Abstract:
This invention relates to a system for delivering megasonic energy to a liquid, comprising: - one or more megasonic transducers, each transducer having a single operating frequency within an ultrasound bandwidth and comprising two or more groups of piezoelectric elements arranged in one or more rows; and - a megasonic generator means for driving the one or more transducers at frequencies within the bandwidth, the generator means being adapted for changing the voltage applied to each group of piezoelectric elements so as to achieve substantially the same maximum acoustic pressure for each group of piezoelectric elements, the generator means and transducers being constructed and arranged so as to produce ultrasound within the liquid. Such a system may be part of an apparatus for cleaning a surface of an article such as a semiconductor wafer or a medical implant.
Abstract:
The present invention is related to a method for cleaning a surface of a substrate (6,30), in particular a semiconductor substrate such as a silicon wafer, by the steps of :Positioning the substrate (6,30) so that the surface is at a distance from a piezo-electric transducer (2,32), supplying a cleaning liquid (5) between the substrate and the transducer, applying an oscillating acoustic force to the cleaning liquid by actuating the transducer (2,32), i.e. by applying an alternating current and voltage to said transducer, moving the transducer with respect to the substrate or vice versa, wherein at several points in time during said movement the the following sequence of steps is performed : measuring the distance between the surface and the transducer, or measuring the phase shift between the current and voltage applied to said transducer, comparing the measured distance to a desired distance, or comparing the measured phase shift to a desired value of the phase shift, adjusting the distance between the surface and the transducer so that said distance is maintained substantially equal to said desired distance, or so that said phase shift remains equal to said desired value of the phase shift. The invention is equally related to an apparatus suitable for performing the method of the invention.
Abstract:
The present invention is related to a method for cleaning a surface of a substrate (6,30), in particular a semiconductor substrate such as a silicon wafer, by the steps of :Positioning the substrate (6,30) so that the surface is at a distance from a piezo-electric transducer (2,32), supplying a cleaning liquid (5) between the substrate and the transducer, applying an oscillating acoustic force to the cleaning liquid by actuating the transducer (2,32), i.e. by applying an alternating current and voltage to said transducer, moving the transducer with respect to the substrate or vice versa, wherein at several points in time during said movement the the following sequence of steps is performed : measuring the distance between the surface and the transducer, or measuring the phase shift between the current and voltage applied to said transducer, comparing the measured distance to a desired distance, or comparing the measured phase shift to a desired value of the phase shift, adjusting the distance between the surface and the transducer so that said distance is maintained substantially equal to said desired distance, or so that said phase shift remains equal to said desired value of the phase shift. The invention is equally related to an apparatus suitable for performing the method of the invention.
Abstract:
According to the method of the invention, a spot on a layer (3) of a 2D semiconductor material deposited on a support substrate (2;20,21) is irradiated so as to generate excitons, so that photons are emitted from the layer. The photoluminescence spectrum is recorded and this is repeated for different values of the charge carrier concentration in the layer. The modulation of the charge carrier concentration may be realized by modulating the output power of the light source (1) used to irradiate the sample, preferably a laser. The relation is thereby recorded between the ratio of the photoluminescence intensity of a first peak in the spectrum related to radiative recombination from indirect bandgaps to the intensity of a second peak in the spectrum related to radiative recombination from direct bandgaps, and the carrier concentration. This recorded relation is fitted to a theoretical model of the ratio that takes into account multiple recombination mechanisms, radiative and non-radiative. From this fitting process, the trap density within the bandgap is derived. The invention is equally related to an apparatus configured to perform the method of the invention.
Abstract:
According to an aspect of the present inventive concept there is provided method for releasing a graphene layer from a template substrate on which the graphene layer is provided, the method comprising: subjecting the graphene layer and the template substrate to a water treatment by soaking the graphene layer and the template substrate in water such that water is intercalated between the template substrate and the graphene layer; and subjecting the graphene layer and the template substrate to a delamination process, thereby releasing the graphene layer from the template substrate.
Abstract:
The present invention is related to a method and apparatus for cleaning semiconductor substrates, wherein a nucleation structure is mounted facing a surface of the substrate to be cleaned, said nucleation structure having nucleation sites on a surface of the structure. The substrate and structure are brought into contact with a cleaning liquid, which is subsequently subjected to acoustic waves of a given frequency, e.g. megasonic waves. The nucleation template features easier nucleation formation than the surface that needs to be cleaned. This could be obtained in different ways: make a template with a higher contact angle when in contact with the liquid than the substrate surface to be clean. Therefore, bubbles nucleate on the structure and not on the surface to be cleaned. The invention is related to an apparatus comprising a tank, a transducer and a means for mounting the substrate and nucleation structure in the above manner.