Uniformity control of metal-based photoresists
An EUV photoresist composition includes paramagnetic particles that are adapted to block EUV radiation. The magnetic manipulation of the paramagnetic particles within a deposited layer of EUV photoresist can beneficially impact focus control and the achievable line width roughness during subsequent photolithographic processing. A spin-coating apparatus for dispensing the EUV photoresist composition onto a substrate includes a plurality of concentric electromagnets located beneath the substrate that influence the distribution of the paramagnetic particles in the photoresist layer.
1. A method of depositing a layer on a substrate, comprising:
dispensing a photoresist material comprising a resin, paramagnetic particles, and a solvent onto a portion of a substrate while rotating the substrate at a first number of revolutions per minute for a first time period;
rotating the substrate for a second time period different from the first time period, and at a second number of revolutions per minute greater than the first number to disperse the photoresist material over the substrate to form a photoresist layer; and
applying an attractive magnetic force to the paramagnetic particles from below the substrate, while rotating the substrate at the second number of revolutions per minute, to yield a greater paramagnetic particle distribution within a lower half of the photoresist layer thickness than within an upper half of the photoresist layer thickness, a radially uniform distribution of the paramagnetic particles throughout the photoresist layer, and an increased EUV sensitivity within the photoresist layer;
wherein applying the attractive magnetic force comprises applying power to a plurality of concentric electromagnets disposed beneath the substrate, the plurality of concentric electromagnets including a first electromagnet and a second electromagnet separated by a first radial gap, and a third electromagnet separated from the second electromagnet by a second radial gap, wherein a size of the first radial gap is different from a size of the second radial gap.
2. The method of claim 1 , wherein the attractive magnetic force is applied after dispersing the photoresist material over the substrate.
3. The method of claim 1 , wherein the attractive magnetic force is applied prior to evaporation of the solvent from the photoresist material.
4. The method of claim 1 , wherein after applying the attractive magnetic force the paramagnetic particle distribution within the photoresist layer is radially homogeneous.
5. The method of claim 1 , wherein the attractive magnetic force modifies a line width roughness of the photoresist material.
6. The method of claim 1 , further comprising arranging the plurality of concentric electromagnets such that the first radial gap and the second radial gap are each between approximately 0.1 centimeters (cm) and approximately 5.0 cm.
7. The method of claim 1 , further comprising providing the plurality of concentric electromagnets such that each of the plurality of electromagnets has a radial width between approximately 0.5 centimeters (cm) and approximately 5.0 cm.
8. The method of claim 1 , further comprising independently controlling each concentric electromagnet of the plurality of concentric electromagnets to provide a specified magnitude and duration of attractive magnetic force.