Method for etching multilayer film
A method according to an exemplary embodiment includes: (a) etching an upper magnetic layer by plasma generated within a processing container, the etching of the upper magnetic layer being terminated on a surface of an insulating layer; (b) removing a deposit formed on a surface of the mask and the upper magnetic layer by etching the upper magnetic layer, by the plasma generated within the processing container; and (c) etching the insulating layer by the plasma generated within the processing container. In the step of removing the deposit, the support structure that holds a processing target is inclined and rotated, and a pulse-modulated DC voltage as a bias voltage for ion attraction is applied to the support structure.
1. A method of etching a multilayer film of a processing target using a plasma processing apparatus,
the processing target including an underlying layer, a lower magnetic layer provided on the underlying layer, an insulating layer provided on the lower magnetic layer, an upper magnetic layer provided on the insulating layer, and a mask provided on the upper magnetic layer,
the plasma processing apparatus including a processing container, a gas supply system that supplies a rare gas and a hydrogen-containing gas into the processing container, a high frequency power supply for plasma generation, and a support structure that supports the processing target, and
the method comprising:
sequentially etching the upper magnetic layer, the insulating layer, the lower magnetic layer and the underlying layer by plasma generated from the rare gas supplied into the processing container while modifying, by the hydrogen-containing gas, one of the upper magnetic layer, the insulating layer, the lower magnetic layer and the underlying layer that is being etched, and wherein the etching of the upper magnetic layer is terminated on a surface of the insulating layer, the etching of the insulating layer is terminated on a surface of the lower magnetic layer, and the etching of the lower magnetic layer is terminated on a surface of the underlying layer,
wherein each etching step generates a deposit formed on a surface of the processing target,
wherein after each step of etching the upper magnetic layer, the insulating layer, the lower magnetic layer, and the underlying layer, the sequentially etching comprises:
a step of rotating the support structure about a first axis passing horizontally through the support structure to tilt the support structure at a predetermined angle with respect to a second axis extending orthogonal to the first axis, while simultaneously rotating the processing target about the second axis such that ions of the rare gas intersect at an incident direction with the deposit formed on the surface of the processing target, thereby removing the deposit, and
wherein the step of removing the deposit, a pulse-modulated DC voltage as a bias voltage for ion attraction is applied to the support structure,
further comprising:
after the step of removing the deposit generated during the step of etching the upper magnetic layer and before the step of etching the insulating layer, transferring the processing target to a film forming apparatus and forming an insulating film on a surface of the processing target; and
after the step of forming the insulating film, etching a top surface of the mask and a top surface of the insulating layer in the plasma processing apparatus by plasma generated from one of a hydrofluorocarbon gas and a fluorocarbon gas.
2. The method of claim 1 , wherein the step of removing the deposit, plasma is generated from the rare gas comprising an atomic number larger than an atomic number of argon.
3. The method of claim 1 , wherein the steps of etching the upper magnetic layer and removing of the deposit are alternately repeated.
4. The method of claim 1 , wherein the pulse-modulated DC voltage has a period having a high level and a period having a low level in one cycle, and a duty ratio of the DC voltage, which is a ratio of the period having the high level in one cycle, ranges from 10% to 90%.
5. The method of claim 1 , wherein the step of etching the upper magnetic layer, plasma is generated from the rare gas comprising an atomic number larger than an atomic number of argon, and the pulse-modulated DC voltage as a bias voltage for ion attraction is applied to the support structure.
6. The method of claim 5 , wherein the step of etching the insulating layer, plasma is generated from the rare gas comprising an atomic number larger than the atomic number of argon, and a pulse-modulated DC voltage higher than the DC voltage applied to the support structure in the step of etching the upper magnetic layer or a high-frequency bias power is applied to the support structure.
7. The method of claim 1 , wherein the step of etching the underlying layer, plasma is generated from the rare gas, and a pulse-modulated DC voltage higher than the DC voltage applied to the support structure in the step of etching the upper magnetic layer or a high-frequency bias power is applied to the support structure.
8. The method of claim 7 , wherein the step of etching the underlying layer includes setting the support structure to a non-inclined first state, and setting the support structure to an inclined and rotary second state.
9. The method of claim 8 , wherein the step of setting the support structure to the inclined and rotary second state, the processing target is simultaneously rotated about the second axis.
10. The method of claim 7 , wherein the step of etching the underlying layer includes a first step of generating plasma of a processing gas containing a first rare gas having an atomic number larger than an atomic number of argon, and a second step of generating plasma of a processing gas containing a second rare gas having an atomic number smaller than the atomic number of argon.
11. The method of claim 10 , wherein the step of etching the underlying layer, a high-frequency bias power is supplied to the support structure.
12. The method of claim 10 , wherein at least one of the first step and the second step, the support structure is inclined and rotated.
13. The method of claim 10 , wherein the first rare gas includes a Kr gas, and the second rare gas includes a Ne gas.
14. The method of claim 1 , wherein the predetermined angle is set in a range of 0° to 60°.
15. The method of claim 1 , wherein the pulse-modulated DC voltage is set in a range of 0 V to 1200 V.
16. The method of claim 1 , wherein a modulation frequency of the pulse-modulated DC voltage is 400 kHz.