Deep Etching of Single- and Polycrystalline Silicon with High Speed, High Aspect Ratio, High Uniformity, and 3D Complexity by Electric Bias-Attenuated Metal-Assisted Chemical Etching (EMaCE)

Li, Liyi; Zhao, Xueying; Wong, Ching‐Ping

doi:10.1021/am504046b

Cited by 52 publications

(38 citation statements)

References 30 publications

(53 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar results were also reported by other research groups [20], [21]. Furthermore, we demonstrated the effect of electric bias in controlling the sidewall tapering angle of the etching profile in MaCE [22]. These findings pave the way for the application of MaCE in TSV fabrication.…”

supporting

confidence: 91%

“…The sidewall and top surface of Si that is covered by the photoresist appear smooth and clean, indicating that no excessive etching occurred in this region. In contrast, if a p-type Si was used, the sidewall and top surface of Si would become porous under the same etching [22]. The result confirms that in MaCE of n-type Si, the etching on the sidewall of TSV is intrinsically suppressed.…”

Section: Resultssupporting

confidence: 59%

“…Because this paper only focuses on the method of hole formation, the word TSV in the following text only refer to the vertical holes on Si for the convenience of discussion. Previously, as an attempt, MaCE for TSV fabrication has been conducted on p-type Si [22]. After MaCE, the sidewall of TSVs were found severely roughened and tapered, unless a cathodic electric bias was applied on the Si during MaCE.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Formation of Through Silicon Vias for Silicon Interposer in Wafer Level by Metal-Assisted Chemical Etching

Zhang

Wong

2015

IEEE Trans. Compon., Packag. Manufact. Technol.

Self Cite

View full text Add to dashboard Cite

This paper reports a novel wet chemical etching method, referred to as uniform metal-assisted chemical etching (MaCE), for uniform hole formation in fabrication of through silicon vias (TSVs) on silicon (Si) interposer in wafer level. In MaCE, a layer of Au as catalyst is deposited on the photolithography-patterned Si surface. Uniform holes are formed by simply immersing the Au-loaded Si into a hydrofluoric acid-hydrogen peroxide aqueous solution. In a typical experiment, ∼1 million holes are formed after MaCE for 4 h at room temperature over a 4-in Si wafer with a diameter of 28 µm, a depth of 162 µm, a pitch size of 80 µm, and a sidewall roughness below 50 nm. The holes show high geometric uniformity in wafer level, with their depth in the range 159-164 µm, the diameter in 27.1-29.7 µm, and high verticality. Simultaneous etching of two wafers in the same batch is also demonstrated. The TSV etched by MaCE show compatibility with SiO 2 deposition by plasma-enhanced chemical vapor deposition and copper filling by electroplating. The reported method provides an approach for manufacturing TSV on Si interposer with simple operation, high geometric uniformity, high throughput, and low cost. Index Terms-Metal-assisted chemical etching (MaCE), silicon interposer, through silicon vias (TSVs).

show abstract

supporting

confidence: 91%

Section: Resultssupporting

confidence: 59%

mentioning

confidence: 99%

See 1 more Smart Citation

Formation of Through Silicon Vias for Silicon Interposer in Wafer Level by Metal-Assisted Chemical Etching

Zhang

Wong

2015

IEEE Trans. Compon., Packag. Manufact. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…When a negative bias is applied, this should significantly increase the hole injection rate, and thus the etch rate, at the metal/Si interface. However, under a negative applied bias, reported works have shown either just a small increase53, or on the contrary, reducing etch rates50. While the effects on ion movements through such applied bias is yet unclear, our work shows clearly why there is no substantial increase in etching since the charge transfer is a redox driven reaction.…”

Section: Resultsmentioning

confidence: 53%

Evidences for redox reaction driven charge transfer and mass transport in metal-assisted chemical etching of silicon

Kong

Dasgupta

Ren

et al. 2016

Sci Rep

View full text Add to dashboard Cite

In this work, we investigate the transport processes governing the metal-assisted chemical etching (MacEtch) of silicon (Si). We show that in the oxidation of Si during the MacEtch process, the transport of the hole charges can be accomplished by the diffusion of metal ions. The oxidation of Si is subsequently governed by a redox reaction between the ions and Si. This represents a fundamentally different proposition in MacEtch whereby such transport is understood to occur through hole carrier conduction followed by hole injection into (or electron extraction from) Si. Consistent with the ion transport model introduced, we showed the possibility in the dynamic redistribution of the metal atoms that resulted in the formation of pores/cracks for catalyst thin films that are ≲30 nm thick. As such, the transport of the reagents and by-products are accomplished via these pores/cracks for the thin catalyst films. For thicker films, we show a saturation in the etch rate demonstrating a transport process that is dominated by diffusion via metal/Si boundaries. The new understanding in transport processes described in this work reconcile competing models in reagents/by-products transport, and also solution ions and thin film etching, which can form the foundation of future studies in the MacEtch process.

show abstract

“…In the low-ρ etchant solution, the sidewall of the 3D profile can be either vertical or tapered. 20,21 In the context of MaCE for microstructures fabrication (referred to as micro-MaCE), controllability of the 3D profile has not been well studied.…”

mentioning

confidence: 99%

Charge Transport in Uniform Metal-Assisted Chemical Etching for 3D High-Aspect-Ratio Micro- and Nanofabrication on Silicon

Zhao

Wong

2015

ECS J. Solid State Sci. Technol.

Self Cite

View full text Add to dashboard Cite

Recently, metal-assisted chemical etching (MaCE) has been proposed as a promising method for micro-and nanostructures fabrication on silicon (Si) with high aspect ratio, high geometric uniformity and low cost. In MaCE, electron holes (h + ) are injected into Si through catalytic reduction of H 2 O 2 on metal catalyst thin film patterns. Si beneath the metal is etched through a redox reaction where h + are involved. This work investigated a fundamental electrochemical process during MaCE: the transport of h + , and revealed its unique correlation with the 3D profile of the etching results. It is discovered that under the uniform etching condition, etching occurs both in the Si beneath the catalysts as well as on the sidewall of the etched space. On N-type Si, the sidewall etching is intrinsically depressed, and highly vertical HAR structures are formed; on P-type Si and undoped Si, the sidewall tapering becomes significant as the pattern number and density increase. The variation of the 3D profile can be explained by the CT during etching using a Schottky junction model, which show dependence on the intrinsic properties of the Si. CT involved in the two etching process can further be correlated by diffusion or drift of h + , which explains the influence of catalysts geometry. Fabrication of micro-and nanostructures on silicon (Si) is a key step in manufacturing of modern electronic and optoelectronic devices. Especially, the high-aspect-ratio (HAR) structures, of which the vertical dimension is much larger than the lateral dimension, enable orders-of-magnitude higher integration density and superior system performance compared to that of traditional planar structures by utilizing the space inside Si. HAR structures, such as deep trenches and deep holes, have been widely used in advanced Si-based devices. For example, deep trenches are the core structures in the microelectromechanical systems; 1 deep holes serve as the interconnect routes in the emerging 3D integration technology in microelectronic packaging. 2Most of these HAR structures are fabricated by selective removal of certain volume of Si from the bulk Si substrate, which is generally referred to as the etching of Si. Until now, the major applicable Si etching method for HAR structures fabrication is the deep reactive ion etching (DRIE). 3,4 In DRIE, Si is put in a gas chamber and etched by plasma. Although DRIE is able to fabricate a wide range of HAR structures, it is suffered from high cost. On the other hand, metal-assisted chemical etching (MaCE), a novel low-cost wet chemical etching method, has attracted attention from both academia and industry.

show abstract

Deep Etching of Single- and Polycrystalline Silicon with High Speed, High Aspect Ratio, High Uniformity, and 3D Complexity by Electric Bias-Attenuated Metal-Assisted Chemical Etching (EMaCE)

Cited by 52 publications

References 30 publications

Formation of Through Silicon Vias for Silicon Interposer in Wafer Level by Metal-Assisted Chemical Etching

Formation of Through Silicon Vias for Silicon Interposer in Wafer Level by Metal-Assisted Chemical Etching

Evidences for redox reaction driven charge transfer and mass transport in metal-assisted chemical etching of silicon

Charge Transport in Uniform Metal-Assisted Chemical Etching for 3D High-Aspect-Ratio Micro- and Nanofabrication on Silicon

Contact Info

Product

Resources

About