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HfSiOx Deposition Using H2O Atomic Layer Deposition Disclosure Number: IPCOM000198320D
Publication Date: 2010-Aug-04
Document File: 8 page(s) / 70K

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Disclosed herein are non-limiting embodiments of methods, apparatus, and compounds which may be used in the manufacture of semiconductor, photovoltaic, LCD-TFT, or flat panel type devices.


One of the challenges the semiconductor industry faces is developing new gate dielectric materials for DRAM and capacitors.  For decades, silicon dioxide (SiO2) has been a reliable dielectric, but as transistor size continues to shrink and as technology moves from “Full Si” transistor to “Metal Gate/High-k” transistors, the reliability and capability of the SiO2-based gate dielectric is reaching its physical limits.  One solution is to use other materials, such as hafnium-based metal oxides and namely hafnium silicates, for gate dielectrics.  It is in this context that these high-k materials (so-called because of their high dielectric constant) can be made much thicker than SiO2 while achieving the same gate capacitance.

One method of forming these structures is ALD (Atomic Layer Deposition), which has been identified as an important thin film growth technique for microelectronics manufacturing.  ALD relies on sequential and saturating surface reactions of alternatively applied precursors, separated by inert gas purging.  The surface-controlled nature of ALD enables the growth of thin films of high conformality and uniformity with an accurate thickness control.

Currently, HfO2 can be easily deposited using various reducing agents such as ozone, oxygen, or moisture by ALD.  However, silicon containing film deposition by ALD with moisture has been proven to be challenging.

Current known processes do not allow deposition of SiO2 films using aminosilane and moisture by ALD. 

HfO2  film deposition using moisture has been widely disclosed.  For instance, recently Niinisto et al. (J. of the Electrochemical Society, Vol. 153, No. 3, F39-F) used cyclopentadienyl precursors in combination with moisture to deposit HfO2 on silicon substrate. 

HfSiOx deposition using O3 is also known, for example by Sensaki et al. (ECS proceeding volume 2004-01 p264) using TEMAHf and TEMASi.  The films were deposited up to 400C.

However with these and other methods, the inevitable oxidation on the substrate during the ozone pulse in the ALD process dramatically affects the electrical properties of the resulting film.  There were many works attempting to suppress the oxidation on silicon substrates, one of the major step is to use moisture instead of ozone.  Moisture is well known to be less oxidant than ozone, but these approaches have also faced drawbacks.

SiO2 film deposition by ALD has proven to be difficult.  SiCl4 is commonly used but after few cycles, there is a need for a catalyst to maintain the growth rate (Klaus et al., J. of the Electrochemical Society, 147(7) 2658-2664 (2000)). 

Uchida et al. (Jpn. J. Appl. Phys. 35 (1996) pp. 1460-1463) have shown that TICS (tetra isocyanato silane) doe...