Development Of ESD Diode Deep Trench Isolation Technology Process Platform

With the rapid development of semiconductor manufacturing processes,the Size of integrated circuit processes is getting smaller,and the effective area of Silicon wafers is more valuable,and deep trench isolation technology has begun to be widely used in the isolation process of special devices.The deep trench isolation technology uses an anisotropic etching equipment to etch deep trenches with a specific shape in the Silicon wafer isolation area,and then uses a diffusion process to fill the deep trench to achieve the purpose of forming deep trench isolation on the Silicon wafer.The most critical process of deep trench isolation technology is deep trench etching.The biggest technical difficulty of deep trench etching is that it is difficult to obtain a vertical flat sidewall profile,so the development of deep trench etching platforms becomes extremely important.A new Silicon deep trench etching technology with vertical flat sidewall is proposed.Based on low cost RIE dry etching equipment from Applied Materials P5000,use NF₃,HBr and O₂ as process gas.NF₃,HBr and O₂ served as reaction and Side-wall passivation gas respectively,and HBr served as auxiliary gas to enhance the Si O₂ mask selection ratio and Side-wall flatness.By studying the effects of process parameters such as RF power,vacuum pressure,gas mixture ratio,magnetic field intensity,backing Helium pressure and temperature on deep trench profile,and analyzing the relevant mechanisms,an optimized process platform was obtained,and the following results were achieved:Etch rate greater than 1.2?m/min,trench width less than 2.0?m,trench depth above 12.0?m and lateral etching less than 0.2?m.After the silicon deep trench was backfilled with polycrystalline silicon,it was successfully used as device isolation for ESD diodes,reducing leakage current and parasitic capacitance,and increasing the effective chip area.