An Alkaline Slurry Design for Co-Cu CMP Systems Evaluated in the Tribo-Electrochemical Approach

It has been difficult to remove BTA-related organic residues (BTA, Cu-BTA, and Co-BTA complexes) and silica abrasives from various surfaces during post Cu-CMP cleaning when Co is used as the liner. Here, we investigated the adsorption of these residues and their removal from Cu, Co, TaN and SiO 2 films for Cu interconnect applications. A 50 mM aqueous solution of ethylenediamine (En) at pH 11, aided by ultrasonic agitation, almost completely removed these contaminants adsorbed on only Cu and Co films. Cleaning was facilitated by the much higher stability constants of Cu-En/Co-En complexes compared to those of Cu-BTA/Co-BTA complexes, which led to their dissociation via ligand exchange. En also lowered E corr of the Cu/Co couple to ∼40 mV but their I corr values remained high. Cysteine (Cys) and uric acid (UA) were effective in controlling the cathodic and anodic reactions of Cu and Co films. An aqueous mixture of 0.75 mM Cys, 9.25 mM UA and 50 mM En at pH 11 not only removed the organic residues and silica particles from Cu and Co films but also lowered E corr between them to ∼5 mV with an I gc of ∼0.7 μA/cm 2 , acceptably low I corr values for both films with excellent surface quality.

mentioning

confidence: 99%

Post-CMP Cleaning Solutions for the Removal of Organic Contaminants with Reduced Galvanic Corrosion at Copper/Cobalt Interface for Advanced Cu Interconnect Applications

Seo

Vegi

Babu

2019

“…So, If the experiments had only been conducted under static conditions, the results would have been considerably misleading. 27 Thus, the electrochemical measurements under dynamic conditions could be an optimal way for representing the electrochemical mechanism during industrial production.…”

Section: The Effect Of Tt-lyk On Cu Electrochemical Measurements Unde...mentioning

confidence: 99%

Inhibition Effect of TT-LYK on Cu Corrosion and Galvanic Corrosion between Cu and Co during CMP in Alkaline Slurry

Pan

Zhang

et al. 2019

Cu corrosion and galvanic corrosion between Cu and Co are two challenging issues during the chemical mechanical polishing (CMP) process in the ultra large scale integration (ULSI) technology. The effect of novel inhibitor TT-LYK on Cu corrosion and galvanic corrosion between Cu and Co in alkaline slurry was investigated under both static and dynamic conditions. Various analytical techniques were used to elucidate the corrosion inhibition mechanism of TT-LYK on Cu. Results showed that both static etching rate (SER) and removal rate (RR) of Cu during CMP decreased with the increase of concentration of TT-LYK. From potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) measurements, it was found that the corrosion inhibition effect on Cu may result from the adsorption of Cu(I)-TT-LYK passivating film on Cu surface. In order to characterize the effect of galvanic corrosion, the corrosion potential difference ( E) between Cu and Co was measured during both static and dynamic condition. It was apparently seen from the results that the galvanic corrosion under dynamic conditions was significantly suppressed compared with the static cases. It revealed that if the experiments had only been conducted under static conditions, the results would have been considerably misleading.

“…Experiments designed along these lines can help to develop a mostly sample-independent framework to quantify the mechanistic correlations between surface adsorption, electrochemical tribo-corrosion and material removal in metal CMP. 29 …”

Section: New Challenges and Future Directionsmentioning

confidence: 99%

“…of fab based CMP. 29 However, the selection of suitable test samples represents a foremost challenge of mirroring the fab-CMP conditions in a typical laboratory setting.…”

Section: Limits and Utilities Of Laboratory Scale Model Cmp Systemsmentioning

confidence: 99%

“…As a result, probing the underlying triboelectrochemistry of CMP for a film WE is difficult. 29 Discs/coupons of bulk metals are more suited for tribological setups, but microstructurally they are not the best models of real device components. 32,33 Thus, within the practical confines of commonly available samplechoices, it is difficult to wholly emulate both the (electro)chemical and the mechanical aspects of fab-based CMP with laboratory compatible models.…”

Section: Limits and Utilities Of Laboratory Scale Model Cmp Systemsmentioning

confidence: 99%

See 1 more Smart Citation

Perspective—Electrochemical Assessment of Slurry Formulations for Chemical Mechanical Planarization of Metals: Trends, Benefits and Challenges

Roy¹

2018

Self Cite

With continued shrinkage of circuit dimensions, the technique of chemical mechanical planarization (CMP) has become progressively more intricate through the last decade. Since the chemical mechanism of metal CMP is governed by electrochemical effects, the complex task of CMP-slurry engineering can be economically assisted in the electroanalytical approach by using laboratory scale model systems. This article discusses how CMP has been impacted by device scaling, and examines the status of fundamental studies of metal CMP. The techniques suitable for studying model CMP systems are discussed, along with an assessment of the utilities and the practical limits of such experiments. Chemical mechanical planarization (CMP) is an essential processing step of integrated circuit (IC) fabrication. 1,2 CMP of the metal components of logic devices constitute a major aspect of this technique and, like other areas of IC manufacturing, metal CMP has become quite complex while addressing the emerging demands of technology through the last decade. 3 The new challenges of metal CMP originate from both the scaling and the novel material aspects of these systems. 3,4 At the same time, published reports indicate that, many of these issues, especially those related to the slurry consumables, 5 can be addressed to a large extent through electroanalytical examinations of slurry functions using scaled down models of actual CMP systems. 6 Recent studies performed in industrial facilities have also identified a critical need to further advance the fundamental understanding of metal CMP. 7,8 The present article provides a perspective on these fundamental research aspects of metal CMP that are in the core of most laboratory scale studies of these systems. Device Scaling and CMP ConsiderationsThe International Technology Roadmap for Semiconductors (ITRS) specified the earlier technology nodes in terms of the DRAM half-pitch (hp), or the microprocessor's level-1 metal hp of a device. 9 Basically until the 65 nm node, the shrinkage of feature-size has continued in line with Dennard scaling, by a factor (S) of 1/ √ 2, to accommodate doubling of transistors per unit chip area (scaling as S 2 = 1/2) every two years in relation to Moore's law. 10 Increased leakage currents in the subsequent feature reductions have eventually shifted this technology trend, with the emergence of advanced multicore systems. 11 While the scaling factor of 1/ √ 2 has been largely maintained in the post-Dennard period, the newer logic devices have evolved in a more complex manner compared to their earlier counterparts. The middle-of-line (MOL) metallization scheme has emerged from the need to reduce the parasitic effects of active wiring that extends over 4 km cm −2 for >13 metal layers. 9 Novel diffusion barriers and ultra-low-k (ULK) dielectrics, Fin field effect transistors (Fin-FETs), high-k gate dielectrics, and exploratory designs/materials for local interconnects have been steadily incorporated in new device architectures in keeping with the advents of scaling sch...