Various technologies are described herein pertaining to electrochemical etching of a semiconductor controlled by way of a laser that emits light with an energy below a bandgap energy of the semiconductor.

Various technologies are described herein pertaining to electrochemical etching of a semiconductor controlled by way of a laser that emits light with an energy below a bandgap energy of the semiconductor.

A layered structure includes a substrate, a porous layer over the substrate, an epitaxial layer grown directly over the porous layer, and a semiconductor device in the epitaxial layer. The porous layer has a higher resistivity than the substrate. A porosity of the porous layer reduces radio frequency (RF) bleeding from the semiconductor device into the substrate.

A layered structure includes a substrate, a porous layer over the substrate, an epitaxial layer grown directly over the porous layer, and a semiconductor device in the epitaxial layer. The porous layer has a higher resistivity than the substrate. A porosity of the porous layer reduces radio frequency (RF) bleeding from the semiconductor device into the substrate.

A method includes: in a semiconductor wafer including a first semiconductor layer and a second semiconductor layer adjoining the first semiconductor layer, forming a porous region extending from a first surface into the first semiconductor layer; and removing the porous region by an etching process, wherein a doping concentration of the second semiconductor layer is less than 10.sup.−2 times a doping concentration of the first semiconductor layer and/or a doping type of the second semiconductor layer is complementary to a doping type of the first semiconductor layer.

A substrate processing apparatus includes a substrate rotator, a processing liquid supply, an anode and a cathode, and a controller. The substrate rotator is configured to hold and rotate a substrate. The processing liquid supply is configured to supply a processing liquid to the substrate held by the substrate rotator. The anode and the cathode are configured to apply a voltage to the processing liquid supplied from the processing liquid supply. The controller is configured to control the substrate rotator, the processing liquid supply, and the anode and the cathode. The controller allows, by contacting the anode and the cathode with the processing liquid independently, the processing liquid in contact with the anode and the processing liquid in contact with the cathode to be supplied to the substrate while being spaced apart from each other when the substrate is rotated.

A substrate processing apparatus includes a substrate rotator, a processing liquid supply, an anode and a cathode, and a controller. The substrate rotator is configured to hold and rotate a substrate. The processing liquid supply is configured to supply a processing liquid to the substrate held by the substrate rotator. The anode and the cathode are configured to apply a voltage to the processing liquid supplied from the processing liquid supply. The controller is configured to control the substrate rotator, the processing liquid supply, and the anode and the cathode. The controller allows, by contacting the anode and the cathode with the processing liquid independently, the processing liquid in contact with the anode and the processing liquid in contact with the cathode to be supplied to the substrate while being spaced apart from each other when the substrate is rotated.

An exemplary distribution system, apparatus and method can be provide for chemical and/or electrolytic surface treatment of a substrate in a process fluid. The distribution system can comprise a distribution body and a control unit. The distribution body can be configured to direct a flow of the process fluid and/or an electrical current to the substrate. The distribution body can comprise at least a first distribution element and a second distribution element. The control unit/device can be configured to control the first distribution element and the second distribution element separately from one another.

The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

The present disclosure provides an etching solution, including an ionic strength enhancer having an ionic strength greater than 10.sup.−3 M in the etching solution, wherein the ionic strength enhancer includes Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+, N(CH.sub.3).sup.+, or N(C.sub.2H.sub.5).sup.4+, a solvent, and an etchant.