Radiant energy – Inspection of solids or liquids by charged particles – Methods
Reexamination Certificate
1998-12-03
2001-06-26
Berman, Jack (Department: 2878)
Radiant energy
Inspection of solids or liquids by charged particles
Methods
C250S341400
Reexamination Certificate
active
06252228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an analysis of the morphology of a semiconductor wafer's bulk defect and surface defect.
2. Description of the Related Art
Generally speaking, a semiconductor device uses a wafer of Si crystal as its primary material. The device is fabricated through processes where several films are formed on the wafer and then patterned. The Si crystal wafer can be classified into various types according to the ways of growing its crystals. Recently, there has been chiefly used a wafer whose crystals are grown in Czochralski's method.
However, wafers may be formed with bulk defects or surface defects on them during the process of growing the crystals. To prevent in advance failures caused by those defects formed and present on the wafer itself during semiconductor device manufacture, an analysis of the defects is carried out. According to prior art, however, the morphology of the bulk defect or surface defect cannot be investigated precisely, although the analysis of their distribution or location is enabled. Due to this problem, the causes of failure occurring during semiconductor device manufacturing using wafers or produced from the semiconductor device are not found out exactly. The unattainable analysis of morphology of the bulk defect or surface defect existing within a wafer reduces the semiconductor device's reliability because it prevents the cause of the semiconductor device's failure from being examined.
SUMMARY OF THE INVENTION
Therefore, in order to overcome such drawbacks of the prior art, an objective of the present invention is to provide a precise analysis of the morphology of a bulk defect or a surface defect existing on a semiconductor wafer. This analysis allows the investigation failures caused by those defects and thus enhancing semiconductors' reliability.
To accomplish these and other objects, there is provided a method of analyzing the morphology of a bulk defect on a semiconductor wafer, including determining a location of a bulk defect existing on the wafer; marking an indication near a position where the bulk defect is present; milling the wafer using the indication, to thereby make a specimen with which the bulk defect's morphology can be analyzed; and analyzing the specimen to obtain the bulk defects' morphology.
The bulk defects whose morphology is to be analyzed may be present as deep as 5-250 &mgr;m from the wafer's surface.
The determination of the location ofthe bulk defect preferably includes cutting the wafer to form a section and the location of the bulk defect is represented as a combination of a coordinate of the depth from the section and a coordinate of the depth from the wafer's surface. The location of the bulk defect is preferably detected by projecting a laser beam perpendicularly to the surface and perpendicularly to the section of the wafer, using a BMD (Bulk Micro Defect) analyzer. The determination ofthe location preferably includes marking a preliminary indication for whichever coordinate is determined first and using the preliminary indication to control the projecting of the laser beam on the other coordinate.
The indication is preferably marked using a FIB (Focused Ion Beam). It is preferable that the wafer made as the specimen with which the bulk defects' morphology can be analyzed is milled with a FIB (Focused Ion Beam). Alternatively, before the milling, the wafer may be cut into a predetermined size including an area containing the bulk defect. Then the milling includes milling the predetermined size of the wafer preferably with a Focused Ion Beam.
The analysis of the bulk defects' morphology using the specimen is preferably carried out with a TEM (Transmission Electron Microscopy).
For another aspect of the present invention, there is provided an analysis of the morphology of a bulk defect on a semiconductor wafer, including: projecting a laser beam to a section of the wafer cut perpendicular to its surface, using a BMD analyzer that enables the location of the bulk defect existing in the wafer to be found out, to thereby detect how deep the bulk defect is placed from the section; projecting the laser beam perpendicular to the wafer's surface to thereby detect how deep the bulk defect is placed from the surface; marking an indication near a position where the bulk defect is present, with a FIB (Focused Ion Beam); milling the wafer using the FIB (Focused Ion Beam) at the reference ofthe indication, the wafer being made as the specimen with which the bulk defect's morphology can be analyzed; and analyzing the specimen using a Transmission Electron Microscopy to obtain the bulk defect's morphology.
For still another aspect of the present invention, there is provided an analysis of the morphology of surface defects on a semiconductor wafer, including: determining the location of a surface defect in the surface of the wafer; marking an indication near a position where the surface defects are present; milling the wafer using the indication, to thereby make a specimen with which the surface defect's morphology can be analyzed; and analyzing the specimen to obtain the surface defect's morphology.
The surface defect whose morphology is to be analyzed is preferably present within as deep a range as 10 &mgr;m from the wafer's surface. The location of the surface defect is preferably detected by projecting a laser to the wafer's surface at a predetermined angle using a BMD analyzer. It is preferable that the predetermined angle is between 10° and 30°. The indication is preferably marked using a FIB (Focused Ion Beam). The wafer made as the specimen with which the bulk defects' morphology can be analyzed is preferably milled with a FIB (Focused Ion Beam). Alternatively, before milling, the wafer may be cut into a predetermined size including an area containing the surface defect. The analysis of the surface defects' morphology using the specimen is preferably carried out with a Transmission Electron Microscopy.
For yet another aspect of the present invention, there is provided an analysis of the morphology of a surface defect on a semiconductor wafer, including: projecting a laser beam to the wafer's surface, using a BMD analyzer to thereby detect the location of the surface defect existing within 10 &mgr;m from the wafer's surface; marking an indication near a position where the surface defect is present, with a FIB (Focused Ion Beam); milling the wafer using the FIB (Focused Ion Beam) at the reference of the indication, the wafer being made as the specimen with which the surface defects' morphology can be analyzed; and analyzing the specimen using a Transmission Electron Microscopy to obtain the surface defect's morphology.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5422498 (1995-06-01), Nikawa et al.
patent: 5534698 (1996-07-01), Ohshima et al.
patent: 5892225 (1999-04-01), Okihara
Cho Sung-hoon
Heo Tae-yeol
Berman Jack
Jones Volentine, L.L.C.
Samsung Electronics Co,. Ltd.
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