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CN-121974294-A - Method for controlling bottom dimension of MEMS device etching structure by regulating Bosch process

CN121974294ACN 121974294 ACN121974294 ACN 121974294ACN-121974294-A

Abstract

The application relates to a method for controlling the bottom dimension of an etching structure of a MEMS device by regulating and controlling a Bosch process, and relates to the technical field of MEMS preparation; in the etching process, along with the increase of the etching depth, the R value is adjusted according to a preset dynamic regulation and control mechanism so as to control the shape of the side wall and the bottom size of the etched structure, thereby controlling the etching process and finally solving the technical problem that the bottom size of the etched structure of the MEMS device is uncontrollable.

Inventors

  • Li Puzhuo
  • ZHAO CHUN
  • LEI HAO

Assignees

  • 苏州市华芯云睿微电子科技有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. A method for controlling the bottom dimension of an etched structure of a MEMS device by modulating a Bosch process, comprising the steps of: S1, defining R, wherein a single standard Bosch process cycle comprises an etching sub-cycle and a passivation sub-cycle which are alternately performed, and defining the ratio of etching time of the etching sub-cycle to passivation time of the passivation sub-cycle as R; S2, providing a MEMS device to be etched, wherein the MEMS device is aimed at etching the depth, width and bottom dimension of the structure; And S3, in the etching process, along with the increase of the etching depth, adjusting the R value according to a preset dynamic regulation mechanism so as to control the shape and the bottom size of the side wall of the etched structure.
  2. 2. The method of claim 1, wherein the dynamic adjustment mechanism is configured to set an initial R value that gradually decreases or increases as the etch depth increases.
  3. 3. The method of claim 1, further comprising monitoring a current etch depth with a real-time process monitor and feeding back monitoring data to a process control system, the process control system triggering an adjustment of the R value based on the monitoring data and the dynamic tuning mechanism.
  4. 4. The method of claim 1, wherein the structure to be etched of the MEMS device is any one of a deep trench, a via, a cantilever, a comb structure, a cavity.
  5. 5. The method of claim 1, wherein the aspect ratio of the structure to be etched of the MEMS device is 0.5:1-100:1.
  6. 6. The method of claim 1, wherein in step S1, the etching time of the etching sub-period and the passivation time of the passivation sub-period are independently adjustable, respectively.
  7. 7. The method of claim 6, wherein the etching gas employed during the etching sub-cycle process is a fluorine-containing etching gas and the passivation gas employed during the passivation sub-cycle process is a fluorine-containing carbon polymer deposition gas.
  8. 8. The method of claim 7, wherein the etching gas is SF 6 and the passivation gas is C 4 F 8 .
  9. 9. The method of claim 1, wherein the dynamic adjustment range of the R value is 2.8-4.2.
  10. 10. The method of claim 1, further comprising an endpoint detection step of further trimming the R value to correct bottom dimension accuracy when the etch depth approaches the predetermined etch depth.

Description

Method for controlling bottom dimension of MEMS device etching structure by regulating Bosch process Technical Field The application relates to the technical field of MEMS preparation, in particular to a method for controlling the bottom dimension of an etching structure of an MEMS device by regulating and controlling a Bosch process. Background In the technical field of micro-electro-mechanical systems (MEMS) fabrication, deep silicon etching is a key process for forming etched structures such as accelerometers, gyroscopes, micromirrors, pressure sensors, and the like. However, the prior related art still has many limitations in practical application: 1) The bottom critical dimension (Bottom Critical Dimension, CD) of the etched structure in the traditional technology is mainly determined by the photoetching pattern, the bottom CD is fixed after the photomask is shaped, and the photomask needs to be prepared again if the photomask needs to be adjusted, so that the method is time-consuming, labor-consuming, high in cost, and difficult to quickly respond to market demand change, and development progress and production flexibility are seriously affected; 2) In some technologies, by introducing bottom polymer regulation gas pulse in the Bosch process, although the thickness of the bottom passivation layer can be moderately increased to inhibit excessive etching of the bottom corner, the risk of residues is easily introduced, and the cleaning step is required to be additionally optimized; 3) In addition, a scheme of adopting a variable power/variable air flow dynamic etching strategy is adopted, and the profile morphology is regulated and controlled by changing the plasma characteristic by adjusting the RF power, the air flow or the pressure, but the control capability of the plasma on the bottom CD is limited, and the non-uniformity or the profile distortion of an etching structure is easily caused. Meanwhile, when the Bosch process is applied to manufacturing of an etching structure of an MEMS device, the problem of difficult control of the bottom dimension is also faced, the bottom is influenced by factors such as ion bombardment angle, uneven deposition of a side wall polymer, residual bottom polymer and the like, the bottom is easy to generate an undercut or bottle-shaped phenomenon, the bottom landing dimension is difficult to precisely control, and along with the increase of the etching depth, the fluctuation of the etching rate and the side wall morphology can occur, so that the lateral dimensions at different depths are inconsistent. In the prior art, the etching depth is controlled mainly by adjusting the total etching time, the gas flow or the power, and the bottom CD is not regulated and controlled enough, so that the problems restrict the precision machining and the industrialization development of the etching structure of the MEMS device, and a novel process method is needed to solve the problems. Disclosure of Invention The invention aims to solve the technical problem that the bottom size of an etching structure of an MEMS device is uncontrollable. In order to achieve the above object, the present application provides a method for controlling the bottom dimension of an etched structure of a MEMS device by adjusting and controlling a Bosch process, comprising the steps of: S1, defining R, wherein a single standard Bosch process cycle comprises an etching sub-cycle and a passivation sub-cycle which are alternately performed, and defining the ratio of etching time of the etching sub-cycle to passivation time of the passivation sub-cycle as R; S2, providing a MEMS device to be etched, wherein the MEMS device is aimed at etching the depth, width and bottom dimension of the structure; And S3, in the etching process, along with the increase of the etching depth, adjusting the R value according to a preset dynamic regulation mechanism so as to control the shape and the bottom size of the side wall of the etched structure. As a further improvement of the application, the dynamic regulation mechanism is that an initial R value is set, and the R value is gradually reduced or increased along with the increase of the etching depth. As a further improvement of the application, the method also comprises the steps of monitoring the current etching depth by using a real-time process monitoring device and feeding back monitoring data to a process control system, wherein the process control system triggers the adjustment of the R value according to the monitoring data and the dynamic regulation and control mechanism. As a further improvement of the application, the structure to be etched of the MEMS device is any one of a deep groove, a through hole, a cantilever beam, a comb tooth structure and a cavity. As a further improvement of the application, the depth-to-width ratio of the structure to be etched of the MEMS device is 0.5:1-100:1. As a further improvement of the present application, in step S1, the etching