Byoung-Jun Cho

Investigation of Source-Based Scratch Formation During Oxide Chemical Mechanical Planarization

The formation of scratches on silicon dioxide surfaces during chemical mechanical planarization in the semiconductor manufacturing process is a significant concern, as it adversely affects yield and reliability. In this study, scratch formation during CMP processing of the oxide surface was examined. The shapes of the resulting scratches were classified into three types: chatter mark type, line type, and rolling type. Chatter mark types were further subdivided into line chatter, broken chatter, and group chatter based on the shape. The effect of three different scratch sources (viz., pad debris, dried particles, and diamond particles) on scratch formation was comprehensively investigated. Chatter-mark-type scratches are predominant in the presence of agglomerated particles and pad debris. Group chatter marks are caused by the addition of pad debris. Unique scratch formation was observed on the wafer with different scratch sources. In particular, multiple-line-type scratches were observed in the presence of diamond particles.

Effect of Silicon Dioxide Hardness on Scratches in Interlevel Dielectric Chemical–Mechanical Polishing

In the silicon dioxide chemical–mechanical polishing (CMP) process, one of the most challenging issues is the formation of defects such as scratches. In this study, scratch formation behavior and CMP performance were evaluated on high-density plasma oxide (HDP), plasma-enhanced tetraethylorthosilicate (PETEOS), and borophosphosilicate glass (BPSG) wafers. To evaluate the number of scratches after the CMP process, contaminated abrasive particles were removed using an optimized post-CMP cleaning process consisting of scrubber cleaning and dilute SC1 megasonic cleaning. The oxide wafers were then treated with dilute hydrogen fluoride (HF) in order to improve the visibility of the generated scratches. The number and shape of the scratches were investigated as a function of oxide film hardness. The results show that a decrease in film hardness correlates with an increase in the number of scratches. Three different types of scratches (chatter marks, line, and rolling) were observed on the oxide surfaces. The dominant scratch shape on all three oxide films was chatter mark–type scratches. This could be attributed to the stick–slip phenomenon. However, the overall fraction of chatter marks compared to other types of scratches (especially line scratches) was proportional to the film hardness. It was also found that scratch depth was strongly influenced by the polishing pressure during CMP. The results clearly show that the mechanical pro- perties of the surface play a critical role in scratch generation.

Hybrid Cleaning Technology for Enhanced Post-Cu/Low-Dielectric Constant Chemical Mechanical Planarization Cleaning Performance

During chemical mechanical planarization (CMP), a copper/low-k surface is often contaminated by abrasive particles, organic materials and other additives. These contaminants need to be removed in the subsequent cleaning process with minimum material loss. In this study, a dilute amine-based alkaline cleaning solution is used along with physical force in the form of megasonic energy to remove particles and organic contaminants. Tetramethylammonium hydroxide (TMAH) and monoethanolamine (MEA) are used as an organic base and complexing agent, respectively, in the proposed solution. Ethanolamine acts as a corrosion inhibitor in the solution. Organic residue removal was confirmed through contact angle measurements and X-ray photoelectron spectroscopy analysis. Electrochemical studies showed that the proposed solution increases protection against corrosion, and that the hybrid cleaning technology resulted in higher particle removal efficiency from both the copper and low-k surfaces.

Effect of pH and chemical mechanical planarization process conditions on the copper–benzotriazole complex formation

Benzotriazole (BTA) has been used to protect copper (Cu) from corrosion during Cu chemical mechanical planarization (CMP) processes. However, an undesirable Cu–BTA complex is deposited after Cu CMP processes and it should be completely removed at post-Cu CMP cleaning for next fabrication process. Therefore, it is very important to understand of Cu–BTA complex formation behavior for its applications such as Cu CMP and post-Cu CMP cleaning. The present study investigated the effect of pH and polisher conditions on the formation of Cu–BTA complex layers using electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and the surface contact angle. The wettability was not a significant factor for the polishing interface, as no difference in the contact angles was observed for these processes. Both electrochemical techniques revealed that BTA had a unique advantage of long-term protection for Cu corrosion in an acidic condition (pH 3).

Investigation of Cu-BTA complex formation and removal on various Cu surface conditions

The effect of Cu surface conditions on Cu-BTA complex was investigated using ex-situ electrochemical impedance spectroscopy method. Cu-BTA complex is generated during Cu CMP process because BTA which is the most common corrosion inhibitor in Cu CMP slurry react with Cu and form a strong complex. Then it is very important to remove Cu-BTA complex during post-Cu CMP cleaning because Cu-BTA complex cause severe problem such as particle contamination and watermark due to its hydrophobic characteristic. The Cu-BTA complex formation at various Cu surfaces was investigated to understand its behavior, so the effective development will be possible in post-Cu CMP cleaning process.