United Microelectronics Corp.

Hsi-Chieh Chen

Sheng-Hao Lin

Lu-Min Liu

Ping-Ho Lo

A method of fabricating a shallow trench isolation is disclosed. First, a pad oxide layer and a polysilicon layer are formed on a silicon substrate. The pad oxide layer and the polysilicon layer are etched to expose parts of the substrate. Then the exposed parts of the substrate are oxidized to form an oxide layer. Next, the oxide layer is etched back to form an oxide spacer on the side wall of the polysilicon. Then, a shallow trench is formed by etching the partly exposed substrate. Next, a dielectric layer is formed to fill the shallow trench and then etched back by CMP to stop on the polysilicon layer. Finally, the pad oxide layer and the polysilicon layer are removed. As a result, oxide spacers on the side wall of the shallow trench are formed to eliminate the kink-effect.

Method of fabricating shallow trench isolation

A method of fabricating kink-effect-free shallow trench isolations is presented in this invention. First, a layer of silicon oxide and a layer of polysilican are sequentially deposited on a substrate, and then shallow trenches are formed, next thermal oxidation is performed to grow a passivation oxide layer on the exposed silicon, and then, a dielectric layer is formed to fill into the shallow trench. Finally, the dielectric layer on the active area is removed by using chemical mechanical polishing and the polysilicon layer provides for the etching end point. The level of shallow trench is higher than the level of active area as soon as stop polishing, because the polysilicon layer is polished faster than dielectric layer. It provides the passivation oxide on the sidewall of shallow trench to form spacers of the active area after removing the polysilicon of active area. It can provide a perfect shallow trench after an oxidation and etching process to avoid the kink effect.

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Taipei, Taiwan

Hsi-Chieh Chen