AVS 62nd International Symposium & Exhibition
    Electronic Materials and Processing Wednesday Sessions
       Session EM-WeA

Invited Paper EM-WeA3
Innovative Technological Solutions for Low-k Integration Beyond 10 nm

Wednesday, October 21, 2015, 3:00 pm, Room 210E

Session: Interconnects: Methods and Materials for Removing Connectivity Constraints
Presenter: Mikhail Baklanov, IMEC
Correspondent: Click to Email
The general issue of porous low-k materials is degradation of their properties with the increasing porosity. The porous materials are soft, mechanically weak, and do not adhere well to silicon or metal wires. The large pore size also make them more sensitive to plasma damage (because of easy penetration of plasma species into the pores). All these challenges are becoming critical in advanced technology nodes when the distance between the metal wires has reduced to tens nm. This is the reason why the present efforts of researches and engineers are oriented to development and evaluation of new types of low-k materials. The materials need to have good mechanical properties, to have sufficient chemical and plasma resistance and small pore size. At the same time the research efforts are also oriented to development of new technological approaches reducing degradation of low-k materials during the integration. The invited talk will include 2 parts. 1. The first part of presentation includes the results of evaluation of new materials with low dielectric constant that are considered as potential candidates for future generations of nanoelectronic devices. These dielectric materials includes new generations of organosilicate glasses (Periodic Mesoporous Organosilicates (PMO), Zeolites and Metal-Organic Frameworks (MOFs). Fabrication of PMO materials is based on self-assembling chemistry and therefore it allows better control of critical properties of low-k materials. MOFs and Zeolites have very small pore size and unique mechanical properties. These materials have been developed in collaboration with several Universities. Their evaluation at imec includes measurement of their porosity and pore size (ellipsometric porosimetry – a technique patented by author), mechanical properties using Nanoidentation, chemical composition (FTIR, XPS, SIMS and some other techniques). Dielectric constant of these materials are measured my using metal-insulator-semiconductor (MIS) structures with Pt electrode. 2. The second part of the presentation is related to development of innovative technological approaches that are considered as key solutions for successful integration of porous low-k materials. Particularly, detailed analysis of recently patented cryogenic plasma etching of low-k materials will be reported. In this technology, the initial chemistries and reaction products are condensed in pores, makes the material dense and prevent penetration of plasma active into the bulk of low-k materials and reduce the plasma “damage”. The results of evaluation have already been published in several papers. By using this technique the lowest integrated k-value of ultralow-k material has been achieved. Completely different integration scenario is considered for 5 nm technology nodes. The damascene technology can’t work in this case because of plasma damage of low-k and the technology can return back to the subtractive approach with metal patterning. Although some industrial Companies are trying to develop technology of plasma etching of Cu, we are developing an alternative approach with metal patterning by using patterned sacrificial polymers. After metal deposition and planarization by chemical mechanical polishing , the sacrificial polymer is removed by using hydrogen plasma, then the trenches and vias are filled by ultralow-k dielectrics. The deposited low-k films is not exposed to plasma. The first results have been generated, the dielectric constants were achieved close to ones obtained cryogenic etch technology. However, some challenges still remain and they also will be highlighted.