Specific Process Knowledge/Thin film deposition/ALD2 (PEALD)/TiN deposition using ALD2

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This page is written by DTU Nanolab internal

This page is written by Evgeniy Shkondin @DTU Nanolab if nothing else is stated.
All images and photos on this page belongs to DTU Nanolab.
The fabrication and characterization described below were conducted in 2017 - 2021 by Evgeniy Shkondin, DTU Nanolab.

The initial results tested in 2017 can be found here.

Deposition of TiN is a standard, well-explored ALD process. In any book where ALD is explained or scientific reviews on a subject, the TiN process is mentioned as a standard example of nitride deposition with the corresponding reaction mechanism. In any facility with an ALD tool, you will also find a TiN process, since the film is popular in many applications because of its ease of deposition, excellent uniformity, strict thickness control, and reliability. At DTU Nanolab, you can use ALD-2 for the deposition of TiN with thermal or plasma methods.

TiN ALD deposition using TiCl4 and NH₃

Thermal TiN can be deposited in the range between 450 °C to 500 °C.

TiN recipes

TiN thermal Nanolab Standard

Maximum deposition thickness: 100 nm

Temperature: 450 °C - 500 °C

	TiCl4*	NH3
Nitrogen flow	80 sccm	100 sccm
Pulse time	0.1 s	4.0 s
Purge time	5.0 s	8.0 s

This is a standard recipe of thermal TiN. It is suitable for coating the flat samples and structures with an aspect ratio of around up to 1:20.

Deposition characteristics

The deposition rate for TiN depends on the temperature, see the ALD-window graph below. The uniformity, thickness, refractive index has been obtained using Ellipsometer VASE.

Deposition rate

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  Deposition rate of TiN at 350 °C. Substrate: Silicon 6" wafer with 300 nm dry SiO2.
  $Thickness(nm)=0.0130\cdot N-13$
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  Deposition rate of TiN at 400 °C. Substrate: Silicon 6" wafer with 300 nm dry SiO2.
  $Thickness(nm)=0.0173\cdot N-0.68$
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  Deposition rate of TiN at 450 °C. Substrate: Silicon 6" wafer with 300 nm dry SiO2.
  $Thickness(nm)=0.0311\cdot N-12.87$
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  Deposition rate of TiN at 500 °C. Substrate: Silicon 6" wafer with 300 nm dry SiO2.
  $Thickness(nm)=0.0245\cdot N-5.98$
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  Deposition rate of TiN in a temperature range 350 °C - 500 °C.

Uniformity

Sample	Minimum thickness (nm)	Maximum thickness (nm)	Average thickness (nm)	Standard deviation	Uniformity (%)
500°C / 1300 cycles	29.21	39.20	32.51	2.49	15.37
500°C / 2300 cycles	56.75	76.39	62.64	5.18	15.67
500°C / 3300 cycles	82.99	107.45	92.25	6.88	13.26
500°C / 4300 cycles	107.56	141.44	118.86	8.92	14.25
500°C / 5300 cycles	133.53	180.00	148.38	12.96	15.66
500°C / 6300 cycles	169.57	250.00	210.46	31.01	19.11

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  Uniformity
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  Uniformity

Sheet resistance

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  Deposition rate of Al₂O₃ at 100 °C. Substrate: Silicon 4" wafer with native oxide.
  $SheetResistance(\mathrm{\Omega }/sq)=9.796+\frac{294700}{t^2}$, where t is a thickness.
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  Deposition rate of Al₂O₃ at 100 °C. Substrate: Silicon 4" wafer with native oxide.
  $Thickness(nm)=0.0928\cdot N$
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  Deposition rate of Al₂O₃ at 100 °C. Substrate: Silicon 4" wafer with native oxide.
  $Thickness(nm)=0.0928\cdot N$

Annealing

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  TiN as deposited at 500 °C and as result of post treatment. Annealing at different temperatures from 700 °C to 900 °C.
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  Si trench template covered with TiN before and after annealing at 900 °C. Silver and gold colored chips, respectively.

SEM

Cross-section of flat samples

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  Mag 300kX

Flat samples

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HARS

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Roughness

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  Deposition rate of Al₂O₃ at 100 °C. Substrate: Silicon 4" wafer with native oxide.
  $Thickness(nm)=0.0928\cdot N$

Optical functions

500 °C

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450 °C

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Transmission function

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X-ray photoelectron spectroscopy

Effect of temperature

Stoichiometry results for TiN deposited with TiCl4 and NH3 thermal process.
Temperature °C	500	450	400	400 (LET*)	350
Ti (At. %)	45.30	44.63	44.37	44.46	44.40
N (At. %)	38.99	38.62	36.18	37.53	34.35
O (At. %)	15.71	15.27	15.97	15.27	16.76
Cl (At. %)	0	1.47	3.48	2.74	4.49

^*LET - Longer exposure time of NH₃ (5s)

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Effect of annealing

Surface

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Depth

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