Water-soluble chromophore containing copolymers for bottom antireflection coating applications in lithography
✍ Scribed by Iain Mcculloch; Ping Lu; Ming Kang
- Book ID
- 101251517
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 354 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Regulatory concerns in the semiconductor industry from both VOC emissions and solvent handling have prompted the desire to introduce water-based formulations in spin-coating fabrication processes. As resolution demands for i-line lithography are driven to finer feature size and architecture, the need for antireflection coatings as a means of eliminating feature distortions from back reflected light is increasing. Common image irregularities, such as reflective notching and standing wave effects, can be effectively eliminated through application of an antireflection coating of optimal thickness between the resist layer and substrate. This work describes the design and development of novel side-chain methacrylate copolymers for use in water-based antireflection coating formulations. A pendant chromophore is incorporated into the polymer structure to allow optimization of the critical coating optical properties, refractive index, and absorption coefficient. The polymer solubility parameter and crosslinking density can be tailored by incorporation of appropriate functionality to allow compatibility with the device fabrication process. Terpolymers were designed, which were water-soluble, had a thermally activated crosslinking mechanism, and contained a keto-ester azobenzene chromophore that was highly absorbing at i-line wavelength. Optical properties of polymer films were collected by spectroscopic elipsometry and utilized in the design process to identify the optimum chromophore structure. Lithographic images, fabricated utilizing these coatings, were of excellent quality, allowing critical dimension resolutions of less than 0.3 m.