semi合集-English.pdf - 第6478页

SEMI G78-0699 © SE MI 1999 11 From the last die of wafer 10 until the wa fer is stored in the wafer boat and the boat is free t o be rem ove d from the prober (LDT2C ) Start Stopwatch, pr ober From pushin g "star t&…

SEMI G78-0699 © SEMI 1999 10

9.5 Probe Card Condition — a me trology tool

printout verifying the ‘x’, ‘y’ and ‘z’ position of each

probe is within the users specification must accompany

the probe card.

9.6 Tester – Prober Communications — The type of

communications method used between the prober and

the tester is left up to the user of this test method.

Because communication overhead varies with protocol,

the same hardware and “test program” (modified as

necessary to communicate to the prober under test)

must be used for all tests.

9.7 Presence of the PTI — During the test, the probe

card must have loading similar to that applied by the

normal “in use” application such as a Probe Test

Interface (PTI) or Direct Docking Pogo Stack. The

force exerted on the probe card by the PTI will stabilize

the probe card, improving the repeatability of the data

collected.

9.8 Wafer Cassette — For the purp oses of these tests,

a cassette of wafers is defined as containing ten wafers.

Ensure the wafers are placed in the same slots for each

test.

10 Test Procedure (see Figur es 8 and 9)

10.1 Load wafer cassette

10.2 Install probe card

10.3 Set probe mode to serpentine, set all other

necessary prober parameters. N

OTE THAT ALL DIE ON

ALL WAFERS ARE TO BE “TESTED”, NOT JUST THE 12 DIE

FROM WHICH PROBE MARK DATA WILL BE ANALYZED.

10.4 Note all applicable parameters (see chart below)

10.5 If temperature testing, soak for a user-defined

time (consistent with the user’s test methodologies) that

is equal on all corresponding tests on all probers being

evaluated.

10.6 Start probing process and stop watch

simultaneously.

10.7 The “test program” must perform automatic

alignment of the probe card to the wafer prior to wafer

#’s 1, 2, 5, and 8.

NOTE: While not required, it is recommended that the PTI

and Probe Card be removed and re-installed prior to each of

the automatic alignment steps to simulate whatever locational

error might be induced by manipulation of the interface and

the probe card.

10.8 Record times of individual eve nts (utilizing the

stopwatch’s “split” function) on the supplied chart or a

similar form.

10.9 When the last wafer is finished and has been

returned to wafer cassette, stop the stopwatch.

10.10 Collect the probe mark offset data from wafers.

10.11 Calculate Normalized (by lot) Die Offset

[Accuracy] and 3σ of Normalized (by lot) Die Offset

[Repeatability]:

Place boat of

wafers in wafe

handler

Install probe card

If test environment

is "overhead",

install PTI and/or

dock test head

Set up prober for

test

This

procedure

will var

depending

upon the

prober type

being used,

the wafer

layout, and

many other

variables.

Document all

prober settings

If testing at other

than ambient

temperature, pre-

soak

10.1 10.2

10.7

10.3 10.4 10.5

Figure 8

Setup

SEMI G78-0699 © SEMI 199911

From the last die

of wafer 10 until

the wafer is stored

in the wafer boat

and the boat is

free to be removed

from the prober

(LDT2C)

Start Stopwatch,

prober

From pushing

"start" to the

testing of the first

die on the first

wafe

(

S2FDT

OCR

)

From beginning to

end of automatic

probe-to-pad

alignment

procedure

Note that this

procedure is to be

performed prior to

wafers 1,2,5 & 8

Using the stopwatch's

"split" function, record

the following times:

APTPA

PTPA

From pushing

"start" to the

testing of the first

die on the second

wafer

(S2FDTW2)

From the last die

of wafer 3 to the

first die of wafer 4

(A2B)

Stop stopwatch at

this time

(TTCC)

1 2 3 4 5 6 7 8 9 10

10.6

10.7

10.9

Figure 9

Timing Procedure

11 Introduction

11.1 The Probe Mark Analysis System recognizes the edge of the bond pad passivation opening and the probe

mark, draws a best-fit rectangle around the probe mark and passivation opening, and returns the four distances, Left,

Right, Bottom and Top to a text file. The center position of the best-fit rectangle can be used to represent the center

of the scrub mark. An offset of this center of scrub mark from the center of the bond pad can be calculated as

follows:

2/)(

TopBottomPadYoffset

RightLeftPadXoffset

−=

(1)

The variation of this offset from pad to pad, die to die, wafer to wafer and setup to setup captures most of the

process variations.

11.2

PMA Data Analysis

11.2.1 We will use a sampling scheme of 9 wafers per lot, (3 setups per lot, 3 wafers per setup), 12 dies per wafer

and 24 pads per die as an example for discussing the data analysis algorithm. The first step of doing data analysis is

to obtain the offsets for all the pads that have been sampled using Eqn.(1). This means that the offsets

yoff

xoff

padmdielwafksetjloti

t][PadYoffse

t][PadXoffse

,,,,

(2)

for a pad m on die l, wafer k, under setup j in lot i are known.

Step 1

Calculate Average Die Offset for the lot [LOTX or LOTY] (3)

,,,,,,,

padmdielwafksetjlotidielwafksetjloti

yoffyoff

xoffxoff

(3)

Step 2

Calculate D-D-X or D-D-Y = 3σ of Average Die Offset [LOTX] and [LOTY](3)

These die offsets are again treated on the equal basis. A 3σ value is calculated and becomes our Die-to-Die

Variation (D-D-X, D-D-Y) for the entire lot.

LOTX + D-D-X, LOTX - D-D-X = Total Prober X-Error Range (3σ)

LOTY + D-D-Y, LOTY - D-D-Y = Total Prober Y-Error Range (3σ)

Suggested Graphs for X-Offset and Y-Offset (see Appendix 1 for examples):

X-Offset Y-Offset

LOTX + D-D-X LOTY + D-D-Y

LOTX LOTY

LOTX - D-D-X LOTY - D-D-Y

Average Die X-Offset (3) Average Die Y-Offset (3)

12 Data Collection Table

12.1 The following data are to be recorded about the test environment:

Title Description Values

Installed (Yes/No)

Tester - Prober Interface

If installed, Total Pogo

pin force (nominal, calculated)

pounds

Present [docked] (Yes/No)Tester

If present, state manufacturer and

model

Wafer Nominal Die Size (Small, Medium

or Large)

Needle count

gramsNominal force per needle

ounces

micronsDiameter of needle tip

mils

micronsNeedle pitch (within a single row or

column)

mils

Number of needle tiers

Size of needle array in the X

direction (left-to-right when facing

prober (from the operator position))

inches

mmSize of needle array in the Y

direction (away and towards the

operator relative to the center of the

probe card)

inches

Probe Card

Diameter of probe card

inches

ºCSet point / Temperature of chuck

during test

ºF

Soak time, probe card (if test

temperature is other than ambient)

minutes

Test Temperature

Soak time, prober (if other than

ambient)

minutes