Microstructure defect detection

A method of inspecting a microstructure, comprising:

• a. charging up a microstructure;
• b. interrogating the charged microstructure with a charged-particle beam to obtain an apparent dimension for at least one high aspect ratio feature of the microstructure, the apparent dimension differing in size from an actual physical dimension of the high aspect ratio feature as a result of a surface potential surrounding the high aspect ratio feature, the surface potential being affected by an electrical connectivity of a material proximate the high aspect ratio feature;
• and
• c. comparing said apparent dimension with reference information about the microstructure to identify a defect.

A computer-readable medium containing instructions for controlling a charged-particle-beam system to perform a method for inspecting a semiconductor wafer, the method comprising:

• a. applying low energy charged particles of less than 3 keV to the wafer to negatively charge up the wafer over a region having at least two feedthrough holes, a first feedthrough hole having a physical diameter of substantially the same size as that of a second feedthrough hole, the first hole being disposed over a material having an electrical connectivity different from that of the second hole;
• b. scanning a charged-particle beam over said negatively charged region while detecting secondary particles to produce a detector signal;
• c. determining from the detector signal apparent diameters of the at least two feedthrough holes, the apparent diameter of the first hole differing in size from the physical diameter of the first hole because of a surface potential surrounding the first hole;
• and
• d. comparing the apparent diameters of said at least two feedthrough holes with reference information to identify a defect.

A computer program product comprising a computer usable medium having computer-readable program code embodied therein for controlling a charged-particle-beam system comprising:

• a. computer-readable program code configured to cause the charged-particle-beam system to charge up a microstructure, the microstructure having at least one high aspect ratio feature;
• b. computer-readable program code configured to cause the charged-particle-beam system to interrogate the charged microstructure with a charged-particle beam to obtain an apparent dimension for at least one feature of the microstructure, the apparent dimension differing in size from an actual physical dimension of the feature as a result of a surface potential surrounding the high aspect ratio feature, the surface potential being affected by an electrical connectivity of a material proximate the high aspect ratio feature;
• and
• c. computer-readable program code configured to cause the charged-particle-beam system to compare said apparent dimension with reference information about the microstructure to identify a defect.

A method of inspecting a semiconductor wafer, comprising:

• a. negatively charging a region of the wafer, the region having a first feedthrough hole and a second feedthrough hole, the first hole having a first physical diameter and being disposed over a first material having a first electrical connectivity, the second hole having a second physical diameter and being disposed over a second material having a second electrical connectivity, the first electrical connectivity differing from the second electrical connectivity, the first and second physical diameters being substantially equal;
• b. scanning a charged-particle beam over the negatively-charged region while detecting secondary particles to produce a detector signal;
• and
• c. determining from the detector signal apparent diameters of the first and second holes, the apparent diameter of the first hole differing in size from the apparent diameter of the second hole,
• wherein the apparent diameters of the first and second holes are affected by the materials underlying the respective holes, the apparent diameters providing information as to the first and second materials located beneath the respective first and second holes.

A method of inspecting a semiconductor wafer, comprising:

• a. negatively charging a region of the wafer, the region having a first feedthrough hole and a second feedthrough hole, the first hole having a first physical diameter and being disposed over a first material having a first electrical connectivity, the second hole having a second physical diameter and being disposed over a second material having a second electrical connectivity, the first electrical connectivity being different from the second connectivity, the first and second diameters being substantially equal;
• b. scanning a charged-particle beam over the negatively-charged region while detecting secondary particles so as to produce a detector signal;
• c. constructing from the detector signal an image of the region of the wafer;
• d. determining apparent diameters of the first and second holes;
• e. optimizing at least one parameter to enhance a feature enlargement effect to differentiate between the size of the apparent diameters of the first and second holes, the apparent diameters of the first and second holes providing information as to the first and second materials located beneath the respective first and second holes;
• and
• f. comparing the apparent diameters of the first and second holes with reference information to identify a defect.