A direct write-on-wafer system with 3 million individually controlled proton beams is implemented on 12 monolithic silicon substrates spanning a 300mm wafer. Direct write does not need a reticle for resist exposure.
Using protons to expose the resist has many advantages over electrons or photons. Protons are 1800 times more massive than electrons and the resist is more than 100 times more sensitive to these protons than an equivalent energy electron. The effective proton wavelength of 0.5nm is much smaller than any expected feature size. The resist is exposed by collateral electrons produced as the proton decelerates after hitting the resist layer. Resolution is high as these low energy electrons do not scatter very far. The 3.5KeV protons do not produce the resist fogging backscattered electrons that plague the 50KeV e-beams.
A challenge in accelerating protons is reducing their transverse momentum. Traditional designs use hot ions sources with 10 to 100 electron volts of transverse energy. Our solution uses a cold ion source with less than one electron volt of energy. All of the proton energy will be longitudinal along the length of the channel. Channel wall passivation puts a positive charge on the walls that keep the protons focused in the center of each channel.
Each accelerator chip has 262K channels etched into silicon dioxide trenches that are 50nm wide, 50nm deep, and 40mm long on a 100nm pitch. Channel pitch accuracy of one nanometer can be achieved with standard lithographic techniques. Variations in channel depth and width have little effect on accelerator performance. Beam spot size is controlled by the beam current, the beam voltage, and the distance between the beam exit port and the wafer.
The dual head p-Beam printing system has a total of more than 6million addressable linear ion accelerators.
The major components of the Transmute ProBeam are:
The Print Head:
The Print Head does this and this and this. (link to Print Head in Technology section)
The Ion Injector
The Ion Injector does this and this and this. (link to Ion Injector in Technology section.)