Abstract ---
Optical samples ---
E-beam samples ---
Description ---
Details (in Czech)
Description The test structures on the chip are etched as reliefs in the polished surface of a single crystal silicon substrate. For their preparation, electron beam lithography and anisotropic etching techniques are used. The geometrical patterns of the testing structures have sharp edges and stable dimensions in the dependence on temperature (linear dilatability of the substrate is 2.5 ´ 10-6 K-1). The chip of the 8 ´ 8 mm size contains nine different test structures in total. They are positioned in the centre of the chip and take up an area of 3 ´ 3 mm (each of the nine test structures has a size of 1 ´ 1 mm). The individual types of test structures are, therefore, easy to reach even in case of small mechanical shifts of the specimen manipulator. The arrangement of the individual types of test structures is schematically shown in fig. 1, and in the following their description is presented. The numbers of the individual types correspond to those given in fig. 1.
*) The least 0.01 ´
0.01 mm (10 ´
10 μm) square is the whole-area-etched relief. The metrics of dimensions is related to the outer edges of the lines that form the contour of the square of the given size.
**) The sequence of X dimensions: 1, 0.8, 0.6, 0.4, 0.2, 0.1, 0.08, 0.06, 0.04 and 0.02 mm. To facilitate orientation, lines which form rectangles of 0.1 mm dimensions and smaller are markedly thinner than lines forming contours of rectangles of 0.2 mm dimensions and greater. The least 0.02 ´
0.015 mm (20 ´
15 μm) rectangle is the whole-area-etched relief. The metrics of dimensions is related to the outer edges of the lines that create the contour of the rectangle of the given size.
The gratings formed by lines of dimensions 3, 10, 30 and 100 μm are denoted at the left-hand (or right-hand) side by a numeral that is identical with the dimension of the respective grating. This numeral denotation unambiguously defines the distribution of the types of test structures even for general positions of the chip in the working chamber of SEM. The numeral denotations of dimensions of gratings as well as other texts located on the chip are not intended for measurement and testing. |
Usage - magnification checking Use of the Secondary Electron Image (SEI) mode is recommended when the test chip is employed. Definition of dimensions and their accuracy A) Gratings The grating size is defined by the distance of edges of two neighbouring geometrical patterns forming the grating (i.e. lines in the case of gratings 1, 2, 3, 7, 8 and 9, and square areas in the case of grating 5). The dimensions of gratings are the same in both mutually perpendicular directions X and Y. The dimensional accuracy of the individual gratings is guaranteed as follows:
The above mentioned values are valid for the laboratory temperature 23 ° C. The dimensions of geometrical patterns forming the grating structures are not metrically described, and they are therefore not guaranteed. However, for any particular grating, these dimensions can be found out at work by means of the above mentioned dimension of the grating. The dimensions of the patterns (lines) forming the 3 μm grating usually approach 1 μm and they can be therefore utilized also for the de termination of magnification as high as 105´ .B) Contours of squares and rectangles The dimensions in the X-direction and the corresponding dimensions in the Y-direction given in the description of patterns 4 and 6 are guaranteed in all cases with an accuracy of ±1 μm. General data The chip is easy to take out from the transport box by pressing gently the stamping in which it is positioned. The chip can be coated with metal if necessary. The most suitable method is cathode sputtering. The metal coating thickness should not exceed 50 nm. To remove dust from the chip, use a piece of soft plastic foam moistured by some detergent diluted in a small volume of water. Wipe the chip by making several circular motions and afterwards rinse it by a stream of distilled water from a syringe. To remove the remaining water from the chip, use a stream of pure gas (nitrogen from the pressure vessel or developer). Never use alkaline solutions to clean the chip or to remove a metal coating from its surface. If organic solvents are used for removing fat spots, do not let remains of these substances dry on the chip. Remove them from the chip surface by an intensive stream of pure gas. We wish you much success at your work and will be glad if you inform us about your experience with our test chip. |