Method and apparatus for non-invasive, non-intrusive, and un-grounded, simultaneous corona deposition and SHG measurements
Apparatus is described for performing simultaneous corona deposition and surface electric field induced second harmonic (EFISH) measurements. Example designs include systems including corona guns having a focus tube for deposition of corona charge with windows therein for passage of a laser beam incident on and reflected from a sample surface. Various designs may also employ masks proximal the distal end of the focusing tube and/or proximal the sample surface. In some implementations, the apparatus is used to make ungrounded and therefore non-invasive measurements, for example, on dielectric on semiconductor such as, e.g., interface state density (D it ), flatband voltage (V fb ) and/or lifetime measurements.
1 . A system for optically interrogating a sample accompanied by application of electric charge to said sample, said system comprising:
an optical source configured to emit an incident light beam towards said sample;
a corona discharge source disposed with respect to the sample to provide said electric charge to the sample; and
an optical detection system configured to detect an output light beam from the sample,
wherein said corona discharge source comprises a focus ring comprising at least one wall, said focus ring having proximal and distal ends and an opening at the distal end through which said electric charge from said corona discharge source exits toward said sample, said at least one wall having a first window for passage of said incident light beam from said optical source at an oblique angle to said sample via said first window and the opening at the distal end of the focus ring, said first window being separated from said opening at said distal end of said focus ring with said opening at said distal end of said focus ring being more distal than said first window in said at least one wall of said focus ring.
2 . The system of claim 1 , wherein said at least one wall of said focus ring has a second window for passage of said output light beam from said sample to said optical detection system at an oblique angle with respect to said sample.
3 . The system of claim 1 , wherein said output light beam comprises a second harmonic generation (SHG) light beam.
4 . The system of claim 1 , wherein said focus ring has a tubular shape.
5 . The system of claim 1 , said corona discharge source further comprising a needle for emission of electric charge, said needle surrounded on opposite sides by said focus ring.
6 . The system of claim 1 , wherein said at least one wall of said focus ring has a tubular shape.
7 . The system of claim 1 , wherein said first window is disposed with respect to said optical source and said sample such that said incident light beam is incident on said sample at an angle of between 20 and 70 degrees with respect to a normal to said sample.
8 . The system of claim 1 , wherein said first window is disposed with respect to said optical source and said sample such that said incident light beam is incident on said sample at an angle of between 30 and 60 degrees with respect to a normal to said sample.
9 . The system of claim 1 , wherein said corona discharge source further comprises a mask closer to said sample than said focus ring.
10 . The system of claim 1 , wherein said corona discharge source further comprises a mask closer to said sample than said focus ring, said mask attached to said focus ring.
11 . The system of claim 1 , further comprising a wafer chuck for supporting said sample.
12 . The system of claim 1 , wherein said system comprises an inline system configured to be included inline of a semiconductor device processing line.
13 . The system of claim 1 , further comprising a pump light source for providing additional light to said sample.