Plasma etching method
First Claim
1. A plasma etching method in which a processing gas is introduced into a processing room housing a substrate, an RF power is applied across opposite electrodes to cause the processing gas to discharge, thereby generating a plasma, and a first layer supported by said substrate is etched by using the plasma in preference to a second layer supported by said substrate and consisting of a material different from that of said first layer,wherein said first layer consists essentially of SiO2 while second layer consists essentially of a material selected from a group consisting of SiN, Si, Al, and TiN, the processing gas contains C4 F8 and CO, and progress of dissociation of C4 F8 is controlled, using a discharge duration of each part of the processing gas as a parameter, in order to set an etching selection ratio of said first layer to said second layer.
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Accused Products
Abstract
A plasma etching apparatus has a lower electrode for supporting a semiconductor wafer in a processing room, an upper electrode opposite to the lower electrode, and an RF power supply for applying an RF power across the upper and lower electrodes. An SiN layer as an underlayer having a shoulder portion, and an SiO2 layer covering the SiN layer are disposed on the wafer. A contact hole is formed in the SiO2 layer by etching so as to expose the shoulder portion of the SiN layer. A processing gas contains C4 F8 and CO. To set the etching selection ratio of SiO2 /SiN, the discharge duration of each part of the processing gas is used as a parameter. The progress of dissociation of C4 F8 is controlled by selecting the discharge duration. The discharge duration is determined by the residence time of each part of the processing gas and the application time of an RF power.
137 Citations
18 Claims
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1. A plasma etching method in which a processing gas is introduced into a processing room housing a substrate, an RF power is applied across opposite electrodes to cause the processing gas to discharge, thereby generating a plasma, and a first layer supported by said substrate is etched by using the plasma in preference to a second layer supported by said substrate and consisting of a material different from that of said first layer,
wherein said first layer consists essentially of SiO2 while second layer consists essentially of a material selected from a group consisting of SiN, Si, Al, and TiN, the processing gas contains C4 F8 and CO, and progress of dissociation of C4 F8 is controlled, using a discharge duration of each part of the processing gas as a parameter, in order to set an etching selection ratio of said first layer to said second layer.
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7. A plasma etching method in which a processing gas is introduced into a processing room housing a substrate, an RF power is applied across opposite electrodes to cause the processing gas to discharge, thereby generating a plasma, and a first layer supported by said substrate is etched by using the plasma in preference to a second layer supported by said substrate and consisting of a material different from that of said first layer,
wherein said first layer consists essentially of SiO2 while said second layer consists essentially of a material selected from a group consisting of SiN, Si, Al, TiN, W, WSi, and TiSi, the processing gas contains C4 F8 and CO, and a density ratio of C2 F4 and CF3, which are generated upon dissociation of C4 F8, is controlled, using a discharge duration of each part of the processing gas as a parameter, in order to set an etching selection ratio of said first layer to said second layer.
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13. A plasma etching method using a plasma etching apparatus in which a first layer supported by a substrate is etched in preference to a second layer supported by said substrate and consisting of a material different from that of said first layer,
wherein said apparatus comprises a first electrode for supporting said substrate in a processing room, a second electrode opposite to said first electrode in said processing room, and an RF power supply for applying an RF power across said first and second electrodes, and wherein said first layer consists essentially of SiO2 while said second layer consists essentially of a material selected from a group consisting of SiN, Si, Al, TiN, W, WSi, and TiSi, the processing gas contains C4 F8 and CO, said method comprising the steps of: -
selecting a value for a discharge duration of each part of a processing gas as a parameter in order to set an etching selection ratio of said first layer to said second layer, a density ratio of C2 F4 to CF3, which are generated upon dissociation of C4 F8, being controlled by changing the discharge duration; setting said plasma etching apparatus in accordance with the selected value of the parameter; supporting said substrate by said first electrode; supplying the processing gas into said processing room while exhausting said processing room, the processing gas containing C4 F8 and CO; applying the RF power across said first and second electrodes to convert the processing gas into a plasma; and processing said first and second layers using the plasma. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification