&lt;title&gt;Transport limitations in electrodeposition for LIGA microdevice fabrication&lt;/title&gt;

Griffiths, Stewart K.; Nilson, Robert H.; Bradshaw, Robert W.; Ting, A.; Bonivert, William D.; Hachman, John T.; Hruby, Jill M.

doi:10.1117/12.324324

Cited by 17 publications

(14 citation statements)

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“…al. 64 In the former case, the insulating PMMA mask was shown to have strongly diminished mixing, resulting in lower transport rates of the reacting ions, while in the latter case, buoyancy-driven transport rates into deep high aspect ratio features higher than those expected from pure diffusion control were observed. Since Leyendecker et.…”

Section: Table 1 Experimental Data From Griffiths Et a L ~~mentioning

confidence: 98%

“…64 Nilson and Griffiths present more detailed calculations of natural convection in high aspect ratio trenches in a subsequent article.6s They find that the relative importance of natural convection depends on the feature geometry and the inclination of the substrate. The authors conclude that some mixing from natural convection is expected to occur in features having aspect ratios less than 1.2, 6.6, and 37 for resist thicknesses of 0.1, 1.0, and 10 mm, respectively.…”

Section: Table 1 Experimental Data From Griffiths Et a L ~~mentioning

confidence: 99%

“…The data for the experimental conditions they reported are reproduced in Table 1. 64 Measured current efficiencies indicate that hydrogen evolution…”

Section: -57mentioning

confidence: 99%

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LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

Kelly

Goods

2005

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The report presented below is to appear in EEectrochernistry at the Nanoscale, Patrik Schmuki, Ed. Springer-Verlag, (ca. 2005). The history of the LIGA process, used for fabricating dimensional precise structures for microsystem applications, is briefly reviewed, as are the basic elements of the technology. The principal focus however, is on the unique aspects of the electrochemistry of LIGA through-mask metal deposition and the generation of the fine and uniform microstructures necessary to ensure proper functionality of LIGA components. We draw from both previously published work by external researchers in the field as well as from published and unpublished studies from within Sandia.

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Section: Table 1 Experimental Data From Griffiths Et a L ~~mentioning

confidence: 98%

Section: Table 1 Experimental Data From Griffiths Et a L ~~mentioning

confidence: 99%

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LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

Kelly

Goods

2005

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“…In order to maintain the precision of pattern transfer from the resist to the final product, effective electroforming processes are necessary. However, challenges remain for the electroplating of HARMS (Griffiths et al 1998;Chen et al 2004). The electrodeposition of HARMS is normally under diffusion control, because the electrolyte in deep structures remains nearly stagnant in spite of vigorous agitation.…”

Section: Introductionmentioning

confidence: 98%

Fabricating HARMS by using megasonic assisted electroforming

et al. 2008

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Electroforming is a main fabrication method to produce metal microstructures for microelectromechanical systems. Since the mass transport is limited in high aspect ratio microstructures (HARMS), problems such as uneven filling and void formation are often involved in the electroplating of deep molds. In this work, megasonic agitation is employed to improve the electroplating of HARMS, which causes little damage to the resist structure and is thereby advantageous over ultrasonic agitation. Cantilever beams and gaps with a linewidth of 10 lm and an aspect ratio of 25 have been obtained. The main effects of megasonic agitation are analyzed. The results indicate that resonant bubbles in the electrolyte are probably responsible for the mass transport enhancement during the electroforming process.

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“…Minimum feature size is likewise affected by a number of factors. Developing and electroplating small features having aspect ratios much above 20 are extremely difficult since diffusion-limited transport rates yield dissolution and metal deposition rates that are very small [7,8]. As a result, the ratio of the minimum feature size to the part thickness is now limited to about one part in 20, well below that of conventional manufacturing methods.…”

Section: Introductionmentioning

confidence: 99%

The influence of feature sidewall tolerance on minimum absorber thickness for LIGA x-ray masks

Griffiths¹,

Hruby²,

Ting³

1999

J. Micromech. Microeng.

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Minhnizing mask absorber thickness is an important practical concern in producing very small features by the LIGA process. To assist in this minhhization, we have developed coupled numerical models describing both the exposure and development of a thick PMMA resist. The exposure model addresses multi-wavelengt& one-dimensional x-ray transmission through multiple beam filters, through the mask substrate and absorber, and the subsequent attenuation and photon absorption in the PMMA resist. The development model describes one-dimensional dissolution of a feature and its sidewalls, taking into account the variation in absorbed dose through the PMMA thickness. These exposure and development models are coupled in a single interactive code, permitting the automated adjustment of mask absorber thickness to yield a prescribed sidewall taper or dissolution distance. We have used this tool to compute the minimum required absorber thickness yielding a prescribed sidewall tolerance for exposures performed at the ALS, SSRL and NSLS synchrotrons sources. Results are presented as a fhnction of the absorbe"d dose for a range of the prescribed sidewall tolerance, feature size, PMMA thiclmess, mask substrate "thickness and the development temperature.

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<title>Transport limitations in electrodeposition for LIGA microdevice fabrication</title>

Cited by 17 publications

References 0 publications

LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

Fabricating HARMS by using megasonic assisted electroforming

The influence of feature sidewall tolerance on minimum absorber thickness for LIGA x-ray masks

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