Yoji Maruyama

Stress‐controlled x‐ray mask absorber using pulse‐current gold plating

The application of pulse‐current gold plating has been studied in the fabrication of x‐ray mask patterns to attain uniform thickness and low stress. Pulse‐current plating with low average current density (iav) has proven effective in improving uniform plating thickness over a wide range of pattern sizes. This result can be explained through the duplex‐diffusion layer model. Stress in the gold plated by low iav becomes compressive. However, this stress can be eliminated by annealing. This annealing effect is attributable to the contraction in volume of plated gold due to the thermal desorption of hydrogen atoms.

Electron Beam Mask Fabrication for MOSLSI's with 1.5 µm Design Rule

A new mask set for n-MOSFET test devices and circuits is made to investigate the feasibility of electron beam mask fabrication with very small linewidths. The mask set is basically designed with a 1.5 µm design rule, but contained finer lines to clarify problem areas. A negative electron resist PGMA and a positive electron resist P(MMA-AN) are used. Linewidth control is better than ±0.1 µm with PGMA and ±0.2 µm with P(MMA-AN). Pattern placement accuracy is ±0.15 µm and overlay accuracy is ±0.25 µm. The characteristics of MOSFETs and RAMs fabricated using the 1.5 µm design rule masks, are measured.