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CN-121985755-A - Method for removing unreacted nickel-platinum alloy in self-aligned silicide

CN121985755ACN 121985755 ACN121985755 ACN 121985755ACN-121985755-A

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a method for removing unreacted nickel-platinum alloy in self-aligned silicide, which comprises the following steps that a) a wafer with a metal layer on the surface is provided; the metal layer comprises nickel-platinum alloy; b) forming a porous titanium dioxide layer on the surface of the metal layer, c) removing the metal layer at normal temperature by adopting a photocatalytic reaction, d) removing the porous titanium dioxide layer by adopting a hydrogen peroxide complexing reaction, e) sequentially removing impurities, washing with water and drying the surface of the wafer to obtain the self-aligned silicide. Compared with the prior art, the method for removing the unreacted nickel-platinum alloy in the self-aligned silicide provided by the invention adopts specific process steps and conditions to realize overall better interaction, can remove the unreacted nickel-platinum alloy in the self-aligned silicide at normal temperature, avoids the influence of a high-temperature wet method on the thermal stability of the nickel-silicon compound, and does not lose the nickel silicide, thereby improving the process stability of the self-aligned silicide and further improving the product yield.

Inventors

  • CAO PING
  • LIU SUTAO

Assignees

  • 晶芯成(北京)科技有限公司
  • 合肥晶合集成电路股份有限公司

Dates

Publication Date
20260505
Application Date
20260409

Claims (10)

  1. 1. A method for removing unreacted nickel-platinum alloy from salicide, comprising the steps of: a) Providing a wafer with a metal layer on the surface, wherein the metal layer comprises nickel-platinum alloy; b) Forming a porous titanium dioxide layer on the surface of the metal layer; c) Removing the metal layer by adopting photocatalysis reaction at normal temperature; d) Removing the porous titanium dioxide layer by adopting a hydrogen peroxide complexation reaction; e) And sequentially removing impurities, washing and drying the surface of the wafer to obtain the self-aligned silicide.
  2. 2. The method of claim 1, wherein in step a), the thickness of the metal layer is 150nm to 200nm.
  3. 3. The method of claim 1, wherein in step b), the forming the porous titanium dioxide layer comprises atomic deposition.
  4. 4. The method of claim 3, wherein the atomic deposition process is performed at a deposition temperature of 350 ℃ to 450 ℃.
  5. 5. The method of claim 1, wherein in the step b), the thickness of the porous titanium dioxide layer is 50 nm-100 nm, and/or, The pore diameter of the porous titanium dioxide layer is 5 nm-10 nm.
  6. 6. The method for removing unreacted nickel-platinum alloy from salicide according to claim 1, wherein in step c), the process of removing the metal layer at normal temperature by using photocatalytic reaction specifically comprises: And an organic phase system of acetonitrile and dichloromethane is adopted, and the metal layer is dissolved at 15-35 ℃ under the illumination condition.
  7. 7. The method for removing unreacted nickel-platinum alloy from salicide according to claim 6, wherein the flow ratio of acetonitrile to dichloromethane in the organic phase system of acetonitrile and dichloromethane is 1 (0.5-2), and/or, The illumination condition specifically comprises 400mW/cm 2 ~600mW/cm 2 xenon lamp illumination.
  8. 8. The method for removing unreacted nickel-platinum alloy from salicide according to claim 1, wherein in step d), the process of removing the porous titanium dioxide layer by hydrogen peroxide complexation specifically comprises: And dissolving the porous titanium dioxide layer at 50-80 ℃ by adopting a mixed solution of dilute sulfuric acid and hydrogen peroxide.
  9. 9. The method for removing unreacted nickel-platinum alloy from salicide according to claim 8, wherein the concentration of the dilute sulfuric acid is 0.5M-1.5M, and/or, The concentration of the hydrogen peroxide is 20-40 wt percent and/or, The mass ratio of the dilute sulfuric acid to the hydrogen peroxide in the mixed solution of the dilute sulfuric acid and the hydrogen peroxide is 1 (1-4).
  10. 10. The method for removing unreacted nickel-platinum alloy from salicide according to claim 1, wherein in step e), the impurity removal process specifically comprises: And (3) processing the wafer at 15-35 ℃ by adopting a hydrochloric acid hydrogen peroxide solution, wherein the mass ratio of HCl to H 2 O 2 、H 2 O in the hydrochloric acid hydrogen peroxide solution is 1 (0.5-1.5) (5-10).

Description

Method for removing unreacted nickel-platinum alloy in self-aligned silicide Technical Field The invention relates to the technical field of semiconductor manufacturing, in particular to a method for removing unreacted nickel-platinum alloy in self-aligned silicide. Background The self-aligned silicide process is a key process in the semiconductor manufacturing technology and is mainly used for reducing the resistance of a source electrode, a drain electrode and a grid electrode structure so as to improve the performance and the working speed of a device, a nickel platinum film is deposited on the surface of the exposed silicon of the source electrode and the drain electrode, after a nickel silicide is generated through one-step rapid thermal annealing reaction, unreacted nickel platinum alloy is removed through a wet etching process, and finally, a metal silicide NiSi with a low resistance value is formed through a second step of rapid thermal annealing, which is shown in the figure 1. Currently, in the prior art, a single-chip wet etching device is generally used to remove unreacted nickel-platinum alloy by matching with high-temperature hydrogen sulfate solution or aqua regia solution, and the method can be seen in fig. 2. If the high-temperature hydrogen sulfate solution etches nickel platinum, the reaction temperature needs to reach more than 200 ℃, the requirement on equipment hardware is high, the thermal stability of the nickel silicide is poor, the high-temperature hydrogen sulfate solution releases heat along with the reaction, the actual temperature of a wafer is higher than 220 ℃, and the performance of the nickel silicide after the first rapid thermal annealing is affected. In addition, the high-temperature sulfuric acid hydrogen peroxide has a larger temperature difference from the ambient temperature, so that the surface temperature of the wafer tends to be reduced from the center to the edge in the wet etching process, which is unfavorable for the uniformity of wet etching (see FIG. 3), and the aqua regia is liable to damage nickel silicide (see FIG. 4). Disclosure of Invention Accordingly, the present invention aims to solve at least one of the technical problems in the related art to a certain extent. Therefore, the invention provides a method for removing unreacted nickel-platinum alloy in self-aligned silicide, which can remove the unreacted nickel-platinum alloy in self-aligned silicide at normal temperature, avoid the influence of a high-temperature wet method on the thermal stability of nickel-silicon compound and avoid the loss of nickel silicide. In order to solve the technical problems, the invention is realized as follows: According to one aspect of the present invention, there is provided a method for removing unreacted nickel-platinum alloy from salicide, comprising the steps of: a) Providing a wafer with a metal layer on the surface, wherein the metal layer comprises nickel-platinum alloy; b) Forming a porous titanium dioxide layer on the surface of the metal layer; c) Removing the metal layer by adopting photocatalysis reaction at normal temperature; d) Removing the porous titanium dioxide layer by adopting a hydrogen peroxide complexation reaction; e) And sequentially removing impurities, washing and drying the surface of the wafer to obtain the self-aligned silicide. In some embodiments, in step a), the thickness of the metal layer is 150nm to 200nm. In some of these embodiments, in step b), the means for forming the porous titanium dioxide layer comprises an atomic deposition process. In some embodiments, the atomic deposition process has a deposition temperature of 350 ℃ to 450 ℃. In some embodiments, in step b), the thickness of the porous titanium dioxide layer is 50nm to 100nm. In some embodiments, in step b), the pore size of the porous titanium dioxide layer is 5nm to 10nm. In some embodiments, in step c), the process of removing the metal layer at normal temperature by using a photocatalytic reaction specifically includes: And an organic phase system of acetonitrile and dichloromethane is adopted, and the metal layer is dissolved at 15-35 ℃ under the illumination condition. In some embodiments, the flow ratio of acetonitrile to dichloromethane in the organic phase system of acetonitrile to dichloromethane is 1 (0.5-2). In some embodiments, the illumination condition specifically comprises 400mW/cm 2~600mW/cm2 xenon lamp illumination. In some embodiments, in step d), the process of removing the porous titania layer by hydrogen peroxide complexation specifically includes: And dissolving the porous titanium dioxide layer at 50-80 ℃ by adopting a mixed solution of dilute sulfuric acid and hydrogen peroxide. In some embodiments, the concentration of the dilute sulfuric acid is 0.5 m-1.5 m. In some embodiments, the concentration of the hydrogen peroxide is 20wt% to 40wt%. In some embodiments, the mass ratio of the dilute sulfuric acid to the hydrogen peroxide in the mixed