Etching method
A method of selectively etching a first region R 1 made of silicon oxide with respect to a second region R 2 made of silicon nitride by performing a plasma processing upon a processing target object is provided. The processing target object has the second region R 2 forming a recess; the first region R 1 configured to fill the recess; and a mask MK provided on the first region R 1 . The method includes a first process of generating plasma of a processing gas containing a fluorocarbon gas, and a second process of etching the first region with radicals of fluorocarbon contained in a deposit. In the second process, a high frequency power contributing to the generating of the plasma is applied in a pulse shape, and these processes are repeated.
1. An etching method comprising: a) providing a target object in a processing chamber, the target object including a first region, a second region and a mask, the first region being made of a first silicon-containing material, the second region being made of a second material different from the first silicon-containing material, the first region being disposed on the second region, the second region having a recess, the recess being filled with the first region, the mask being disposed on the first region, the mask having an opening, the opening having a width larger than a width of the recess; b) generating a plasma from a fluorocarbon containing gas supplied into the processing chamber to form a fluorocarbon containing deposit on the target object; and c) applying a pulsed power to the processing chamber, thereby causing the first region to be etched with fluorocarbon radicals in the fluorocarbon containing deposit; and d) repeating b) and c), wherein the pulsed power includes a first power having a first frequency ranging from 27 MHz to 100 MHz and a second power having a second frequency ranging from 400 kHz to 40 MHz, wherein, in c), the pulsed power is generated by applying the first power for plasma generation to an upper electrode provided above the target object within the processing chamber; applying the second power for ion attraction to a lower electrode provided under the target object; and performing a modulation of alternately switching a period during which the first power and the second power are ON and a period during which the first power and the second power are OFF.
2. The etching method of claim 1 ,
wherein, in c), the first region is etched by a processing gas which does not substantially contain oxygen.
3. The etching method of claim 1 ,
wherein, in b), the plasma is generated from a processing gas containing the fluorocarbon containing gas, an oxygen-containing gas and an inert gas.
4. The etching method of claim 1 ,
wherein a ratio (duty ratio) of the period during which the pulsed power is ON to a pulse cycle is in a range from 10% to 70%.
5. The etching method of claim 1 ,
wherein a ratio (duty ratio) of the period during which the power of the pulse shape is ON to a pulse cycle is in a range from 50% to 60%.
6. The etching method of claim 1 ,
wherein the first silicon-containing material is silicon oxide, and the second material is silicon nitride.
7. An etching method comprising: providing a target object in a processing chamber, the target object including a first region, a second region and a mask, the first region being made of a first silicon-containing material, the second region being made of a second material different from the first silicon-containing material, the first region being disposed on the second region, the second region having recess, the recess being filled with the first region, the mask being disposed on the first region, the mask having an opening, the opening having a width larger than a width of the recess; performing a first sequence including a first process and a second process, the first process comprising generating, while applying a first power having a first frequency ranging from 27 MHz to 100 MHz to the processing chamber, a plasma from a fluorocarbon containing gas supplied into the processing chamber to form a fluorocarbon containing deposit on the target object, the second process comprising applying a pulsed power to the processing chamber, thereby causing the first region to be etched with fluorocarbon radicals in the fluorocarbon containing deposit; and performing a second sequence including the first process and the second process, wherein the pulsed power includes the first power and a second power having a second frequency ranging from 400 kHz to 40 MHz, wherein the first sequence is performed at a timing when the second region is exposed, and in the first sequence and the second sequence, the first process and the second process are repeated, herein, in the second sequence, the pulsed power is generated by applying the first power for plasma generation to an upper electrode provided above the target object within the processing chamber; applying the second power for ion attraction to a lower electrode provided under the target object; and performing a modulation of alternately switching a period during which the first power and the second power are ON and a period during which the first power and the second power are OFF.
8. The etching method of claim 7 ,
wherein the power in the first process is a continuous wave.
9. The etching method of claim 7 ,
wherein the power in both the first process and the second process is a pulse wave.
10. The etching method of claim 9 ,
wherein, in the second process, a bias power is applied, and the pulsed power and the bias power are applied synchronously.
11. The etching method of claim 7 , further comprising:
a third sequence including the first process and the second process,
wherein a bias power applied in the third sequence is larger than bias powers applied in the first sequence and the second sequence.
12. The etching method of claim 7 ,
wherein a bias power applied in the second sequence is smaller than a bias power applied in the first sequence.
13. The etching method of claim 7 ,
wherein an etching time in the second sequence is set to be longer than an etching time in the first sequence.
14. The etching method of claim 7 ,
wherein an etching amount of the first region in the first sequence is less than an etching amount of the first region in the second sequence.
15. The etching method of claim 7 ,
wherein a processing time of the first sequence is shorter than a processing time of the second sequence.
16. The etching method of claim 7 ,
wherein, in the first process, the deposit is reduced while the deposit is formed.
17. The etching method of claim 16 ,
wherein, in the first process, a reduction rate of the deposit is equal to or less than 1 nm/sec.
18. The etching method of claim 7 ,
wherein the second process is performed by a processing gas which does not substantially contain oxygen.