IPC-TM-650 EN 2022 试验方法.pdf - 第306页

1.0 Scope This test method establishes a procedure for determining the flatness of silicon wafers coated with depos- ited organic films. 2.0 Applicable Documents ASTM D 618 Standard Practice for Conditioning Plastics and…

5.3

Calculation of Results

5.3.1 Average Bow and Twist Results

Bow and Twist =

Sum of the Measured Maximum

Vertical Displacements in mm [in]

Number

of Test Specimens

5.3.2

Maximum Bow and Twist Results

The

maximum

vertical displacement in mm [in] obtained for each lot of

material.

6.0 Notes

6.1

This

is the referee method; other methods of measure-

ment are allowable, if agreed upon between user and vendor.

IPC-TM-650

Number

2.4.22.1

Subject

Bow

and Twist—Laminate

Date

5/93

Revision

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1.0

Scope

This

test method establishes a procedure for

determining the flatness of silicon wafers coated with depos-

ited organic films.

2.0

Applicable Documents

ASTM D 618

Standard

Practice for Conditioning Plastics and

Electrical Insulating Materials for Testing

3.0

Test Specimen

The

test specimens are 125 mm diam-

eter silicon wafers 625 ± 15 µm in thickness. The surface of

the wafers must be clean, and at least one side of the wafers

must be polished. A minimum of 9 wafers are required.

4.0

Apparatus or Material

4.1 Radius Of Curvature Measurement Device

Flexus

Thin

Film Stress Measuring Apparatus (TFSMA) Model 2-300

or equivalent.

4.2

Wafer Thickness Measurement Device

Micrometer

capable

of measuring accurately to 5 µm. A thickness gauge

including weights can also be purchased from Flexus that can

be used with the TFSMA to measure thickness.

4.3

Film Thickness Measurement Device

Nanospec

Model

210, Tencor AlphaStep, or equivalent film thickness

measurement device capable of measuring accurately to 0.1

µm.

5.0

Procedure

5.1 Radius Of Curvature Of Uncoated Wafers

5.1.1

Label

each wafer with a unique identification.

5.1.2

Measure

the thickness of the uncoated silicon wafers.

5.1.3

Measure

the radius of curvature of the uncoated

wafers following the manufacturers recommended procedure.

5.2

Coat Wafers

5.2.1

Use

a minimum of three film thicknesses for each

polymer or processing condition investigated. The film thick-

nesses should span as large a range as possible, e.g., 5, 10

and 15 µm. Coat at least three wafers for each film thickness

for a minimum of nine wafers.

5.2.2 Coat

the polymer solution onto the back (unpolished

side) of the silicon wafers using manufacturer s recommended

deposition technique (e.g., spin coating). Process the coating

according to the manufacturer s recommended procedures.

The final film thickness must not vary by more than 2% across

the substrate surface.

5.3

Radius of Curvature Of Coated Wafers

5.3.1

The

coated wafers should be conditioned at 23 ± 2°C

and 50 ± 5% relative humidity for exactly 24 hours prior to

testing. Many polymers exhibit stress relaxation or a decrease

in stress associated with moisture absorption, therefore it is

essential that the coated wafers are equilibrated under identi-

cal conditions. Refer to ASTM D 618.

5.3.2

Measure

the radius of curvature of the coated wafers

following the equipment manufacturer’s recommended proce-

dure. Correct placement of the wafers in the device is essen-

tial to compensate for nonuniform wafers, therefore the wafer

must be placed in the same position for each measurement.

At this point the coating thickness is unknown; however,

some value may be required by the curvature measurement

device. Use whatever number is convenient for now, the data

will be edited later.

5.3.3

Repeat

step 5.3.1 four (4) times for each wafer. The

reason for the repeated measurements is to generate an aver-

age to compensate for errors in placing the wafer in the cur-

vature measurement device at the exact position in which it

was originally measured during step 5.1.3.

5.4

Film Thickness Measurements

Measure

the film

thickness on each coated wafer to an accuracy of 0.1 µmor

better using the film thickness measurement device. The

thickness should be measured at several different locations to

compensate for nonuniform coatings.

5.7

Calculations

The

Institute for Interconnecting and Packaging Electronic Circuits

2215 Sanders Road • Northbrook, IL 60062-6135

IPC-TM-650

TEST

METHODS MANUAL

Number

2.4.22.2

Subject

Substrate

Curvature: Silicon Wafers with Deposited

Dielectrics

Date

7/95

Revision

Originating Task Group

Deposited Dielectric Task Group (C-13a)

Material

in this Test Methods Manual was voluntarily established by Technical Committees of the IPC. This material is advisory only

and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this

material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.

Equipment referenced is for the convenience of the user and does not imply endorsement by the IPC.

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5.7.1

Calculate

the average effective radius of curvature and

the standard deviation for each wafer from the 4 measure-

ments made on each wafer in step 5.3.2 using the following

equation:

R =

)

− R

)

where

R1 and R2 are the radius of curvature of the uncoated

and coated wafers respectively. The standard deviation is cal-

culated as follows and reported to two significant figures:

√

i = 1

−

(

i = 1

)

N(N−1)

where

the value of a single observation (i = 1 through N),

N is the number of observations and s

the estimated stan-

dard deviation.

5.7.3

Calculate

the average effective radius of curvature for

each film thickness using the averages from step 5.7.1 of all

three wafers at the same film thickness. Do not include in the

calculation the data from any wafer for which the standard

deviation from 5.7.1 is greater than 10%.

5.7.4

Convert

the average effective radius of curvature for

each film thickness from step 5.7.3 into the wafer deforma-

tion, h, using the following equation

h = R

−

√

−

where

L is the diameter of the wafer and R

the average

effective radius of curvature obtained in 5.7.3.

5.7.5

Curvature Slope

The

wafer deformation values for

each film thickness from step 5.7.4 are plotted as wafer defor-

mation (y-axis) versus film thickness (x-axis). An equation of

theformy=mx(i.e. a straight line with intercept atx=0,y=

0) is fit to the data (unweighted) and the slope of the line can

be used to compare different materials or processes when

coated on identical substrates. A typical plot is illustrated in

Figure 1.

6.0 Notes

6.1

The

Flexus determines the radius of curvature by shining

a He-Ne laser beam through a beam splitter. The two beams

are reflected off the surface of the wafer into detectors. The

radius of curvature, R, is calculated from the angle of reflec-

tion and the distance between the two beams. If measure-

ments are made on the coated side of the wafer, the laser

beam is refracted twice, once upon entering the polymer layer

and again upon exiting the polymer layer. As the polymer layer

increases in thickness, the refracted laser beam can no longer

be correctly detected by the detector, resulting in erroneous

values for the radius of curvature. In practice, the upper limit

on thickness for polyimides was found to be approximately

10-12 µm. To avoid this complication, the polymer films are

deposited on the back of the wafers and the measurements

are made on the front (polished side) of the wafer. This

extends the useful thickness range to 50 µm.

6.2

The

radius of curvature will depend on the thickness of

the wafer. Wafers of comparable thickness (625 ± 15 µm)

must be used when making comparisons of different

materials.

2.4.22.2−01

Figure

Film Thickness (µm)

Curvature

Slope = 3.3

Wafer Deformation (

048

121620

IPC-TM-650

Number

2.4.22.2

Subject

Substrate

Curvature: Silicon Wafers with Deposited Dielectrics

Date

7/95

Revision

age2of2

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