Technology for double-sided photoetching of small-size device
By using a special mold and solid medium to fix the device and then positioning it with a three-dimensional coordinate measuring machine, the problem of consistency between fixing and photolithography of small-volume devices was solved, achieving high-precision photolithography and efficient fabrication.
Patent Information
- Application Number
- CN202511527189.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-23
- Publication Date
- 2026-02-27
AI Technical Summary
In existing technologies, it is difficult to ensure consistency between the fixation of small-volume devices and double-sided photolithography, resulting in problems such as device deformation, damage, large positioning errors, and low efficiency, which cannot meet the fabrication requirements of high-end devices.
A method combining a dedicated mold with a solid medium for fixing and positioning with a three-dimensional coordinate measuring machine is adopted. By adapting the hollow area of the mold to the shape of the device, using a solid medium for fixing and surface smoothing, and combining it with the fabrication of a high-precision mask to achieve photolithography positioning, the device is ensured to be stable and undamaged and to achieve high-precision photolithography.
It achieves stable device fixation and high-precision photolithography, reduces photolithography errors, improves work efficiency and device yield, and meets the fabrication requirements of high-end small-volume devices.
Smart Images
Figure CN121578596A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photolithography, and more specifically to a technique for double-sided photolithography of small-volume devices. Background Technology
[0002] In fields such as electronic information, microelectromechanical systems (MEMS), and precision sensing, the application of small-volume devices (such as microchips, core components of microsensors, and precision electronic components) is becoming increasingly widespread. The performance of these devices often depends on high-precision double-sided lithography—precisely fabricating patterned structures on the top and bottom surfaces of the device to achieve key functions such as circuit connections and functional layer layout. Therefore, double-sided lithography technology for small-volume devices plays a decisive role in the final performance of the device.
[0003] Currently, the core challenges in double-sided lithography for small-volume devices lie in ensuring stable device fixation and maintaining lithographic consistency across the upper and lower surfaces. Existing technologies for fixing small-volume devices primarily employ mechanical clamping, adhesive fixing, or simple carrier-based methods. Mechanical clamping directly holds the device edges with fixtures; however, small-volume devices are typically in the millimeter or even micrometer range, making precise control of clamping force difficult, easily leading to device deformation and edge damage. Furthermore, the device is prone to slight displacement during clamping, directly causing deviations in the lithographic pattern position. While adhesive fixing reduces mechanical damage, adhesive residue can easily remain on the device surface, potentially causing secondary damage during subsequent cleaning processes. Additionally, the cured adhesive can generate shrinkage stress, reducing surface flatness and affecting the alignment accuracy of double-sided lithography. Simple carrier-based methods often use flat carriers without specific positioning structures, allowing the device to slide easily. Moreover, coordinating the surface flatness of the carrier and the device is difficult, requiring multiple adjustments during upper and lower surface lithography, resulting in low efficiency.
[0004] Furthermore, existing technologies lack a systematic design for the fixation and photolithography assistance of small-volume devices. On the one hand, the choice of fixation medium is limited; liquid media are prone to bubbles or uneven shrinkage after solidification, while solid media lack sufficient compatibility in filling and fixation, making it difficult to balance fixation stability and ease of device removal. On the other hand, there is a lack of corresponding solutions for smoothing the upper and lower surfaces of the fixed device and auxiliary structure, leading to optical path refraction deviations due to surface unevenness during photolithography, further increasing photolithography errors. These problems collectively make it difficult to achieve high precision in double-sided photolithography of small-volume devices, with alignment errors often at the micrometer level or even higher. Moreover, the operation efficiency is low, and device yield is affected, failing to meet the fabrication requirements of high-end small-volume devices. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to achieve the above objectives. The technical solution adopted by the present invention is: a double-sided photolithography technique for small-volume devices, comprising a dedicated mold and a corresponding operating procedure; the dedicated mold includes a mold body, the central part of which has a hollowed-out area adapted to the shape of the small-volume device to be photolithographically lithographically oriented, the hollowed-out area being used to accommodate the device, and the gap between the hollowed-out area and the device being no greater than 0.5mm; the outer periphery of the mold body has four columnar holes, the inner walls of which can be provided with internal threads for securing the mold during the photolithography process via external fasteners. The device is securely positioned within the mold. The supporting operation process includes: introducing a solid medium (such as glass powder) into the hollow area, heating and curing it, and then fixing the device within the hollow area; smoothing the upper and lower surfaces of the fixed device and the mold by grinding and polishing, so that the flatness error of the upper and lower surfaces after processing does not exceed 0.01mm; determining the three-dimensional coordinates of the required photolithography position on the device using a three-dimensional coordinate measuring instrument and other testing instruments, and making a mask based on the coordinates (the alignment accuracy between the mask and the photolithography position is not greater than 50nm), and then using the mask to complete the double-sided photolithography operation of the device.
[0006] Based on the above technical solution, the mold body is made of stainless steel, and the surface roughness of its upper and lower surfaces is no more than 50nm; the solid medium can be selected from suitable curable solid materials according to the material characteristics of the device, so as to ensure the fixing strength while facilitating the removal of the device after photolithography.
[0007] Compared with the prior art, the advantages of the present invention are as follows:
[0008] Superior fixing method: By using a hollow area that matches the shape of the device and a solid medium for fixing, it avoids the deformation or damage of the device caused by mechanical clamping, and overcomes the problems of residual pollution and stress shrinkage caused by adhesive fixing. It can achieve stable and damage-free fixing of the device, and the displacement error of the device after fixing can be controlled within a small range.
[0009] Controllable surface flatness: The mold body itself has low surface roughness characteristics, and after fixing, the upper and lower surfaces of the device and the mold are subjected to targeted smoothing treatment, which can control the flatness error within 0.01mm, effectively reducing the optical path refraction deviation during photolithography and providing a foundation for high-precision photolithography.
[0010] Improved lithography precision: By combining the precise positioning of a 3D coordinate measuring machine with the fabrication of a high-precision mask, the alignment precision of the lithography position can be controlled within 50nm, which significantly improves the alignment error problem at the micron level or even higher in the existing technology and enhances the consistency of double-sided lithography.
[0011] The operation process is seamless: it integrates mold fixing, smoothing, precise positioning and photolithography in a seamless process, eliminating the need for multiple adjustments to device positioning, reducing operation steps and improving the efficiency and yield of double-sided photolithography for small-volume devices. Attached Figure Description
[0012] Figure 1 A three-dimensional schematic diagram of the mold
[0013] Figure 2 for Figure 1 A top view of the mold.
[0014] Figure 3 for Figure 1 A front view diagram of the mold. Detailed Implementation
[0015] The present technology will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present technology and are not intended to limit the present technology.
[0016] like Figure 1 The diagram shown is a schematic of a mold structure for double-sided photolithography of small-volume devices in this embodiment of the technology. The mold includes a mold body 1, which is made of aluminum alloy and has an overall rectangular structure with an area of two inches. The top and bottom surfaces are pre-polished, and the surface roughness is controlled to be within 40 nm (better than the requirements of the claims). (Seeking the 50nm limit)
[0017] The mold body has a hollowed-out area in the middle, which is used to place small-volume devices to be photolithographically etched. Preferably, the shape of the hollowed-out area is adapted to the shape of the device to be photolithographically etched, and is set as a cylindrical cavity with an area of 2 inches. The gap between the hollowed-out area and the device is appropriate, which not only facilitates the placement of the device, but also allows for tight fixation through subsequent filling with solid medium.
[0018] The mold body has four columnar through holes A at its four corners. These through holes A extend along the thickness of the mold body and have internal threads on their inner walls. These threads allow for connection with external fasteners (such as bolts) to secure the mold on the photolithography platform. Furthermore, the walls of the columnar through holes A are chamfered to prevent damage to the threads during assembly.
[0019] The specific implementation steps of the double-sided photolithography operation in this technical embodiment are as follows:
[0020] Step 1: Placement and Fixation of Components
[0021] Place the cylindrical device B to be photolithographically patterned into the cutout area of the mold body 1, ensuring that the device axis is substantially aligned with the axis of the cutout area 2. Fill the gap between the cutout area and the device with a solid medium—preferably low-melting-point glass powder—so that the gap is completely covered, such as... Figure 3 As shown, a support layer prevents the medium from flowing out from the bottom of the mold. The mold is then placed on a heating table and heated at a certain rate to the melting point of the solid medium. This temperature is maintained for a certain time to allow the glass powder to melt and solidify, achieving rigid fixation between the device and the mold. It should be noted that transparent epoxy resin can also be used as the solid medium, achieving fixation through UV curing, which is suitable for devices that are not heat-resistant.
[0022] Step 2: Smoothing of upper and lower surfaces
[0023] After the solid medium has completely solidified, a grinding and polishing machine is used to treat both the top and bottom surfaces of the mold and the device. The grinding process involves coarse grinding followed by fine polishing. During this process, the mold surface is used as a reference surface to ensure that the flatness error between the device surface and the mold surface is controlled within 0.008 mm (better than the 0.01 mm limit in claim 6). After processing, residual abrasive on the surface is cleaned with anhydrous ethanol and then dried for later use.
[0024] Step 3: Determining the photolithography position
[0025] The mold with the device fixed is placed on the worktable of the measuring instrument, and positioned and fixed to the worktable of the measuring instrument through the columnar perforation 3 on the outer periphery of the mold. The measuring instrument is started, and the target area (such as the position of the electrode pattern) on the surface of the device to be photolithographically etched is scanned in three dimensions to obtain the center coordinates and contour dimensions of the target area. The scan data is processed by the instrument's built-in software and exported as the reference parameters for mask fabrication.
[0026] Step 4: Mask fabrication and photolithography
[0027] Based on the coordinate parameters obtained in step 3, a corresponding photomask is fabricated using an electron beam lithography system. The alignment deviation between the center of the photomask pattern and the center of the target area of the device is preset to 50 nm. The fabricated photomask is mounted on a double-sided lithography machine, and the mold is fixed to the stage of the lithography machine through the columnar perforation 3. Exposure lithography is performed on both the upper and lower surfaces of the device. During the exposure process, the automatic alignment system of the lithography machine is used for real-time calibration to ensure that the alignment accuracy of the lithographic patterns on the upper and lower surfaces does not exceed 50 nm.
[0028] Preferably, in step 1, if glass powder is used as the solid medium, the mold can be immersed in the solution for 5 minutes after photolithography to dissolve the glass powder and separate the device from the mold. After separation, there is no residual medium on the surface of the device. If epoxy resin is used, it can be dissolved and separated by immersing in the solution for 10 minutes. The operation is convenient and there is no damage to the device.
[0029] Furthermore, the mold body can also be made of stainless steel 304, suitable for scenarios requiring lightweight molds. It should be noted that the specific models and dimensional parameters involved in the above embodiments are merely illustrative examples. In actual applications, adjustments can be made according to the specifications of the device to be lithographicated (such as size, material, temperature resistance, etc.). As long as they fall within the scope of the claims of this technology, they are all within the protection scope of this technology. For example, if the device to be lithographicated is a square structure, the hollow area 2 can be correspondingly set as a square cavity, with the gap between it and the device still controlled within 0.5mm; the number of columnar through holes A can also be adjusted to 6 (evenly distributed around the mold perimeter) according to the fixing requirements, as long as the mold can be stably fixed.
[0030] The above description is only a preferred embodiment of the present technology. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present technology, and these improvements and modifications should also be considered within the scope of protection of the present technology.
Claims
1. A technique for double-sided photolithography of small-volume devices, characterized in that, The device includes a mold body with a hollowed-out area in the middle for placing a small-volume device to be photolithographically etched. Four columnar holes are provided around the periphery of the mold body for fixing the mold during photolithography. In use, a solid medium is introduced into the hollowed-out area to fix the small-volume device within it. The top and bottom surfaces of the fixed small-volume device and the mold are smoothed. Then, the required photolithography position on the small-volume device is determined using testing instruments. A corresponding photomask is fabricated based on the determined position, and the photolithography operation is performed on the small-volume device using the photomask.
2. The mold according to claim 1, characterized in that, The shape of the hollowed-out area is adapted to the shape of the small-volume device to be photolithographically etched, and the gap between the two is no more than 0.5 mm.
3. The mold according to claim 1, characterized in that, The solid medium is glass powder, which is introduced into the hollow area and then cured by heating to fix the small-volume device.
4. The mold according to claim 1, characterized in that, The inner wall of the columnar hole is provided with internal threads, which are used to fix the mold by connecting with external fasteners through threads.
5. The mold according to claim 1, characterized in that, The mold body is made of aluminum alloy, and the surface roughness of its upper and lower surfaces is no greater than 30nm.
6. The mold according to claim 1, characterized in that, When smoothing the upper and lower surfaces of small-volume components and molds, grinding and polishing are used, and the flatness error of the upper and lower surfaces after processing does not exceed 0.01mm.
7. The mold according to claim 1, characterized in that, The testing instrument is a three-dimensional coordinate measuring machine, used to accurately determine the three-dimensional coordinates of the required photolithography position on a small-volume device.
8. The mold according to claim 1, characterized in that, The alignment accuracy between the mask and the required photolithographic position on the small-volume device is no greater than 1 μm.