Multiple Patterning (SAMP) Spacers
High throughput ALD at low temperature with hydrogen peroxide vapor.
Key Challenges for SAMP Spacers
Self-Aligned Multiple Patterning technology has been widely implemented in advanced semiconductor manufacturing processes due to the minimal accessibility of EUV technology. As devices shrink, it is challenging to form a conformal spacer on small 3D & HAR features. Good uniformity and excellent conformality at >20:1 AR are critical for next generation SAMP process.
The spacer is typically deposited on a mandrel. In order to protect temperature-sensitive mandrels (e.g., a-C, Photoresist etc.), the spacer must be formed at low temperature (<150C). Conventional oxidants such as water typically require high temperature for ALD.
Controllability of Etch Rate
SAMP spacer must have a high etch contrast to underlying mandrels (Etchant: CF4, DHF etc.). Therefore, the spacer formation process needs a large window with the same material to easily differentiate etch resistance of the spacer. In addition, etch rates must be uniform on a variety of 3D surfaces (top, bottom, vertical sides, horizontal sides).
Solving SAMP Spacer Challenges
Low Sub-Surface Damage
Conventional reactive oxidants such as water and ozone plasma tend to cause damage to underlying layers. Compared to those oxidants, Hydrogen peroxide vapor has minimal oxidation rate with typical underlying materials (a-C, Photoresist, Si, SiGe, SiO2, SiN, etc).
Low Thermal Budget
Reactive hydrogen peroxide allows lower process temperature and lower overall thermal budget.
Fast Oxide Growth Rate
Hydrogen peroxide reacts with precursors faster than existing oxidants enabling high throughput ALD.
ALD SiO2 with 3DMAS and H2O2
ALD Growth Rate (3DMAS+H2O2, 3DMAS+H2O)
Water vapor could not form SiL2 at the temperature range of 300-500C
ALD SiO2 was successfully deposited with H2O2 vapor at the same temperature.
Low Sub-Surface Damage
g/h/i-line photoresist was exposed to H2O2 vapor or N2 at various temperatures
No significant difference in thickness decrease between H2O2 and N2
Removal rate increases as temperature raised – Material shrunk by heat
Peroxidizer® Competitive Advantage for SAMP Spacer
The Internet of Things requires low power and high performance semiconductor devices, which will only be enabled through new materials and 3D architectures. These new devices must be processed at lower temperature and more care must be taken to avoid damaging complicated physical structures during cleaning processes. As processes scale, oxidants must also be able to support to high volume ALD.
The Peroxidizer is the first tool to enable stable and particle-free delivery of high concentration hydrogen peroxide gas, enabling lower process temperatures, greater use of new materials and high process throughput.
Hydrogen Peroxide gas eliminates problems associated with other oxidants used in semiconductor fabrication processes. Ozone and oxygen plasma are too aggressive, penetrating below the interface layer and damaging both surface structures and bottom electrodes. Both ozone and water lead to dense interface layers.
In addition, plasma cannot deeply penetrate high aspect structures, resulting in non-uniform coatings and non-uniform etch rates.
Water is less reactive than hydrogen peroxide gas and requires higher process temperatures. These properties make water a poor choice with new materials, new precursors, and lower thermal budgets.
Hydrogen peroxide gas is more reactive than water at low temperatures. High reactivity enables process engineers to use precursors that normally would not react with water or ozone. This reactivity also results in active removal of carbon.
Hydrogen peroxide gas achieves higher density nucleation than other oxidants. Hydrogen peroxide has less steric hindrance than water or ozone because it decomposes into hydroxyls on surfaces. The resulting dense layer of hydroxyls creates an ideal surface for ALD.
Read more about the Peroxidizer.
RASIRC products generate and deliver water vapor, hydrogen peroxide and hydrazine gas in controlled, repeatable concentrations to critical processes.
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