Porous vacuum chucks – types of chucks

Types of porous vacuum chucks

Several types of porous vacuum chucks are available today on the market: cylindrical porous chucks, push-up table porous chucks, heater table porous chucks, built-in heater porous chucks among others. Different applications require different types of porous chucks.

Porous vacuum chuck structure

STRUCTURE

Chuck adsorption surface with flatness below 5µm allows a perfectly stable work platform. Depending on the body shape and other conditions, it is possible to create a porous surface with flatness under 3µm. The chuck is made up by a metal body matched with a porous substance

POROUS MATERIAL

(usually, ceramics) which constitutes the base supporting the substrate. By applying a negative pressure behind the porous layer, it is possible to create a very stable platform that holds the substrate firmly. A vacuum pump placed behind the porous literally sucks the air through the pores creating a very uniform negative pressure.
Chuck adsorption surface with flatness below 5µm allows a perfectly stable work platform. Depending on the body shape and other conditions, it is possible to create a porous surface with flatness under 3µm

Conditions applicable to porous vacuum chucks

Porous vacuum chucks differ by shape, size, type of porous material, material of the body, surface treatment of the body, Diameter of the porous holes and other factors

Proposals according to customer expectations and required applications

Shape
- rounded
- squared
- cylindrical
- special shape
Material of body
- stainless
- titan alloy
- aluminium
- ceramics
Size
- rounded shape (φ5mm~φ500mm)
- squared shape (φ5mm~φ350mm)
Body surface treatment
- fluorine resin processing
- anodized aluminium
- anti-rust coating process
- electroless nickel plating
Porous material
- ceramic
- conductive ceramics
- special material
Porous hole diameter
- 3µm~580µm

Porous vacuum chuck fabrication workflow

In order to successfully fabricate a good porous chuck, it is necessary to choose the right combination of body material, shape, working temperature and porous material (specification, features). For the porous layer usually alumina ceramic is used, for special applications carbon, super-hard, conductive ceramic material can be used. For the body: SUS, aluminium, ceramic material, titanium and other materials can be used. The porous layer is polished down to a flatness of few µm, with the step between the body and the porous surface reduced to zero.

Porous vacuum chuck fabrication workflow

Typical applications for porous vacuum chucks

Porous chucks are indispensable parts of semiconductor world. Polishing, dicing, bonding and others are among the processes that require very thin wafers to be secured firmly to a piece of equipment. Recently, new applications in the thin-film solar panel, nanoimprint are entering the spotlight. Other applications include laser fabrication of metal and resin and printing.

Carbon porous chuck

New conductive carbon material with properties similar to glass!

Benefits

Removal of electrical charge
(the chuck can conduct current but does not get charged easily).
Can handle materials that get damaged or scratched easily
(this is one of the peculiarities of our glass-like carbon material)
Possible to be used for measurement or visual analysis with materials
which are subject to halation
Can be used in applications involving probe testers, etc.

Features

No dust emissions as the chuck material is completely glass-like carbon
Electric conductivity (specific resistance: 2.4×10-2)
Resistant to heat and to corrosion, especially corrosion from gases and liquids)
No color stain like in case of graphite

Applications

Semiconductor manufacturing equipment
Semiconductor inspection equipment, measurement equipment, visual inspection equipment, wafer patterning equipment (E-beam), optical microscopy
FPD manufacturing equipment
Porous surface features specifications

Surface comprises carbon particle sizes with diameter of 100µm,200µm and 400µm.

PropertyValue

Bulk density [Mg/m3]0.98

Porosity [%]45.9

Bending modulus [GPa]8.8

Bending strength [MPa]30

Resistivity [Ω · cm]2.4×10-2

Shore hardness [HS]42

Ash content [ppm]77

Thermal conductivity [W/m.K]1.00
Hot vacuum chuck

Allows to heat or cool the substrate while under vacuum suction!
Benefits
- The surface can be heated up to 250 ℃
- Possible to heat or cool the same substrate
- Heating possible while under vacuum suction
Features
- Endures several cycles of heating and cooling
- Simple design that allows the substrate to be attached easily and seamlessly
- Can be used in combination with 6, 8 and 12-inch round substrates and □ 150, □ 200, □ 250 squared substrates
Applications
- Electrical conductivity test while heated
- Semiconductor manufacturing process test under vacuum
- Wafer-level bonding
- Wafer getting bonded through thermo-setting
Heating and cooling experimental results

With temperature-fixed heating or cooling cycles, it is possible to have full substrate vacuum adsorption.

It is possible to see that the temperature rises within the wafer and on the edge of the wafer in an uniform way and according to the cycle set by the operator

Similarly as during the heating cycle, during the cooling cycle it is possible to see that the temperature decreases uniformly within the wafer and at the edge.
Self-absorption chuck

All-in-one porous chuck with pump and battery embedded in the structure. Reaching low cost through integrated functionality! When using alkaline AA battery four, time is about 7 hours. Working time may vary depending on conditions.
Benefits
- Can be used without external pump or battery
- This innovative design saves space
- Easy to carry
Features
- Compact and wireless design
- LED display functionality included
- Can be adapted to substrates of different sizes and shapes
Applications
- Semiconductor manufacturing equipment
  Semiconductor inspection equipment, measurement equipment, visual inspection equipment, wafer patterning equipment (E-beam), optical microscopy, FPD manufacturing equipment
- Possible to work in laboratories with no vacuum facilities
- Wafer vacuum suction
Example of carry-by-hand
Surface light-emitting porous chuck

The contour of the work area emerges clear!
Benefits
- Substrate-holding chuck with backlight features
- Possible to have the working area changed according to application
- Illumination uniformly distributed all over the surface. No light and dark variations.
- Amount of light can be set up to 10,000 lx
Feature
- Power and vacuum pump, so all-in-one Compact and wireless
- Reject the work is easily blown up mode
- LED lamp display function
- Compatible with various size, shape, and color variations
Applications
- Image analyzer, drawing equipment, measurement equipment, Installation and inspection of the equipment, the existing table Displacement from
- Such as in laboratory without vacuum generation equipment Vacuum suction of work
- Vacuum suction of the wafer
Inspection method comparison

Traditional inspection method vs. inspection method by PC

Ceramic Chuck Table

Thursday, October 23, 2014