Chemical Mechanical Planarization of Copper and Barrier Layers by Manganese(IV) Oxide Slurry

Hara, Tohru; Kurosu, Toshiaki; Doy, Toshiro

doi:10.1149/1.1413702

Cited by 18 publications

(12 citation statements)

References 6 publications

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“…[1][2][3][4][5][6][7][8][9] However, various defects, such as Cu dishing and oxide erosion, can occur during the CMP process. Cu dishing depth ͑DD͒ is affected by many process parameters, including the Young's modulus of the polishing pad.…”

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confidence: 99%

Nonlinear Dependence of Cu Dishing Depth on the Microstructure of Polishing Pads during Chemical Mechanical Polishing

Kung¹,

Liu²,

Chang³

et al. 2009

J. Electrochem. Soc.

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The relationship between Cu dishing depth ͑DD͒ and Young's modulus of polishing pads during chemical mechanical polishing for various Cu linewidths is investigated. For the Cu width of 150 m, the results show that increasing Young's modulus from 161 to 180 kgf/cm 2 slightly decreased Cu DD; there was a major linear decrease until 195 kgf/cm 2 , and Cu DD was a constant value up to 208 kgf/cm 2 . These three regions are characterized by the threshold, linear, and saturated zones. Scanning electron microscopy results show that the nonlinear behavior is in response to the changes in the ratio of pore areas within the polishing pads. We build a model and define an effective polishing length, L C ‫ء‬ , to predict Cu DD. L C ‫ء‬ is the rotation mode of L C , the static distance between two neighboring pores. The proposed model shows that the three regions are determined by competition between static chemical etching and variable mechanical wearing resulting from the pore area ratio in relation to Young's modulus. The model is useful for understanding the nonlinear behavior between Cu DD and Young's modulus of the pad.Chemical mechanical polishing ͑CMP͒ is widely applied in the planarization of Cu interconnect metallization manufacturing. 1-9 However, various defects, such as Cu dishing and oxide erosion, can occur during the CMP process. Cu dishing depth ͑DD͒ is affected by many process parameters, including the Young's modulus of the polishing pad. 1,2 Metal dishing leads to line resistance deviation, and the resulting surface topography leads to additional problems for the next-level metal-line fabrication. To better understand Cu DD to improve planarization, various models have been established to visualize surface evolution. Many studies assume a direct waferpolishing pad contact, and the concept of the contact mode comes from two objects rubbing against each other during glass polishing. 10-13 Nguyen et al. 10 developed a model for the contact area of the pad and the wafer, the number of contacts, and the size distribution of the contact areas as functions of polishing parameters and pad properties. The magnitude of dishing greatly increased with increasing feature size and the number of contacts. The size distribution of contacts determines the amount of dishing of a metal line. Metal-line dishing also increases with decreasing pad modulus. 12,13 Previous studies on the effect of a pad modulus were limited to Young's modulus regimes larger than 200 kgf/cm 2 and smaller than 160 kgf/cm 2 for low and high magnitude dishing, respectively. Due to the limited range of investigated Young's moduli, the detailed mechanism is still far from being completely understood. In the present study, we investigate the planarization behavior during polishing by extending the range of Young's moduli of polishing pads and Cu linewidths for a complete analysis. A nonlinear dependence was found, which can be divided into three regimes: saturation, linear, and threshold. A model is established to understand the nonlinear behavior and to...

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confidence: 99%

Nonlinear Dependence of Cu Dishing Depth on the Microstructure of Polishing Pads during Chemical Mechanical Polishing

Kung¹,

Liu²,

Chang³

et al. 2009

J. Electrochem. Soc.

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“…When 1 wt% MnO 2 was added to 10 wt% silica, the RRs of SiC were still relatively high at ∼1200 nm h −1 . Since MnO 2 by itself is a good abrasive, oxidizer and was used to polish Cu, SiO 2 , low-K dielectrics films and different types of crystalline SiC films, 22,24,[28][29][30][31] we polished a-SiC wafers with 1 wt% MnO 2 powder alone and found that the RRs were only ∼260 nm h −1 , perhaps due to the reduced abrasive action. These data suggest the possibility of strong interaction between the copper and manganese based additives and the a-SiC surface but also emphasize the need for abrasive action to obtain high RRs.…”

Section: Resultsmentioning

confidence: 99%

Effect of Transition Metal Compounds on Amorphous SiC Removal Rates

Lagudu

Babu

2014

ECS J. Solid State Sci. Technol.

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We show here that transition metal compounds when used as additives to silica dispersions enhance a-SiC removal rates (RRs). Silica slurries containing KMnO 4 gave RRs as high as 2000 nm h −1 at pH 4. Addition of CuSO 4 to this slurry further enhanced the RRs to ∼3500 nm h −1 at pH 6. Furthermore, addition of a low concentration of 250 ppm Brij-35 to this slurry suppressed the RRs of SiO 2 to zero, while retaining the RRs of a-SiC at ∼2700 nm h −1 , a combination of RRs that is appropriate for hard mask polishing. The underlying mechanisms causing the enhancement in the RRs of a-SiC in the presence of transition metal compounds is discussed based on the RR data and XPS analysis of post-polished wafer surfaces. It is shown that a mixed redox system consisting of the oxidation of a-SiC by KMnO 4 enhanced by the catalytic activity of the Cu(II) salt is responsible for the rapid oxidation of a-SiC and the observed enhancement in polish rate with silica based slurries. The adsorption characteristics of Brij-35 on the oxide and carbide surfaces are described based on thermogravimetry data and in achieving the desired polish rate selectivity. Amorphous SiC (a-SiC) thin films, deposited at a low temperature of ∼400• C using a plasma enhanced chemical vapor deposition (PECVD) process, have excellent chemical and temperature resistance and a wide bandgap. These characteristics make them suitable as etch masking layers during advanced semiconductor, solar cell and micro-electro mechanical system (MEMS) fabrication.1-16 Examples of these applications include deep etching of glass or silicon, protection of low-K dielectric films, as a stop layer in STI CMP, etc. 10,12,14 The planar surface necessary to use a-SiC as a hard mask in these applications can be potentially achieved using chemical mechanical planarization (CMP).14 Since, the a-SiC hard mask layers typically protect an underlying dielectric material, generally SiO 2 , the CMP polish process must be selective to it. To the best of our knowledge slurries that can selectively polish SiC over SiO 2 have not been reported.Early work on developing slurries for 6H-SiC CMP showed that Cr 2 O 3 -based slurries increased the removal rates (RRs) compared to the traditional abrasives and oxidizers. 24 reported that slurries containing "soft functionalized particles" coated with several layers of "transition metal catalysts" yielded RRs ranging from 100 nm h −1 to 2500 nm h −1 depending on the concentration of the additives, the abrasives used and the operating conditions. The final surface quality was reported to be very good. In all these cases where high RRs were reported, 22,24 the effect of pressure and other operating conditions, the role of pH, the mechanism of the polish process and the role of various additives that are typically required for evaluating CMP processes were not discussed. More importantly, no slurries that lead to a selective removal of any type of SiC over * Electrochemical Society Active Member.z E-mail: babu@clarkson.edu SiO 2 that is needed for mask ...

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“…Scratch-free polishing is possible by this chemical polishing for the copper conductive layer, as reported elsewhere. 11 The critical pressure, P c , is defined as the pressure at which peeling occurs during polishing, where polishing pressure increased gradually with 50 g/cm 2 step. This pressure was determined practically in the chemical polishing for copper layers deposited on type A and B seed layers.…”

Section: Resultsmentioning

confidence: 99%

Properties of Copper Layers Deposited by Electroplating on an Agglomerated Copper Seed Layer

Hara

Toida

2002

Electrochem. Solid-State Lett.

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This paper describes the properties and adhesion strength of electroplated copper layers deposited onto two different seed layers. In a thin ͑10 nm͒ seed layer, which we term seed layer A, agglomeration occurs across the full thickness of the layer and a stress free or lower stress seed layer is formed with an annealing at 400°C. A highly ͑111͒-oriented copper conductive layer is the result of this electroplating strategy. The adhesion strength is so high ͑40 gf͒ that no peeling occurs during chemical mechanical planarization ͑CMP͒ in this layer. When the layer is electroplated onto a thick ͑100 nm͒ seed layer, which we term seed layer B, agglomeration only occurs at the interface with Ta barrier layer with this annealing. Although a smooth copper layer still remains at the surface, a weakly ͑111͒-orientated copper layer is electroplated. The adhesion strength of this type of copper layer is as low as 10 gf so that peeling can easily occur both during annealing and CMP. Correlation is found between the critical pressure defined by the pressure occurring of the peeling in the copper layers during the CMP with adhesion strength.

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Chemical Mechanical Planarization of Copper and Barrier Layers by Manganese(IV) Oxide Slurry

Cited by 18 publications

References 6 publications

Nonlinear Dependence of Cu Dishing Depth on the Microstructure of Polishing Pads during Chemical Mechanical Polishing

Nonlinear Dependence of Cu Dishing Depth on the Microstructure of Polishing Pads during Chemical Mechanical Polishing

Effect of Transition Metal Compounds on Amorphous SiC Removal Rates

Properties of Copper Layers Deposited by Electroplating on an Agglomerated Copper Seed Layer

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