Cu Interconnects Research Articles

Study on Oxygen Plasma-Based Copper Etching Process

Abstract A plasma-based, room-temperature copper etch process using the chlorine- or bromine-containing feed gas was reported. This simple process could potentially replace the chemical mechanical polishing method in preparing copper interconnects. However, the chlorine- and bromine-containing gases are corrosive and must be handled with expensive equipment following stringent safety procedures. In this paper, the oxygen plasma-based copper etch process is presented. The copper film was converted into a porous and polycrystalline copper oxide film which was subsequently dissolved in a dilute hydrochloric acid solution. The copper film was expanded when converted into an oxide film. The oxidation precursors, i.e., oxygen radicals and ions, were generated in the plasma phase and then transported through the oxide layer to the underneath copper film where the oxidation reaction proceeded. The oxide growth rate is affected by plasma parameters, such as pressure and power, and the kinetics of the oxidation reaction. This new oxygen plasma-based process is a simple solution for preparing copper interconnects for nano and microelectronic products.

Improved Conductivity of Low‐Temperature‐Synthesized Graphene/Cu for CMOS Backend‐of‐Line Interconnect Applications

AbstractThis study proposes a synthesis strategy of high‐quality graphene films on the copper foil at a temperature of 400 °C throughout the graphene growth process without employing high‐temperature annealing. Through continuous CO2 laser pretreatment of the copper foil, the surface smoothness improves, and the removal of copper particles and copper oxide results in fewer defects on the foil. Therefore, the nucleation density of graphene is reduced, leading to a more uniform and continuous graphene film and showing an outstanding quality of graphene with low defects and low resistivity compared with other groups. After laser treatment, the copper foil's resistivity decreases from 1.71 ×10−8 to 1.51 ×10−8 Ω·m. The graphene‐coated on laser‐treated foil experiences an even more substantial decrease in resistivity, from 1.34 ×10−8 to 1.18 ×10−8 Ω·m, marking a significant 11.94% reduction. Excitingly, the groundbreaking technique is taken to the next level by applying it to fine copper interconnects as narrow as 0.4 µm. The experiments confirm the successful cultivation of graphene on these miniature scales, showing the immense potential of the approach. The proposed approach aligns with the demands of contemporary CMOS backend‐of‐line processes, facilitating the seamless incorporation of graphene in advanced chip technologies.

Effect of hydrogen on the integration process of photosensitive polyimide and its feasibility in advanced packaging

To reduce the resistive-capacitive (RC) delay, low-k materials are employed in advanced packaging systems that cover the redistribution layers (RDL). Owing to its remarkable properties, photosensitive polyimide (PSPI) is one of the most widely used interlayer dielectric (ILD) materials. Industries usually employ the forming gas annealing (FGA) (5 % H2 / 95 % N2 at 350 °C) in processes which help to reduce the dangling bonds at interfaces of Si/SiO2. Considering this, we have studied the effect of FGA onto photopatterned PSPI films and compared it with nitrogen gas annealing. The imidization in films at different ambientes is confirmed by Fourier Transform Infrared Spectroscopy (FTIR). X-ray photoelectron spectroscopy (XPS), and Elemental Dispersive Spectroscopy (EDS) implied to study the compositional change in PSPI after different ambient annealing. Our study reveals that FGA causes more imidization, but it forms impurities in PSPI leading to reduction in its mechanical strength and causes carbon from PSPI to diffuse inside copper interconnects. We hope the proposed research will help to understand the adverse effect of FGA annealing on the PSPI. Interestingly, N2 gas annealing is more feasible for PSPI than that of FGA 350 °C.

Effect of novel non-inhibitor slurry on chemical mechanical polishing properties of copper interconnect copper film based on experiments and theoretical calculations

In order to simplify the component of copper slurry during chemical mechanical polishing (CMP) and improve the surface corrosion inhibition efficiency, anionic surfactant dodecylbenzene sulfonic acid (DBSA) and nonionic surfactant decyl glucoside (DG) as mixed surfactants were used instead of inhibitors, and the corrosion inhibition properties were thoroughly studied by experiments and theoretical calculations. Polishing experiments and surface morphology tests show that the mixed surfactants can effectively enhance the surface quality after CMP compared with traditional inhibitor TAZ. Electrochemical experiments show that DG and DBSA can form a dense passivation film on the Cu surface to prevent corrosion. The inhibition efficiency of mixed surfactants is as high as 95 %. The theoretical calculations indicate that DBSA and DG form a stable long-chain structure, which leads to a higher adsorption energy, a denser passivation film, and stronger corrosion inhibition, in agreement with the experimental findings. These studies confirmed the stronger inhibitory effect of mixed surfactant on Cu film CMP and provided a new reference for the design of simplified slurry without inhibitor components.

Effects of organic compounds rich in phosphate functional groups as multifunctional inhibitors on copper film chemical-mechanical polishing properties: Combined experiment and theoretical calculation

For copper (Cu) interconnection chemical mechanical polishing (CMP) process, the Cu film slurry follows the principles of high efficiency, environmentally friendly and low cost. In this study, hydroxyethylene diphosphonic acid (HEDP), amino-trimethylene phosphonic acid (ATMP) and ethylenediamine etramethylenephosphonic acid (EDTMP) were used as green inhibitors to study the effects of organic compounds rich in two, three and four phosphate functional groups on the corrosion inhibition properties of Cu films. The results indicated that the Cu film material removal rate (MRR) of HEDP reaches 5879 A/min and the surface roughness (Sq) is 0.85 nm, superior to the other two inhibitors. Through mechanical action analysis, electrochemical experiment, UV-Visible, X-ray photoelectron spectroscopy (XPS) test analysis and theoretical calculation, it was observed that three inhibitors could not only form stable complexes with Cu, which have the effect of corrosion inhibition, but also play a lubricating role of surfactant, and simplify the composition of slurry, and the inhibition efficiency order of them is HEDP > ATMP > EDTMP.

Effect of Superfilling and Leveling Inhibitors in Hybrid Additives on the Microstructure Evolution of Electroplated Copper Interconnect Films during Self-Annealing

Abstract As the feature size shrinks, the main challenge for copper interconnect electroplating is to minimize interconnect resistance while ensuring the void-free feature filling, which is realized by the interaction of additives during electroplating. Among additives, hybrids are considered suitable for damascene filling because they combine type-I (superfilling) and type-II (leveling) inhibitors. However, it is generally believed that the more inhibitory an additive is, the more impurities it introduces into the films, thereby hindering grain growth during self-annealing, which paradoxically limits the conductivity of copper interconnects. To balance the inhibition of hybrid additives with their ability to introduce impurities, the effect of hybrid additives on the microstructure evolution of the films during self-annealing is explored in terms of texture, grain size, and impurity density, which are considered to determine the conductivity of copper films. We find that the {111} texture increases as the percentage of type-I inhibitors increases, whose relative texture coefficient reaches 97% after self-annealing due to the adsorption of hybrid additives on non-<111>-oriented crystal planes. Additionally, the impurity content and grain size increase as type-I inhibition increases, and so does the film conductivity after self-annealing, due to the possible promotion from impurities to the grain growth.

Stress-induced warpage estimation of advanced semiconductor copper interconnect processes

The growth of the semiconductor industry is driven by the demand for electronic products and high transistor density. However, complex manufacturing processes generate residual stress and result in wafer warpage. Therefore, mastering wafer warpage has become a crucial challenge. This study proposes a process-oriented simulation methodology with simulation-based equivalent material method to overcome the difficulty of finite element modeling and the substantial amount of computation time. Three different methodologies, including volume percentage, representative volume element, and Timoshenko bi-material approach, are discussed due to the estimation of residual stress for equivalent material. In addition, each methodology is validated through process-oriented simulations and comparison with measurement data. The Timoshenko bi-material approach is efficient in predicting warpage in the back end of line (BEOL) interconnects and provides a comprehensive understanding of the warpage variation that occurs during different stages of BEOL.

Investigation of Optical Interconnects for nano-scale VLSI applications

The relentless trend toward miniaturization has brought interconnects to the brink of communication bottlenecks, operating at or near their ampacity (current carrying capacity) limits. This degradation in performance necessitates novel technologies with increased ampacity. This study explores optical interconnect (OI) as a potential future technology, offering high-bandwidth communication and low latency. This study models and simulates OI, integrating recent optical device advancements with modest modulator and detector capacitance (50 fF). Performance metrics including signal delay, power dissipation, and power-delay-product (PDP) are compared across copper (Cu) and single-wall carbon nanotube bundle (SWCNT-B) interconnects at 22 nm and 14 nm technology nodes. Results consistently show OI, with an active voltage current feedback (AVCF) based regulated gain cascode (RGC) transimpedance amplifier (TIA) receiver, outperforms Cu and SWCNT-B interconnects at global lengths and beyond. For instance, at 1000 μm and 22 nm, OI exhibits 88.47 % and 62.15 % delay improvements over Cu and SWCNT-B, respectively. This trend persists at 14 nm, with OI showing 93.68 % and 84.29 % delay improvements, respectively. Additionally, OI surpasses Cu and SWCNT-B in power efficiency beyond a critical length. As interconnects extend to global scales and beyond, the differences in delay, power, and PDP between OI and electrical interconnect increases, highlighting OI's advantages for future VLSI IC applications.

Corrosion inhibitors in H2O2 system slurry for Ru based barrier layer Cu interconnect chemical mechanical polishing and optimization

Ruthenium (Ru) has the advantages of low resistivity, high thermal stability, and good adhesion and wettability, making it an important solution for breaking through the 14 nm process as a new barrier layer material for multilayer copper interconnect. The purpose of copper (Cu) interconnect Ru-based barrier layer chemical mechanical polishing (CMP) is to obtain a highly flat surface, which not only includes the ideal Ru removal rate and selectivity of the Cu/Ru removal rate, but also inhibition of Cu corrosion. In this article, the corrosion inhibition mechanism of environmentally friendly and highly water-soluble inhibitor 5-methylthio-1 H-tetrazole (MTT) on Cu was studied. The inhibitory effect of MTT on Cu was analyzed through static etching rate testing, electrochemical experiments, and surface characterization. A systematic test was conducted on the planarization performance of the optimized polishing slurry. The corrosion inhibition mechanism of MTT on Cu was revealed through quantum chemical calculations and XPS testing. The experimental results show that the corrosion inhibitor MTT can effectively improve the surface quality of Cu. Quantum chemical calculations and experimental results indicate that MTT can be adsorbed on the surface of Cu through both physical and chemical methods, forming a dense passivation film, thereby inhibiting the corrosion of Cu. The optimized ratio of Ru-based barrier layer CMP polishing slurry was 5 wt% SiO2, 0.15 wt% H2O2, 20 mM ethylenediamine (EDA), 5 mM K4Fe(CN)6, and 2000 ppm MTT, resulted in the Cu/Ru removal rate selectivity of 1:1.18 and the Cu/Ru corrosion potential difference of 3 mV. The average correction values for dishing and erosion on the test pattern wafer of the Ru barrier layer were 355 Å and 280 Å, respectively. The results of this study indicate that MTT is an effective copper corrosion inhibitor in alkaline H2O2-based polishing slurry, providing meaningful references for Ru-based barrier layer copper interconnect CMP.

Bio‐Inspired Hybrid Laser Direct Writing of Interfacial Adhesion for Universal Functional Coatings

AbstractEnhancing interfacial adhesion between functional coatings and target surfaces facilitates long‐term stable service by mitigating interferences of mechanical mismatches. Design of mechanical interlocks affords an effective strategy to strengthen the interfacial bonding with durability and compatibility, but the in‐depth investigations are still lacked. Herein, a gecko‐inspired hierarchical strategy realized by hybrid laser direct writing is proposed, which incorporates an armored frame scale for surface protection and a riveted anchor scale for interlocks. Such dual‐scale configurations endow the functional coatings with the stronger adhesion to the targets than the pristine and mono‐scale cases, resulting in 2 orders of magnitude enhancement resistant to tape peeling tests. Utilizing this scheme, a laser‐induced integrated deicing system is in situ manufactured on thermoplastics, primarily comprising superhydrophobic structures, carbon‐based sensors as well as adhesive copper (Cu) interconnects and heaters, where Cu‐based devices exhibit superior resistance to water impacts and stress fatigue. Interfacing with signal processing modules, such an all‐in‐one system demonstrates real‐time temperature monitoring and high efficiency in deicing (4.24 folds faster than the control group). The facile route for intensified adhesion holds promise in the interfaces within advanced equipment and under harsh scenarios.

CMP: Four Decades of Innovation and a Promising Future

The invention of CMP by IBM in 1983 represents an inflection point in the evolution of semiconductors. It was a bold and risky idea to mechanically apply abrasives to the surface of a wafer, but this new process for restoring a wafer to a planar state was the key to continued areal scaling and increased device complexity. Initially applied to a simple application for filling trenches with insulator, the potential of this technique was evident. Through understanding of material properties and subsequent manipulation of slurry chemistry, CMP was applied to enable the more challenging and technically critical processes for Shallow Trench Isolation and Tungsten contacts. The late 1990’s saw the introduction of copper interconnects. IBM was first to market this technology which continues to support conductors down to lines widths on the order of 10 nanometers! The CMP process required for copper interconnects demanded a thorough understanding of the materials present and potential surface phenomena for exploitation. For this need, a new and complex mechanism for copper planarization was invented. Equally challenging was the need for a subsequent non-selective barrier removal step. For this a unique, self-balancing approach was also invented, borrowing some elements from previous STI technology. Device architecture has progressed from planar geometry to FINFETs to Gate All Around, or Nanosheet technology. This evolution has required increasingly more CMP process steps with a concurrent demand for increased process control. Gate height control for Nanosheeets is currently paramount for performance, affected by many CMP steps in the process flow. A typical requirement is less than 1nm added variability per CMP step! Looking forward, CMP continues to be tapped to enable technology evolution. Polish steps are becoming part of the patterning process to enable pitch splitting for upcoming nodes. A VTFET integration approach can enable further area scaling but presents integration challenges; CMP is being asked to enable “third color” schemes for the protection of NFET vs PFET devices which is necessary at various points in the in the VTFET process flow. Heterogeneous Integration is demanding nanometer control of topography across large contact pads and large lateral distances. Finally, extreme scaling is creating fundamental challenges for metal polish at the contact and interconnect levels. CMP tool architecture currently does not provide for control of ambient conditions at the wafer surface during wet transport and post CMP cleaning. Subsequently, unwanted metal dissolution is observed. New tool designs will be needed to control wafer surface conditions, and particularly oxygen exposure through all steps within the CMP tool. This talk is dedicated to the special session in honor of Professor S.V. Babu

Effect of Thickness and Sidewall Slope of Photoresist Mask on Etch Profile of Copper Interconnect

We performed high density plasma reactive ion etching of copper thin films using organic gas mixture to define fine patterns less than 10 μm for the application of display devices. However, since redeposition in dry etching of copper thin films frequently occurs due to extremely low reactivity, the etch variables which affect the formation of redeposition were investigated. In this study, the photoresist (PR) masks were employed to etch copper thin films. The effects of the thickness of PR and the sidewall slope of PR on etch profile and redeposition were examined.The thickness of PR mask were in the range of 3 μm ~ 1 μm and the sidewall slopes of the PR mask were in the range of 90° ~ 45°. The etch profile and etch mechanism of dry etching using different masks were evaluated using field emission scanning electron microscopy and X-ray photoelectron spectroscopy. Finally, an etching method to reduce and/or avoid the redeposition in dry etching of copper thin films will be proposed.Acknowledgement : This research was supported by the MOTIE(Ministry of Trade, Industry & Energy (20019504) and KSRC(Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device.

Modeling and analysis of crosstalk induced effects in graphene-carbon nanotube composite interconnects

This paper proposes an equivalent circuit model for two-line coupled multilayer graphene nanoribbon - single-wall carbon nanotube (MLGNR-SWCNT) composite interconnects (MSCs), incorporating the effects of coupling capacitance and mutual inductance. We also examine the temperature-dependent crosstalk effect on the victim line of MSCs in the time domain using decoupling techniques and the ABCD parameter matrix approach. This analysis is conducted at the global level of 7 nm, 14 nm, and 22 nm technology nodes, comparing the performance of MSCs with MLGNR, SWCNT, and copper (Cu) interconnects, validated through HSPICE simulations. Our results reveal that the crosstalk delay of all interconnects induced by dynamic crosstalk exhibits superior performance in the in-phase crosstalk mode compared to the out-of-phase mode at room temperature. In particular, MSCs demonstrate less crosstalk delay in both crosstalk modes compared to SWCNT and Cu interconnects. In addition, we analyze the crosstalk delay of the victim line for two-line coupled MSCs at varying temperatures in out-of-phase crosstalk mode, comparing them with MLGNR, SWCNT, and Cu interconnects. Simulation results indicate that the crosstalk delay is temperature-dependent, increasing with rising temperatures, and the crosstalk delay of MSCs is the least of all interconnects. Furthermore, we investigate the crosstalk noise of MSCs induced by functional crosstalk at different temperatures, comparing it with MLGNR, SWCNT, and Cu interconnects. It is observed that the crosstalk noise peak remains constant with temperature changes across all interconnects; however, the holding time and width of crosstalk noise increases with rising temperatures and MSCs have the least crosstalk noise peak and crosstalk noise width of all interconnects. Also, numerical results exhibit that reducing interconnect temperature, SWCNT diameter, and edge roughness of MLGNR are effective strategies to diminish the crosstalk delay of MSCs. In addition, increasing line spacing is identified as an effective method to reduce crosstalk noise peak of MSCs of different lengths. The proposed model results show excellent agreement with HSPICE simulation data. Therefore, our analysis of crosstalk effect manifests that MLGNR-SWCNT composite can be a promising material to replace SWCNT and copper as an ideal material for global interconnect applications in thermally variable environments.

The feasibility of an ultrathin dual-barrier scheme to inhibit interfacial diffusion and reactions in contact stacks of Co/NiSi/Si

Self-assembled monolayers (SAMs) and self-forming barriers (SFBs) are highly effective barriers of copper (Cu) interconnect systems. However, the barrier capability of SAMs and SFBs to contact metallization of cobalt (Co), a new important interconnect material, is yet to be explored. Here, contact layers of NiSi are grown by a two-step silicidation process on Si. Then, an all-wet SAM-seeding and electroless-plating process is used to coat (in sequence) an amine SAM and a MnO-added (only 0.1%) Co film onto NiSi/Si, using a specifically formulated N2H4-CoSO4-MnSO4 bath. The thermal stability of the Co(MnO)/SAM/NiSi/Si is evaluated, using (unalloyed) Co/SAM/NiSi/Si as a control. The 1.3 nm-thin SAM cannot protect the Co/SAM/NiSi/Si from catastrophic failure upon annealing, associated with serious Co/Si interfacial diffusion and the formation of faceted CoSi crystallites and a layered Co2Si/CoSi2 nanostructures at specific locations. By contrast, the Co(MnO)/SAM/NiSi/Si maintains an intact stack after annealing. Collaborative research results generated from (scanning) transmission electron microscopy, nanoscratch testing and surface-energy measurements suggest that the thermal stability enhancement of the whole Co(MnO)/SAM/NiSi/Si contact stack is related to the interfacial segregation of the added MnO as sub-5-nm dispersive crystalline particles, giving multiple functionalities as a SFB, Co-grain strengthening agent, and wetting/adhesion promoter.

Cleaning mechanisms during post chemical mechanical polishing (CMP) using particle removal of surfactants via a citric acid-based solution

With the development of circuit integration technology, the requirements for defects in copper interconnects have become more stringent. The residual SiO2 particles on the copper surface can seriously affect circuit performance and require more efficient and thorough removal. This article investigates the effects of a novel cleaning solution composed of citric acid (CA), alkyl polysaccharide glycosides (APG1214), and dodecylbenzene sulfonic acid (LABSA), aimed at improving the removal efficiency of SiO2 and maintaining the integrity of copper surface. The optimal concentrations of APG1214 and LABSA were determined through contact angle and surface tension analysis. It was found that when APG1214 (2000 ppm) and LABSA (1000 ppm) were combined in a 3:2 vol ratio in CA solution (0.6 wt%), the highest particle removal efficiency (99.5 %) could be achieved while minimizing surface roughness. The results of scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed these findings. Combining quantum chemical calculations, new insights into the mechanism of action of different components in clean solutions have been proposed: 1. Similar to CA, LABSA and APG1214 demonstrate a strong affinity for copper, synergistically facilitating the cleavage of Cu-Si bonds. 2. Alternating adsorption of LABSA and APG1214 on free silica particles prevents their re-adsorption onto copper surfaces. 3. Furthermore, their orderly adsorption on copper mitigates the corrosive chelation effect of CA, providing a protective mechanism. These findings are pivotal for the development of advanced, multifunctional cleaning solutions.

Electrochemical characterization of localized corrosion mechanism of ALD Al2O3-coated copper for microelectronic application

To achieve performance and reliability in microelectronics devices, copper interconnections must be protected from aggressive environment during the manufacturing process and throughout the life of the devices. Atomic Layer Deposition Al2O3 thin films has been used as a compatible layer with key integration process steps, as well as being corrosion-resistant in neutral media. However, electrochemical tests in aggressive environment have revealed that the alumina prematurely failed to protect copper from localized corrosion. In this study, local and global electrochemical techniques have been employed to evaluate the reactivity of copper at multiple scales and to elucidate the underlying corrosion mechanisms.

A study on the thermomechanical response of various die attach metallic materials of power electronics

PurposeIn power electronics, there are various metallic material systems used as die attachments. The complete understanding of the thermomechanical behavior of such interconnections is very important. Therefore, this paper aims to examine the thermomechanical response of four famous die attach materials, including sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds, using nonlinear finite element analysis.Design/methodology/approachDuring the study, the mechanical properties of all die attach systems, including elastic and viscoplasticity parameters, are obtained from literature studies and hence incorporated into the numerical analysis. Subsequently, the bond stress–strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results showed that the silver-tin TLP bonds are more likely to develop higher inelastic strain energy densities, while the sintered silver and copper interconnects would possess higher plastic strains and deformations. Suggesting higher damage to such metallic die attachments. The expensive gold-based solders have developed least inelastic strain energy densities and least plastic strains as well. Thus, they are expected to have improved fatigue performance compared to other bonding configurations.Originality/valueThis paper extensively investigates and compares the mechanical and thermal response of various metallic die attachments. In fact, there are no available research studies that discuss the behavior of such important die attachments of power electronics when exposed to mechanical and thermomechanical loads.

Research on the creep response of lead-free die attachments in power electronics

PurposeThe purpose of this paper is to investigate the thermomechanical response of four well-known lead-free die attach materials: sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds.Design/methodology/approachThis examination is conducted through finite element analysis. The mechanical properties of all die attach systems, including elastic and Anand creep parameters, are obtained from relevant literature and incorporated into the numerical analysis. Consequently, the bond stress-strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results indicate that silver-tin TLP bonds are prone to exhibiting higher inelastic strain energy densities, while sintered silver and copper interconnects tend to possess higher levels of plastic strains and deformations. This suggests a higher susceptibility to damage in these metallic die attachments. On the other hand, the more expensive gold-based solders exhibit lower inelastic strain energy densities and plastic strains, implying an improved fatigue performance compared to other bonding configurations.Originality/valueThe utilization of different metallic material systems as die attachments in power electronics necessitates a comprehensive understanding of their thermomechanical behavior. Therefore, the results of the present paper can be useful in the die attach material selection in power electronics.

Electroplated Copper Additives for Advanced Packaging: A Review.

Acid copper electroplating stands as a core technology in advanced packaging processes, facilitating the realization of metal interconnects, bumps, vias, and substrate wiring between transistors. The deposition quality of copper interconnect materials has a crucial impact on the final performance of chips, directly influencing their yield, reliability, and stability. In this intricate process, additives play a pivotal role in regulating the deposition quality and behavior of metal copper. This mini-review comprehensively summarizes the recent research progress in the field of electroplating copper additives for advanced packaging, both domestically and internationally, delving into the types and mechanisms of various additive molecules, including accelerators, inhibitors, and leveling agents. Through in-depth research on these additives, we gain a profound understanding of their specific roles in the electroplating process and the intricate interaction mechanisms among them, providing theoretical support for optimizing the electroplating process. Furthermore, this mini-review also delves into a thorough analysis of the current issues and challenges facing acid copper electroplating, exploring the key factors that constrain the further development of electroplating copper technology. Based on this analysis, we propose several potential solutions and research directions, offering crucial references for the development and application of electroplating copper additives in advanced packaging. In conclusion, this mini-review aims to provide a comprehensive perspective and profound understanding of the development and application of electroplating copper additives through a review and analysis of recent research progress, ultimately aiming to promote the further advancement of advanced packaging technology.

Effect of Novel pH Regulators on Copper film Chemical Mechanical Polishing for Ruthenium-Based Copper Interconnect under Weak Alkalinity Conditions

For Ruthenium (Ru)-based copper (Cu) interconnects Cu film chemical mechanical polishing (CMP), it is crucial to select appropriate pH regulators in the slurry to ensure the chemical reactions and maintain the stability of the polishing chemical environment. In this study, the effects of inorganic pH regulator KOH, organic pH regulator diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP) on CMP and slurry properties of Cu film were compared. It was found when using AMP as a pH regulator, the Cu/Ru removal rate selectivity (RRS) can reach 598:1, the surface roughness of Cu film decreased to 0.76 nm, and the slurry can remain stable for at least 7 d. The performance order of the three pH regulators is AMP＞KOH＞DEA. Meanwhile, through experimental results and test analysis, it has been confirmed that AMP can also play a multifunctional role as a complexing agent, dispersant, and surfactant. Therefore, AMP can replace KOH as a new pH regulator in weak alkaline slurries. This result plays an important role in guiding the selection of organic pH regulators in the optimization of Cu film CMP slurry.