Apparatus and method for producing a crystalline film on a substrate surface
An apparatus and method is provided for coating a surface of a material with a film of porous coordination polymer. A first substrate having a first surface to be coated is positioned in a processing chamber such that the first surface is placed in a substantially opposing relationship to a second surface. In some embodiments, the second surface is provided by a wall of the processing chamber, and in other embodiments the second surface is provided by a second substrate to be coated. The first substrate is held such that a gap exists between the first and second surfaces, and the gap is filled with at least one reaction mixture comprising reagents sufficient to form the crystalline film on at least the first surface. A thin gap (e.g., having a thickness less than 2 mm) between the first and second surfaces is effective for producing a high quality film having a thickness less than 100 μm. Confining the volume of the reaction mixture to a thin layer adjacent the substrate surface significantly reduces problems with sedimentation and concentration control. In some embodiments, the size, shape, or average thickness of the gap is adjusted during formation of the film in response to feedback from at least one film growth monitor.
1. An apparatus having at least one processing chamber for producing a crystalline film on at least one substrate surface, wherein the crystalline film comprises at least one porous coordination polymer, the apparatus comprising:
a) at least one substrate positioner for positioning at least a first substrate having a first surface to be coated in the processing chamber, wherein the first substrate is positioned such that the first surface is placed in a substantially opposing relationship to a second surface provided by a second substrate or a wall of the processing chamber and such that a gap exists between the first and second surfaces, the gap having an average thickness that is less than about 2 mm;
b) reagent delivery means for filling the gap with at least one reaction mixture comprising reagents sufficient to form the crystalline film of porous coordination polymer on at least the first surface;
c) at least one film growth monitor arranged to monitor growth of the film; and
d) at least one controller in communication with the substrate positioner and the film growth monitor, wherein the controller is programmed to control the substrate positioner, according to feedback or signals from the film growth monitor, to move the first substrate in order to change the average thickness of the gap or the tilt angle of the first surface relative to the second surface.
2. The apparatus of claim 1 , wherein the substrate positioner is adjustable to change the position of the first substrate such that the average thickness of the gap between the first and second surfaces is in the range of about 0.1 μm to 1 mm.
3. The apparatus of claim 1 , wherein the substrate positioner is adjustable to change the position of the first surface relative to the second surface such that the average thickness of the gap is in the range of 1 to 500 μm.
4. The apparatus of claim 1 , wherein the substrate positioner comprises a multi-axis positioning stage arranged to adjust both the average thickness of the gap and the tilt of the first surface relative to the second surface.
5. The apparatus of claim 1 , further comprising a second substrate holder for holding the second substrate having the second surface in the substantially opposing relationship to the first surface.
6. The apparatus of claim 1 , wherein the controller is further programmed to control the reagent delivery means, according to feedback or signals from the film growth monitor, to change flow rates of the reagents, thereby adjusting respective concentrations of the reagents in the reaction mixture.
7. The apparatus of claim 1 , wherein the at least one film growth monitor is arranged to monitor growth of the film at multiple points on the first surface, and the controller is further programmed to control the substrate positioner, according to signals from the film growth monitor indicating different growth rates at the multiple points, to change the tilt angle of the first surface relative to the second surface so that the gap is wedge-shaped.