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SEMI E79-0304 © SEMI 1999, 2004 23 Sample Rapi d Characterization of Intr insic Equipment Efficiency (IEE) Four experiments were designed and exec uted with the following results: Exp. Units of Recipe i Per Experiment Va…

SEMI E79-0304 © SEMI 1999, 2004 22

RELATED INFORMATION 2

RAPID CHARACTERIZATION OF INTRINSIC EQUIPMENT EFFICIENCY

(IEE) AND THE PRODUCTIVITY EFFICIENCY PLANE

NOTICE: This related information is not an official part of SEMI E79. This related information was approved for

publication by vote of the responsible committee on December 15, 1999.

R2-1 Rapid Characterization of Intrinsic

Equipment Efficiency

R2-1.1 IEE may be rapidly characterized as follows

using a limited number of production experiments.

R2-1.2 Step 1: Design Production Experiments —

Select a limited number of scenarios to execute as

equipment experiments. It may be of interest to

characterize IEE according to either operating modes,

processing diversity, or a combination of operating

modes and process diversity.

R2-1.2.1 Determine the value-added in-process

theoretical production time per unit (VTHT) – (time per

unit) for all recipes involved. This information is

required for determining IEE. See Table A2-1.

R2-1.2.2 For assessment of operating modes,

experiments should examine only a single typical recipe

that is likely to be used most frequently. Each

experiment should examine a separate operating mode,

where examples of various equipment operational

modes may be as follows:

One wafer at a time mode (production monitor

wafer).

One batch is run, then the tool stops.

Two batches are run, then the tool stops.

Three batches are run, then the tool stops.

Continuous (cascade) mode. A larger number of

batches is run, then the tool stops.

R2-1.2.3 For assessment of process diversity, select a

limited number of representative recipes that will be

processed by a tool. This population should include at

least one recipe representing the minimum expected

processing duration and one representing the maximum.

R2-1.2.4 Each experiment should be designed and

executed to eliminate rate efficiency losses to the

greatest extent possible. It is further assumed that

quality efficiency losses are zero. Under this

approximation, (VA-OEE) = (OEE)

× (IEE).

R2-1.3 Step 2: Execute Process Experiments —

Perform process experiments recording all relevant

input variables including the configuration of lots and

wafers, and recipes. For each experiment, record the

elapsed production time using convenient means, e.g.,

stopwatch or existing data acquisition system.

R2-1.4 Step 3: Calculate Results — Calculate IEE and

throughput for each experiment. IEE may be used to

measure the effect of non-value-added overhead time

during equipment processing. Approximately:

Intrinsic Equipment Efficiency (IEE)

= (Value-Added In-Process Theoretical Time)

/(Non-Value-Added Overhead Time

+ Value-Added In-Process Theoretical Time)

R2-1.4.1 Hence, non-value-added overhead time for

each experiment may be calculated as:

Non-Value-Added Overhead Time

= [(Production Time)

- ( Value-Added In-Process Theoretical Time)]

R2-1.4.2 It should be the focus of efforts by the

equipment supplier and the end-user to reduce or

eliminate non-value-added overhead time through

improved equipment design, including scheduling

software, as well as hardware components (carrier and

wafer handling systems, valves, pumps, heaters,

coolers, etc.).

R2-1.4.3 Results may be shown in either tabular form

or plotted graphically on a Productivity Effectiveness

Plane. See Section R2-2.

SEMI E79-0304 © SEMI 1999, 2004 23

Sample Rapid Characterization of Intrinsic Equipment

Efficiency (IEE)

Four experiments were designed and executed with the

following results:

Exp.

Units of Recipe i

Per Experiment

Value-Added

In-Process

Theoretical

Production Time

Per Unit

(VTHT

)

Production

Time Per

Experiment

1 50 of recipe A 0.00670 hr/unit 3.3333 hr

2 100 of recipe B 0.00550 hr/unit 5.0000 hr

3 150 of recipe B 0.00550 hr/unit 6.0000 hr

4 300 of recipe A 0.00670 hr/unit 10.0000 hr

Effective Unit Throughput Per Experiment

= (Total Units Per Experiment)

/(Production Time Per Experiment)

Intrinsic Equipment Efficiency (IEE) Per Experiment

= [Σ

(Units of Recipe i Per Experiment × VTHT

)

/(Production Time Per Experiment)] × 100%

Non-Value-Added Overhead Time Per Experiment

= [(Production Time Per Experiment)

- Σ

(Units of Recipe i Per Experiment × VTHT

)]

Experiment

Effective

Unit

Throughput

Intrinsic

Equipment

Efficiency

Non-Value-

Added

Time

in Hours

1 15 units/hr 10.05% 2.9983 hr

2 20 units/hr 11.00% 4.4500 hr

3 25 units/hr 13.75% 5.1750 hr

4 30 units/hr 20.10% 7.9900 hr

R2-2 Productivity Efficiency Plane (PEP)

R2-2.1 It is recognized that OEE and throughput are

separate metrics whose relationship may not be

straightforward. Because theoretical production time

per unit may vary widely by recipe, good throughput

performance may not indicate correspondingly good

performance in terms of overall equipment efficiency.

Similarly, a high OEE score may not be indicative of

high throughput. Given this disparity, it is essential that

both metrics be analyzed and compared as separate

entities.

R2-2.2 Data from rapid characterization experiments

may be displayed graphically on a Productivity

Effectiveness Plane (PEP) diagram, Figure R2-1.

R2-2.3 In PEP diagrams, IEE is plotted as a function of

throughput. Points that appear further to the right have

higher throughput and points that appear higher up have

higher IEE. It is desired to have combined equipment

and process designs whose performance would appear

in the upper right quadrant of the plane for the entire

operating range of the tool.

R2-2.4 The four experimental data points from the

sample problem are plotted in Figure R2-1 and, when

connected, appear to approximate an upward sloping

curve. This curve is referred to as a tool signature.

R2-2.5 Tool signatures may be used to describe tool

performance relative to isolated variables. This

representation helps equipment suppliers and users

visualize the effects of tool operating modes on IEE and

throughput. For more complex multi-dimensional

experiment sets, the tool signature would appear as a

hyper-surface.

R2-2.6 OEE can be plotted for comparison against tool

signatures. In Figure R2-1, an OEE measurement of a

typical week is plotted. For the known throughput

corresponding to this OEE score, the value of IEE on

the tool signature for the same throughput may be used

to approximate the IEE score for the week without

calculating IEE explicitly.

Figure R2-1

Productivity Efficiency Plane

NOTICE: SEMI makes no warranties or

representations as to the suitability of the standard set

forth herein for any particular application. The

determination of the suitability of the standard is solely

the responsibility of the user. Users are cautioned to

refer to manufacturer’s instructions, product labels,

product data sheets, and other relevant literature

respecting any materials mentioned herein. These

standards are subject to change without notice.

The user’s attention is called to the possibility that

compliance with this standard may require use of copy-

righted material or of an invention covered by patent

rights. By publication of this standard, SEMI takes no

position respecting the validity of any patent rights or

copyrights asserted in connection with any item

mentioned in this standard. Users of this standard are

expressly advised that determination of any such patent

rights or copyrights, and the risk of infringement of

such rights, are entirely their own responsibility.

Productivity Efficiency Plane [PEP]

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

010203040

Effective Unit Throughput (uph)

IEE

and

OEE

(%)

OEE

IEE

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