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CN-121992369-A - Preparation method and application of CVD-SiC focusing ring

CN121992369ACN 121992369 ACN121992369 ACN 121992369ACN-121992369-A

Abstract

The invention relates to the field of ceramic materials, and discloses a preparation method and application of a CVD-SiC focusing ring. The preparation method comprises the steps of 1) placing a graphite ring in a CVD furnace, heating to 1050-1150 ℃ under the condition of introducing hydrogen, 2) introducing HCl and hydrogen to clean the surface of the graphite ring, 3) heating to 1250-1300 ℃, insulating, introducing process gas comprising 5-9vol% of trichloromethylsilane, 86-91vol% of hydrogen and 2-6vol% of HCl to react to obtain the graphite ring with the surface plated with the CVD-SiC layer, and 4) machining, polishing and cleaning to obtain the CVD-SiC focusing ring. The CVD-SiC focusing ring prepared by adopting the CVD method has the characteristics of high purity, high density and high heat conductivity, and can meet the use requirement of semiconductor etching equipment.

Inventors

  • XIE SHENGQIANG
  • CHENG DONGYUAN
  • HAN CHAOYANG
  • CHEN JUNHUA
  • LI JINGRU

Assignees

  • 浙江富乐德半导体材料科技有限公司

Dates

Publication Date
20260508
Application Date
20251124

Claims (10)

  1. 1. A method for preparing a CVD-SiC focus ring, comprising: 1) Placing the graphite ring in a CVD furnace, and heating to 1050-1150 ℃ under the condition of introducing hydrogen; 2) HCl and hydrogen are introduced to clean the surface of the graphite ring; 3) Heating to 1250-1300 ℃, after heat preservation, introducing process gas comprising 5-9vol% of trichloromethylsilane, 86-91vol% of hydrogen and 2-6vol% of HCl for reaction to obtain a graphite ring with a CVD-SiC layer plated on the surface, wherein the crystal form of the CVD-SiC layer is beta-SiC grown by (111), the density is more than 3.19g/cm, and the thermal conductivity is more than 250W/(m.k); 4) And (5) machining, polishing and cleaning to obtain the CVD-SiC focusing ring.
  2. 2. The method of claim 1, wherein in step 1), the graphite ring is isostatically molded to have an impurity content of <20ppm, a thermal expansion coefficient of 3.9X10 -6 ～4.8×10 -6 /K, and a specific gravity of 1.6-1.9g/cm 3 .
  3. 3. The preparation method according to claim 1 or 2, wherein in step 1), before heating, the CVD furnace is evacuated and repressed twice in sequence, and the method comprises the steps of vacuumizing for the first time, introducing nitrogen for repressing, vacuumizing for the second time, and introducing hydrogen for repressing.
  4. 4. The method according to claim 3, wherein in step 1), the two successive evacuation steps include: the first vacuum pumping, namely pumping the gas in the CVD furnace until the vacuum degree reaches 1.0X10 -2 Kpa, and maintaining the pressure for 5-15min; Nitrogen repressing, namely filling N 2 until the pressure in the furnace is greater than 115Kpa, and maintaining the pressure for 5-15min; The second vacuumizing is repeated, namely the first vacuumizing is repeated; And (3) re-pressurizing by hydrogen, filling H 2 until the pressure in the furnace is greater than 115Kpa, and maintaining the pressure for 5-15min.
  5. 5. The process according to claim 1 or 2, wherein in step 1), The temperature rising speed is 3-7 ℃ per minute; heating and preserving heat for 20-40min.
  6. 6. The process according to claim 1, wherein in step 2), The volume ratio of the HCl to the hydrogen is 8-12:1; The cleaning time is 20-40min.
  7. 7. The process according to claim 1, wherein in step 3), The temperature rising speed is 3-7 ℃ per minute; The heat preservation time is 20-40min.
  8. 8. The method according to claim 1 or 6, wherein in step 3), the reaction time is 50 to 60 hours.
  9. 9. The process of claim 4, wherein the nitrogen has a purity of >99.999%, the hydrogen has a purity of >99.999%, the trichlorosilane has a purity of >98%, and the HCl has a purity of >99.999%.
  10. 10. Use of a CVD-SiC focus ring obtained by a method according to any one of claims 1-9 in a semiconductor etching apparatus.

Description

Preparation method and application of CVD-SiC focusing ring Technical Field The invention relates to the field of ceramic materials, in particular to a preparation method and application of a CVD-SiC focusing ring. Background The focus ring is an important ceramic part in a plasma etching apparatus, is an important part placed outside a wafer in direct contact with the wafer, and focuses plasma passing through the ring by applying a voltage to the ring, thereby focusing the plasma on the wafer to improve the uniformity of processing. Since the focus ring is in direct contact with the plasma in the vacuum reaction chamber, a material resistant to plasma erosion is required. The traditional focusing ring is made of silicon or quartz, and conductive silicon is used as a common focusing ring material, and the conductivity of the conductive silicon is almost similar to that of a silicon wafer, but the conductive silicon has the defect of poor etching resistance in fluorine-containing plasma, and the etching machine part material is often corroded seriously after being used for a period of time, so that the production efficiency of the conductive silicon is reduced seriously. Silicon carbide has conductivity similar to that of silicon and good ion etching resistance. With the miniaturization and promotion of integrated circuits, the demand and importance of integrated circuit manufacturing for etching processes are continuously increasing, and the power and energy of plasma for etching are continuously increasing, especially the required plasma energy in a Capacitive Coupling (CCP) plasma etching device is higher, so that the utilization rate of a focusing ring prepared from silicon carbide material is higher and higher. However, at present, the common silicon carbide ceramic material is mostly prepared by adopting reaction sintering (for example, patent CN 202510964800.3), and has the problems of low purity, low density, low thermal conductivity and the like, so that the use requirement of semiconductor etching equipment is difficult to meet. Therefore, it is necessary to develop a silicon carbide focusing ring with high purity, high density and high thermal conductivity so as to meet the use requirements of semiconductor etching equipment. Disclosure of Invention In order to solve the technical problems, the invention provides a preparation method and application of a CVD-SiC focusing ring. The CVD-SiC focusing ring prepared by adopting the CVD method has the characteristics of high purity, high density and high heat conductivity, and can meet the use requirement of semiconductor etching equipment. The specific technical scheme of the invention comprises the following steps: in a first aspect, the present invention provides a method for preparing a CVD-SiC focus ring, comprising the steps of: 1) The graphite ring is placed in a CVD furnace and heated to 1050-1150 ℃ under the condition of hydrogen. Graphite is very reactive at high temperatures and reacts readily with trace amounts of oxygen to form carbon monoxide or carbon dioxide, which not only corrodes the susceptor, but also introduces impurities into the reaction chamber. The introduction of hydrogen gas can protect the graphite base from oxidation. More importantly, the hydrogen can react with unstable and disordered carbon atoms on the graphite surface (methane is formed), so that the effect of 'cleaning' and 'stabilizing' the graphite surface is achieved, and carbon particles are prevented from being released in the subsequent deposition process to pollute the film. 2) HCl and hydrogen are introduced to clean the surface of the graphite ring. HCl can react with metal impurities and the like at high temperature efficiently, and gas phase products are generated to be discharged along with gas flow, but the corrosion to a high-quality graphite matrix is small (high-purity graphite is very resistant to HCl corrosion). This selectivity enables it to remove contaminants without severely damaging the base. 3) Heating, preserving heat, and then introducing process gas comprising trichloromethylsilane, hydrogen and HCl for reaction to obtain the graphite ring with the surface plated with the CVD-SiC layer. After the process gas is introduced, a CVD-SiC layer can be plated on the surface of the graphite ring, the main reaction formula is CH 3SiCl3 (g) to SiC(s) +3HCl (g), the actual reaction process is more complex, and the related intermediate steps mainly comprise: ① Decomposition of MTS: CH 3SiCl3 (g) → :SiCl2(g) + :CH2 (g) +HCl (g), which is a simplified representation of reactive radicals. In fact, MTS homolytic generates free radicals such as SiCl 3、·CH3. Reduction with H 2 H 2 also activates at high temperatures and reacts with MTS fragments to form more critical intermediates. The silicon reactive species ：CH3SiCl3(g) + H2(g) → :SiCl2(g) + CH4(g) + HCl(g);SiCl2（ dichlorosilane) is considered to be one of the most important silicon-containing vapor phase