Al, and Ti Thin Films Anushka Walia Irvington High School 1 - - PowerPoint PPT Presentation

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Al, and Ti Thin Films Anushka Walia Irvington High School 1 - - PowerPoint PPT Presentation

Feb 07, 2024 117 likes •423 views

Optical Emission Analysis of BCl 3 /Cl 2 Plasma Etch of W, Al, and Ti Thin Films Anushka Walia Irvington High School 1 Centura MET (ICP chamber) 2 Power sources Inductively coupled source power through chamber wall Platen Bias Power

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SLIDE 1

Optical Emission Analysis of BCl3/Cl2 Plasma Etch of W, Al, and Ti Thin Films

Anushka Walia Irvington High School

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SLIDE 2

Centura MET (ICP chamber)

  • 2 Power sources
  • Inductively coupled source power through chamber wall
  • Platen Bias Power
  • Independent power sources allow lower pressure inside the

chamber

  • More control of system

ICP Platen

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SLIDE 3

Mechanism

Standard etch recipe (MET_AL_ME) Metal (M) Si Cl ions MClx

1. RF power causes molecules to dissociate and form ions 2. Ions are accelerated downwards by bias power 3. Ions/Activated neutrals adsorbed

  • nto surface of substrate, where

reaction occurs 4. Product molecules are desorbed from the surface of the substrate and removed from the chamber (by bias power)

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SLIDE 4

OES Technique

  • Technique used to determine elemental composition
  • f samples
  • Utilizes unique emission spectra
  • Wavelength range: 160 – 770 nm

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SLIDE 5

Mechanism

1. Electrons stripped by RF power, ionizing gas species 2. As electrons recombine with the ions, light emitted at specific wavelengths 3. Diffraction grating splits light 4. Detectors measure light intensity at different wavelengths – emission spectrum of atom/molecule Emission spectrum used to identify species present, intensity of light is used to measure relative concentrations

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SLIDE 6

Multi-wavelength OES

  • Multi-wavelength OES can monitor multiple

wavelengths instead of only 1-2

  • Allows for investigation of secondary lines to confirm

species

  • Can choose lines to maximize signal to noise ratio
  • Endpoint detection
  • Contaminant detection

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SLIDE 7

Experimental Plan

Goal: Optical emission analysis of species present in plasma etches of various materials

  • W/Si, W/SiO2, Ti/Si, Ti/SiO2, Al/Si, Al/SiO2
  • Bare Si before and after each wafer
  • Monitor etch conditions using OES
  • Analysis of data
  • Baseline fingerprint of materials relevant to the etch
  • Identify useful wavelengths

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SLIDE 8

MET setup

  • x2 2-meter Fiber Patch Cables from Thorlabs with

range 200-1200 nm

  • Spectrophotometer
  • OceanView software

MET Chamber C Computer Cable #1 Cable #2 Spectrometer USB

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SLIDE 9

Species Wavelength AlCl3 (AlCl) 261, 265, 268 BCl3 (BCl) 272, 267 Cl2 309 SiCl4 (SiCl) 281,282,287 W 272 201 407 430 Ti 335 365 400 TiCl 419

Relevant Wavelength Data

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SLIDE 10

Cl2 on Bare Si

SiCl Band

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SLIDE 11

BCl3 on Bare Si

BCl3 Band

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SLIDE 12

Al/Si

Al / AlCl peaks

SiCl Band

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SLIDE 13

Al/Si

Endpoint

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SLIDE 14

Al/SiO2

Al peaks

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SLIDE 15

Al/SiO2

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SLIDE 16

Why SiCl with Si but not SiO2?

  • Si-O bond stronger than Si-Cl bond
  • B-O bond stronger than B-Cl bond

Al/SiO2 Al/Si

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SLIDE 17

Ti/Si

Ti peaks SiCl band

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SLIDE 18

Ti/Si

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SLIDE 19

Ti/SiO2

Ti peaks

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SLIDE 20

Ti/SiO2

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SLIDE 21

W/Si

W peaks

W peaks SiCl band

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SLIDE 22

W/Si

W etch does not have clear endpoint >4 minutes to endpoint

200 400 600 800 1000 1200 1400 1600 1800 00:00.0 00:06.6 00:13.2 00:20.0 00:26.6 00:33.2 00:39.8 00:46.4 00:53.0 00:59.6 01:06.2 01:12.8 01:19.4 01:26.0 01:32.6 01:39.2 01:45.8 01:52.4 01:59.0 02:05.6 02:12.2 02:18.8 02:25.4 02:32.0 02:38.6 02:45.2 02:51.8 02:58.4 03:05.0 03:11.6 03:18.2 03:24.8 03:31.4 03:38.0 03:44.6 03:51.2 03:57.8 04:04.4 04:11.0 04:17.6 04:24.2 04:30.8 04:37.4 04:44.0

W/Si Timeseries

506.999 (W)

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SLIDE 23

W/SiO2

W peaks

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SLIDE 24

W/SiO2

W etch does not have clear endpoint

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SLIDE 25

Bare Si

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SLIDE 26

W endpoints

WCl4 Extremely high (solid at rt) WCl5 275.6 °C WCl6 346.7°C

Boiling points of W chlorides Species with boiling points under ~300°C at standard pressure will be removed, but some W chlorides have bp above that

W Si Cl ions WClx WClx WClx

W chlorides do not get removed, act like a block => slow endpoints

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SLIDE 27

Recommendations

  • Wavelengths recommended for various etches:

Al: 264, 311, 397 Ti: 418, 431, 455, 469, 502, 521 W: 507

  • Do not run Cl based etch on W wafers
  • SF6 + O2 based etch for W
  • Check for cross contamination of S byproducts

Future testing

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SLIDE 28

Works Cited

  • “Stationary Metal Analyzers”, Ametek Materials

Analysis Division

  • P5000 Endpoint Manual

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SLIDE 29

Acknowledgements

  • Ryan Rivers
  • Jayss
  • Jesse
  • Cheryl
  • Marilyn
  • Bill Flounders

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