Preliminary Study of Polymer Removal in 0.25, 0.3, and 0.5 µm Ruthenium Storage Nodes and 0.11 µm, 10.9:1 High-Aspect-Ratio Trenches by Laser-Induced Etching

Abstract

The demands for new etching technology are increasing because of new materials, such as, ruthenium (Ru), platinum (Pt), and iridium (Ir), that are now being used, and the strict critical dimension (C/D) controls required in today's ultra large scale integrated (ULSI) circuit technology and dynamic random-access memory (DRAM) fabrication lines. Laser etching technology successfully etched organometallic polymers generated after reactive ion etching and ash processing in 0.25, 0.3, and 0.5 µm Ru storage nodes. In this study, the effects of the incident beam profile on the laser-induced etching of the polymers are investigated. Unevenness of the peak energy in the Gaussian beam profile creates unequal etching and heating effects on the polymer removal depending on the irradiating position of the line beam profile on the sample surface. This article discusses for the first time the preliminary results of laser-induced etching with a KrF laser to remove photoresist (PR) and polymer in 0.11 µm deep contact holes with a high-aspect-ratio 10.9:1 trench hole. How deep can the laser etching technology penetrate and strip the PR at a high aspect ratio (A/R) of 10.9:1 and a 0.11 µm hole size? The penetration depth for the PR removal was approximately 1 µm, which is about a 9.1:1 A/R in a 0.11 µm hole with a 1.2-µm-deep trench. Several promising points are discussed on the basis of laser etching in such a high A/R and small 0.11 µm contact hole. Laser-induced etching technology enabled a very uniform penetration depth without any fluctuations, and it also did not show any attack on the edge of the barrier material TiN.