Role of Guanidine Carbonate and Crystal Orientation on Chemical Mechanical Polishing of Ruthenium Films

Amanapu, H. P.; Sagi, K. V.; Teugels, Lieve; Babu, S. V.

doi:10.1149/2.018311jss

Cited by 47 publications

(52 citation statements)

References 57 publications

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“…As mentioned by Amanapu et al, 15 Ru oxides/hydroxides likely form complexes with guanidinium ions in the presence of GC and KMnO 4 at pH 10. These complexes are then polished away by silica abrasives at a down pressure of only 2 psi.…”

Section: 25mentioning

confidence: 70%

Potassium Permanganate-Based Slurry to Reduce the Galvanic Corrosion of the Cu/Ru/TiN Barrier Liner Stack during CMP in the BEOL Interconnects

Sagi

Amanapu

Alety

et al. 2016

ECS J. Solid State Sci. Technol.

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Chemical mechanical polishing (CMP) behavior of Cu/Ru/TiN barrier liner stack was investigated with a slurry comprising of silica abrasives, potassium permanganate (KMnO 4 ) , guanidine carbonate (GC) and benzotriazole (BTA) in the alkaline region. The corrosion and polishing behavior of the Cu, Ru and TiN films in the solution consisting of the above additives were characterized by open circuit potential and potentiodynamic measurements, polishing rates, dissolution rates and contact angle measurements. A slurry comprising of 10 mM KMnO 4 , 1 wt% GC and 5 wt% Silica at pH 10 has shown adequate polish rates as well as low individual film corrosion. However, 1 mM BTA was needed to maintain the E CORR of both the Cu/Ru and Ru/TiN couples at <20 mV essential to inhibit any galvanic corrosion while still maintaining low corrosion rates for Cu, Ru and TiN films. The removal rate ratio of Ru:Cu with the optimized slurry was ∼0.8, minimizing the possibility of dishing. As the scaling of trenches and vias continue, making high volume manufacturing of 14 nm devices feasible, deposition of defect free Cu seed layer upon the TaN/Ta barrier liner 1,2 used in earlier generation Cu interconnects has become a challenge. At the reduced trench widths of ∼50 nm or less associated with these devices, it is not possible to deposit a conformal Cu seed layer without voids.3-6 Also, as the TaN/Ta barrier liner is scaled to ∼5 nm or less in thickness, its increased electrical resistance causes the resistance-capacitance delay to increase. Hence, the advantages of replacing it with several other barrier and barrier liner candidate materials and have been investigated by various authors.7-9 These include Ru, Co and Mn and their alloys.Among these, Ru has good barrier properties with a high melting point of 2310• C. 7 Due to its low resistivity (∼7 μ cm) and excellent wettability characteristics with Cu, direct electroplating of Cu is possible eliminating the need for a seed layer.7 However, it was found that atomic layer deposited (ALD) Ru alone is not a good diffusion barrier due to its columnar growth structure that provides diffusion paths for Cu at the grain boundaries 10,11 and poor adherence to underlying dielectric.12 Hence, it was proposed that a thin TaN barrier layer (∼2-3 nm) be first deposited followed by a ∼1-2 nm thick Ru liner, alleviating the need for a Cu seed layer. 13,14 However, the higher resistivity of TaN (∼200 μ cm) is still a concern.Recently, Amanapu et al. 15 showed that Ru films deposited on TiN, another commonly used barrier layer 16,17 with a lower resistivity of ∼130 μ cm, have higher removal rates (RRs) compared to those deposited on TaN due to the difference in the crystalline orientation of the Ru films deposited on these two materials. Hence, a thin Ru liner (∼2 nm) over a thin TiN barrier layer (∼2 nm), both deposited by ALD, has been proposed as a promising barrier liner for future Cu interconnects.In these structures, since Ru is in contact with both TiN and Cu (Figure 1), there is a possibility of g...

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Section: 25mentioning

confidence: 70%

Potassium Permanganate-Based Slurry to Reduce the Galvanic Corrosion of the Cu/Ru/TiN Barrier Liner Stack during CMP in the BEOL Interconnects

Sagi

Amanapu

Alety

et al. 2016

ECS J. Solid State Sci. Technol.

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“…30 However, Amanapu et al 15 did not investigate the possibility of galvanic corrosion at the Ru/Cu bimetallic interface as well as maintaining an adequate removal rate selectivity of Ru to Cu. In this paper, we describe the results of the studies of the corrosion behaviors of Ru and Cu, using open circuit potential (E OC ) measurements and potentiodynamic polarization experiments, in H 2 O 2 and GC-based solutions at pH 9, a value chosen to avoid the formation of toxic RuO 4.…”

Section: -29mentioning

confidence: 99%

“…13,14 Of these, Ru/TiN structures were chosen for the analysis here since Amanapu et al 15 have shown that these films are polished faster compared to those on TaN. They attributed this to the difference in the crystalline orientation of the Ru films deposited on TiN and TaN layers.…”

mentioning

confidence: 99%

“…13,14 Therefore, a thin (∼1 nm) TaN or TiN layer is deposited between Ru and the dielectric interface which helps in both negating the columnar growth of Ru and improving the adherence between Ru and the dielectric. 13,14 Of these, Ru/TiN structures were chosen for the analysis here since Amanapu et al 15 have shown that these films are polished faster compared to those on TaN. They attributed this to the difference in the crystalline orientation of the Ru films deposited on TiN and TaN layers.…”

mentioning

confidence: 99%

“…[16][17][18] Peethala et al, 19 Turk et al, 20 and several others [21][22][23][24][25] have previously investigated the CMP of Ru and Cu films as well as the galvanic corrosion behavior of the Ru/Cu couple in the presence of potassium periodate, sodium percarbonate and other oxidizers. Recently, Amanapu et al 15 [26][27][28][29] Thus, Ru oxides and hydroxides, but not Ru, in the presence of GC are likely to form complexes through interaction of -electrons on the nitrogen atoms of the guanidinium ions. The binding between these highly electronegative nitrogen atoms and Ru in these complexes can partially polarize the underlying Ru-Ru bonds and weaken them sufficiently to cause rupture during polishing and lead to an increase in the polish rate.…”

mentioning

confidence: 99%

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Investigation of Guanidine Carbonate-Based Slurries for Chemical Mechanical Polishing of Ru/TiN Barrier Films with Minimal Corrosion

Sagi

Amanapu

Teugels

et al. 2014

ECS J. Solid State Sci. Technol.

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This work describes the response of Ru/TiN barrier films to solutions of H 2 O 2, guanidine carbonate (GC) and other additives in terms of open circuit potential measurements and potentiodynamic polarization data. It was found that an aqueous solution containing 1 wt% H 2 O 2 , 0.25 wt% GC and 5 mM BTA is effective in maintaining a low corrosion potential gap of Ru and Cu at ∼15 mV at pH 9. The slurry prepared by adding 5 wt% silica to this mixture yields a Ru removal rate (RR) of 10 nm/min and a Cu RR of 12 nm/min at 2 psi polishing pressure. The effect of carbonate and guanidinium ions as well as BTA on the corrosion behavior of Ru and Cu is discussed. Dodecyl-benzene-sulfonic acid (DBSA) was also found to be an effective corrosion inhibitor of Ru in the presence of H 2 O 2 and GC based solutions at pH 9 with a good post-polished surface finish but reduced the Ru RRs to ∼ 2 nm/min. As the scaling of interconnect structures continues beyond the 22 nm technology node, the width of copper lines continues to diminish. At such lower line widths, the effect of electron scattering on conductivity increases resulting in higher resistivity and reduced current carrying capacity. One way of mitigating this effect is to reduce the barrier liner thickness to less than ∼3 nm to accommodate a thicker copper line within a given trench. In such situations, the Ta/TaN bilayer, commonly used as barrier liner in the earlier copper interconnects, 1-4 faces several challenges. These include an inability to conformally deposit a thin barrier film in the high aspect ratio trenches which inevitably leads to void formation in the subsequently deposited copper seed layer. To surmount such challenges, Ruthenium (Ru) and several of its alloys have been proposed as alternative barrier liners.5-10 These have the added advantage of direct electroplating of Cu, eliminating the need for a Cu seed layer.However, Ru is not an ideal barrier as it forms columnar structures and, hence, provides diffusion paths for Cu at the grain boundaries 11,12 and also has poor adherence to the underlying dielectrics which may result in the peeling of these films during polishing.13,14 Therefore, a thin (∼1 nm) TaN or TiN layer is deposited between Ru and the dielectric interface which helps in both negating the columnar growth of Ru and improving the adherence between Ru and the dielectric. 13,14 Of these, Ru/TiN structures were chosen for the analysis here since Amanapu et al. 15 have shown that these films are polished faster compared to those on TaN. They attributed this to the difference in the crystalline orientation of the Ru films deposited on TiN and TaN layers.It is very difficult to obtain adequate removal rates (RR) of Ru during planarization since it is a noble and hard material, making it a challenge to achieve the desired RR selectivity to Cu at the barrier interface. Moreover, Ru is more cathodic to Cu since its standard reduction potential (0.21 V vs. SCE) is greater than that of Cu (0.1 V vs. SCE). Hence, there is a high possibility of Cu corro...

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High‐Performance Quasi‐Solid‐State Thermogalvanic Cells with Metallized Fibril‐Based Textile Electrodes and Structure‐Breaking Salts

Choi,

Mo,

Jung

et al. 2024

Advanced Energy Materials

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Thermogalvanic cells (TGCs) convert heat into electricity through thermoelectrochemical reactions of redox couples, generating a millivolt‐scale Seebeck coefficient. However, TGCs based on liquid electrolytes are prone to leakage, whereas quasi‐solid‐state TGCs (QTCs) using gel‐based electrolytes typically have low power outputs due to slow ion diffusion and limited reaction rates. Herein, we present novel strategies for developing high‐performance all‐flexible QTCs using both metallized fibril‐based textile electrodes with extremely large surface area, (specifically Ni textiles), and structure‐breaking salts for hydrogel electrolytes. The electrodes are oxidized to create Ni and Ni oxide heterostructures, forming numerous O vacancy defects that enhance redox reactions. Meanwhile, the structure‐breaking salts facilitate redox reactions and improve ion diffusion by disrupting water structures in the hydrogel electrolyte. These advancements significantly enhance the performance of the QTCs without the need for precious‐metal electrodes, achieving a remarkable maximum power density of 4.05 mW m−2 K−2 and a record‐high effective cell conductivity of 17.3 S m−1, compared to previously reported QTCs. Finally, the proposed QTCs can generate a stable open‐circuit voltage and output power for wearable applications owing to the flexibility of the electrodes and electrolyte, achieving successful electronic device operation using body heat from the forearm (ΔT ≈ 2 K).

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Role of Guanidine Carbonate and Crystal Orientation on Chemical Mechanical Polishing of Ruthenium Films

Cited by 47 publications

References 57 publications

Potassium Permanganate-Based Slurry to Reduce the Galvanic Corrosion of the Cu/Ru/TiN Barrier Liner Stack during CMP in the BEOL Interconnects

Potassium Permanganate-Based Slurry to Reduce the Galvanic Corrosion of the Cu/Ru/TiN Barrier Liner Stack during CMP in the BEOL Interconnects

Investigation of Guanidine Carbonate-Based Slurries for Chemical Mechanical Polishing of Ru/TiN Barrier Films with Minimal Corrosion

High‐Performance Quasi‐Solid‐State Thermogalvanic Cells with Metallized Fibril‐Based Textile Electrodes and Structure‐Breaking Salts

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