Method of forming insulation film by modified PEALD
A method of forming an insulation film by alternating multiple times, respectively, a process of adsorbing a precursor onto a substrate and a process of treating the adsorbed surface using reactant gas and a plasma, wherein a plasma is applied in the process of supplying the precursor.
1. A method of forming an insulation film by plasma enhanced atomic layer deposition (PEALD), comprising in the following sequence:
(i) introducing a precursor without a reactant gas into a reaction space where a substrate is placed, which precursor is an aminosilane compound;
(ii) exciting the precursor in the reaction space with a plasma by applying a first RF power to the reaction space for adsorbing the precursor on a surface of the substrate;
(iii) adsorbing the plasma-treated precursor onto the surface of the substrate;
(iiia) purging the reaction space between steps (iii) and (iv) without RF power;
(iv) introducing a reactant gas without a precursor to the reaction space and exciting the reactant gas with a plasma by applying a second RF power to the reaction space to treat the precursor-adsorbed surface with the excited reactant gas to form and fix a film on the surface, wherein the reactant gas is NO 2 , O 2 , H 2 , CO 2 , N 2 O, N 2 and/or NH 3 ,
wherein steps (i) to (iv) constitute one cycle of PEALD, wherein the first RF power is lower than the second RF power wherein the first RF power is less than 50 W so as to maintain a step coverage of the film at 90% or higher as measured for an aspect ratio (depth/opening width) of 3, and the second RF power is 100 W or more; and
(v) repeating the one cycle multiple times until an atomic layer of a desired thickness is obtained.
2. The method according to claim 1 , wherein no reactant gas is supplied in steps (i) to (iii).
3. The method according to claim 1 , wherein the insulation film is constituted by a silicon compound.
4. The method according to claim 3 , wherein the silicon compound is SiO, SiN, SiC, SiON, SiCON, SiCO, SiBN, SiBO or SiCN.
5. The method according to claim 1 , wherein the first RF power is less than 1/10 of the second RF power.
6. The method according to claim 1 , wherein the first RF power is less than 0.07 W/cm 2 per area of the substrate.
7. The method according to claim 1 , wherein the process pressures in steps (i) to (iv) are in a range of 50 to 2000 Pa.
8. The method according to claim 1 , wherein the plasmas in steps (ii) and (iv) are generated in a gap between capacitively-coupled parallel plate electrodes.
9. The method according to claim 1 , wherein in the one cycle, a duration of step (ii) is 0.2 to 5 seconds, a duration of step (iv) is 0.2 to 5 seconds, and an interval between step (ii) and step (iv) is 0 to 5 seconds.
10. The method according to claim 1 , wherein the surface has a trench, and the method further comprises, prior to step (i), setting a target step coverage of the insulation film at the trench, and setting the first value of RF power according to the target step coverage based on a predetermined correlation between a value of RF power and step coverage for the insulation film.