**1. Introduction**

Chemical mechanical planarization (CMP) is a critical and enabling process to achieve nanolevel local and global planarization across 300 mm wafer in integrated circuit (IC) manufacturing [1–3]. There are three main applications of the CMP process in the semiconductor device manufacturing: the formation of the transistors (front-end-of-line, FEOL), the local connections between transistors (middleof-line, MOL), and the interconnect structures (back-end-of-line, BEOL). FEOL processes form the transistors and build the device architecture. One of the important FEOL CMP processes is the shallow trench isolation (STI) CMP. STI CMP uniformly polishes the step height of SiO2, formed by the gap-filling process, and stops on an underlying Si3N4 film [4–6]. MOL CMP processes include the necessary steps to connect the individual transistors by mainly polishing W contact metal/liner and interlayer dielectric (ILD) layer [7, 8]. BEOL processes enable the multilevel interconnect network where Cu lines are isolated by the dielectric materials [9].

CMP process is mainly utilized to achieve the desired removal rates, rate selectivity between exposed materials, uniformity, etc. by the synergistic interplay of chemical and mechanical interactions. During this process, the wafer is pressed against a polishing pad under the applied down pressure. The slurry is applied onto the center of the pad and is transported into the pad/wafer gap through the pores and grooves of the polishing pad while rotating the pad at high speed, which generates various chemical and mechanical actions at the slurry/pad-wafer interface (**Figure 1**) [1]. Many factors including CMP consumables (slurry, pad, wafer, conditioner, retainer ring, etc.) and their process/tool conditions can have an influence on the polishing performances (**Figure 1**) [1, 10, 11].

As CMP technology has grown by leaps and bounds over the past several decades, considerable progress has been made. However, the presence of CMPinduced defects that can cause device failure and the severe yield loss has become a major concern in the modern semiconductor manufacturing process [3, 12, 13]. Removable defects (residual particles, organic residues, foreign materials, metallic impurities, etc.) and non-removable defects (scratches, corrosion, dishing, erosion, delamination, etc.) are presented on the polished wafer surfaces. The removable defects, also known as CMP-related to contaminants, should be completely removed in the subsequent cleaning process while minimizing the further formation of non-removable defects [14, 15]. CMP consumables themselves can be the source of the contaminants during polishing and cleaning [13]. CMP slurries for the dielectric process are mainly composed of abrasive particles, pH adjuster, dispersant, passivation agent for high selectivity, and deionized water (DIW) [16] Metal CMP slurries contain the additional chemical reagents like oxidizer, chelating agent, corrosion inhibitor, etc. to control the electrochemical behaviors of metal films during polishing [16, 17]. Typical CMP slurry components are listed in **Table 1** [1].

#### **Figure 1.**

*Schematic of a typical CMP process and CMP consumables and conditions associated with CMP performances. Reprinted from Ref. [1] with permission from the Journal of Materials Research.*

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*Chemical Mechanical Planarization-Related to Contaminants: Their Sources and Characteristics*

buffers

etc.)

performance.

buffers.

Abrasive: Ceria/Silica

Dispersant & Surfactants.

pH adjusting agents such as HNO3, KOH, NH4OH, etc. and

Chemical agents for high selectivity (PAA, amino acids,

Other chemical agents for high polish rates and better

pH adjusting agent such as HNO3, KOH, NH4OH, etc. and

Oxidizer: H2O2, KIO3, Fe(NO3)3, K2S2O8, etc. Complexing agents: glycine, citric acid, etc. Corrosion inhibitors: Azole and its derivatives.

Considerable effort has been devoted to minimizing the formation of contaminants during polishing by optimizing CMP consumables and their process/tool conditions. As the minimum feature size has shrunk below 7 nm and beyond, the devices require more stringent conditions to achieve a smooth defect-free wafer surface. Thus, the demand for understanding of the origin of CMP-related to contaminants and their characteristics is increasing in both industrial and academic research. This chapter provides an overview of the origin and characteristics of various CMPrelated to contaminants that can be generated or presented on the wafer surfaces after CMP and post-CMP cleaning process. It also provides important insights into the cleaning chemistry to remove these contaminants during post-CMP cleaning.

*Typical CMP slurry components. Reprinted from Ref [1] with permission from the Journal of Materials* 

Some of the CMP related to contaminants, such as residual particles, surface residues, organic residues, and metallic impurities, are common to most CMP processes, which are directly associated with CMP consumables [3, 12, 13]. Various types of CMP-related to contaminants and their impacts in the semiconductor manufacturing process were summarized in **Table 2** [18]. These contaminants are presumably attributed to the chemical reactions of slurry components at the slurry/ pad-wafer interface. The sources and characteristics of the contaminants listed in

Abrasive particle is not only one of the main components in CMP slurries (**Table 1**) [16, 17], but also a common contaminant observed after all CMP processes (**Figure 2a**) [13]. Silica and ceria have been widely employed as abrasive particles for CMP processes [16]. The adsorption of silica abrasives on the films is driven by the electrostatic attractive forces between abrasives and films in a certain

The challenges related to post-CMP cleaning solutions are highlighted.

**2. CMP consumables-induced contaminants**

**Table 2** will be discussed in this section.

**2.1 Residual abrasive particles**

*DOI: http://dx.doi.org/10.5772/intechopen.94292*

Dielectric CMP: SiO2, Si3N4, Poly-Si, SiC,

SiCN, etc.

**Table 1.**

*Research.*

**Applications Slurry components**

Metal CMP: Cu, W, Co, Ta, TaN, Ti, Ru, etc. Abrasive: Silica/Alumina.

*Chemical Mechanical Planarization-Related to Contaminants: Their Sources and Characteristics DOI: http://dx.doi.org/10.5772/intechopen.94292*


#### **Table 1.**

*Emerging Contaminants*

performances (**Figure 1**) [1, 10, 11].

CMP process is mainly utilized to achieve the desired removal rates, rate selectivity between exposed materials, uniformity, etc. by the synergistic interplay of chemical and mechanical interactions. During this process, the wafer is pressed against a polishing pad under the applied down pressure. The slurry is applied onto the center of the pad and is transported into the pad/wafer gap through the pores and grooves of the polishing pad while rotating the pad at high speed, which generates various chemical and mechanical actions at the slurry/pad-wafer interface (**Figure 1**) [1]. Many factors including CMP consumables (slurry, pad, wafer, conditioner, retainer ring, etc.) and their process/tool conditions can have an influence on the polishing

As CMP technology has grown by leaps and bounds over the past several decades, considerable progress has been made. However, the presence of CMPinduced defects that can cause device failure and the severe yield loss has become a major concern in the modern semiconductor manufacturing process [3, 12, 13]. Removable defects (residual particles, organic residues, foreign materials, metallic impurities, etc.) and non-removable defects (scratches, corrosion, dishing, erosion, delamination, etc.) are presented on the polished wafer surfaces. The removable defects, also known as CMP-related to contaminants, should be completely removed in the subsequent cleaning process while minimizing the further formation of non-removable defects [14, 15]. CMP consumables themselves can be the source of the contaminants during polishing and cleaning [13]. CMP slurries for the dielectric process are mainly composed of abrasive particles, pH adjuster, dispersant, passivation agent for high selectivity, and deionized water (DIW) [16] Metal CMP slurries contain the additional chemical reagents like oxidizer, chelating agent, corrosion inhibitor, etc. to control the electrochemical behaviors of metal films during polishing [16, 17]. Typical CMP slurry components are listed in **Table 1** [1].

*Schematic of a typical CMP process and CMP consumables and conditions associated with CMP performances.* 

*Reprinted from Ref. [1] with permission from the Journal of Materials Research.*

**302**

**Figure 1.**

*Typical CMP slurry components. Reprinted from Ref [1] with permission from the Journal of Materials Research.*

Considerable effort has been devoted to minimizing the formation of contaminants during polishing by optimizing CMP consumables and their process/tool conditions. As the minimum feature size has shrunk below 7 nm and beyond, the devices require more stringent conditions to achieve a smooth defect-free wafer surface. Thus, the demand for understanding of the origin of CMP-related to contaminants and their characteristics is increasing in both industrial and academic research. This chapter provides an overview of the origin and characteristics of various CMPrelated to contaminants that can be generated or presented on the wafer surfaces after CMP and post-CMP cleaning process. It also provides important insights into the cleaning chemistry to remove these contaminants during post-CMP cleaning. The challenges related to post-CMP cleaning solutions are highlighted.
