Microelectromechanical slow-wave phase shifter method of use
/The present invention provides a method of use for a monolithic device utilizing cascaded, switchable slow-wave CPW sections that are integrated along the length of a planar transmission line. The purpose of the switchable slow-wave CPW sections element is to enable control of the propagation constant along the transmission line while maintaining a quasi-constant characteristic impedance. The method can be used to produce true time delay phase shifting components in which large amounts of time delay can be achieved without significant variation in the effective characteristic impedance of the transmission line, and thus also the input/output return loss of the component. Additionally, for a particular value of return loss, greater time delay per unit length can be achieved in comparison to tunable capacitance-only delay components.
1. A method of manufacturing a microelectromechanical slow-wave phase shifter device, the method comprising the steps of:
providing a quartz substrate;
defining at least one bias line;
forming a ground isolation layer positioned where the at least one bias line enters a ground conductor;
defining at least one coplanar waveguide line;
spin coating and etching a sacrificial layer using;
removing the mask layer;
evaporating a seed layer and patterning the seed layer to define at least one microelectromechanical bridge;
gold-electroplating the at least one microelectromechanical bridge;
removing the photoresist layer and seed layer;
annealing to flatten the at least one microelectromechanical bridge;
removing the sacrificial layer; and
releasing the microelectromechanical bridges using critical point drying.
2. The method of claim 1 , wherein the quartz substrate is 500 μm in thickness.
3. The method of claim 1 , wherein the step of defining the at least one bias line further comprises defining at least one bias line having a thickness of 1000 Å.
4. The method of claim 1 , wherein the step of depositing and patterning a Si x N y layer further comprising depositing a patterning a 4000 Å Si x N y layer.
5. The method of claim 1 , wherein the step of defining at least one coplanar waveguide line further comprises defining at least one coplanar waveguide by evaporating a Cr/Ag/Cr/Au line to a thickness of 150/8000/150/1500 Å.
6. The method of claim 1 , wherein the step of spin coating and etching a sacrificial layer further comprises spin coating and etching a sacrificial layer wherein the layer thickness can be varied between about 1.5 cm to about 2 μm by varying the rotational speed of the spinner between about 2500 rpm to about 1500 rpm.
7. The method of claim 6 , wherein layer thickness between about 1.8 μm and about 2 μm.
8. The method of claim 1 , where in the step of evaporating a seed layer and patterning the seed layer to define at least one microelectromechanical bridge further comprise evaporating a 100/2000 Å Ti/Au seed layer.
9. The method of claim 1 , wherein the step of gold-electroplating the microelectromechanical bridges further comprises the step of gold-electroplating to a thickness of about 1 μm.
10. The method of claim 1 , wherein the step of annealing the device further comprises the step of annealing the device at between about 105° and about 120° to flatten the microelectromechanical bridges.