Papers by Keyword: Single Wafer

Abstract: A single wafer silicon nitride (SiN) selective etch process with an etch rate greater than 80A/min of low-pressure chemical vapor deposited (LPCVD) SiN has been developed. Previous work with a similar single wafer system utilized a mixture of sulfuric acid, phosphoric acid and steam to achieve a high SiN etch rate [1]. The process in this work relies on phosphoric acid and steam for a high SiN etch rate. In both of these applications, addition of steam doubles the SiN etch rate. The single wafer system utilizes a closed chamber design with integrated spray bar to uniformly dispense hot phosphoric acid and steam onto the wafer surface achieving within wafer non-uniformities of less than 3%. Rinsing and drying of the phosphoric acid from the wafer surface occurs in the same chamber (dry in/dry out) providing a stable, haze free wafer. Figure 1 contains a schematic of the phosphoric acid delivery and single wafer system.

Abstract: Selective etching of silicon nitride films has been an important process step in integrated circuit manufacturing for many years [1-. In the past, this process has been mainly used to remove the silicon nitride mask which protects the transistor active area during the formation of oxide isolation. Recently, this process has also been used to remove silicon nitride spacers after source and drain formation for better management of the strained channel [. Advanced device integration continues to add more steps in which the selective removal of silicon nitride is needed.

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: In this paper, a single wafer linear IPA vapour based vertical drying technique is presented. Using salt residue tests the performance of this technique is evaluated and compared to spin drying. The equivalent film thickness of evaporating liquid is below 0.05µm for blanket wafers, which is two orders of magnitude less than with spin drying. It is also shown that the presence of surface topography (200nm high TEOS features on Si covered with a chemical oxide) does not significantly influence the drying performance. A study of the process window shows that for the setup evaluated in this work best performance is achieved when the IPA/N2 flow rate is above 20 liters per minute and the drying speed is below 8 mm/s. With a manual prototype already very good particle performance is demonstrated.