High-precision transfer devices

The etching resistance of a resist is simply a function of how well the material withstands the pattern transfer processes used in device manufacturing. Its resistance must be sufficiently high to allow precise transfer of the resist image into the underlying substrate with < 10% linewidth change. This is not an easy... 

A pneumatic device (D) for transferring liquid into the cell to maintain the level of the liquid is a considerable convenience for high-precision work, it is a necessity. The bottle shown (D) is mounted on a horizontal axis so that it can be rotated and the tip brought in contact with the liquid a vertical bottle supported on a platform that can be raised or lowered can serve the same purpose. 

If high precision is important, a volumetric pipet or other high-precision device must be used for the transfer of to the container and a volumetric flask must be used for the container. Also, if too much water is added by mistake, such that the solution level is above the required calibration line, the solution must be discarded and the entire process repeated. Removing solution from the container to correct such a situation is not an acceptable method for accurately preparating solutions. The reason for this is that the solution being removed likely contains some solute, and thus the concentration of the solute would change in an indeterminable way if some were removed. 

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