Parallel electron beam imaging photoetching system based on micro electrostatic lens array and control method

Abstract

The invention discloses a parallel electron beam imaging photoetching system based on a micro electrostatic lens array and a control method, and aims to solve the technical problems that the existing electron beam photoetching efficiency is low, the system is complicated, and flexible zooming cannot be realized. The system sequentially comprises a unified electron source, a micro electrostatic lens array, an electron zooming focusing unit, a diaphragm plate and a vacuum sample table along the movement direction of an electron beam, and further comprises a driving circuit, the uniform electron source provides large-area uniform electron beams, the micro electrostatic lens array realizes on-off control of the electron beams through focusing / deflecting electrodes of each unit, the electronic zoom focusing unit adjusts imaging magnification through voltage ratio of multi-stage electrostatic electrodes, the diaphragm plate blocks the electron beams in an off state, and the driving circuit synchronously controls on-off and zoom magnification of the array. According to the invention, scanning-free and one-frame parallel exposure is realized, the imaging scaling can be flexibly adjusted, and the device has the advantages of high integration level, good stability, high exposure efficiency and strong adaptability, and can be used for high-end nano manufacturing scenes such as mask preparation, quantum devices, advanced packaging and the like.

Description

Technical Field

[0001] This invention belongs to the field of electron beam lithography and micro / nano fabrication technology, specifically relating to a system and control method for achieving scanless, variable magnification, parallel imaging electron beam exposure by using a unified electron source, combined with an addressable micro-electrostatic lens array and an electron scaling and focusing unit. Background Technology

[0002] Traditional single-beam electron beam lithography employs a point-by-point scanning method, resulting in low writing efficiency and making it difficult to meet the demands of large-scale nanostructure manufacturing. Existing multi-beam electron beam systems mostly utilize multi-electron source arrays or beam-splitting structures, which suffer from poor electron source uniformity, system complexity, high alignment difficulty, and low integration. Furthermore, traditional imaging-based electron beam optical systems are mostly fixed-magnification imaging systems, unable to flexibly adjust the pattern scaling ratio according to different processing scenarios, thus limiting their applicability. Summary of the Invention

[0003] Technical issues This invention addresses the following shortcomings of the prior art: The uniformity, stability, and lifespan of multi-electron source arrays are difficult to meet the requirements of mass production lithography. Traditional parallel electron beam systems are complex in structure and cannot achieve monolithic integration and CMOS-compatible driving; Existing electron beam imaging schemes are fixed magnification and lack scaling adjustment capabilities, making them unsuitable for the needs of multi-scale and multi-resolution nanofabrication. There is a lack of an imaging exposure scheme that can achieve electron beam switching solely through electric field control, requires no mechanical action, and can be scalably integrated.

[0004] Technical solution 1. System Structure A parallel electron beam imaging lithography system based on a micro-electrostatic lens array includes, in sequence along the direction of electron beam motion: a unified electron source, a micro-electrostatic lens array, an electron scaling and focusing unit, an aperture plate, a vacuum sample stage, and a driving circuit connected to the micro-electrostatic lens array and the electron scaling and focusing unit. A unified electron source is used to generate a continuous, large-area, high-brightness and uniformly distributed electron beam, which is used to irradiate the entire working surface of the micro-electrostatic lens array behind it. The micro-electrostatic lens array consists of multiple independent micro-electrostatic lens units arranged in a matrix. Each micro-electrostatic lens unit contains at least one set of focusing electrodes and one set of deflecting electrodes. The electrodes are mutually insulated and can be independently voltage-controlled. The micro-electrostatic lens array itself does not generate electrons; it is only used for electrically controlled switching and preliminary focusing control of the electron beam from a unified electron source: when a focusing voltage is applied to a micro-electrostatic lens unit, the unit is in a conducting state, and the electron beam is constrained and propagates axially; when a deflecting voltage is applied, the unit is in a deflecting state, and the electron beam is deflected to the outside of the array, unable to continue propagating axially. The electronic scaling and focusing unit consists of multiple levels of coaxial ring electrostatic electrodes, located between the micro electrostatic lens array and the aperture plate. By changing the voltage ratio of each level of electrodes, the imaging magnification of the electron beam can be continuously adjusted, thereby achieving magnification, reduction, or focusing adjustment of the electron beam, so that the electron beam transmitted by the conducting unit can ultimately form a nanometer-scale focused spot of the required size on the wafer surface. The aperture plate has light-transmitting holes at each unit position of the micro-electrostatic lens array, allowing only electron beams that are in the conducting state and propagating along the axis to pass through; when the electron beams are in the off state, they are deflected and absorbed in the non-aperture area of ​​the aperture plate, and cannot reach the wafer behind.

[0005] The vacuum sample stage is used to hold the wafer to be exposed and can achieve high-precision stepping movement to complete the stitching of multiple frames of images for large-area exposure. The driving circuit is used to synchronously output control signals to the micro-electrostatic lens array and the electronic scaling and focusing unit, control the conduction and cutoff of each micro-electrostatic lens unit according to the pattern to be exposed, and adjust the scaling factor of the electronic scaling and focusing unit according to the target resolution.

[0006] Control methods A parallel electron beam imaging lithography control method based on a micro-electrostatic lens array includes the following steps: S1. A unified electron source emits a stable and continuous electron beam to fully irradiate the micro-electrostatic lens array; S2. Based on the target size and resolution of the pattern to be exposed, the driving circuit configures the electrode voltages of each stage of the electron scaling and focusing unit to determine the required imaging scaling magnification; S3. The pattern to be exposed is converted into a matrix switching signal corresponding to the micro-electrostatic lens array; S4. A focusing voltage is applied to the micro-electrostatic lens unit corresponding to the position to be exposed, putting it in a conducting state, allowing the electron beam to pass along the axial direction and enter the electron scaling and focusing unit; S5. A deflection voltage is applied to the micro-electrostatic lens unit corresponding to the position not to be exposed, putting it in a turning-off state, deflecting the electron beam and irradiating it onto the aperture plate for absorption; S6. The electron beam from the conducting unit is zoomed and focused by the electron scaling and focusing unit, passes through the light-transmitting hole of the aperture plate, and forms a nanoscale parallel exposure spot corresponding to the pattern on the wafer surface; S7. After completing one frame of imaging exposure, the vacuum sample stage moves stepwise to repeat the exposure process, achieving large-area pattern splicing processing.

[0007] Beneficial effects Using a unified electronic source results in high brightness, good uniformity, and long lifespan, avoiding the consistency and reliability issues of field emission arrays; The micro-electrostatic lens array uses pure electric field control to achieve electron beam switching, has no mechanical moving parts, can be monolithically integrated through MEMS technology, and is compatible with CMOS driving circuits; The integrated electronic scaling and focusing unit enables variable magnification imaging exposure, which can be adapted to the micro-nano fabrication needs of different scales and resolutions on the same system; It enables scanning-free, one-frame parallel electron beam exposure, significantly improving exposure efficiency, and can be used in high-end nano-manufacturing scenarios such as mask preparation, quantum devices, and advanced packaging. The system has a simple structure, low alignment difficulty, and strong scalability, which is conducive to realizing a new generation of electron beam lithography equipment that is miniaturized, low-cost, and highly reliable.

Claims

1. A parallel electron beam imaging lithography system based on a micro-electrostatic lens array, characterized in that, The system comprises, in sequence along the direction of electron beam movement: a unified electron source, a micro-electrostatic lens array, an electron scaling and focusing unit, an aperture plate, and a vacuum sample stage; it also includes a drive circuit electrically connected to the micro-electrostatic lens array and the electron scaling and focusing unit; the unified electron source provides a continuous and large-area uniform electron beam current; the micro-electrostatic lens array consists of multiple independently controllable micro-electrostatic lens units, each unit including a focusing electrode and a deflection electrode, used to control the conduction or deflection of the electron beam through voltage control; the electron scaling and focusing unit consists of multiple levels of coaxial electrostatic electrodes, used to change the imaging scaling magnification of the electron beam by adjusting the voltage ratio of each level of electrodes; the aperture plate allows the electron beam in the conducting state to pass through and absorbs the electron beam deflected in the deflected state; the drive circuit controls the on / off state of each micro-electrostatic lens unit according to the pattern to be exposed and configures the scaling magnification of the electron scaling and focusing unit; when the system is working, the electron beam of the conducting unit is focused by the electron scaling and focusing unit and projected onto the wafer, while the electron beam of the deflected unit is blocked by the aperture plate, thereby forming a variable magnification parallel imaging exposure pattern corresponding to the pattern on the wafer surface.

2. A parallel electron beam imaging lithography control method based on a micro-electrostatic lens array, characterized in that, include: A continuous and uniform electron beam is generated by a unified electron source to fully irradiate the micro-electrostatic lens array; Based on the target exposure resolution, the electrode voltage of the electronic scaling and focusing unit is configured through the driving circuit to set the imaging scaling factor; the image to be exposed is converted into a matrix switching signal of the micro-electrostatic lens array; Focusing voltage or deflection voltage is applied independently to each micro-electrostatic lens unit, so that the corresponding electron beam is either conducted or deflected and blocked; the conducted electron beam is zoomed and focused by the electronic scaling and focusing unit, and passes through the aperture plate to form parallel nano-exposure patterns on the wafer surface; multi-frame stitching is achieved by stepping the vacuum sample stage to complete large-area exposure.

3. The system according to claim 1, characterized in that, The micro-electrostatic lens array is monolithically integrated using MEMS technology, with each unit being mutually insulated and independently addressable.

4. The system according to claim 1, characterized in that, The electronic zoom focusing unit achieves continuously variable magnification or reduction imaging through the voltage ratio of multi-level electrostatic electrodes.