| abstract |
An MLR (multilayer resist) 3 is formed on a BPSG layer 2 on top of a silicon wafer 1, then dry etched using an etching gas 8 to form a contact hole 2a on the BPSG layer 2. Next, the polymer residues 9a and 9b adhering to the side walls of the contact hole 2a and the surface of the BPSG layer 2 are subjected to a cleaning treatment using a cleaning treating liquid that contains 0.04-0.12 wt% hydrogen fluoride, thereby removing the polymer residues 9a nand 9b. n During etching the presence of the polymer residue layer 9 prevents etching in the horizontal direction, thereby allowing the formation of a highly precise contact hole 2a. In addition, because the treating liquid has the composition described above, the aforementioned polymer residues 9a and 9b are removed, thereby avoiding any degradation of the electrical characteristics. In addition, corrosion of the side walls of the contact hole due to the cleaning treating liquid is prevented, thereby maintaining the high level of contact hole precision. As a result good electrical characteristics are ensured even if the structure has an ultrafine-pitch pattern. |