Method for forming superthin grid dielectric layer by using soft nitrogen-contained plasma

Abstract

A method for forming an ultra-thin gate dielectric layer with soft nitrogen-containing plasma. Nitriding the surface of the substrate with soft nitrogen-containing plasma is used to perform a pre-nitridation step. In this step, soft nitrogen-containing plasma is used to nitride the surface of the substrate. The plasma density of this soft nitrogen-containing plasma is about 10 9 -10 13 cm -3 . A thermal oxidation step is performed on the substrate to oxidize the surface of the substrate to form an ultra-thin gate dielectric layer on the surface of the substrate. The present invention utilizes soft nitrogen-containing plasma to uniformly nitride the surface of the substrate to control the thickness of the subsequently formed oxide layer. The method can avoid the problem that the surface structure of the substrate is damaged when nitrogen ions are directly implanted into the substrate by the conventional ion implantation method.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor element, in particular to a method for forming an ultra-thin gate dielectric layer with soft nitrogen-containing plasma. Background technique [0002] When the integration level required by semiconductor integrated circuit components is increasing, the demand for an ultra-thin gate dielectric layer with a high dielectric constant and a very low leakage current is also increasing. When the semiconductor process enters below 0.18 μm, the thickness of the gate dielectric layer will drop below 30 to 40 angstroms, and the dielectric layer below this thickness can be called an ultra-thin gate dielectric layer. Therefore, how to manufacture such a thin gate dielectric layer under the condition that the process window is shrinking day by day, and can take into account the uniformity of its thickness and better breakdown voltage resistance (breakdown resistance), It becomes an urgent problem t...

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Problems solved by technology

However, because the surface of the substrate is directly bombarded by the plasma, the structure of the surface of the substrate will be damaged, and because the kinetic energy of the plasma when it reaches the surface of the substrate is large, the implantation depth of nitrogen ions cannot make it possible to only nitride the surface of the substrate as much as possible. , in order to form an ultra-thin gate dielectric layer