The present invention generally provides a precleaning process prior to metallization for submicron features on substrates. The method includes cleaning the submicron features with radicals from a plasma of a reactive gas such as oxygen, a mixture of CF 4 /O 2 , or a mixture of He/NF 3 , wherein the plasma is preferably generated by a remote plasma source and the radicals are delivered to a chamber in which the substrate is disposed. Native oxides remaining in the submicron features are preferably reduced in a second step by treatment with radicals from a plasma containing hydrogen. Following the first or both precleaning steps, the features can be filled with metal by available metallization techniques which typically include depositing a barrier/liner layer on exposed dielectric surfaces prior to deposition of aluminum, copper, or tungsten. The precleaning and metallization steps can be conducted on available integrated processing platforms.

Reactive preclean prior to metallization for sub-quarter micron application

Due to continuous miniaturization and increasing number of electrical components in electronics, copper interconnections have become critical for the design of 3D integrated circuits. However, corrosion attack on the copper metal can affect the electronic performance of the material. Superhydrophobic coatings are a commonly used strategy to prevent this undesired effect. In this work, a solventless two-steps process was developed to fabricate superhydrophobic copper surfaces using chemical vapor deposition (CVD) methods. The superhydrophobic state was achieved through the design of a hierarchical structure, combining micro-/nanoscale domains. In the first step, O2- and Ar-plasma etchings were performed on the copper substrate to generate microroughness. Afterward, a conformal copolymer, 1H,1H,2H,2H-perfluorodecyl acrylate-ethylene glycol diacrylate [p(PFDA-co-EGDA)], was deposited on top of the metal via initiated CVD (iCVD) to lower the surface energy of the surface. The copolymer topography exhibited a very characteristic and unique nanoworm-like structure. The combination of the nanofeatures of the polymer with the microroughness of the copper led to achievement of the superhydrophobic state. AFM, SEM, and XPS were used to characterize the evolution in topography and chemical composition during the CVD processes. The modified copper showed water contact angles as high as 163° and hysteresis as low as 1°. The coating withstood exposure to aggressive media for extended periods of time. Tafel analysis was used to compare the corrosion rates between bare and modified copper. Results indicated that iCVD-coated copper corrodes 3 orders of magnitude slower than untreated copper. The surface modification process yielded repeatable and robust superhydrophobic coatings with remarkable anticorrosion properties.

Superhydrophobic Copper Surfaces with Anticorrosion Properties Fabricated by Solventless CVD Methods

https://ir.nctu.edu.tw:443/bitstream/11536/238/1/000071553400095.pdf

Effects of corrosion environments on the surface finishing of copper chemical mechanical polishing

The present invention relates generally to an improved process for providing uniform step coverage on a substrate and planarization of metal layers to form continuous, void-free contacts or vias in sub-half micron applications. In one aspect of the invention, a refractory layer is deposited onto a substrate having high aspect ratio contacts or vias formed thereon. A CVD metal layer is then deposited onto the refractory layer at low temperatures to provide a conformal wetting layer for a PVD metal. Next, a PVD metal is deposited onto the previously formed CVD metal layer at a temperature below that of the melting point temperature of the metal. The resulting CVD/PVD metal layer is substantially void-free. The metallization process is preferably carried out in an integrated processing system that includes both a PVD and CVD processing chamber so that once the substrate is introduced into a vacuum environment, the metallization of the vias and contacts occurs without the formation of an oxide layer over the CVD Al layer.

Low temperature integrated metallization process and apparatus

The main chemical aspects of the preparation of thin copper films from the vapour of monovalent and divalent copper derivatives as precursors in the CVD technique are considered. Data on the methods of synthesis and the properties of various types of these compounds are generalised and described systematically. The possible decomposition mechanisms of copper compounds under CVD conditions are discussed. The prospects of using the CVD technology for the preparation of thin copper films in integrated circuits of microelectronic devices are outlined. The bibliography includes 432 references.

Preparation of thin copper films from the vapour phase of volatile copper(I) and copper(II) derivatives by the CVD method

Copper metallization was applied to quarter-micron CMOS circuits using copper chemical vapor deposition (CVD) and chemical mechanical polishing (CMP). Both the metallization process and the electrical characteristics of CMOS devices/circuits were evaluated. Process-induced metal contamination on both sides of the wafer were quantitatively evaluated and reduced to about of 10/sup 11/ atoms/cm/sup 2/ by using an optimized cleaning sequence. The ability of borophosphosilicate-glass (BPSG) to act as a copper diffusion barrier was discovered and the ability of TiN to do so was also confirmed. Electrical characteristics of n and p MOSFET's with copper interconnections were stable even after annealing at 550/spl deg/C. The leakage current of the pn junction, capacitance-voltage characteristics and time-dependent dielectric breakdown characteristics of the MOS diode indicate that the copper metallization process did not deteriorate the pn junction and the gate oxide. Normal operation of a 53-stage quarter-micron CMOS inverter ring oscillator with copper metallization was successfully achieved.

Y. Arita

Papers

Evaluation of a copper metallization process and the electrical characteristics of copper-interconnected quarter-micron CMOS