Model of Particle Contact Area for Friction in Oxide Chemical Mechanical Polishing

Levert, Joseph A.; Korach, Chad S.; Mooney, Benjamin; Lynam, Franklin

doi:10.1149/2.0071909jss

Cited by 4 publications

(7 citation statements)

References 34 publications

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“…In the CMP process of the oxides, the input energy caused by the relative speed, the chemicals, and of contact is composed of energy, E f , thermal, E t , and vibration, E v . Among these components of energy, E f and E t participate at the MRR , and E v is dispersed in the surrounding environment [ 15 , 16 ]. According to Figure 1 , the MRR is dependent on the E f in the CMP process; however, the MRR is related to F f through the quantity removed per unit length.…”

Section: Resultsmentioning

confidence: 99%

“…While n ( v r ) increases, the E f also increases; however, the average F f decreases because the removed amount per unit time is prolonged with an increase in n( v r ). Moreover, the decrease in F f with growing n ( v r ) also takes place due to the support provided by the boundary layer between the wafer and pad formed as a result of the suspension flow via the pressure dynamic, p [ 16 ]. Figure 3 b shows the variation of F f and E f with various p of planarization/polishing at an n ( v r ) constant.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, during the friction process in the CMP, the change in the CMP process temperature becomes essential. The effects of the slurry nanoparticle concentration and size were investigated by many researchers [ 16 , 24 , 25 , 26 ], often with contradictory results, because it influences the MRR during the CMP process.…”

Section: Resultsmentioning

confidence: 99%

“…This change is caused by the motion modification of the nanoparticles, and an increase in their number leads to the load per nanoparticle decreasing when in contact with the wafer surface. Then, for the abrasive concentrations between 7.5 and 15 wt.%, the nanoparticles start to roll faster rather than slide on the wafer surface [ 16 ]. The surface AFM micrograph at 15 wt.% shows pitting deformations rather than scratches on the wafer surface, demonstrating the rolling motion of the abrasive nanoparticles ( Figure 6 b).…”

Section: Resultsmentioning

confidence: 99%

“…[ 15 ] analyzed the mechanical aspects of the MRR phenomenon, and Levert et al in ref. [ 16 ] researched the oxide’s influence on the friction force in the copper CMP process. Furthermore, they proved the dependence of the friction force on the nature of the oxide film generated by H 2 O 2 during copper CMP.…”

Section: Introductionmentioning

confidence: 99%

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The Effects of Friction and Temperature in the Chemical–Mechanical Planarization Process

et al. 2023

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Chemical–mechanical planarization (CMP) represents the preferred technology in which both chemical and mechanical interactions are combined to achieve global planarization/polishing of wafer surfaces (wafer patterns from metal with a selective layer, in this paper). CMP is a complex process of material removal process by friction, which interferes with numerous mechanical and chemical parameters. Compared with chemical parameters, mechanical parameters have a greater influence on the material removal rate (MRR). The mechanical parameters manifest by friction force (Ff) and heat generated by friction in the CMP process. The Ff can be estimated by its monitoring in the CMP process, and process temperature is obtained with help of an infrared rays (IR) sensor. Both the Ff and the MRR increase by introducing colloidal silica (SiO2) as an abrasive into the selective layer CMP slurry. The calculated wafer non-uniformity (WNU) was correlated with the friction coefficient (COF). The control of Ff and of the slurry stability is important to maintain a good quality of planarization with optimal results, because Ff participates in mechanical abrasion, and large Ff may generate defects on the wafer surface. Additionally, the temperature generated by the Ff increases as the SiO2 concentration increases. The MRR of the selective layer into the CMP slurry showed a non-linear (Prestonian) behavior, useful not only to improve the planarization level but to improve its non-uniformity due to the various pressure distributions. The evaluation of the Ff allowed the calculation of the friction energy (Ef) to highlight the chemical contribution in selective-layer CMP, from which it derived an empirical model for the material removal amount (MRA) and validated by the CMP results. With the addition of abrasive nanoparticles into the CMP slurry, their concentration increased and the MRA of the selective layer improved; Ff and MRR can be increased due to the number of chemisorbed active abrasive nanoparticles by the selective layer. Therefore, a single abrasive was considered to better understand the effect of SiO2 concentration as an abrasive and of the MRR features depending on abrasive nanoparticle concentration. This paper highlights the correlation between friction and temperature of the SiO2 slurry with CMP results, useful to examine the temperature distribution. All the MRRs depending on Ef after planarization with various SiO2 concentrations had a non-linear characteristic. The obtained results can help in developing a CMP process more effectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Effects of Friction and Temperature in the Chemical–Mechanical Planarization Process

et al. 2023

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Characterization of Pad–Wafer Contact Area and Distance in Chemical-Mechanical Polishing

Schumacher-Härtwig

2023

ECS J. Solid State Sci. Technol.

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Chemical-mechanical polishing (CMP) has been an important process step in microelectronic device manufacturing for more than three decades. Physical CMP modeling utilizes the interactions between the polishing pad and the wafer. This requires data on important physical properties such as the real contact area and the effective pad-to-wafer distance under near-process conditions, as these are directly related to the removal rate, defects, etc. In the present study, a FTIR spectrometer and a custom ATR equipment with micro-structured single reflection elements (mSRE) were used to quantify the volume fraction and contact area of a IC1000 polishing pad in dry and wet state under different static loads. No stable contact over time was observed even at very high pressures of up to 350 kPa. Viscoelastic behavior of an air-dried and water-soaked pad was proven on a microscale by using load response, creep-recovery and stress relaxation tests. This leads to a memory effect of the pad that should be taken into account during dynamic loading as the wafer-pad contact has a direct impact on the material removal. The presented method can therefore provide valuable information about dynamic effects of the pad behavior in near-process environment and thus help to improve the CMP modelling.

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Polishing Characteristics and Mechanism of Polishing Glass Substrate Using Suede Pad with Fine Micrometer-Sized Pores

Uneda¹,

Yamada²,

Tawara³

2022

IJAT

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Chemical mechanical polishing (CMP) using a suede polishing pad is an essential fabrication process for glass substrates that require ultra-high planarization. However, the effect of surface asperities of the suede pad on its polishing characteristics is not completely understood because the structure of the suede pad in the thickness direction is not constant, and its surface asperities can easily change during the pad conditioning or marathon polishing processes. In addition, many previous studies have discussed the polishing mechanism using a suede pad; however, these studies used suede pads with a pore size of approximately 100 μm. This paper discusses the polishing characteristics of a suede pad with fine micrometer-sized pores by clarifying the relationships between the removal rate, friction coefficient, pore parameters, and roughness as the pad surface asperities. In this study, a series of marathon polishing tests were performed with and without conditioning. It was discovered that the removal rate was affected not only by the pore parameters but also by the surface roughness of the suede pad with fine pores. The relationship between the removal rate and the friction coefficient changed owing to the influence of pad conditioning, and this change is significant when the break-in conditioning time is short.

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Model of Particle Contact Area for Friction in Oxide Chemical Mechanical Polishing

Cited by 4 publications

References 34 publications

The Effects of Friction and Temperature in the Chemical–Mechanical Planarization Process

The Effects of Friction and Temperature in the Chemical–Mechanical Planarization Process

Characterization of Pad–Wafer Contact Area and Distance in Chemical-Mechanical Polishing

Polishing Characteristics and Mechanism of Polishing Glass Substrate Using Suede Pad with Fine Micrometer-Sized Pores

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