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

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This page is written by DTU Nanolab internal

The initial results tested in 2017 can be found here.

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.

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 where you find an ALD tool, you will also find a TiN process since the film is very popular in many applications due to the 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

	TMA*	H2O
Nitrogen flow	150 sccm	200 sccm
Pulse time	0.1 s	0.1 s
Purge time	3.0 s	4.0 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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