Resistance polymerization

Polymers are only marginally important in main memories of semiconductor technology, except for polymeric resist films used for chip production. For optical mass memories, however, they are important or even indispensable, being used as substrate material (in WORM, EOD) or for both substrate material and the memory layer (in CD-ROM). Peripheral uses of polymers in the manufacturing process of optical storage media are, eg, as binder for dye-in-polymer layers or as surfacing layers, protective overcoatings, uv-resist films, photopolymerization lacquers for repHcation, etc. 

The output from the semibatch model GASPP permits a detailed look at the way in which polymerization resistances increase during the course of a run. Figure 3 shows how these resistances increase with yield for a run using the intermediate activity catalyst (kg = 0.00638 cm/sec), with 50 mg TiCil3 loading. Overall resistance, is the sum of the individual resistances in... 

The most widely used polymeric resist materials are random copolymers, in which monomers with different functionalities are randomly distributed in the polymer matrix so that the final properties are based on the average level... 

The resolution capability of a resist is directly related to resist contrast (7) which, for a negative resist, is related to the rate of crosslinked network formation at a constant input dose. It is somewhat more complicated for a positive resist being related to the rate of chain scission and the rate of change of solubility with molecular weight with the latter being markedly solvent dependent. Contrast, like sensitivity, is governed by the type of chemical reactions that occur in the polymeric resist and is affected by molecular parameters such as molecular weight distribution and chemical composition. 

Unfortunately, the incorporation of silicon into polymeric resists can alter the desirable materials characteristics. A decrease in the glass transition temperature often accompanies the inclusion of silicon into a resin, and most silicon substituents will drastically change the solubility properties of the parent polymer. For example, polymerization of propylpentamethyldisiloxyl methacrylate affords rubbery, low Tg polymers that are... 

Materials Synthesis and Characterization. In addition to the requirements of etching resistance, sensitivity, solubility and high glass transition temperature (Tg), one of the criteria used in designing both a negative and positive electron-beam resist system was synthetic simplicity. The trimethylsilylmethyl appendage allows the incorporation of silicon into polymeric resists without adverse synthetic complications. Standard free radical or condensation polymerization techniques can be employed with appropriately substituted monomers that are readily available. 

The linewidth differences between the mask and the corresponding resist pattern were precisely evaluated for isolated line and isolated space patterns. The deviation in linewidth versus linewidth shows a maximum or minimum with inorganic resists (13). This behavior is in contrast to that for organic polymeric resists, in which the linewidth deviations gradually increase as the mask feature size decreases. This difference may be explained in terms of selfcompensation of the optical proximity effect due to lateral Ag diffusion. 

Inorganic resists have many advantages over conventional polymeric resists, especially in regard to resolution, linewidth control latitude, focus depth tolerance, and dry processability. These features make them very suitable for application to submicron VLSI fabrication. Efforts to improve processing technologies will open the way for practical use in LSI fabrication. 

Polymers with Si-Bearing Functional Groups. An alternative to polymers with silicon in the backbone is polymeric resist systems with silicon-... 

L. T. Romankiw, A Review of Plating Through Polymeric Resist Masks, Extended Abstracts of the Electrochemical Society, 79-2, No. Abstract No. 462, 1165-1166, The Electrochemical Society Inc., Pennington, NJ (1979). 

Where nanoscale dimensions are involved, this necessitates the use of vacuum ultraviolet light or x rays. Penetration of the x rays into the semiconductor must be avoided to prevent damage to the crystal, so wavelengths of 1.3 nm or 4.5 nm are preferred because the polymeric resist exhibits an absorption depth of about 1 micron at these wavelengths. 

---