Kathleen M. O'Connell

Understanding dissolution behavior of 193nm photoresists in organic solvent developers

Herein, we investigate the dissolution behavior of 193-nm chemically amplified resist in different organic solvents at a mechanistic level. We previously reported the effect of solvent developers on the negative tone development (NTD) process in both dry and immersion lithography, and demonstrated various resist performance parameters such as photospeed, critical dimension uniformity, and dissolution rate contrast are strongly affected by chemical nature of the organic developer. We further pursued the investigation by examining the dependence of resist dissolution behavior on their solubility properties using Hansen Solubility Parameter (HSP). The effects of monomer structure, and resist composition, and the effects of different developer chemistry on dissolution behaviors were evaluated by using laser interferometry and quartz crystal microbalance. We have found that dissolution behaviors of methacrylate based resists are significantly different in different organic solvent developers such as OSDTM-1000 Developer* and n-butyl acetate (nBA), affecting their resist performance. This study reveals that understanding the resist dissolution behavior helps to design robust NTD materials for higher resolution imaging.

High scan speed EBL containing contact hole resists with low defectivity

In the previous paper we discussed the relationship between blob defect count and the receding angle of a resist surface after development with an alkaline developer solution. This paper summarizes additional test results from our continued efforts in developing next generation embedded barrier layer (EBL) materials that render a resist film with even higher receding angle to further facilitate high speed and high acceleration scanning. How to reach a higher receding angle without sacrificing a low post development receding angle is also discussed in this paper. The ability for an EBL material to switch from a high receding angle to a receding angle of lower than 20° upon development is considered a very important attribute of an EBL, which is the key to reduce blob defect count by ensuring good dynamic wetting of a resist surface to DI water during a post development rinsing step. Resist formulations with different receding angles were studied for lithography performance and defectivity under different process conditions with varying wet processes. Both good lithography performance and low defectivity were obtained for contact hole resists including those with a surface receding angle of 78°.

Reflection control for immersion lithography: a single organic antireflectant over high-reflective substrates for double patterning

When patterning critical layers at hyper NA, a multilayer antireflectant system is required in order to control complex reflectivity resulting from various incident angles. Multilayer antireflectants typically consist of an organic antireflectant and inorganic substrates. However, there are still some applications which need a single organic antireflectant over high reflective substrates. A 2P2E application in double patterning is one of them. Even though the pitch for double patterning is relatively loose, the reflectivity control is still challenging in terms of profiles and overall process window. The optical constants and thickness of antireflectants should be well optimized depending on applications. We have investigated several organic antireflectants for a single antireflectant over high reflective substrates. The organic films differ in terms of n, k, thickness to cover both the 1st minimum and the 2nd minimum applications. The overall patterning performance including profiles and process window has been evaluated. ASML 1900i was used to perform lithography. Simulation was performed using ProlithTM software.

Immersion BARC for hyper NA applications II

Reflectivity control through angle is challenging at hyper NA, especially for Logic devices which have various pitches in the same layer. When patterning critical layers, a multilayer antireflectant system is required in order to control complex reflectivity resulting from various incident angles. Multilayer antireflectants typically consist of an organic and inorganic (TiN and SiON) layers. Fewer or thinner layers are desired for etch pattern transfer. However, it would make the reflectivity control through angle more difficult. We have investigated several antireflectants for a simplified multilayer stack. The organic films differ in terms of n, k, thickness and etch rate. The n, k, and thickness span the ranges of 1.60-1.85, 0.15-0.30, and 30-130nm, respectively. The overall patterning performance including profiles, line width roughness (LWR), overlap depth of focus margin (ODOF) and critical dimension uniformity (CDU) has been evaluated. An immersion tool at 1.35NA was used to perform lithography. Simulation was performed using ProlithTM software.