Papers by Keyword: Cu/Low-k

Abstract: A wet cleaning formulation with tunable AlN etch rate approach was developed. The formula is compatible with Cu, Co and low-k materials, is able to remove etch residues and does not contain fluoride.

Abstract: TiN metal hardmask has been used to improve etch selectivity to low-k materials and thereby gain better profile control. For 14 nm and smaller technology nodes, it is required that the TiN hardmask is completely removed in order to improve the aspect ratio for subsequent reliable metal deposition. Thus, a chemical cleaning formulation with high TiN etch selectivity toward Cu and low-k is required.

Abstract: A novel wet cleaning formulation approach was developed with a TiN etch rate of more than 30 Å/min at room temperature and more than 100 Å/min at 50°C. The chemicals are compatible with Cu and low-k materials, and are suitable for Cu dual damascene interconnect 28 nm and smaller technology node applications. The chemicals offer a route to in situ controlled TiN pullback or even complete removal of the TiN mask during the cleaning process in single wafer tool applications. The chemicals do not contain NH₄OH or TMAH and so are very user-friendly.

Abstract: As 65nm technology in mass production and 45nm technology under development, post etch ash and cleaning faces new challenges with far more stringent requirements on surface cleanliness and materials loss. The introduction and integration of new materials, such as metal hard mask, creates additional requirements for wafer cleaning due to the occurrence of new defect modes related to metal hard mask. We have optimized a post etch ash process and developed a novel aqueous solution (AQ) based single wafer cleaning process to address these new defect modes. Physical characterization results and process integration electrical data are presented in this paper.

Abstract: To address the water mark issue from hydrophobic film drying, and the stringent particle removal requirements for the 45nm technology node and beyond, we developed a cleaner with an innovative single wafer Marangoni dryer. The single wafer Marangoni dryer design features and process characterization data are presented in this paper. The major results can be summarized as: (1) With the immersion type Marangoni dryer, as the wafer is lifted out of a DIW bath, a stable and uniform meniscus can be easily maintained, making the single-wafer Marangoni dryer ideal for drying hydrophilic, hydrophobic or hydrophobic/hydrophilic mixed patterned wafers; (2) The new Marangoni dryer leaves ~14nm [1] water film on the wafer after drying, therefore any dissolved or suspended materials contained inside the water film, and potentially left on the wafer surface after water evaporation, is less than 14nm in diameter. This feature is critical for the 45nm technology node and beyond because 23nm particle could be killer defects at these nodes [2]; (3) Because of the strong Marangoni flow effect, high aspect ratio features can be completely dried without leaving any water droplets inside the trenches; therefore copper corrosion can be prevented; (4) The Marangoni dryer uses N2 as the carrier gas, so when a wafer is lifted out of the degasified DIW bath through the N2/IPA spray zone, it is thoroughly dried in an oxygen-free environment before exposure to the ambient environment; (5) The Marangoni dryer is free of electrostatic charge and centrifugal force because of the slow (2mm/s~20mm/s) wafer linear lifting speed compared to linear speed at wafer edge during SRD.

Abstract: This paper described the development of two types of Advanced Aqueous Cleaners (AAC™) for Aluminium (Al) Post Etch Residue (PER) removal. The first approach was developed to address a need for cleaning chemistries with a smaller environmental footprint that were also able to clean at significantly lower process times and temperatures than conventional wet chemical cleans. A broad screening experiment was undertaken during which it was highlighted it was possible to clean Al lines in an acidic region though this technology was not extendable to cleaning via features. However, the study emphasised the need to use a selective alkaline reducing formulation to maintain a high cleaning efficiency for the more complex residues formed during via etch. The novel Back End Of Line (BEOL) PER cleaners presented in this paper were optimised using a statistical Design Of Experiment (DOE) to perform at lower temperatures and shorter process times and were Fluoride and organic solvent free while containing a minimum of 80%wt water.

Abstract: As device features scale down to 90nm and Cu/low-k films are employed for back end interconnects, post etch and ash residue cleaning becomes increasingly challenging due to the higher aspect ratio of the features, tighter CD control requirements, sensitivity of the low-k films, and the requirement for high wet etch selectivity between CuxO and Cu. Traditional solvent based cleaning in wet benches has additional issues such as wafer cross-contamination and high disposal cost [1, 2]. We have developed a novel aqueous solution (AQ) based single wafer cleaning process to address these challenges. The results of physical characterization, process integration electrical data, and process integration reliability data such as electromigration (EM) and stress migration data are presented. The main conclusions can be summarized as follows: (1) The single wafer cleaning process developed on the Oasis™ system can clean post etch residues and simultaneously clean the wafer front side and backside metallic contaminants; (2) In terms CuxO and Cu wet etch selectivity, CD loss control, the Oasis™ aqueous single wafer clean process is superior to the bench solvent cleaning process; (3)The Oasis aqueous cleaning process shows no undercut below etchstop due to the very low Cu etch amount in one cleaning pass, therefore the electromigration and stress migration performance of the aqueous Oasis processed wafers is clearly better than that of the solvent bench processed wafers.