Materials Issues and Characterization of Low-k Dielectric Materials

Abstract

Continuing improvement in device density and performance has significantly affected the dimensions and complexity of the wiring structure for on-chip interconnects. These enhancements have led to a reduction in the wiring pitch and an increase in the number of wiring levels to fulfill demands for density and performance improvements. As device dimensions shrink to less than 0.25 μm, the propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance (RC) coupling become significant. Accordingly the interconnect delay now constitutes a major fraction of the total delay limiting the overall chip performance. Equally important is the processing complexity due to an increase in the number of wiring levels. This inevitably drives cost up by lowering the manufacturing yield due to an increase in defects and processing complexity.To address these problems, new materials for use as metal lines and interlayer dielectrics (ILDs) and alternative architectures have surfaced to replace the current Al(Cu)/SiO2 interconnect technology. These alternative architectures will require the introduction of low-dielectric-constant k materials as the interlayer dielectrics and/or low-resistivity conductors such as copper. The electrical and thermomechanical properties of SiO2 are ideal for ILD applications, and a change to material with different properties has important process-integration implications. To facilitate the choice of an alternative ILD, it is necessary to establish general criterion for evaluating thin-film properties of candidate low-k materials, which can be later correlated with process-integration problems.

Chemical vapor deposition–physical vapor deposition aluminum plug process for dynamic random-access memory applications

“…This is because the resistivity of Al is lower than that of W. The process window of the CVD-PVD Al process to obtain complete via filling and consistent M1C via resistance distribution was wide for various process parameters, such as the CVD Al thickness and PVD Al temperature. 10 Figure 3 shows the M2C via resistance distribution of the Al plug splits and the W plug control. 5 However, a very thin ͑down to 10 nm͒, noncontinuous CVD Al film successfully served as a wetting layer for PVD Al reflow, as shown in Fig.…”

“…However, it is a relatively complex process, and the high cost and low yield of metallization are regarded as disadvantageous for the manufacturing of dynamic random-access memory ͑DRAM͒ devices. [7][8][9] Its relative dielectric constant is typically approximately 3.0, 10 and can be as low as 2.2 by the incorporation of pores. [2][3][4] With this integrated CVD-PVD Al approach, we have successfully integrated the CVD-PVD Al plug process into the process flow of a 0.18 m complementary metal-oxide-semiconductor ͑CMOS͒ device in previous work.…”

Materials containing benzocyclobutene units with low dielectric constant and good thermostability prepared from star‐shaped molecules

“…Polymeric low‐dielectric‐constant (low‐k) materials, possessing the advantage of easy processability, have been widely studied as a potential alternative to SiO 2 . Polymers that are suitable for low‐dielectric media should have low dielectric constant and high thermostability because integrated circuits need to be annealed at a temperature above 400 °C for more than 1 h after wiring . In the past decades, tremendous effort has been made to decrease the dielectric constant and improve the thermal stability of interlayer materials .…”

“…8 Polymers that are suitable for low-dielectric media should have low dielectric constant and high thermostability because integrated circuits need to be annealed at a temperature above 400 C for more than 1 h after wiring. 9 In the past decades, tremendous effort has been made to decrease the dielectric constant and improve the thermal stability of interlayer materials. 10,11 A number of polymeric low-k materials have been discussed, including polyimides, [12][13][14][15][16][17] poly(naphthylene)s, 18 SiLK (product of Dow Chemical), 19,20 and benzocyclobutene resins, [21][22][23] and their performance is shown in Table I.…”

Integration of Low‐ k Dielectric Films in Damascene Processes

“…However, in the same generation another interesting class of materials with low k values exists; the organic (carbon-based) polymers. Unfortunately, chemical bonds with low polarizability, in the latter case C-C bonds, tend to be weaker, limiting thermal stability and stiffness, limiting the thermomechanical properties [14]. Therefore, aromaticity is included in order to obtain a certain extent of processability.…”