Study of damage and stress induced by backgrinding in Si wafers

Chen, Jian; Wolf, Ingrid De

doi:10.1088/0268-1242/18/4/311

Cited by 102 publications

(48 citation statements)

References 3 publications

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“…This level of strain generates a 5 MPa stress for the elastic modulus measured. The corresponding deflection can be roughly estimated using Stoney's equation [27,28] r Et 2…”

mentioning

confidence: 99%

Polymer–Silicon Flexible Structures for Fast Chemical Vapor Detection

et al. 2007

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Although there are several aspects that contribute to an efficient chemical sensor system, the choice of responsive materials can help to optimize several key attributes critical for their ultimate performance, specifically high sensitivity, selectivity, fast response time, and wide dynamic range. Some common issues reported to date for sensors are limited detection range, slow response time, long recovery period, and fast saturation (limited dynamic range).[1] Most of these issues are directly related to the large volume of bulk porous material that is needed for measurable signal output, which leads to inherently slow sorption, diffusion, and desorption processes. One type of gas sensor that receives only limited attention despite being among the most frequently used sensors for measuring important environmental quantities is the humidity sensor.[2]Important applications of this type of sensor include for respiratory equipment, incubators, chemical gas purification, and surgical operations. The main requirements for humidity sensors are good sensitivity over a wide humidity range, low hysteresis, good reproducibility, and longevity. [2,3] Often sensors are required to be very small and suitable for integration into arrayed systems, such as odor-sensing arrays. Humidity sensors currently tend to exploit the characteristics of bulk materials with the required resistive and capacitive response properties. This type of sensor comprises a moisture sensitive ceramic, metal, or polymer material that undergoes changes in resistance or capacitance with variations in ambient humidity. [3,4] Water vapor sensors that use polymeric materials commonly incorporate polyimides, polycarbonates, cellulose acetates, or conductive polymers. [5,6] The typical vapor sensitivity of such sensors is of the order of tens of parts per million (or ±0.05 % relative humidity, RH), which is sufficient for most routine measurements. However, this is not acceptable if a fast, real-time monitoring of vapor content variation is required. Increased sensitivity, to a low ppm level, can be achieved using a porous material to maximize the specific surface area available for water vapor adsorption. [7][8][9] For example, 0.4 ppm v (parts per million by volume) water vapor detection was demonstrated by Salonen et al. using carbonized porous silicon.[9] Bruno et al. used a polymer-coated resonant device to obtain a sensitivity of 7 ppm v .[10] In these cases, although the sensors reported showed good sensitivity they suffered sluggish response times, often requiring a few minutes to completely recover. Currently, modest sensitivity and slow response are the main obstacles to the design and development of microcantilever-based sensor technology. [11,12] In this Communication, we present a bimaterial design for humidity sensing with a vapor-sensitive plasma-polymerized nanolayer coating on a silicon microcantilever with a low flexural rigidity (Fig. 1a,d). The coating acts as a sensitive mechanical actuator, which mediates high internal stresses, enabling...

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“…This level of strain generates a 5 MPa stress for the elastic modulus measured. The corresponding deflection can be roughly estimated using Stoney's equation [27,28] r Et 2…”

mentioning

confidence: 99%

Polymer–Silicon Flexible Structures for Fast Chemical Vapor Detection

et al. 2007

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“…However, as shown in Figure 5b, the differences in the estimation differences may be attributed to a 3PB bending moment that is not aligned with the crucial assumption of Stoney's formula, where film stresses and the associated system curvatures are non-uniformly distributed over the test specimen area [38]. Moreover, the variations of the silicon thickness on the displacement loading and micro-defect on the actual silicon surfaces may also contribute to the potential differences [26]. Hence, the appropriate SBS estimation of a silicon should be accomplished with a lab scale test but Stoney's formula can be utilised for a thin film stress for a possible wafer warpage stress.…”

Section: Influence Of Silicon Thicknesses On Sbsmentioning

confidence: 97%

“…Although the damaged layer is not a real thin film, it is assumed as a thin layer and its stress can be calculated, where E / (1 -ν) is the biaxial modulus of the substrate, h is the substrate thickness, t is the film thickness, and R is the radius of the curvature. This analytical estimation will be compared to the experimental data to check on the sensitivity of the available lab scale test data, which is also being explored by [26], before analysing the bending stress from the curvature of a silicon wafer. by [27].…”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation on the silicon mechanical performance of electronic packaging

Fong¹,

Koay²,

Azid³

2017

J. MECH. ENG. SCI.

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Semiconductor packaging is trending towards a miniaturisation in size but an increase in functionality. Hence, the thickness of the silicon wafer has decreased dramatically with a concern on the possible degradation of the strength of the thinned wafer. In this paper, 3-point bend (3PB) on bare silicon is selected as the preferred silicon break strength (SBS) test methodology due to its setup effectiveness and subsequent application in the prediction study. This experimental testing study focused on evaluating the SBS from different thickness ranges. The study was then followed by evaluating the influence of a possible impact from flaw creation with laser marking on silicon surfaces. The results show that the SBS is consistent although with significant differences in the silicon thickness ranges. It is also revealed that the onset breaking load may not be a suitable metric and could be over sensitive on gauging the SBS comparison. The flaw creation from the engraving process revealed a significant drop of 75% SBS although with an approximate depth removal of <10% from the total thickness. The consistence failure mode is clearly visible and this left the silicon very vulnerable to catastrophic failure. This indicates that extra care is needed on ultra-thin silicon during the assembly process as fractures may happen even before any reliability stress test is conducted. Furthermore, the completion of the package level 3PB failure mode verification has helped to demonstrate that an SBS study can be conducted with a simplified bare silicon level testing. In short, the study with this simplified 3PB has successfully proven its usefulness in SBS estimation. The observed ultra-thin silicon SBS has degraded and strongly depended on the critical flaws especially from the surface defect and impact from the assembly handling.

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“…Die strength of the thinned wafer can be evaluated by using the different mechanical testing techniques such as three point bend test, four point bend test, ball on ring test, ball breaker tests and ring-on-ring tests. The mechanical tests are greatly influenced by several processes and material parameters such as surface roughness or finish, degree of thinning, stress relief process, quality of the dicing edge [11][12][13][14][15]. However the literature available related to the effect of grinding processes on the active side of the die/chip is limited, and this necessitates a focused study on the effect of wafer back grinding on the active side of chip.…”

Section: Low-k Dielectric Materials For Beol (Back End Of the Line) Mmentioning

confidence: 99%

Mechanical Characterization of Black Diamond (Low-k) Structures for 3D Integrated Circuit and Packaging Applications

Sekhar¹

2012

Nanoindentation in Materials Science

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Study of damage and stress induced by backgrinding in Si wafers

Cited by 102 publications

References 3 publications

Polymer–Silicon Flexible Structures for Fast Chemical Vapor Detection

Polymer–Silicon Flexible Structures for Fast Chemical Vapor Detection

Experimental evaluation on the silicon mechanical performance of electronic packaging

Mechanical Characterization of Black Diamond (Low-k) Structures for 3D Integrated Circuit and Packaging Applications

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