Critical Dimension Scanning Electron Microscope (CD-SEM) recipe creation needs sample
preparation necessary for matching pattern registration, and recipe creation on CD-SEM using the
sample, which hinders the reduction in test production cost and time in semiconductor
manufacturing factories. From the perspective of cost reduction and improvement of the test
production efficiency, automated CD-SEM recipe creation without the sample preparation and the
manual operation has been important in the production lines. For the automated CD-SEM recipe
creation, we have introduced RecipeDirector (RD) that enables the recipe creation by using
Computer-Aided Design (CAD) data and text data that includes measurement information. We have
developed a system that automatically creates the CAD data and the text data necessary for the
recipe creation on RD; and, for the elimination of the manual operation, we have enhanced RD so
that all measurement information can be specified in the text data. As a result, we have established
an automated CD-SEM recipe creation system without the sample preparation and the manual
operation. For the introduction of the CD-SEM recipe creation system using RD to the production
lines, the accuracy of the pattern matching was an issue. The shape of design templates for the
matching created from the CAD data was different from that of SEM images in vision. Thus, a
development of robust pattern matching algorithm that considers the shape difference was needed.
The addition of image processing of the templates for the matching and shape processing of the CAD
patterns in the lower layer has enabled the robust pattern matching.
This paper describes the automated CD-SEM recipe creation technology for the production lines
without the sample preparation and the manual operation using RD applied in Sony Semiconductor
Kyusyu Corporation Kumamoto Technology Center (SCK Corporation Kumamoto TEC).
Changes in chemical nature of an ArF photoresist caused by various plasmas were analyzed, and it was found that the HBr plasma treatment induces a selective detachment of a heterocyclic unit of the photoresist, and the detached unit remains in the photoresist film. Thermomechanical analyses were performed, which showed that the softening temperature of the photoresist decreases by the HBr treatment, indicating that the detached heterocyclic unit acts as a plasticizer in the photoresist film. These results showed that the HBr treatment can be regarded as a softening process of the photoresist. This HBr treatment was applied to the fabrication of line patterns and it was shown that the treatment remarkably improves LWR (line width roughness) after etching. This improvement was more pronounced for the case of an isolated pattern than the case of a dense pattern. Further investigations on the HBr treatment were performed by changing the copolymerization ratio of a monomer containing the heterocyclic unit. It was shown that the reduction of LWR by the HBr treatment becomes more enhanced when the copolymerization ratio increases. However, an intensive HBr treatment was found to deteriorate LWR, showing that there is an optimum condition of the HBr treatment in terms of improving LWR.
We have developed a new pattern correction method to improve the uniformity of gate width and thus transistor characteristics. It is well known that the width of the gate pattern as exposed with an alternating phase shift mask (alt-PSM) varies along the gate width direction, owing to the optical-intensity maxima within the phase shifter regions on both sides of the gate. Since the positions of the maxima depend on the shifter height, the pattern pitch and the illumination conditions (σ and NA), the degree of distortion of the gate length also depends on these factors. We have found that the optimal segment size for optical proximity correction (OPC) of gate distortion also depends on the above factors and should be determined by simulation prior to OPC. From our simulations, shorter segments do not necessarily lead to higher correction accuracy, and the optimal size is strongly related to the degree of distortion. Based on these observations, we propose a novel correction method, in which the look-up table of optimal segment size as a function of shifter height and pattern pitch is referred to in the model-based OPC flow. The advantage of the method has been shown by comparing the correction results to those from the ordinary model-based method, with the latter focusing on the line-end regions where the distortion effects are most remarkable.