An apparatus of single substrate multi-electron beam lithography array and a method of fabrication thereof

Abstract

The present invention relates to a monolithically fabricated multi-electron beam lithography apparatus (100) integrated on a single substrate (101). The apparatus (100) comprises an array of field emission electron emitters, each formed with a nanoscale emitter tip (102a) and coated with a work function lowering coating (102b), electrically connected through an on-chip control architecture (103) for independent biasing and switching. A dielectric support structure (106) comprising dielectric support pillars (106a) provides mechanical and electrical isolation. An anode aperture array (108), aligned coaxially with the emitter tips (102a), is supported above the emitters and enables beam collimation. An electron optics array (110) incorporating coaxially stacked Einzel lens (112) is formed above the anode, focusing emitted beamlets without requiring individual lens tuning. A built-in deflector array (109) provides beam steering.

Description

[0001] AN APPARATUS OF SINGLE SUBSTRATE MULTI-ELECTRON BEAM LITHOGRAPHY ARRAY AND A METHOD OF FABRICATION THEREOF

[0002] FIELD

[0003] The present invention relates to semiconductor lithography, and more particularly to multi-beam, maskless electron-beam direct-write lithography systems. More specifically, it concerns an apparatus and method in which a field-emission cathode (emitter) array, an anode -aperture array, deflector array (optional) and an electrostatic lens array are monolithically fabricated in successive layers on a common substrate, thereby enabling generation and manipulation of multi electron beams for maskless, high-throughput, high resolution patterning.

[0004] DEFINTIONS

[0005] The term “substrate” used herein in the description refers to the base wafer or surface, typically a silicon wafer, on which nanostructures are fabricated.

[0006] The term “aperture” used herein in description refers to a nanoscale opening in the suspended conductive anode layer directly above the field emission tips to extract electrons, pre-collimate and define beam current for each electron beam, and block stray emissions prior to focusing by the integrated electrostatic lens array.

[0007] The term “sacrificial layer” used herein in description refers to a temporary material deposited during micro / nanofabrication to create voids, support, or suspended structures, which is later selectively removed.

[0008] The term “patterning” used herein in description refers to the process of creating a defined spatial arrangement of material or void by selectively exposing, developing, etching, depositing, or otherwise modifying a resist, polymer, or other medium, forming topographical or compositional features that correspond to the intended design, which may remain in the patterned layer or serve as a template for subsequent feature transfer to the fdm or the wafer.

[0009] The term “etching” used herein in description refers to a controlled removal of material from a substrate or film using chemical, plasma, ion-beam, or physical processes that dissolve or erode regions unprotected by a patterned resist over it; in either an isotropic or anisotropic manner to shape or form features .

[0010] The term “Atomic Layer Deposition (ALD)” used herein in description refers to a cyclic, surface-reaction-based vapor phase thin film deposition technique that builds up ultra-thin films one atomic layer at a time via sequential, self-limiting surface reactions for precise thickness and conformity.

[0011] BACKGROUND

[0012] The background information hereinbelow relates to the present disclosure but is not necessarily prior art.

[0013] Lithographic patterning is a critical process in semiconductor manufacturing and nanofabrication, facilitating the precise transfer of geometric patterns onto a substrate through selective material deposition or etching. Conventional photomask-based optical lithography, employing ultraviolet sources such as i-line (365 nm), KrF (248 nm), and ArF (193 nm), has achieved feature sizes as small as approximately 38 nm. The advent of extreme-ultraviolet (EUV) lithography, utilizing 13.5 nm wavelengths and high-numerical-aperture optics (up to NA 0.55), has further reduced this threshold to approximately 8 nm. Despite these advancements, EUV systems demand complex infrastructure, including high- intensity light sources, multilayer reflective optics, and defect-free photomasks, resulting in equipment costs exceeding US $350 million per unit and substantial operational overhead. These factors render EUV lithography impractical for low- volume production or rapid prototyping applications. As an alternative, single-beam electron-beam lithography (EBL) has been utilized to achieve sub-5 nm resolution without reliance on photomasks. In EBL, a focused electron beam, generated by a high-brightness field-emission gun and directed through aberration-corrected lenses, exposes an electron-sensitive resist with exceptional precision. While this maskless approach offers significant flexibility for research and small-scale fabrication, its serial writing mechanism restricts throughput to a few wafers per hour, limiting its viability for high- volume manufacturing.

[0014] To address these throughput constraints, multi-electron-beam lithography (MEBL) systems have been developed, building on concepts introduced in the 1980s and refined by subsequent innovations. MEBL utilizes arrays of hundreds to thousands of electron-beamlets, each with dedicated emitters, extraction apertures, focusing optics, and beam-blanking or deflection mechanisms to achieve enhanced patterning efficiency, making it suitable for advanced applications such as optical mask writing and lithography.

[0015] Despite its promise, conventional MEBL systems face significant technical limitations. Chief among these are issues of reduced resolution and reduced beam current compared to an EBL system, due to limited extraction field strength, lower-NA electrostatic optics, a larger virtual source, and charge space effects. These factors degrade beam quality, limit achievable feature sizes, and lead to non-uniform beamlet behavior, ultimately reducing system performance and throughput.

[0016] In addition, conventional MEBL architectures often require a large common condenser lens for crossover of beamlets, which increases the system’s power demands. The inclusion of multiple dynamic components, such as beam blankers and astigmatism correctors, further escalates fabrication complexity, integration complexity, and alignment overhead.

[0017] Several approaches in the prior art have attempted to address aspects of the MEBL system design. For example: Chinese patent CN112485980 A proposes a laser-triggered multi -electron beam array device, but lacks integration of focusing optics such as Einzel lenses or provisions for enhancing beamlet current.

[0018] European patent ES2141674 Bl discloses microlens arrays fabricated using microelectronics techniques but does not address high-resolution beam control or system throughput improvements.

[0019] Japanese patent JP4150363 B2 introduces deflector-based correction systems and complex multi-lens arrangements, but still relies on conventional condenser lens architectures.

[0020] In US6919952 B2, an array of individual emitters and projection optics writes demagnified pattern segments in parallel, though lens aberrations in closely spaced beamlets were reported. Patent WO 98 / 48443 proposes dense cathode arrays but warns of aberration in conventional lenses, while US4394789 A envisages a 3 x 3 array of 16 x 16 micro columns to expose multiple dies concurrently. More recent multicolumn platforms (Multi-beam) employ hundreds of miniaturized e-beam columns to pattern sub-50 nm features on full wafers, yet fabricate emitters, apertures and lenses on separate substrates assembled by flip- chip bonding and active alignment, thereby introducing inter-column registration errors and limiting extraction field strength and field strength of the electrostatic / condenser lens array.

[0021] Other cited documents, such as JP2022035477A, US4694178A, EP12190692A, and US5945677A, describe various multi-beam systems, blanking methods, and projection optics but fail to solve key MEBL limitations, particularly related to beamlet current enhancement and resolution scaling.

[0022] Moreover, prior art systems often rely on separate modules, increasing mechanical complexity and alignment overhead. Therefore, there is a need long-felt need for a new MEBL architecture that provides high resolution along with high throughput while reducing system complexity. By monolithically integrating the emitter array, aperture array, deflector array (optional) and electrostatic / Einzel lens array by fabricating them in successive layers on a single substrate, the present invention reduces space charge effects, increases beamlet current, achieves sub-5 nm resolution, and is scalable, efficient, and suitable for industrial implementation. OBJECTS OF THE PRESENT DISCLOSURE

[0023] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

[0024] An object of the present invention is to provide an apparatus comprising a singlesubstrate multi-electron beam lithography array and a method of fabrication thereof.

[0025] Another object of the present invention is to provide an apparatus and fabrication process that addresses the resolution limitations of conventional multi-electron beam lithography systems.

[0026] Still another object of the present invention is to provide an apparatus and fabrication process that achieves higher beamlet currents at the same operating voltages when compared to existing MEBL architectures.

[0027] Still another object of the present invention is to provide an element of the apparatus and fabrication method in which a monolithically fabricated Einzel lens array replaces conventional condenser lens systems or single-column electron optics to eliminate crossover of beams and minimize beam-to-beam interaction by reducing the beam paths.

[0028] Still another object of the present invention is to provide a monolithically fabricated hollow column-in-strata Einzel / electrostatic lens array, in which concentric lens electrodes are formed in vertically stacked conductor-insulator strata on a single substrate, replacing multi multi-substrate stacked electrostatic lens arrangement and enabling high-numerical-aperture beam collimation with superior optical fidelity.

[0029] Still another object of the present invention is to provide a deflector array, cofabricated either upstream or downstream of the electrostatic lens array, comprising individually addressable electrostatic deflection elements for real-time beam steering.

[0030] Still another object of the present invention is to provide a monolithically fabricated, energy-efficient multi-electron beam system that simplifies architecture, reduces power consumption, and lowers overall production cost.

[0031] Still another object of the present invention is to enable the fabrication of independently controllable field emission-based micro electron beam sources within a compact and integrated design.

[0032] Still another object of the present invention is to enable dynamic ON / OFF switching of electron beamlets through a control architecture, thereby improving operational precision and reducing patterning errors.

[0033] Still another object of the present invention is to provide a structurally robust and stable emitter system capable of long-term operation without degradation.

[0034] Still another object of the present invention is to provide an element of the apparatus in which the apertures of each emitter in the field emitter array are fabricated into a suspended extraction anode over the emitter tips instead of being on the sidewalls reducing electron dispersion, beam divergence and enhancing extraction field strength, thereby increasing emission current density. .

[0035] Still another object of the present invention is to eliminate the need for beam axis alignment coils, beam blankers, and astigmatism correctors, thereby simplifying system complexity while maintaining beam integrity. Still another object of the present invention is to overcome the inherent drawbacks of prior multi-electron beam lithography technologies through a novel, vertically integrated substrate design with optimized electrostatic focusing and simpler beam control.

[0036] Still another object of the present invention is to provide a scalable parallel-beam architecture, in which increasing the array size boosts throughput without adding alignment or much control complexity.

[0037] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

[0038] SUMMARY

[0039] This summary is provided to introduce concepts related to a single-substrate multi-electron beam lithography (MEBL) apparatus. These concepts are further described in detail in the subsequent specification. This summary is not intended to identify essential features of the claimed invention, nor is it intended to limit the scope of the claimed subject matter.

[0040] Various embodiments of the present invention relate to an apparatus and method for fabricating a lithography system that utilizes a grid-arranged array of electron beamlets generated from field emission sources fabricated onto a common substrate. The invention enables scalable, precise, and energy-efficient electron beam generation and control using a monolithic fabricated configuration of emitters, apertures, deflection, and electrostatic focusing optics.

[0041] In an embodiment, the apparatus comprises a substrate on which a control architecture is formed to provide electrical interconnections and independent biasing for a plurality of field emission electron emitters. Each emitter comprises a tip fabricated via etching and coated with a work function-lowering material to facilitate efficient electron emission. A dielectric support structure is formed around the emitters, comprising a plurality of support pillars configured to isolate and suspend an anode aperture array over the emitter array. The aperture array includes a plurality of apertures aligned with corresponding emitters to allow the extraction of multiple parallel electron beamlets.

[0042] Above the aperture array, an electron optics array is fabricated, which includes a plurality of Einzel lenses. Each Einzel lens is fabricated by etching through a sequence of alternating conductive and insulating layers to form a hollow column- in-strata configuration. The lenses are coaxially aligned with the corresponding emitter-aperture pairs, and each lens electrode in a said layer is connected to neighbouring lens electrodes such that all lens electrodes in the said layer achieve equi-potential to maintain uniform focusing of all beamlets without requiring individual lens tuning.

[0043] Moreover, in certain embodiments, the apparatus may further include an optional deflector array disposed either above or below the lens array, particularly in systems in which the apparatus is configured without a short stroke stage movement along one or both horizontal axes. The deflector array comprises a shielding layer and a plurality of pairs of deflector electrodes for each electronoptics column. The deflector electrodes are independently biased to establish localized electric fields within each column, thereby steering individual beamlets as required, while the interposed shielding layer confines these fields to prevent interference with the electrostatic lenses or with other deflectors located in layers above or below, thus preserving beam fidelity.

[0044] The apparatus further features an m x n grid-like layout for the emitters, apertures, and lenses, enabling systematic pattern generation. The electrodes within the Einzel lenses may assume various cross-sections — circular, elliptical, rectangular, or polygonal — depending on the desired beam focusing parameters for specific lithographic applications. The apparatus provides for dynamic emitter control through the control architecture, allowing each emitter to be independently switched ON or OFF based on lithography pattern data, eliminating the need for beam blankers. The monolithic integration of all functional layers — including emitters, apertures, and optics — minimizes misalignment of the different elements of the apparatus and eliminates the need for beam axis alignment coils and astigmatism correction systems.

[0045] The invention also includes a fabrication process wherein all structural components are deposited and patterned sequentially on the same substrate, utilizing standard microfabrication techniques, material suspension / isolation strategies, and sacrificial layer etching methods to form the suspended aperture structures.

[0046] Overall, the disclosed invention presents a compact, scalable, and high-resolution MEBL solution suitable for advanced semiconductor lithography and nanoscale patterning, while reducing power consumption, improving beam uniformity, and simplifying the optical column design.

[0047] The present disclosure also envisages a method of fabricating an apparatus comprising a single-substrate multi-electron beam lithography array. The method includes steps such as:

[0048] • forming a control architecture on a substrate to provide electrical interconnections to emitter sites;

[0049] • depositing a dielectric material and forming a plurality of support pillars surrounding the sites at which the emitter tips will be fabricated;

[0050] • depositing an emitter material onto the substrate;

[0051] • patterning and etching the emitter material to form an array of emitter tip structures;

[0052] • depositing a work function-lowering coating onto the tip of each emitter;

[0053] • depositing a sacrificial fill material to occupy the cavities defined by the emitter tips and the inter-pillar regions, and subsequently performing chemical-mechanical planarization to achieve a coplanar surface across the pillars and fill material;

[0054] • blanket depositing a conductive material above the dielectric support structure;

[0055] • patterning and etching the conductive material to form an anode aperture array, each aperture being aligned with an underlying emitter tip;

[0056] • depositing alternating layers of conductive and insulating materials above the anode aperture array;

[0057] • etching the alternating layers to form concentric hollow-column Einzel lens structures, each lens coaxially aligned with a corresponding emitteraperture pair;

[0058] • removing sacrificial layers to release the levitated anode aperture structure, maintaining mechanical and electrical isolation between the emitters and the anode apertures;

[0059] • patterning, back-etching, and filling substrate vias with conductive material to form external contact pads for biasing the emitters, anode, and lenses, and deflectors, if present; and

[0060] • optionally, selectively etching the insulating layers using inductively coupled plasma reactive ion etching (ICP RIE) to create controlled concavities between adjacent electrode layers, thereby reducing electric field degradation due to charge accumulation on the insulating interfaces.

[0061] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawing and the following detailed description.

[0062] BRIEF DESCRIPTION OF THE DRAWING

[0063] An apparatus of single substrate multi-electron beam lithography array and a method of fabrication thereof, of the present disclosure, will now be described with the help of the accompanying drawing, in which: Figure 1 illustrates a schematic functional diagram of conventional multi-electron beam lithography systems, in accordance with an embodiment of the present disclosure;

[0064] Figure 2 illustrates a 3-dimensional vertical cross-sectional schematic representation of the fabricated structure of the apparatus of a single-substrate multi-electron-beam lithography array, in accordance with an embodiment of the present disclosure;

[0065] Figure 3 illustrates a 2-dimensional vertical cross-sectional schematic representation of the integrated emission and 3-electrode electron optics array multi-electron beam writing module of a single-substrate multi-electron-beam lithography array, in accordance with an embodiment of the present disclosure;

[0066] Figure 4 illustrates a 2-dimensional vertical cross-sectional schematic representation of the static integrated emission and 2-electrode electron optics array multi-electron beam writing module of a single-substrate multi-electronbeam lithography array, in accordance with an embodiment of the present disclosure;

[0067] Figure 5 illustrates an alternate exemplary flow diagram of a method of fabricating an apparatus comprising a single-substrate multi-electron beam lithography array, in accordance with an embodiment of the present disclosure;

[0068] Figures 6-8 illustrate an exemplary flow diagram of a method of fabricating an apparatus comprising a single-substrate multi-electron beam lithography array, in accordance with an embodiment of the present disclosure;

[0069] Figure 9 illustrates a graph of IV characterization results: total emitter current from 400 beams of a single-substrate multi-electron-beam lithography array, wherein the anode was maintained at 100 V and the cathode voltage was swept from 0 to -100 V, in accordance with an embodiment of the present disclosure;

[0070] Figure 10 illustrates a simulation result of a Nano-fabricated 3-electrode electrostatic lens biased at 6 kV of a single-substrate multi-electron-beam lithography array, in accordance with an embodiment of the present disclosure; and

[0071] Figure 11 illustrates a simulation result of a Nano-fabricated 2-electrode electrostatic lens biased at 8.5 kV of a single-substrate multi-electron-beam lithography array, in accordance with an embodiment of the present disclosure.

[0072] LIST OF REFERENCE NUMERALS

[0073] DETAILED DESCRIPTION

[0074] Embodiments of the present disclosure will now be described with reference to the accompanying drawing.

[0075] Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0076] The terminology used in the present disclosure, is only for the purpose of explaining a particular embodiment, and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and / or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

[0077] When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected, or coupled to the other element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0078] The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure, as the aforementioned terms may be used only to distinguish one element, component, region, layer, or section from another component, region, layer, or section. Terms such as first, second, third, etc., when used herein, do not imply a specific sequence or order unless clearly suggested by the present disclosure.

[0079] Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like may be used in the present disclosure to describe relationships between different elements as depicted in the figures.

[0080] The present disclosure relates to a multi-electron beam lithography apparatus, and more particularly, to a monolithically fabricated, single-substrate multi-electron beam lithography array comprising integrated emitter, aperture, deflection (optional) and focusing components with a high degree of alignment precision, beamlet control, and energy efficiency; high resolution; high throughput; and reduced aberrations.

[0081] In advanced lithography applications, there is a growing demand for a new MEBL architecture that provides high resolution along with high throughput while reducing system complexity. Traditional multi-electron beam lithography (MEBL) systems often suffer from reduced resolution and reduced beam current compared to an EBL system, due to limited extraction field strength, lower-NA electrostatic optics, a larger virtual source, and charge space effects. Furthermore, beam crossovers and misalignment of the different arrays used in the generation and control of beams add further aberrations to the beams.

[0082] The present disclosure addresses these limitations by providing a monolithic multi-electron beam lithography array (100), in which all primary electron -optical elements — namely, a field-emission emitter array, a suspended anode aperture array (108), and an electron optics array (110) are sequentially fabricated in successive layers on a common substrate (101). In certain embodiments, a monolithically integrated beam deflector array (109) is additionally incorporated. By defining all component geometries and relative positions via lithographic patterning, nanometer-scale alignment of the arrays is achieved inherently, thereby obviating the need for aberration / distortion correction mechanisms..

[0083] An apparatus (100) of a single-substrate multi -electron beam lithography array will now be described with reference to Figures 1 to 4, and Figures 9 to 11, and a method (200) of fabricating the same is described with reference to Figures 5 to 8.

[0084] As illustrated in Figure 1, a schematic functional diagram of a conventional multi-electron beam lithography system is shown for comparative understanding. Figure 2 illustrates a schematic representation of the fabricated structure of the disclosed apparatus (100), including substrate (101), emitters, and stacked components. The substrate (101) serves as the base for integrated electronics and structural support.

[0085] A control architecture (103) is fabricated on the substrate (101) which consists of its device layer, connections and bias providing independent electrical connections to each emitter and electrode in the array, as shown in Figure 3, and is configured to enable individual switching of emitters by modulating the emitter bias voltage via contact pads on the back or edges of the substrate (101) allow external wiring to bias the emitters, anode, lenses, and deflectors (if present). Each field emission electron emitter includes a nanometer-scale emitter tip (102a), formed by isotropic etching of a metallic or semiconducting material. A work function-lowering coating (102b) is deposited onto each tip to improve emission efficiency. The work function lowering coating (102b) comprises a material selected from barium oxide (BaO), zirconium oxide (ZrO2). or strontium oxide (SrO), and has a thickness between 1 nanometer and 2 nanometers.

[0086] The emitters are surrounded by dielectric support pillars (106a) which provide electrical isolation and structural integrity. The dielectric support pillars (106a) comprise a material selected from the group consisting of silicon dioxide (Si Oz). Hafnium oxide (HfCh). Hexagonal boron nitride (h-BN), Aluminium Nitride (AIN), zirconium dioxide (ZrO2). or any other suitable dielectric. These pillars are configured to support an anode aperture array (108) above the emitter layer, with each aperture (108a) precisely aligned with the underlying emitter tip (102a), as depicted in Figures 3 through 4. By applying a high positive voltage to the anode relative to the emitters, electrons are extracted into free space, and each beamlet is roughly collimated by the aperture geometry. The suspended nature of the anode creates a stronger extraction field for field emission. The emitter array, anode aperture array (108), and electron optics array (110) are arranged in a two- dimensional grid structure having m rows and n columns, wherein m and n are integers greater than one. The arrangement of apertures (108a) and the emitters follows a rectangular or square matrix pattern.

[0087] Above the aperture array (108), an electron optics array (110) is formed, comprising multiple Einzel lenses (112). Each Einzel lens (112) includes multiple conductive electrode layers (112a) and insulating layers (112b) deposited sequentially and etched to form concentric hollow columns-in-strata. These lenses are configured to focus the emitted electron beamlets with high axial precision. The conductive electrode layers (112a) of the Einzel lenses (112) are commonly biased relative to the emitters and apertures (108a) through a unified voltage supply to maintain focusing uniformity across all beamlets.

[0088] In an embodiment, the Einzel lenses (112) are implemented as a densely packed two-dimensional configuration of miniature electrostatic lenses, each typically composed of three concentric electrode layers fabricated directly on-chip. These lenses are constructed by sequentially depositing and etching alternating conductive electrode layers (112a) and insulating layers (112b) to create coaxial cylindrical cavities precisely aligned above each corresponding emitter. This monolithic fabrication ensures uniformity in alignment, electrode spacing, and optical axis across the entire array, eliminating the need for individual mechanical assembly, alignment, or wiring. Unlike conventional Einzel lenses — assembled from discrete components and requiring meticulous alignment and multiple high- voltage feeds — the integrated lens array employs a common fabrication process and a unified biasing scheme. This results in sub-micron inter-electrode spacing, enhanced electrostatic focusing fields, increased beam current density, and significantly reduced lens aberrations.

[0089] In an embodiment, the shape of the conductive electrode layers (112a) in the Einzel lens (112) is selected from circular, elliptical, rectangular, or polygonal cross-sectional profiles, depending on desired beam focusing properties. The electrode cross-sectional shape is chosen to optimize focusing for specific electron beam energy ranges or patterning requirements.

[0090] In some embodiments, the apparatus (100) includes a deflector array (109). The deflector array (109) may be placed directly above the anode but below the lenses, or above the lenses, depending on design. Each deflector unit for a beam column consists of two parallel electrodes facing each other, with a shielding layer (109b) between the deflector array and the lens array. By biasing the pair of deflector electrodes with equal and opposite voltages, a transverse electric field is applied to deflect that beamlet. The shielding layer (109b) confines the deflection field, preventing alteration of the field induced by the lens for beam collimation.

[0091] Figure 4 provides an alternate 2-dimensional vertical cross-sectional schematic view of the integrated emission and optics array module, illustrating the consistent alignment and fabrication of the emitter-aperture-lens axis throughout the system.

[0092] Figure 5 illustrates an alternate exemplary flow diagram of a method (200) of fabricating an apparatus (100) comprising a single-substrate multi-electron beam lithography array, in accordance with an embodiment of the present disclosure. The method (200) for fabricating the multi-electron beam lithography array will now be described with reference to Figures 6 to 8. As illustrated in Figure 5 and Figures 6 to 8, the method (200) comprises the following steps:

[0093] • forming (202) a control architecture (103) on a substrate (101) to provide electrical interconnections to emitter sites;

[0094] • depositing (204) a dielectric material and forming a plurality of support pillars (106a) surrounding the sites at which the emitter tips (102a) will be fabricated;

[0095] • depositing (206) an emitter material onto the substrate (101);

[0096] • patterning and etching (208) the emitter material to form an array of emitter tips (102a);

[0097] • depositing (210) a work function lowering coating (102b) onto each emitter tip (102a);

[0098] • depositing (212) a sacrificial fill material (107) to occupy the cavities defined by the emitter tips and the inter-pillar regions, and subsequently performing chemical-mechanical planarization to achieve a coplanar surface across the pillars (106a) and fill material;

[0099] • blanket depositing (214) a conductive material above the dielectric support structure (106);

[0100] • patterning and etching (216) the conductive material to form an anode aperture array (108), each aperture (108a) being aligned with an underlying emitter tip (102a);

[0101] • depositing (218) alternating conductive electrode layers (112a) and insulating layers (112b) above the anode aperture array (108);

[0102] • etching (220) the alternating layers to form concentric hollow-column Einzel lens (112), each Einzel lens (112) coaxially aligned with a corresponding emitter-aperture pair (102a, 108a);

[0103] • removing (222) sacrificial material layers (107) to release the levitated anode aperture structure (108), maintaining mechanical and electrical isolation between the emitters and the anode apertures (108a); • paterning, back-etching, and filling (224) substrate vias with conductive material to form external contact pads for biasing the emiters, the anode aperture array (108), the Einzel lens (112), and the deflectors (109a), if present; and

[0104] • optionally, selectively etching (226) the insulating layers (112b) using inductively coupled plasma reactive ion etching (ICP RIE) to create controlled concavities between adjacent conductive electrode layers (112a), thereby reducing electric field degradation due to charge accumulation on the insulating interfaces.

[0105] In an embodiment, the emiter material is selected from tungsten, molybdenum, or any other suitable element or compound.

[0106] In an embodiment, the dielectric support pillars (106a) are formed by paterning and etching a deposited SiCE, HfCE, or h-BN layer.

[0107] In an embodiment, the work function lowering coating (102b) is deposited by atomic layer deposition (ALD) or evaporation techniques.

[0108] In an embodiment, each Einzel lens (112) is formed by etching through the alternating conductive electrode layers (112a) and insulating layers (112b).

[0109] In an embodiment, the sacrificial layer is accessed through the side channels and selectively removed by appropriate chemicals.

[0110] Figure 9 illustrates the measured emission performance of 400 beams from the fabricated field emiter array under a proof-of-concept setup. The array, comprising multiple nanoscale emiters, was tested for beam current output.

[0111] Each emiter in the array produced a beam current of approximately 180 nA, with the emission directed through an aperture, corresponding to 74 pA for 400 beams. This corresponds to a current density of approximately 2291.83 A / cm2, indicating the system's capability to achieve high beam intensity at nanoscale dimensions.

[0112] A standard 300 mm wafer offers approximately 706 cm2of usable surface area, accommodating around 62 dies of typical dimensions 26 mm x 33 mm. To fully expose this surface using electron-beam lithography, a dose of approximately 200pC / cm2is required at the wafer level. For a target throughput of 200 wafers per hour, this translates to a cumulative charge requirement of roughly 28 C / hr. Achieving this charge rate necessitates a continuous beam current of approximately 8 mA. Based on experimentally verified performance, each beam can deliver a stable current of approximately 180 nA, as shown in Figure 9. At this performance level, a parallel array of 44,000 beamlets is sufficient to meet the total beam current requirement, thereby achieving the desired throughput

[0113] This validates the invention's suitability for massively parallel direct-write lithography, combining high resolution, high current density, and manufacturable throughput without the need for traditional optical column assemblies or beam blankers.

[0114] The design enables a large array of beams to operate in parallel with uniform characteristics. By building everything on one substrate (101), space-charge effects are reduced, and beam currents per column are higher than in split architectures. This facilitates writing large area patterns quickly while preserving sub- 10 nm (even sub-5 nm) resolution.

[0115] Simulation results shown in Figures 10 and 11 demonstrate the electric field profiles of 3 -electrode and 2-electrode electrostatic lens configurations, biased at 6 kV and 8.5 kV, respectively. Figures 10 and 11 present simulation results of the electron beam propagation and focusing performance of the proposed nanoscale electron emitter system, with emphasis on spot size and working distance optimization for high-resolution lithographic applications.

[0116] Figure 10 illustrates a simulated beam profile where the optimal spot size was determined to be approximately 1.5 nm when the system was operated at a working distance of 9.8 microns. This configuration balances the requirements of proximity focusing, lens aberration minimization, and current density control, yielding a tightly focused beam ideal for sub-2 nm patterning precision. Figure 11 demonstrates the simulated beam configuration for a larger, yet still sub- 10 nm, spot size regime. In this scenario, a spot size of 5 nm was achieved at an increased working distance of 20.7 microns. This longer working distance may be preferred in scenarios requiring increased clearance between the emitter tip and the resist surface or when integrating with additional optical or electrostatic beam steering mechanisms.

[0117] In both simulation cases, the system demonstrated a Depth of Focus (DOF) on the order of hundreds of nanometers, which is significantly greater than the ~50 nm DOF typically associated with Extreme Ultraviolet Lithography (EUVL). This extended DOF provides considerable process flexibility and robustness, reducing sensitivity to resist topography variations and substrate flatness, thereby enhancing manufacturability.

[0118] These simulation results validate the system's capacity to support high-resolution patterning with precise beam confinement and depth control across a practical working range. They further underscore the advantage of the disclosed architecture in enabling direct-write nanolithography with resolution and process windows competitive with, or superior to, advanced projection lithography techniques, while eliminating the need for complex projection optics or photomasks. These results validate uniform focusing behavior and low beam divergence.

[0119] The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

[0120] TECHNICAL ADVANCEMENT The present disclosure described hereinabove has several technical advantages, including, but not limited to, an apparatus of a single substrate multi-electron beam lithography array and a method of fabrication thereof, that;

[0121] • addresses the resolution limitations of conventional multi-electron beam lithography systems;

[0122] • achieves higher beamlet currents at the same operating voltages when compared to existing MEBL models;

[0123] • minimizes data path burden and reduces computational requirements;

[0124] • enables precise focusing and control of individual electron beamlets;

[0125] • simplifies architecture, reduces power consumption, and lowers overall production cost;

[0126] • reduces the footprint of the lithography system by compactifying the writing apparatus;

[0127] • the compact design allows hot swapping of the writing apparatus; and

[0128] • eliminates the need for beam axis alignment coils, beam blankers, astigmatism correctors, or beam crossovers in the system architecture, thereby simplifying system complexity while maintaining beam integrity.

[0129] The foregoing disclosure has been described with reference to the accompanying embodiments, which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

[0130] The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as not to unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0131] The foregoing description of the specific embodiments so fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[0132] Any discussion of devices, articles, or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0133] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment, as well as other embodiments of the disclosure, will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:1 An apparatus (100) comprising a single-substrate multi-electron beam lithography array, the apparatus (100) comprising:• a substrate (101);• a control architecture (103) formed on the substrate (101) and configured to provide electrical interconnections and independent biasing to a plurality of emitter sites;• an array of field emission electron emitters formed on the substrate (101), each emitter comprising: o an emitter tip (102a) fabricated by isotropic etching of a field emitter material; and o a work function lowering coating (102b) material applied to the emitter tip (102a);• a dielectric support structure (106) comprising a plurality of dielectric support pillars (106a) extending upward from the substrate (101) and surrounding each emitter, wherein the dielectric support structure (106) mechanically and electrically isolates the emitters from the anode;• an anode aperture array (108) positioned above the emitter array and supported by the dielectric pillars (106a), the anode aperture array (108) comprising a plurality of apertures (108a), each aperture (108a) being coaxially aligned with a corresponding emitter tip (102a);• an electron optics array (110) disposed above the anode aperture array (108), the electron optics array (110) comprising: o a plurality of Einzel lenses (112), each Einzel lens (112) fabricated by etching through sequentially deposited alternating conductive electrode layers (112a) and insulating layers (112b); o wherein each Einzel lens (112) is coaxially aligned with the corresponding emitter tip (102a) and aperture (108a); and• a unified voltage supply electrically connected to the conductive electrode layers (112a) of the Einzel lenses (112), configured to focus the emitted electron beamlets without individual electrode voltage adjustment; wherein the substrate (101), the emitter array, the dielectric support structures (106), the anode aperture array (108), and the electron optics array (110) are fabricatedmonolithically as an integrated structure with fixed relative alignment among corresponding emitters, the apertures (108a), and the Einzel lenses (112), thereby minimizing beamlet misalignment and eliminating the need for beam blankers, alignment coils, and astigmatism correctors.2 The apparatus (100) as claimed in claim 1, further comprising a deflector array (109) fabricated either above or below said electron-optics array (110), said deflector array comprising, for each beam column:• a pair of electrostatic deflectors (109a) configured to induce a transverse electric field for steering individual beams;• a shielding layer (109b) that confines the deflection field to the region between the deflection electrodes and prevents interference with the Einzel lens (112) or other deflectors (109a) in layers above or below.3 The apparatus (100) as claimed in claim 1, wherein the work function lowering coating (102b) comprises a material selected from barium oxide (BaO), zirconium oxide (ZrCE). or strontium oxide (SrO), and has a thickness between 1 nanometer and 2 nanometers.4 The apparatus (100) as claimed in claim 1, wherein the dielectric support pillars (106a) comprise a material selected from the group consisting of silicon dioxide (SiCE), Hafnium oxide (HfCE), Hexagonal boron nitride (h-BN), Aluminium Nitride (AIN), zirconium dioxide (ZrCE), or any other suitable dielectric material.5 The apparatus (100) as claimed in claim 1, wherein each Einzel lens (112) comprises two or more coaxial conductive electrode layers (112a) separated by insulating layers (112b).6 The apparatus (100) as claimed in claim 1, wherein the conductive electrode layers (112a) of the Einzel lens (112) are commonly biased relative to the emitters and apertures (108a) through a unified voltage supply to maintain focusing uniformity across all beamlets.7 The apparatus (100) as claimed in claim 1, wherein the control architecture (103) is configured to enable individual switching of emitters by modulating the emitter bias voltage.The apparatus (100) as claimed in claim 1, wherein the emitter array, anode aperture array (108), and electron optics array (110) are arranged in a two-dimensional grid structure having m rows and n columns, wherein m and n are integers greater than one. The apparatus (100) as claimed in claim 1, wherein the arrangement of apertures (108a) and emitters follows a rectangular or square matrix pattern. The apparatus (100) as claimed in claim 1, wherein the shape of the conductive electrode layers (112a) in the Einzel lens (112) is selected from circular, elliptical, rectangular, or polygonal cross-section profdes, depending on desired beam focusing properties. The apparatus (100) as claimed in claim 1, wherein the electrode cross-sections is chosen to optimize focusing for specific electron beam energy ranges or patterning requirements. A method (200) of fabricating an apparatus (100) comprising a single-substrate multielectron beam lithography array, the method (200) comprising:• forming (202) a control architecture (103) on a substrate (101) to provide electrical interconnections to emitter sites;• depositing (204) a dielectric material and forming a plurality of dielectric support pillars (106a) surrounding the sites at which the emitter tips (102a) will be fabricated;• depositing (206) an emitter material onto the substrate (101);• patterning and etching (208) the emitter material to form an array of emitter tips (102a);• depositing (210) a work function lowering coating (102b) onto each emitter tip (102a);• depositing (212) a sacrificial fill material (107) to occupy the cavities defined by the emitter tips and the inter-pillar regions, and subsequently performing chemicalmechanical planarization to achieve a coplanar surface across the dielectric support pillars (106a) and fill material;• blanket depositing (214) a conductive material above the dielectric support pillars (106a);• patterning and etching (216) the conductive material to form an anode aperture array (108), each aperture (108a) being aligned with an underlying emitter tip (102a);• depositing (218) alternating conductive electrode layers (112a) and insulating layers (112b) materials above the anode aperture array (108);• etching (220) the alternating layers to form concentric hollow-column Einzel lens (112), each Einzel lens (112) coaxially aligned with a corresponding emitter-aperture pair (102a, 108a);• removing (222) sacrificial layers to release the levitated anode aperture structure (108), maintaining mechanical and electrical isolation between the emitters and the anode apertures (108a);• patterning, back-etching, and filling (224) substrate vias with conductive material to form external contact pads for biasing the emitters, the anode aperture array (108), and the Einzel lens (112), and the deflectors (109a), if present; and• optionally, selectively (226) etching the insulating layers (112b) using inductively coupled plasma reactive ion etching (ICP RIE) to create controlled concavities between adjacent conductive electrode layers (112a), thereby reducing electric field degradation due to charge accumulation on the insulating interfaces. The method (200) as claimed in claim 12, wherein the emitter material is selected from tungsten, molybdenum, or any other suitable element or compound. The method (200) as claimed in claim 12, wherein the dielectric support pillars (106a) are formed by patterning and etching a deposited SiCE, HfCE. h-BN layer or any other suitable material. The method (200) as claimed in claim 12, wherein the work function lowering coating (102b) is deposited by atomic layer deposition (ALD) or evaporation techniques. The method (200) as claimed in claim 12, wherein each Einzel lens (112) is formed by etching through the alternating conductive electrode layers (112a) and insulating layers (112b). The method (200) as claimed in claim 12, wherein the sacrificial layer is accessed through side channels and selectively removed by appropriate chemicals. The method (200) as claimed in claim 12, wherein the emitter array, aperture array (108), and electron optics array (110) are patterned into a regular m*n grid during the lithographic patterning steps.The method (200) as claimed in claim 12, wherein the shape of the electrodes is determined during lithographic patterning to tailor beam divergence properties according to the application. The method (200) as claimed in claim 12, wherein the monolithic fabrication of the substrate (101), emitters, apertures (108a), and electron optics eliminates mechanical misalignment and enhances lithographic resolution of the emitted beamlets.

Images