The MAPLE Process

In the MAPLE process, the desired polymer/solvent mix is frozen inside of a deposition chamber.

The polymer/solvent mixture is injected into a cup surrounded by a large copper reservoir, which is then filled with liquid nitrogen which freezes the mixture. The frozen mixture then acts as the target for an incident pulsed laser beam.

Using a pulsed laser, a small section of the frozen target will be evaporated in a very short period of time, throwing a small section of the mixture into the vapor phase. The polymer material directed at the substrate will then be deposited while the solvent is pumped away (if you choose the correct solvent). This process has been used to successfully deposit a wide variety of polymer and biological thin film materials.

A six position MAPLE and RIR-PLD target holder cooled with LN2. Assembly can index and all targets rotate.  Located at Jefferson Labs and used with the FEL.

Lasers

The original MAPLE work utilized an excimer laser, but IR lasers provide much better polymer film quality. The reason is the energy per photon for excimer lasers operating at 248 nm (KrF) is ~5.4 eV.  This is enough energy to break polymer chains and ligands and reduce the functionality of the deposited polymer materials. PVD Products' MAPLE systems utilize an Er:YAG laser that operates at 2.9 microns where each photon has only about 0.3 eV of energy. Thus, polymer functionality remains intact since the polymer chains are not fractured by the low energy photons. The strong absorption of water at this wavelength makes it a good solvent material in many cases. PVD Products can also provide systems with alternative lasers.

Sample Injection

PVD Products' MAPLE system utilizes a unique injection process that allows you to freeze your polymer/solvent mix in-situ after the chamber has been purged of water vapor and other gasses. Our MAPLE systems utilize a quick target cool-down and quick target heat-up assembly to maximize throughput. Our rotating LN2 cooled target holder assembly makes excellent thermal contact with the cooling block cooling the polymer/solvent mix to well below -170°C.

Design

PVD's MAPLE system is built around our popular box-style Nano PLD chamber with large hinged front door for easy access to the internal components. This provides for easy sample transfers through the front door. The systems come complete with a fully enclosed optical train and laser beam rastering, turbo pumping package, and laptop computer control utilizing LabVIEW software. Valve packages can be manual or all electropneumatic as required.  A wide variety of standard options are also available.

Inside the single target MAPLE system