surface of the area of the optical layer 19 where the optical layer wedge 50b is formed is quenched, in operation 681, the surface is then washed with a neutral liquid such as deionized water dispensed by the rinse nozzle 1126, and etched debris, any residual etchant, the quenching chemical, and any by-products formed there are removed. Next, in operation 691, the optical device 10 with the wedge formed is removed from the stage 1114. In operation 692, it is placed in the cleaning and drying station 1128 having the spin rinse chuck 1130, and the surface of the optical layer 30 where the 2D wedge 50c is formed is further rinsed and dried.

[0050] In a second aspect, to form the optical layer wedge 50b, in the region where the optical layer wedge 50b is to be formed, a deeper etching is required, which is achieved by dispensing more droplets onto the optical layer 19 at the above positions (increase in droplet density), while in the shallower region of the optical layer wedge 50b to be formed, fewer droplets (decrease in droplet density) are dispensed onto the optical layer 19. In operation 673, droplets of the inkjet dispenser 1104 with a uniform etchant concentration are dispensed and brought into contact with the optical layer 19 until the chemical reaction between the droplet chemical and the optical layer is exhausted. In the region with fewer droplets, a small etching is performed inwardly on the optical layer 19, and in the region with a greater droplet discharge, a greater etching is performed inwardly on the optical layer 19. Thereafter, in operation 683, the surface of the optical layer 19 including the newly formed optical layer wedge 50b is cleaned with a neutral liquid such as deionized water dispensed by the cleaning nozzle 1126, and the etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Thereafter, in operation 693, the optical device 10 is removed from the support 1114, and in operation 694, it is placed in the cleaning and drying station 1128. Then, the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and dried.

[0051] In a third aspect, across the region where the optical layer wedge 50b is to be formed, the etchant is released at various concentrations or molarities. In operation 675, droplets with a higher etchant concentration or molarity are released into the region of the optical layer 19 that is etched deeper, and lower concentration droplets 1106 (diluted droplets) with a lower content of etchant or reactant are released within the region that is etched less severely, i.e., within the shallower optical layer wedge 50b region. Then, in operation 685, the surface of the optical layer 19 including the wedge 50b here is washed with a neutral liquid such as deionized water dispensed by the rinse nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Then, in operation 695, the optical device 10 is removed from the support 1114 and, in operation 696, placed within the wash and dry station 1128, and then the surface of the photoresist layer 30 where the 2D wedge 50c is formed is further rinsed and then dried.

[0052] In a fourth aspect, etchant droplets having the same reactant concentration or etchant concentration but different sizes are released onto various portions of the region of the optical layer 19 where the optical layer wedge 50b is to be formed. In operation 677, larger droplets are released within the deeper etching region, and smaller droplets are released within the region of the shallower 2D wedge 50b, where the size of the droplets is changed by the inkjet dispenser 1104. The shallower side of the region where the recess for forming the wedge is formed receives the smaller etchant droplets 1106, and the deepest region of the recess formed to form the optical layer wedge 50b receives the largest droplets, and thus at that position, the optical layer 19 is etched deepest. Thereafter, in operation 687, the surface of the optical layer 19 on which the optical layer wedge 50b is formed is cleaned with a neutral liquid such as deionized water dispensed by the cleaning nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed thereon are removed. Thereafter, in operation 697, the optical device 10 is removed from the support 1114, and in operation 698, it is placed within the cleaning and drying station 1128, and then the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and then dried.

[0053] Referring to FIGS. 7A and 7B, a schematic side view of the optical device 10 is shown, including a portion of the upper encapsulation layer 12 (FIG. 7A) and an opening 71 (FIG. 7B) in the encapsulation layer 12 formed by selectively removing a portion of the encapsulation layer by inkjet etching, where the device 10 is useful as a waveguide for virtual reality imaging and other applications as described hereinabove. Here, the optical device 10 includes an opening 71 in the encapsulation layer 12 over the incoupler 15, which is here formed using the inkjet dispenser 1004 to dispense an etchant to selectively and locally remove material from the encapsulation layer 12 to locally form the opening 71 in the encapsulation layer 12 and expose the optical layer 19 below the encapsulation layer 12.

[0054] To form an opening on the surface of the encapsulation layer 12, an optical device 10 having an encapsulation layer 12 of uniform thickness as shown in FIG. 7A is attached to the movable stage 1114 of the inkjet printer 1100 of FIG. 11. The stage 1114 is positioned under the droplet dispensing outlet 1108 of the inkjet dispenser 1104 to etch the encapsulation layer 12 and form an opening 71 in a desired region of the encapsulation layer 12, here on top of the incoupler 15. Here, the side of the encapsulation layer 12 faces the device table of the inkjet etching apparatus. The stage 1114 rotates and moves in the X direction to position individual portions of the position on the device 10 where the opening 71 is to be formed under the droplet dispensing outlets 1110 of one or more inkjet dispensers 1104. The outlet nozzle 1108 facing the surface of the stage 1114 is located at a distance greater than the thickness of the optical device 10 from the droplet dispensing opening 1010 of the outlet nozzle 1008 of the inkjet nozzle, and the distance between the nozzle outlet and the surface of the encapsulation layer 12 of the optical device 10 is about 2 to 5 mm.

[0055] Here, the opening 71 in the encapsulation layer exposes the optical layer 19 below within the scope of its outer periphery, and the reactant or etchant for removing the encapsulation layer material should be highly selective for etching the encapsulation layer and the material forming the optical layer 19. Here, the incoupler 15 of the optical layer 19 has a lattice of nanopillars 19a in the region 19b of the encapsulation layer 12 material extending between them. Thus, when the upper portion of the encapsulation layer 12 is removed, the portion 19b will be removed or can be selectively removed. Examples of possible layer materials for the encapsulation layer 12 and appropriately paired etchants for forming the opening 71 include the following pairs, namely, SiO2 material and DHF etchant, Si3N4 material and HF or H3PO4 as the etchant, TiO2 material and SC1 etchant, carbon-based material and organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using KOH etchant. Etching the gap 71 can be done in a variety of different ways.

[0056] To form the opening 71, since the etchant is selectively chosen to preferably etch the encapsulation layer material highly with respect to the etching of the materials of the substrate 21 and the optical layer 19, the material under the optical layer 19 and the substrate 21 on which the optical layer 19 is provided function as an etch stop layer, Thereby, the encapsulation layer 12 on the incoupler 15 and the region 19b in the encapsulation layer 12 are removed without adversely affecting the grating 19b or the outer surface of the optical layer 19.

[0057] To form the opening 71, the etchant is uniformly dropped from the droplet dispensing outlet 1010 of the inkjet dispenser 1104 over the entire region where the opening 71 is to be formed, and etched through the encapsulation layer 12 on the ink coupler 15. Further, if desired, when the surface of the optical layer 19 is exposed, the etching by the etchant can be continued or the droplet 1106 of the etchant can be added to remove the portion 19b within the ink coupler 15. When the etching is completed (here the result is shown in FIG. 7B where the portion 19b of the inkjet coupler 15 is removed), the reaction can be quenched, for example, by supplying a quenching chemical through the second line 1120b in FIG. 13 to neutralize the etchant and thereby stop the etching. Here, the etchant to be dispensed through the droplet dispensing outlet 1110 of the inkjet dispenser 1104 is supplied through the line 1120a, or the surface can be rinsed with a neutral liquid such as deionized water dispensed from the rinse nozzle 1126 to remove the etchant and stop the removal process. The quenching chemical can also be dispensed from the rinse nozzle 1126. When rinsed with the neutral liquid from the rinse nozzle, the liquid removes the etched debris, any residual etchant, the quenching chemical, and any by-products formed there. Thereafter, the optical device 10 with the gap 71 formed is removed from the stage 1114 and placed in the cleaning and drying station 1128 having a spin rinse chuck 1130, and further cleaned and dried. Alternatively, if the opening 71 is formed but the region 19b of the encapsulating material remains, the inkjet device 1100 can be controlled to dispense the droplets 1106 of the etchant only over the upper surface of the region 19b rather than over the entire region of the opening 71 to remove the said region 19b of the encapsulating material.

[0058] FIG. 8 is a flowchart showing a series of operations for creating the opening gap 71 in the encapsulation layer 12 on the optical layer 19 of the optical device 10 according to the series of processes described with respect to FIG. 7.

[0059] First, in operation 801, the optical layer 19 coated with the encapsulation layer 12 is placed on the stage 1114, where the encapsulation layer 12 faces upward. Next, in operation 803, the stage 1114 is moved to position the desired location where the opening 71 is to be formed via the encapsulation layer 12 under the droplet dispensing outlet 1110 of the inkjet dispenser 1104. Thereafter, several different strategies can be employed to create the desired opening 71 in the encapsulation layer 12.

[0060] In one embodiment, in operation 805, etchant droplets 1106 of uniform size and uniform etchant concentration are ejected over the entire surface of the encapsulation layer 12 including the area where it is desired to form the opening 71. In operation 811, a quenching chemical is ejected at the locations of the encapsulation layer where the etchant has reached but the opening 71 is not desired. When the depth of the opening is reached, i.e., when the upper layer of the optical layer 19 is exposed, in operation 821, the etching is terminated, for example, by supplying a quenching chemical to the exposed optical layer 19 and the adjacent portion of the encapsulation layer 12 within the opening 71, by supplying a rinse liquid such as deionized water to wash away the etchant, or by a combination thereof. Next, in operation 831, the device is moved to a cleaner and in operation 841, it is washed and dried.

[0061] In other embodiments, in operation 813, etchant droplets of uniform size and uniform etchant concentration are ejected only at the locations of the encapsulation layer 12 where the opening 71 is desired. When the opening depth is reached through the encapsulation layer 12 and the optical layer 19 is exposed there, in operation 823, the etching is terminated, for example, by supplying a quenching chemical to the exposed optical layer 19 and the adjacent portion of the encapsulation layer 12 within the opening 71, by supplying a rinse liquid such as deionized water to wash away the etchant, or by a combination thereof. Next, in operation 833, the device is moved to a cleaner and in operation 843, it is washed and dried.

[0062] In other embodiments, in operation 807, buffer droplets of uniform size and etchant concentration are dispensed over the entire optical device 10 except at the location of the encapsulation layer 12 where the aperture 71 is desired. In operation 815, droplets having a constant concentration of etchant are dispensed over the entire encapsulation layer 12 or at least over a portion of the encapsulation layer 12 that is larger than the region of the aperture 71 being formed. When the depth of the aperture is reached, i.e., when the optical layer 19 within the aperture 71 is exposed, in operation 825, the etching is terminated by supplying a quenching chemical to the aperture 71 and the adjacent portion of the encapsulation layer 12, by supplying a rinse liquid such as deionized water to flush the etchant, or by a combination thereof, etc. Next, in operation 835, the device is moved to a cleaner and in operation 845 is washed and dried.

[0063] Referring to FIGS. 9A and 9B, a schematic side view of the optical device 10 is shown, including an abnormal portion in the film layer or in the thickness of the film layer (FIG. 9A), and a smoothed abnormal portion in the thickness of the encapsulation layer (FIG. 9B). The optical device 10 of FIG. 9A includes an abnormal thickness portion 91 in the encapsulation layer 12, and this abnormal portion 91 is here corrected using an inkjet wet etching device 1100 that dispenses an etchant to selectively and locally remove material from the encapsulation layer to form the smooth horizontal surface of the encapsulation layer 12 of FIG. 9B.

[0064] To correct an abnormal portion in thickness, here the abnormal portion 91, or an undesirable extension of the encapsulation layer 12 above a desired upper plane, an extension that extends on the surface of the encapsulation layer 12, an optical device 10 having the abnormal portion 91 is attached to the movable stage 1114 of the inkjet printer 1100 of FIG. 11. The printer 1100 here functions as a local dispenser of an etchant or reactant to the encapsulation layer 12 of the device 10, capable of removing or etching away individual portions of the material of the encapsulation layer 12. The printer 1102 is supported on its base 1112 and includes a table 1102 movable in the X direction relative to the base 1112, and at least one inkjet type dispenser 1104, here four such dispensers 1104a - 1104d. Each of the dispensers 1104a - 1104d is configured to dispense droplets 1106 of a liquid material and has an outlet nozzle 1108 that selectively faces the table 1102. The stage 1114 is rotatably coupled to the table 1102 via a shaft (not shown) connected to a stepper motor (not shown) within the table 1112, for example, and the stage 114 is rotatable about its center 1116 in the θ direction of FIG. 11. To perform etching of the dielectric layer encapsulation layer 12 to remove the abnormal portion 91 in thickness within a desired region of the encapsulation layer 12, i.e., here across the abnormal portion 91 in the thickness of the device 10, the stage 1114 is positioned under the outlet 1108 of the inkjet dispenser 1104 of the droplet dispensing outlet 1110 of the inkjet etching apparatus 1100. Here, the side of the encapsulation layer 12 faces the device table of the outlet nozzle 1108 of the inkjet etching apparatus, and the stage 1114 is rotated and moved in the X direction to position individual portions or positions on the device 10 under the outlet 1108 of one or more inkjet dispensers 1104, the individual portions or positions where the abnormal portion is formed and which are to be removed.The exit nozzle 1008 facing the surface of the stage 1114 is located at a distance greater than the thickness of the optical device 10 from the droplet dispensing opening 1010 at the exit of the exit nozzle 1008 of the inkjet nozzle, and the distance between the nozzle exit and the surface of the encapsulation layer 12 of the optical device 10 is about 2 to 5 mm.

[0065] In order to correct the abnormal portion 91 in the thickness of the outer surface of the encapsulation layer 12 by removing the protrusion without leaving a large depression in the underlying encapsulation layer 12, wet etching or droplets 1106 of a reactive chemical are dropped from one or more outlets 1108 of the inkjet device 1104 onto the protrusion 91. Examples of possible layer materials for the encapsulation layer 12 and the etchants appropriately paired with them include the following pairs, namely, SiO2 material and DHF etchant, Si3N4 material and HF or H3PO4 as the etchant, TiO2 material and SC1 etchant, carbon-based material and organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using a KOH etchant. The etching of the abnormal portion 91 of the 2D wedge 11 can be performed in the film layer and can be carried out in various different ways.

[0066] Here, imaging cameras 1130 and 1132 of the inkjet device 1100 are provided. Using these imaging cameras 1130 and 1132, the position of the abnormal portion 91 on the encapsulation layer 12 is identified, and the inkjet device 1100 can position the abnormal portion 91 directly below the droplet dispensing outlet 1110. As a result, the droplets of the etchant released fall onto the abnormal portion 91 rather than on the surrounding encapsulation layer 12. Further, the imaging cameras 1130 and 1132 can be used together with a control device (not shown) to determine the height of the abnormal portion and the relative heights of various portions of the abnormal portion. While the abnormal portion 91 is being etched away by the application of droplets 1106 of the etchant, the contour and position of the abnormal portion 91 are monitored using the cameras 1130 and 1132, and the stage 1114 can accurately position the abnormal portion 91 below the droplet dispensing outlet 1110, ensuring that the droplets 1106 fall onto the abnormal portion 91 and onto the portion of the abnormal portion 91 that extends farthest above the otherwise flat and uniform surface 93 of the encapsulation layer 12 rather than on an adjacent portion of the encapsulation layer 12. As shown in FIG. 9B, when the abnormal portion 91 is removed down to an otherwise uniform surface 93 of the encapsulation layer, the surface of the encapsulation layer 12 and the exposed portion of the optical layer 19 are rinsed, for example, with a neutral liquid such as deionized water dispensed through the rinse nozzle 1126 using the quenching chemical dispensed by the inkjet dispenser 1124 and the droplet dispensing opening 1110, or rinsed with the quenching chemical, and then, for example, a neutral liquid wash using deionized water is performed to end the etching. Thereafter, the device is removed from the stage and installed in a cleaning and drying station 1128 for cleaning and drying of the device.

[0067] FIG. 10 is a flowchart providing a series of operations used to remove an abnormal portion 91 extending on the surface 93 of a film layer such as the encapsulation layer 12. First, in operation 1001, the device 10 including the abnormal portion is positioned on the stage 1114 of the inkjet etching apparatus 1100. Next, in operation 1003, the position of the abnormal portion on the encapsulation layer is confirmed using cameras 1130, 1132, and the stage 1114 is moved to position the abnormal portion under the droplet dispensing outlet 1110 of the inkjet dispenser 1104 in operation 1003. Next, similar to the process for creating the 2D wedge described in FIG. 2, in operation 1005, the droplets of the etchant are dispensed only onto the surface of the protrusion. The droplets are ejected using the same four strategies described in FIG. 2 and one new additional strategy in operation 1019. The above strategies include the following, namely, removal of the abnormal portion 91 by quenching modification described in operations 1011 - 1041, removal of the abnormal portion 91 by droplet density modification described in operations 1013 - 1043, removal of the abnormal portion 91 by concentration modification described in operations 1015 - 1045, and removal of the abnormal portion 91 by droplet size modification described in operations 1017 - 1047. The above etching procedure follows the same pattern for forming a larger or smaller etch to the desired resulting structure. When creating the 2D wedge, the wedge can be etched on the already flat surface of the encapsulation layer 12, and when correcting the abnormal portion, removing the abnormal portion 91 to generate a flat and uniform surface 93 of the encapsulation layer 12 can be the desired result. Thus, here, the droplets 1106 of the etchant are continuously deposited onto the portion of the abnormal portion 91 that extends farthest from the desired flat and uniform surface 93 below, and these positions will change as the abnormal portion is removed. In operation 1019, etchant droplets of uniform size, density, and concentration are ejected at the most protruding point of the abnormal portion 91 on the desired flat and uniform surface 93 of the encapsulation layer 12, and this most protruding point may or may not be the center of the abnormal portion.While etching continues, cameras 1130 and 1132 locate the most protruding abnormal portion on the desired flat and uniform surface 93 of the encapsulation layer 12, and the stage 1114 of the inkjet etching apparatus 1100 is moved so that the most protruding position of the abnormal portion 91 is positioned under the droplet dispensing outlet 1110 of the inkjet dispenser 1104. Thereafter, a sequence of redispensing droplets, locating the most protruding portion of the abnormal portion, and dispensing the droplets 1106 at that position is repeated until the abnormal portion 91 and the desired flat and uniform surface 93 of the encapsulation layer 12 are coplanar. When this flatness is achieved, in operation 1029, the etching is terminated, for example, by supplying a quenching chemical to the abnormal portion 91 and adjacent portions of the encapsulation layer, by supplying a rinse liquid such as deionized water to wash away the etchant, or by a combination thereof, etc. Next, in operation 1039, the apparatus is moved to a cleaner, and in operation 1049, it is washed and dried.

[0068] Referring to FIGS. 12A and 12B, schematic side views of an optical device 10 including a uniform encapsulation layer 12 (FIG. 12A) and an optical device 10 in which a 1D wedge 121 (FIG. 12B) is formed in the encapsulation layer 12 are shown. The optical device 10 of FIG. 12A includes an encapsulation layer 12, where the 1D wedge 121 is fabricated using an inkjet wet etching apparatus 1100 for dispensing an etchant to selectively and locally remove material from the encapsulation layer to form a smooth and angled surface of the encapsulation layer 12 of FIG. 12B. Here, in contrast to the 2D wedge structure described earlier herein, where the depth of the surface features etched in the Z direction on the surface of the layer varies in both the X and Y directions, here, the depth of the surface etched in the Z direction on the surface of the layer varies only in one of the X and Y directions, resulting in a lamp-shaped feature having a planar outer surface, i.e., a simple 1D wedge. As described herein, the depth of the feature varies only in the X direction and is constant over any Y direction, and the depth of the feature at adjacent Y-direction positions adjacent to each other in the X direction changes. This is achieved by performing the same material removal over each Y-direction segment of the feature and increasing or decreasing the material removal at adjacent Y-direction positions of the feature. As described herein, this can be achieved in several ways, including applying a blanket material remover, i.e., an etchant, to the entire area of the surface where the wedge is to be formed, and selectively quenching the reaction over the Y direction of the surface, where the Y direction of the surface is from the X o end starting and the X of the region e ending at the end, where a plurality of n regions extend in the Y direction over the region where the feature is to be formed. Here, for example, individual regions extending in the Y direction over the region where the 1D wedge 121 is to be formed having the same quench timing, or the exposure of the underlying material during the etchant period (each adjacent region having a different quench timing), or the exposure of the underlying material during the etchant period is enabled such that the individual regions Y1 - Y in the X direction nIts width is selected. In FIG. 12C, region Yo has the earliest quench timing. In other words, it is quenched before any other region is quenched. The next region Y1 has the next earliest quench timing, and each adjacent region Y2 - Y n has a corresponding longer quench timing. As a result, the Z - direction depth of region Y o is shallower than the Z - direction depth of region Y1. The Z - direction depth of region Y1 is shallower than the Z - direction depth of region Y2. The Z - direction depth of region Y2 is shallower than the Z - direction depth of each subsequent region Y3 - Y n and finally, the Z - direction depth of region Y n-1 is shallower than the Z - direction depth of region Y n . In this way, a feature is formed that has an inclined outer surface extending inwardly toward the surface of the encapsulation layer 12. The smaller the respective X - direction width of the individual regions Y1 - Y n , the smoother the transition from the depth of region Y1 to the depth of region Y n . As a result, as the width of each Y - region in the X - direction approaches 0, the outer surface of the 1D wedge 121 becomes more planar.

[0069] In other embodiments, the 1D wedge 121 can be formed by varying the density of the dispensed etchant droplets in the X - direction while maintaining the same density of droplets in the Y - direction at each X - position. As the etchant is consumed by reaction with the material beneath where the wedge is to be formed, the etching rate decreases and can reach 0 in regions where fewer droplets are dispensed, but in regions where the wedge feature is etched deeper into the layer, i.e., where more droplets are dispensed than in the adjacent Y - regions in the X - direction, the etching continues inwardly into the layer and a 1D wedge 121 as shown in FIGS. 12B and 12C can be formed. Again, the droplets 1106 can be dispensed within regions Y o - Y n , where the number of droplets within each individual Y - region is the same, but the number of droplets within adjacent Y - regions in the X - direction is different. In this way, a wedge feature having the characteristics of FIGS. 12B and 12C is formed.

[0070] In other embodiments, the 1D wedge 121 changes the etchant concentration in the droplets dispensed within adjacent Y regions in the X direction, but here again the region Y o ~Y n is formed by maintaining the etchant concentration of the droplets 1106 in each of the regions Y o constant in the Y direction. Similarly, the size of the etchant droplets can be varied across the region of the wedge 121 being formed, where the etchant concentration in the droplets is the same. Thus, the smallest droplets are deposited across the entire region Y o ~Y n and the size of the droplets is gradually increased within each subsequent region Y

[0071] FIG. 13 is a flowchart showing a series of operations for fabricating a 1D wedge 121 within the encapsulation layer 12 of the optical device 10 in accordance with the series of processes described with respect to FIG. 12. First, the optical layer 19 is prepared. However, the encapsulation layer 12 needs to be of a thickness that provides the desired effect for the optical device 10, and thus the 1D wedge 121 can be formed. Here, a processing sequence for forming a 1D wedge in the encapsulation layer 12 will be described.

[0072] In operation 1301, the optical device 10 is placed on the stage 1114, and in operation 1303, it is positioned by the stage 1114 within the inkjet wet etching apparatus 1100 to a desired location on the encapsulation layer 12 beneath the droplet dispensing aperture 1110 of the exit nozzle 1108 of the inkjet dispenser 1104 by movement in the X direction and the θ direction of FIG. 11. In operation 1305, an etchant capable of reacting with (etching) the material of the encapsulation layer 12 is released as droplets 1106 from the droplet dispensing aperture. Preferably, in the above etchant, the etching rate of the material of the optical layer 19 is at least about 100 times lower than the etching rate of the encapsulation layer 12 when exposed to the same etchant.

[0073] In one aspect, in operation 1311, after the etchant is discharged through line 1118a to outlet nozzle 1108a so as to cover the entire area where the wedge profile 11a for forming the wedge 121 is to be formed, immediately thereafter, the quenching chemical is discharged into the area Y0 of the forming wedge profile 11a. The Y regions with larger subscript numbers of the encapsulation layer of the forming wedge profile 11a are then sequentially received by the quenching chemical by the movement of stage 1114 to position the individual regions of the encapsulation layer 12 under the flow 1106 of the droplets of the quenching chemical for a predetermined time. At the above-mentioned predetermined time, the wedge profile 121a is in its position and just enough material has been removed to form the desired thickness of the encapsulation layer 12 of the wedge profile 11a. Here, the amount of material removed is the same in the Y direction and varies in the X direction, and for each length in the X direction, a planar feature extending into the interior of layer 12 in the Z direction is obtained at a constant rate. When the entire surface of the area of the wedge profile 11a of the encapsulation layer 12 is quenched, in operation 1321, the surface is washed with deionized water dispensed by the rinse nozzle 1126, and the etched debris, any residual etchant, the quenching chemical, and any by-products formed therein are removed. In operation 1331, thereafter, the optical device 10 on which the wedge 11 is formed is removed from the stage 1114 and placed in the cleaning and drying station 1128 having the spin rinse chuck 1130 in operation 1341, and is further cleaned and dried.

[0074] In a second aspect, the deeper etching is achieved by dispensing gradually more droplets in adjacent Y regions where the subscript numbers increase in the X direction, while maintaining a constant etchant droplet density in the Y direction of regions Y o ~Y n . Thus, in operation 1313, the minimum density of droplets is deposited over the entire area Y o , and for each subsequent area Y o ~Y nBy sequentially increasing the droplet density, the wedge contours of FIGS. 12B and 12C can be formed by the movement of the stage 1114 downward in the droplet flow 1106, and thus the movement of the encapsulation layer 12. Alternatively, when the viscosity of the droplet is relatively high and does not move significantly from the position where it is dropped onto the encapsulation layer, by passing the wedge contour 121a forming the region of the encapsulation layer 12 once under the droplet dispensing outlet 1010, more droplets 1106 can be dropped at a deeper position of the wedge contour 121a than in the shallower region of the wedge contour 11a. As a result, a thicker layer of the etchant is present above the deeper position of the wedge contour 11a to be formed than in the shallow region of the wedge contour 11a. Thereafter, in operation 1323, the surface of the encapsulation layer 12 including the 1D wedge 121 is cleaned with deionized water dispensed by the cleaning nozzle 1126, and the etched debris, etchant, quenching chemicals, and any by-products formed therein are removed. Thereafter, in operation 1333, the optical device 10 is removed from the support 1114 and, in operation 1343, placed in the cleaning and drying station 1128 and further cleaned and dried.

[0075] In a third aspect, in operation 1305, the etchant is released by droplets 1106 of various etchant concentrations at various positions of the wedge contour 121a to be formed. The droplets are dispensed into adjacent Y regions in the X direction, where again, in the Y direction of the regions Y o ~Y n the etchant concentration of the droplets is maintained constant. Thus, in operation 1315, droplets of the minimum concentration are deposited throughout the region Y o and in each subsequent region Y o ~Y nBy gradually increasing the concentration of the droplets therein, the wedge features of FIGS. 12B and 12C can be formed. Thereafter, in operation 1325, the surface of the encapsulation layer 12 including the 1D wedge 121 is cleaned with deionized water dispensed by the rinse nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Thereafter, in operation 1335, the optical device 10 is removed from the support 1114, and in operation 1345, it is placed in the cleaning and drying station 1128 and further cleaned and dried.

[0076] In a fourth aspect, the etchant released in operation 1305 dispenses droplets of a larger size in adjacent Y regions in the X direction, but in operation 1317, in region Y o ~Y n By maintaining the size of the etchant droplets constant in the Y direction of, a deeper etching is achieved. Thus, droplets of the minimum size are deposited throughout region Yo, and in each subsequent region Y o ~Y n By gradually increasing the size of the droplets therein, the wedge features of FIGS. 12B and 12C can be formed. Thereafter, in operation 1327, the surface of the encapsulation layer 12 on which the 1D wedge 121 is formed is cleaned with deionized water dispensed by the cleaning nozzle 1126, and etched debris, etchant, quenching chemicals, and any by-products formed there are removed. Thereafter, in operation 1337, the optical device 10 is removed from the support 1114, and in operation 1347, it is placed in the cleaning and drying station 1128 and further cleaned and dried.

[0077] In at least some embodiments of this specification, a surfactant is used to modify the etching ability of the aforementioned etching strategy. The surfactant is used to modify the surface energy of the droplet. When the surface energy of the droplet is less than the surface energy of the surface it receives, the droplet spreads. The higher the surface energy of the droplet compared to the surface energy of the surface on which the droplet is dropped, the less the droplet spreads. Thus, here, the local mixing of adjacent droplets on the surface to be etched or on the surface during etching can be changed by selectively adding a surfactant thereto, whereby it becomes possible to fuse the dispensed droplets adjacent to each other or to leave them substantially isolated from each other.

[0078] The foregoing is directed to embodiments of the present disclosure, but other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is defined by the following claims.

Claims

1. A method of forming three-dimensional features inwardly on the surface of a material, comprising: providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material, the liquid material having a reactant capable of removing a portion of the material layer contacted by the droplets by reacting therewith; providing a support configured to support the material thereon, the support and the droplet dispenser being movable relative to each other, and the outlet of the droplet dispenser being positionable over various individual regions of the surface of the material; positioning the surface of the material under the droplet dispenser and dispensing droplets onto individual portions of the surface of the material within a desired region of the material to remove at least a portion of the material within the desired region and form a three-dimensional recess inwardly on the surface of the material; A method comprising the above steps.

2. The method of claim 1, further comprising dispensing droplets of the liquid material in various amounts onto various portions of the desired region.

3. The method of claim 2, wherein the number of droplets dispensed is greater in a deeper region of the three-dimensional feature being formed over the entire length of the desired region.

4. The droplets of the liquid material dispensed from the droplet dispenser have a uniform concentration of the reactant; the droplets of the liquid are dispensed over the entire desired region; a quenching chemical is applied to the desired region over a period of time, and portions of the desired region where more material is to be removed receive the etchant at a later time than portions of the desired region where less material is to be removed.

5. The method of claim 4, wherein the droplets have the same concentration of the reactant.

6. The method of claim 1, further comprising providing droplets having different concentrations of the reactant to various individual portions of the desired region.

7. The method of claim 6, wherein droplets having a higher concentration of the reactant are dispensed to individual portions of the region where the three-dimensional feature being formed is to be deeper, and droplets having a lower concentration of the reactant are dispensed to individual portions of the region where the three-dimensional feature being formed is to be shallower than the deeper portions.

8. The method according to claim 1, further comprising providing droplets of various volumes to various individual portions of the desired region.

9. The method according to claim 8, wherein the droplets of various volumes have the same concentration of the reactant.

10. The method according to claim 8, wherein droplets with a larger volume are dispensed to individual portions of the region where the three-dimensional feature being formed should be deeper, and droplets with a smaller volume are dispensed to individual portions of the region where the three-dimensional feature being formed should be shallower than the deeper portion.

11. The method according to claim 1, further comprising dispensing droplets to form a three-dimensional feature inwardly on the surface of the abnormal feature, wherein the surface of the material is an abnormal feature.

12. The method according to claim 1, wherein the material is disposed to cover a second material thereunder, and the first material is removed within the region, such that the underlying surface of the underlying second material is exposed.

13. A material layer having a three-dimensional feature, providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material, wherein the liquid material has a reactant capable of removing a portion of the material layer in contact with the droplets by reacting therewith, providing a support configured to support the material thereabove, wherein the support and the droplet dispenser are movable relative to each other, and the outlet of the droplet dispenser is positionable above various individual regions of the surface of the material, positioning the surface of the material under the droplet dispenser and dispensing droplets to individual portions of the surface of the material within the desired region to remove at least a portion of the material within the desired region and form a three-dimensional recess inwardly on the surface of the material, A material layer produced thereby.

14. The material layer according to claim 13, further comprising dispensing droplets of the liquid material in various amounts to various portions of the desired region.

15. The droplets of the liquid material dispensed from the droplet dispenser have a uniform concentration of the reactant, and the liquid droplets are dispensed across the entire desired region. The quenching chemical is applied to the desired region over a period of time, and portions of the desired region where more material is to be removed receive the etchant at a later time than portions of the desired region where less material is to be removed, the material layer of claim 13.

16. The material layer of claim 13, further comprising providing various concentrations of the reactant to various individual portions of the desired region.

17. The material layer of claim 13, further comprising providing droplets of various volumes to various individual portions of the desired region.

18. A method of forming a patterned photoresist on a material layer, comprising: providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material; providing a support configured to support the material layer thereabove, the support and the droplet dispenser being movable relative to each other, the outlet of the droplet dispenser being positionable over various individual regions of the surface of the material; providing a first liquid including a photoresist polymer that is dispensable in droplet form from the droplet dispenser; providing a second liquid including a photosensitizer that, when mixed with the polymer, modifies the reactivity of the polymer to electromagnetic energy; positioning the surface of the material under the droplet dispenser and dispensing droplets of the first liquid to individual portions of the first liquid over the entire surface of the material layer, and dispensing droplets of the second liquid only to desired individual regions of the material layer to mix the first liquid and the second liquid within the desired individual regions of the material layer; A method comprising.

19. The method of claim 18, wherein various amounts of the first liquid are dispensed to various portions of the individual region within the individual region.

20. The method of claim 19, wherein a plurality of sublayers of the first liquid are continuously coated on the material layer, the first sublayer and subsequent sublayers on the material layer are formed one above the other, and the portion of the individual region receiving the second liquid increases from the first sublayer to the last sublayer being formed.

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