Shin-puu Jeng

Preparation Of Low-Density Xerogels At Ambient Pressure For Low K Dielectrics

Low density silica xerogels have many properties which suggest their use as a low dielectric constant material. Recent process improvements to control capillary pressure and strength by employing aging and pore chemistry modification, such that shrinkage is minimal during ambient pressure drying, have eliminated the need for supercritical drying. Although xerogels offer advantages for intermetal dielectric (IMD) applications because of their low dielectric constant (

Highly porous interlayer dielectric for interconnect capacitance reduction

Hydrogen silsesquioxane (HSQ) is a low density material for intra-metal gapfill, that offers low permittivity for interconnect capacitance reduction. Films with k as low as /spl sim/2.2 preferentially form between tightly-spaced metal leads when cured at low temperature (<400/spl deg/C), and interlayer dielectric properties are stable from 1 MHz to 1 GHz. HSQ simplifies the process integration of low-k materials for high performance interconnect applications by using standard semiconductor spin-on production techniques. Use of porous HSQ as a gapfill dielectric dramatically reduces the capacitive coupling between metal leads, resulting in higher interconnect performance.

Material Characterization Of Methyl Siloxane Sogs

Methyl siloxane spin-on-glass (SOG) is a conventional gap-filling material. In accordance with the requirement of low permittivity, many of major SOG suppliers are developing new types of methyl siloxane SOGs. The most interesting property of these SOGs is their permittivity, which we measured by making stack structures of Al-0.5%Cu / TEOS CVD SiO 2 / SOG / n+ Si. We also studied I-V characteristics, refractive indices, FT-IR spectra, stress, and moisture resistance. All of the SOGs showed small stress and fair moisture resistance. Leakage currents were less than 2.5E-10 A/cm 2 for bias voltages up to 5V. Permittivities ranged from 2.9 to 3.6. We observed a correlation between permittivity and FT-IR spectral features associated with Si-O-Si bonds. Reducing the number density of Si-O-Si bonds may be an effective way to lower the permittivity of this class of SOGs

Process Integration Of Low-Dielectric-Constant Materials

As device geometries and operating voltage continue to scale while functional density increases, it is imperative to reduce the RC time delay. The replacement of Si0 2 as an intermetal dielectric with an insulator of lower dielectric constant is a particularly attractive solution since it provides immediate performance improvement through reduction in capacitance. An embedded polymer integration scheme improves the interconnect performance through line-to-line capacitance reduction by using polymer only between tightly spaced lines. The gapfill polymeric materials do not degrade the electromigration performance of standard multilayered TiN/Al/TiN interconnects. Embedded polymers alleviate many of the integration and reliability problems associated with polymer integration, and can be easily adopted into a standard production process.

Texture‐induced asymmetric reactions in TiN/Al–Cu/TiN

Thermally induced reactions in TiN/Al–Cu/TiN have been investigated. It is observed that the amount of the reactions is different at the two interfaces between Al–Cu and TiN. While there is minimal reaction between Al–Cu and the TiN overlayer, the reaction between Al–Cu and the TiN underlayer increases the sheet resistance of Al–Cu by as much as 15%. It is further shown that the asymmetric reactions are most likely caused by the different degree of (111) texture of TiN grown on amorphous SiO2 and textured, polycrystalline Al–Cu.

Polymers for high performance interconnects

It is well-known that capacitance in the metallization is becoming too great to allow the continued use of SiO/sub 2/ as the intermetal dielectric below about the 0.25 /spl mu/m technology node. One of many possible replacements for SiO/sub 2/ are organic polymers. Organic polymers are not drop-in replacements, however, and their successful integration into functional circuits requires new fabrication procedures and integration schemes. The embedded dielectric scheme offers a sound evolutionally path for their successful integration into a subtractive etch, aluminum-based integrated circuit. The embedded dielectric scheme effectively lowers total capacitance and the line-line/total capacitance ratio while minimally changing the rest of the metallization fabrication processes including via formation. Vapor deposited polymers which are conformably deposited like Parylene-n are more easily integrated into the embedded dielectric scheme than nonconformal spin-on dielectric films. Parylene-n copolymers with dielectric permittivities as low as 2.3 also are excellent candidate materials for use in the embedded dielectric scheme and they also have equivalent thermal stability as the homopolymer. New copolymers with comonomers of different functionality should improve both the adhesion and thermal stability of the intermetal dielectric.