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SEMI E69-0298 © SEMI 1998, 2003 9 13.3 Repeat Sections 13 .2.1–13.2.6, for a total of th ree times, until at least six sets o f data have been collected at each setpoint (with th e e x ception of 100%). 13.4 Repeat Secti…

SEMI E69-0298 © SEMI 1998, 2003 8

Table 2 Test Data Cover Sheet

MFC

Manufacturer__________ Model__________ Serial Number__________ Attitude__________

Nameplate Gas__________ Seal Type__________ Valve Seat Matl.__________ Full Scale Range__________

Environment

Ambient Temp. (°C)_________ Ambient Press. (kPa)________ Humidity (%)__________

Test Gas__________ Inlet Gas Pres. (kPa)_________ Outlet Gas Press.__________ Gas Temp. (°C)__________

Test Facility

Name__________ City/State__________ Telephone ( )__________ Fax ( )__________

Standard Used__________ Standard Accuracy__________ Facility Bias__________ Certification Date__________

Other Equipment__________ Accuracy__________ Certification Date__________

Comments or Special Instructions:

Technician__________

Date__________

13.1.2 Use the cardinal setpoints and any other

setpoints of specific interest. These setpoints will be

used to determine the reproducibility of the MFC. The

setpoint increments should exceed the expected

deadband of the DUT.

13.1.3 At each setpoint under test, maintain the input

signal until the output of the DUT becomes stabilized at

its apparent final value. Observe and record the output

values in Table 1 for each input value.

13.1.4 Record five readings at each setpoint during

testing.

NOTE 2: If the data points show a trend in one direction,

either up or down, the DUT is not stable enough for the test to

proceed to the next setpoint. Record another five readings at

this setpoint. If the results continue to show a trend, repeat the

measurements at the previous setpoint. If the results are not

satisfactory at this setpoint, stop the test for this MFC. If the

results are not satisfactory, halt the test and verify the

performance of the testing apparatus.

13.1.5 At each point under test, maintain the input

signal until the output of the device under test becomes

stabilized at its apparent final value. Observe and

record the output values for each input value.

13.2 Reproducibility and Zero Drift Test

13.2.1 Apply a 50% setpoint to the MFC and record

data.

13.2.2 Move the setpoint to 100% and record data.

13.2.3 Move the setpoint to 50% and record data.

13.2.4 Move the setpoint to 10% and record data.

13.2.5 After recording data at 10%, apply a 5%

setpoint for 10 minutes, but do not record any data at

this setpoint.

13.2.6 Move the setpoint back up to 10% and record

data.

SEMI E69-0298 © SEMI 1998, 2003 9

13.3 Repeat Sections 13.2.1–13.2.6, for a total of three

times, until at least six sets of data have been collected

at each setpoint (with the exception of 100%).

13.4 Repeat Sections 13.1.1–13.3 weekly for a period

of at least 12 weeks. During the idle time, the MFC

should be continuously powered, with any exceptions

so noted. Gas flow is not required during the idle time,

but any gas flow shall be recorded. Finally, record all

details about the conditions of the MFC during the idle

time.

14 Data Analysis

14.1 Calculations

14.1.1 Determine the precision at a setpoint by

calculating the standard deviation of all the measured

values (both upscale and downscale) for that setpoint.

Perform this calculation at each setpoint:

−

)

∑

()

∑

P = Precision

The i

reading at a setpoint for a given cycle

Average measured value

umber of readings at a setpoint for a given cycle

14.1.2 Determine the short-term reproducibilty at a

setpoint by dividing the precision of the setpoint by the

average setpoint. This is expressed as a percentage of

setpoint. Perform this calculation at each point:

SRS% =

× 100

14.1.3 The long term reproducibility at a setpoint is the

greatest absolute weekly reproducibility at a setpoint.

14.1.4 Determine the precision over the test period at a

setpoint by calculating the standard deviation of all the

measured values (both upscale and downscale) for that

setpoint. Perform this calculation at each setpoint:

( V

−

)

∑

(

)

∑

( )

∑

(

)

∑

= Precision over the test period

The i

reading at a setpoint for a given cycle

Average measured

umber of readings at a setpoint for a given cycle

w =

umber of weeks

14.1.5 Determine the reproducibility at a setpoint by

dividing the precision over the test period at this

setpoint by the average setpoint. This is expressed as a

percentage of setpoint. Perform this calculation at each

setpoint:

RS% =

× 100

14.1.6 The overall reproducibility of the DUT is the

maximum value calculated in Section 14.1.4:

RD% = RS

max

RD = Reproducibility of the device

14.1.7 Calculate zero drift by subtracting the minimum

zero value from the maximum zero value and dividing

by two. This number is reported as ± sccm or slm over

the specified time period.

15 Data Presentation

15.1 Plot the average measured value of each setpoint

(10%, 50%, 100%) for each measurement period on a

graph, with the x-axis representing time, and the y-axis

showing the actual flow output in sccm or slm.

15.2 Plot the measured value at zero for each

measurement period on a graph, with the x-axis

representing time and the y-axis showing flow output

signal in sccm or slm.

15.3 Reproducibility — Report a single number, as

calculated above, as a percentage of reading stated, with

the time period of the test.

15.4 Zero Drift — Report a single number, as

calculated above, stated with the time period of the test.

16 Related Documents

16.1 SEMI

Standard

SEMI E67 — Test Method for Determining Reliability

of Mass Flow Controller (Refer to this standard if

reliability data is needed for some of the parameters

tested in this method.)

NOTICE: Unless otherwise indicated, all documents

cited shall be the latest published versions.

NOTICE: SEMI makes no warranties or

representations as to the suitability of the standards 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

copyrighted 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.

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