Chemical bonding and interdiffusion in scaled down SiO2∕Si3N4∕SiO2 stacks with top oxide formed by thermal ed copyoxidation

Saraf, Meirav; Edrei, R.; Akhvlediani, R.; Roizin, Yakov; Shima-Edelstein, Ruth; Hoffman, A.

doi:10.1116/1.2209990

Cited by 6 publications

(2 citation statements)

References 29 publications

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“…Also relevant are the observations by several authors that dry and wet (using H 2 O instead of O 2 ) oxidation result in different forms of oxynitride. Saraf et al 22 in a very detailed analysis reported that dry oxidation at 1200 • C results in an order of magnitude higher O 2 incorporation compared with wet oxidation. Indeed, their data indicate that thermal oxidation creates a large concentration of N-O bonds whereas Si-O bonds dominate in the native oxynitride present on a nitride film.…”

Section: Proposed Mechanism For Silicon Nitride and Silicon Dioxide R...mentioning

confidence: 99%

Role of Ce³⁺Ions in Achieving High Silicon Nitride Polish Rates

Alety

Sagi

Babu

2017

ECS J. Solid State Sci. Technol.

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We show that Ce 3+ ions when used as an additive to ceria dispersions enhance plasma-enhanced chemical-vapor-deposited silicon nitride polish or removal rates (RRs). Ceria slurries (0.1 wt% and 140 nm avg. size) containing 2.3 mM Ce(NO 3 ) 3 and no other additive gave nitride RRs of ∼300 nm/min at 4 psi and ∼350 nm/min at 5 psi, both at pH4. The nitride RRs measured in the presence of Ce(NO 3 ) 3 , Ce(CH 3 COO) 3 and KNO 3 suggest that the rate enhancement is solely due to the presence of Ce 3+ ions. We discuss the underlying mechanism causing high silicon nitride RRs in the presence of Ce 3+ ions based on XPS analysis of pre-and post-polished silicon nitride and oxynitride film surfaces, streaming potential data and high oxynitride RRs obtained using the same ceria particle-based slurries as above. It is suggested that the Ce 3+ ions convert the upper layers of the nitride film into an oxynitride that is polished by the abrasives at a high rate. In this process, the conversion of the nitride film seems to be the rate controlling step with the oxidation and polishing occurring in a repetitive manner. © The Author Semiconductor device scaling led to the shrinking of device structures and also created new challenges in the front end of line integration schemes that required several additional new chemical mechanical planarization (CMP) steps. One such new integration scheme in the replacement metal gate (RMG) process is the self-aligned contact (SAC) module where a silicon nitride CMP step is required as shown in Figure 1 (Redrawn from Ref. 1). Since the composition of this silicon nitride film and those used in our experiments is nonstoichiometric, we will refer to them by the generic symbol SiN. In this SAC module, one of the challenges is the misalignment of the contact metal and source/drain, leading to device failure. In order to provide a wider process margin in contact alignment, a SiN cap is deposited on top of the metal gate.1 In the process of depositing this SiN cap, there will always be some SiN overburden, as shown in Fig. 1, which needs to be removed using a highly selective nitride slurry that has a very low oxide removal rate to minimize loss of the underneath oxide. This removal rate selectivity requirement in this SiN cap CMP process is the reverse of that needed in the more conventional shallow trench isolation (STI) CMP and is often referred to as reverse STI selectivity. 2-8Several authors 2-8 investigated reverse STI selectivity CMP processes using ceria and silica based dispersions with various additives. Recently Bae et al.2 achieved highly selective Si 3 N 4 to SiO 2 removal rate (RR) ratio of ∼ 95.0 at pH 1.5 using modified silica abrasives. They modified the surface charge of the silica abrasives toward more negative values (−50 mV) since creating higher negative charge on silica abrasives enables stronger attractive forces between them Si 3 N 4 films and a stronger repulsive force toward silica films in a low pH environment, which can lead to high nitride to oxide removal rate selectiv...

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Section: Proposed Mechanism For Silicon Nitride and Silicon Dioxide R...mentioning

confidence: 99%

Role of Ce³⁺Ions in Achieving High Silicon Nitride Polish Rates

Alety

Sagi

Babu

2017

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…Also, it was found that nitrogen diffusion to Si/SiO 2 interface happens in the course of ONX fabrication including a thermally activated process. [2,3] In the charge trap memory with Oxide-Nitride-Al2O3 structures, in this work, NBTI has been investigated on the basis on nitride traps.…”

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confidence: 99%