Search

CN-122003108-A - Lithium tantalate wafer etching method with high etching uniformity and controllable rate

CN122003108ACN 122003108 ACN122003108 ACN 122003108ACN-122003108-A

Abstract

The invention belongs to the field of semiconductor materials, and relates to a lithium tantalate wafer etching method with high etching uniformity and controllable rate, which comprises the following steps of cleaning sliced wafers; the method comprises the steps of carrying out primary corrosion on a wafer by using a mixed strong acid corrosion solution, carrying out secondary corrosion on the wafer by using a composite corrosion solution containing acid, a surfactant and a buffer, carrying out tertiary corrosion on the wafer by using a weak acid complexing corrosion solution containing weak acid, a complexing agent and a corrosion auxiliary agent, and finally spin-drying the wafer to obtain the uniformly corroded lithium tantalate wafer. The lithium tantalate wafer etching method is simple in process, and the three-stage progressive etching process of 'surface repair by strong acid rapid etching-composite etching solution-surface treatment by weak acid complexing etching solution to optimize surface quality' is adopted, so that the surface quality is improved step by step while the etching efficiency is ensured, the etching rate can be regulated and controlled, the subsequent polishing removal amount is reduced, the problems of etching uniformity and etching quality control are solved, and the subsequent processing difficulty is reduced.

Inventors

  • XU QIUFENG
  • KONG HUI
  • ZHANG RUICHAO
  • SHEN HAO
  • XU YAOHUI

Assignees

  • 天通控股股份有限公司
  • 天通精美科技有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (9)

  1. 1. A lithium tantalate wafer etching method with high etching uniformity and controllable rate, which is characterized by comprising the following steps: a) Cleaning, namely providing a sliced lithium tantalate wafer and cleaning the sliced lithium tantalate wafer by using a cleaning solution; b) C, performing primary corrosion, namely corroding the cleaned wafer obtained in the step a) by using a mixed strong acid corrosive liquid; c) Performing secondary corrosion, namely corroding the wafer subjected to the primary corrosion obtained in the step b) by using a composite corrosion solution, wherein the composite corrosion solution comprises acid, a surfactant and a buffer; d) C, performing third etching, namely etching the wafer subjected to the second etching obtained in the step c) by using weak acid complexing etching liquid, wherein the weak acid complexing etching liquid comprises weak acid, complexing agent and etching auxiliary agent; e) Spin-drying, namely spin-drying the wafer subjected to three times of corrosion obtained in the step d) to obtain a lithium tantalate wafer with uniform corrosion; in the step c) and the step d), a kick function is started to enable the corrosive liquid to be in a convection state, and a liquid supplementing device is arranged.
  2. 2. The method of claim 1, wherein in step a), ultrasonic cleaning is used, and the cleaning solution comprises one of potassium hydroxide, sodium hydroxide, and tetramethylammonium hydroxide solution.
  3. 3. The lithium tantalate wafer etching method with high etching uniformity and controllable rate according to claim 1, characterized in that in the step b), the mixed strong acid etching solution comprises hydrochloric acid and nitric acid, the etching temperature is normal temperature, the etching time is 20-80 min, the concentration of the hydrochloric acid is 30-50wt%, the concentration of the nitric acid is 50-65wt%, and the volume ratio of the hydrochloric acid to the nitric acid is (1-5): 1.
  4. 4. The method for etching a lithium tantalate wafer with high etching uniformity and controllable rate according to claim 1, wherein in the step C), the etching temperature is 30-90 ℃ and the etching time is 30-260 min, the acid comprises nitric acid and hydrofluoric acid, the buffering agent comprises one or more of sodium fluoride, ammonium fluoride, potassium fluoride, sodium dihydrogen phosphate and sodium acetate, and the surfactant comprises one or more of polyvinyl alcohol, alkylphenol ethoxylate and sodium dodecyl sulfonate.
  5. 5. The method for etching a lithium tantalate wafer with high etching uniformity and controllable rate according to claim 4, wherein in the step c), the concentration of hydrofluoric acid is 40-50wt%, the concentration of nitric acid is 50-65wt%, and the volume ratio of hydrofluoric acid, nitric acid, surfactant and buffer is (2-5): 3-8): 0.05-0.2): 0.5-1.
  6. 6. The method for etching a lithium tantalate wafer with high etching uniformity and controllable rate according to claim 1, wherein in the step d), the weak acid comprises citric acid, the complexing agent comprises ethylenediamine tetraacetic acid, the etching auxiliary agent comprises polyethylene glycol, the etching temperature is 40-60 ℃, and the etching time is 30-150 min.
  7. 7. The method for etching a lithium tantalate wafer with high etching uniformity and controllable rate according to claim 6, wherein in the step d), the volume ratio of ethylenediamine tetraacetic acid, citric acid and polyethylene glycol is (5-10): (1.5-3): 1.
  8. 8. The method for etching a lithium tantalate wafer with high etching uniformity and controllable rate according to claim 1, wherein the steps c) and d) are performed in a quartz tank, and a concentration detection device is further provided in the quartz tank, and when the concentration detection device detects that the etching solution concentration is lower than a set value, the etching solution is automatically replenished to the set concentration by a replenishing device.
  9. 9. The lithium tantalate wafer etching method with high etching uniformity and controllable rate according to claim 1, characterized in that in step e), the spin-drying rotation speed is accelerated to 1000-3000 rpm at an acceleration of 50-300 rpm/s, then high-purity nitrogen with a temperature of 20-40 ℃ is introduced, the nitrogen flow is 0.5-5L/min, the blowing direction forms an included angle of 15-40 ℃ with the rotation direction, the duration is 30-60 s, and the spin-drying time is 3-8 min.

Description

Lithium tantalate wafer etching method with high etching uniformity and controllable rate Technical Field The invention relates to the field of semiconductor materials, in particular to a lithium tantalate wafer etching method with high etching uniformity and controllable rate. Background The lithium tantalate (LiTaO 3, LT for short) crystal has excellent piezoelectric effect, photoelectric effect, photorefractive effect and other various photoelectric properties, and is an important multifunctional crystal material. The lithium tantalate serving as the piezoelectric crystal has the advantages of high reaction speed, low temperature coefficient, good thermal stability and the like, can be used for manufacturing products such as filters, resonators, Q-switching switches, pyroelectric detectors and the like, and is widely applied to the fields of communication technology, electronic technology, remote sensing telemetry and the like. Etching processes are key steps in the semiconductor manufacturing process, and typically, semiconductor materials are chemically reacted in a specific etching solution to effect processing of the surface or internal structure of the material. After slicing lithium tantalate, the surface of the wafer may be damaged mechanically and thermally to form a damaged layer, which adversely affects the performance and surface quality of the crystal, and the damaged layer may be removed effectively by etching, while the surface of the cut wafer may have a certain degree of unevenness, and the flatness and roughness of the wafer surface may be improved by etching. The lithium tantalate is usually subjected to corrosion processing by nitric acid, hydrofluoric acid, hydrochloric acid and the like after being sliced, and the acidic solution has strong corrosiveness to the lithium tantalate, so that higher corrosion rate can be realized in a shorter time, the surface corrosion rate of the traditional corrosion method in the corrosion process is difficult to accurately control, the surface roughness and uniformity of a wafer are poor, defects such as corrosion pits and back flowers are easy to generate, the performance and quality of the lithium tantalate wafer are influenced, and the application of the lithium tantalate in the fields of high-end electronic devices and optical devices is restricted. Therefore, how to optimize the etching process, control the etching rate, and improve the surface uniformity of the lithium tantalate wafer is a problem to be solved in the current lithium tantalate etching process. The invention patent No. CN112133649A discloses a large-size wafer uniform high-temperature corrosion device and a corrosion method thereof, wherein a wafer is heated by a heating table, meanwhile, the rotation speed of a wafer fixing table, the translation speed and the rotation speed of a conveying arm are coordinated, the corrosion liquid is uniformly sprayed on the surface of the wafer by a liquid spraying nozzle, and high-temperature corrosion is realized. Therefore, the prior art lacks a lithium tantalate wafer etching method which ensures the etching uniformity and has controllable etching rate. Disclosure of Invention The invention provides a lithium tantalate wafer etching method with high etching uniformity and controllable etching rate, which aims to overcome the defects of the prior art. The technical scheme adopted by the invention for solving the problems is that the lithium tantalate wafer corrosion method with high corrosion uniformity and controllable rate comprises the following steps: a) Placing the sliced lithium tantalate wafer into a cleaning solution, ultrasonically cleaning to remove surface residual glue, cuttings and mortar, and cleaning with pure water to remove residual cleaning agent on the surface of the wafer; b) Placing the wafer cleaned in the step a) into a container which is corrosion-resistant and can drain solution, then placing the container into a quartz tank containing mixed strong acid corrosive liquid, fixing, corroding for 20-80 min at normal temperature, and cleaning the residual corrosive liquid on the surface of the wafer by using pure water after corrosion is finished; c) Placing the wafer processed in the step b) into a quartz tank containing composite corrosive liquid for secondary corrosion, heating to 30-90 ℃, carrying out billowing corrosion for 30-260 min, and cleaning the residual corrosive liquid on the surface of the wafer by using pure water after the corrosion is finished; d) Placing the wafer treated in the step C) into a quartz tank containing weak acid complexing corrosive liquid for three times of corrosion, heating to 40-60 ℃, carrying out billowing corrosion for 30-150 min, and cleaning the residual corrosive liquid on the surface of the wafer by using pure water after the corrosion is finished; e) Spin-drying, namely spin-drying the wafer subjected to the pure water cleaning in the step d) in a spin dryer to obtain the lithiu