Prediction of porous dielectric line wiggling phenomenon with metallic hard mask: From simulation to experiment

Ducoté, J.; Possémé, N.; David, T.; Darnon, Maxime; Chevolleau, T.; Guillermet, M.

doi:10.1063/1.4882080

Cited by 13 publications

(20 citation statements)

References 5 publications

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“…36 The residual compressive stress in the fiber-textured TiN film was about 600 MPa and it was enough low to suppress the wiggling phenomenon. 41 The ratio of Ti and N in TiN film was almost 1:1 and TiN contained O with the concentration of 8.0 at.%. The resist pattern for metal lines was formed by the photolithography process.…”

Section: Resultsmentioning

confidence: 99%

High-Performance Extremely Low-k Film Integration Technology with Metal Hard Mask Process for Cu Interconnects

Torazawa

Matsumoto

Harada

et al. 2016

ECS J. Solid State Sci. Technol.

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High performance copper interconnects using extremely low-k film for the interlayer dielectric with the metal hard mask process and the interfacial surface oxygen treatment between extremely low-k film and liner layer was demonstrated. To suppress the process damage of interlayer dielectric and enlarge the space between vias and lines with a wide margin of lithography process, the robust extremely low-k film with the metal hard mask self-aligned via process was developed. The ultimate low capacitance wiring was achieved with the metal hard mask process, and the high reliability performance of time dependent dielectric breakdown between Cu lines with vias was accomplished by controlling the etching selectivity of the metal hard mask and the interlayer dielectrics. The adhesion strength between extremely low-k film and silicon carbide based liner layer was enhanced by controlling the composition of oxygen and carbon at the interface, resulting in the strengthening of the tolerance against chip packaging and thus the highly reliable chip packaging. This metal hard mask self-aligned via process with extremely low-k film and the interfacial surface oxygen treatment was demonstrated to be high performance, and therefore it offers a promising technology for Cu interconnects. Becoming the wiring pitches smaller as well as reducing the kvalue of dielectric materials are continuously required to achieve the high performance copper (Cu) interconnects which have higher speed, lower power and higher density. Thus, several kinds of lower k-value dielectric materials (k < 2.5) have been studied.1-12 However, they have posed many critical issues in the integration such as the degradation of film properties due to the post-process damages [13][14][15] and the weak tolerance against chip packaging due to the fragility of dielectric films and the weak adhesion strength between lower k-value dielectric materials and the underlying liner layer. In addition, shrinking both the size of via and the misalignment margin has essentially become difficult due to the technical limit of the lithography process. Hence, the degradation of reliability performance such as time dependent dielectric breakdown (TDDB) lifetime between Cu lines with vias is one of the most critical issues. Therefore, the self-aligned via process has been reported, [16][17][18][19] and the metal hard mask (MHM) process has been studied 20-32 instead of the conventional resist mask process to suppress the damage of interlayer dielectrics by the ashing process with oxygen (O 2 ) plasma. [33][34][35] We have studied the MHM process using the low stress TiN mask which had a fiber-textured structure for the perfect Cu filling and it has been demonstrated to be high performance. 36 However, the reports on the integration of lower k-value dielectric materials (k < 2.5) with the MHM self-aligned via process have been limited, and the complete process including reliability performance in chip packaging has not been reported.In this paper, high performance Cu interconnects using...

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Section: Resultsmentioning

confidence: 99%

High-Performance Extremely Low-k Film Integration Technology with Metal Hard Mask Process for Cu Interconnects

Torazawa

Matsumoto

Harada

et al. 2016

ECS J. Solid State Sci. Technol.

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“…16 The trench walls areas exhibited buckling and were the focus of study. Etching depth (wall-height) is one of the main parameters that determines buckling: 13,15,16 Sample S2 (Figs. 1(c) and 1(e)) has a width similar to sample S3 (Figs.…”

Section: Materials and Microscopymentioning

confidence: 99%

“…13,15,16 Deterministic buckling models inevitably predict the formation of perfectly periodic deflections; however, measured buckling deflections are clearly pseudo-periodic, exhibiting both phase decorrelation and amplitude fluctuations (Figs. 1(b)–1(d)).…”

Section: Introductionmentioning

confidence: 99%

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Stochastic behavior of nanoscale dielectric wall buckling

Friedman

Levin

Cook

2016

Journal of Applied Physics

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The random buckling patterns of nanoscale dielectric walls are analyzed using a nonlinear multi-scale stochastic method that combines experimental measurements with simulations. The dielectric walls, approximately 200 nm tall and 20 nm wide, consist of compliant, low dielectric constant (low-k) fins capped with stiff, compressively stressed TiN lines that provide the driving force for buckling. The deflections of the buckled lines exhibit sinusoidal pseudoperiodicity with amplitude fluctuation and phase decorrelation arising from stochastic variations in wall geometry, properties, and stress state at length scales shorter than the characteristic deflection wavelength of about 1000 nm. The buckling patterns are analyzed and modeled at two length scales: a longer scale (up to 5000 nm) that treats randomness as a longer-scale measurable quantity, and a shorter-scale (down to 20 nm) that treats buckling as a deterministic phenomenon. Statistical simulation is used to join the two length scales. Through this approach, the buckling model is validated and material properties and stress states are inferred. In particular, the stress state of TiN lines in three different systems is determined, along with the elastic moduli of low-k fins and the amplitudes of the small-scale random fluctuations in wall properties—all in the as-processed state. The important case of stochastic effects giving rise to buckling in a deterministically sub-critical buckling state is demonstrated. The nonlinear multiscale stochastic analysis provides guidance for design of low-k structures with acceptable buckling behavior and serves as a template for how randomness that is common to nanoscale phenomena might be measured and analyzed in other contexts.

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“…One of the problems is that the trench deformation after the etching process, which is known as the wiggling phenomenon. 32 This is due to the stress relaxation of TiN film after the trench formation with the etching process, and it results in the buckled structure. Therefore, the approaches to reduce the residual stress in TiN film used as a hard mask have been also studied.…”

mentioning

confidence: 99%

High-Performance Metal Hard Mask Process Using Fiber-Textured TiN Film for Cu Interconnects

Torazawa

Harada

Konishi

et al. 2016

ECS J. Solid State Sci. Technol.

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One of the most challenging issues in the metal hard mask process for copper interconnects is controlling the residual stress in TiN mask. The relationship between the residual stress and the feature size of the trench was investigated using a mechanical simulation. It was found that the trench deformation at a specific pattern due to the residual compressive stress in TiN film resulted in void formation in Cu. To overcome this problem, the correlation between the residual stress and the film properties of TiN was investigated and a potential TiN mask in the metal hard mask process was studied. The residual stress in TiN film and the etching performance were correlated with the composition and the crystal structure of TiN. The grain growth was suppressed by reducing the energy of sputtered atoms during the deposition of TiN, resulting in low residual stress in TiN film with keeping the etching performance for TiN. By applying low stress TiN mask which had a fiber-textured structure, the trench deformation at a specific pattern could be suppressed and thus Cu filling was perfectly achieved. The metal hard mask process using TiN film which had a fiber-textured structure was demonstrated to be high performance. As the wiring pitches in copper (Cu) interconnect continue to become smaller, resistive-capacitive (RC) delay due to the increase in the capacitance between Cu lines becomes a critical problem. Therefore, the low k-value dielectric materials have been studied to reduce the capacitance between Cu lines.1-8 However, the low-k materials are known to be easily damaged by the post-processes such as the resist ashing process with oxygen (O 2 ) plasma 9-11 because of their low mechanical strength, and it results in k-value increasing.To suppress the damage of interlayer dielectric by the ashing process during the removal of the trench resist, the metal hard mask (MHM) process has been studied instead of the conventional resist mask process.12-24 As a hard mask in the MHM process, Titanium nitride (TiN) has been investigated. [20][21][22][23][24][25][26][27][28][29][30][31] This is because the alignment pattern for photolithography can be easily recognized through TiN film compared to other metal films such as Tantalum nitride (TaN) film. However, the serious problems occurred in the MHM process due to high residual stress in TiN mask. One of the problems is that the trench deformation after the etching process, which is known as the wiggling phenomenon.32 This is due to the stress relaxation of TiN film after the trench formation with the etching process, and it results in the buckled structure. Therefore, the approaches to reduce the residual stress in TiN film used as a hard mask have been also studied. One approach to reduce the residual stress is to reduce the thickness of TiN mask. However, thinner TiN mask tends to result in worse property of a hard mask in the self-aligned via process, and the shrink of the pitches between via and trench occurs. It results in degrading the device yield or the reliability per...

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Prediction of porous dielectric line wiggling phenomenon with metallic hard mask: From simulation to experiment

Abstract: Skeletal silica characterization in porous-silica low-dielectric-constant films by infrared spectroscopic ellipsometry

Cited by 13 publications

References 5 publications

High-Performance Extremely Low-k Film Integration Technology with Metal Hard Mask Process for Cu Interconnects

High-Performance Extremely Low-k Film Integration Technology with Metal Hard Mask Process for Cu Interconnects

Stochastic behavior of nanoscale dielectric wall buckling

High-Performance Metal Hard Mask Process Using Fiber-Textured TiN Film for Cu Interconnects

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