CN100355054C - Reliability screening method of infrared focus planardetector - Google Patents

Abstract

The present invention discloses a reliability screening method for infrared focal plane detectors, particularly a reliability screening method for electrically connecting In salient points of devices. The method adds a plurality of In salient points which are electrically connected with each other on the periphery of a photosensitive array chip, and meanwhile, a plurality of In salient points which are electrically connected with each other are arranged on the periphery of a reading circuit. After the photosensitive array chip and the reading circuit are mutually connected into a focal plane detector in a flip-chip bonding method, the additional In salient points are formed into a plurality of resistor which are communicated singly, common communication bonding points of the photosensitive array chip and the reading circuit can be used as common communication resistors, the single resistors and N common communication bonding points are connected in parallel to be formed into a test loop, measurement is carried out by a resistance tester, and the present invention can be used for the reliability screening of infrared focal plane detectors by judging measured resistance values. The present invention has the advantages of simple measurement, high testing speed, small data volume and easy realization of real-time reliability tests.

Description

The reliability screening method of infrared focal plane detector

Technical field

The present invention relates to the detection technique of infrared focal plane detector, specifically be meant the photaesthesia array chip of focus planardetector and the screening technique of the electricity soldering reliability between the reading circuit.

Background technology

Answer the active demand of infra-red thermal imaging system to detector, infrared focal plane detector obtained fast development at nearly two, 30 years.At present, infrared focal plane detector has developed into big face battle array, miniaturization, multicolor and the integrated third generation that turns to principal character.Infrared focal plane detector is made up of the responsive array chip of infrared light and its corresponding reading circuit two parts, and all realizes based on the flip-chip solder technology of indium metal (In) salient point.This welding on vertically not only will have enough mechanical strengths guaranteeing the mechanically stable between photaesthesia array chip and the reading circuit, and will guarantee that good electricity connectivity is arranged between them.

In addition, infrared focal plane detector at room temperature prepares, and its work is under the low temperature of 80-90K, so device will experience hundreds and thousands of times cold cycling.And all there is bigger thermal expansion mismatch between the silicon materials of photaesthesia detection array chip material and reading circuit usually, this can cause the fatigue damage of indium salient point under cold cycling, causes the infrared focal plane detector performance failure until not guaranteeing machinery between them and electricity to be communicated with.

Because the soldering reliability between photaesthesia array chip and the reading circuit is the key factor of restriction infrared focal plane detector rate of finished products and infrared focal plane detector reliability, so, by detecting the soldering reliability between them, just can finish the reliability screening of infrared focal plane detector.

But photaesthesia array chip and reading circuit are in case after the welding, just can not judge that directly the machinery of In salient point welding is communicated with situation by means such as metallomicroscope, scanning electron microscopy, the single electricity that can not directly measure each In salient point welding is communicated with resistance.And destructive thrust is tested, section plane test, and the focus planardetector performance test, and is not only inconvenient, and can not obtain the change information of welding performance in the failtests process in real time.

Through long-term experimental study, we find that the machinery and the electricity connectivity of welding between photaesthesia array chip and the reading circuit normally can be guaranteed.But, when infrared focus planardetector scale and area become very big, and the evenness of its photaesthesia array chip and reading circuit, or the uniformity of In bump height is poor again, and the welding performance that some position will occur does not reach requirement.These relatively poor welding performances mainly concentrate on the locational In salient point electricity connectedness all around of photaesthesia array chip and reading circuit, and it shows as excessive connection resistance.

And the thermal mismatch stress because of existing bigger thermal expansion mismatch to cause between the silicon materials of photaesthesia array chip material and reading circuit under cold cycling, its maximum are to concentrate on the welding In salient point of position around the infrared focal plane detector.So these regional In salient point fatigue damages are the main causes that cause welding performance to lose efficacy.And the notable feature that this welding performance lost efficacy is exactly, and the unexpected change of single connection resistance of In salient point welding is big.

So, as long as the single resistance that is communicated with of locational In salient point welding around directly and in real time between the responsive array chip of measuring light and the reading circuit, just can judge the welding performance situation between photaesthesia array chip and the reading circuit, to carry out the reliability screening of infrared focal plane detector.

Summary of the invention

Purpose of the present invention is exactly to provide a kind of single size that is communicated with resistance by locational In salient point welding around between the responsive array chip of measuring light and the reading circuit to judge the In salient point welding reliability screening technique of infrared focal plane detector.

To achieve these goals, reliability screening method of the present invention is as follows:

At first respectively add the In salient point of an electricity interlinkage at four angles of photaesthesia array chip, perhaps equidistantly add the In salient point of several electricity interlinkages again at each periphery, on reading circuit, also add the In salient point of the electricity interlinkage corresponding simultaneously with the photaesthesia array chip, the In salient point of these interpolations can be made when preparation photaesthesia array chip and reading circuit in passing, can not increase device preparation technology step and complexity.

Behind photaesthesia array chip and focus planardetector of reading circuit inverse bonding interconnection formation, after the corresponding one by one interconnection of the In salient point that adds between photaesthesia array chip and the reading circuit, just constitute several single connection resistance, and the public connection pad of photaesthesia array chip and reading circuit can be seen public connection resistance as, again with several single connection resistance and test loop of N public connection pad formation in parallel, measure with resistance meter, utilize equation:

$R_C=R_1+\frac{R_2}{N}\&ap;{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C20051003079400091.png"\; state="\{\{state\}\}">R</figure-callout>}}_1,N\&GreaterEqual;100$

Carry out the judgement of In salient point electricity connectedness, work as R _CSuddenly increase, illustrate that the In salient point electricity of device is communicated with problem, performance is unreliable.In the formula, R _CBe the single connection resistance that the approximate In salient point that records welds, R ₁Be the single connection resistance of real In salient point welding, R ₂Be public connection resistance, N is the number of public connection resistance.When the number N of public connection welding was enough big, following formula is establishment just, i.e. R _CBe approximately equal to R ₁

Usually the number of the public connection welding of infrared focal plane detector can both satisfy above-mentioned requirements.So,, just can be used for the screening of infrared focal plane detector reliability as long as test the single connection resistance of focus planardetector In salient point welding all around one by one.

Advantage of the present invention is:

1. the In salient point of the present invention's interpolation is to make in passing in the device preparation process, can not bring any difficulty to preparation technology.

2. the present invention just can make things convenient for, carry out reliably the screening of infrared focal plane detector reliability by measuring the infrared focal plane detector single connection resistance of the In salient point welding of position all around.

3. owing to be that the single welding of position is communicated with resistance around the direct measuring element,, improved the accuracy of screening so can avoid the interference of focus planardetector photaesthesia signal in testing process.

4. the present invention only need be concerned about the In salient point of position around the infrared focal plane detector, the single connection resistance information of four locational In salient point welding in angle particularly, so the speed that detects is very fast, data volume is also less, is easy to realize that reliability detects in real time.

Description of drawings

Fig. 1 is the structural representation of photaesthesia array chip of the present invention and reading circuit;

Fig. 2 is an electrical testing loop structure schematic diagram of the present invention;

The single connection resistance situation that Fig. 3 records for present embodiment is (a) for just having prepared the connection resistance value that device records, (b) for impact the connection resistance value that records after 100 times through liquid nitrogen.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is elaborated:

The present invention is embodiment with the HgCdTe infrared focal plane detector, and the area of the infrared photosensitive first array chip 4 of the HgCdTe of GaAs substrate is 4 * 6mm ², the pedestal area of Si base reading circuit 5 is 6 * 9mm ²When the design device, 40 In salient points around photosensitive first array chip, have equidistantly been added, simultaneously also correspondingly around Si base reading circuit 40 In salient points have been added, the In salient point of these interpolations can be made when preparation photaesthesia array chip and reading circuit in passing, can not increase device preparing process step and complexity.After photaesthesia array chip and reading circuit inverse bonding interconnection, just constitute 40 single connection resistance 2 at its In salient point that adds all around, public connection pad directly adopts the public connection electrode 3 of device to obtain, and has the In salient point pad of 200 parallel connections.Therefore, it can utilize equation:

$R_C=R_1+\frac{R_2}{N}\&ap;{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C20051003079400091.png"\; state="\{\{state\}\}">R</figure-callout>}}_1,N\&GreaterEqual;100,$

Measure, in the formula, R _CBe the single connection resistance that the approximate In salient point that records welds, R ₁Be the single connection resistance that the real In salient point that adds welds, R ₂Public connection electrode by device obtains, and N is the number of public connection resistance.

The measurement of single connection resistance is to finish on the I-V test macro 1 of Keithley (Keithley company) 4200 types.During measurement, adopt the I-V test in small voltage source, voltage range be-0.5V is to+0.5V, and sweep spacing is 0.005V, and direct read test resistance partly.

See Fig. 3, test result shows that the single connection resistance of In salient point welding is about several ohms, and size is more even, and it is little to impact 100 variations later at liquid nitrogen.Simultaneously, carry out the test of focus planardetector performance, find that they do not have significant change in 100 front and back of liquid nitrogen impact yet.The technical scheme that this explanation adopts the single connection resistance information around the focus planardetector to detect in real time, it is rational, feasible carrying out focus planardetector reliability screening.

Claims (2)

1. the reliability screening method of an infrared focal plane detector is characterized in that concrete steps are as follows:

A. at first respectively add the In salient point of an electricity interlinkage, on reading circuit, also add the In salient point of the electricity interlinkage corresponding simultaneously with the photaesthesia array chip at four angles of photaesthesia array chip;

B. behind photaesthesia array chip and focus planardetector of reading circuit inverse bonding interconnection formation, after the corresponding one by one interconnection of the In salient point that adds between photaesthesia array chip and the reading circuit, just constitute four single connection resistance, and the public connection pad of photaesthesia array chip and reading circuit can be seen public connection resistance as, again with four single connection resistance and test loop of N public connection pad formation in parallel, carry out single connection resistance measurement with resistance meter, utilize equation:

$R_C=R_1+\frac{R_2}{N}\&ap;R_1,$ N≥100

Carry out the judgement of In salient point electricity connectedness, work as R _CSuddenly increase, illustrate that the In salient point electricity of device is communicated with problem, performance is unreliable;

In the following formula, R _CBe the single connection resistance that the approximate In salient point that records welds, R ₁Be the single connection resistance of real In salient point welding, R ₂Be public connection resistance, N is the number of public connection resistance.

2. the reliability screening method of an infrared focal plane detector is characterized in that concrete steps are as follows:

A. at first add the In salient point of an electricity interlinkage at four angles of photaesthesia array chip, equidistantly add the In salient point of several electricity interlinkages again at each periphery, on reading circuit, also add the In salient point of the electricity interlinkage corresponding simultaneously with the photaesthesia array chip;

B. behind photaesthesia array chip and focus planardetector of reading circuit inverse bonding interconnection formation, after the corresponding one by one interconnection of the In salient point that adds between photaesthesia array chip and the reading circuit, just constitute several single connection resistance, and the public connection pad of photaesthesia array chip and reading circuit can be seen public connection resistance as, again with several single connection resistance and test loop of N public connection pad formation in parallel, carry out single connection resistance measurement with resistance meter, utilize equation:

$R_C=R_1+\frac{R_2}{N}\&ap;R_1,$ N≥100

Carry out the judgement of In salient point electricity connectedness, work as R _CSuddenly increase, illustrate that the In salient point electricity of device is communicated with problem, performance is unreliable;

In the following formula, R _CBe the single connection resistance that the approximate In salient point that records welds, R ₁Be the single connection resistance of real In salient point welding, R ₂Be public connection resistance, N is the number of public connection resistance.

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