The present invention relates to the field of semiconductor processing equipment. More particularly, the invention relates to the materials used in semiconductor equipment useful for the fabrication of integrated circuit devices, and in particular physical characteristics or properties of such materials to enhance the quality of the thin films deposited on the substrate to form circuit pathways for the integrated circuit and the recoverability of individual devices from a substrate.
Typical semiconductor processing equipment used in the fabrication of integrated circuit devices on substrates from which individual devices are retrieved includes a vacuum environment wherein individual device are created on the substrate and film layer deposition and pattern etch steps are performed to create circuit pathways to and from the device. The film layer formation steps are typically performed using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques, and the pattern etching typically involves the steps of resist deposition, patterning of the resist by lithography, and etching of the resist and underlying region such as a film layer in a plasma environment to form apertures therein/therethrough. In each process, any stray particles which deposit on the substrate can cause the region of the substrate on which they deposit to become defective.
One source of substrate particle contaminants in the processing equipment is from material which becomes deposited on the chamber components during the film layer deposition and etch steps. This material must be periodically cleaned from the chamber components before it becomes a nagging contaminant problem. Chamber cleaning is a time consuming process, during which substrates cannot be processed in the chamber.
Typically, to decrease the frequency at which the chamber walls must be cleaned, and thus decrease chamber downtime, the chamber components include shields which may be removed from the chamber and thereby exchangeable for clean shields after they have been contaminated with deposition material. Thus, the shields are sacrificed, but protect the chamber wall from the contaminants in the chamber. The shields may be recyclable.
Although the use of replaceable shields decreases the chamber downtime experienced during chamber cleaning, particles are still generated from the shields. The particles are primarily from two sources: extrinsic contaminants which are not removed from the chamber components prior to their placement into the chamber, and those formed by flaking off of deposition material formed on the chamber components during wafer processing. The flaking problem is often exacerbated by different coefficients of thermal expansion as between the chamber components and the contaminants. The contamination of substrates from particulate flakes from the shields, and other in chamber components, remains a substantial source of particle contamination in semiconductor fabrication equipment.
One approach to solving the problem of flaking has been to form a rough surface on the components, such as by grit blasting, thereby increasing the surface area to which a potentially contaminating material can adhere. However, it has been found that the blasting media itself, when adhered to the shield or other chamber element, can be a source of contamination once placed in the chamber and exposed to the wafer processing environment.
If a bead blasted surface is later covered with a deposition material, i.e., the surface is not a source of deposition material but merely a shield or other chamber component, the bead blasting material may not be a source of contamination. However, where the bead blasted surface is a deposition source, such as a sputtering target, the bead blasting material will likely become deposited on the substrate surface and thereby contaminate the substrate.
One solution to contamination caused by the blasting media has been to clean the blasted parts in an acid, thereby etching away any remnant blast material. However, this also reduces the surface roughness imparted to the part, thereby reducing the advantage imparted thereto by the blasting media, and also affects the tolerances on critical dimensions such as screw bores, etc.
Therefor, there exists a need in the art for a material which may be used in semiconductor fabrication equipment which includes the advantageous features of a blasted surface, without the negative, contaminating, effects of the blasting media.