Method of forming fine patterns in semiconductor device and method of forming gate using the same

1. A method of forming a gate, the method comprising:

forming a plurality of sidewall buffer patterns over a gate insulating layer formed on a substrate, wherein the plurality of sidewall buffer patterns are spaced apart from each other by a predetermined distance;

depositing a sidewall layer on the sidewall buffer patterns and directly on the gate insulating layer;

etching the sidewall layer such that sidewall patterns remain on sidewalls of the sidewall buffer patterns, wherein during the step of etching the sidewall layer, a critical dimension (CD) of a gate pattern is determined by a distance between the sidewall patterns, wherein the distance between the sidewall patterns is determined by both a width of a sidewall pattern of the sidewall patterns and a height of a sidewall buffer pattern of the sidewall buffer patterns;

forming a gate by depositing a conductive layer on the gate insulating layer between the sidewall patterns; and

etching all the sidewall buffer patterns and the sidewall patterns,

wherein the sidewall buffer patterns are formed of a first insulator and the sidewall layer is formed of a second insulator, and

wherein the gate insulating layer remains after etching the sidewall buffer patterns and the sidewall patterns.

2. The method according to claim 1 , wherein the step of forming the plurality of sidewall buffer patterns includes:

depositing a sidewall buffer layer over the gate insulating layer formed on the substrate;

patterning a photoresist layer after coating the photoresist layer on the sidewall buffer layer; and

etching the sidewall buffer layer using the patterned photoresist layer as an etch mask.

3. The method according to claim 1 , wherein, during the step of forming the plurality of sidewall buffer patterns, the sidewall buffer pattern is formed of a material having superior etch selectivity to the etch selectivity of the conductive layer.

4. The method according to claim 1 , wherein, during the step of forming the plurality of sidewall buffer patterns, the sidewall buffer pattern is formed of one of an oxide material and a nitride material.

5. The method according to claim 1 , wherein, during the step of depositing the sidewall layer, the sidewall pattern is formed of a material with superior etch selectivity than the conductive layer.

6. The method according to claim 1 , wherein, during the step of depositing the sidewall layer, the sidewall pattern is formed of one of an oxide material and a nitride material.

7. The method according to claim 1 , further comprising, after the step of depositing the sidewall layer, planarizing the sidewall layer.

8. The method according to claim 1 , wherein, during the step of etching the sidewall layer, the sidewall layer is etched such that the distance between the sidewall patterns remaining on the sidewalls of the sidewall buffer patterns maintains the critical dimension (CD) of a gate.

9. The method according to claim 1 , wherein, during the step of etching the sidewall layer, the distance between the sidewall patterns is shortened to be a critical dimension of a fine gate as the sidewall pattern becomes wide with the increase of the height of the sidewall buffer pattern.

10. The method according to claim 1 , further comprising, after the step of depositing the conductive layer, planarizing the conductive layer.