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Hard masks used in lithography processes play a vital role in pattern transfer to the desired substrate. Hard mask materials can be categorized into organic and inorganic types. Examples of organic type hard masks include amorphous carbon, organo siloxane based materials with reflection control properties. These organic hard masks are deposited either by CVD process or spin-on processes. SiN, SiON and TiN are some examples of inorganic type hard masks and typically these hard masks are deposited through CVD process. In either type, key requirement is etch resistance to either oxygen rich plasma or halogen rich plasma depending on the substrate to be etched away. However, in the advanced lithography processes, in addition to good etch resistance, they also need to possess good wet removability, fill capability in high aspect ratio contacts and trenches. In this paper, we discuss the advances made in the spin-on organic and inorganic hard masks. The spin-on option provides high throughput and several alternate material options compared to CVD option. Spin-on carbon (SOC) is a high carbon containing polymer solution and as a coating material, the polymers need to be soluble in organic solvent and insoluble after curing for coating upper layer materials. Recent progress made in good filling, low outgas, high thermal stability and planarization properties required for double and quadruple patterning is presented. Similarly, novel spin-on type inorganic formulations providing Ti, W, and Zr oxide hard masks with high etch selectivity, wet removal capability and good shelf-life stability are described. These novel AZ ® Spin-on MHM formulations can be used in several new applications and can potentially replace any metal, metal oxide, metal nitride or silicon-containing hard mask films currently deposited using CVD process in the semiconductor manufacturing process.

Metal oxide or metal nitride films are used as hard mask materials in the semiconductor lithography processes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput.The present paper describes formation and functional properties of novel metal oxide hard masks by simple solution spin coating process. These stable metal oxide formulations containing significant amount of Ti, W, Hf, Zr and Al possess good etch selectivity and therefore good pattern transfer capability. The metal oxide films can be removed by commonly used wet chemicals in the fab environment such as TMAH developer, solvents or other oxidizing agents.The hard mask material absorbs DUV wavelengths and hence can be used as a spin-on inorganic or hybrid antireflective coating to control substrate reflectivity. Some metal hard masks are also developed for via or trench filling applications for electronic devices as high K materials. The research demonstrated that these metal oxide hard masks are compatible with litho track and etch processing without concern of metal contamination. They can, therefore be integrated as replacements of CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV processes. This paper discusses coating, optical, filling, etch and wet removal properties the spin-on metal oxide formulations. In addition, a new potential application in self-aligned quadruple patterning cut process for advanced technology nodes is also described.

Hard masks play an important role in pattern transfer to the desired substrate in the semiconductor lithography processes. Organic and inorganic type hard masks are used. While most organic hard masks such as carbon and siloxane type are solution spin coated, inorganic type hard masks such as SiON and SiN are either chemical vapor deposited (CVD) or atomic layer deposited (ALD). Future generation of lithography processes require hard masks with higher resistance to fluorinated plasma and materials that can be easily wet stripped after pattern transfer process to prevent dry etch damage to the substrate underneath.The present paper describes formation and functional properties of novel metal oxide hard masks by simple solution spin coating process. These novel metal oxide hard masks offer good etch selectivity and can easily be partially or fully wet strippable using commonly used chemicals in the FABs. The spin coatable composition has good long-term shelf life and pot life stability based on solution LPC analysis and wafer defect studies. The hard mask material absorbs DUV wavelengths and can be used as a spin-on inorganic or hybrid antireflective coating to control substrate reflectivity under DUV exposure of photoresist. At the same time they are transparent at 500-700nm for alignment mark identification and can be spin coatable up to 450nm thickness with good film quality. Some of these metal-containing materials can be used as an underlayer in EUV lithography to significantly enhance sensitivity of the photoresist. Specific metal hard masks are also developed for via or trench filling applications in IRT processes. The materials have shown good coating and lithography performance with a film thicknesses as low as 10 nm under ArF dry or immersion conditions.

Hardmasks are indispensable materials during pattern transfer to the desired substrates in the semiconductor manufacturing process. Primarily there are two types of hardmask materials -organic and inorganic -and they can be coated onto substrates or underlying materials either by a simple spin-on process or by more expensive methods such as chemical vapor deposition (CVD), atomic layer deposition (ALD) and sputtering process. Most inorganic hardmasks such as SiO2, SiON, SiN and TiN are deposited using the CVD process.Future nodes require hardmasks with high etch resistance as the designs move from horizontal to vertical (3D). We have reported novel spin-on metallic hardmasks (MHM) with comparable or higher etch resistance than SiO2. 1-2 In addition to high etch resistance, they are easy to remove using wet etch chemicals. The spin-on process offers high throughput and commonly used spin tracks can be utilized; thereby reducing overall process costs when compared with CVD.Via-fill performance is also an important attribute of hardmask materials for these future nodes. Organic spin-on materials, both siloxane-and carbon-based, are used in filling applications of deep via or deep trench fill, such as those found in LELE double-patterning schemes. Inorganic materials deposited by either chemical vapor deposition (CVD) or atomic layer deposition (ALD) have higher resistance to oxygenated plasma than organic materials, but are hindered by their poor filling performance. Therefore, novel tungsten (W) containing MHM materials having both good filling performance and higher resistance to oxygenated plasma than organic materials would be of value in some filling applications. The present paper describes specific metal oxides useful for filling applications. In addition to basic filling performance and etch resistance, other properties such as optical properties, outgas and shelf life via forced aging etc. will be discussed.