Toshiaki Motonaga

Evaluation of dry etching and defect repair of EUVL mask absorber layer

EUVL mask process of absorber layer, buffer layer dry etching and defect repair were evaluated. TaGeN and Cr were selected for absorber layer and buffer layer, respectively. These absorber layer and buffer layer were coated on 6025 Qz substrate. Two dry etching processes were evaluated for absorber layer etching. One is CF4 plasma process and the other is Cl2 plasma process. Etch bias uniformity, selectivity, cross section profile and resist damage were evaluated for each process. Disadvantage of CF4 plasma process is low resist selectivity and Cl2 plasma process is low Cr selectivity. CF4 plasma process caused small absorber layer damage on isolate line and Cl2 plasma process caused Cr buffer layer damage. To minimize these damages overetch time was evaluated. Buffer layer process was also evaluated. Buffer layer process causes capping layer damage. Therefore, etching time was optimized. FIB-GAE and AFM machining were applied for absorber layer repair test. XeF2 gas was used for FIB-GAE. Good selectivity between absorber layer and buffer layer was obtained using XeF2 gas. However, XeF2 gas causes side etching of TaGeN layer. AFM machining repair technique was demonstrated for TaGeN layer repair.

Study of mask process development for EUVL

EUVL mask process of absorber layer dry etching and defect repair were evaluated. TaGeN and Cr were selected for absorber layer and buffer layer, respectively. These absorber layer and buffer layer were coated on 6025 Qz substrate. Two dry etching processes were evaluated for absorber layer etching. One is CF4 gas process and the other is Cl2 gas process. CD uniformity, selectivity, cross section profile and resist damage were evaluated for each process. FIB-GAE and AFM machining were applied for absorber layer repair test. XeF2 gas was used for FIB-GAE. Good selectivity between absorber layer and buffer layer was obtained using XeF2 gas. However, XeF2 gas causes side etching of TaGeN layer. AFM machining repair technique was demonstrated for TaGeN layer repair.

Feasibility study of detectivity and printability for TaSiOx-HTPSM

HT-PSMs (Half Tone Phase Shifting Masks) are well known as one of the key technologies to obtain high resolution and expand process window of lithography. And furthermore, high transmission HT-PSMs are expected to show better DOF and MEEF than conventional transmission, such as 6%, HT-PSM. We have already developed and reported TaSiOx shifter as a high transmission HT material for ArF lithography. And also we have reported its process performance such as good phase controllability, vertical side-wall angle, no damage on quartz surface during shifter dry etching and good CD uniformity. The key point to obtain these performances is the characteristics of etching stop function of its bi-layered structure. This bi-layered structure also enabled transmission at the inspection wavelength to keep enough low to inspect by current inspection systems. In this report, in order to confirm the feasibility of mass-manufacturing of the TaSiOx high transmission HT-PSM, we fabricated programmed defect test mask and performed following experiments. Defect detectability was evaluated by KLA-Tencor SLF27 and compared to printability results that were confirmed by ZEISS MSM193. We will also show some preliminarily results of repairing tests on this TaSiOx material.

Development of bilayered TaSiOx-HTPSM: II

TaSiOx shifter has been developed for HT-PSM for ArF and F2 laser lithography. Adopting bilayered structure and embedding an etch-stop function into the transmittance control layer enable us to fabricate a TaSiOx-HT without quartz damage and to control the phase precisely. And less impact of TaSiOx shifter etching to CD was confirmed. It was confirmed this TaSiOx-HT was inspected by conventional inspection system without any problem.