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SEMI P30-0997 © SEMI 1997, 2004 2 positioning of a measured pa ttern, measuring, and wafer unloadi ng. 4.1.9.4 static rep eatability — variations in average measurement values acquired in a sequence for a pattern. This i…

1 SEMI P30-0997 © SEMI 1997, 2004

SEMI P30-0997 (Reapproved 1104)

PRACTICE FOR CATALOG PUBLICATION OF CRITICAL DIMENSION

MEASUREMENT SCANNING ELECTRON MICROSCOPES (CD-SEM)

This standard was technically approved by the Global Micropatterning Committee and is the direct

responsibility of the Japanese Micropatterning Committee. Current edition approved by the Japanese

Regional Standards Committee on July 23, 2004. Initially available at www.semi.org September 2004; to be

published November 2004. Originally published in 1997.

1 Purpose

1.1 The purpose of this practice is to define terms

listed in Critical Dimension-Scanning Electron

Microscopes (CD-SEM).

1.2 This document is designed to create a common

understanding between suppliers and users.

2 Scope

2.1 This practice applies to terms listed in the CD-SEM

catalog.

2.2 This practice also applies to terms listed in the

estimate and purchasing specification.

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 and health practices and determine

the applicability of regulatory or other limitations prior

to use.

3 Referenced Documents

3.1 None.

4 Terminology

4.1 Definitions

4.1.1 accelerating voltage — the mean kinetic energy

of primary electrons converted into voltage.

4.1.2 alignment — corrects coordinates for positions

and specimen stage. Matching the coordinates of a

wafer and a specimen stage in order to address

measured patterns formed on a wafer.

4.1.3 alignment error — distance from the pattern

center to screen center after alignment. This is the

maximum distance between the screen center and a

target pattern after addressing by its coordinates and

completing alignment.

4.1.3.1 automatic pattern determination method — the

pattern selection method based on the automatic pattern

recognition system.

4.1.4 Critical Dimension Measurement SEM (CD-

SEM) — selects fine patterns on a wafer and measure

dimensions. Here, wafers include SEMI standards

(defined sizes) only. The operation is normally in the

following “sequence”: Transport -> Stage Travel ->

Positioning -> Measuring -> Transport.

4.1.5 image resolution — resolution between two

points. This is the minimum resolving distance

between any two points in an image.

4.1.6 magnification — the ratio of a deflection width

on a display to that on a measurement pattern.

Compares the deflection width on the screen and on the

pattern.

4.1.6.1 manual pattern determination method —

operator uses cursors, etc. The pattern selection method

is accomplished by the operator placing cursors on the

measurement pattern.

4.1.7 measurable range — measurement range to

guarantee static and dynamic repeatability as well as

linearity. Measuring dimensions guaranteed to be

within the specification of static repeatability, dynamic

repeatability, and linearity.

4.1.8 measurement pattern determination method —

identifies the pattern to be measured. This method is

used to identify the pattern to be measured. It is

performed by automatic pattern recognition, or

instructions from the operator.

4.1.9 measurement precision

4.1.9.1 dynamic repeatability — variations between

the nominal and measured dimensions. This is the

maximum dispersion of measurements from the best

approximate line defined between the nominal and

measured dimensions.

4.1.9.2 linearity — variations in measurement values

without changing device and wafer conditions. This is

the closeness of agreement between the measured

values obtained by measuring a pattern repeatedly

without any changes of measurement conditions.

4.1.9.3 reproducibility — variations in average

measurement values acquired in a sequence during a

certain period. This is the closeness of agreement

between the mean values obtained by measuring a

pattern repeatedly at stated period with wafer loading,

wafer alignment, stage traveling to a measurement site,

SEMI P30-0997 © SEMI 1997, 2004 2

positioning of a measured pattern, measuring, and

wafer unloading.

4.1.9.4 static repeatability — variations in average

measurement values acquired in a sequence for a

pattern. This is the closeness of agreement between the

measured values obtained by measuring a pattern with

wafer loading, wafer alignment, stage traveling to a

measurement site, positioning of a measured pattern,

measuring, and wafer unloading.

4.1.10 measurement target — kind of measurement

pattern. The measurement pattern, such as line, space,

pitch, hole, box-in-box, etc.

4.1.11 operation method — the control method of

operation sequence. There are three methods: auto,

semi-auto, and manual.

4.1.11.1 automatic operation method — the operation

method controlled by a computer automatically, after an

operator sets a carrier on the equipment. The computer

follows the commands written in a recipe. Uses a

recipe on a computer.

4.1.11.2 manual operation — the operation method

controlled by an operator without a recipe. Uses an

operator.

4.1.11.3 semi-auto operation — the operating method

controlled by a computer and an operator. The operator

confirms the results of each command in a recipe using

an automatic operation. Uses a recipe with an operator.

4.1.12 pattern edge determination method — uses a

computer or an operator to look at the image. This is

the method for determining the edge position of a given

pattern, which is calculated by computer algorithm or

by operator instructions.

4.1.12.1 automatic pattern edge determination — there

are several methods, such as the threshold method, the

linear approximation method, and the curve fitting

method. This is the method used to determine the edge

position automatically by calculating from the line

profile signal of the secondary or back-scattered

electrons. The calculations are performed using the

aforementioned three algorithms.

4.1.12.2 manual pattern edge determination method —

the operator measures the distance between cursors per

image edge area. This method is used to determine the

edge position manually by calculation based on the

width between cursors, which are set to the

measurement pattern edges by operator.

4.1.13 pattern positioning error — distance from the

center of screen after positioning. This is the maximum

distance between the screen center and a target pattern

after pattern positioning.

4.1.14 permissible air vibration — the maximum air

vibration that can provide the guaranteed resolution.

4.1.15 permissible floor loading capability — the

minimum floor loading capability where the equipment

can be settled.

4.1.16 permissible stray magnetic field — the

maximum change in the stray magnetic field that can

provide the guaranteed resolution.

4.1.17 permissible floor vibration

— the maximum

floor vibration that can provide the guaranteed

resolution.

4.1.18 positioning of measured patterns — moving

pattern to the center screen (center of image field).

4.1.19 stage positioning error — variations when

moving stage to a selected location repeatedly without

correction. This is the positioning error of stage, which

occurs when traveling to the same site repeatedly

without electron beam deflection.

4.1.20 stage positioning range — range on a wafer that

can be measured by moving the wafer. This is the

measurable range of a measured wafer placed on a

specimen stage with stage moving.

4.1.21 throughput — the number of processed wafers

(per unit time, which is calculated from the time

required for processing under pre-scheduled

measurement sequence and conditions).

4.1.22 transport — transferring wafer from a wafer

carrier to a specimen stage, or the reverse process.

4.1.23 wafer size — wafer diameter.

3 SEMI P30-0997 © SEMI 1997, 2004

5 Listed Items

The following are desirable items and examples for listing in the CD-SEM catalog.

5.1 Equipment name

5.2 Model

5.3 Performance

5.3.1 Throughput ___________ wafers/h (Example: 30 wafers / h)

5.3.2 Image resolution ___________ nm (Example: 5 nm)

5.3.3 Measurement precision

5.3.3.1 Static repeatability ___________ nm ( 3 

n-1

) (Example: 5 nm ( 3 

n-1

))



5.3.3.2 Dynamic repeatability ___________ nm ( 3 

n-1

) (Example: 5 nm ( 3 

n-1

))



5.3.3.3 Reproducibility ___________ nm ( 3 

n-1

) (Example: 5 nm ( 3 

n-1

))



5.3.3.4 Linearity ___________ nm ( 3 

n-1

) (Example: 5 nm ( 3 

n-1

))



5.3.3.5 Precision guaranteed range ___________ µm –

___________ µm

(Example: 0.2 µm ~ 10 µm, 5,000 ~

200,000 x)

5.4 Function

5.4.1 Wafer transport/Stage system

5.4.1.1 Transport method ___________ (Example: double cassette support

to C to C method)

5.4.1.2 Stage stopping error ___________µm (Example: ± µm)

5.4.1.3 Wafer size ___________ mm (Example: 100, 125, 150, 200 mm)

5.4.1.4 Positioning range ___________ (Example: whole wafer surface)

5.4.2 Alignment system

5.4.2.1 Alignment method ___________ (Example: uses optical image)

5.4.2.2 Alignment precision ___________± µm (Example: µm)

5.4.2.3 Pattern positioning method ___________ (Example: moving cursor)

5.4.2.4 Pattern positioning precision ___________ (Example: ± 0.1 µm)

5.4.3 Electro-optical system

5.4.3.1 Electron gun type ___________ (Example: LaB6 / schottky / C-FE)

5.4.3.2 Accelerating voltage ___________ (Example: 0.5  1.5 kV, 0.1 kV

step)

5.4.3.3 Probe current ___________ (Example: 0.2  10 pA)

5.4.3.4 Magnification ___________ (Example: 100  200,000 times)

5.4.4 Measurement

5.4.4.1 Measurement pattern ___________ (Example: line / hole / overlay)

5.4.4.2 Pattern determination method ___________ (Example: automatic (pattern

recognition) / manual/cursor)

5.4.4.3 Pattern edge determination

method

___________ (Example: automatic (line

approximation) / threshold method)

5.4.4.4 Operation method ___________ (Example: auto / semiauto / manual)

5.4.4.5 Communication protocol ___________ (Example: SECS)

5.4.5 Vacuum exhaust system ___________ (Example: TMP ( 500 L / s ) 1 unit,

SIP ( 20 L / s ) 2 units )

5.5 Installation conditions

5.5.1 Dimensions width______mm,

depth______mm,

height______mm

(May be included in the standard

diagram.)

5.5.2 Standard layout diagram

5.5.3 Mass ___________ kg

5.5.4 Permissible environmental

conditions

5.5.4.1 Loading capability ___________ Kg / m

5.5.4.2 Stray magnetic field, ___________ T p  p