IC Testing Pragya Kushwaha KIT S2

8/3/2019 IC Testing Pragya Kushwaha KIT S2

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Session 2Session Name: IC Testing

Author Name: Pragya Kushwaha

Department: Electronics and Communication

Subject/Course: VLSI Design


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Page 2 Ver : 1.01 IC TestingPragya Kushwaha, Kanpur Institute of Technology

Session Objectives

At the end of this session, the learner will be able to:

Discuss the need for IC Testing.

List and explain the various IC Faults.

Discuss the steps in testing an IC.

Explain the test pattern generation.

Teaching Learning Material

Board.

Presentation Slides.LCD Projector.


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IC Testing Page 3Pragya Kushwaha, Kanpur Institute of Technology

Session Plan

Time(in

min)Content Learning Aid and

MethodologyFaculty

Approach

TypicalStudentActivity

Learning Outcomes(Blooms + Gardeners)

15 Need for IC TestingAnalogy

Chalk and Talk

ConductsFacilitatesDebriefs

ParticipatesAnswers

Comprehends

RememberingUnderstandingIntrapersonalInterpersonal

Linguistic

15 Types of IC FaultsSlide

PresentationChalk and Talk

ExplainsListens

ObservesComprehends

RememberingUnderstandingIntrapersonal

Visual

10 IC Testing Steps

VideoSlide

PresentationChalk and Talk

ExplainsFacilitates

ListensObserves

Comprehends


Visual

10Test PatternGeneration

SlidePresentation

Chalk and Talk

ExplainsFacilitates

ListensObserves

Comprehends


LogicalMathematical

Visual

10 Conclusion Pictorial QuizConducts

Facilitates

Questions

DiscussesRecalls

Answers


InterpersonalVisualLinguistic


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Session Inputs

Need for IC Testing

We can begin the session on IC testing by explaining an analogy to

the learners and by comparing the same with the IC Testing.

Through this, we can explain the need for IC Testing to our learners.

Suggested Activity: Analogy

Let us make learners understand the need for an IC testing through the

following analogy.

Ram and Sanjay are good friends. Suppose if a teacher wants to find out whois intelligent and who is stupid amongst them according to the strategic plan,

then, the easy way to solve this problem is Exam Test.

Suppose if Ram passes the exam, then it is sure that, Ram knows the strategy

to work.

On the other hand if Sanjay fails in the exam, then it means that, Sanjay has

not worked accordingly.


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Finally, we can ask the learners to list out their inference from the analogy and

we can conclude the following:

We learnt two things from this example:

Student who works according to strategic plan will PASS in the exam.

Student who does not work according to the strategy will FAIL in the exam.

Similarly, a good IC will PASS the IC Test and on the other hand a faulty IC will

not PASS the IC test.

Good IC is like a brilliant student who passes every exam. Hence

good is an IC which has no fault at any level of its formation.

Faulty IC is like a failed student who is not able to pass the exam.

Types of IC Faults

Having explained the need for an IC testing, let us now discuss theIC faults by showing some pictures on presentation slides to the

learners.

Here Figure 1 is showing Physical Defects developed in IC during the

time of fabrication.

Types of physical defects are:

Defects in silicon substrate, Photolithographic defects, Mask

contamination and scratches, Process variations and abnormalities,

Oxide defects.


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Figure1: Physical Fault

There are many process of IC formation after their completion we

get our fully working IC. But as IC goes through these processessome kind of unwanted electrical connections occurs that creates

IC failure during IC testing.

These electrical faults are:

Shorts (bridging faults), Opens, Transistors stuck-on, stuck-open,

Resistive shorts and opens, Excessive change in threshold voltage,

Excessive steady-state currents. This is shown in figure 2 below.

Figure2: Electrical Fault

Logical fault occurs when logic of gate stuck at any logic 0 or 1.

Examples of logical faults are: Logical stuck-at-0 or stuck-at-1, Slower

transition (delay faults), AND-bridging, OR-bridging. This is shown in


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figure 3 below.

Figure3: Logical Faults

Fabrication faults occur during the fabrication time.

Electrical faults are like shorted resistances and open circuited

resistance.

Logical faults are the faults which are logically not correct.

IC Testing Steps

With the help of a video clip, the IC Testing steps can be discussed.

The following link contains a video file that shows a tester used to

test the working condition of an IC.

http://www.mission10x.com/mission-

10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2

A tester is the one, on which we can insert the device (IC) under

test. The tester in the video shows some kind of test pattern to check

the programs inside it. When IC passes all those in built test patterns,

we get output: IC PASS, it means that, our IC can be used further for

any kind of circuit formation.

When IC is not able to pass any of those in built test patterns, we getoutput: IC FAIL, it means that, our IC is faulty and hence we cant

use it further for any kind of circuit formation. And in this way we can

save our overall system testing cost.

Auto mode and Manual mode are there in tester for testing our

IC.
http://www.mission10x.com/mission-10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2http://www.mission10x.com/mission-10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2http://www.mission10x.com/mission-10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2http://www.mission10x.com/mission-10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2http://www.mission10x.com/mission-10x/Documents/IC%20TESTING%20VIDEO_PRAGYA_S2


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IC will pass the electrical test when it follows test patterns.

Test Pattern Generation

Let us now proceed with the test pattern generation by explaining

fault models using the slide presentation. We can give various

pattern generation problems to our learners so that they can get

better understanding of IC faults.

As we can see in this flow chart below, first we will have to find

which type of fault our IC has? Further accordingly we can

generate the test pattern to test our IC.

Test Pattern Generation and Fault

Simulation

Output of gate 1 is stuck-at logic zero (s-a-0). The faults are

activated by applying logic 1 at the inputs of gate 1.

Input test pattern for this fault is (A,B,C,D,E,F,G) (1,0,1,0,0,1,0).

Output 1 in the fault-free case, or Output 0 if the fault exists.

Now, we can find type of fault and then generate test pattern for

IC.


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Conclusion

Finally, we can conclude the session by revising the key points

discussed so far, through the following Pictorial Quiz activity.

Suggested Activity: Pictorial Quiz

To begin with this activity, the learners can be divided into two groups

(columns wise). We can select one representative from each group. The

group members can collectively help their team representative to identify the

keyword written on the power point slide by giving clues in the form of its

definition, function, etc. If he/she identifies the keyword correctly, one point

can be given to the group. The group with highest point can be declared as

winners.

The following are some sample questions based on pictures:

1. Why IC Testing is important?

The possible answer:


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Debugging cost will become high if whole system will fail, so we have to test

our IC at each level.

2. See the figure and tell four major level of IC testing.


Component Test, Package Test, Board Electrical Test, System Reliability Test

3. See the figure and tell? How much factor of cost will IC testing take incomparison to IC Designing?


45% of the total cost.

Click the below link to view the PPT for some more sample questions.


10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppt
http://www.mission10x.com/mission-10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing_Pictorial%20Quiz_Pragya_KIT.ppt


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Click the following link to view the PPT on IC testing for more

detailed explanation of the concepts covered so far.


10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppt
http://www.mission10x.com/mission-10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppthttp://www.mission10x.com/mission-10x/Documents/IC%20Testing%20PPT_Pragya_KIT.ppt


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Summary

In this session, we learnt to:

Discuss the need for IC Testing.

List and explain the various IC Faults.

Discuss the steps in testing an IC.

Explain the test pattern generation.


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Assignment

Find some more videos on IC testing and present them in group.

Do some numerical on test pattern generation by finding fault type in IC.


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References

www.youtube.com/watch?v=z1sRk5PYLCw

www.youtube.com/watch?v=YrF99bQ44Wc
http://www.youtube.com/watch?v=z1sRk5PYLCwhttp://www.youtube.com/watch?v=z1sRk5PYLCwhttp://www.youtube.com/watch?v=YrF99bQ44Wchttp://www.youtube.com/watch?v=YrF99bQ44Wchttp://www.youtube.com/watch?v=YrF99bQ44Wchttp://www.youtube.com/watch?v=z1sRk5PYLCw

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