SOI Wafers - Used in Neural Probes Applied Watts -

Readily available 25-µm thick, Standard Device Layer, Silicon On Insulator (SOI) wafers are used for neural probes, with a 1-µm buried oxide (as shown below Figure 1). The previous thickness of 12--µm thick was not as strong as the 25- µm being used today.

FIGURE 1.

Step 1 utilizes an available Applied Watts (AW) SOI wafer that has a Standard Device Layer of 25-µm, a Buried Oxide Layer of 1-µm, and a Base Silicon Layer of 550-µm. This wafer is available in quantities of (25), (50) or more.

Step 2 deposits a 0.5-µm layer of Silicon Nitride using AW available LPCVD process, which is a low-pressure chemical vapor deposition.

Step 3 etches the holes utilizing a Reactive Ion Etch (RIE), a wet etch process that takes approximately 30 minutes.

Step 4 is an oxide deposition using LPCVD closing some holes and leaving channels for the electrodes not shown in this illustration.

APPLICATION SUCCESS

The end result was a successful microfabrication process that utilized the SOI technology requiring only RIE to define the outline of the device. Signals were able to be captured with the customer’s final product and used for the addition of on-board electronics. The additions of 6mm long by 70-µm wide pins were used primarily for sensory input.

The thickness of the Standard Device Layer on the SOI wafer, determines the customer’s finished product. In addition a thinning process can be added, such as etch, to the manufacturing so that components are set into the back side. This is a great feature since it gives ease to wirebonding and handling.

SOI wafers can be purchased from our stock or built to your specification. Call us or email us today to discuss your application!

We look forward to hearing from you soon,

AW