Photoresist Poisoning Research Articles

0.13μm Cu/Low-k 공정 Setup과 수율 향상에 관한 연구

In this study, the inter-metal dielectric material of FSG was changed by low-k material in <TEX>$0.13{\mu}m$</TEX> foundry-compatible technology (FCT) device process based on fluorinated silicate glass (FSG). Black diamond (BD) was used as a low-k material with a dielectric constant of 2.95 for optimization and yield-improvement of the low-k based device process. For yield-improvement in low-k based device process, some problems such as photoresist (PR) poisoning, damage of low-k in etch/ash/cleaning process, and chemical mechanical planarization (CMP) delamination must be solved. The PR poisoning was not observed in BD based device. The pressure in CMP process decreased to 2.8 psi to remove the CMP delamination for Cu-CMP and USG-CMP. <TEX>$H_2O$</TEX> ashing process was selected instead of <TEX>$O_2$</TEX> ashing process due to the lowest condition of low-k damage. NE14 cleaning after ashing process lot the removal of organic residues in vias and trenches was employed for wet process instead of dilute HF (DHF) process. The similar-state of SRAM yield was obtained in Cu/low-k process compared with the conventional <TEX>$0.13{\mu}m$</TEX> FCT device by the optimization of these process conditions.

Analysis of surface contamination on organosilicate low k dielectric materials

It has been widely acknowledged that copper and low k dielectric materials are required in order to reduce RC delay and achieve high-speed operations in VLSI technology. Introduction of copper resulted in the adoption of damascene processing and via-first dual damascene architecture is one of the most popular integration schemes. However, photoresist poisoning is a major challenge and surface contamination of the via side-wall is considered to be the root cause. Wet cleaning has been found to be one of the processes which can lead to wafer surface contamination. In this paper, thermal desorption GC–MS and ToF-SIMS are used to analyze the surfaces of an organosilicate low k material before and after wet cleaning. It has been found that cleaning of the low k wafer with the wet chemicals used in post-etch polymer stripping process and storage of cleaned wafers in a polymer wafer box will lead to amine contamination on the low k surface, probably via airborne molecular contamination. The amount of amine contamination depends on the wet chemicals used, wafer patterning and the wafer storage conditions. The effect of amine contamination on photoresist poisoning is also discussed.

Analysis of amine contamination on silicon oxide surfaces using ToF-SIMS

Contamination detection and control play a critical role in achieving the semiconductor industry’s roadmap. Compared to metal and particle contamination, knowledge on organic contamination and its detrimental effects is still limited. As the devices are continuously scaled down, organic contamination is increasingly become a major yield-affecting factor. Previous studies of organic contamination on silicon oxide surfaces have focused on total carbon contamination and its effects on gate-oxide integrity. During wafer fabrication process, there are many possibilities for organic contamination. Wet cleaning-induced organic contamination is one of them. In this paper, amine contamination on silicon dioxide surfaces caused by wet cleaning is investigated using thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). A semi-quantitative method is adopted to evaluate amine contamination on silicon oxide surfaces. The amount of amine contamination on the oxide surfaces depends on the wet cleaning process and wafer storage conditions. The effect of amine contamination on the photoresist poisoning is also discussed.

Dual Damascene Interconnect Technology for 130-nm-node Complementary Metal–Oxide–Semiconductor Devices Using Ladder-Oxide Film

A 0.34-µm-pitch Cu dual damascene interconnect technology using a low-k ladder-oxide film (k=2.9) is developed for 130-nm-node complementary metal oxide semiconductor (CMOS) devices. Photoresist poisoning was improved by adopting the ladder-oxide film with annealing before the photolithography step. The fence structures around via openings caused poor Cu gap filling. The problem was solved by controlling the filling height of a bottom anti-reflective coating and by eliminating the photoresist poisoning. Furthermore, no degradation of the ladder-oxide film upon photoresist stripping was observed. It was demonstrated that these technologies could be applied to a product-level application-specific integrated circuit chip with a seven-level Cu interconnect.

Inorganic Si-O-C Antireflection Coating at 193 nm for Cu Dual Damascene Process

Silicon oxycarbide (SiOC) films have been investigated as nitrogen (or amine)-free dielectric antireflection layer for a dual damascene structure at 193 nm. Films were deposited by plasma enhanced chemical vapor deposition using trimethylsilane and oxygen. As the oxygen flow rate increased, both the refractive index and extinction coefficient decreased. It was found that reflectance was less than 10% for optimum SiOC, which is comparable to silicon oxynitride. Oxygen plasma treatment converted the top surface of SiOC to silicon oxide. The thickness of the oxide layer increased with the treatment time, however it saturated around 10 nm with treatment times above 90 s. The oxide layer was found to act as a passivation layer stabilizing the SiOC film. It showed reflectance of less than 5% and was successfully utilized as the antireflection layer for a dual damascene structure with no photoresist poisoning. © 2002 The Electrochemical Society. All rights reserved.

Challenge of ashing and cleaning on SiOC-H dielectric: characterization and main issues

During process development of post etch cleaning for dual damascene copper/SiOC-H structures, two different kinds of new problems were faced. While a good efficiency is obviously still needed, attention must also be given to dielectric modification and photoresist poisoning which can be induced by the cleaning processes. This study examines different ways of characterization of these phenomenon.