Search

CN-121985855-A - Micro-bump preparation process of flexible sensor, and photoetching template position detection device and method

CN121985855ACN 121985855 ACN121985855 ACN 121985855ACN-121985855-A

Abstract

The application belongs to the technical field of flexible sensor manufacturing, and relates to a micro-bump preparation process of a flexible sensor, a photoetching template position detection device for the process and a detection method. The preparation process includes forming notch in the surface of the silicon substrate corresponding to the photoresist column, spin coating photoresist to the surface of the silicon substrate, filling photoresist in the notch, photoetching the photoresist with photoetching template with shading area corresponding to the target photoresist column, developing to form photoresist column array on the surface of the silicon substrate, heat reflux the silicon substrate, contracting the photoresist column array into photoresist ball array with surface tension to form photoresist ball array, embedding the bottom of the photoresist ball into the notch of the silicon substrate, dry etching to etch the left and right sides of the photoresist ball, and etching the spherical surface to obtain micro salient point. The application can avoid the outward collapse of the rubber ball during the thermal reflow and ensure the smooth formation of the micro-convex points in the subsequent spherical crown etching procedure.

Inventors

  • WANG XIN
  • LI JIN

Assignees

  • 西安博研微纳信息科技有限公司
  • 苏州研材微纳科技有限公司
  • 苏州美图半导体技术有限公司

Dates

Publication Date
20260505
Application Date
20260202

Claims (10)

  1. 1. The micro-bump preparation process of the flexible sensor is characterized by comprising the following steps of: S1, selecting a silicon wafer substrate for a flexible sensor, wherein a groove is formed on the surface of the silicon wafer substrate corresponding to a target rubber column; s2, carrying out photoetching exposure on the cured photoresist by adopting a photoetching template, wherein a shading area corresponding to the position of a target photoresist column is arranged on the photoetching template, and developing the photoresist column by using a developing solution after exposure to form a photoresist column array on the surface of a silicon wafer substrate; S3, placing the silicon wafer substrate on a hot plate for thermal reflux, shrinking the rubber column array into a rubber ball array by means of surface tension, and embedding the bottom of the rubber ball into the groove; S4, performing step etching on the left side and the right side of the rubber ball by adopting a dry etching process, and then etching the spherical surface morphology of the salient points to obtain the micro salient points.
  2. 2. The process of claim 1, wherein the glue column has a diameter smaller than the diameter of the groove, and when the bottom of the glue column is embedded into the groove and heated to a viscous state, the flow of the glue column is constrained by intermolecular forces of similar substances of photoresist in the groove to limit the diameter of the glue ball and prevent the glue ball from collapsing outwards.
  3. 3. The micro bump preparation process according to claim 1, wherein in step S4, step etching is firstly performed, SF 6 is used as main etching gas, C 4 F 8 is mixed and introduced into a cavity to form a passivation layer to protect a side wall, vertical steps on the outer side of a bump are obtained after etching, spherical morphology of the bump is etched, SF 6 is used as main etching gas, CF 4 is used as auxiliary etching gas to adjust the height and curvature radius of a silicon bump, and a micro bump array with the diameter of 1000-1200 mu m and the height of 15-25 mu m is obtained.
  4. 4. The micro-bump preparation process according to claim 1, wherein in step S1, the spin coating process comprises vacuum assisted self-leveling treatment, namely placing a silicon wafer substrate in a vacuum chamber for standing after spin coating, removing residual micro bubbles in the grooves by utilizing pressure difference, enabling photoresist liquid level in the grooves to be level and fused with a photoresist layer on the surface of the substrate, performing sectional pre-baking on a hot plate, and raising a temperature curve in a step shape to eliminate surface waves caused by internal stress of the photoresist layer.
  5. 5. A flexible sensor based on micro-bumps is characterized by comprising a silicon wafer substrate, grooves formed in the surface of the silicon wafer substrate, and micro-bumps arranged on the grooves, wherein the bottoms of the micro-bumps are embedded into the grooves to prevent downward collapse during preparation, the micro-bumps are in a spherical crown shape, and vertical steps are arranged on two sides of each micro-bump, and the flexible sensor is manufactured through the preparation process according to claim 1, 2 or 3.
  6. 6. The device for detecting the position of the photoetching template for preparing the micro-salient points of the flexible sensor is characterized in that the photoetching template is covered on the photoresist, and a capacitive coupling area which is consistent with the shape of the bottom surface of a groove is arranged on the photoetching template, wherein the capacitive coupling area is a metal layer and comprises a shading area and a light transmission area which is positioned at the periphery of the shading area and takes the shape of a ring; The detection device further includes: The capacitive detection unit comprises a capacitive detector, wherein the positive electrode of the capacitive detector is electrically connected with the capacitive coupling area, and the negative electrode of the capacitive detector is electrically connected with the groove; and the displacement driving unit comprises a triaxial micro-moving table and is used for driving the photoetching template or the silicon wafer substrate to move.
  7. 7. The detecting device according to claim 5, further comprising an anti-interference shielding case which is grounded and covers the connection line between the capacitive coupling area and the capacitive detecting unit, wherein an electromagnetic shielding coating is coated on the inner wall of the shielding case, and the bottom of the groove is covered with a metal conductive layer.
  8. 8. The photoetching template position detection method for preparing the micro-convex points of the flexible sensor is characterized by comprising the following steps of: Placing a photoetching template on a photoresist of a silicon wafer substrate, wherein the photoresist has a flat surface, and pre-positioning the photoresist to enable the groove to be approximately aligned with the capacitive coupling area; Controlling a displacement driving unit to drive a silicon wafer substrate or a photoetching template to carry out crisscross scanning along the X-axis and Y-axis directions, and acquiring capacitance values in real time by a capacitance detector in the scanning process to respectively generate an X-axis displacement-capacitance value curve and a Y-axis displacement-capacitance value curve; The data processing unit analyzes the capacitance data and determines displacement coordinates corresponding to capacitance peaks in the X-axis displacement-capacitance value curve and the Y-axis displacement-capacitance value curve, wherein the coordinates are coaxial positions of the groove and the capacitive coupling area; And controlling the displacement driving unit to move the silicon wafer substrate or the photoetching template to the coaxial position and locking the displacement table to finish accurate coaxial alignment.
  9. 9. The detection method of claim 4, wherein the data processing unit performs Gaussian fitting on the X-axis displacement-capacitance value curve and the Y-axis displacement-capacitance value curve by using a peak fitting algorithm, and extracts the vertex of the fitted curve as a displacement coordinate corresponding to the capacitance peak.
  10. 10. The detection method according to claim 4, wherein the lithography template is provided with at least three groups of capacitive coupling areas which are respectively positioned at the edge of the lithography template and distributed in an equilateral triangle or rectangle; and by combining fine adjustment of the displacement driving unit in the Z-axis direction, the horizontal inclination of the surface of the photoresist is judged by calculating the difference delta C of capacitance values of each point, and the horizontal inclination is fed back to the displacement driving unit to adjust the included angle between the photoetching template and the silicon wafer substrate.

Description

Micro-bump preparation process of flexible sensor, and photoetching template position detection device and method Technical Field The invention belongs to the technical field of flexible sensor manufacturing, and particularly relates to a micro-bump preparation process of a flexible sensor, a photoetching template position detection device for the process and a detection method. Background With the rapid development of the fields of the internet of things, wearable electronic equipment, medical health monitoring and the like, the flexible sensor has the characteristics of light weight, flexibility, stretchability and the like, can adapt to the surface with complex shape and dynamic change, and the demand is growing increasingly. Microstructured designs (e.g., hemispherical, stepped micro-bumps) are critical to improving the sensitivity and response speed of flexible sensors, and can significantly enhance the electrical response signal by increasing the rate of deformation of the sensor when it is stressed. However, the conventional micro-bump preparation process of the flexible sensor has a plurality of defects that the traditional photoetching template method can realize high-precision micro-structure preparation, but has high cost and complex process, is difficult to produce in large scale, the natural template method has low cost, but has poor controllability of the micro-structure, the consistency and stability of the device cannot be ensured, particularly as shown in figure 1, the glue column flow is not controlled during thermal reflow, the problem that the glue balls collapse outwards easily occurs, full bumps cannot be formed, and the collapsed glue balls are difficult to provide enough etching thickness in the subsequent process of etching the spherical cap, so that the shape and size requirements of the micro-bumps cannot be met. On the other hand, in the preparation process of the micro-bumps, the precise alignment of the photoetching template and the silicon wafer substrate is a core for ensuring the regular and consistent positions of the micro-bumps, the prior alignment technology is mostly dependent on optical detection, is easy to be interfered by ambient light, and has limited alignment precision. Aiming at the technical problems, the invention provides a flexible sensor micro-bump preparation process for avoiding glue ball collapse, and a high-precision and anti-interference photoetching template position detection device and method, which effectively solve the defects in the prior art. Disclosure of Invention The invention provides a preparation process of a micro-bump of a flexible sensor, which aims at solving the problem that the existing micro-bump rubber ball of the flexible sensor is easy to collapse in the hot reflow process and comprises the following steps: S1, selecting a silicon wafer substrate for a flexible sensor, wherein a groove is formed on the surface of the silicon wafer substrate corresponding to a target rubber column; s2, carrying out photoetching exposure on the cured photoresist by adopting a photoetching template, wherein a shading area corresponding to the position of a target photoresist column is arranged on the photoetching template, and developing the photoresist column by using a developing solution after exposure to form a photoresist column array on the surface of a silicon wafer substrate; S3, placing the silicon wafer substrate on a hot plate for thermal reflux, shrinking the rubber column array into a rubber ball array by means of surface tension, and embedding the bottom of the rubber ball into the groove; S4, performing step etching on the left side and the right side of the rubber ball by adopting a dry etching process, and then etching the spherical surface morphology of the salient points to obtain the micro salient points. Preferably, the diameter of the rubber column is smaller than that of the groove, and after the bottom of the rubber column is embedded into the groove, when the rubber column is heated to a viscous state, the flow of the rubber column is restrained by intermolecular forces of similar substances of photoresist in the groove, so that the diameter of the rubber ball is limited and the rubber ball is prevented from collapsing outwards. Preferably, step S4 comprises the steps of firstly performing step etching, taking SF 6 as main etching gas, mixing C 4F8 and introducing the main etching gas into a cavity to form a passivation layer to protect a side wall, etching to obtain a vertical step on the outer side of a bump, and then etching the spherical surface shape of the bump, taking SF 6 as main etching gas, taking CF 4 as auxiliary etching gas to adjust the height and the curvature radius of the silicon bump, thus obtaining the micro bump array with the diameter of 1000-1200 mu m and the height of 15-25 mu m and with the low height-diameter ratio. Further, in step S1, the spin coating process comprises vacuum assisted self-leveling