Gas distribution system for ceramic showerhead of plasma etch reactor

• US 9,245,717 B2
• Filed: 05/31/2011
• Issued: 01/26/2016
• Est. Priority Date: 05/31/2011
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Kang, Michael, Paterson, Alex
• Primary Examiner(s): Hassanzadeh, Parviz
• Assistant Examiner(s): Antolin, Stanislav
• Application Number:
  US13/118,933
• Publication Number:
  US 20120305190A1
• Time in Patent Office: 1,701 Days
• Field of Search: 118/715, 118/723.I, 118/726, 156/345.1, 156/345.33, 156/345.34
• US Class Current: 1/1
• CPC Class Codes: B01F 35/7182 with means for feeding the material with a fractal or tree-type distribution in a surface
• CPC Class Codes: C23C 16/45561 Gas plumbing upstream of the reaction chamber
• CPC Class Codes: C23C 16/45563 Gas nozzles
• CPC Class Codes: C23C 16/4558 Perforated rings
• CPC Class Codes: H01J 2237/006 Details of gas supplies, e.g. in an ion source, to a beam line, to a specimen or to a workpiece, H01J37/3244 takes precedence; environmental cells for electron microscopes H01J2237/2003; microscopes with environmental specimen chamber H01J2237/2608
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3211 Antennas, e.g. particular shapes of coils
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32642 Focus rings
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: Y10T 137/0402 Cleaning, repairing, or assembling
• CPC Class Codes: Y10T 137/85938 Non-valved flow dividers

Abstract

A gas delivery system for a ceramic showerhead includes gas connection blocks and a gas ring, the gas connection blocks mounted on the gas ring such that gas outlets in the blocks deliver process gas to gas inlets in an outer periphery of the showerhead. The gas ring includes a bottom ring with channels therein and a welded cover plate enclosing the channels. The gas ring can include a first channel extending ½ the length of the gas ring, two second channels connected at midpoints thereof to downstream ends of the first channel, and four third channels connected at midpoints thereof to downstream ends of the second channels. the cover plate can include a first section enclosing the first channel, two second sections connected at midpoints thereof to ends of the first section, and third sections connected at midpoints thereof to ends of the second sections. The channels are arranged such that the process gas travels equal distances for a single gas inlet in the gas ring to eight outlets in the cover ring allowing equal gas flow.

Claims

1. A gas delivery system useful for supplying process gas to a ceramic showerhead for an inductively coupled plasma processing apparatus wherein semiconductor substrates supported on a substrate support are subjected to plasma etching, the ceramic showerhead including radially extending gas inlets extending inwardly from an outer periphery thereof, the gas delivery system comprising:

gas connection blocks adapted to attach to the ceramic showerhead such that a gas outlet of each of the blocks is in fluid communication with a respective one of the gas inlets in the ceramic showerhead wherein an O-ring groove configured to receive an O-ring surrounds the gas outlet of each of the blocks so as to provide a seal around the gas outlet of each gas connection block;

a gas ring having equal length channels of uniform cross section therein and gas outlets in fluid communication with downstream ends of the channels, each of the gas outlets being located on a mounting surface engaging a respective one of the gas connection blocks, each of the gas outlets in fluid communication with a respective gas inlet in a respective one of the gas connection blocks;

wherein the gas ring includes eight gas outlets and the channels include a first channel extending about one-half the length of the gas ring, two second channels connected at midpoints thereof to downstream ends of the first channel, and four third channels connected at midpoints thereof to downstream ends of the second channels;

wherein the gas ring includes a bottom ring with the channels therein and an upper cover plate enclosing the channels, the cover plate having the gas outlets on an upper surface thereof and the gas connection blocks mounted on the gas ring with each of the gas outlets in fluid communication with the respective gas inlet of the respective gas connection block.

2. The gas delivery system of claim 1, wherein the gas ring includes a single gas inlet connected to a midpoint of the first channel.

3. The gas delivery system of claim 2, wherein the gas outlets are located on a radius of about 10 to 11 inches from a center of the gas ring and each of the gas connection blocks includes two mounting holes adapted to receive fasteners which attach the gas connection blocks to the gas ring, the mounting holes located about 1 inch apart.

4. The gas delivery system of claim 1, wherein the cover plate and bottom ring are made of stainless steel or polymer material.

5. The gas delivery system of claim 1, wherein the gas ring includes a gas inlet in an outer periphery thereof and the gas ring includes two free ends at a position 180°

from the gas inlet.

6. The gas delivery system of claim 5, wherein the free ends are connected by an extension limiter which limits spreading of the free ends of the ring during mounting of the gas ring on the showerhead.

7. The gas delivery system of claim 1, wherein the gas ring is rectangular in cross section, the gas channels are rectangular in cross section, the cover plate has a thickness of about 0.03 inch and is located in a recess in an upper surface of the bottom ring, the cover plate includes rounded ends, the rounded ends having a diameter of about 0.32 inch and through holes in the centers of the rounded ends, the through holes having a diameter of about 0.19 inch.

8. The gas delivery system of claim 7, wherein the channels in the bottom ring have a width of about 0.1 inch and height of about 0.32 inch, the upper surface of the bottom ring including a recess which contains the cover, the recess having a width of about 0.12 inch along the channels.

9. The gas delivery system of claim 1, wherein the gas outlet of the gas connection block is located in a vertical mounting surface which engages an outer periphery of the showerhead, first and second bores extending through the vertical mounting surface on opposite sides of the gas outlet and first and second shoulder screws movably mounted in the bores, the shoulder screws having ends which engage fasteners mounted in mounting holes in the showerhead.

10. The gas delivery system of claim 9, wherein the gas inlet of the gas connection block is located in a horizontal mounting surface which engages an upper surface of the gas ring, first and second mounting holes extending through the horizontal mounting surface and screws in the mounting holes attaching the gas connection block to the gas ring.

11. The gas delivery system of claim 10, wherein the horizontal mounting surface includes an O-ring groove and an O-ring therein providing a seal around the gas inlet in the gas connection block.

12. The gas delivery system of claim 11, wherein the vertical mounting surface includes an O-ring groove and an O-ring therein providing a seal around the gas outlet in the gas connection block.

13. A method of mounting the gas delivery system of claim 1 on the showerhead, comprising positioning the gas ring around the showerhead such that the gas outlets of the gas connection blocks are aligned with gas inlets in the outer periphery of the showerhead, and fastening the gas ring to the showerhead.

14. The method of claim 13, wherein the positioning comprises expanding free ends of the gas ring and sliding the gas ring vertically over the showerhead, and the fastening comprises contracting the free ends and tightening an extension limiter attached between the free ends such that the gas ring is held in position around the showerhead.

15. The method of claim 14, wherein the fastening further comprises placing vertical fasteners with horizontal holes therein in mounting holes in an upper surface of the showerhead, sliding horizontal shoulder screws mounted in bores of the gas connection blocks into horizontal mounting holes in an outer periphery of the showerhead such that the shoulder screws enter the horizontal holes in the vertical fasteners.

16. The gas delivery system of claim 1 wherein the cover plate includes a first section enclosing the first channel, two second sections connected at midpoints thereof to ends of the first section enclosing the two second channels, and third sections connected at midpoints thereof to ends of the second sections enclosing the four third channels.

17. The gas delivery system of claim 1, wherein the cover plate is slightly wider than the respective first channel, two second channels, and four third channels of the bottom ring wherein the cover plate fits within a recess at the top of each of the respective first channel, two second channels, and four third channels.