Method for etching vias
View Patent ↗An improved method for etching a substrate that reduces the formation of pillars is provided by the present invention. In accordance with the method, the residence time of an etch gas utilized in the process is decreased and the power of an inductively coupled plasma source used to dissociate the etch gas is increased. A low bias RF voltage is provided during the etching process. The RF bias voltage is ramped between different bias levels utilized during the etch process. An inductively coupled plasma confinement ring is utilized to force the reactive species generated in the inductively coupled plasma source over the surface of the substrate. These steps reduce or eliminate the formation of pillars during the etching process.
1. An improved method for forming via holes in a GaAs substrate comprising the steps of:
forming a mask layer on the GaAs substrate;
placing said GaAs substrate in an inductively coupled plasma processing system;
introducing high Cl 2 flows into the processing system;
etching via holes in the GaAs substrate by increasing a power level of the inductively coupled plasma processing system to more fully dissociate the high Cl 2 flows;
removing the GaAs substrate from the plasma processing system; and
stripping said mask layer from said GaAs substrate.
2. The method of claim 1 wherein said processing system having an inductively coupled plasma confinement ring.
3. The method of claim 1 further comprising the step of initiating the etch using a low RF bias power.
4. The method of claim 1 further comprising the step of decreasing a residence time of an etch gas used during an etching process to prevent the formation of pillars.
5. The method of claim 1 comprising the step of ramping the RF power between different levels between process steps to eliminate pillar formation during the etch process.
6. The method of claim 1 wherein the etch process further comprises an ion assisted etch process.
7. An improved method for forming via holes in a GaAs substrate using an inductively coupled plasma source, the method comprising the steps of:
forming a mask layer on the GaAs substrate;
placing said GaAs substrate in an inductively coupled plasma processing system;
introducing high Cl 2 flows into the processing system;
etching via holes in the GaAs substrate by initiating the etch using a low RF bias power;
increasing a power level between about 1.5 kW to 4 kW of the inductively coupled plasma processing system to more fully dissociate the high Cl 2 flows;
removing the GaAs substrate from the plasma processing system; and
stripping said mask layer from the GaAs substrate.
8. The method of claim 7 wherein said processing system having an inductively coupled plasma confinement ring.
9. The method of claim 7 further comprising the step of decreasing a residence time of an etch gas used during an etching process to prevent the formation of pillars.
10. The method of claim 7 comprising the step of ramping the RF power between different levels between process steps to eliminate pillar formation during the etch process.
11. The method of claim 7 wherein the etch process further comprises an ion assisted etch process.
12. An improved method for forming via holes in a GaAs substrate comprising the steps of:
forming a mask layer on the GaAs substrate;
placing said GaAs substrate in an inductively coupled plasma processing system;
decreasing a residence time of an etch gas used during an etching process to prevent the formation of pillars;
etching via holes in the GaAs substrate by increasing a power level of the inductively coupled plasma processing system to more fully dissociate the etch gas;
removing the GaAs substrate from the plasma processing system; and stripping said mask layer from said GaAs substrate.
13. The method of claim 12 wherein said processing system having an inductively coupled plasma confinement ring.
14. The method of claim 12 further comprising the step of introducing high Cl 2 flows into the processing system.
15. The method of claim 12 further comprising the step of initiating the etch using a low RF bias power.
16. The method of claim 12 comprising the step of ramping the RF power between different levels between process steps to eliminate pillar formation during the etch process.
17. The method of claim 12 wherein the etch process further comprises an ion assisted etch process.
18. An improved method for forming via holes in a GaAs substrate comprising the steps of:
forming a mask layer on the GaAs substrate;
placing said GaAs substrate in an inductively coupled plasma processing system;
initiating the etch using a low RF bias power;
etching via holes in the GaAs substrate by ramping the RF power between different levels between process steps to eliminate pillar formation during the etch process;
removing the GaAs substrate from the plasma processing system; and
stripping said mask layer from said GaAs substrate.
19. The method of claim 18 wherein said processing system having an inductively coupled plasma confinement ring.
20. The method of claim 18 further comprising the step of introducing high Cl 2 flows into the processing system.
21. The method of claim 20 further comprising the step of increasing a power level of the inductively coupled plasma processing system to more fully dissociate the high Cl 2 flows.
22. The method of claim 18 further comprising the step of decreasing a residence time of an etch gas used during an etching process to prevent the formation of pillars.
23. The method of claim 18 wherein the etch process further comprises an ion assisted etch process.