Plasma etching chamber parts made with EDM

Abstract

A method is disclosed for manufacturing chamber parts for plasma etching chambers involving electronic discharge machining (EDM) methods that allows silicon and other ceramic materials to be formed and drilled. Key factors disclosed relate to the clamping of such materials for the EDM machining to avoid the electrical current inhibiting influence of oxide coatings that these materials can form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic image of one style of plasma etch chamber electrode.

FIG. 2 pictures the plasma chamber part being electrical discharge machined with clamping that is making good electrical contact with the ceramic material.

BEST MODE FOR CARRYING OUT THE INVENTION

The PLASMA ETCHING CHAMBER PARTS MADE WITH EDM is associated with many steps such as grinding, polishing, acid dipping, cleaning, and occasionally bonding, but these steps are well known and familiar to any one involved with the art of dealing with hard brittle materials. This disclosure focuses on the clamping of the parts to the machine that performs the EDM function because it is absent in previous art. The PLASMA ETCHING CHAMBER PARTS MADE WITH EDM uses the characteristic of hardness in the clamping material to provide good electrical contact between the ceramic and the EDM machine. The diagrammatic image of the plasma etch camber electrode is a plate of hard brittle material numbered 1 in FIG. 1. The image has holes drawn in it. The number and position of these holes are different for different plasma chambers. These holes are numbered 2 in FIG. 1. This disk is given as an example only; there are other chamber parts that must be machined by the present method that are not simple disks. EDM tool 5 in FIG. 2 brings the electrical discharge to the ceramic part that is being machined numbered 7 in the drawing. The tool is usually spinning and water-cooled. The polarity of the electricity that it brings can be changed from positive to negative at the will of the machinist. The contact between the tool and the ceramic usually occurs in a bath of solution, which is agitated to remove particles from the machining process. The coolant may also flow through the tool for efficiency.

The PLASMA ETCHING CHAMBER PARTS MADE WITH EDM can machine many shapes in the ceramic materials besides round holes. The electrical lead 6 in FIG. 2 is the electrical supply voltage wire. Electrical lead 6 can be made to supply positive or negative polarity electricity. Electrical lead 9 in FIG. 2 is the return or ground electrical lead. Electrical lead 9 also may be electrically positive or negative. The clamp 8 in FIG. 2 is the clamp that holds down the ceramic piece 7, and it provides good electrical connection for the ceramic piece to the EDM machine. The hardness of this clamp 8 being less than Rockwell Hardness of 60 allows the effect of surface oxide on the ceramic to be minimized. In this way the surface oxide will not inhibit the free flow of electricity to the part. The clamp can be of softer material but the surface of the ceramic that the clamp will be seated on must be scrubbed with abrasive material to remove the oxide coating. The ceramic may have inhibiting layers that are not best typified by the name oxide. Whatever the chemical composition of the inhibiting layer, it must be removed or circumvented to allow the best results from the EDM machining. Materials that can be machined include silicon carbide, silicon, ferrites, and polycrystalline diamond. For the speed and accuracy of the EDM machining is greatly enhanced by the removal of the oxide or inhibiting layer on the ceramic. The mounting platform 10 in FIG. 2 is the surface that the ceramic rests on while it is being machined. Mounting platform 10 provides electrical contact between the ceramic and the EDM machine by way of the clamp labeled 8.

Other details of EDM machining are read in U.S. Pat. No. 5,498,848 by Kimihiro Wakabayashi and Noriyuki Nebashi, which teaches a METHOD AND APPARATUS FOR ELECTRIC DISCHARGE MACHINING, here included by reference. These details are of some interest, but with out proper clamping the EDM machining will be inhibited. The drawings provided in this disclosure are schematic only and actual equipment will have other features that are not necessary to the understanding of the present invention.

Claims

1. A method for manufacturing chamber parts for plasma etching chambers composed of materials including silicon, silicon carbide, titanium nitride, ceramics, and other hard brittle materials that have sufficiently low resistivity for using electrical discharge machining (EDM) with good electrical contact between the machine and the material being machined.

2. An EDM as claimed in claim one where the metal clamp tooling has Rockwell Hardness of 60 or less.

3. An EDM as claimed in claim one where the metal clamp tooling is of metals of unspecified hardness that clamps on a surface of the ceramic has been abraded to remove surface inhibitors to the electrical contact.

4. An EDM as claimed in claim one where the metal clamp tooling is of metals of unspecified hardness that clamps on a surface of the ceramic that has been abraded to remove surface inhibitors to the electrical contact that are oxides.

5. Process is claimed for manufacturing plasma etching chamber parts that have low resistivities using electrical discharge machining where the clamping of the part to the machine allows good contact between the part being machined and the machine by maintaining the hardness of the clamp to below a Rockwell Hardness of 60.

6. Process is claimed for manufacturing plasma etching chamber parts that have low resistivities using electrical discharge machining where the clamping of the part to the machine allows good contact between the part being machined and the machine by cleaning the surface of the ceramic thoroughly that will make contact with the electrical discharge machine.