Die separation and rupture strength for deep reactive ion etched silicon wafers

Porter, Daniel; Berfield, Thomas A.

doi:10.1088/0960-1317/23/8/085020

Cited by 12 publications

(10 citation statements)

References 18 publications

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“…In this example, the plasma-based technique is nearly an order of magnitude more resistant to fracture than dies produced with a mechanical saw, and about three times stronger than those made with a stealth-based laser technique. Porter and Berfield also report improved die strength with the plasma approach compared to traditional mechanical saw [5]. The absence of cracking and chipping in plasma etched die can be seen in the images presented in Figure 7.…”

Section: D: Enhanced Die Fracture Strengthmentioning

confidence: 83%

Wafer Dicing Using Dry Etching on Standard Tapes and Frames

Lishan

Lazerand

Mackenzie

et al. 2014

International Symposium on Microelectronics

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To meet the changing demands of consumer product form factors, there has been a steady shift to thinner and smaller semiconductor die, both of which increase the challenges for die singulation. The traditional approach of saw dicing is facing new limitations due to die damage and throughput. Compounding these issues is the finite width of saw blades, saw blade loading from clearing multiple materials, and orthogonal layout restrictions. Laser dicing has been introduced to address some of these issues, but faces other limitations such as damage from the heat affected zone, ablation residues, throughput, and material incompatibilities (changes in transparency and absorption in the street). In some cases, a combination of both saw and laser has been utilized to surmount some of the technical obstacles. The recently introduced approach of front-side plasma singulation circumvents many of the limitations of saws and lasers. The technology presented in this work uses standard dicing tape and frames, is through-wafer complete die separation, and does not involve a subsequent wafer thinning or die cleaving step. Our approach utilizes lithographically defined singulation lines with typical widths of 10–15μm, and delivers chip/crack-free edges with low-stress rounded corners. The parallel nature of this singulation method enables non-orthogonal and non-linear singulation streets allowing die layout and design flexibility not achievable by saws and/or lasers. As a consequence, plasma singulation produces increased good die per wafer through better wafer area utilization, lower die failure (reduced corner stress with rounded geometry), and flexibility in die placement near wafer edge on larger die. One of the unique advantages is that this technology can be implemented without addition of any new masking layers but instead the use of the existing passivation, metals and/or upper dielectrics as masks. Implementing this technology across a wide range of die applications such as power, memory, logic, imaging sensors, LEDs, and MEMS must address a diverse range of variables such as compatible materials, bond pads/bumps, and backmetal. For dies with backside metal, a non-etch based method to allow full die separation while the dies are still attached to tape has been demonstrated.

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Section: D: Enhanced Die Fracture Strengthmentioning

confidence: 83%

Wafer Dicing Using Dry Etching on Standard Tapes and Frames

Lishan

Lazerand

Mackenzie

et al. 2014

International Symposium on Microelectronics

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show abstract

“…Regarding prerequisite (2), the time for completely dissolving the adhesive photoresist following the DRIE strongly depends on the distribution and area density of the throughwafer trenches. As an alternative to the adhesive photoresist, a transparent adhesive called Crystalbond (Crystalbond 509, SPI Supplies) also can be used to temporarily bond the two wafers [16]. While Crystalbond has favorable thermal conductivity suitable for DRIE, it is necessary to grind it to a powder beforehand and dissolve it in acetone to prepare the material for bonding; processing that is often not desirable in a clean facility.…”

Section: Resultsmentioning

confidence: 99%

“…The outer and inner etched trenches on the front side have the same width of 110 μ m. It can be seen that the outer trench features a tether patterned with a stepwise shrinking width of trench along the <110 > direction. Due to the aspect ratio dependent etching (ARDE) of the RIE, the tether pattern will generate a notched tether between the ring arrays and the silicon substrate after etching [16–18]. The ARDE effect means that etching depth is dependent on etching width, i.e.…”

Section: Singulation Processmentioning

confidence: 99%

“…For efficient singulation of devices with arbitrary geometries, it is possible to obtain accurate alignment features by leveraging existing lithography-defined features and using deep reactive ion etching (DRIE). DRIE, commonly used in microfabrication processes, is a promising candidate to meet the requirement of high throughput and accurate pattern definition for singulation [16, 19, 26, 27]. To avoid the singulated CMUT chips unintentionally detaching during processes a de-tethering technique which the tethers are formed simultaneously with DRIE is employed [17, 24, 25].…”

Section: Introductionmentioning

confidence: 99%

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Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers

Chang¹,

Moini²,

Nikoozadeh³

et al. 2014

J. Micromech. Microeng.

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Singulation of MEMS is a critical step in the transition from wafer-level to die-level devices. As is the case for capacitive micromachined ultrasound transducer (CMUT) ring arrays, an ideal singulation must protect the fragile membranes from the processing environment while maintaining a ring array geometry. The singulation process presented in this paper involves bonding a trench-patterned CMUT wafer onto a support wafer, deep reactive ion etching (DRIE) of the trenches, separating the CMUT wafer from the support wafer and de-tethering the CMUT device from the CMUT wafer. The CMUT arrays fabricated and singulated in this process were ring-shaped arrays, with inner and outer diameters of 5 mm and 10 mm, respectively. The fabricated CMUT ring arrays demonstrate the ability of this method to successfully and safely singulate the ring arrays and is applicable to any arbitrary 2D shaped MEMS device with uspended microstructures, taking advantage of the inherent planar attributes of DRIE.

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“…This is a common method to test the mechanical strength of separated dies, and has thus already been used in several studies [6,8,10,18,[29][30][31]. The test procedure was as follows: chips were placed on two supports with a distance of L = 2 mm, a loading edge was lowered from the top until the chip was broken, and the breaking force F b was measured.…”

Section: Methodsmentioning

confidence: 99%

Ultrafast-laser dicing of thin silicon wafers: strategies to improve front- and backside breaking strength

Domke

Egle²,

Stroj

et al. 2017

Appl. Phys. A

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increase the distance between separated dies and step cuts to minimize the effect of decreasing fluence during scribing were performed. Bending tests revealed that breaking strengths of about 1100 MPa could be achieved also on the backside using the step cut. A reason for the superior performance could be found by calculating the fluence absorbed by the sidewalls. The calculations suggested that an optimal fluence level to minimize thermal side effects and periodic surface structures was achieved due to the step cut. Remarkably, the best breaking strengths values achieved in this study were even higher than the values obtained on state of the art ns-laser and mechanical dicing machines. This is the first study to the knowledge of the authors, which demonstrates that ultrafast-laser dicing improves the mechanical stability of thin silicon chips.

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Die separation and rupture strength for deep reactive ion etched silicon wafers

Cited by 12 publications

References 18 publications

Wafer Dicing Using Dry Etching on Standard Tapes and Frames

Wafer Dicing Using Dry Etching on Standard Tapes and Frames

Singulation for imaging ring arrays of capacitive micromachined ultrasonic transducers

Ultrafast-laser dicing of thin silicon wafers: strategies to improve front- and backside breaking strength

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