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SEMI M3-0304 © SEMI 1978, 2004 2 3.3 Other Stand ard 2 ANSI/ASQC Z1. 4-1993 — Sampli ng Procedures a nd Tables for Inspect ion by Attributes NOTICE : Unless otherwise indicated, all docum ents cited shall be the latest p…

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SEMI M3-0304 © SEMI 1978, 2004 1
SEMI M3-0304
SPECIFICATIONS FOR POLISHED MONOCRYSTALLINE SAPPHIRE
SUBSTRATES
This specification was technically approved by the Global Silicon Wafer Committee and is the direct
responsibility of the North American Silicon Wafer Committee. Current edition approved by the North
American Regional Standards Committee on December 4, 2003. Initially available at www.semi.org
February 2004; to be published March 2004. Originally published in 1978; last published November 2003.
1 Purpose
1.1 Sapphire substrates are utilized for heteroepitaxial
growth of silicon films for certain types of device
structures. The properties of the films depend in part
on the properties of the substrate used. These
specifications are intended to provide specifications for
the criteria necessary for growth of films suitable for
device production.
2 Scope
2.1 These specifications cover requirements for five
sizes (from 2 inch to 150 mm) of monocrystalline high-
purity polished sapphire substrates. Dimensional and
crystallographic orientation characteristics are the only
standardized properties set forth herein. A purchase
specification may require that additional physical
properties be defined. Many of these properties are
listed, together with test methods suitable for
determining their magnitude. Additional information
and recommended specification levels for several of
these properties are provided in Related Information
sections.
2.2 These specifications are directed specifically to
sapphire substrates with one polished surface.
Substrates polished on both sides, or unpolished, or
with epitaxial deposits, are not covered; however,
purchasers of such substrates may find these
specifications to be a useful guide in defining their
requirements.
2.3 Appendix 1 covers dimensional requirements for
reclaimed 3 inch sapphire substrates.
2.4 For referee purposes, U.S. customary units shall be
used for substrates of 2.0 and 3.0 in. nominal diameters,
and SI (System International, commonly called metric)
units for 100 mm and larger diameter substrates.
NOTICE: This standard does not purport to address
safety issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety health practices and determine the
applicability of regulatory or other limitations prior to
use.
3 Referenced Standards
3.1 SEMI Standards
SEMI M1 — Specifications for Polished
Monocrystalline Silicon Wafers
SEMI MF26 — Test Methods for Determining the
Orientation of a Semiconductive Single Crystal
SEMI MF523 — Practice for Unaided Visual
Inspection of Polished Silicon Wafer Surfaces
SEMI MF533 — Test Method for Thickness and
Thickness Variation of Silicon Wafers
SEMI MF534 — Test Method for Bow of Silicon
Wafers
SEMI MF671 — Test Method for Measuring Flat
Length on Wafers of Silicon and Other Electronic
Materials
SEMI MF847 — Test Methods for Measuring
Crystallographic Orientation of Flats on Single Crystal
Silicon Wafers by X-Ray Techniques
SEMI MF928 — Test Methods for Edge Contour of
Circular Semiconductor Wafers and Rigid Disk
Substrates
SEMI MF1810 — Test Method for Counting
Preferentially Etched or Decorated Surface Defects in
Silicon Wafers
SEMI MF2074 — Guide for Measuring Diameter of
Silicon and Other Semiconductor Wafers
3.2 ASTM Standard
1
E 122 — Practice for Choice of Sample Size to
Estimate the Average Quality of a Lot or Process
1 Volume 14.02 of the Annual Book of ASTM Standards, ASTM
International, 100 Barr Harbor Drive, West Conshohoken, PA 19428-
2959, USA. Telephone: 610.832.9585, Fax: 610.832.9555, Website:
www.astm.org.
SEMI M3-0304 © SEMI 1978, 2004 2
3.3 Other Standard
2
ANSI/ASQC Z1.4-1993 — Sampling Procedures and
Tables for Inspection by Attributes
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
4 Terminology
4.1 Definitions
4.1.1 lot — for the purposes of these specifications, (a)
all of the substrates of nominally identical size and
characteristics contained in a single shipment, or (b)
subdivisions of large shipments consisting of substrates
as (a) above which have been identified by the supplier
as constituting a lot.
4.1.2 sapphire (in silicon-on-sapphire technology) —
single crystal aluminum oxide (Al
2
O
3
) having a definite
orientation that allows epitaxial silicon deposition.
4.1.3 substrate — the polished sapphire slice upon
which the epitaxial layer of silicon is grown.
5 Ordering Information
5.1 Purchase orders for sapphire substrates furnished to
these specifications shall include the following items:
5.1.1 Nominal diameter (see Table 1),
5.1.2 Crystal growth method (see Note 1),
5.1.3 Surface orientation (see Table 1 and Figures 1
and 2),
5.1.4 Lot acceptance procedures (see Section 9),
5.1.5 Certification (if required) (see Section 12), and
5.1.6 Packing and marking (see Section 13).
5.2 The following items may be specified optionally in
addition to those listed in Section 5.1:
5.2.1 Crystal perfection,
5.2.2 Surface defect and contaminant levels,
5.2.3 Impurities,
5.2.4 Front surface finish quality level (see Figures R2-
1 through R2-4),
5.2.5 Back surface finish,
5.2.6 Secondary flat (see Figure 3),
5.2.7 Flatness (see Table 2), and
5.2.8 Edge Profile.
2 American Society for Quality Control, 611 East Wisconsin Avenue,
Milwaukee, WI 53202. Website: www.asqc.org.
NOTE 1: The crystal growth method (for example,
Czochralski or EFG ribbon) is difficult to ascertain in the
finished substrates. Verification test procedures or
certification of these characteristics (see Section 12) shall be
agreed upon between the supplier and the purchaser.
NOTE 2: Items in Section 5.2 are less commonly specified
than the others but are included for completeness as
parameters for which methods of evaluation have been
developed.
6 Dimensions and Permissible Variations
6.1 The material shall conform to the dimensions and
dimensional tolerances as specified in Table 1 for the
following parameters.
6.1.1 Diameter,
6.1.2 Center Point Thickness,
6.1.3 Total Thickness Variation,
6.1.4 Primary Flat Length,
6.1.5 Secondary Flat Length,
6.1.6 Flat Locations, and
6.1.7 Bow.
6.2 The orientation of the substrate material shall be
identified by a flat system as defined in Section 11.
6.3 If specified in the purchase order or contract the
front surface flatness shall be identified in accordance
with the classification system in Table 2.
6.4 If specified in the purchase order or contract, the
edge shall be rounded and beveled.
7 Materials and Manufacture
7.1 The material shall consist of slices from sapphire
grown by the process specified in the purchase order or
contract.
8 Physical Requirements
8.1 The material shall conform to the crystallographic
orientation details listed in Table 1 (see Figure 1).
8.2 The following items, if included, shall conform to
the requirements specified in the purchase order or
contract:
8.2.1 Crystal perfection,
8.2.2 Surface defect and contaminant levels (See
Related Information 1 for surface defect definitions and
Table R1-1 for suggested allowable levels of surface
defects.),
8.2.3 Amount of impurities,
SEMI M3-0304 © SEMI 1978, 2004 3
8.2.4 Front surface finish quality level (see Related
Information 2 and Figures R2-1 through R2-4 for
information on recommended front surface finish
quality levels), and
8.2.5 Back surface finish (see Related Information 2
for recommended back surface finish level).
9 Sampling
9.1 Unless otherwise specified, ASTM Practice E 122
shall be used. When so specified, appropriate sample
sizes shall be selected from each lot in accordance with
ANSI/ASQC Z1.4-1993. Each quality characteristic
shall be assigned an acceptable quality level (AQL) and
lot total percent defective (LTPD) value in accordance
with ANSI/ASQC Z1.4-1993 definitions for critical,
major, and minor classifications. If desired and so
specified in the contract or order, each of these
classifications may alternatively be assigned cumulative
AQL and LTPD values. Inspection levels shall be
agreed upon between the supplier and the purchaser.
10 Test Methods
10.1 Dimensions — Measure as follows:
10.1.1 Diameter — Determine by a method agreed
upon between the supplier and the purchaser at
locations specified in Configuration 1 of
SEMI MF2074.
NOTE 3: Sapphire substrates are highly susceptible to surface
damage. While the mechanical dimensions of a slice can be
measured by use of tools such as micrometer calipers and
other conventional techniques, the substrate may be damaged
physically in ways that are not immediately evident. Special
care must therefore be used in the selection and execution of
measurement methods.
10.1.2 Thickness, Center Point — Determine at the
center of the substrate (Point 2 in Figure 4) in
accordance with SEMI MF533.
10.1.3 Total Thickness Variation (5 point) —
Determine in accordance with SEMI MF533, except
that thickness measurements shall be made at the five
locations in Figure 4 instead of the locations specified
in SEMI MF533. Points 1, 3, 4, and 5 in Figure 4,
which define the locations of the edge measurements,
are located 6 mm in from the wafer periphery.
10.1.4 Flat Length — Determine in accordance with
SEMI MF671.
10.1.5 Bow — Determine in accordance with
SEMI MF534.
10.2 Flat Orientation — Determine in accordance with
SEMI MF847.
10.3 Surface Orientation — Determine in accordance
with the x-ray method of SEMI MF26.
10.4 Crystal Perfection — Unless otherwise specified,
determine in accordance with SEMI MF1810.
10.5 Surface Defects and Contamination — Determine
defects in accordance with SEMI MF523.
10.6 Other Impurities — Determine by methods agreed
upon between the supplier and the purchaser.
10.7 Front Surface Finish — Determine by methods
agreed upon between the supplier and the purchaser.
10.8 Back Surface Finish — Determine by methods
agreed upon between the supplier and the purchaser.
10.9 Flatness — Determine by a method agreed upon
between the supplier and the purchaser.
10.10 Edge Profile — Determine by a method agreed
upon between the supplier and the purchaser. Method
B of SEMI MF928 is a non-destructive way of
evaluating the shape of the edge profile; if this method
is used, the template to be used shall be agreed upon
between the supplier and the purchaser.
11 Flat System
11.1 Figures 2 and 3 describe the primary and
secondary flat system.
11.1.1 Primary Flat: 45° ± 2° in the counter-clockwise
direction from the projection of the c-axis along an r-
plane.
11.1.2 Secondary Flat (Optional): 90° ± 2° in the
counter-clockwise direction from the primary flat,
along an r-plane.
11.2 The a-axis lies between the two flats bisecting the
90° angle. Projection of the c-axis lies 45° in the
clockwise direction from the primary flat and 90° in the
clockwise direction from the a-axis.
12 Certification
12.1 Upon request of the purchaser in the contract or
order, a manufacturer’s or supplier’s certification that
the material was manufactured and tested in accordance
with this specification, together with a report of the test
results, shall be furnished at the time of shipment.
12.2 In the interest of controlling inspection costs, the
supplier and the purchaser may agree that the material
shall be certified as “capable of meeting” certain
requirements. In this context, “capable of meeting”
shall signify that the supplier is not required to perform
the appropriate tests in Section 11. However, if the
purchaser performs the test and the material fails to