Nanoimprint and etch fabrication of optical devices

Abstract

A method for forming optical elements using nanoimprint lithography and etching processes is provided. In one embodiment, a method includes depositing a first resist layer on a substrate having a hard mask disposed thereon; imprinting a first resist portion of the first resist layer with a first single-height mold; etching the first resist portion of the first resist layer; etching a first hard mask portion of the hard mask corresponding to the first resist portion of the first resist layer; removing the first resist layer and depositing a second resist layer; imprinting a second resist portion of the second resist layer with a second single-height mold; etching the second resist portion of the second resist layer; and etching a second hard mask portion of the hard mask corresponding to the second resist portion of the second resist layer.

Description

Technical Field

[0001] The embodiments of the present invention are generally related to the manufacture of optical elements. In particular, the embodiments described herein relate to a method for forming optical elements using nanoimprint lithography and etching processes. Prior Technology

[0002] Structures using optical elements formed on a substrate can be used to manipulate the propagation of light. These structures alter light propagation by inducing local phase discontinuities (i.e., abrupt phase changes at distances smaller than the wavelength of light). These structures can be comprised of different types of materials, shapes, or configurations on the substrate, and they can operate based on different physical principles. The spacing and critical dimensions of these structures determine their operating cycle.

[0003] The fabrication of optical components may include nanoimprint lithography. Nanoimprint lithography involves a patterned master or stencil. The pattern of the stencil determines the pattern that is imprinted into the resist material and subsequently etched into the component layer or substrate. When features with different operating cycles are imprinted onto a single optical component substrate, the residual layer formed by nanoimprint lithography can be non-uniform, resulting in reduced overall uniformity.

[0004] Therefore, what is needed in this field is a method for forming optical elements using nanoimprint lithography and etching processes. Summary of the Invention

[0005] A method for forming optical elements using nanoimprint lithography and etching is provided. In one embodiment, the method includes depositing a first resist layer on a substrate having a hard mask disposed thereon; imprinting a first resist portion of the first resist layer with a first single-height mold; etching the first resist portion of the first resist layer; etching a first hard mask portion of the hard mask corresponding to the first resist portion of the first resist layer; removing the first resist layer and depositing a second resist layer; imprinting a second resist portion of the second resist layer with a second single-height mold; etching the second resist portion of the second resist layer; and etching a second hard mask portion of the hard mask corresponding to the second resist portion of the second resist layer.

[0006] In another embodiment, the provided method includes depositing a first resist layer on a substrate through a spin-coating deposition process, the first resist layer having a first resist portion and a second resist portion, imprinting the first resist layer with a single-height mold, depositing a barrier layer on the second resist portion of the first resist layer, etching the first resist portion of the first resist layer, depositing a barrier layer on the first resist portion of the first resist layer, removing the barrier layer, and etching the second resist portion of the first resist layer.

[0007] In another embodiment, the provided method includes depositing a first resist layer on a substrate having a hard mask and component material disposed thereon through a spin-coating deposition process; imprinting a first resist portion of the first resist layer with a single-height die; etching the first resist portion of the first resist layer; etching a first hard mask portion of the hard mask corresponding to the first resist portion of the first resist layer; removing the first resist layer and depositing a second resist layer; imprinting a second resist portion of the second resist layer with a single-height die; etching the second resist portion of the second resist layer; and etching a second hard mask portion of the hard mask corresponding to the second resist portion of the second resist layer. Simple Explanation of the Diagram

[0008] A more detailed description of the invention briefly summarized above can be obtained by referring to some of the embodiments illustrated in the accompanying drawings, thereby allowing a detailed understanding of the above-described features of the invention. However, it will be noted that the accompanying drawings are merely exemplary embodiments and are therefore not intended to limit the scope of the invention, and other equivalent embodiments are permissible.

[0009] Figures 1A and 1B are schematic anatomical views of a portion of an optical element substrate according to one or more embodiments.

[0010] Figure 2 illustrates a method for patterning an optical element substrate according to one or more embodiments.

[0011] Figures 3A-3H are anatomical views of a portion of an optical element substrate according to one or more embodiments.

[0012] Figure 4 illustrates a method for patterning an optical element substrate according to one or more embodiments.

[0013] Figures 5A-5E are anatomical views of a portion of an optical element substrate according to one or more embodiments.

[0014] For ease of understanding, the same element symbols have been used as much as possible to refer to the same common elements in the illustrations. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further explanation. Implementation

[0015] The embodiments of the present invention are generally related to the manufacture of optical elements. In particular, the embodiments described herein relate to a method for forming optical elements using nanoimprint lithography and etching processes.

[0016] Figures 1A and 1B are schematic cross-sectional views of a portion 100 of an optical element substrate 101 according to one or more embodiments. The optical element substrate 101 may be manufactured as an optical element. In one embodiment that can be combined with other embodiments described herein, the optical element formed from the optical element substrate 101 is a waveguide combiner, such as an extended waveguide combiner. In another embodiment that can be combined with other embodiments described herein, the optical element formed from the optical element substrate 101 is a planar optical element, such as a metasurface. The optical element substrate 101 may be formed of any suitable material, provided that the optical element substrate 101 can suitably transmit light at a desired wavelength or wavelength range. Substrate selection may include substrates of any suitable material, including but not limited to amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics, silicon oxide, polymers, and combinations thereof. In some embodiments that can be combined with other embodiments described herein, the optical element substrate 101 includes a transparent material. In one embodiment that can be combined with other embodiments described herein, the optical element substrate 101 includes silicon (Si), silicon dioxide (SiO2), silicon carbide (SiC), germanium (Ge), silicon germanide (SiGe), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), fused silica, quartz, or sapphire. In another embodiment that can be combined with other embodiments described herein, the optical element substrate 101 includes a high-index transparent material, such as high-refractive-index glass.

[0017] In one embodiment that can be combined with other embodiments described herein, element material 102 is disposed on optical element substrate 101. Element material 102 can be used to form a plurality of optical element structures on optical element substrate 101, as shown in Figures 3H and 5E. Element material 102 includes, but is not limited to, one or more materials containing silicon carbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium oxide (IV)(VOx), aluminum oxide (Al2O3), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO2), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), zirconium dioxide (ZrO2), niobium oxide (Nb2O5), cadmium stannate (Cd2SnO4), or silicon carbide (SiCN).

[0018] In one embodiment that can be combined with other embodiments described herein, a hard mask 103 is disposed over the element material 102 or the optical element substrate 101. The hard mask 103 is used to pattern the underlying material, i.e., the element material 102 or the optical element substrate 101. The hard mask 103 includes, but is not limited to, silicon nitride (SiN), silicon oxide (SiO), silicon carbide (SiOC), tantalum oxide (Ta₂O₅), borosilicate glass (BPSG), phosphosilicate glass (PSG), dielectrics, metals, or metallic alloys. In one embodiment that can be combined with other embodiments described herein, the metal may be chromium (Cr). In another embodiment that can be combined with other embodiments described herein, the metallic alloy may be titanium nitrate (TiN).

[0019] A first resist layer 105 disposed on the hard mask 103 is an imprintable material that can be patterned by nanoimprinting to form a plurality of resist structures 106. In one embodiment that can be combined with other embodiments described herein, the first resist layer 105 is a nanoimprinted resist. Each resist structure 106 has a spacing 130, a height 132, and a critical dimension 140. The spacing 130 is determined by the distance between the first edges of the resist structures 106. A first wetting layer 104 is optionally disposed between the hard mask 103 and the first resist layer 105. The first wetting layer 104 improves the adhesion of the first resist layer 105, particularly when the first resist layer 105 is deposited by spin coating.

[0020] Adjacent resist structures 106 of a plurality of resist structures 106 have a working cycle. This working cycle is determined by dividing a critical dimension 140 of the resist structure 106 by a spacing 130. The critical dimension 140 may be the width or diameter of the resist structure 106. As depicted in Figure 1A, different portions of the resist structure 106 may have different working cycles, depending on the state of the nanoimprinting process or on the optical design. For example, a first resist layer 105 and a first resist portion 111 of the resist structure 106 have a first working cycle, and a first resist layer 105 and a second resist portion 112 of the resist structure 106 have a second working cycle. In one embodiment that can be combined with other embodiments described herein, the second working cycle is greater than the first working cycle. In another embodiment that can be combined with other embodiments described herein, the first working cycle is greater than the second working cycle.

[0021] The duty cycle value causes variation between the thickness 121 of the first residual layer 120 and the thickness 123 of the second residual layer 122 formed in the first resist layer 105 through nanoimprint processing. Generally, lower duty cycle features have thicker residual layers, such as the first residual layer 120, while higher duty cycle features have thinner residual layers, such as the second residual layer 122. When the patterned resist structure 106 is etched, the second resist portion 112 with the lower duty cycle is over-etched before the first resist portion 111 is etched beyond the first residual layer 120. As depicted in Figure 1B, over-etching causes a loss of resolution in the resist structure 106 in the second resist portion 112. The resolution of the resist structure 106 affects the final optical element formed on the optical element substrate 101.

[0022] Figure 2 shows a method 200 for patterning an optical element substrate 101. Figures 3A-3H are anatomical views of a portion 100 of the optical element substrate 101.

[0023] The method 200 described herein creates a residual layer thickness such that the pattern formed in the resist layer can withstand etching. By resisting etching, an optical element structure with improved uniformity and resolution can be fabricated. In operation 201, a first resist layer 105 is deposited on an optical element substrate 101 having a hard mask 103 disposed thereon. The first resist layer 105 is deposited by any suitable method, such as spin coating, slot coating, or inkjet material deposition. In one embodiment that can be combined with other embodiments described herein, a first wetting layer 104 is deposited on the hard mask 103 and below the resist layer 105. In one embodiment that can be combined with other embodiments described herein, element material 102 is deposited on the optical element substrate 101 and below the hard mask 103.

[0024] In operation 202, as shown in Figure 3A, a mold 301 is used to imprint the first resist portion 111 of the first resist layer 105. The mold 301 is a single-height mold, wherein a plurality of features 302 of the mold 301 are substantially the same height. When imprinting different areas of the optical element substrate 101, resist structures 106 with different duty cycles are formed by applying different forces to the single-height mold 301. However, as discussed above with respect to Figures 1A and 1B, the lower duty cycle features have a thicker residual layer 120, while the higher duty cycle features have a thinner residual layer 122. If the entire resist structure 106 is etched in the same operation, the difference in thickness of the residual layers 120, 122 will cause over-etching. The method 200 described herein allows the use of a single-height mold 301 or master film while preventing over-etching, critical dimension (CD) drift, and substrate film corrosion.

[0025] Patterning the first resist portion 111 of the first resist layer 105 results in the formation of a resist structure 106 having a spacing 130 and a critical dimension 140. Furthermore, an embossing process results in the formation of a first resist layer 120 having a thickness 121. As described above, the thickness 121 of the first resist layer 120 corresponds to the operating cycle of the resist structure 106.

[0026] In operation 203, as shown in Figure 3B, the first residual layer 120 of the first resist portion 111 of the resist layer 105 is etched. The first resist layer 120 of the first resist portion 111 is etched through the area surrounding the resist structure 106. The etching process may include one or more of ion beam etching, electron beam etching, or wet etching. In one embodiment that may be combined with other embodiments described herein, the etching of the first residual layer 120 exposes a first wetting layer 104, which is then removed by one or more of dry ashing, dry etching, or wet etching. In another embodiment that may be combined with other embodiments described herein, the etching of the first residual layer 120 exposes a hard mask 103.

[0027] In operation 204, as shown in Figure 3C, the first hard mask portion 311 of the hard mask 103 corresponding to the first resist portion 111 of the first resist layer 105 is etched by one or more of ion beam etching or electron beam (e-beam) etching. Using a resist structure 106 patterned in the first resist layer 105, the hard mask 103 is etched through openings in the patterned first resist layer 105. The patterned hard mask 103 corresponds to a pattern imprinted in the first resist layer 105 by an impression 301.

[0028] In operation 205, as shown in Figure 3D, the first resist layer 105 is removed, and a second resist layer 305 is deposited on the hard mask 103. The first resist layer 105 is removed by one or more of dry ashing, dry etching, or wet etching. The second resist layer 305 covers the etched structure of the first hard mask portion 311 of the hard mask 103. In one embodiment that can be combined with other embodiments described herein, a second wetting layer 304 is disposed on the hard mask 103 and below the second resist layer 305.

[0029] In operation 206, as shown in Figure 3E, the second resist portion 112 of the second resist layer 305 is imprinted. In one embodiment that can be combined with other embodiments described herein, the same mold 301 is used in operation 206 to imprint the second resist portion 112 of the second resist layer 305 used in operation 202. In another embodiment that can be combined with other embodiments described herein, a first mold 301 is used in operation 206, while a second mold 303 is used in operation 202 to imprint the second resist portion 112 of the second resist layer 305. The first mold 301 and the second mold 303 are characterized by a single height.

[0030] In operation 207, as shown in Figure 3F, the second residual layer 122 corresponding to the second resist portion 112 of the second resist layer 305 is etched by one or more of ion beam etching or electron beam etching. The second residual layer 122, having a thickness of 123, is etched through the area surrounding the resist structure 106. In one embodiment that can be combined with other embodiments described herein, the etching of the second residual layer 122 exposes a second wetting layer 304, which is then removed by one or more of dry ashing, dry etching, or wet etching. In another embodiment that can be combined with other embodiments described herein, the etching of the second residual layer 122 exposes a hard mask 103.

[0031] In operation 208, as shown in Figure 3G, the second hard mask portion 312 of the hard mask 103 corresponding to the second resist portion 112 of the second resist layer 305 is etched by one or more of ion beam etching or electron beam (e-beam) etching. Using a resist structure 106 patterned in the second resist layer 305, the hard mask 103 is patterned and etched through openings in the patterned second resist layer 305. The patterned hard mask 103 corresponds to a pattern imprinted in the second resist layer 305 by an impression 301.

[0032] After etching the hard mask 103 in operation 208, the optical element substrate 101 undergoes further processing to form a plurality of optical element structures 320. In one embodiment, as shown in Figure 3H, element material 102 is etched through the hard mask 103 to form a plurality of optical element structures 320 on the optical element substrate 101 from element material 102. In another embodiment, which can be combined with other embodiments described herein, the plurality of optical element structures 320 are formed by etching the optical element substrate 101. A first resist portion 111 of a first resist layer 105 corresponds to a first optical element structure 330, and a second resist portion 112 of a second resist layer 305 corresponds to a second optical element structure 340. The first optical element structure 330 has a first operating cycle, while the second optical element structure 340 has a second operating cycle different from the first operating cycle.

[0033] In one embodiment that can be combined with other embodiments described herein, the mold 301 is a negative pattern of the first optical element structure 330 and the second optical element structure 340. In another embodiment that can be combined with other embodiments described herein, the first mold 301 is a negative pattern of the first optical element structure 330, and the second mold 303 is a negative pattern of the second optical element structure 340.

[0034] Figure 4 shows a method 400 for patterning an optical element substrate 101. Figures 5A-5E are anatomical views of a portion 100 of the optical element substrate 101.

[0035] In operation 401, a resist layer 105 is deposited on an optical element substrate 101, the optical element substrate 101 having a hard mask 103 disposed thereon. In one embodiment that can be combined with other embodiments described herein, a first wetting layer 104 is disposed beneath the first resist layer 105. In another embodiment that can be combined with other embodiments described herein, element material 102 is disposed on the optical element substrate 101 and beneath the hard mask 103.

[0036] In operation 402, as shown in Figure 5A, a first resist portion 111 and a second resist portion 112 of a first resist layer 105 are imprinted using a mold 301. The mold 301 is a single-height mold, characterized in that it is substantially of the same height. The patterning of the first resist portion 111 of the first resist layer 105 results in the formation of a resist structure 106 having a spacing 130 and a critical dimension 140.

[0037] In operation 403, as shown in Figure 5B, a barrier layer 501 is disposed over the second resist portion 112 of the first resist layer 105. The barrier layer 501 covers the second resist portion 112 while the first resist portion 111 of the first resist layer 105 is etched in operation 404. The barrier layer 501 may include at least one photoresist. In one embodiment that can be combined with other embodiments described herein, the photoresist may include a back-side anti-reflective coating. In another embodiment that can be combined with other embodiments described herein, the photoresist may include silicon actinide (SiAc) and an optical planarization layer. The barrier layer 501 allows for the use of a single stencil in a single nanoimprinting step of operation 402.

[0038] In operation 405, as shown in Figure 5C, a barrier layer 501 is disposed on the first resist portion 111 of the first resist layer 105. The barrier layer 501 covers the first resist portion 111, while a second resist portion 112 of the resist layer 105 is etched in operation 406.

[0039] After the first resist layer 105 is etched, the barrier layer 501 is removed in operation 407, allowing the optical element substrate 101 to be further processed. As shown in Figure 5D, the first hard mask portion 311 and the second hard mask portion 312 of the hard mask 103 are etched by one or more of ion beam etching or electron beam etching. Using a resist structure 106 patterned in the first resist layer 105, the hard mask 103 is patterned and etched through openings in the patterned first resist layer 105. The patterned hard mask 103 corresponds to a pattern imprinted in the resist layer 105 by a mold 301.

[0040] After the hard mask 103 is etched, the optical element substrate 101 undergoes further processing to form a plurality of optical element structures 320. In one embodiment, as shown in Figure 5D, element material 102 is etched through the hard mask 103 to form a plurality of optical element structures 320 on the optical element substrate 101 from element material 102. In another embodiment, which can be combined with other embodiments described herein, the plurality of optical element structures 320 are formed by etching the optical element substrate 101. A first resist portion 111 of the first resist layer 105 corresponds to a first optical element structure 330, and a second resist portion 112 of the first resist layer 105 corresponds to a second optical element structure 340. The first optical element structure 330 has a first operating cycle, and the second optical element structure 340 has a second operating cycle different from the first operating cycle. A single-height mold 301 is a negative pattern of the plurality of optical element structures 320.

[0041] In summary, the overall processing uniformity is improved by using the nanoimprint lithography and etching process described herein to form optical components. By etching regions with different operating cycles separately, over-etching due to variations in the thickness of the residual layer is reduced, thereby improving the resolution of the resist structure and subsequently the structure of the optical component. Furthermore, processing efficiency is improved through the use of a single-height mold.

[0042] While the foregoing describes embodiments of the present invention, other and further embodiments of the present invention may be conceived without departing from the basic scope of the present invention, and the scope of the present invention is determined by the following claims.

[0043] 100: Part of the optical element substrate 101: Optical component substrate 102: Component Materials 103: Hard Mask 104: First wetting layer 105: First inhibitor layer 106: Inhibitor Structure 111: First inhibitor section 112: Second inhibitor section 120: First Residual Layer 121: Thickness 122: Second Residual Layer 123: Thickness 130: Spacing 132: Altitude 140: Critical Size 200: Method 201,202,203,204,205,206,207,208: Operations 301: Imprint 302: Features 303: Second Imprint 304: Second wetting layer 305: Second inhibitor layer 311: First Hard Mask Part 312: Second hard mask section 320: Optical Element Structure 330: Structure of the first optical element 340: Second optical element structure 400: Method 401, 402, 403, 404, 405, 406, 407: Operations 501: Barrier Layer

[0044] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A method of forming an optical element, comprising the steps of: depositing a first resist layer on a substrate having a hard mask disposed above an element material, the element material being disposed beneath an entire area of ​​the hard mask; imprinting a first resist portion of the first resist layer with a first single-height mold having a first operating cycle, the first operating cycle corresponding to a first operating cycle of a first optical element structure of the optical element to be formed; etching the first resist portion of the first resist layer; etching a first hard mask portion of the hard mask corresponding to the first resist portion of the first resist layer; removing the first resist layer and depositing a second resist layer; imprinting a second resist portion of the second resist layer with a second single-height mold having a second operating cycle, the second operating cycle corresponding to a second operating cycle of a second optical element structure of the optical element to be formed; etching the second resist portion of the second resist layer; Etching a second hard mask portion of the hard mask corresponding to the second resist portion of the second resist layer; and etching the element material to form an optical element having a first portion, a second portion, and an intermediate portion between the first portion and the second portion, the first portion having a first optical element structure with the first operating cycle, and the second portion having a second optical element structure with the second operating cycle, the second operating cycle being different from the first operating cycle.

2. The method as described in claim 1, wherein the first single-height imprint is a negative pattern of the first optical element structure.

3. The method as described in claim 1, wherein the second single-height imprint is a negative pattern of the second optical element structure.

4. The method as described in claim 1, wherein depositing the first resist layer comprises a spin-coating deposition process.

5. A method of forming an optical element, comprising the steps of: depositing a first resist layer on a substrate by spin coating deposition, the substrate having a hard mask disposed on the substrate and an element material disposed under an entire area of ​​the hard mask; imprinting a first resist portion of the first resist layer with a first single-height mold having a first operating cycle, the first operating cycle corresponding to a first operating cycle of a first optical element structure to be formed of the optical element, the first resist layer having a first residual layer thickness; etching the first resist portion of the first resist layer; etching a first hard mask portion of the hard mask corresponding to the first resist portion of the first resist layer; removing the first resist layer and depositing a second resist layer; imprinting a second resist portion of the second resist layer with a second single-height mold having a second operating cycle, the second operating cycle corresponding to a second operating cycle of a second optical element structure to be formed of the optical element, the second resist layer having a second residual layer thickness less than the first residual layer thickness; The process involves etching the second resist portion of the second resist layer; etching a second hard mask portion of the hard mask corresponding to the second resist portion of the second resist layer; and etching the element material to form an optical element having a first portion and a second portion, the first portion having a first optical element structure with the first operating cycle, and the second portion having a second optical element structure with the second operating cycle, the second operating cycle being different from the first operating cycle.

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