Method for fabricating two-dimensional wedges and localized encapsulation layers for diffractive optical elements - Patents.com

Abstract

A method of forming three-dimensional features inwardly in a surface of a material is provided, the method comprising: providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material, the liquid material having a reactive substance capable of reacting with and thereby removing portions of a material layer with which the droplets contact; providing a support configured to support the material thereon, the support and the droplet dispenser being movable relative to one another, the outlet of the droplet dispenser being positionable over various discrete areas of the surface of the material; and positioning the surface of the material under the droplet dispenser to dispense droplets onto discrete portions of the surface of the material in desired areas of the material to remove at least a portion of the material in the desired areas and form three-dimensional recesses inwardly in the surface of the material.

Description

[Technical field]

[0001] The present disclosure relates generally to selectively wet etching multi-dimensional features inwardly into a material surface, and more specifically to dispensing discrete droplets of material removal chemistry onto discrete portions of a material surface to form multi-dimensional recessed features within controlled discrete areas of the material surface. [Background technology]

[0002] Three-dimensional features extending inwardly into the surface of a material layer are useful in several applications, such as forming two-dimensional (2D) wedges in the surface of an optical device to create diffractive optical elements, including waveguide combiners and flat optical elements, among other applications. In some cases, such features are created in an optical device to enable in-couplers, out-couplers, or both, to direct light into or out of an optical layer of the optical device. There is a need to more precisely position such features, including reproducible contours, from device to device, without the need to process the substrate to form an etch mask on the substrate using wet removal chemistries, such as wet etchants. Summary of the Invention

[0003] In one aspect, a method of forming three-dimensional features inwardly in a surface of a material includes providing a droplet dispenser including an outlet configured to dispense discrete droplets of a liquid material, the liquid material having a reactive substance capable of reacting with and thereby removing portions of a layer of material with which the droplet contacts; providing a support configured to support the material thereon, the support and the droplet dispenser being moveable relative to one another and the outlet of the droplet dispenser being positionable over various discrete regions of the surface of the material; and positioning the surface of the material under the droplet dispenser to dispense droplets onto the discrete portions of the surface of the material in desired regions of the material to remove at least a portion of the material in the desired regions to form three-dimensional recesses inwardly in 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 liquid material; providing a support configured to support the material layer thereon, the support and the droplet dispenser being movable relative to one another and the outlet of the droplet dispenser being positionable over various discrete areas of a surface of the material; providing a first liquid dispenseable in the form of droplets from the dispenser, the first liquid including a photoresist polymer; providing a second liquid including a photosensitizer, the second liquid including a photosensitizer that when mixed with the polymer modifies a reactivity of the polymer to electromagnetic energy; positioning the surface of the material under the droplet dispenser to dispense droplets of the first liquid onto discrete portions of the entire surface of the material layer; and dispensing droplets of the second liquid only onto the desired discrete areas of the material layer to mix the first liquid and the second liquid within the desired discrete areas of the material layer. [Brief description of the drawings]

[0005] [Figure 1A] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer. [Figure 1B]1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer having a 2D wedge formed therein. [Figure 1C] FIG. 1C is an isometric view of the optical device of FIG. 1B having an optical layer and an encapsulation layer with a 2D wedge formed therein. [Diagram 2] 1B is a flow chart illustrating a method of fabricating a 2D wedge on an optical device, such as the 2D wedge of FIGS. 1B and 1C. [Figure 3A] 1 is a cross-sectional view of an optical device including an optical layer. [Figure 3B] 1 is a cross-sectional view of an optical device including an optical layer and a photoresist layer formed over the optical layer. [Figure 3C] 1 is a cross-sectional view of an optical device including an optical layer and a photoresist layer having 2D features formed therein. [Figure 4] 3D is a flowchart illustrating a method of producing a photoresist layer having the 2D features of FIG. 3C formed therein. [Figure 5A] 1 is a cross-sectional view of an optical device including an optical layer and a photoresist layer thereon. [Figure 5B] 1 is a cross-sectional view of an optical device including an optical layer and a photoresist layer with a 2D wedge formed therein. [Figure 5C] FIG. 5C is a cross-sectional view of an optical device in which the 2D wedge of FIG. 5B has been transferred to an optical layer. [Figure 5D] FIG. 1 is a cross-sectional view of an optical device including optics. [Figure 5E] FIG. 5E is a cross-sectional view of the optical device of FIG. 5D, in which the pattern of 2D wedges has been transferred to the underlying optical layer. [Figure 6A] 1 is a flow chart illustrating a method for fabricating a 2D wedge in an optical device. [Figure 6B] 1 is a flow chart illustrating a method for fabricating a 2D wedge in an optical device. [Figure 7A] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer. [Figure 7B] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer having an opening formed therethrough. [Figure 8] 7C is a flow chart illustrating a method of etching an opening in the encapsulation layer of the optical device of FIGS. 7A and 7B. [Figure 9A] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer, the optical device including a thickness anomaly formed in the membrane layer. [Figure 9B] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer with an abnormality removed. [Figure 10] 1 is a flow chart illustrating a method for correcting an anomaly on a material layer of an optical device. [Figure 11] FIG. 1 is an isometric view of an inkjet etching apparatus. [Figure 12A] 2 is a cross-sectional view of an optical device having an optical layer and an encapsulation layer formed thereon. [Figure 12B] 1 is a cross-sectional view of an optical device including an optical layer and an encapsulation layer having a 1D wedge formed therein. [Figure 12C] FIG. 12C is an isometric view of the optical device of FIG. 12B. [Figure 13] 1 is a flow chart illustrating a method of etching a 1D wedge on a material layer of an optical device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] 1A, 1B, and 1C, there are shown schematic cross-sectional side and isometric views of an optical device 10 in which a 2D wedge 11 is formed in an encapsulation layer of the optical device 10 (FIGS. 1B, 1C), the optical device 10 being useful as a waveguide for use in virtual reality imaging and other applications. The encapsulation layer 12 extends over and covers an optical layer 19, which is adapted to receive light via its in-coupler 15 and allow the light to pass through the optical layer 19 and out of the optical device via its out-coupler 16, all of which are integrally formed on a substrate 14. The optical device 10 includes a 2D wedge 11 in the encapsulation layer 12 in the region above the outcoupler 16, which here is formed using an inkjet wet etcher 1100 (FIG. 11) that dispenses an etchant to selectively and locally remove material from the encapsulation layer 12 of FIG. 1A to locally form a 2D wedge extending inward 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 contour 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 the relatively thick encapsulation layer 12 is present to cover the optical layer 19 and create a condition 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 in or as part of the portion of the encapsulation layer 12 above the outcoupler 16, the transmission and refractive characteristics of the device are modified.

[0007] To form the 2D wedge 11, as shown in Figure 1A, an optical device 10 having an encapsulation layer 12 of uniform thickness over an optical layer 19 supported on its substrate 14 is mounted on a movable stage 1114 of an inkjet etcher 1100 of Figure 11. As shown in Figure 11, the inkjet etcher 1100 includes a table 1102 supported on its base 1112 and 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 having an outlet nozzle 1108a-d configured to dispense droplets 1106 of liquid material therefrom and terminating in a droplet dispensing opening 1110a-1104d facing towards the table 1102. Stage 1114 is rotatably coupled to table 1102, for example via a shaft (not shown) connected to a stepper or servo motor (not shown) in table 1102, thereby enabling stage 1114 to rotate about its center 1116 in the θ direction in FIG. 11. To wet etch or remove individual portions of the encapsulation layer 12 to form 2D wedges 11 in desired areas of the outer surface of the encapsulation layer 12, here on the outcoupler 16 of the device 10, a stage 1114 is positioned under the droplet dispensing opening 1110 of the outlet nozzle 1108 of an inkjet dispenser 1104 of the inkjet etcher 1100, where the encapsulation layer 12 faces towards the outlet nozzle 1108 of the inkjet etcher, 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 nozzle is located away from the droplet dispensing opening 1010 of the outlet nozzle 1008 by a distance greater than the thickness of the optical device 10, 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, approximately 2 mm to 5 mm.

[0008] Here, the optical device 10 including the optical layer 19 and with the in-coupler 15 and out-coupler 16 encapsulated by the encapsulation layer 12 is placed on a stage 1114, where one or more droplet dispensing openings 1110 of an inkjet device 1104 dispense droplets 1106 of a wet etching or reactive chemical onto the encapsulation layer 12 to form a 2D wedge 11 feature by etching a concave, generally conical recess or wedge contour 11a, said recess or wedge contour 11a forming the conical outer surface of the 2D wedge 11. Said wedge contour 11a forming the outer surface of the 2D wedge 11 is provided by etching more where the deepest point of the wedge contour 11a is to be formed, etching less on the side of the 2D wedge 11 or where the wedge contour 11a is in the shape of a cone surface, and etching less along said side portion radially outward from the deepest point of the wedge contour 11a to the edge of the wedge contour 11a. Examples of possible layer materials of the encapsulation layer 12 in which the 2D wedge contour 11a is formed and their suitable paired etchants include the following pairs: SiO2 material with DHF etchant, Si3N4 material with HF or H3PO4 etchant, TiO2 material with SC1 etchant, carbon-based material with organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using KOH etchant. Etching the 2D wedge contour 11a to form the 2D wedge 11 in a membrane layer such as the encapsulation layer 12 can be done in a variety of different ways.

[0009] In one approach or embodiment of forming the 2D wedge 11, droplets 1106 of etchant, each having the same or nearly the same etchant concentration or molar concentration, are dropped uniformly as droplets 1106 from a jet nozzle 1108 over the area where the 2D wedge 11 is to be formed. As the etchant reacts with the underlying thin film material, and now with the encapsulation layer 12 on which it was dropped, the etchant is consumed in reaction with the thin film material. The reaction rate and consumption rate of the etchant are time-related, and the etching reaction can be altered or stopped by the addition of a quenching chemical. In one embodiment, as shown in FIG. 13, an inkjet dispenser 1104a supplying etchant to its outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. Here, a first line 1118a contains a uniform concentration or molar concentration of etchant, and a uniform concentration of quenching chemical is provided in a second line 1120a. Each of the first line 1118a and the second line 1120a contains a valve 1122a, 1124a that can be selectively opened to adjust or vary the flows through the valves 1122a, 1124a, i.e., the flows of etchant (first line 1118a, valve 1122a) and quenching chemical (line 1120a, valve 1124a) into and through the droplet dispensing opening 1110a of the outlet nozzle 1108a. The quenching chemical reacts preferentially with the etchant over the etchant's reaction with the encapsulation material 12, so that the etchant is consumed by the quenching chemical and etching of the encapsulation layer 12 stops.

[0010] To create the 2D wedge 11, i.e., to etch the conical wedge contour 11a of Figures 1B and 1C using the present inkjet printer 1100, an etchant is discharged through a first line 1118a to an outlet nozzle 1108a to cover the entire area where the wedge contour 11a is to be formed, and immediately thereafter, a quenching chemical is discharged around the area where the wedge contour 11a is being formed. The areas inside the periphery of the wedge 11 being formed where the wedge contour 11a is gradually deeper will receive the quenching chemical at gradually slower times and in separate time intervals between the dispensing of the quenching chemical, such that the deepest point of the forming wedge 11 is the last to receive the quenching chemical. The locations of the encapsulation layer 12 inside the periphery of the wedge contour 11a being formed receive the quenching chemical by moving the stage 1114 to position the individual areas of the encapsulation layer 12 under the stream 1106 of droplets of the quenching chemical at a predetermined time when the wedge 11 has a desired remaining encapsulation layer 12 thickness at that location. Once the entire surface of the wedge contour 11a of the encapsulation layer 12 has been quenched, i.e., after the conical wedge contour 11a is formed inwardly on the surface of the encapsulation layer 12, the encapsulation layer 12 is rinsed with deionized water dispensed by the rinse nozzle 1126 of FIG. 11 to remove the etched debris, any residual etchant, quenching chemical, and any by-products formed thereon. The optical device 10 with the formed wedge is then 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.Further, to reduce processing time for etching the wedge contour 11a, two or more of the inkjet dispensers 1104a-c may be used to dispense one or both of the etchant and the quenching chemical, or at least two of the inkjet dispensers 1104a-d may be used to dispense the etchant and one or more different inkjet dispensers of the inkjet dispensers 1104a-d may be used to dispense the quenching chemical.

[0011] In a second embodiment, the etchant is dispensed over the wedging region with varying times or amounts. As the dispensed etchant reacts with the underlying material, the etchant is consumed. To achieve deeper etching of the encapsulation layer 12, more droplets 1106 (increased droplet density) are discharged in the deeper etching region and fewer droplets 1106 (lower droplet density) are discharged in the shallower region of the wedge region to be formed at the same time or while the etchant is depleted or consumed in the region to form the deeper part of the wedge contour 11a compared to the region to be formed shallower. In this embodiment, the droplets dispensed by the inkjet dispenser 1104 have a uniform etchant concentration. The etchant reacts at the location of contact with the encapsulation layer 12 until its own chemical reaction with the material of the encapsulation layer 12 is exhausted, i.e., until the etchant is nearly consumed, and a limited amount of etching occurs for each droplet 1106. Thus, in areas where fewer droplets 1106 are dispensed, less etching occurs inwardly at the encapsulation layer 12 relatively simultaneously or over a period of time as the etchant is consumed, and in areas where more droplets are released, more etching occurs inwardly at the encapsulation layer 12 relatively simultaneously or over a period of time as the etchant is consumed. Preferably, the etchant is released continuously and strategically onto the surface of the encapsulation layer 12 at a rate no faster than its rate of consumption by reaction with the encapsulation layer material 12, using X-direction and θ (rotational) motions of the stage 1114 to deposit the droplets 1106 at locations where the wedge profile 11a is to be formed, where the stage 1114 moves the encapsulation layer 12 under the stream of droplets 1106 to selectively replenish the etchant at discrete locations on the encapsulation layer 12. The area of ​​the encapsulation layer 12 that receives the etchant droplets 1106 decreases in a stepwise or continuous manner around the deepest point of the wedge contour 11a formed inwardly into the encapsulation layer 12 as the etchant is consumed by reaction with the encapsulation layer, such that the etchant is not dispensed into areas of the already formed wedge contour 11a that are shallower than a certain depth, i.e., areas that have already been etched to the final depth of the wedge contour 11a.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 in which the wedge contour 11a defining the outer surface of the wedge 11 is to be formed, then the area centered on the deepest point of the wedge contour 11a becomes progressively smaller, and the stage finally stops to position the deepest point of the wedge contour 11a to be formed under the last of the droplets 1106 being ejected from the droplet dispensing opening 1110 of the output nozzle 1108, completing the etching of the encapsulation layer 12 to form the wedge contour 11a and thus the wedge 11 in the encapsulation layer 12. In this manner, the portions of the encapsulation layer 12 where the shallower sides of the wedge contour 11a are formed receive fewer droplets 1106 of the etchant and are etched by the fewer droplets 1106, while the portions of the deepest regions of the wedge contour 11a that are etched into the encapsulation layer 12 receive the most droplets 1106, where the encapsulation layer 12 is recessed inwardly the deepest. The surface of the encapsulation layer 12, including the outer surface of the just-formed wedge 11, is then washed with deionized water dispensed by a washing nozzle 1126 to remove the etched debris, the etchant, the quenching chemicals, and any by-products formed therein. The optical device 10 is then removed from the support 1114 and placed in a washing and drying station 1128. As in the first embodiment of forming the wedge contour 11a, multiple inkjet dispensers from the inkjet dispensers 1104a-b can be used to dispense droplets, potentially reducing the time required to etch the wedge contour 11a.

[0012] In a third embodiment, the etchant for forming the wedge contour 11a is released in varying concentrations or molarities over the area where the wedge contour 11a is to be formed, defining the wedge 11 of the encapsulation layer 12. As the etchant reacts with the underlying material of the encapsulation layer 12, the etchant is consumed. To achieve a deeper etch in the desired area of ​​the encapsulation layer 12, droplets 1106 with a higher etchant concentration or molar concentration are released in the area to be etched deeper, and droplets with a lower concentration (diluted droplets) are released in the area to be etched smaller, i.e., in the shallower area of ​​the wedge contour 11a. To achieve this, in one embodiment, a dispenser 1104 supplying etchant to an outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. A first line 1118a contains a uniform concentration or molar concentration of etchant, and a diluent, e.g., deionized water, is provided in a second line 1120a. Each of the first line 1118a and the second line 1120a contains a valve 1122a, 1124a that can be selectively opened to adjust or change the flows through the valves 1122a, 1124a, i.e., the flow of etchant (line 1118a, valve 1122a) and the flow of diluent (line 1120a, valve 1124a) into and through the outlet nozzle 1108a. The relative flows of the diluent and etchant result in different concentrations of etchant per droplet 1106 dispensed from the droplet dispensing opening 1110a. The dispensed etchant 1116 reacts where it contacts the encapsulation layer 12 until the chemical reaction is exhausted, resulting in a limited amount of etching per droplet, with less etching occurring where droplets 1106 with lower etchant concentrations are dispensed. The etchant droplets 1106 are continuously released at a rate no faster than they are consumed by their own reaction with the encapsulation layer material 12, whereupon the stage 1114 moves to pass under the inkjet stream 1106 a wedge contour 11a that defines the area of ​​the optical device 10.The portion of the area where the wedge contour 11a is to be formed, where the etchant is dispensed thereon, extends over the entire area where the wedge contour 11a is to be formed, where the droplet dispensing opening 1110a of the outlet nozzle 1108a ejects droplets 1106 with a greater increase in the ratio of etchant to diluent from locations around the periphery of the area of ​​the encapsulation layer 12 to be etched to locations on the encapsulation layer 12 where the deepest etching into the encapsulation layer 12 to form the wedge contour 11a occurs, where the diluent is not ejected with the etchant. Thus, the less deep side of the wedge contour 11a receives the less concentrated etchant droplets, and the deepest area 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 depth. The surfaces of the encapsulation layer 12 and the formed wedge 11 are then washed with deionized water dispensed by a rinse nozzle 1126 to remove etched debris, etchant, quenching chemicals, and any by-products formed therein. The optical device 10 is then removed from the support 1114 and placed in a cleaning and drying station 1128. As in the first and second embodiments, multiple inkjet dispensers 1104a-b can be used to dispense droplets of different concentrations, thereby potentially reducing the time required to etch the wedge contour 11a. Additionally, one or more of the inkjet dispensers 1104a-d can be supplied with an etchant containing different concentrations of etchant, where droplets 1106 with lower concentration are dispensed in areas of the surface of the encapsulation layer 12 where the variable depth openings should be shallower, and etchants with higher concentration are dispensed in areas of the surface of the encapsulation layer 12 where the variable depth openings should be deeper. In this approach, one of the inkjet dispensers 104a-d can dispense a diluent which is then mixed with different concentrations of etchant in different regions of the encapsulation layer, resulting in a continuous or near-continuous change in etchant concentration in the liquid across the encapsulation layer from the deepest to the shallowest portions of the wedge profile 11a being formed.

[0013] In a fourth embodiment, the etchant is released in droplets 1106 of various sizes over the area of ​​the encapsulation layer where the wedge contour 11a is to be formed to form the wedge 11. As the etchant reacts with the underlying material of the encapsulation layer 12, the etchant is consumed. To achieve a deeper etch into the encapsulation layer, larger droplets 1106 are released in the deeper etch areas and smaller droplets 1106 are released in the shallower wedge contour 11a areas. To achieve this, the inkjet printer 1100 includes an inkjet dispenser 1104 that can dispense smaller or larger droplets that fall as droplets 1106 through a droplet dispensing opening 1110 of an outlet nozzle 1108. The etchant reacts where it contacts the encapsulation layer 12 until the chemical reaction is exhausted, resulting in a limited amount of etching per droplet, with less etching occurring where smaller etchant droplets 1106 were dispensed. Here, the viscosity of the droplets is increased to prevent them from moving too far from their placement on the encapsulation layer 12. The etchant droplets 1106 are sequentially released over the entire area of ​​the encapsulation layer 12 where the wedge contour 11a for forming the wedge 11 should be formed at a rate not faster than the consumption rate of the etchant by its own reaction with the encapsulation layer material 12, where the stage 1114 moves under the flow of the droplets 1106 various parts of the wedge contour 11a to be formed to various depths of the encapsulation layer 12 and thus the optical device 10. The size of the droplets 1106 gradually increases from the periphery of the wedge contour 11a to be formed to the position where it is to be etched deepest. In this way, the shallower side areas of the wedge contour 11a being formed receive smaller etchant droplets 1106, and the deepest areas of the wedge contour 11a being formed receive the largest droplets, so that at that position the encapsulation layer 12 is etched deepest. The surface of the encapsulation layer 12 on which the wedge 11 is formed is then washed with deionized water dispensed by the washing nozzle 1126 to remove the etched debris, etchants, quenching chemicals and any by-products formed thereon.The optical device 10 is then removed from the support 1114 and placed into a cleaning and drying station 1128 .

[0014] As with the first to third aspects of forming the wedge 11, multiple jet dispensers among the inkjet dispensers 1104a-1104b can be used to eject droplets of various sizes, or each of the inkjet dispensers 1104a-1104d is configured to provide droplets within various subranges of sizes, thereby reducing the time required to etch the wedge contour 11a.

[0015] Figure 2 is a flow chart showing a sequence of operations for fabricating a 2D wedge 11 in the encapsulation layer 12 of the optical device 10, according to the sequence of processes described with respect to Figure 1. First, the optical layer 19 is prepared. However, the encapsulation layer 12 may need to vary in thickness to produce the desired effect for the optical device 10, and thus the formation of the 2D wedge 11 may take place. A processing sequence for forming the 2D wedge in the encapsulation layer 12 will now be described.

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

[0017] In one embodiment, after the etchant is discharged through line 1118a into outlet nozzle 1108a to cover the entire area where wedge contour 11a for forming wedge 11 is to be formed, quenching chemical is immediately thereafter discharged around the area where wedge contour 11a is to be formed in operation 211. Locations of encapsulation layer 12 inside the periphery of wedge contour 11a being formed receive quenching chemical by movement of stage 1114 to position individual areas of encapsulation layer 12 under the flow of quenching chemical droplets 1106 at a predetermined time when wedge contour 11a has had enough material removed to form the desired encapsulation layer 12 thickness of wedge 11 at that location, and then the formed wedge contour 11a becomes deeper and deeper. Once the entire surface of the wedge contour 11a of the encapsulation layer 12 has been quenched, in operation 221, the surface is rinsed with deionized water dispensed by a rinse nozzle 1126 to remove the etched debris, any residual etchant, quenching chemicals, and any by-products formed thereon. Then, in operation 231, the optical device 10 with the wedge 11 formed thereon is removed from the stage 1114 and, in operation 241, placed in a cleaning and drying station 1128 having a spin rinse chuck 1130 to further rinse and dry the surface of the encapsulation layer 12 with the 2D wedge formed thereon.

[0018] In a second embodiment, in operation 205, a deeper etch is achieved by dispensing more droplets (higher droplet density) in areas where the wedge contour 11a is to be formed deeper into the encapsulation layer 12, and fewer droplets (lower droplet density) are released in areas where the wedge contour 11a is to be formed shallower. Here, the inkjet dispenser 1104 drops droplets 1106 with a uniform etchant concentration to contact the area of ​​the encapsulation layer 12 where the wedge contour 11a is to be formed, with each droplet etching a limited amount, until the chemical reaction is exhausted, i.e., the etchant is nearly consumed. Thereafter, in operation 213, the movement of the stage 1114, and thus the movement of the encapsulation layer 12 under the flow of the droplets 1106, selectively replenishes the etchant at distinct locations on the encapsulation layer 12 where the wedge contour 11a is formed over time further into the encapsulation layer 12 in operation 213, thereby achieving a density change of the droplets on the surface in the area where the wedge contour 11a is formed. Alternatively, if the viscosity of the droplets 1106 is relatively high and does not move significantly from the dropped position on the encapsulation layer, a single pass of the wedge contour 11a forming the area of ​​the encapsulation layer 12 under the droplet dispensing outlet 1010 can cause more droplets 1106 to be dropped in the location where the wedge contour 11a is to be deeper than the area where it is to be shallow, such that a thicker layer of etchant is present over the deeper location of the wedge contour 11a to be formed than the area where it is to be shallower. Thereafter, in operation 223, the surface of the encapsulation layer 12 including the wedge 11 is washed with deionized water dispensed by a cleaning nozzle 1126 to remove etched debris, etchants, quenching chemicals and any by-products formed thereon. From here, in operation 233, the optical device 10 is removed from the support 1114 and, in operation 243, placed in a cleaning and drying station 1128, after which the surface of the encapsulation layer 12 with the 2D wedge formed thereon is further rinsed and dried.

[0019] In a third embodiment, in operation 205, etchant is released in droplets 1106 of different etchant concentrations at different locations of the wedge profile 11a being formed. In operation 215, droplets with higher etchant concentration or molar concentration are released in areas of the encapsulation layer 12 to be etched deeper, and droplets with lower concentration (diluted droplets) are released in areas to be etched less heavily, i.e., at shallower locations of the wedge profile 11a to be formed. Thereafter, in operation 225, the surface of the encapsulation layer 12 including the wedge 11 is rinsed with deionized water dispensed by a rinse nozzle 1126 to remove etched debris, etchant, quenching chemicals, and any by-products formed therein. From here, in operation 235, the optical device 10 is removed from the support 1114 and, in operation 245, placed in a cleaning and drying station 1128, after which the surface of the encapsulation layer 12 on which the 2D wedge is formed is further rinsed and dried.

[0020] In a fourth embodiment, as the etchant is released in operation 205, droplets of various sizes are released over the area of ​​the encapsulation layer 12 where the wedge profile 11a is to be formed. In operation 217, larger droplets are released in the deeper etching areas and smaller droplets are released in the shallower etching areas, where the droplet size is adjusted by the inkjet dispenser 1104. The shallower sides of the forming wedge profile 11a receive the smaller etchant droplets 1106, and the deepest areas of the forming wedge profile 11a receive the largest droplets, so that the encapsulation layer 12 is etched to the deepest depth at that location. Thereafter, in operation 227, the surface of the encapsulation layer 12 where the wedge 11 is formed is washed with deionized water dispensed by the washing nozzle 1126 to remove the etched debris, etchant, quenching chemicals, and any by-products formed therein. In operation 237, the optical device 10 is removed from the support 1114 and, in operation 247, placed in a cleaning and drying station 1128 whereupon the surface of the encapsulation layer 12 on which the 2D wedge is formed is further rinsed and dried.

[0021] 3A-3C, an additional method for forming a photoresist layer to form a wedge profile as in the optical layer of FIG. 5E is shown, in which an inkjet printer 1100 is used to deposit individual droplets 1106 of photoresist material to form a photoresist layer 30 on an underlying thin film layer 19c on a substrate 21, where the formed photoresist layer 30 includes a composition that varies over its length such that individual non-uniform portions 23 are formed in the photoresist layer 30, 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. The three-dimensional profile of the three-dimensional recess in the photoresist 30 is then transferred by anisotropic etching, such as in a plasma etch chamber, to the underlying thin film layer 19c to form a structure similar to the 2D wedge of FIG. 5E.

[0022] The photoresist material for forming the photoresist layer 30 is dispensed in liquid form and then baked to harden, for example, by including a heater (not shown) below and thermally connected to the stage 1114 of the inkjet device 1100, where the composition of the photoresist layer 30 is altered in the non-uniform region 23 compared to the remaining portions of the photoresist of the photoresist layer 30 formed on the thin film layer 19c, and is used to form the three-dimensional features 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-photosensitizer additive components of the photoresist material dispensed as droplets 1106 by inkjet device 1100 may be maintained in a uniform state across the length, width, and depth of the photoresist layer formed on thin film layer 19c, but the photosensitizer portions of the photoresist that cause the polymer of the photoresist material to change properties when exposed to appropriate electromagnetic energy, such as UV light, are contained non-uniformly within photoresist layer 30, i.e., between non-uniform regions 23 and the remainder of photoresist layer 30, and also within non-uniform regions 23 of photoresist layer 30.

[0023] To form the non-uniform regions, a first line 1118a of the inkjet dispenser 1104a is configured to deliver the polymer, solvent and non-photosensitive additive components of the photoresist material, and a second line 1120a of the inkjet dispenser 1104a is configured to deliver 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 about its axis 1116 and moves in the X direction using the movement of the table 1102 to position the entire area of ​​the upper surface of the thin film layer 19c facing the outlet droplet dispensing opening 1010 of the dispensing nozzle 1108 for receiving the polymer, solvent and non-photosensitive 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 so that the polymer, solvent, and non-photosensitizer additive components of the photoresist are simultaneously flowed onto the thin film layer 19c along with the photosensitizer.

[0024] For example, assume that three-dimensional feature 31 is circular in plan view, extends from edge 31a to its deepest point 31b, has a conical profile similar to wedge profile 11a and 2D wedge 11 shown in Figures 1B and 1C, and has a smooth depth transition from edge 31a to deepest point 31b. When the surface of thin film layer 19c directly below droplet dispensing opening 1110 is an area where three-dimensional feature 31 is not to be formed, only polymer, solvent, and non-photosensitizer additive components of the photoresist are dispensed as droplets 1106. While the substrate 21 is positioned under the droplet dispensing opening 1110 of the outlet nozzle 1108, the substrate 19c is moved to a first position, i.e., directly below the droplet dispensing opening 1110, to the position of the end 31a of the three-dimensional feature 31 to be formed, and a photosensitizer is added to the polymer, solvent, and non-photosensitizer additive components of the photoresist material being dispensed as droplets 1106 from the droplet dispensing opening 1110. While the stage 1014 moves the substrate 21 to position the deepest portion 31b of the three-dimensional feature 31 to be formed under the droplet dispensing outlet 1110, more sensitizer is continuously added to the polymer, solvent, and non-photosensitive additive components of the photoresist material being dispensed as droplets 1106 through the droplet dispensing opening 1110a, such that the sensitizer in the mixture of polymer, solvent, and non-photosensitive additive of the photoresist being dispensed and the sensitizer has a maximum concentration at the deepest position of the three-dimensional recess 1214 to be formed, and the concentration gradually decreases, here approximately linearly, as the stage 1114 traverses the position of the thin film layer under the opening 1110 from the deepest portion 31b of the three-dimensional feature 31 to be formed to its shallowest position (occurring at the end 31a). The resulting photoresist layer 30, which is sensitive to electromagnetic energy only in the areas where the photosensitive agent is present, can be formed over the entire surface of the thin film layer 19c in a single pass under the outlet nozzle 1108, or multiple layers of polymer, solvent and non-photosensitive agent additive components of the photoresist can be formed where a gradient of photosensitive agent can be dispensed at appropriate locations (where three-dimensional features are to be formed) to form the photoresist layer 30.Here, for example, while moving the substrate 21 from the deepest portion 31d of the non-uniform region 23 of the photoresist layer 30 being formed toward its shallower peripheral portion 31a, the sensitizer is initially added only at the deepest portion 31d. Thus, in successive passes forming the non-uniform region 23 of the photoresist layer 30, the area extending from the deepest portion 31d to the edge 31a increases successively, and finally, in the last pass of the dispensed droplet 1106, the sensitizer is dispensed over the entire region where the non-uniform portion 23 is formed. In addition, the photoresist layer 30 can be formed by flowing only the polymer, solvent, and non-sensitizer-additive components of the photoresist through the inkjet dispenser 1104a, and the sensitizer is flowed through the adjacent inkjet dispenser 1104b. As a result, a photoresist layer is formed having localized electromagnetic energy sensitive regions, which have a gradient of sensitivity to electromagnetic energy that causes a change in the structure of the photoresist layer.

[0025] After the photoresist layer 30 having the variable concentration photosensitive agent regions formed to form the non-uniform regions 23 is exposed to electromagnetic radiation to which the polymer and photosensitive agent combination is sensitive, the material properties of the variable concentration photosensitive agent regions are altered, so that more polymer in the deepest to-be-formed regions of the non-uniform regions 23 change properties and become more susceptible to etching, with the etch enhancement dropping to relatively zero at the edges 31a of the resulting three-dimensional features 31. The substrate 23 with the exposed photoresist layer is then exposed to a developer to dissolve and wash away the reacted polymer, creating the three-dimensional features 31 in the photoresist 30 structure of FIG. 12C.

[0026] Alternatively, if the photosensitive agent renders the polymer more resistant to dissolution by the developer when exposed to electromagnetic energy, the sequence described above is reversed, and areas of the photoresist being formed where no three-dimensional feature 31 will be present receive the photosensitive agent, and the amount of photosensitive agent decreases as the end 31a of the three-dimensional feature 31 being formed comes under the droplet dispensing opening 1110, resulting in less photosensitive agent closer to the deepest portion 31b of the three-dimensional feature 31 being formed, and at the location of the deepest portion 31 of the three-dimensional feature 31 being formed, the photosensitive agent has a minimum concentration of just zero.

[0027] 4, a processing sequence for forming a three-dimensional feature 31 is shown in process flow format. Initially, in operation 400, a substrate 23 having a thin film layer 19c, which may be, for example, an encapsulation layer 12 formed on an optical layer 19 as shown in FIG. 1, is mounted on a stage 1114 of an inkjet printer 1100. Next, in operation 402, the stage is moved to position the thin film layer 19c under a droplet dispensing opening 1110 of an inkjet dispenser 1104. Next, in operation 404, while the stage is being moved in the X and θ directions, droplets of a photoresist composition are ejected from the droplet dispensing opening 1110 onto the thin film layer 19c, such that a gradient of photosensitive agent exists in the area of ​​the photoresist layer 30 where the recessed feature is formed. After the entire thickness of the photoresist layer is deposited and baked, in operation 406, the photoresist is exposed to electromagnetic radiation, with or without a photosensitizer, that can alter the material properties of the polymer in the photoresist, and in operation 408, the exposed photoresist layer 30 is developed. Then, in operation 410, the developed photoresist layer 30 is rinsed with a solvent that dissolves the polymer and the photoresist with or without the photosensitizer, forming three-dimensional features 31 inwardly in the layer of photoresist 30.

[0028] 5A-5C, there are shown schematic side views of the results of a series of processing operations used to fabricate an optical device 10 including inwardly extending recesses 50a in the optical layer 19 of the optical device 10, useful as waveguides for use in virtual reality imaging and other applications. In contrast to the method of forming features 31 of FIGS. 3 and 4, in which a photoresist layer 30 is formed that integrally includes regions with variable photoresist material properties, here the entire thickness of the photoresist layer 30 is formed over 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 to transfer the recesses or recesses 50a in the photoresist layer to the underlying optical layer 19 in one strategy, as seen in FIGS. 5A-5C, and to form the recesses or recesses 50b directly in the optical layer 19 by localized inkjet etching without the need for a photoresist layer, as seen in FIGS. 5D and 5E. A relatively thick photoresist layer 30 can be used to cover the optical layer 19 of FIG. 5A to create conditions that allow the photoresist wedge 50 shown in FIG. 5B to be created by forming an inward recess 50a in the photoresist 30 of FIG. 5A, whereby the photoresist layer 30 of FIG. 5B is used as a mask to etch the optical layer 19 and to transfer the wedge 50 of FIG. 5B to the optical layer 19 of FIG. 5C as a transferred optical layer wedge 50c.

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

[0030] Here, the optical device 10 covered with the photoresist layer 30 is placed on a stage 1114, and a 2D photoresist wedge 50 is formed in the existing photoresist layer 30 of FIG. 5A by dispensing droplets 1106 of a wet etching or reactive chemical onto the photoresist layer 30 from one or more outlets 1108 of an inkjet dispenser 1104, etching a recess 50a inwardly into the outer surface of the photoresist layer 30, with the resulting recess 50a being shown in FIG. 5B. The recess profile is provided by causing a larger etch where the deepest point of the recess 50a is to be formed, and causing a progressively smaller etch in the side extending from the deepest point of the recess 50a to be formed, or in the annular region, i.e., where the side portions extend radially outward from the deepest portion of the recess 50a to be formed. Examples of materials for the photoresist layer 30 and their appropriately paired etchants include carbon-based materials and organic solvents or photoresist removal etchants. Etching the recesses 50a in the photoresist layer 30 can be done in a variety of different ways.

[0031] In one approach or embodiment of forming the recesses 50a, an etchant with the same etchant concentration or molar concentration is dispensed as droplets 1106 from a jet nozzle 1108 uniformly over the area where the recesses 50a for forming the photoresist wedge 50 are to be formed. As the etchant reacts with the underlying thin film material onto which it is dispensed, it is consumed in reaction with the photoresist 30. The reaction rate and consumption rate of the etchant are a function of time, and the total amount of photoresist locally etched away can be modified by the addition of a quenching chemical. In one embodiment, as shown in FIG. 13, an inkjet dispenser 1104a that supplies an etchant to an outlet nozzle 1108a is connected to two different supply lines 1118a and 1120a. The first line 1118a contains a uniform concentration or molar concentration of the etchant, and a uniform concentration of a quenching chemical is provided in the second line 1120a. The first line 1118a and the second line 1120a each include a valve 1122a, 1124a that can be selectively opened to adjust or vary the flows through the valves 1122a, 1124a, i.e., the flow of etchant (line 1118a, valve 1122a) and the flow of quenching chemical (line 1120a, valve 1124a) 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 etching of the photoresist layer 30 is stopped.

[0032] To create a photoresist wedge 50 using the system, an etchant is discharged through line 1118a to outlet nozzle 1108a to cover the entire area where the photoresist wedge 50 is to be formed, followed immediately by a quenching chemical being discharged to a location on the periphery of the recess 50a being formed. Progressively deeper areas of the recess 50 being formed that are located inside the periphery of the recess 50 to be formed will receive the quenching chemical at progressively later times and at discrete time intervals between the dispensing of the quenching chemical, until the deepest point of the recess 50a being formed receives the quenching chemical. The locations of the photoresist layer 30 inside the perimeter of the recess 50a being formed receive the quenching chemical at a predetermined time based on the desired thickness of the recess 50a at that location by movement of the stage 1114 to position the individual areas of the photoresist layer 30 under the flow of droplets of quenching chemical 1106, thereby leaving the desired thickness of the photoresist layer 30 to provide the photoresist wedge 50. Once the entire surface of the recess 50a of the photoresist layer 30 has been quenched, the photoresist surface 50 is rinsed with a neutral liquid, such as deionized water, dispensed by a rinse nozzle 1126 to remove the etched debris, any residual etchant, the quenching chemical, and any by-products formed therein. The optical device 10 with the photoresist wedge 50 formed thereon is then removed from the stage 1114 and placed in a rinse and dry station 1128 having a spin rinse chuck 1130 for further rinsing and drying.

[0033] In a second embodiment of making the photoresist wedge 50, an etchant is dispensed in a time-varying manner over the area where the recess 50a is to be formed. As the dispensed etchant reacts with the underlying material, the etchant is consumed. To achieve a deeper etching of the photoresist layer 30 in the selected portion of the photoresist layer 30, more droplets 1106 (increased droplet density) are released in the deeper etching area and fewer droplets (lower droplet density) are released in the shallower area where the recess 50a is to be formed. In this embodiment, the droplets 1106 of the inkjet dispenser 1104 have a uniform etchant concentration. The etchant reacts with the photoresist where it contacts the photoresist layer 30 until the chemical reaction is exhausted, i.e., the etchant is nearly consumed, and a limited amount of etching is performed per droplet. Thus, in areas where fewer droplets are released, less etching is done inwardly into the photoresist layer 30, and in areas where more droplets are released, more etching is done inwardly into the photoresist layer 30. The etchant is released in a sequential, planned manner at a rate no faster than it is consumed by its reaction with the photoresist layer 30, where stage 1114 moves the photoresist layer 30 under the stream of droplets 1106 to selectively replenish the etchant at desired locations on the photoresist layer 30. In areas where the photoresist 30 forms a deeper depression 50a, more droplets 1106 are dispensed, and in areas where the photoresist 30 forms a shallower depression 50a, fewer droplets are dispensed, where the greatest number of droplets 1106 are dispensed up over the areas where the depression 50a is deepest, and the fewest droplets are dispensed around the depression 50a where the depression is shallowest.The stage 1114 first moves the photoresist layer 30 under the outlet nozzle 1108 to cover the entire area where the depression 50a and thus the wedge 50 are to be formed, with smaller and smaller areas centered on the deepest point of the depression 50a to be formed receiving the etchant, and the stage finally stops to position the droplet dispensing outlet 1110 over the deepest point of the depression 50a to be formed where additional droplets 1106 of etchant are dispensed to complete the etching of the photoresist layer 30 to form the wedge 50. By this method, the portions of the photoresist layer 30 where the shallower sides of the wedge 50 depression 50a are formed receive and are etched by the fewer droplets 1106 of etchant, and the deepest areas of the depression 50a formed inwardly in the photoresist layer 30 receive the most droplets 1106, where the photoresist layer 30 is recessed to the deepest depth. The surface of the photoresist layer 30, including the wedge 50, is then washed with deionized water dispensed by a washing nozzle 1126 to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. The optical device 10 is then removed from the support 1114 and placed in a washing and drying station 1128 for further washing and drying.

[0034] In a third embodiment, an etchant is released in a variable concentration or molarity over the area where the wedge 50 and thus the recess 50a are 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 in the desired area of ​​the photoresist layer 30, droplets 1106 with a higher etchant concentration or molarity are released in the area to be etched deeper, and droplets with a lower concentration (diluted droplets) are released in the area to be etched smaller, i.e., in 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, e.g., deionized water, is supplied in the second line 1120a. The first line 1118a and the second line 1120a each include a valve 1122a, 1124a that can be selectively opened to adjust or change the variable flows through the valves 1122a, 1124a, i.e., the flow of etchant (line 1118a, valve 1122a) and the flow of diluent chemical (line 1120a, valve 1124a) into and through the droplet dispensing opening 1110a of the outlet nozzle 1108a. The relative flows of diluent and etchant result in different concentrations of etchant per droplet 1006. The dispensed etchant 1116 reacts where it contacts the photoresist layer 30 until the chemical reaction is exhausted, resulting in a limited amount of etching per droplet, with less etching occurring where droplets 1006 with lower etchant concentrations are dispensed. The etchant is released in a sequential, planned manner at a rate no faster than the rate at which it is consumed by the material 12 of the photoresist layer 30 , where the stage 1114 moves the optical device 10 under the stream of droplets 1106 .The area where the etchant is dispensed extends over the entire area where the photoresist wedge 50 and thus the recess 50 are to be formed, where the droplet dispensing outlet 1110 of the outlet nozzle 1108a releases droplets 1106 with an increased ratio of etchant to diluent from a location at the periphery of the area of ​​the photoresist layer 30 to be etched to a location on the photoresist layer 30 where the deepest etching into the photoresist layer 30 occurs, where no diluent is released along with the etchant. Thus, the shallower sides of the recess 50a receive the less concentrated etchant droplets 1106, and the deepest area of ​​the recess 50a to be formed in the photoresist layer 30 where the photoresist wedge 50 is formed receives the most concentrated droplets 1106 and is therefore etched to the deepest depth. The surface is then washed with deionized water dispensed by the rinse nozzle 1126 to remove the etched debris, the etchant, the quenching chemicals and any by-products formed therein. The optical device 10 is then removed from the support 1114 and placed in a cleaning and drying station 1128 where it is cleaned and dried.

[0035] In a fourth embodiment, an etchant is released in droplets of various sizes over the area 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 released in the deeper etch areas and smaller droplets are released in the shallower wedge areas. To achieve this, the inkjet printer 1100 includes an inkjet dispenser 1104 that can dispense smaller or larger droplets that fall as droplets 1106 through a droplet dispensing outlet 1010 of an outlet nozzle 1108. The etchant reacts where it contacts the photoresist layer 30 until the chemical reaction is exhausted, resulting in a limited amount of etching per droplet, with less etching occurring where smaller etchant droplets 1106 were dispensed. Here, a more viscous material or medium of the etchant is preferably used to reduce the flow of the etchant from the location on the photoresist where it is dispensed, so that a thicker layer of etchant can be present on the deepest part of the depression to be formed, which tapers in thickness to the thinnest part of the etchant present at the periphery of the depression 50a to be formed. The size of the droplets 1106 gradually increases from the periphery of the depression 50a to be formed to the location to be etched deepest. Thus, the shallower side of the area where the depression 50a is formed receives the smaller etchant droplets 1106, and the deepest area of ​​the depression 50a to be formed receives the largest droplets, and thus the photoresist layer 30 is etched deepest at that location. The surface of the photoresist layer 30 on which the wedge 50 is formed is then washed with deionized water dispensed by a cleaning nozzle 1126 to remove the etched debris, etchants, quenching chemicals, and any by-products formed therein. The optical device 10 is then removed from the support 1114 and placed in a cleaning and drying station 1128 to be cleaned and dried.

[0036] As a result, an optical device 10 having a flat optical layer 19 including a photoresist layer 30 provided with 2D wedges 50c can be used to form 2D wedges 50c in the optical layer 19 as shown in FIG. 5C. The photoresist layer 30 is used as a masking pattern for anisotropic plasma etching of the device, and the outline of the wedges 50 is transferred to the optical layer as optical layer wedges 50b, as shown in FIG. 5C. This reactive ion etch removes both the photoresist layer 30 and the material of the optical layer 19, and etches the pattern of wedges 50c into the optical layer 19 as shown in FIG. 5C. The thickness variation caused by the 2D wedges 50 in the photoresist 30 allows a larger etch of the optical layer 19 under where the photoresist 30 is thinner, i.e., in the deeper regions of the recesses 50a, and a smaller etch in the optical layer under the thicker covered areas of the photoresist 30, i.e., in the shallower regions of the recesses 50a and in the non-recessed areas of the photoresist 30. The resulting etch transfers the pattern of the photoresist wedges 50 into the optical layer 19, resulting in an optical device 10 that includes 2D optical layer wedges 50c in the optical layer 19. The remaining photoresist layer 30 is then etched away, and the resulting device is cleaned, such as by a wet cleaning process.

[0037] 5D and 5E, schematic side views of an optical device 10 are shown to illustrate different sequences of operations for fabricating the device 10, including a 2D optical layer wedge 50b within the optical layer 19 of the optical device 10. The optical device 10 does not have a photoresist layer 30. In this embodiment for forming the optical layer wedge 50b in the optical layer 19, all four embodiments of the process for forming 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] 6A is a flow chart illustrating a sequence of operations for fabricating a 2D optical layer wedge 50b in the optical layer 19 of the optical device 10, according to the sequence of processes described with respect to FIGS. 5A-5C. First, the optical layer 19 is prepared, coated with a photoresist layer 30 by flowable chemical vapor deposition, physical vapor deposition, spin coating, or other deposition framework, and 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 comprised of an optical layer 19 including a photoresist layer 30 is placed or mounted on a stage 1114 in an inkjet wet etching apparatus 1100, and the stage moved in the X and θ directions in FIG. 11 positions a desired location on the photoresist 30 where a wedge 50 is to be formed under a droplet dispensing opening 1010 of an outlet 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, the etchant has an etch rate of the material of the optical layer 19 that is about 100 times or more less than the etch 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 a stage 1114 and droplets 1106 of a wet etching or reactive chemical are dispensed from one or more outlets 1108 of an inkjet device 1104 onto the photoresist layer 30 to form a photoresist wedge 50 defined by the surface of a depression 50a extending inwardly towards the outer surface of the photoresist layer 30. The contour of the wedge or depression 50a is established by causing a larger etch where the deepest point of the depression 50a is to be formed and causing progressively smaller etches on the sides of the depression 50 or in an annular region extending radially outward from the deepest point of the depression 50a.

[0041] In one approach or embodiment, in operation 605, an etchant with the same etchant concentration or molar concentration is uniformly dispensed by droplets 1106 from a spray nozzle 1108 over the entire area where the wedge 50 is to be formed, immediately followed by a quenching chemical being dispensed around the area where the wedge is to be formed, in operation 611, and then sequentially dispensed on additional areas of the surface of the photoresist 30, until the quenching chemical is dispensed over the deepest portion of the recess 50a to be formed. After the surface of the photoresist layer 30 receives the quenching chemical and the etching reaction is quenched, in operation 621, the surface of the photoresist 30 is washed with a neutral solution, such as deionized water, to remove the etched debris, any remaining etchant, quenching chemical, and any by-products formed therein. 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 in the cleaning and drying station 1128, where the surface of the photoresist layer on which the 2D wedge 50c is formed is further rinsed and then dried.

[0042] In a second embodiment, the contour of the recess 50a is achieved by dispensing more droplets 1106 (increased droplet density) in areas of the photoresist layer 30 in areas to be etched deeper until the chemical reaction is exhausted, while fewer droplets 1106 (decreased droplet density) having a uniform etchant concentration are released and contacted on the photoresist layer 30, where areas with fewer droplets will result in less inward etching of the photoresist layer 30 and areas where more droplets are released will result in more inward etching of the photoresist layer 30, and positioning of the droplets 1106 is achieved by moving the stage 1114, and thus the photoresist layer 30, below the stream of droplets 1106 to selectively replenish the etchant at discrete locations on the photoresist layer 30. Once the recesses 50a are formed, in operation 623, the surface of the photoresist layer 30 including the wedge 50 is washed with a neutral liquid, such as deionized water, to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. The optical device 10 is then removed from the support 1114 in operation 633 and placed in a cleaning and drying station 1128 for cleaning in operation 643, after which the surface of the photoresist layer 30 with the 2D wedge 50c formed thereon is further rinsed and dried.

[0043] In a third embodiment, the etchant is released in varying concentrations or molarities over the area of ​​the photoresist layer 30 where the recess 50a is to be formed. In operation 615, droplets with a higher etchant concentration or molar concentration are released in the area of ​​the photoresist layer 30 to be etched deeper, and droplets with a lower concentration (diluted droplets) are released in the area to be etched less deeply, i.e., in the shallower wedge area. The surface of the photoresist 30 where the recess 50a is formed is then washed with a neutral liquid, such as deionized water, in operation 625. The optical device 10 is then removed from the support 1114 in operation 635 and placed in a washing and drying station 1128 for washing in operation 645, after which the surface of the photoresist layer 30 where the 2D wedge 50c is formed is further rinsed and dried.

[0044] In a fourth embodiment, the etchant is released in droplets of various sizes across the area of ​​the photoresist layer 30 where the wedge 50c is to be formed. In operation 617, larger droplets are released into the deeper etching areas of the recess 50a being formed and smaller droplets (diluted droplets) are released into the shallower areas of the recess 50a being formed to create the wedge 50c, where the size of the droplets 1106 is varied by the inkjet dispenser 1104 in the outlet nozzle 1108. Thus, the shallower sides of the area where the recess 50a is being formed receive the smaller etchant droplets 1106 and the deepest areas of the recess 50a being formed receive the largest droplets, and thus the photoresist layer 30 is etched to the deepest depth at that location. Thereafter, in operation 627, the surface of the photoresist layer 30 on which the photoresist wedge 50 is formed is washed with deionized water to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. Thereafter, in operation 637, the optical device 10 is removed from the support 1114 and, in operation 647, placed in the cleaning and drying station 1128 for cleaning, after which the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and dried.

[0045] In this manner, the resulting optical device 10 is formed having a planar upper surface of the optical layer 19 and further including the photoresist layer 30 provided with the wedges 50. At this point, in operation 650, the shape of the wedges 50c in the photoresist layer 30 is transferred into the underlying optical layer 19 by using the photoresist layer as a mask to anisotropically plasma etch portions of the optical layer to transfer corresponding wedges 50b.

[0046] Figure 6B is a flow chart illustrating a sequence of operations for fabricating a wedge 50b directly in the optical layer 19 of the optical device 10, according to the sequence of processes described with respect to Figure 1. First, the optical layer 19 of uniform thickness is prepared.

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

[0048] Here, the wedge is etched directly into the exposed surface of the optical layer 19. Examples of possible layer materials for the optical layer 19 and their suitable pairings with etchants include the following pairs: SiO2 material with DHF etchant, Si3N4 material with HF or H3PO4 as etchants, TiO2 material with SC1 etchant, carbon-based material with organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using KOH etchant. Etching the recess to form the optical layer 50b can be done in a variety of different ways.

[0049] In one approach or embodiment, after a substrate is provided and attached to a stage 1114 in operation 601, an area where a 2D wedge 50b is to be formed is positioned under a droplet dispensing outlet 1110 of an outlet nozzle 1108 of an inkjet dispenser 1104 in operation 663, and an etchant having the same etchant concentration or molar concentration is uniformly dispensed by droplets 1106 from the ejection nozzle 1108 over the area where a recess forming the optical layer wedge 50b is to be formed in operation 605. In operation 665, an etchant is ejected through a first line 1118a to the outlet nozzle 1108a to cover the entire area where the optical layer wedge 50 is to be formed, immediately followed by ejecting a quenching chemical around the area where the optical layer wedge 50b is formed in operation 671. The location of the optical layer 19 inside the perimeter of the optical layer wedge 50b being formed receives the quenching chemical by moving the stage 1114 to place the individual area of ​​the optical layer 19 under a stream of droplets 1106 of the quenching chemical at a predetermined time when the optical layer wedge 50b has the desired optical layer 19 thickness at that location. Once the entire surface of the area of ​​the optical layer 19 where the optical layer wedge 50b is being formed has been quenched, in operation 681, the surface is then rinsed with a neutral liquid such as deionized water dispensed by a rinse nozzle 1126 to remove the etched debris, any residual etchant, quenching chemical, and any by-products formed thereon. The optical device 10 with the wedge formed is then removed from the stage 1114 in operation 691 and placed in a cleaning and drying station 1128 having a spin rinse chuck 1130 in operation 692 to further rinse and dry the surface of the optical layer 30 where the 2D wedge 50c is formed.

[0050] In a second embodiment, to form the optical layer wedge 50b, a deeper etch is required in the area where the optical layer wedge 50b is to be formed, which is achieved by dispensing more droplets (increased droplet density) onto the optical layer 19 at the locations mentioned above, while fewer droplets (decreased droplet density) are emitted onto the optical layer 19 in the shallower areas of the optical layer wedge 50b to be formed. In operation 673, droplets of the inkjet dispenser 1104 of uniform etchant concentration are emitted to contact the optical layer 19 until the chemical reaction between the droplet chemicals and the optical layer is exhausted, and in the areas with fewer droplets, a smaller etch is made inwardly into the optical layer 19, and in the areas with a larger droplet emission, a larger etch is made inwardly into the optical layer 19. Thereafter, in operation 683, the surface of the optical layer 19 including the just-formed optical layer wedge 50b is washed with a neutral liquid, such as deionized water, dispensed by a cleaning nozzle 1126 to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. Thereafter, in operation 693, the optical device 10 is removed from the support 1114 and, in operation 694, placed in a cleaning and drying station 1128, after which the surface of the photoresist layer 30 on which the 2D wedge 50c was formed is further rinsed and dried.

[0051] In a third embodiment, etchant is released in various concentrations or molarities over the area where the optical layer wedge 50b is to be formed. In operation 675, droplets with a higher etchant concentration or molar concentration are released in the areas of the optical layer 19 that are to be etched to greater depths, and less concentrated droplets 1106 (diluted droplets) with a lower etchant or reactant content are released in the areas that are to be etched less, i.e., in the shallower optical layer wedge 50b areas. Then, in operation 685, the surface of the optical layer 19, now including the wedge 50b, is rinsed with a neutral liquid, such as deionized water dispensed by a rinse nozzle 1126 to remove etched debris, etchant, quenching chemicals, and any by-products formed therein. Thereafter, in operation 695, the optical device 10 is removed from the support 1114 and, in operation 696, placed in a cleaning and drying station 1128, after which the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and then dried.

[0052] In a fourth embodiment, etchant droplets having the same reactant or etchant concentration of different sizes are released in different parts of the area of ​​the optical layer 19 where the optical layer wedge 50b is to be formed. In operation 677, larger droplets are released in the deep etching area and smaller droplets are released in the shallower area of ​​the 2D wedge 50b, where the droplet size is changed by the inkjet dispenser 1104. The shallower side of the area where the depression forming the wedge is formed will receive the smaller etchant droplets 1106, and the deepest area of ​​the depression formed to form the optical layer wedge 50b will receive the largest droplets, and therefore the optical layer 19 will be etched to the deepest depth at that location. Thereafter, in operation 687, the surface of the optical layer 19 where the optical layer wedge 50b is formed is washed with a neutral liquid such as deionized water dispensed by the washing nozzle 1126 to remove etched debris, etchant, quenching chemicals, and any by-products formed thereon. Thereafter, in operation 697, the optical device 10 is removed from the support 1114 and, in operation 698, placed in a cleaning and drying station 1128, after which the surface of the photoresist layer 30 on which the 2D wedge 50c is formed is further rinsed and then dried.

[0053] 7A and 7B, there is shown a schematic side view of an optical device 10 including an overlying portion of the encapsulation layer 12 (FIG. 7A) and an opening 71 in the encapsulation layer 12 (FIG. 7B) formed by selectively removing the portion of the encapsulation layer by inkjet etching, where the device 10 is useful as a waveguide for use in virtual reality imaging and other applications, as previously described herein. Here, the optical device 10 includes the opening 71 in the encapsulation layer 12 above the intercoupler 15, where the opening 71 is formed using an 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 openings on the surface of the encapsulation layer 12, an optical device 10 having an encapsulation layer 12 of uniform thickness as shown in Figure 7A is mounted on a movable stage 1114 of an inkjet printer 1100 of Figure 11. To etch the encapsulation layer 12 to form openings 71 in desired areas of the encapsulation layer 12, here above the interposer 15, the stage 1114 is positioned under the droplet dispensing outlet 1108 of an inkjet dispenser 1104, with the side of the encapsulation layer 12 facing the device table of the inkjet etcher, and the stage 1114 rotates and moves in the X direction to position, under the droplet dispensing outlet 1110 of one or more inkjet dispensers 1104, a discrete portion of a location on the device 10 where the openings 71 are to be formed. The outlet nozzle 1108 facing the surface of the stage 1114 is located farther away from the droplet dispensing opening 1010 of the outlet nozzle 1008 of the inkjet nozzle than the thickness of the optical device 10, and the distance between the nozzle outlet and the surface of the encapsulation layer 12 of the optical device 10 is on the order of 2 to 5 mm.

[0055] Here, the opening 71 in the encapsulation layer exposes the underlying optical layer 19 within its perimeter, and the reactant or etchant for removing the encapsulation layer material should be very highly selective to etch the materials forming the encapsulation layer and the optical layer 19. Here, the interposers 15 of the optical layer 19 have a lattice of nanopillars 19a in the region 19b of the encapsulation layer 12 material extending between them. Thus, when the overlying portion of the encapsulation layer 12 is removed, the portion 19b will be removed or can be selectively removed. Examples of possible layer materials of the encapsulation layer 12 and suitable paired etchants for forming the opening 71 include the following pairs: SiO2 material with DHF etchant, Si3N4 material with HF or H3PO4 as etchant, TiO2 material with SC1 etchant, carbon-based material with 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, the material underlying the optical layer 19 and the substrate 21 on which the optical layer 19 is disposed act as an etch stop layer, since the etchant is preferably highly selective to etch the encapsulation layer material relative to the material of the substrate 21 and the material of the optical layer 19; This allows the encapsulation layer 12 above the intercoupler 15 and the region 19 b in the encapsulation layer 12 to be removed without adversely affecting the grating 19 b or the outer surface of the optical layer 19 .

[0057] To form the opening 71, an etchant is uniformly dispensed from the droplet dispensing outlet 1010 of the inkjet dispenser 1104 over the entire area where the opening 71 is to be formed, etching through the encapsulation layer 12 above the interlayer 15, and, if desired, once the surface of the optical layer 19 is exposed, portion 19b within the interlayer 15 can be removed by continuing to etch with the etchant or by adding additional droplets 1106 of the etchant. Once etching is complete (the results of which are shown in FIG. 7B where portion 19b of inkjet intercalator 15 has been removed), the reaction can be quenched, such as by providing a quenching chemical via a second line 1120b in FIG. 13 to neutralize the etchant and thereby stop the etching, where the etchant to be dispensed via droplet dispensing outlet 1110 of inkjet dispenser 1104 is provided via line 1120a, or the surface can be rinsed with a neutral liquid, such as deionized water dispensed from rinse nozzle 1126, to remove the etchant and stop the removal process. A quenching chemical can also be dispensed from rinse nozzle 1126. When washed with the neutral liquid from the rinse nozzle, the liquid removes the etched debris, any remaining etchant, the quenching chemical, and any by-products formed therein. The optical device 10 with the gap 71 formed therein is then removed from the stage 1114 and placed in a cleaning and drying station 1128 having a spin rinse chuck 1130 for further cleaning and drying. Alternatively, if the opening 71 has been formed but the region 19b of encapsulant material remains, the inkjet device 1100 can be controlled to dispense droplets 1106 of etchant only onto the top surface of the region 19b and not over the entire area of ​​the opening 71 to remove said region 19b of encapsulant material.

[0058] FIG. 8 is a flow chart illustrating a sequence of operations for creating an open gap 71 in encapsulation layer 12 over optical layer 19 of optical device 10, according to the process sequence described with respect to FIG.

[0059] First, in operation 801, the optical layer 19 coated with the encapsulation layer 12 is placed on a stage 1114, with the encapsulation layer 12 facing upward. Next, in operation 803, the stage 1114 is moved to position a desired location under the droplet dispensing outlet 1110 of the inkjet dispenser 1104 where an opening 71 is to be formed through the encapsulation layer 12. Several different strategies can then 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 released across the entire surface of the encapsulation layer 12, including where it is desired to form the opening 71. In operation 811, a quenching chemical is released at locations of the encapsulation layer where the etchant has reached but where an opening 71 is not desired. Once the depth of the opening is reached, i.e., the upper layer of the optical layer 19 is exposed, the etching is terminated in operation 821, such as by applying a quenching chemical to the exposed optical layer 19 and adjacent portions of the encapsulation layer 12 in the opening 71, by applying a rinsing liquid such as deionized water to wash away the etchant, or a combination thereof. The device is then moved to a cleaner in operation 831, where it is washed and dried in operation 841.

[0061] In another embodiment, in operation 813, etchant droplets of uniform size and uniform etchant concentration are released only at locations in the encapsulation layer 12 where openings 71 are desired. Once the opening depth is reached through the encapsulation layer 12 where the optical layer 19 is exposed, the etching is terminated in operation 823, such as by applying a quenching chemical to the exposed optical layer 19 in the openings 71 and adjacent portions of the encapsulation layer 12, by applying a rinsing liquid such as deionized water to wash away the etchant, or a combination thereof. The device is then moved to a cleaner in operation 833 where it is washed and dried in operation 843.

[0062] In another embodiment, in operation 807, droplets of buffer having uniform size and uniform etchant concentration are released over the entire optical device 10 except at the location of the encapsulation layer 12 where the opening 71 is desired. In operation 815, droplets having a constant concentration of etchant are released over the entire encapsulation layer 12 or over at least a portion of the encapsulation layer 12 that is larger than the area of ​​the opening 71 being formed. Once the depth of the opening is reached, i.e., the optical layer 19 in the opening 71 is exposed, the etching is terminated in operation 825, such as by applying a quenching chemical to the opening 71 and adjacent portions of the encapsulation layer 12, by applying a rinsing liquid such as deionized water to wash away the etchant, or a combination thereof. The device is then moved to a cleaner in operation 835, where it is washed and dried in operation 845.

[0063] 9A and 9B, schematic side views of an optical device 10 are shown including an anomaly in a membrane layer or in the thickness of a membrane layer (FIG. 9A) and a smoothed anomaly in the thickness of an encapsulation layer (FIG. 9B). The optical device 10 of FIG. 9A includes a thickness anomaly 91 in the encapsulation layer 12, which is now modified using an inkjet wet etcher 1100 that dispenses an etchant to selectively and locally remove material from the encapsulation layer to form a smooth horizontal surface of the encapsulation layer 12 of FIG. 9B.

[0064] To correct anomalies in thickness, here anomalies 91, or undesired extensions of the encapsulation layer 12 above a desired upper plane and extending onto the surface of the encapsulation layer 12, an optical device 10 having anomalies 91 is mounted on a movable stage 1114 of an inkjet printer 1100 of Figure 11. The printer 1100 here acts as a localized dispenser of etchant or reactant to the encapsulation layer 12 of the device 10, capable of removing or etching away discrete portions of the material of the encapsulation layer 12. The printer 1102 includes a table 1102 supported on and movable in an X-direction relative to a base 1112 thereof, and at least one inkjet-type dispenser 1104, here four such dispensers 1104a-d, each of which is configured to dispense droplets 1106 of liquid material therefrom and has an outlet nozzle 1108 selectively facing towards the table 1102. A stage 1114 is rotatably coupled to the table 1102, for example via a shaft (not shown) connected to a stepper motor (not shown) in the table 1102, such that the stage 1114 is rotatable about its center 1116 in a θ-direction in FIG. To etch the dielectric layer encapsulation layer 12 to remove the thickness anomaly 91 in a desired area of ​​the encapsulation layer 12, i.e., here across the thickness of the device 10, a stage 1114 is positioned under the outlet 1108 of the inkjet dispenser 1104 of the droplet dispensing outlet 1110 of the inkjet etcher 1100, with the side of the encapsulation layer 12 facing towards the device table of the outlet nozzle 1108 of the inkjet etcher, and the stage 1114 is rotated and moved in the X direction to position under the outlet 1108 of one or more inkjet dispensers 1104 an individual portion or location on the device 10 where an anomaly has formed and is to be removed.The outlet nozzle 1008 facing the surface of the stage 1114 is located farther away from the droplet dispensing opening 1010 at the outlet of the outlet nozzle 1008 of the inkjet nozzle than the thickness of the optical device 10, and the distance between the nozzle outlet and the surface of the encapsulation layer 12 of the optical device 10 is on the order of 2 to 5 mm.

[0065] Droplets 1106 of a wet etchant or reactive chemical are dropped onto the protrusion 91 from one or more outlets 1108 of the inkjet device 1104 to correct the anomaly 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. Examples of possible layer materials of the encapsulation layer 12 and their suitable paired etchants include the following pairs: SiO2 material with DHF etchant, Si3N4 material with HF or H3PO4 as etchant, TiO2 material with SC1 etchant, carbon-based material with organic solvent or photoresist removal etchant, and aSI (amorphous silicon) material using KOH etchant. Etching of the anomaly 91 of the 2D wedge 11 can be done in the membrane layer and can be performed in a variety of different ways.

[0066] Here, imaging cameras 1130, 1132 are provided in the inkjet device 1100, which are used to identify the location of an abnormal portion 91 on the encapsulation layer 12, enabling the inkjet device 1100 to position the abnormal portion 91 directly below the droplet dispensing outlet 1110, so that the emitted droplets of etchant fall on the abnormal portion 91 rather than on the surrounding encapsulation layer 12, and further, the imaging cameras 1130, 1132 can be used in conjunction 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. As the abnormality 91 is etched away by application of the etchant droplets 1106, the contours of the abnormality 91 and its position are monitored using cameras 1130, 1132, enabling the stage 1114 to accurately position the abnormality 91 under the droplet dispensing outlet 1110 and ensuring that the droplets 1106 fall on the abnormality 91 and the portion of the abnormality 91 that extends furthest above the otherwise flat, uniform surface 93 of the encapsulation layer 12, rather than on adjacent portions of the encapsulation layer 12. 9B, once the abnormal portions 91 have been removed down to an otherwise uniform surface 93 of the encapsulation layer, the etching is terminated by, for example, rinsing the surface of the encapsulation layer 12 and the exposed portions of the optical layer 19 with a quenching chemical dispensed by an inkjet dispenser 1124 and droplet dispensing opening 1110, with a neutral liquid such as deionized water dispensed through a rinse nozzle 1126, or by rinsing with the quenching chemical followed by a neutral liquid wash using, for example, deionized water. The device is then removed from the stage and mounted in a cleaning and drying station 1128 for cleaning and drying of the device.

[0067] FIG. 10 is a flow chart providing a sequence of operations used to remove an anomaly 91 extending above a surface 93 of a membrane layer such as an encapsulation layer 12. First, in operation 1001, the device 10 including the anomaly is positioned on a stage 1114 of an inkjet etcher 1100. Next, in operation 1003, the location of the anomaly on the encapsulation layer is confirmed using cameras 1130, 1132, and the stage 1114 is moved to position the anomaly under a droplet dispensing outlet 1110 of an inkjet dispenser 1104 in operation 1003. Next, droplets of etchant are dispensed only on the surface of the protrusion in operation 1005, similar to the process for creating a 2D wedge described in FIG. 2. The droplets are ejected using the same four strategies described in FIG. 2, plus one new additional strategy in operation 1019. The above strategies include removing anomalies 91 by quenching modification as described in operations 1011-1041, removing anomalies 91 by modifying droplet density as described in operations 1013-1043, removing anomalies 91 by modifying concentration as described in operations 1015-1045, and removing anomalies 91 by modifying droplet size as described in operations 1017-1047. The above etching procedures follow the same pattern to form larger or smaller etchings into the desired resulting structure. If a 2D wedge is to be created, the wedge can be etched into the already flat surface of the encapsulation layer 12, and if an anomaly is to be corrected, removing the anomaly 91 to create a flat uniform surface 93 of the encapsulation layer 12 may be the desired result. Thus, here, droplets 1106 of etchant are deposited successively on the portions of the anomaly 91 that extend furthest from the underlying desired flat uniform surface 93, and their positions will change as the anomaly is removed. In operation 1019, etchant droplets of uniform size, density, and concentration are released at the most prominent point of an anomaly 91 on the desired flat, uniform surface 93 of the encapsulation layer 12, which may or may not be the center of the anomaly.As the etching continues, cameras 1130 and 1132 locate the most prominent portion of the anomaly 91 on the desired flat, uniform surface 93 of the encapsulation layer 12, and the stage 1114 of the inkjet etcher 1100 is moved to position the most prominent portion of the anomaly 91 under the droplet dispensing outlet 1110 of the inkjet dispenser 1104. Droplets are then dispensed again, and the sequence of locating the most prominent portion of the anomaly and dispensing droplet 1106 thereat is repeated until the anomaly 91 is coplanar with the desired flat, uniform surface 93 of the encapsulation layer 12. Once this planarity is reached, the etching is terminated in operation 1029, such as by applying a quenching chemical to the anomaly 91 and adjacent portions of the encapsulation layer, by applying a rinse liquid such as deionized water to wash away the etchant, or a combination thereof. The device is then moved to a cleaner in operation 1039 where it is washed and dried in operation 1049 .

[0068] 12A and 12B, there are shown schematic side views of an optical device 10 including a uniform encapsulation layer 12 (FIG. 12A) and an optical device 10 with a 1D wedge 121 (FIG. 12B) formed in the encapsulation layer 12. 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 to dispense an etchant to selectively and locally remove material from the encapsulation layer to form the smooth, angled surface of the encapsulation layer 12 of FIG. 12B. Here, in contrast to the 2D wedge structures described earlier herein, where the depth of the surface feature etched in the Z direction into the surface of the layer varies in both the X and Y directions, here the depth of the surface etched in the Z direction into the surface of the layer varies in only one of the X and Y directions, resulting in a ramp-like feature with a planar outer surface, i.e., a simple 1D wedge. As described herein, the depth of a feature varies only in the X direction and is constant across any Y direction, with the depth of the feature varying at adjacent Y locations that are adjacent to each other in the X direction. This is accomplished by performing the same material removal across each Y section of the feature, and increasing or decreasing material removal at adjacent Y locations of the feature. As described herein, this can be accomplished in a number of ways, including applying a blanket material remover, or etchant, to the entire area of ​​the surface where the wedge is to be formed, and selectively quenching the reaction across the Y direction of the surface, which is the X direction of the feature. o X in the area starting from the end e 1, where the n regions extend in the Y direction across the area where the feature is to be formed, for example, the individual regions Y1-Y in the X direction may be spaced apart to allow for the individual regions extending in the Y direction across the area where the 1D wedge 121 is to be formed to have the same quench timing or exposure of the underlying material during the etchant (with adjacent regions having different quench timings) or exposure of the underlying material during the etchant. nIn FIG. 12C, region Yo has the earliest quench timing, i.e., it is quenched before any other region is quenched, the next region Y1 has the next earliest quench timing, and each of the adjacent regions Y2 to Y n has a correspondingly longer quench timing. As a result, the region Y o The Z-direction depth of the region Y1 is shallower than the Z-direction depth of the region Y2, and the Z-direction depth of the region Y2 is shallower than the Z-direction depth of each of the subsequent regions Y3 to Y4. n The Z-direction depth of the area Y n-1 The depth in the Z direction of the area Y n In this manner, features are formed on the surface of the encapsulation layer 12 that have inwardly extending sloping outer surfaces. n The smaller the width in the X direction of each of the n 1D wedge 121 has a smoother transition to depth, which causes the width of each Y region in the X direction to approach 0 and makes the outer surface of 1D wedge 121 more planar.

[0069] In another embodiment, a 1D wedge 121 may be formed by varying the density of dispensed etchant droplets in the X direction, but maintaining the same density of droplets in the Y direction at each X location. As etchant is consumed by reaction with the underlying material to form the wedge, the etch rate slows and may reach zero in areas where fewer droplets are dispensed, but in areas where the wedge feature is etched deeper into the layer, i.e., where more droplets are dispensed in the X direction than in adjacent Y areas, etching may continue inward into the layer to form a 1D wedge 121 as shown in Figures 12B and 12C. Again, droplets 1106 may etch inwardly in the X direction from area Y. o ~Y n where the number of droplets in each distinct Y region is the same but the number of droplets in adjacent Y regions in the X direction is different, thus forming a wedge feature having the characteristics of Figures 12B and 12C.

[0070] In another embodiment, the 1D wedge 121 changes the etchant concentration in droplets dispensed in adjacent Y regions in the X direction, but again in the Y regions. o ~Y n The etchant droplets 1106 are formed by maintaining the etchant concentration of the droplets 1106 in each of the regions Y constant in the Y direction. Similarly, the size of the etchant droplets can be varied over the region of the wedge 121 being formed, where the etchant concentration in the droplets is the same. Thus, o Deposit the smallest droplets over the entire area, and then each subsequent area Y o ~Y n By gradually increasing the size of the droplet within the cavity, the wedge feature of Figures 12B and 12C can be formed.

[0071] Figure 13 is a flow chart showing a sequence of operations for fabricating a 1D wedge 121 in the encapsulation layer 12 of the optical device 10, according to the sequence of processes described with respect to Figure 12. First, the optical layer 19 is prepared. However, the encapsulation layer 12 may need to be modified in thickness to produce the desired effect for the optical device 10, and thus the formation of the 1D wedge 121 may take place. A processing sequence for forming a 1D wedge in the encapsulation layer 12 will now be described.

[0072] In operation 1301, the optical device 10 is placed on a stage 1114, and in operation 1303, the stage 1114 in the inkjet wet etching apparatus 1100 is positioned by motion in the X and θ directions of FIG. 11 under a droplet dispensing opening 1110 of an outlet nozzle 1108 of an inkjet dispenser 1104 to position a desired location on the encapsulation layer 12 where a 1D wedge is to be formed. 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 opening. Preferably, the etchant has an etch rate of the material of the optical layer 19 that is about 100 times or more slower than the etch rate of the encapsulation layer 12 when exposed to the same etchant.

[0073] In one embodiment, in operation 1311, after an etchant is discharged via line 1118a to outlet nozzle 1108a to cover the entire area where wedge profile 11a for forming wedge 121 is to be formed, a quenching chemical is immediately discharged onto region Y0 of wedge profile 11a being formed. The higher numbered Y regions of the encapsulation layer of wedge profile 11a being formed then sequentially receive the quenching chemical by movement of stage 1114 to position individual regions of encapsulation layer 12 under stream of quenching chemical droplets 1106 at predetermined times, at which time wedge profile 121a has had enough material removed to form the desired encapsulation layer 12 thickness of wedge profile 11a, where the amount of material removed is the same in the Y direction and varies in the X direction, resulting in a planar feature extending into layer 12 in the Z direction at a constant rate per length in the X direction. Once the entire surface of the encapsulation layer 12 in the region of the wedge contour 11a has been quenched, in operation 1321, the surface is rinsed with deionized water dispensed by rinse nozzle 1126 to remove the etched debris, any residual etchant, quenching chemicals, and any by-products formed therein. In operation 1331, the optical device 10 with the wedge 11 formed thereon is then removed from stage 1114 and placed in operation 1341 in a cleaning and drying station 1128 having a spin rinse chuck 1130 for further cleaning and drying.

[0074] In a second embodiment, a deeper etch dispenses more and more droplets in adjacent Y regions with increasing subscript numbers in the X direction, but not in region Y. o ~Y n This is achieved by maintaining a constant etchant droplet density in the Y direction of the region Y. o The droplets are deposited with the minimum density over the entire area, and each subsequent area Y o ~Y n12B and 12C may be formed by moving the stage 1114 under the stream of droplets 1106, and thus the encapsulation layer 12. Alternatively, if the viscosity of the droplets is relatively high and they do not move significantly from their deposited position on the encapsulation layer, a single pass of the wedge contour 121a forming the region of the encapsulation layer 12 under the droplet dispensing outlet 1010 may cause more droplets 1106 to fall on the deeper portions of the wedge contour 121a than on the shallower regions of the wedge contour 11a, such that a thicker layer of etchant is present over the deeper portions of the wedge contour 11a to be formed than on the shallower regions of the wedge contour 11a. Thereafter, in operation 1323, the surface of the encapsulation layer 12, including the 1D wedge 121, is washed with deionized water dispensed by the washing nozzle 1126 to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. Thereafter, in operation 1333, the optical device 10 is removed from the support 1114 and, in operation 1343, placed in the washing and drying station 1128 for further washing and drying.

[0075] In a third embodiment, in operation 1305, etchant is released in droplets 1106 of various etchant concentrations at various locations of the wedge contour 121a to be formed. The droplets are dispensed into Y regions that are adjacent in the X direction, again with the regions Y being spaced apart from each other. o ~Y n In the Y direction of the droplet, the etchant concentration is maintained constant. Thus, in operation 1315, o Deposit droplets of minimum concentration throughout the entire region, and then deposit droplets in each subsequent region Y. o ~Y n12B and 12C may be formed by gradually increasing the concentration of droplets in the 1D wedge 121. The surface of the encapsulation layer 12 including the 1D wedge 121 is then rinsed with deionized water dispensed by a rinse nozzle 1126 in operation 1325 to remove etched debris, etchants, quenching chemicals, and any by-products formed therein. The optical device 10 is then removed from the support 1114 in operation 1335 and placed in a cleaning and drying station 1128 in operation 1345 for further cleaning and drying.

[0076] In a fourth embodiment, the etchant released in act 1305 dispenses larger droplets in adjacent Y regions in the X direction, but in act 1317, the etchant in region Y o ~Y n By maintaining a constant size of the etchant droplets in the Y direction of the etching, a deeper etch is achieved. Therefore, the smallest size droplets are deposited over the entire region Y and each subsequent region Y o ~Y n 12B and 12C may be formed by gradually increasing the droplet size within the nozzle 1126. Thereafter, in operation 1327, the surface of the encapsulation layer 12 on which the 1D wedge 121 is formed is washed with deionized water dispensed by the washing nozzle 1126 to remove etched debris, etchants, quenching chemicals, and any by-products formed thereon. Thereafter, in operation 1337, the optical device 10 is removed from the support 1114 and, in operation 1347, placed in the washing and drying station 1128 for further washing and drying.

[0077] In at least some embodiments herein, surfactants are used to modify the etching capabilities of the aforementioned etching strategies. Surfactants are used to modify the surface energy of the droplets. If the surface energy of the droplet is smaller than the surface energy of the surface that will receive it, the droplet will spread. The higher the surface energy of the droplet compared to the surface energy of the surface onto which it is deposited, the less the droplet will spread. Thus, here, the local mixing of adjacent droplets on the surface to be etched or on the surface being etched can be altered by selectively adding surfactants thereto, which allows dispensed droplets adjacent to each other to merge or remain substantially isolated from each other.

[0078] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the following claims. The present application includes the following aspects. (Aspect 1) 1. A method of forming a patterned photoresist on a layer of material, comprising: providing a droplet dispenser including an outlet configured to dispense individual droplets of a liquid material; providing a support configured to support the layer of material thereon, the support and the droplet dispenser being movable relative to one another, the outlet of the droplet dispenser being positionable over various discrete areas of a surface of the material; providing a first liquid dispensable in droplet form from the droplet dispenser, the first liquid including a photoresist polymer; 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 to dispense droplets of the first liquid onto the entire surface of the layer of material in discrete portions; and dispensing droplets of the second liquid onto only desired discrete areas of the layer of material to mix the first liquid and the second liquid within the desired discrete areas of the layer of material; A method comprising: (Aspect 2) 2. The method of embodiment 1, wherein within the discrete areas, different amounts of the first liquid are dispensed into different portions of the discrete areas. (Aspect 3) 3. The method of claim 2, wherein multiple sublayers of the first liquid are successively coated onto the layer of material, with the first and subsequent sublayers being formed one above the other on the layer of material, and the portion of the discrete areas that receive the second liquid increasing from the first sublayer to the last sublayer being formed.

Claims

1. 1. A method for forming three-dimensional features inwardly on a 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 reactive substance capable of reacting with and thereby removing portions of the material with which the droplet contacts; providing a support configured to support the material thereon, the support and the droplet dispenser being movable relative to one another, the outlet of the droplet dispenser being positionable over various discrete areas of the surface of the material; positioning the surface of the material under the droplet dispenser to dispense droplets onto discrete portions of the surface of the material within a desired area of ​​the material to remove at least a portion of the material within the desired area to form a three-dimensional recess inwardly in the surface of the material; providing droplets having different concentrations of said reactant to different discrete portions of said desired area; A method comprising:

2. The method of claim 1 , further comprising dispensing droplets of different amounts of the liquid material onto different portions of the desired area.

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

4. the droplets of the liquid material dispensed from the droplet dispenser have a uniform concentration of the reactant; the droplet of liquid is dispensed over the desired area; 10. The method of claim 1, wherein a quenching chemistry is applied to the desired area over a period of time, such that portions of the desired area from which a greater amount of material is to be removed receive etchant at a later time than portions of the desired area from which a lesser amount of material is to be removed.

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

6. 2. The method of claim 1 , wherein droplets having a higher concentration of reactant are dispensed into discrete portions of the area where the three-dimensional feature being formed is to be deeper, and droplets having a lower concentration of reactant are dispensed into discrete portions of the area where the three-dimensional feature being formed is to be shallower than the deeper portions.

7. The method of claim 1 , further comprising providing droplets of different volumes to different discrete portions of the desired area.

8. 8. The method of claim 7, wherein larger volume droplets are dispensed in discrete portions of areas where the three-dimensional feature being formed is to be deeper, and smaller volume droplets are dispensed in discrete portions of areas where the three-dimensional feature being formed is to be shallower than the deeper portions.

9. The method of claim 1 , wherein the surface of the material is an abnormal feature, and further comprising dispensing a droplet to form a three-dimensional feature inwardly onto the surface of the abnormal feature.

10. 10. The method of claim 1, wherein the material is disposed over an underlying second material, and the first material is removed in the area to expose an underlying surface of the underlying second material.

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