Methods relating to wafer integrated plasma probe assembly arrays

• US 6,781,393 B2
• Filed: 10/06/2003
• Issued: 08/24/2004
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Benjamin, Neil
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US10/680,791
• Publication Number:
  US 20040066206A1
• Time in Patent Office: 323 Days
• Field of Search: 324/754-762, 324/73.1, 324/158.1, 439/482, 439/824, 295/93
• US Class Current: 324/754.24
• CPC Class Codes: H01L 22/34 Circuits for electrically characterising or monitoring manufacturing processes, e. g. whole test die, wafers filled with test structures, on-board-devices incorporated on each die, process control monitors or pad structures thereof, devices in scribe line switching, multiplexing, gating devices G01R19/25; process control with lithography, e.g. dose control, G03F7/20; structures for alignment control by optical means G03F7/70633
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A wafer integrated plasma diagnostic method for a semiconductor wafer processing system provides a multiplicity of plasma probe assemblies arranged on a wafer in a planar array fashion such that one plasma probe assembly is located in the center and eight more plasma probe assemblies are located at intermediate positions such that they lie along the radius from the center to the corners; such corners forming four corners of a square box near the edge of the wafer. Method operations provide at each location and in each of the plasma probe assemblies, six possible probe elements having a relative geometrical area such that the assemblies may make simultaneous measurements of both spatial resolution and real time measurement of different plasma characteristics at the wafer surface, such as: D.C. potential, A.C. potential, shading induced potentials, ion fluxes, ion energy distribution, and the electron part of the I-V Langmuir probe characteristic.

Claims

1. A method for monitoring a plasma, the method comprising the operations of:

providing a plurality of plasma probe assemblies, each of the plurality of plasma probe assemblies comprising a substrate and a plurality of Langmuir probes, each of the Langmuir probes comprising a larger probe, four medium sized probes, and a smaller probe, each of the larger sized probes having a geometrical area equal to the geometric area of the four medium sized probes, and the smaller probe having an area which is one-hundredth the area of all the probes combined;

inserting the plurality of plasma probe assemblies into a plasma chamber;

coupling the plurality of plasma probe assemblies to an analyzer; and

monitoring the plasma formed in said chamber with the analyzer.

2. A method as recited in claim 1, wherein the providing operation provides the substrate of the plurality of plasma probe assemblies made from low impedance N type silicon.

3. A method as recited in claim 1, wherein the providing operation provides the four medium sized probes as patterned probes.

4. A method as recited in claim 1, wherein the providing operation provides all of the Langmuir probes smaller than an exposed substrate contact.

5. A method as recited in claim 1, wherein the providing operation provides the smaller probe with a geometrical area of about 0.25 square mm.

6. A method as recited in claim 1, wherein the providing operation provides the exposed substrate contact as a low impedance ohmic contact.

7. A method as recited in claim 3, wherein patterning on the four medium sized probes constitutes four different aspect ratios.

8. A method as recited in claim 1, wherein the providing operation provides all the Langmuir probes much smaller than an exposed substrate contact.

9. A method for making a plasma probe assembly for monitoring a plasma, the method comprising the operations of:

providing a substrate; and

mounting a plurality of Langmuir probes on the substrate, the mounting operation comprising;

defining the Langmuir probes as comprising a larger probe, four medium sized probes, and a smaller probe;

configuring the larger sized probe to have a geometrical area equal to the geometric area of the four medium sized probes; and

configuring the smaller probe to have an area which is one-hundredth the area of all the probes combined.

10. A method as recited in claim 9, wherein the providing operation provides the substrate from low impedance N type silicon.

11. A method as recited in claim 9, wherein the defining operation provides the four medium sized probes as patterned probes.

12. A method as recited in claim 9, wherein the mounting operation further comprises mounting an exposed contact on the substrate, wherein all of the Langmuir probes are smaller than the exposed substrate contact.

13. A method as recited in claim 9, wherein the smaller probe configuring operation configures the smaller probe with a geometrical area of about 0.25 square mm.

14. A method as recited in claim 12, wherein the mounting operation provides the exposed substrate contact as a low impedance ohmic contact.

15. A method as recited in claim 11, wherein patterning of the four medium sized probes constitutes four different aspect ratios.

16. A method for making a plasma probe for monitoring a plasma, the method comprising the operations of:

providing a plurality of plasma probe assemblies, each of the plurality of plasma probe assemblies comprising a substrate and a plurality of Langmuir probes, each of the Langmuir probes comprising a larger probe, four medium sized probes, and a smaller probe, each of the larger sized probes having a geometrical area equal to the geometric area of the four medium sized probes, and the smaller probe having an area which is one-hundredth the area of all the probes combined;

providing a first of the plasma probe assemblies located at a center of a wafer;

defining a square box disposed near an edge of the wafer, the square box defining four corners; and

arranging a first four of the plasma probe assemblies in a pattern, one of the plasma probe assemblies being disposed along a respective radius from the center to a respective one of the corners of the square box.

17. A method as recited in claim 16, the method further comprising the operation of:

arranging a second four of the plasma probe assemblies in the pattern, one of the second four plasma probe assemblies being disposed along each respective radius between the first plasma probe assembly and one of the first four plasma probe assemblies.

18. A method as recited in claim 17, the method comprising the further operation of connecting the plurality of plasma probe assemblies to an analyser to enable simultaneous measuring of a set of six different real time plasma quantities.

19. A method as recited in claim 18, wherein the six different real time plasma quantities include D.C. potential, A.C. potential, shading induced potentials, ion fluxes, ion energy distribution, and the electron part of the I-V Langmuir probe characteristic.

20. A method as recited in claim 17, wherein the arranging of the second four plasma probe assemblies rotates the second four plasma probe assemblies with respect to the first plasma probe assembly and to the first four plasma probe assemblies that are respectively provided and arranged at the center and at the corners of the wafer.