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Plasma Al2O3

Surface Roughness and Uniformity Characterization 

 

500 cycles of Plasma AlOx was deposited on a clean Si wafer. Surface roughness and uniformity was measured using AFM and Woollam, respectively by Kye Okabe (okabeATstanfordDOTedu). Data was obtained during February, 2014.

 
Surface Roughness 

< 3 [nm] ...Temperature = 200 [℃] 
< 2 [nm] ...Temperature = 250 [℃]
*Temperature indicates the temperature of the Reactor Heater 1&2, Chuck Heater, and Cone Heater. 
 
Uniformity

Temperature = 200 [℃]
Mean: 520.08 [Å]
Min: 501.75 [Å]
Max: 532.42 [Å]
Std Dev: 8.3817
Uniformity: 1.6116 [%] 
 
Temperature = 250 [℃]
Mean: 467.70 [Å]
Min: 456.52 [Å]
Max: 475.97 [Å]
Std Dev: 5.3857
Uniformity: 1.1515 [%] 
 
*Note that roughly 14 [Å] of the thickness reported above is contributed by the native SiOx and is not AlOx.

 

AFM of AlOx (Fiji1/200℃/500cycles/100cycle seasoning)

1.0x1.0 [μm] AFM Image of Plasma AlOx, 200 [℃], 500 [cycles] w/100 [cycles] seasoning, Fiji1 

 

#27 AlOx AFM 250C Fiji2 lots seasoning 500 cycles

1.0x1.0 [μm] AFM Image of Plasma AlOx, 250 [℃], 500 [cycles] w/seasoning, Fiji 2

 

#33, Plasma AlOx Profile Woollam

Woollam Thickness Profile of Plasma AlOx, 200 [℃], 500 [cycles] w/100 [cycles] seasoning, Fiji1

 

#27 AlOx Woollam Profile 250C Fiji2 lots seasoning 500 cycles 

Woollam Thickness Profile of Plasma AlOx, 250 [℃], 500 [cycles] w/ seasoning, Fiji2

 

#33, Plasma AlOx MSE Woollam

Woollam Mean Squared Error (MSE) of Plasma AlOx, 200 [℃], 500 [cycles] w/100 [cycles] seasoning, Fiji1

 

#27 AlOx Woollam MSE 250C Fiji2 lots seasoning 500 cycles

Woollam Mean Squared Error (MSE) of Plasma AlOx, 250 [℃], 500 [cycles] w/ seasoning, Fiji2

 

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Stoichiometry and Contamination Characterization

 

Plasma AlOx was deposited on 3 clean Si wafers as the following;

A. Plasma AlOx (500 cycles (roughly 467Å thick), 250℃, Fiji1, w/100 cycle seasoning, air-stored)

B. Plasma AlOx (500 cycles (roughly 467Å thick), 250℃, Fiji1, w/100 cycle seasoning, N2 desiccated)

C. Plasma AlOx (500 cycles (roughly 520Å thick), 200℃, Fiji1, w/100 cycle seasoning, air-stored)

Sample B  was immediately stored in a N2 desiccator after deposition. The others were stored under regular air conditions. XPS PHI measurements were performed roughly a week later for sample A & B and two weeks later for sample C to characterize stoichiometry and contamination as a function of sputter etch time (i.e. sample thickness). Sample B was etched until a significant amount of Si was detected. Sample A was assumed to have the same bulk composition as sample B, and only the surface was analyzed to study the difference in storage conditions. Al, O, C, N, Ti, Hf, Si were included in the analysis. (C, N, Ti, Hf are elements that are frequently introduced into the chamber due to commonly used precursors.)


XPS PHI  measurements performed by Yu-Chung Lien (yuchunglATstanfordDOTedu). Sample preparation by Kye Okabe (okabeATstanfordDOTedu). XPS measurements performed on March 11th, 2014 (Sample A & B) and March 18th, 2014 (Sample C).

 AlOx XPS N2 desiccated sample 250℃ 

 Sample B: Plasma AlOx N2 desiccated (250℃, Fiji1, 500 cycles, 100 cycle seasoning, roughly 467Å thick); Sputter Etch Parameters: 1 kV, 0.5μA, 2x2 μm


AlOx XPS air fiji1 sample 200℃

 Sample C: Plasma AlOx air-stored (200℃, Fiji1, 500 cycles, 100 cycle seasoning, roughly 520Å thick); Sputter Etch Parameters: 1 kV, 0.5μA, 2x2 μm

*Note the reason for the apparent quicker etch rate compared to the 250℃ sample is unknown. 

 
Plasma AlOx air stored XPS

 Sample A: Plasma AlOx air-stored (250℃, Fiji1, 500 cycles, 100 cycle seasoning, roughly 467Å thick); Sputter Etch Parameters: 1 kV, 0.5μA, 2x2 μm


AlOx n2 and air stored Binding energy of carbon comparison
Surface Carbon Spectra Comparison of N2 desiccated sample and air-stored sample

 

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The data below was collected from Fiji2 (Fiji-R)

Thermal Al2ODeposition rate of 1.08A/cycle for standard recipe at 200C

fiji-r thermal alumina deposition rate    fiji-r thermal alumina temperature dependence
Breakdown voltage was measured at .45V/nm for a 20nm film at 200C.
 
Plasma Al2ODeposition rate of 1.08A/cycle for standard recipe at 200C

 

fiji-r plasma alumina deposition rate    fiji-r plasma alumina temperature dependence

Breakdown voltage was measured at .65V/nm for a 20nm film at 200C.

Thanks to Tim Holme and Cheng-Chieh Chao and the QuantumScape team for help with the breakdown measurements.

 

Thank you to Yongliang Yang for the following etch rate data:

Approximate etch rates of Fiji Plasma Al2O3 films:

1. BOE, etch rate is about 60nm/min
2. Pad etch, etch rate is about 30nm/min
3. Al11, ~43C, very slow, about 3-4nm/min

 

 

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