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SEMI MF674-0705 © SEMI 2003, 2005 4 10.2 Sample Mounting Bl ock and Fixture — For holding the silicon specimen at th e desired beveling an gle during the bevel-pol ishing process . 10.3 Microsc ope — Optical microscope h…
SEMI MF674-0705 © SEMI 2003, 2005 3
8.3 Wax — Glycol phthalate or other similar wax having a melting temperature of less than 150°C.
8.4 Dry Air or Nitrogen — Source of clean, dry air or nitrogen suitable for drying the specimen.
9 Procedure
9.1 If not previously done, attach the polishing pad to the rigid plate and place several drops of diamond polishing
slurry at random locations on the polishing pad surface. Spread drops of slurry in a reasonably uniform manner over
the pad so that the pad surface becomes damp and so that there are no freestanding layers of slurry. If the diamond
is suspended in paste, be sparing in the amount of paste applied to the pad.
NOTE 6: Some polishing slurry adheres to the specimen and mounting fixture and is lost every time a specimen is removed and
cleaned. Replenish the slurry on the pad regularly with a few drops of fresh slurry.
9.2 With the hot plate, heat the mounting block to the melting temperature of the wax. Mount the silicon specimen
to the block with the wax. Allow the block to cool to room temperature.
9.3 Assemble the mounting block and attach specimen to the sample mounting fixture and place this assembly on
the polishing pad in the polishing machine.
9.4 In accordance with the manufacturer's instructions for the polishing machine, polish until the specimen surface
exhibits a uniform density of random-direction scratches comparable to the pattern shown in Figure 1. For this test,
remove the polishing slurry from the specimen surface and examine that surface with the microscope.
NOTE 7: The time required to reach a uniform surface finish depends on specimen surface area, size of diamond grains, static
load applied, rate of movement of the specimen surface over the polishing pad, and previous surface finish.
NOTE 8: The coarseness of the scratch damage on the specimen surface is related to the size of diamond grit used.
a. 0.5
m Diamond b. 3 m Diamond
Figure 1
Surface Texture of Large-Area Silicon Specimen Polished with Diamond Against Chemotextile Pad
9.5 When an acceptable surface finish has been reached, thoroughly swab or flush the specimen with the solvent to
remove all diamond slurry residues. Use dry air or nitrogen to blow the specimen surface dry prior to carrying out
any spreading resistance measurements.
DIAMOND BEVEL POLISHING
10 Apparatus
10.1 Glass Plate — Of suitable area for convenient use, which has been given a frosted surface by lapping with a
water slurry of nominal 3 to 12 m aluminum oxide, or similar abrasive, and thoroughly cleaned subsequent to
lapping.
SEMI MF674-0705 © SEMI 2003, 2005 4
10.2 Sample Mounting Block and Fixture — For holding the silicon specimen at the desired beveling angle during
the bevel-polishing process.
10.3 Microscope — Optical microscope having a total magnification of at least 30× and a system for illuminating
the stage obliquely.
10.4 Hot Plate, capable of heating the mounting block and wax to 150°C.
11 Reagents and Materials
11.1 Diamond Slurry — Synthetic or natural diamond with a grain size in the range 0.05 to 0.25 m, inclusive,
suspended in a liquid or paste carrier.
11.2 Solvent — Suitable nonaqueous solvent for removing diamond slurry subsequent to polishing (see Note 5).
11.3 Wax — Glycol phthalate or other similar wax having a melting temperature of less than 150°C.
11.4 Wipe, Lint-Free Paper, or Cloth — Suitable for cleaning the glass plate.
11.5 Oil Extender — Compatible with the diamond slurry (see ¶11.1).
12 Procedure
12.1 Prior to beveling each specimen, clean the frosted surface of the glass plate by swabbing with the solvent using
the lint-free wipe.
NOTE 9: Because of the rigidity of the glass surface, excessive damage to the beveled silicon surface can result from
contamination of the polishing slurry with foreign material whose size is larger than that of the diamond grit.
12.2 Apply a small amount of diamond slurry (or paste) to the surface of the glass. Distribute the slurry (or paste)
with a clean flexible metal or plastic spatula or other lint-free applicator so that a thin, uniform film results over an
area whose dimensions are several times larger than the lateral dimension of the fixture used to support the beveling
block. An oil extender may be used to prolong the life of the slurry. The oil extender generally slows the cutting
somewhat and aids lubrication during beveling.
12.3 With the hot plate, heat the mounting block to the melting temperature of the wax. Mount the silicon specimen
to the block with the wax. Allow the block to cool to room temperature.
12.4 Assemble the sample mounting block with specimen attached to the mounting fixture, and place this assembly
on the glass plate. Lower the piston of the polishing fixture carefully and gently onto the glass plate to minimize the
risk of chipping or otherwise damaging the silicon chip.
12.5 Polish the specimen by orbital, figure-eight, or reciprocating movement of the polishing fixture over the glass
plate.
NOTE 10: Use of the above polishing procedure, wherein the specimen and its fixture are moved upon a stationary glass plate,
risks the generation of random deep scratches on the beveled surface due to accumulated coarse debris on the polishing plate. It
has been found that using a rotating glass plate while holding the specimen mounting fixture so that the leading edge of the
beveled chip always faces into the direction of plate rotation reduces the risk. However, if each chip to be beveled is positioned
at the same, or nearly the same, radial distance from the plate's center of rotation, uneven wear of the plate in the form of a
channel, or wide groove, is likely to result. Such channeling of the polishing plate can be minimized or eliminated either by
moving the specimen mounting fixture slowly along the plate radius while polishing, or by choosing a different radial position on
the plate for each chip to be beveled.
12.6 Clean and inspect the specimen periodically to determine whether an adequate amount of specimen surface has
been exposed by beveling (see Note 5).
12.7 Repeat ¶12.5 and ¶12.6 as necessary until an adequate extent of beveled surface is obtained.
NOTE 11: At the beginning of the beveling process an extremely small area of silicon supports the static load of the polishing
assembly, and pressures on the silicon are extremely high. To minimize the possibility of fracture of the edge of the silicon chip,
it has been found advisable to begin bevel polishing with a relatively slow rate of motion of the polishing assembly.
12.8 When the desired amount of specimen surface has been exposed by beveling, thoroughly clean the specimen
by flushing or swabbing with the appropriate organic solvent (see ¶11.2). Inspect the beveled surface for quality of
SEMI MF674-0705 © SEMI 2003, 2005 5
finish with the microscope. Compare the finish with the appropriate photograph of Figure 2, which shows results
obtainable with different size diamond in the range specified for two types of motion during polishing. Repolish
lightly if the finish appears to be significantly coarser than that shown in the appropriate photograph. Use dry air or
nitrogen to blow the specimen surface dry prior to carrying out any spreading resistance measurements.
NOTE 12: Clean the polishing plate regularly to remove coarse polishing residue or air-borne contaminants. This cleaning can
be done with a lint–free cloth or paper wipe and the same solvent used to clean polishing residue from the specimen. Inspect the
plate when clean. If it shows signs of scratching, burnish marks, or areas where the lapped finish has been polished smooth, relap
the plate then clean thoroughly to remove lapping debris and broken-in on scrap samples (see Note 13).
NOTE 13: A newly-frosted glass plate may not yield optimum results. Such a plate can be improved by preparing a number of
samples of scrap silicon before beveling the test specimen of interest. The best indicator of frosted glass plate condition is the
quality and uniformity of surface damage on the finished bevel.
a. 0.1
m Diamond, b. 0.1 m Diamond, c. 0.5 m Diamond,
Reciprocating Motion Figure-of-Eight Motion Reciprocating Motion
Figure 2
Surface Texture of Silicon Specimens Bevel-Sectioned with Diamond Against Ground-Glass Surface
13 Keywords
13.1 beveling; diamond polishing; resistivity; resistivity variations; sample preparation; semiconductor; silicon;
spreading resistance; spreading resistance probe (SRP)
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