Wafer Dicing is a backend process in semiconductor manufacturing. We often see wafer dicing equipment connected to a cutting fluid filling auxiliary machine (usually referred to as a dosing machine). In fact, the cutting fluid (Dicing Coolant / Dicing Fluid) plays a crucial role in this process.
1. Why Is Dicing Fluid Needed?
During wafer dicing, the diamond blade rotates at high speed (typically 30,000–60,000 rpm), causing intense friction and impact with the wafer material. Without control, this would lead to a series of issues. The core function of dicing fluid (dicing coolant) is to address these problems, with its main roles including:
1. Cooling：
This is the primary function. Friction generates massive heat, causing a sharp rise in local temperature. Excessively high temperatures can:
Damage chips: Induce thermal stress inside the wafer, leading to micro-cracks or even chipping – reducing the mechanical strength and electrical performance of chips, and creating hidden risks for subsequent wafer grinding or polishing.
Damage the blade: High temperatures oxidize or graphitize the diamond particles on the blade and soften the binder, accelerating blade wear and shortening its lifespan.
2. Lubrication：
Dicing fluid forms a lubricating film between the blade and the wafer, reducing frictional resistance. This:
Lowers cutting force: Makes the cutting process smoother, reduces mechanical stress, and thus minimizes chipping and cracking – ensuring the edge quality required for post-dicing precision grinding.
Improves cutting quality: Creates a smoother, cleaner dicing street (scribe line), avoiding irregular edges that could interfere with subsequent wafer handling or packaging.
3. Cleaning:
A large amount of contaminants such as silicon debris and slag are generated during cutting. Dicing fluid flushes these contaminants away from the dicing street and wafer surface using flowing liquid, preventing them from:
Re-adhering: Contaminating the wafer surface or chip functional areas – which would cause scratches during wafer polishing or affect bonding reliability.
Clogging the blade: Debris blocking the diamond particles on the blade reduces cutting efficiency and may even cause blade vibration, leading to more severe damage (e.g., edge chipping).
4. Anti-static Protection:
Friction generates static charges, which attract dust and particles. Many dicing fluids contain anti-static agents that neutralize static charges, keeping the wafer clean – critical for avoiding particle-induced defects in advanced processes like nanoscale polishing.
2. Which Types of Wafers Require Dicing Fluid?
Almost all mechanical blade dicing processes require dicing fluid. Specifically, the following scenarios are particularly critical:
1 Traditional Silicon (Si)-Based Wafers:
This is the most common application. Whether for logic chips, memory chips, or analog chips, as long as a diamond blade is used for cutting, dicing fluid must be used to control heat and stress – preventing defects that would complicate subsequent wafer back grinding or thinning.
2. Fragile and Brittle Material Wafers:
Compound semiconductors: Such as gallium arsenide (GaAs), indium phosphide (InP), silicon carbide (SiC), and gallium nitride (GaN). These materials are more brittle than silicon and highly sensitive to mechanical stress, so they have higher requirements for the lubrication and cooling performance of dicing fluid to prevent severe chipping (which would be irreparable during post-dicing abrasive finishing).
Glass, ceramic, and sapphire substrates: Used in MEMS sensors, RF devices, LEDs, etc. These materials are prone to cracks and chipping, and rely heavily on dicing fluid to ensure cutting quality – a prerequisite for achieving high flatness in subsequent sapphire polishing or ceramic grinding.
3. Wafers with Complex Structures:
3D stacked and packaged wafers: Such as through-silicon via (TSV) technology and 2.5D/3D packaging. These wafers have complex structures, and interlayer bonding forces may be weak points. They require a gentle yet efficient cutting process supported by high-performance dicing fluid – preventing damage to internal connections that would affect final device performance.This is the primary function. Friction generates massive heat, causing a sharp rise in local temperature. Excessively high temperatures can:
Thinned wafers: Wafers are ground to a thickness of 100 μm or even 50 μm before dicing, making them very soft and fragile. Dicing fluid must provide excellent cooling and lubrication to prevent warpage and breakage (which would render them unusable for subsequent CMP planarization).
Low-k dielectric material wafers: Low-k materials have low mechanical strength, are porous and fragile, and are prone to delamination during cutting. Dicing fluid helps reduce stress to avoid this issue – ensuring the integrity of the dielectric layer for post-dicing metal deposition.