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CN-120749075-B - Process method of shallow trench isolation structure

CN120749075BCN 120749075 BCN120749075 BCN 120749075BCN-120749075-B

Abstract

The invention relates to the technical field of semiconductors, in particular to a shallow trench isolation structure and a process method thereof. The shallow trench isolation structure comprises a trench and a filling structure, wherein the bottom of the trench is provided with a vertical side wall, the top of the trench is provided with a trapezoid opening, the trapezoid opening is gradually enlarged from outside to inside, the inclined side wall of the trapezoid opening is intersected with the vertical side wall, and the filling structure is filled in the trench. The process method of the shallow trench isolation structure comprises the steps of introducing process gas into a process chamber to excite and generate plasma, vertically bombarding a substrate, gradually adjusting the bombardment angle of the plasma, obliquely bombarding the bottom of the side wall of a trench, reducing radio frequency power, gradually adjusting the bombardment angle of the plasma, obliquely bombarding the top of the side wall of the trench, and filling insulating materials into the trench. The shallow trench isolation structure and the process method thereof provided by the invention have the advantages that the filling defect rate is low, and the reliability and the yield of the shallow trench isolation are obviously improved.

Inventors

  • JIAO FANG
  • JIA YANWEI

Assignees

  • 北京集成电路装备创新中心有限公司

Dates

Publication Date
20260512
Application Date
20250617

Claims (15)

  1. 1. The process method of the shallow trench isolation structure is characterized by comprising the following steps of: The method comprises the steps of a first etching step, wherein process gas is introduced into a process chamber to excite and generate plasma, and a substrate is subjected to vertical bombardment to form an initial shape of a groove, wherein the initial shape of the groove is U-shaped; a second etching step, gradually adjusting the bombardment angle of the plasma, and performing inclined bombardment on the bottom of the side wall of the groove to widen the bottom of the groove to form a vertical side wall; The third etching step, reducing radio frequency power, gradually adjusting the bombardment angle of the plasmas, and performing inclined bombardment on the top of the side wall of the groove to form a trapezoid opening; and filling an insulating material into the groove.
  2. 2. The process of claim 1, wherein the substrate is a silicon substrate; The first etching step may include one or more of fluorine-based gas, cl 2 , HBr, and O 2 , the second etching step may include one or more of fluorine-based gas, cl 2 , HBr, and O 2 , and/or the third etching step may include one or more of fluorine-based gas, cl 2 , HBr, and O 2 .
  3. 3. The process of claim 2, wherein in the first etching step, the fluorine-based gas comprises SF 6 ,SF 6 and O 2 in a volume ratio of 2:1-4:1, and/or Cl 2 、HBr、O 2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7); And/or, in the second etching step, the fluorine-based gas comprises SF 6 ,SF 6 and O 2 in a volume ratio of 2:1-4:1, and/or the Cl 2 、HBr、O 2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7); and/or in the third etching step, the fluorine-based gas comprises SF 6 ,SF 6 and O 2 in a volume ratio of 2:1-4:1, and/or Cl 2 、HBr、O 2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7).
  4. 4. The method of claim 1, wherein the second etching step comprises gradually increasing the angle of attack of the plasma, and performing oblique bombardment on the bottom of the sidewall of the trench from bottom to top to widen the bottom of the trench, thereby forming the vertical sidewall; and/or the third etching step comprises gradually increasing the bombardment angle of the plasma, and performing inclined bombardment on the top of the side wall of the groove from bottom to top to form the trapezoid opening.
  5. 5. The process according to claim 1, wherein in the second etching step, the rf power is 1200 to 1500w; and/or, in the third etching step, the radio frequency power is 200-300W.
  6. 6. The process of any one of claims 1-5, wherein the filling step comprises: A first filling step of generating an insulating material by high-density plasma chemical vapor deposition to fill the bottom of the trench; and a second filling step of generating the insulating material through fluidized chemical vapor deposition to fill the rest of the trench.
  7. 7. The process of claim 6, wherein in the first filling step, the deposition rate is 3-6 nm/min, the gas flow rate is 300sccm or more, and the process pressure is 5-10 mtorr; And/or in the second filling step, the deposition rate is 10-14 nm/min, the gas flow rate is 100-150 sccm, and the process pressure is 10-2000 mTorr.
  8. 8. The process of claim 6, wherein in the first filling step, the insulating material has a filling height of 40-60% of the trench depth.
  9. 9. The process of claim 6, wherein the insulating material is SiO 2 ; And/or the substrate is a silicon substrate.
  10. 10. The process of claim 9, wherein in the first filling step, the process gas comprises SiH 4 and O 2 , wherein the volume ratio of SiH 4 is 70-80%, and the volume ratio of O 2 is 20-30%; And/or in the second filling step, the process gas comprises SiH 4 and O 2 , wherein the volume ratio of SiH 4 is 70-80%, and the volume ratio of O 2 is 20-30%.
  11. 11. The process of any one of claims 1-5, wherein prior to the filling step, the process further comprises: and a deposition step, namely depositing a SiON layer on the inner wall of the groove.
  12. 12. The process of any one of claims 1-5, wherein after the filling step, the process further comprises: and an annealing step of performing plasma annealing in a nitrogen atmosphere.
  13. 13. The process of claim 12, wherein in the annealing step, the radio frequency power is 200-400 w, the process temperature is 400-500 ℃, and the process time is 20-40 s.
  14. 14. The process of any one of claims 1-5, wherein after the filling step, the process further comprises: and a planarization step, namely removing redundant parts of the top of the insulating material through chemical mechanical polishing so that the top of the insulating material is flush with the peripheral side structure of the groove.
  15. 15. The process of any one of claims 1-5, wherein prior to the first etching step, the process further comprises: and a masking step of depositing a hard mask layer on the substrate.

Description

Process method of shallow trench isolation structure Technical Field The invention relates to the technical field of semiconductors, in particular to a shallow trench isolation structure and a process method thereof. Background The LOCOS (Local Oxidation of Silicon) technology is widely applied in the integrated circuit manufacturing process above 0.35 microns, has long development history and mature process, however, the technology adopts a field oxidation process, the depth of an oxide film and the beak effect generated by oxidation in the active area at the edge of a field region, so that the further application of the technology is limited. As feature sizes of semiconductor devices continue to shrink, isolation regions between devices also need to shrink accordingly, and STI (shallow trench isolate, shallow trench isolation) techniques are often applied to replace LOCOS techniques to accommodate deep submicron processes below 0.35 microns. However, the shallow trench isolation structure in the related art has the problems of high filling defect rate, low reliability and the like. Disclosure of Invention The invention aims to provide a shallow trench isolation structure and a process method thereof, which are used for solving the technical problems of high filling defect rate and low reliability of the shallow trench isolation structure in the prior art. The shallow trench isolation structure provided by the invention comprises a trench and a filling structure. The bottom of the groove is provided with a vertical side wall, the top of the groove is provided with a trapezoid opening, the trapezoid opening is gradually enlarged from outside to inside, the inclined side wall of the trapezoid opening is intersected with the vertical side wall, and the filling structure is filled in the groove. Preferably, as an implementation manner, the ratio of the difference of the width of the big end and the width of the small end of the trapezoid opening is 20-30%; and/or the inclination angle of the inclined side wall is 10-30 degrees. Preferably, as an implementation manner, the vertical side wall and the bottom wall are smoothly transited through an arc corner. Preferably, as an implementation manner, the radius of curvature of the arc-shaped corner is 5-20 nm. Preferably, as an embodiment, a SiON layer is attached to the inner wall of the trench. The invention provides a process method of a shallow trench isolation structure, which comprises the following steps: The method comprises the steps of a first etching step, wherein process gas is introduced into a process chamber to excite and generate plasma, and a substrate is subjected to vertical bombardment to form an initial shape of a groove, wherein the initial shape of the groove is U-shaped; A second etching step, gradually adjusting the bombardment angle of the plasma, and performing inclined bombardment on the bottom of the side wall of the groove to widen the bottom of the groove, so as to form the vertical side wall; The third etching step, reducing radio frequency power, gradually adjusting the bombardment angle of the plasmas, and performing inclined bombardment on the top of the side wall of the groove to form the trapezoid opening; and filling an insulating material into the groove. Preferably, as an implementation manner, the substrate is a silicon substrate. The first etching step may include one or more of fluorine-based gas, cl 2, HBr, and O 2, the second etching step may include one or more of fluorine-based gas, cl 2, HBr, and O 2, and/or the third etching step may include one or more of fluorine-based gas, cl 2, HBr, and O 2. Preferably, as an implementation manner, in the first etching step, the fluorine-based gas includes SF 6,SF6 and O 2 in a volume ratio of 2:1-4:1, and/or Cl 2、HBr、O2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7); And/or, in the second etching step, the fluorine-based gas comprises SF 6,SF6 and O 2 in a volume ratio of 2:1-4:1, and/or the Cl 2、HBr、O2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7); and/or in the third etching step, the fluorine-based gas comprises SF 6,SF6 and O 2 in a volume ratio of 2:1-4:1, and/or Cl 2、HBr、O2 in a volume ratio of (0.8-1.2): (1.8-2.2): (0.4-0.7). Preferably, as an implementation manner, the second etching step includes gradually increasing the bombardment angle of the plasma, and performing inclined bombardment on the bottom of the side wall of the trench from bottom to top to widen the bottom of the trench, so as to form the vertical side wall; and/or the third etching step comprises gradually increasing the bombardment angle of the plasma, and performing inclined bombardment on the top of the side wall of the groove from bottom to top to form the trapezoid opening. Preferably, as an implementation manner, in the second etching step, the radio frequency power is 1200-1500 w; and/or, in the third etching step, the radio frequency power is 200-300W. Preferably, as an implementatio