Jerome Daviot

Molecular design for inhibition of titanium corrosion in resist cleaner systems

Abstract A range of substituted catechols and pyrogallols are examined as corrosion inhibitors for titanium during processing with resist cleaners in the microelectronic industry. The corrosion inhibition is consistent with an adsorption mechanism and the best predictor for inhibition performance is found to be the hydrophobicity of the molecule. The trihydroxybenzenes adsorb more strongly on the titanium surface than the corresponding dihydroxybenzene compounds. It is also shown that trace quantities of calcium act as an extremely effective inhibitor. Consequently, calcium levels in the organic material must be reduced to less than ≈2 ppm before measurement of the inhibition efficiency.

Advanced Aqueous Cleaner II: PER Removal from Sensitive Cu/Low-k Devices

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.

Copper decontamination ability of supercritical-CO2/additives on CVD and spin-on porous MSQ materials

The paper focused on the development of very dilute mixtures of chelating agents, acids and organic solvents for post etch residue (PER) removal and copper (Cu) low-k decontamination under supercritical CO 2 (SCCO 2 ) foradvanced nodes (< 65nm) BEOL integration. The Cu low-k decontamination ability of each mixture was carried out on Spin-On Dielectric (SOD) and Chemical Vapor Deposition (CVD) porous low-k. The copper decontamination ability of SCCO 2 /additives systems were also studied on ashed and unashed low-k blanket wafers. Finally, the paper presented the Cu decontamination performance and Cu PER removal ability of SCCO 2 /additive systems compared to conventional wet chemistries.

Customized Chemical Compositions Adaptable for Cleaning Virtually all Post-Etch Residues

A post-etch residue cleaning formulation, based on balancing the aggressiveness of hydrofluoric acid with its well-known residue removal properties is introduced. In a series of investigations originally motivated by the cleaning challenge provided by high-k dielectric-based residues, a formulation platform is developed that successfully cleans residues resulting from the plasma patterning of tantalum oxide and similar materials while maintaining metal and dielectric compatibility. It is further shown that the fundamental advantages of this solution can be extended to the cleaning of other, more traditional post-etch residues, with no sacrifice in compatibility, as demonstrated by measurements on blanket films and through SEM data.

Low Undercut Ti Etch Chemistry for Cu Bump Pillar under Bump Metallization Wet Etch Process

This paper demonstrates how a low undercut Ti etchant developed by Technic France can be successfully introduced in a high volume manufacturing Fab for etching the under bump metallization (UBM). The Ti etchant has been tested on 300mm wafer production equipment in GLOBALFOUNDRIES. The Ti etchant evaluation has been carried out in collaboration with the Fraunhofer IZM-ASSID institute.

Process Dependence on Defectivity Count on Copper and Dielectric Surfaces in Post-Copper CMP Cleaning

At critical dimensions of 65nm and lower, the tolerances for yield impacting “killer” particle defects become ever tighter and this is especially true for Cu PCMP cleaning. This is a critical step in reducing wafer defectivity and metal contamination directly impacting yield and reliability. A successful candidate must exhibit a number of additional attributes not least of which are compatibility to Cu while selectively removing copper oxides (CuOx), and be fully compatible with porous ULK and barrier materials. Conventionally PCMP cleans typically require two different acidic or alkaline solutions containing a surfactant to drive particle removal and surface metal preparation; however this is not without its limitations e.g. crack propagation, water absorption, low-k wetting, water marks and galvanic corrosion. It would be advantageous if Cu PCMP could be performed with a single neutral pH cleaning solution. The paper will present results of work conducted on a neutral, single step Cu Post CMP (PCMP) cleaning solution, EKC PCMP5510™, and will discuss the influences of different process parameters in optimising defect removal from Cu and Ultra Low-K (ULK) dielectric surfaces (K=2.5) thus highlighting the fundamental differences in cleaning either surface.

Advanced Aqueous Cleaner I, Dilute Solutions for the Selective Removal of Post Etch Residues in the Presence of Aluminium

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.