Optical Proximity Correction Patterns Research Articles

Investigation of the layout and optical proximity correction effects to control the trench etching process on 4H-SiC

Although trench gate and super-junction technology have micro-trench problems when applied to the SiC process due to the material characteristics. In this paper, area effects are analyzed from the test element group with various patterns and optical proximity correction (OPC) methods are proposed and analyzed to reduce micro-trenches in the SiC trench etching process. First, the loading effects were analyzed from pattern samples with various trench widths (Wt). From experiments, the area must limited under a proper size for a uniform etching profile and reduced micro-trenches because a wider area accelerates the etch rate. Second, the area effects were more severely unbalanced at corner patterns because the corner pattern necessarily has an in-corner and out-corner that have different etching areas to each other. We can balance areas using OPC patterns to overcome this. Experiments with OPC represented improved micro-trench profile from when comparing differences of trench depth (Δdt) at out corner and in corner. As a result, the area effects can be used to improve the trench profile with optimized etching process conditions. Therefore, the trench gate and super-junction pillar of the SiC power MOSFET can have an improved uniform profile without micro-trenches using proper design and OPC.

Fast pixel-based optical proximity correction based on nonparametric kernel regression

Optical proximity correction (OPC) is a resolution enhancement technique extensively used in the semiconductor industry to improve the resolution and pattern fidelity of optical lithography. In pixel-based OPC (PBOPC), the layout is divided into small pixels, which are then iteratively modified until the simulated print image on the wafer matches the desired pattern. However, the increasing complexity and size of modern integrated circuits make PBOPC techniques quite computationally intensive. This paper focuses on developing a practical and efficient PBOPC algorithm based on a nonparametric kernel regression, a well-known technique in machine learning. Specifically, we estimate the OPC patterns based on the geometric characteristics of the original layout corresponding to the same region and a series of training examples. Experimental results on metal layers show that our proposed approach significantly improves the speed of a current professional PBOPC software by a factor of 2 to 3, and may further reduce the mask complexity.

Improvement of pattern fidelity in triangle arrangement LCD's color filter by an optical proximity correction mask design method

For portable digital displays, the pattern of a color filter should resemble the design pattern as much as possible to avoid contrast loss within the liquid crystal display (LCD). The higher the quality requirement of a LCD, the smaller the difference between the design pattern and the actual pattern of a color filter, also known as ‘pattern fidelity’, should be. In this work, we use the histogram of the different segments between the designed pattern and the actual pattern to define the critical shape error (CSE) indices, CSEavg, CSE90 and CSE80, the area percentage indices of the ‘white zone’ (WZ Area%) and the ‘over zone’ (OZ Area%), and the maximum segment width of the ‘over zone’ (Max. CSE width). Through the evaluation of all indices of the optical proximity correction (OPC) patterns, we choose the optimal OPC pattern, the hexagonal OPC pattern circumscribing a circle of diameter 3 µm, and have a color filter with very good pattern fidelity.

Electron beam lithography process for advanced optical masks

The requirements for advanced optical masks have been tightened according to the accelerated lithography roadmap for semiconductor manufacturing. The accuracy of the optical mask may be affected by the pattern exposure tools, the materials, and the processes. Higher acceleration voltage e-beam pattern exposure was evaluated with a chemically amplified resist. With the higher acceleration voltage e-beam system, proximity effect correction is needed to control the critical dimension (CD). CD linearity is maintained down to 400 nm for different kinds of patterns by adopting the 50 kV e-beam system and proximity effect correction. The results show that the method is an attractive candidate for fabrication of next generation optical masks. Dry etching is effective in achieving small feature sizes, such as optical proximity correction (OPC), with high pattern fidelity. Loading effects were evaluated, and inductively coupled plasma dry etching was found to be stable against those effects. Fabrication of the OPC pattern designed for a 0.15 μm rule device was demonstrated with these methods.