Conditioning Abrasive Particle for Sapphire Fine Lapping with a Diamond Agglomerate Fixed Abrasive Pad
Publication Date: 2014-Jun-16
The IP.com Prior Art Database
A fixed abrasive lapping pad, having diamond agglomerate as the abrasive particle was used to lap C-plane sapphire wafers. A coolant was used that contained silicon carbide (SiC) particles or alumina particles as conditioning particles to condition or dress the fixed abrasive during the lapping process. Sapphire wafers lapped with coolants containing SiC conditioning particles have higher removal rates than wafers lapped with a coolant having alumina conditioning particles. At comparable SiC and alumina particle sizes, 3-4 micron, sapphire wafers lapped with coolants containing SiC conditioning particles resulted in a somewhat higher Ra than that exhibited by sapphire wafers lapped with coolants containing alumina conditioning particles.
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Conditioning Abrasive Particle for Sapphire Fine Lapping with a
Diamond Agglomerate Fixed Abrasive Pad
The polishing or lapping of hard substrates, such as sapphire wafers, is typically accomplished by slurry or fixed abrasive processes. There is usually a tradeoff between the removal rate and the surface roughness of the substrate, as the removal rate increases (desirable) the surface roughness increases (undesirable). The industry is continually looking for new processes/technology to overcome this issue. WO 2007/015909A describes a fixed abrasives system using agglomerates of a first abrasives suitable for abrading or polishing the substrate and conditioning particles suitable for conditioning or dressing the agglomerate of the fixed abrasive and/or the polymeric matrix of the fixed abrasive. It was found that the use of alumina conditioning/dressing particles can drastically improve the removal rate with minimum sacrifice of surface roughness.
Fixed Abrasive Pad
A fixed abrasive pad is prepared according to the procedure described in WO2007/015909, "Fixed Abrasive Article Preparation (Method I)". The abrasive particle is a 4 micron diamond abrasive particle.
Seven conditioning particles of varying particle sizes; platelet calcined alumina (PWA - 3 micron), white fused alumina (WA - 3 micron and 7 micron), green silicon carbide (SiC-GC - 1.2 micron, 2 micron and 4 micron), black silicon carbide (SiC-C - 3 micron); available from Fujimi Corporation are used.
Lapping Test Method
A 200 mm diameter fixed abrasive pad is attached to the 200 mm diameter bottom platen of a Buehler single side polisher using a pressure sensitive adhesive. Two 2-inch diameter C-plane sapphire wafers having a Ra of about 1,000 nm are attached using wax to the wafer platen (top platen) and lapping is conducted with the fixed abrasive pad in conjunction with a...