Glass Polishing Mechanisms

In polishing glass for optical use, the lens crafter is primarily interested in smoothing the surface. There have been several proposed mechanisms by which the glass surface is made smooth during polishing as reviewed by Holland and Izumitani. These 

Glass Softening Point (°C) Vickers Micro- hardness (kg/mm Acid Resistance Wata Resistance (% Weight Loss) (% Weight Loss)  

Polish rate vs. Vickors microhardness of various glasses listed in Table 5.1. (From Ref. (3).) 

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Fig. 10. Schematics of reaction mechanism between HjO and an SiOj surface in glass polishing (after Hayashi ei al. Ref. [6]).

Cornish, D. C. (1961). The Mechanism of Glass Polishing. A History and Bibliography. British Scientific Instrument Research Association Research Report R. 267. 

With suitable chemical, mechanical and heat treatment, glass polishing compounds of high quality have been produced from bastnaesite concentrates since 1965. 

Slurry Abrasive The slurry abrasive provides the mechanical action of CMP. Size and concentration slurry have a different effect on mechanical abrasion. However, the abrasive can also have a chemical effect as in the case of glass polishing with ceria abrasive where the ceria forms a chemical bond with the glass surface or in the case of alumina, which seems to create surface defects on SiOj films polished in pH, in the range of 5 to 8. 

Izumitani demonstrated that water is important to the polish mechanism because it provides the chemical component of the polish. During polishing, water entry into the oxide surface has the effect of softening the glass surface (Figure 5.4). The importance of water to glass and oxide polishing has been demonstrated by... 

The effect of pressure and velocity on the removal rate of oxide and metal films in a chemical-mechanical polish process has been widely investigated. Yet, there is no consensus and several different theoretical models have been proposed. Most of them take the form R = KP V where R denotes the polish rate, K is a proportionality constant, P is the applied downward pressure, V is the velocity, and a and b are constants that take fractional values between 1/3-1. When a and b are both equal to 1, this equation becomes the Preston equation, well known in optical glass polishing industry. 

In ellipsometric studies of electrochemical systems the test specimens are usually electrodes immersed in electrolyte solutions. The electrode must be flat and well polished. Mechanical polishing is often finished with 0.05-jum polishing powder. Alternatively, vacuum-deposited metals on glass slides are used as electrodes. An electrochemical cell has to be designed so that light can pass through windows made of strain-free optically uniform glass or... 

Glass-reinforced aluminum foil with either a bright polished or white lacquer surface is utilized with most types of insulant. Primarily it is used as a vapor control layer or as a means of upgrading the fire properties of plastic foams, but it does give a semi-decorative finish to the insulation. It is therefore often use where the insulation is open to view but located away from direct risk of mechanical damage. 

The introduction of the sample into the adsorbent layer is a critical process in HPTLC. For most quantitative work a platinum-iridium capillary of fixed volume (100 or 200 nL), sealed into a glass support capillary of larger bore, provides a convenient spotting device. The capillary tip is polished to provide a smooth, planar surface of small area (ca 0.05 mm2), which when used with a mechanical applicator minimises damage to the surface of the plate spotting by manual procedures invariably damages the surface. 

Researchers in Japan have determined that copper interconnects deposited by metallo-organic chemical vapor deposition (MOCVD), then followed by chemical mechanical polishing, provides sub-quarter-micron interconnects and can be achieved on a production basis. Titanium nitride and borophosphosilicate glass provide effective barriers against copper diffusion.PL[H]... 

Borst, C. L., Gill, W. N., and Gutmann, R. J., Chemical-Mechanical Polishing of Low Dielectric Constant Polymers and Organosilicate Glasses, Boston Kluwer Academic Publishers, 2002, pp. 1-5. 

Figure 33 Comparison of heat transfer mechanisms for glass vials on a polished stainless steel shelf. Pressure is in millitorr. The vial identification numbers are manufacturers designations. (From Ref. 1.)...

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