Hiroshi Matsumoto

High-accuracy correction of critical dimension errors taking sequence of large-scale integrated circuits fabrication processes into account

We previously proposed a new method to correct critical dimension (CD) errors appearing in large-scale integrated circuit (LSI) fabrication processes, such as long range loading effect, local flare, and micro loading effect. The method provides high accuracy correction dimensions when using the pattern modulation method (method correcting CD errors by controlling figure sizes of LSI patterns). Now the case that several processes cause CD errors when a layer of an LSI pattern is fabricated on a wafer is discussed. These CD errors are corrected by generalizing the method proposed previously and taking the sequence of processes into account. It is shown from numerical calculation that the method can suppress the CD error to less than 0.01 nm with three iterations, under the condition that the maximum CD errors by micro loading effect and flare are 10 nm and 20 nm, respectively. It is strongly suggested that our methods will provide the necessary CD accuracies in the future.

Multi-beam mask writer MBM-1000 and its application field

NuFlare has started development of multi-beam mask writer MBM-1000 aiming to apply to N5 and to release in Q4 2017. MBM-1000 is based on large area projection optics with shaping aperture array plate, blanking aperture array (BAA) plate, single cathode and inline/realtime data path for vector data rasterization and bitmap dose correction. It is designed to accomplish higher throughput than EBM series (variable shaped beam (VSB) writers) with massive beam array, higher resolution by using 10-nm beam size and 10-bit dose control, and better writing accuracy with more write passes. Configuration of MBM-1000 and flow of data path processing are described. Write time estimation suggests MBM-1000 has advantage over VSB writer with shot count > 200 Gshot/pass and resist sensitivity >75 μC/cm2. Printing test of 20 nm hp 1:1 line and space pattern with ZEP-520 resist showed better beam resolution of MBM-1000 alpha tool than EBM series.

Multi-beam mask writer MBM-1000

Multi-beam mask writer MBM-1000 has been developed for N5. It is designed to accomplish high resolution with 10 nm beam and high throughput with 300 Gbps blanking aperture array (BAA) and inline real-time data path. It is equipped with function of pixel level dose correction (PLDC) to improve patterning resolution, which is method specific to multi-beam writer. Design concept of MBM-1000 is described. Writing test is carried out to demonstrate performance of MBM-1000 and PLDC function.

Proposal of an extended loading effect correction for EBM-8000

To enhance global CDU attained by our EB mask writer EBM-8000, we examined extending the loading effect correction (LEC) function to treat plural of loading effects, for instance, develop and etch loading. Here, we propose a LEC dose composition method, assuming uniquely-defined relation between amount of dose modulation and resultant CD change. Sets of LEC dose maps (pairs of base dose maps and proximity backscattering ratio maps) are converted to sets of CD change maps which are summarized to create a set of dose maps used for writing. This paper describes the correction procedure and possible applications of the method.

Enhancement of global CD correction and data processing in EB mask writer EBM-8000

We report our development of fogging effect correction method aimed for EBM-8000, our newest series of EB mask writers for mask production of 22nm half-pitch generation and for mask development of 16nm half-pitch generation. We refined the method of fogging effect correction by taking account of dose modulation for proximity effects correction and loading effect correction into fogging effect correction, greatly reducing theoretical error. Writing experiment has shown that our method based on the threshold dose model is effective, though deviation from the model is observed.