Silicon Chips

The extraordinary improvement of microfabrication and etching technology and abundant engineering data enable Creative Biolabs to provide stable high-resolution silicon microfluidic chip manufacturing services for clients from all over the world. Our processing capabilities cover wafers from 1 to 12 inches, and achieve stable manufacturing accuracy at the micron level.

Silicon Chips

Many technologies in microfluidic chip manufacturing are directly transformed from the microelectronics or semiconductor machining industry. Compared with metal materials, silicon has excellent manufacturability, chemical inertness and biocompatibility. Silicon has become a favorable material for chemical and biological applications in microfluidic systems. Silicon wafers for microfluidic applications are manufactured by controlled and slow pulling of cylindrical silicon crystals in baths of ultra-pure silicon and cutting into slices hundreds of microns thick. An optimized polishing method can give silicon crystals a quasi-atomically smooth surface. Silicon materials have been widely used in microfluidic chips with high complexity and high-resolution requirements, including micro reaction chambers, cell culture units, electrospray devices, digital microfluidics, etc.

Advantages of Silicon-based Chips

• Years of development and mature and stable photolithography protocols give silicon the best processability and predictability, which means the highest precision, the smallest error, and the best surface flatness. In fact, the fabrication accuracy of silicon chips can achieve an astonishing sub-micron level.
• The properties of silicon have been extensively verified and documented.
• Silicon has high mechanical strength and anisotropy, it can be used for complex precise 3D structures construction.
• Surface silanols can be modified by reaction with silylating reagents, and highly planar surface allows for further patterning and modification.
• A well-sealed silicon chip exhibits almost no leakage and is less permeable to gases.
• Silicon has excellent thermal properties, in fact, silicon-based chips have the best thermal conductivity among common microfluidic chip materials, and hardly produce any thermal expansion, which is very practical in experiments related to heat generation or temperature manipulation.
• Undoped silicon is an insulator at room temperature, but it can be easily integrated with electronic circuits.
• Silicon is chemically inertness and heat resistant which makes it can withstand processing procedures that are destructive to other materials.

Fig 1. Silicon chip covered by a glass plate. (Yadavali, et al., 2019)

It should be noted that silicon has many disadvantages due to the inherent properties of the material itself, which must be taken into account during chip development.

• Silicon is a fragile material that requires extra care in experimental manipulations.
• Silicon is opaque and optical detection is completely incompatible with silicon chips if not mixed with other materials.
• The manufacturing process of silicon requires complex and precise instruments and a high-clean processing environment, and its bonding and drilling processes are also more complicated and expensive.

Table.1 Property of silicon.

Services

Silicon-based microfluidic chips are widely used in digital PCR, droplet generation, DNA synthesis or the development of digital microfluidic systems. Such chips are mainly manufactured by photolithography and etching. Cutting-edge photolithography technology and improved etching craft allow Creative Biolabs to control the geometry of silicon chips within a few microns. Abundant engineering experience and data accumulation allow us to provide you with 2-5 inches (commonly used, other sizes are also optional) silicon wafer fabrication service, and achieve an accuracy of a few microns with a controllable channel height of 5-400 μm (error ~10%). The advanced photolithography concept also allows us to process photolithography molds with different heights. The most commonly used wafer thickness for silicon-based chips is 500μm, but we are more than happy to provide with other optional thicknesses according to your specific needs.

High-precision silicon-based models for rapid reprinting of PDMS chips in a laboratory environment are also available. Please don't hesitate to contact us for any needs.

Reference

1. Yadavali, S.; et al. Robust Microfabrication of Highly Parallelized Three-Dimensional Microfluidics on Silicon. bioRxiv. 2019, 5, 625277.