Method and apparatus for irradiating a semiconductor material surface by laser energy
A laser irradiation and semiconductor technology, which is applied in laser welding equipment, semiconductor devices, semiconductor/solid-state device manufacturing, etc., can solve the problems of small beam size and diameter, difficult to detect, and impossible
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no. 1 approach
[0032] According to a first embodiment of the present invention, a method for irradiating a semiconductor material is provided, comprising:
[0033] - irradiating an area of the surface of the layer of semiconductor material with a first laser having laser irradiation parameters to melt at least part of the area;
[0034] - and control of the irradiation process by adjusting the irradiation parameters;
[0035] It is characterized in that the method further comprises determining the depth of the melted region portion.
[0036] By determining the depth of the melted area portion, the laser irradiation process is accurately monitored in real time at the level of the semiconductor material surface, resulting in consistency between different processed surface areas and in electronic device performance.
[0037] The semiconductor material layer can be any material suitable for semiconductor applications, such as, but not limited to, undoped silicon, doped silicon, implanted sili...
example 2
[0073] - Detection of inconsistent semiconducting materials: transitions in melting time or depth of melting when the same irradiation parameters are maintained may indicate transitions in material or material quality of the semiconducting layer.
[0074] - Detection of inconsistent processes before the laser annealing step: The shift in melting time or the shift in melting depth can be used as a passive monitor during laser irradiation which can help control the quality of the process prior to laser annealing. For example, if an oxide layer or another layer is present on top of the surface to be melted and tends to melt time shifted while keeping the melt depth the same, the consistency of the layer can be controlled and an alarm obtained if desired.
example 1
[0076] Melting time determination:
[0077] The processing laser was a high energy xenon chloride excimer laser emitting at 308 nm. The irradiated area is between 2 and 4cm 2 between rectangular surfaces, and an energy density of 2 to 6 J / cm over the irradiated area 2 between. The parameters are selected so as to achieve melting of the irradiated areas on the wafer.
[0078] The diagnostic laser is a laser diode emitting continuously in the red region of the spectrum at 632 nm, which is directed on the wafer at a position within the area planned to be irradiated. Reflections of the laser beam off the surface of the wafer are captured by detectors, eg silicon photodiodes.
[0079] As the processing laser illuminates the wafer, the signal from the detector is digitized by a data acquisition card (oscilloscope or equivalent), and the digitized signal is read by the control system. Due to the change in reflectivity of silicon, the signal increases when silicon melts and decre...
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