Chemical Mechanical Planarization of Copper: Role of Oxidants and Inhibitors

Deshpande, Sameer; Kuiry, S. C.; Klimov, Mikhail; Obeng, Yaw S.; Seal, Sudipta

doi:10.1149/1.1806395

Cited by 93 publications

(86 citation statements)

References 31 publications

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“…46 With the increase in the BTA concentration, the N(1s) peak at 399.8 eV becomes more apparent, which is probably attributed to the increase in the intensity of the 316L stainless steel-BTA complex on the surface. 47 The passivation of BTA can be explained as follows. According to the inference in Effect of H 2 O 2 on the polishing performance of 316L stainless steel section, the addition of H 2 O 2 can accelerate the formation of the oxide film, of which the outer layer is mainly composed of iron oxides.…”

Section: Resultsmentioning

confidence: 99%

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Jiang

Yang

2015

ECS J. Solid State Sci. Technol.

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Recently, stainless steel has been widely used as the solar cell substrate. In this paper, chemical mechanical polishing technique was employed to prepare the ultra-smooth 316L stainless steel surface for such application. The effects of solid content, pH, H 2 O 2 and benzotriazole (BTA) on the polishing performance of 316L stainless steel were investigated. The results indicated that, at pH 4.00, with the increase in the H 2 O 2 concentration, the MRR first dramatically increases due to the fact that, with the addition of small amount of H 2 O 2 , a porous outer layer mainly consisting of iron-enriched oxides with relatively low mechanical strength of the bilayer-structure oxide film is rapidly formed on the surface. After reaching the maximum value, the MRR gradually decreases since the outer layer gradually grows compact by the transformation of γ-FeOOH into α-FeOOH and even into α-Fe 2 O 3 . With the addition of BTA, the MRR can be suppressed, which is probably attributed to the formation of BTA passivating film on the top surface. Finally, a two-step polishing method was proposed, by which the ultra-smooth 316L stainless steel surface with the surface roughness R a about 2.0 nm can be achieved within 30 min and it can be subsequently used for thin-film solar cells. Stainless steel plays an important role in the mechanical industry due to the excellent mechanical properties, the high thermostability and the strong corrosion resistance. Recently, various types of stainless steels have been intensively used in precise devices, 1-4 especially been used as the substrate for thin-film solar cells. [5][6][7][8][9][10] In order to achieve satisfactory performance of solar cells, low roughness, low defects as well as excellent flatness of the stainless steel substrate are intensively demanded and even indispensable. It is reported that, by improving the surface roughness of stainless steel substrate from 38 nm to 23 nm, the conversion efficiency of hydrogenated amorphous silicon thin-film solar cells can greatly increase to 5.4%. 10 As is revealed, chemical mechanical polishing (CMP) combines the synergetic effects of chemical corrosion and mechanical abrasion, and can achieve both local and global planarization of the substrate surface. 11-14Hu et al.2 used colloidal silica as the abrasive and investigated the effects of pH and oxidizer on the polishing performance of stainless steel, and it was reported that the combination of oxidizer and strong acidity was the prerequisite for high material removal rate (MRR). However, the microscopic defects of 1-2 μm in size cannot be effectively avoided on the polished surface. Lee et al.10 used electrochemical mechanical polishing technique, which applied an additional anodic potential on the stainless steel substrate besides CMP, to polish the stainless steel surface, and it was reported that the polished surface roughness was reduced from about 38 nm to about 23 nm. However, more detailed polishing performance and the mechanism of chemical reactions during the polishing pr...

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Section: Resultsmentioning

confidence: 99%

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Jiang

Yang

2015

ECS J. Solid State Sci. Technol.

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“…Benzotriazole (C 6 H 5 N 3 , BTAH) has been extensively studied as an inhibitor for the corrosion of copper and many of its alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], for dezincification of brass [17,18] and as additive in the etching [19], electrodeposition [20][21][22] and in the chemical mechanical polishing of copper [23][24][25]. It has also been reported to inhibit the corrosion of iron [26][27][28], cobalt [29], zinc [30], and nickel [28] and to enhance the resistance of tin bronze to oxidation in air [31].…”

Section: Introductionmentioning

confidence: 99%

A quartz crystal microbalance study of the kinetics of interaction of benzotriazole with copper

2007

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The kinetics of interaction of benzotriazole (C 6 H 5 N 3 , BTAH) with the surface of copper in salt water were studied using an electrochemical quartz crystal microbalance and X-ray photoelectron spectroscopy (XPS). Upon injecting BTAH into the electrolyte, three regions appear in the time response of the microbalance. Region I (at short time of few minutes), exhibits rapid linear growth of mass with time, which is attributed to the formation of a protective Cu(I)BTA complex. Region II reveals attachment of BTAH at a slower rate onto the inner Cu(I)BTA complex. Region III is a plateau indicating that the BTAH film attains an equilibrium mass and thickness, which increase with the concentration of BTAH. The intensity of the N1s peak in the XPS spectra increases with the time of immersion, indicating more BTAH on the surface. The results suggest a duplex inhibitor film composed of an inner thin layer of Cu(I)BTA and an outer layer of physically adsorbed BTAH which increases in thickness with time and BTAH concentration. They also offer an explanation for the much documented findings of simultaneous increase of the polarization resistance and decrease of double layer capacity with inhibitor concentration and time of immersion.

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“…Since CMP MRR is dependent on the nanoparticle size and concentration in the slurry, the effects have been investigated by many researchers [26][27][28][29][30][31][32][33][34][35][36]. The reported results are often contradictory and are explained based on the selected ranges of the nanoparticle size and concentration, as well as by their behavior during the CMP process.…”

Section: Effect Of the Slurry Nanoparticle Size And Concentrationmentioning

confidence: 99%

“…In the literature, there are numerous studies on similar topics [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] applied to the copper CMP of integrated circuits. It is worth mentioning that the present study intends to extend to other fields, namely to surfaces coated through selective transfer (the surfaces of the selective layer) in the friction process, considering the slurry pH (important for removal through CMP of the selective layer) [7,[22][23][24][25][26], H 2 O 2 (the most common oxidant) [27][28][29][30][31][32][33], size [21,[28][29][30][31], and concentration [12,21,34] of nanoparticles used in the CMP slurry. Thus, this paper explores the pH effect at a constant H 2 O 2 concentration on the etching and polishing behavior of the selective layer and the influences on size and concentration of nanoparticles during selective layer surface CMP.…”

Section: Introductionmentioning

confidence: 99%

Chemical-Mechanical Impact of Nanoparticles and pH Effect of the Slurry on the CMP of the Selective Layer Surfaces

Ilie

Ipate

2017

Lubricants

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This paper provides a tribochemical study of the selective layer surface by chemical mechanical planarization (CMP). CMP is used to remove excess material obtained in the process of selective transfer. The paper aims at a better understanding of the planarization (polishing) and micromachining. The planarization becomes effective if the material removal rate (MRR) is optimal and the surface defects are minimal. The pH of the slurry plays a very important role in removing the selective layer by CMP, and hydrogen peroxide (H 2 O 2 ) is the most common oxidizer used in CMP slurry. The purpose of this paper is the analysis of the pH effect on the etching rate (ER) and on the behavior of selective layer polishing by a constant concentration of H 2 O 2 and the influence of nanoparticles size and concentration on selective layer surface CMP. The nanoparticle size used is 250 nm. The MRR results through CMP and ER have been shown to be influenced by the presence of oxides on the selective layer surface and have been found to vary with the slurry pH at constant H 2 O 2 concentrations. The CMP slurry plays an important role in the CMP process performance and should be monitored for optimum results and minimal surface defects. The paper analyzes the impact of chemical-mechanical, inter-nanoparticle, and pad-nanoparticle-substrate interactions on CMP performance, taking into account the state of friction at the interface, by measuring the friction force. Selective layer CMP optimization studies were required to control the chemical and mechanical interactions at the interface between the slurry and the selective layer, the slurry chemistry, the properties, and the stability of the suspended abrasive nanoparticles.

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Chemical Mechanical Planarization of Copper: Role of Oxidants and Inhibitors

Cited by 93 publications

References 31 publications

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

A quartz crystal microbalance study of the kinetics of interaction of benzotriazole with copper

Chemical-Mechanical Impact of Nanoparticles and pH Effect of the Slurry on the CMP of the Selective Layer Surfaces

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