A diamond substrate producing method includes a belt-shaped separation layer forming step of applying a laser beam to a diamond ingot as relatively moving the ingot and a focal point of the laser beam in a [110]-direction perpendicular to a (110)-plane, thereby forming a belt-shaped separation layer extending in the [110]-direction inside the ingot, an indexing step of relatively moving the ingot and the focal point in an indexing direction parallel to a (001)-plane and perpendicular to the [110]-direction, a planar separation layer forming step of repeating the belt-shaped separation layer forming step and the indexing step to thereby form a planar separation layer parallel to the (001)-plane inside the ingot, the planar separation layer being composed of a plurality of belt-shaped separation layers arranged side by side in the indexing direction, and a separating step of separating a substrate from the diamond ingot along the planar separation layer.

A diamond substrate producing method includes a belt-shaped separation layer forming step of applying a laser beam to a diamond ingot as relatively moving the ingot and a focal point of the laser beam in a [110]-direction perpendicular to a (110)-plane, thereby forming a belt-shaped separation layer extending in the [110]-direction inside the ingot, an indexing step of relatively moving the ingot and the focal point in an indexing direction parallel to a (001)-plane and perpendicular to the [110]-direction, a planar separation layer forming step of repeating the belt-shaped separation layer forming step and the indexing step to thereby form a planar separation layer parallel to the (001)-plane inside the ingot, the planar separation layer being composed of a plurality of belt-shaped separation layers arranged side by side in the indexing direction, and a separating step of separating a substrate from the diamond ingot along the planar separation layer.

A fabrication method of a thin film transistor is provided. The fabrication method includes: forming a gate electrode, an active layer, a drain electrode and a source electrode on the base substrate, in which the active layer includes a channel region and a second portion on both sides of the channel region, and at least a portion of the channel region is overlapped with the gate electrode; and performing a laser annealing process on a side of the base substrate by using a laser, in which the channel region is shielded without being irradiated by the laser, a resistivity of the second portion of the active layer is lower than a resistivity of the channel region, and the second portion of the active layer is connected with the source electrode and the drain electrode. A thin film transistor, an array substrate and a display device are further provided.

A wafer cleaning apparatus, a method of cleaning wafer and a method of fabricating a semiconductor device are provided. The method of fabricating the semiconductor device includes disposing a wafer on a rotatable chuck, irradiating a lower surface of the wafer with a laser to heat the wafer, and supplying a chemical to an upper surface of the wafer to clean the wafer, wherein the laser penetrates an optical system including an aspheric lens array, the laser penetrates a calibration window, which includes a first window structure including a first light projection window including first and second regions different from each other, a first coating layer covering the first region of the first light projection window, and a second coating layer covering the second region of the first light projection window, and the first coating layer and the second coating layer have different light transmissivities from each other.

A wafer cleaning apparatus, a method of cleaning wafer and a method of fabricating a semiconductor device are provided. The method of fabricating the semiconductor device includes disposing a wafer on a rotatable chuck, irradiating a lower surface of the wafer with a laser to heat the wafer, and supplying a chemical to an upper surface of the wafer to clean the wafer, wherein the laser penetrates an optical system including an aspheric lens array, the laser penetrates a calibration window, which includes a first window structure including a first light projection window including first and second regions different from each other, a first coating layer covering the first region of the first light projection window, and a second coating layer covering the second region of the first light projection window, and the first coating layer and the second coating layer have different light transmissivities from each other.

A laser processing method for processing a substrate having a device formed on the front side, an electrode pad being formed on the device. The method includes applying a pulsed laser beam to the back side of the substrate at a position corresponding to the electrode pad, thereby forming a fine hole in the substrate so that the fine hole reaches the electrode pad, detecting first plasma light generated from the substrate by the application of the pulsed laser beam to the substrate and also detecting second plasma light generated from the electrode pad by the application of the pulsed laser beam to the electrode pad, and stopping the laser beam when the second plasma light is detected. Time intervals of the pulsed laser beam repeatedly applied to the same fine hole are set to 0.1 ms or more.

A laser processing method for processing a substrate having a device formed on the front side, an electrode pad being formed on the device. The method includes applying a pulsed laser beam to the back side of the substrate at a position corresponding to the electrode pad, thereby forming a fine hole in the substrate so that the fine hole reaches the electrode pad, detecting first plasma light generated from the substrate by the application of the pulsed laser beam to the substrate and also detecting second plasma light generated from the electrode pad by the application of the pulsed laser beam to the electrode pad, and stopping the laser beam when the second plasma light is detected. Time intervals of the pulsed laser beam repeatedly applied to the same fine hole are set to 0.1 ms or more.

A semiconductor device according to an embodiment includes a semiconductor substrate comprising a first face, and a second face on an opposite side to the first face. A semiconductor element is provided on the first face of the semiconductor substrate. A polycrystalline or non-crystalline first material layer is provided at least on an outer edge of the first face of the semiconductor substrate. A second material layer is provided on the second face of the semiconductor substrate. The second material layer transmits laser light.

A semiconductor device according to an embodiment includes a semiconductor substrate comprising a first face, and a second face on an opposite side to the first face. A semiconductor element is provided on the first face of the semiconductor substrate. A polycrystalline or non-crystalline first material layer is provided at least on an outer edge of the first face of the semiconductor substrate. A second material layer is provided on the second face of the semiconductor substrate. The second material layer transmits laser light.

A semiconductor device according to an embodiment includes a semiconductor substrate comprising a first face, and a second face on an opposite side to the first face. A semiconductor element is provided on the first face of the semiconductor substrate. A polycrystalline or non-crystalline first material layer is provided at least on an outer edge of the first face of the semiconductor substrate. A second material layer is provided on the second face of the semiconductor substrate. The second material layer transmits laser light.