Plasma etching method, plasma etching apparatus, control program, computer recording medium and recording medium having processing recipe recorded thereon
In a first step and a thirst step, etching gases are used which contain fluorocarbon gases having C/F atom number ratios higher than that in a second step. A hole is formed to a midpoint in a silicon oxide film in the first step, the hole is formed until a base SiN film begins to be exposed or immediately before it is exposed in the second step, and overetching is performed in the third step. This enables even a hole having a fine diameter and a high aspect ratio to be formed in an excellent shape.
1. A plasma etching method of forming a hole by an etching process in a silicon oxide film through a mask, comprising:
forming said silicon oxide film; and
conducting an etching process through said mask using etching gases containing fluorocarbon gasses, respectively, under a condition that the fluorocarbon gas used in an initial period of the etching process and the fluorocarbon gas used in a final period of the etching process contain no hydrogen and contain oxygen, and the C/F ratios of the fluorocarbon gasses used in the initial period and the final period are within a range of 5/8-2/3, and a condition that the fluorocarbon gas used in an intermediate period of the etching process contains no hydrogen and contains oxygen, and the C/F ratio of the fluorocarbon gas used in the intermediate period is 1/2 or lower so as to form said hole with a diameter of 0.13 μm or smaller and an aspect ratio of 15 or higher in said silicon oxide film,
wherein said mask is made of amorphous carbon.
2. A plasma etching method of forming a hole with a hole diameter of 0.13 μm or smaller in a silicon oxide film formed on a silicon nitride film, comprising:
a first step of etching the silicon oxide film to a midpoint using an etching gas containing C 4 F 6 or C 5 F 8 ;
after said first step, a second step of etching the silicon oxide film using an etching gas containing C 4 F 8 ; and
after said second step, a third step of performing overetching using an etching gas containing C 4 F 6 or C 5 F 8 .
3. The plasma etching method as set forth in claim 2 , wherein the etching gases used in said first step and third step comprise a mixed gas of C 4 F 6 or C 5 F 8 and an inert gas and oxygen, and
wherein the etching gas used in said second step comprises a mixed gas of C 4 F 8 and an inert gas and oxygen.
4. The plasma etching method as set forth in claim 2 ,
wherein the etching gases used in said first step through third step contain no hydrogen.
5. The plasma etching method as set forth in claim 2 ,
wherein said first step through third step are conducted via a mask made of amorphous carbon.