JPH0132174B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface treatment of glass, and in particular to a method for surface treatment of glass that has a high surface smoothness and is less likely to be damaged by high-energy light irradiation. For example, glass substrates for liquid crystal televisions and glass substrates for field effect transistors are subjected to laser annealing to lower the resistance of polysilicon formed on the substrate and to increase the grain size of the semiconductor crystals. In this case, the glass substrate may be damaged due to lattice vibrations caused by the high energy of the laser beam, stress caused by light irradiation concentrated on minute defects in the glass, or temperature differences caused by partial laser irradiation. Ion exchange methods have been considered as a means of strengthening glass. However, simply applying compressive stress to the glass surface using the ion exchange method increases the mechanical strength, but has the disadvantage that the yield is poor. In other words, when ion exchange is performed on glass obtained by polishing raw glass into a predetermined shape and size, thermal stress occurs in the polishing scratches, causing cracks and resulting in defective products, resulting in a decrease in yield. This has the inconvenience of causing The occurrence of this minute crack is
This is particularly important for mask glass for LSIs, glass for LCD televisions, and general optical glass, which require high smoothness. The reason for this is that if there is light scattering due to defects, images cannot be accurately captured. The inventors of the present invention focused on these points, and as a result of further investigation, it was determined that the occurrence of the cracks was caused by the erosion of the molten salt for ion exchange, starting from the scratches remaining on the glass surface. The problem can be solved by reducing the size of the scratches remaining on the glass surface to 10μ or less, and then heat-treating at a constant temperature increase rate before ion-exchange treatment, and then irradiating with light after ion-exchange to diffuse and stabilize the ions. I found out that it can be done. The light source used may be laser light, visible light, or ultraviolet light. The present invention is based on the above knowledge and aims to easily obtain glass with high surface smoothness without particularly requiring complicated operations. That is, the present invention comprises a step of polishing the processed glass to reduce the size of residual scratches to 10μ or less, a step of heating the polished glass to a temperature lower than its softening point at a rate of 100° C./sec or less, and a step of heating the polished glass to a temperature lower than its softening point at a rate of 100° C./sec or less. This is a glass surface treatment method comprising the steps of ion-exchanging the ion-exchanged surface, and irradiating the ion-exchanged surface with light. In the present invention, the glass to be processed is first processed into a predetermined shape or size from raw glass. The processed glass is then appropriately finished so that the size of the scratch remaining on the surface is at most 10μ. The reason why the residual scratches are 10μ or less is that this level of finishing allows the hydration layer and latent scratches on the surface to be easily removed during the heat treatment process described later, and also relieves stress concentration, making it easier to remove during the ion exchange treatment process. This is because cracks are also prevented. On the other hand, the rate of temperature increase in the temperature increase and heat treatment after the polishing process is always selected within the range of 100° C./sec or less. The reason is that the heating rate is 100
This is because if the temperature exceeds .degree. C./sec, cracks occur in the ion exchange treatment and the yield decreases. Also,
The purpose of irradiating the ion exchange surface with light such as a laser is to allow the diffused ions to enter the interior and stabilize them. For example, during use of a field effect transistor, internal Na ⁺ ions are prevented from coming out to the surface and deteriorating the electrical characteristics of the device. Next, specific examples according to the present invention will be described. _SiO2 , _Al2O3 , _Na2O , _K2O , PbO, _CaO ,
Glass plates (4 x 4 x 0.05 inches) were prepared, each having a composition ratio (wt%) of MgO, B ₂ O ₃ , ZnO, TiO _2, etc., as shown in Table 1.
2000 mesh abrasive (A), 1500 mesh particle size abrasive (B), ultra-fine abrasive particle size 2000 mesh or more (C)
Each was polished to a mirror finish.

[Table] After that, each of these mirror-finished glass plates was heated to a predetermined temperature of 400 to 470°C, and maintained at the elevated temperature for 10 minutes to 1 hour for heat treatment.
KNO ₃ salt (a) at the specified temperature after this heat treatment, or 80
%KNO ₃ -20%AgNO ₃ Immersed in molten salt (b) for a certain period of time to perform ion exchange, then 10 to 14 Watt of CW-Ar was placed on the ion exchange treated glass surface.
irradiated with laser. The temperature during irradiation was 500°C, and the irradiation time was about 1 second. Table 2 summarizes the results of the glass yield, smoothness, and scratch strength after polishing, heating, and ion exchange laser irradiation, including comparative examples. The yield after laser irradiation did not decrease, and both the smoothness and scratch strength showed superior results compared to those without irradiation.

【table】

[Table] As another comparative example, when ion exchange was performed without temperature raising heat treatment after polishing, the yield was 10% higher than the yield in each example.
The front and back were inferior. Furthermore, by having the above-mentioned good smoothness, when used as a photomask, the wear of the glass can be reduced by as much as 20 to 40%, and the breakage rate can also be reduced by several percentage points. This treatment method can be applied to glass for liquid crystal televisions, glass for field effect transistors, and other optical glasses, and is a low-cost and industrially excellent treatment method.

Claims (1)

[Claims] 1. Processing the size of scratches on the glass surface to 10μ or less, heating this glass at a heating rate of 100°C/sec or less and at a temperature lower than its softening point, and ion-exchanging the heated glass, A glass surface treatment method comprising the step of irradiating an ion exchange treated surface with light.