Liquid injection ALD of Cp- based precursors for deposition of dielectric materials

Lead Research Organisation: University of Liverpool
Department Name: School of Engineering

Abstract

The rapid growth of the silicon-based microelectronics industry since the late 1980's has fuelled a demand for greater integrated circuit functionality and improved performance at lower cost. This requires an increased circuit density, which has been achieved by a continual reduction, or scaling , in the dimensions of the field effect transistor (FET). Previously amorphous SiO2 and more recently variants of Si-O-N have been exploited in metal-oxide-semiconductor field effect transistor (MOSFET) technology, due to the stable high quality Si-SiO2 interface achievable, and excellent electrical isolation properties. Shrinking of the transistor feature size in each new 'generation' of devices, has forced the gate dielectric thickness to be reduced, to the nanometre-scale level where direct electron tunnelling effects and high leakage currents present serious obstacles to future device reliability. These 'generations' are commonly described by 'nodes' determined by the half pitch between two CMOS gate contact or first metal level. While 90nm node technologies are in industrial production, 65nm node technologies are in advanced status of industrial development and expected to enter in full production in 2007 at the latest. To move to the 45nm node and beyond, the use of materials with a higher dielectric constant (k) (cf. SiO2 derivatives) allows an equivalent capacitance to be achieved in a physically thicker insulating layer, providing reduced leakage currents. This is a multidisciplinary project with the ultimate objective of developing novel liquid injection atomic layer deposition (ALD) process technologies for the manufacture of next generation gate dielectric thin films. The principal aims of the project are therefore to develop an ALD process based on volatile cyclopentadienyl precursors for deposition of hafnium and rare-earth metal oxides, and to assess the physico-chemical and electronic properties of the resulting high-? dielectric films for semiconductor applications.

Publications

10 25 50

 
Description The main outcomes of this project were the:

• Molecular design and synthesis of volatile chemical precursors which are suitable for the liquid injection vapour deposition manufacturing methods, such as CVD and ALD. These precursors include new cyclopentadienyl (Cp) precursors for hafnium, zirconium and a range of lanthanide complexes.



• Development of liquid injection deposition processes for the manufacture of high permittivity dielectric (high-k) hafnium and lanthanide oxide thin films.



• Electrical characterisation and properties of test MOS capacitors fabricated using hafnium and rare earth oxide films. This approach was sucessfully used to elucidate key performance parameters including the electronic interface state densities, oxide charge levels, leakage currents and dielectric strength.



• Assessment of the role of hydrogen during the annealing of high k MOSC's, in the reduction of defects both and the high-k/silicon interface and in the bulk of the high k dielectric film.



Overall the project demonstrated that liquid injection provides an alternative to previous manufacturing routes, coupled with the potential for improved precursor utilisation and reduced manufacturing costs.
Exploitation Route The outcomes of the project have been exploited in TSB and EU funded industry-led projects working in the sectors of CMOS electronics, architectural glazing and power electronic devices. Several of the precursors developed were patented in conjuction with SAFC Hitech. These precursors are now sold by the company to leading IC manufacturers and research groups worldwide.
Sectors Electronics

 
Description Liquid injection has enabled the deposition of a range of dielectric materials, which has been exploited by a number of European IC manufactures for the production memory devices.
First Year Of Impact 2009
Sector Electronics,Manufacturing, including Industrial Biotechology
Impact Types Societal,Economic

 
Description SAFC Hitech 
Organisation Sigma-Aldrich
Department S a F C Hitech
Country United Kingdom 
Sector Private 
Start Year 2006
 
Title HIGH-K DIELECTRIC FILMS AND METHODS OF PRODUCING USING CERIUM-BASED DIKETONATE PRECURSORS 
Description  
IP Reference WO2009143456 
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Title HIGH-K DIELECTRIC FILMS AND METHODS OF PRODUCING USING CERIUM-BASED PRECURSORS 
Description  
IP Reference WO2009143452 
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Title HIGH-K DIELECTRIC FILMS AND METHODS OF PRODUCING USING TITANIUM-BASED DIKETONATE PRECURSORS 
Description  
IP Reference WO2009143460 
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Title HIGH-K DIELECTRIC FILMS AND METHODS OF PRODUCING USING TITANIUM-BASED PRECURSORS 
Description  
IP Reference WO2009143458 
Protection Patent granted
Year Protection Granted
Licensed No