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CN-121985740-A - Method for plasma enhanced chemical vapor deposition

CN121985740ACN 121985740 ACN121985740 ACN 121985740ACN-121985740-A

Abstract

A method of plasma enhanced chemical vapor deposition includes the steps of supporting a wafer on a wafer support within a reactor chamber, generating a plasma from acetylene gas, hydrogen gas, and argon gas using a high frequency RF power source, and depositing an amorphous hydrogenated carbon film on the wafer, wherein during the deposition, the reactor chamber pressure is in the range of 1-6 Torr, and wherein during the deposition, the wafer support temperature is between 200-350 degrees Celsius, such that the deposited amorphous hydrogenated carbon film provides a dielectric layer on the wafer that exhibits a low leakage current of less than 1.0E-07A/cm 2 and a high breakdown voltage of greater than 6MV/cm at an operating voltage of 2 MV/cm.

Inventors

  • K crook
  • W. Royle
  • E. Lucinska
  • M. Parfit

Assignees

  • SPTS科技有限公司

Dates

Publication Date
20260505
Application Date
20250620
Priority Date
20241031

Claims (20)

  1. 1. A method of plasma enhanced chemical vapor deposition comprising the steps of: supporting a wafer on a wafer support within a reactor chamber; Generating plasma from acetylene gas, hydrogen gas and argon gas using a high frequency RF power source, and Depositing an amorphous hydrogenated carbon film on the wafer; Wherein during said depositing the reactor chamber pressure is in the range of 1-6 Torr, and Wherein during said depositing, the wafer support temperature is between 200-350 degrees celsius; Such that the deposited amorphous hydrogenated carbon film provides a dielectric layer on the wafer that exhibits a low leakage current of less than 1.0E-07A/cm 2 and a high breakdown voltage of greater than 6MV/cm at an operating voltage of 2 MV/cm.
  2. 2. The method of claim 1, wherein the wafer support temperature is in the range of 225-325 degrees celsius during the depositing.
  3. 3. The method of claim 2, wherein the wafer support temperature is in the range of 250-300 degrees celsius during the depositing.
  4. 4. A method according to any preceding claim, wherein the plasma is generated using an RF power supply at 13.56 MHz.
  5. 5. The method of any preceding claim, wherein the plasma is generated using an RF driven showerhead and an electrically grounded wafer support.
  6. 6. A method according to any preceding claim, wherein the plasma is generated using an RF power supply providing a power of between 500-1500W.
  7. 7. The method of any preceding claim, wherein the reactor chamber pressure is in the range of 1.5-5 torr.
  8. 8. The process of any preceding claim, which is carried out in a capacitively coupled reactor.
  9. 9. The method of any preceding claim, wherein the acetylene gas is supplied to the reactor chamber at a flow rate in the range of 100-600 sccm.
  10. 10. The method of claim 8, wherein the acetylene gas is supplied to the reactor chamber at a flow rate in the range of 200-550 sccm.
  11. 11. The method of any preceding claim, wherein the hydrogen is supplied to the reactor chamber at a flow rate in the range of 100-600 sccm.
  12. 12. The method of claim 10, wherein the hydrogen is supplied to the reactor chamber at a flow rate in the range of 250-550 sccm.
  13. 13. The method of any preceding claim, wherein the argon is supplied to the reactor chamber at a flow rate in the range of 200-1000 sccm.
  14. 14. The method of claim 12, wherein the argon is supplied to the reactor chamber at a flow rate in the range of 300-900 sccm.
  15. 15. A method according to any preceding claim, wherein the wafer is a 300mm silicon wafer.
  16. 16. A method according to any preceding claim, wherein the deposited film has a thickness of between 150-1000 nm.
  17. 17. A method according to any preceding claim, wherein the deposited amorphous hydrogenated carbon film has a density of 1.6-1.8g/cc.
  18. 18. A plasma enhanced chemical vapor deposition system configured to perform the method of any one of claims 1-16, the system comprising: a reactor chamber; a gas inlet arranged to supply acetylene gas, hydrogen gas and argon gas to the reactor chamber; a wafer support configured to support a wafer within the reactor chamber; an RF power source is coupled to the reactor chamber.
  19. 19. The system of claim 17, wherein the wafer support is grounded and arranged for resistive heating to thereby heat the wafer.
  20. 20. The system of claim 17 or 18, further comprising a cooling mechanism associated with the wafer support and configured to cool the wafer.

Description

Method for plasma enhanced chemical vapor deposition Technical Field The present invention relates to a method of Plasma Enhanced Chemical Vapor Deposition (PECVD), and more particularly, to a method of depositing an amorphous hydrogenated carbon film on a wafer having excellent electrical isolation characteristics. The invention also relates to a PECVD apparatus configured to perform such a method. Background Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques may be used to deposit carbon films for a variety of purposes requiring carbon coatings. The film may include, for example, diamond-like carbon films, 2D carbon layer films, and polymer films. It should be understood that a "thin film" is a film having a thickness of no more than a few microns. Under most practical process parameters, the film tends to be disordered or amorphous. The film is generally defined as an amorphous carbon (a-C) or amorphous hydrogenated carbon (a-C: H) film. A dense amorphous hydrogenated carbon film (i.e., a density higher than 1.8 g/cc) may be used, for example, to provide a hard diamond-like carbon (DLC) protective layer on a substrate for advanced patterning applications, providing improved etch selectivity over conventional SiO 2 or SiN masks. For efficiency and ease of fabrication, it is preferred to deposit the film at a low temperature of less than 350 degrees celsius. It should be appreciated that the temperatures mentioned are wafer temperature/wafer support temperature. It would be advantageous to develop a suitable method of depositing an amorphous hydrogenated carbon film to be used as a dielectric film in an interconnect scheme. This would provide an alternative to conventional films such as SiO 2, siN, siC and SiCN films. For economic reasons, the film should be deposited at low temperatures and at acceptable deposition rates. Disclosure of Invention In a first aspect of the invention, a method of plasma enhanced chemical vapor deposition is provided. The method includes the steps of supporting a wafer on a wafer support within a reactor chamber, generating a plasma from acetylene gas, hydrogen gas, and argon gas using a high frequency RF power source, and depositing an amorphous hydrogenated carbon film on the wafer. During deposition, the reactor chamber pressure is in the range of 1-6 torr and the wafer support temperature is between 200-350 degrees celsius, such that the deposited amorphous hydrogenated carbon film provides a dielectric layer on the wafer that exhibits a low leakage current of less than 1.0E-07A/cm 2 and a high breakdown voltage of greater than 6MV/cm at an operating voltage of 2 MV/cm. The inventors have recognized that the electrical isolation characteristics of the deposited film must be sufficient for use as a dielectric film in an interconnect scheme. Accordingly, PECVD processes have been designed that use acetylene gas, hydrogen gas, and argon gas to deposit amorphous hydrogenated carbon films exhibiting low leakage current and high breakdown voltage at sufficiently rapid deposition rates. This has been achieved by high frequency power supplies, reactor chamber pressures in the range of 1-6 torr, and wafer temperatures between 200-350 degrees celsius. Lower platen/wafer support temperatures (< 350 degrees celsius) have been found to enable rapid deposition rates, whereas below a certain temperature, the electrical performance of the film has been found to deteriorate. Suitable temperatures for the platen that have been found to achieve acceptable deposition rates and still provide suitable electrical characteristics are in the range of 200-350 degrees celsius. Without being bound by any guess, it is proposed that amorphous hydrogenated carbon films deposited using C 2H2/Ar/H2 chemistry and high-frequency RF plasma at below 200 degrees celsius and above 350 degrees celsius cause structural changes in the film, which degrades the dielectric properties of the film. When compared to the films of the present invention, at lower temperatures, higher density films are deposited that contain excess sp2 bonding (determined by the FTIR sp3/sp2 ratio), which results in degraded dielectric properties, while at high temperatures hydrogen that can be incorporated into the film is insufficient to sufficiently passivate dangling bonds in the low density a-C matrix, again resulting in degraded dielectric properties. Optionally, the wafer temperature is in the range of 225-325 degrees celsius, more preferably in the range of 250-300 degrees celsius. The density of the film has been found to be dependent on temperature and, in addition, has been found to affect the electrical properties of the film. It has been found that a narrow range of densities corresponding to temperatures between 225-325 f, more preferably between 250-300 f, provides optimal electrical characteristics. The plasma is generated using a high frequency RF source (i.e., a power supply in excess of 1MHz, typically greater t