Distortion mechanism of patterning positions in the soft roller printing process for realizing large-area overlay printing

Abstract

Soft roller printing techniques such as rolling mask soft lithography and offset printing are prominent as high-resolution, high-throughput patterning technologies. The overlay accuracy of soft roller printing becomes critical in large-area fabrications since many factors causing overlay errors tend to be proportional to the patterning area. In this study, the mechanism of overlay distortion was investigated in the soft roller printing process using both lab testing and finite element simulations. The overlay distortion is closely related to the deformation of PDMS in soft roller printing and it is key to investigate how PDMS is deformed under various disturbances from equipment and process. Two kinds of major disturbances, ‘nip motion error’ and ‘roundness error’, are defined and their effect on the overlay distortion is discussed. The methodology to improve overlay accuracy in the soft roller printing process is also presented and verified. For the nip motion error, the compensation method, in which the nip motion error is modeled based on the previous printed position errors and the modeled error is compensated by the alignment stage, are proposed. It is proven that high compressibility of cushioning can help to relieve the position errors caused by roundness errors by reducing the deformation of PDMS. Finally, printing position errors can be reduced to the level of a few micrometers when the overlay distortion mechanisms investigated in this study are well controlled.

Actively compensated precision overlay in a reverse-offset printing system for realizing printed electronics of a large-area and multi-layer structure

“…All patterns through the nip are shifted in MD, CD, and yaw direction by the same amount of MD, CD, and yaw errors, respectively. The effect of the synchronization error between the linear motion and rotary motion of the roller is the same as the case of MD motion error [25,26].…”

“…However, there are inevitably six-DOF motion errors in both motion directions and parasitic directions during the rolling contact motions. For example, the overlay distortion mechanism by the in-plane motion errors of the roller is presented in [26]. The in-plane motion errors cause the nip placement errors and finally result in the same amount of the contact position errors between the roller and the substrate (or cliché) assuming there is no slip between the roller and the substrate (or cliché) during rolling contact.…”

“…The MD motion of the roller gantry and the rotary motion of the roller are controlled and synchronized by the ACS motion controller (SPiiPlusEC). The MD and rotary motion errors of the roller during the roller contact motion are key factors to secure the printing position repeatability of the reverse-offset printing as shown in figure 6 [25,26]. Figure 9 shows the MD motion errors with the left vertical axis and the rotary motion errors with the right vertical axis.…”

“…Next, the effect of roll motion error is investigated using the 3D FE model as shown in figure 1(b). The FE model parameters such as geometries, material properties, contact conditions, and boundary conditions came from [26] and the mesh size and type are changed to fit the 3D model and manage the simulation time as shown in table 1. The cushion, support, and PDMS in the table describe the three material layers composing the rolled PDMS blanket.…”

“…However, the deformation of PDMS on the roller negatively impacts the printing position accuracy. The contact positions between the roller and the substrate (or cliché) are mismatched by the deformation of PDMS, which results in printing position errors of reverse-offset printing [25,26]. There are lots of factors that may cause a contact position mismatch during ink transfer in the rolling contact of reverseoffset printing and it is not easy to remove all of such factors that cause a contact position mismatch.…”