Influence of step height of plasma surface processor on polysilicon gate etching

• Categories:Company Dynamics
• Author:plasma cleaning machine-surface treatment equipment-CRF plasma machine-Sing Fung Intelligent Manufacturing
• Origin:
• Time of issue:2020-12-02
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(Summary description)In addition to the effect of the surface etching of plasma surface processor on the size of polysilicon gate, the surface topography fluctuation caused by shallow groove isolation also has a significant effect on the size of polysilicon gate. The height of shallow grooved isolated steps characterizes the surface morphology of the wafer before polysilicon growth. Due to the flat growth of the furnace tube polysilicon, the positive step height (the upper surface of the shallow trench isolation silicon is higher than the bulk silicon active region) will lead to the thickening of the polysilicon near the shallow trench isolation region, thus affecting the side wall Angle of the polysilicon gate. At the positive step height, after the main etching step of the plasma surface processor polysilicon gate etching, the side wall of the polysilicon gate located in the isolation zone of the shallow groove is obviously more inclined than the active zone, and the characteristic size is also obviously larger than the active zone.   Even if the plasma surface treatment machine's main etching step USES gases that produce less polymerization byproducts, vertical gate wall cannot be formed in the shallow trench isolation zone, and this difference in side wall will remain until the etching is complete. The side wall Angle of the polysilicon gate near the shallow groove isolation is only 86°, while the side wall Angle of the polysilicon gate located in the center of the active region reaches 89°. Therefore, the difference of polysilicon film thickness leads to the difference of gate side wall Angle, while the difference of gate side wall Angle leads to the difference of feature size.   Under different characteristic sizes of active zones, the isolated step height of shallow trench will be different. The load caused by the difference of density in the source area during the chemical mechanical grinding after the shallow groove isolation will lead to the difference of step height, which will affect the difference of characteristic size and Angle of polycrystalline silicon etching. The relationship between the polysilicon height and the step height under different width of the fed region shows that the size of the fed region is closely related to the step height during gate etching. With different width of the source region, the characteristic dimensions of the optical polysilicon and the polysilicon with surface morphology before and after exposure and etching show that the width of the source region is different, and the etching deviation of the plasma surface processor will also be different.