Spin-on hard mask with dual-BARC property for 50-nm devices

Abstract

ArF lithography is in the early stage of mass production and also is going to be further extended to 40nm generation with the aid of immersion lithography. Therefore, it is important to make ArF process production-friendly and extendible for the continuous shrinkage of design rule. Development of ArF process has proceeded with the increase of numerical aperture (NA) and the decrease of resist thickness, which are causing several problems both in mass production and development stage. NA is going to exceed unity in immersion, which necessitates the use of dual bottom antireflective coating (BARC) with increased process complexity and cost. Resist thickness, on the other hand, is expected to further decrease below 100 nm. Therefore, it is inevitable to use additional hard masks, which increases production cost due to chemical vapor deposition (CVD) process. Here we disclose our novel spin-on hard mask system with dual BARC property to overcome both problems aforementioned. Spin-on hard mask composed of two layers of siloxane and carbon materials shows high etch selectivity between thin resist and several substrates. Composition and etch chemistries of two layers are intensively studied to give CVD-comparable step-by-step etch selectivity to transfer various patterns of thin resist including line/space and contact holes to the various substrates. In addition, optical properties of two layers are finely designed from comprehensive optical simulation to be applied to various generation of ArF lithography from dry to immersion process. Such designed optical properties are incorporated to the above two layers of spin-on hard mask. This novel system is under extensive optimization to be applied to various generation of ArF lithography from mass production to the most pioneering semiconductor devices utilizing immersion lithography.