Evaluation Of Uniaxial Bending Strength On The Inactive Backside Of Dram Chips

Johnson, Elnathan (2026) Evaluation Of Uniaxial Bending Strength On The Inactive Backside Of Dram Chips. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pesatnya perkembangan *High-Bandwidth Memory* (HBM) dan teknologi pengemasan tiga dimensi meningkatkan kebutuhan akan chip DRAM *ultra-thin* dengan keandalan mekanis yang tinggi. Penipisan wafer secara agresif membuat die DRAM rentan terhadap tegangan bending, cacat permukaan, dan patah dini. Penelitian ini menguji kekuatan bending unaksial chip DRAM DDR3 berketebalan 115 µm dengan membandingkan metode *Three-Point Bending* (3PB) konvensional dan *Load-on-Elastic-Foundation* (LoEF) pada sisi aktif (*integrated circuit*/IC) dan sisi *ground* (belakang) untuk mengevaluasi kekuatan permukaan, perilaku patahan, dan distribusi keandalan. Hasil eksperimen menunjukkan bahwa sisi IC memiliki kekuatan bending yang stabil, yaitu 335–337 MPa pada kedua metode pengujian. Sebaliknya, sisi *ground* sangat sensitif terhadap metode pengujian, dengan kekuatan terukur mencapai 424,7 MPa pada uji LoEF, tetapi menurun menjadi 254,4 MPa pada uji 3PB akibat kegagalan dini yang dipicu oleh cacat tepi dan retak mikro (*micro-cracks*) hasil proses *back-grinding*. Temuan ini membuktikan bahwa uji 3PB dapat mengestimasi lebih rendah (*underestimate*) kekuatan permukaan sebenarnya ketika kegagalan didominasi oleh cacat tepi. Analisis Weibull mengonfirmasi bahwa distribusi cacat pada sisi IC lebih seragam, sedangkan sisi *ground* memiliki dispersi data yang lebih tinggi dan keandalan yang lebih rendah. *Effective Young’s modulus* yang terukur sekitar 55 GPa, jauh lebih rendah dibandingkan silikon murni, mengindikasikan perilaku struktur komposit. Secara keseluruhan, pengujian LoEF terbukti lebih akurat untuk mengevaluasi kekuatan permukaan sebenarnya pada chip DRAM *ultra-thin* karena mampu meminimalkan kegagalan yang dipicu oleh cacat pada area tepi.
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The rapid development of *High-Bandwidth Memory* (HBM) and advanced three-dimensional packaging technologies has increased the demand for ultra-thin DRAM chips with high mechanical reliability. Aggressive wafer thinning makes DRAM dies more susceptible to bending stress, surface defects, and premature fracture. This study investigates the uniaxial bending strength of 115 µm-thick DDR3 DRAM chips by comparing two mechanical testing methods: the conventional *Three-Point Bending* (3PB) test and the *Load-on-Elastic-Foundation* (LoEF) test. Both the active integrated circuit (IC) side and the ground backside of the DRAM chips were evaluated to assess surface strength, fracture behavior, and reliability distribution. The experimental results show that the IC side exhibits stable bending strength ranging from 335 to 337 MPa under both testing methods. In contrast, the ground side is highly sensitive to the testing method, achieving a measured strength of 424.7 MPa under the LoEF test but decreasing to 254.4 MPa under the 3PB test due to premature failure triggered by edge defects and back-grinding-induced micro-cracks. These findings demonstrate that the conventional 3PB test can underestimate the actual surface strength when fracture is dominated by edge-related defects. Weibull analysis further confirms that the IC side has a more uniform defect distribution, whereas the ground side exhibits greater data dispersion and lower reliability. The measured effective Young’s modulus is approximately 55 GPa, which is substantially lower than that of bulk silicon, indicating the composite nature of the DRAM chip structure. Overall, the LoEF test provides a more accurate approach for evaluating the intrinsic surface strength of ultra-thin DRAM chips by minimizing edge-induced premature failures.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Ultra-thin DRAM chip, Uniaxial bending strength, Three-point bending test, Load-on-Elastic-Foundation test, Weibull analysis, Back-grinding defects, High-bandwidth memory.
Subjects:	T Technology > TJ Mechanical engineering and machinery
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Elnathan Johnson
Date Deposited:	03 Aug 2026 03:21
Last Modified:	03 Aug 2026 03:21
URI:	http://repository.its.ac.id/id/eprint/142015

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