Rework and Removal of C-based Materials –
A challenge not only for semiconductor manufacturer
The deposition of carbon-based materials plays a major role in semiconductor industries. Lithography is not possible without the related photoresists. Residue free cleaning of C-based materials always was and will be challenging, even more with the industry moving towards advanced material, e.g., low-k materials, C-doped oxide, diamond like carbon (DLC), diamond. As the market of diamond deposition and laboratory grown diamond is constantly growing, it is critical to have the proper tool to clean off the residuel black carbon without damaging the diamond structure.
Microwave Plasma – Isotropic cleaning means soft and efficient cleaning
Due to its nature, the RF-plasma exposes the substrate to an energetic interaction with the plasma. Ions accelerating towards the substrate result in physical damage and contamination of the materials to be cleaned. in the removal of black carbon on diamond just a little amount of RF-bias may cause damage of the crystal structure and consequentially, irreversible discoloration. In contrast, microwave assisted plasma systems are capable to clean fast, efficient and with no impact to the substrate1.
Using MUEGGE’s microwave assisted plasma systems, the energy transfer to the substrate is extremely low, no ions are released into the process chamber. As a result, the substrate remains untouched, the active cleaning mechanism is the chemical reaction with black carbon or other carbon based residues. As the reaction is purely isotropic, no direct exposure of the residues to the plasma is required, which makes it extremely favorable for any 3D structures like MEMS or MMS.
1 Amorn THEDSAKHULWONG and Warawoot THOWLADDA. Journal of Metals, Materials and Minerals. Vol. 18 No. 2 pp. 137-141, 2008
MUEGGE’s solution – STP Product Family
- Microwave assisted plasma efficiently uses the energy to form highly reactive, neutral particles called radicals. No ions being released into the process chamber, no damage nor contamination of the substrate is created. Therefore the MW-assisted remote plasma system is ideal for black carbon removal on diamonds or DLC. Visual aspect and physical properties of the substrate are preserved.
- The radicals released from the MW assisted plasma guarantee smooth, pure chemical cleaning. As a consequence, the physical impact is extremely low and isotropic residue removal prevents further damage of the substrate material.
Microwave assisted plasma for removal of C-based materials
As shown in Figure 1, the radical-only formation results in little to no interaction with the substrate and the plasma chamber (low temperature), no ions in the chamber means contamination free processing. The pure chemical cleaning process can be fine-tuned without need to take physical etching into consideration.
Advantages of microwave assisted plasma cleaning
Microwave-assisted plasma allows to remove carbon based residues as well as black carbon for semiconductor applications and diamond processing.
Due to the physical properties, MW assisted plasma is specially designed for fast but smooth etching without the typical ion-attack observed for RIE systems (RF-based plasma). The radicals generated in the plasma initiate the chemical reaction at the surface only. Without measurable electrical fields and ions present at substrate level, no ion-induced physical damage occurs.
MW assisted plasma is highly environmentally compliant due to highly efficient dissociation of process gases like CF4 and NF3.