Characterization of an ultrathick positive photoresist for electroplating applications

Avrit, Brad; Maxwell, Edward W.; Huynh, Lisa M.; Capsuto, Elliott Sean

doi:10.1117/12.537120

Cited by 9 publications

(4 citation statements)

References 8 publications

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“…A thick photoresist layer is needed for a copper pillar process, since the entire solder volume is contained by the photoresist mold. Typical thicknesses for mushroom-free processes are in the 40 to 100 μm range [6,7]. While electroplating metals into features of this size is a well-established technology, fabricating the high aspect ratio features needed for these applications is placing new demands on photoresists and lithography equipment.…”

Section: Introductionmentioning

confidence: 99%

“…With thick films, the concerns are centered around aspect ratios, downstream plating performance, exposure and focus latitudes, and productivity. As spin-coated photoresist films become more popular for these applications, it is important to study thicker coatings to determine how they might be optimized for performance and productivity [7,8,9].…”

Section: Introductionmentioning

confidence: 99%

“…Traditionally, photoresists useful in the 50 μm to 100 μm range are very difficult to formulate, especially in a positive tone. Advantages of positive tone photoresists include stripability, outgassing control, and compatibility with a dark field reticle [7,8,9]. It is very difficult to design a positive tone photoresist with the necessary transparency, resulting in ultra-high exposure doses.…”

Section: Introductionmentioning

confidence: 99%

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Performance of a 55-micron copper pillar bump process using a positive thick chemically amplified photoresist

Crapse¹,

Flack²,

Nguyen³

et al. 2007

Proceedings of SPIE

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As pin counts and interconnection densities increase there is growing interest in copper pillar bumps for flip chip and wafer-level packaging. Copper pillars retain their shape in both the x, y and z directions during solder reflow, allowing finer interconnect pitches with predictable standoff heights. The fabrication of copper pillar bumps requires the use of a very thick photoresist layer for the copper electroplating. This photoresist material must be capable of coating, exposing, developing, electroplating and stripping with conventional equipment and standard ancillary process chemicals. In addition, photoresist sensitivity and process bake and development times are critical to minimize the cost of ownership of the lithography cell. For the electroplating process the photoresist profile, plating durability and stripability are important considerations. This study will characterize a novel photosensitive photoresist (Shin-Etsu SIPR 7123M) for a single coat, 55 μm thick copper process for a manufacturing environment. This photoresist has been formulated for enhanced photospeed, ease of stripability and has additives to eliminate the cracking often seen with very thick films. The lithographic performance of the thick positive photoresist will be optimized using a broad band, low numerical stepper. Enhanced process flexibility and productivity will be shown in regards to developer type and no wait times between process steps. Results will show excellent adhesion to copper with no surface treatment and no photoresist popping during exposure. Cross sectional SEM analysis, process latitude, and copper plating performance are used to establish the lithographic capabilities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Performance of a 55-micron copper pillar bump process using a positive thick chemically amplified photoresist

Crapse¹,

Flack²,

Nguyen³

et al. 2007

Proceedings of SPIE

View full text Add to dashboard Cite

show abstract

“…Today there is a rapid increase in the pin counts of most solder bump applications. The necessary corresponding reduction in bump pitch makes conventional "mushroom" type over plating impractical in high bump count devices [2,3,4,5]. Elimination of the umbrella requires even thicker photoresist layers since the entire solder volume is contained by the photoresist mold.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a high-photospeed positive thick photoresist for lead-free solder electroplating

Flack¹,

Nguyen²,

Washio³

et al. 2007

Proceedings of SPIE

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The introduction of lead free solder (SnAg) electroplating for advanced packaging applications has created new challenges for thick photoresist processes. Dry film laminate photoresist materials do not provide sufficient resolution or process control for the smaller bump diameters used with advanced design rules. The traditional positive tone DNQ-Novolak photoresists require large exposure doses and long processing times that are unacceptable for the total cost of ownership (COO) of the lithography cell in a manufacturing environment. Standard chemically amplified positive photoresists have interactions between the PAG and Cu or Cu 2 O at the soft bake step which makes it impossible to obtain sufficient pattern fidelity for electroplating lead free solder on copper seed layer substrates. This study will characterize a novel positive tone, chemically amplified photoresist (TOK PC-0059B PM) that can be double coated up to 100 μm thick for lead free solder electroplating. The PAG in the photoresist has been formulated to prevent any interaction with Cu or Cu 2 O. This photoresist exhibits extremely high photospeed, excellent pattern resolution and ease of stripability after electroplating. The lithographic performance of the thick positive photoresist will be optimized on 300mm wafers using a broad band, low numerical stepper. Enhanced process latitude and very high photospeeds will be demonstrated for thicknesses up to 100 μm. Cross sectional SEM analysis, process linearity, and electroplating performance are used to establish the lithographic capabilities.

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Photoresist Performance: An Exploration of Synthesis, Surface Modification Techniques, Properties Tailoring, and Challenges Navigation in Copper/Copper Oxide Nanoparticle Applications

Onivefu,

Efunnuga,

Efunnuga

et al. 2024

Biomedical Materials & Devices

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Characterization of an ultrathick positive photoresist for electroplating applications

Cited by 9 publications

References 8 publications

Performance of a 55-micron copper pillar bump process using a positive thick chemically amplified photoresist

Performance of a 55-micron copper pillar bump process using a positive thick chemically amplified photoresist

Characterization of a high-photospeed positive thick photoresist for lead-free solder electroplating

Photoresist Performance: An Exploration of Synthesis, Surface Modification Techniques, Properties Tailoring, and Challenges Navigation in Copper/Copper Oxide Nanoparticle Applications

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