Methods for controlling physical vapor deposition metal film adhesion to substrates and surfaces
A method of depositing of a film on a substrate with controlled adhesion. The method comprises depositing the film including metal, wherein the metal is deposited on the substrate using physical vapor deposition at a pressure that achieves a pre-determined adhesion of the film to the substrate. The pre-determined adhesion allows processing of the film into a device while the film is adhered to the substrate but also allows removal of the device from the substrate.
1 . A method of making a plurality of devices, comprising:
fabricating, on a substrate, a film comprising a plurality of devices including a metal layer in direct contact with the substrate, wherein the fabricating comprises:
placing the substrate in a physical vapor deposition (PVD) chamber;
setting a pressure of a gas in the chamber, wherein the pressure is in a range of 2-250 mTorr;
depositing metal on the substrate using PVD at the pressure so as to form the metal layer; wherein the PVD comprises:
ionizing the gas so as to form ionized gas particles in the chamber; and
accelerating the ionized gas particles onto a target comprising the metal in the metal layer using an electric and/or magnetic field having a power in a range of 10 Watts to 100 kilowatts; and
depositing device layers on the metal layer so as to form the film comprising the plurality of the devices comprising the metal layer;
patterning and cutting the plurality of devices in the film; and
removing each of the devices from the substrate, so that the metal layer in each of the devices is removed from the substrate and each of the devices include a portion of the metal layer, wherein:
the devices each comprise an analyte sensor and the portion of the metal layer comprises an electrode used for sensing a concentration of an analyte in an in-vivo environment in contact with the electrode.
2 . The method of claim 1 , wherein the metal layer comprises a thickness of at least 100 Å.
3 . The method of claim 1 , wherein the metal layer comprises a thickness in a range of 600-1500 Å.
4 . The method of claim 1 , wherein the devices each comprise a circuit and a surface of the metal layer comprises an electrochemically active surface.
5 . The method of claim 1 , wherein the analyte comprises glucose and the analyte sensor is a glucose sensor.
6 . The method of claim 1 , wherein the electrode comprises a counter electrode.
7 . The method of claim 1 , wherein the substrate comprises glass.
8 . The method of claim 1 , wherein the fabricating comprises controlling a degree of adhesion of the metal layer to the substrate so that the adhesion is strong enough to survive processing comprising the patterning and the cutting, but weak enough to allow the removing of the metal layer from the substrate.
9 . The method of claim 8 , wherein the controlling comprises controlling the pressure used during deposition of the metal layer on the substrate using sputtering.
10 . The method of claim 9 , wherein the pressure is determined using a method comprising:
measuring the degree of adhesion of the film to the substrate as a function of the pressure used during the PVD; and
determining the pressure that achieves the adhesion of the film to the substrate that allows the patterning and the removing comprising a lifting of the metal layer from the substrate after the patterning and the cutting.
11 . The method of claim 10 , further comprising:
measuring the degree of adhesion as a function of a plurality of PVD parameters including the pressure and other PVD parameters including at least one of the power used during the PVD, a number of layers of metal comprising the metal layer, a deposition rate, or a thickness of the metal layer, so as to determine a relative impact of the pressure, as compared to the other PVD parameters, on the degree of adhesion; and
selecting the pressure as a function of the other PVD parameters and so as to achieve a desired adhesion that allows the removing comprising the lifting of the metal layer.
12 . The method of claim 1 , wherein depositing the device layers comprises depositing a working electrode and an insulating layer, wherein:
each of the devices comprising a sensor comprising a counter electrode on a backside of the sensor;
the insulating layer is between the working electrode and the counter electrode;
the cutting comprises cutting along a line surrounding each of the devices on the substrate; and
the removing comprises peeling each of the devices from the substrate.
13 . The method of claim 1 , wherein the metal layer comprises a layer comprising pillars.
14 . The method of claim 1 , wherein the metal layer comprises a roughened layer or a non-uniform layer.
15 . The method of claim 1 , wherein the metal layer comprises a layer comprising voids or a patterned layer.