Solid state source introduction of dopants and additives for a plasma doping process

• US 8,889,534 B1
• Filed: 11/08/2013
• Issued: 11/18/2014
• Est. Priority Date: 05/29/2013
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Ventzek, Peter L. G., Kobayashi, Yuuki
• Primary Examiner(s): Garber, Charles
• Assistant Examiner(s): Seven, Evren
• Application Number:
  US14/075,453
• Publication Number:
  US 20140356984A1
• Time in Patent Office: 375 Days
• Field of Search: None
• US Class Current: 438/513
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis
• CPC Class Codes: H01L 21/2236 from or into a plasma phase
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

A method of doping a non-planar surface or a surface of a substrate subject to poor view factors is provided. The processing chamber comprises a window, walls, and a bottom of the processing chamber with oxygen-containing material, the processing chamber configured to supply oxygen radicals as an additive to doping materials. One or more quartz pieces are placed inside the processing chamber, where a magnet proximate to the processing chamber is configured to create a local magnetron plasma inside the processing chamber. Process gas containing an inert gas, sublimated doping materials, and optionally oxygen gas is flowed into the processing chamber; energy is applied to the process gas, generating a doping plasma used to expose a portion of the substrate surface while controlling operating variables to achieve target uniformity of dopant concentration, sheet resistance, degree of dopant clustering, and erosion of features on the substrate.

Claims

1. A method of doping a portion of a surface of a substrate, the surface being non-planar and/or subject to one or more poor view factors, the method comprising:

constructing a microwave window, one or more walls, and a bottom of a process chamber with an oxygen-containing material, wherein the oxygen from the microwave window, the one or more walls and the bottom of the process chamber is configured to supply oxygen radicals as additives to one or more doping materials;

providing the substrate having a layer that requires doping, the substrate positioned in the process chamber;

placing one or more quartz pieces inside the process chamber;

placing one or more magnets proximate to the process chamber, the one or more magnets and the one or more quartz pieces configured to create a local magnetron plasma inside the process chamber;

flowing a process gas into the process chamber, wherein the process gas contains an inert gas and one or more sublimated doping materials, and optionally oxygen gas;

applying microwave energy to the process gas, the microwave energy having a power, the application of microwave energy generating a doping plasma;

exposing the portion of the surface of the substrate to the doping plasma to achieve a target dose of doping materials in the portion of the surface; and

controlling one or more operating variables of a doping process in order to achieve a target uniformity of dopant concentration, a target sheet resistance, target degree of dopant clustering, and target erosion of features on the substrate.

2. The method of claim 1 further comprising forming a thin oxide layer on at least one interior surface of the process chamber.

3. The method of claim 2 further comprising forming a thin phosphorus film on at least one interior surface of the process chamber.

4. The method of claim 1 wherein the substrate with the non-planar surface or surface subject to poor view factors includes silicon nanowires, features with high aspect ratios, fin-shaped field effect transistor (FINFET) structures, or vertical memory devices.

5. The method of claim 1 wherein the target uniformity of dopant concentration is less than 3% across the wafer.

6. The method of claim 1 wherein the target sheet resistance is a range from 200 to 400 ohms per square.

7. The method of claim 1 wherein the target degree of dopant clustering is expressed as a target dopant to oxygen ratio prior to an anneal process, the target dopant to oxygen ratio ranging from 0.1% or less.

8. The method of claim 1 wherein the target erosion is a range of from 1 nm corner loss or less.

9. The method of claim 1 wherein a depth of the doping materials is in a range from 2 nm to 10 nm, and wherein the target dose is selected from:

in the range of from 10¹² cm<sup>−

2</sup> to 10¹⁶ cm<sup>−

2</sup>, below a saturation limit of the substrate, or less than 5 atomic percent.

10. The method of claim 1 wherein the target dose after the anneal process is obtained using helium or argon as the inert gas and when a vacuum pump coupled to the process chamber is turned on.

11. The method of claim 1 wherein the doping plasma is delivered from a radial line slot array (RLSA) plasma source.

12. The method of claim 1 wherein a sputtering rate of energetic plasma ions of the doping plasma is controlled by varying the power of the microwave power source.

13. The method of claim 1 wherein oxygen dose is correlated to the sheet resistance of the layer of the substrate, the correlation used to control the one or more operating variables of the doping process to achieve the target sheet resistance.

14. The method claim 1 wherein the flowed process gas does not include oxygen.

15. The method of claim 1 wherein pulsed biasing of the window of the process chamber is performed to control flux of the oxygen radicals to the doping plasma, the oxygen radicals generated from the microwave window, one or more wall, and/or the bottom of the process chamber or from the one or more quartz pieces in the process chamber.

16. The method of claim 1 where concentration of oxygen in the surface of the substrate is controlled with measurements using optical emission spectroscopy or a plasma impedance monitor.

17. The method of claim 1 wherein oxygen is flowed into the process chamber prior to flowing the process gas and prior to applying the microwave energy to the process gas and wherein the oxygen is cooled into solid oxygen by a helium cooling system.

18. The method of claim 1 wherein oxygen is initially flowed into the process chamber to saturate interior surfaces of the process chamber with the oxygen prior to flowing the process gas, applying microwave energy to the process gas and exposing the portion of the surface of the substrate to the doping plasma.

19. The method of claim 1 wherein the one or more sublimated doping materials are delivered to the process chamber using heated gas lines.

20. The method of claim 1 wherein the oxygen-containing material comprises copper oxide and/or zirconium oxide.