GB2234968A

GB2234968A - Method of modifying the surface of a glass substrate

Info

Publication number: GB2234968A
Application number: GB9013187A
Authority: GB
Inventors: Takashi Tagami; Keiji Oyoshi; Shuhei Tanaka
Original assignee: Nippon Sheet Glass Co Ltd
Current assignee: Nippon Sheet Glass Co Ltd
Priority date: 1989-06-19
Filing date: 1990-06-13
Publication date: 1991-02-20
Anticipated expiration: 2010-06-13
Also published as: JPH0323238A; FR2648454A1; GB9013187D0; DE4018804A1; IT9020659A1; IT1248863B; IT9020659A0; GB2234968B; FR2648454B1; CA2018781A1

Abstract

A method of modifying the surface of a glass substrate, comprises implanting ions into the substrate and heating a portion of the glass substrate implanted with the ions with laser radiation during or after ion implantation.

Description

1 METHOD OF MODIFYINGTHE7 SURFA-E nF A GLASS SUBSTRATE The present

invention concerns a method of modifying the surface of a glass substrate using ion implantation. More particularly, it relates to a method of improving the surface to form a modified surface layer of good quality.

Methods are known for modifying the surface of a glass substrate by using an ion implantation.

For instance, a known method involves implanting phosphorus ions at an energy of about 250 KeV into a glass plate containing sodium ions, and then annealing the glass plate at 6500C, thereby bonding the implanted ion species and glass constituent elements to form a phosphosilicate glass layer inside the glass plate. Then, the method is continued by implanting nitrogen ions at an energy of about 50 KeV and applying annealing at 65011C, thereby bonding the implanted nitrogen ions and the glass constituent elements to form a silicon nitride layer (for example, see Japanese Patent Laid-Open Sho 63-222046).

However, in the conventional surface modifying method as described above, because it-is necessary to apply annealing after the ion implantation at or below the softening point temperature of the glass substrate, and because reaction between the implanted ion species and the glass constituent elements is not sufficient, the expected satisfactory surface modified layer is not obtained.

This causes a problem when trying to surface modify inexpensive glass substrates for industrial use as high quality substrates.

According to the present invention, there is provided a method of modifying the surface of a glass substrate, comprising implanting ions into the substrate and heating a portion of the glass substrate implanted with the ions with laser radiation during or after ion implantation.

Any laser beam radiation may be used so long as it can raise the temperature of the glass surface layer implanted with the ions.

For instance, in an!on implanted layer containing a great amount of Si, the inside of the glass substrate can be heated directly by using an excimer laser and an Ar laser etc. showing high absorption to Si.

1 Further, in addition to the use of laser beams of high absorption in the ion implanted layer, it is also possible to heat the!on implanted layer indirectly from the glass layer by irradiating using a C'-02 laser showing high absorption in glass.

Further, heating may be conducted through a thin film made of laserabsorbing material disposed on the glass substrate.

Any combination of the kind of the thin f ilm and the laser beam may be used so long as the thin f ilm is on the surface of the glass containing the!on implanted layer and is capable of being heated to a high temperature.

For instance, in a case where S! is deposited onto the glass surface as a thin film of laser absorbing material, excimer laser, Ar laser etc. showing good absorption in the Si film can be used as the laser.

Further, in a case where an Si02 fim is formed on the glass surface, a 002 laser showing high absorption in the SI02 film can be used.

A semiconductor film such as Si is desirably used as the thin film of laser absorbing material, because the annealing of the substrate and the crystallization of the semiconductor film can be practiced at the same time.

As methods of applying heating by way of a thin film of laser absorbing material disposed on the glass substrate, there can be exemplified:

(1) irradiating with the laser beam after forming the thin film -on the glass substrate and implanting the ions, (2) irradiating with the laser beam while forming the thin film on the ion-implanted glass substrate, (3) irradiating with the laser beam after forming the thin f ilm on the ion-implanted glass substrate, etc.

The laser beam can be irradiated in a range of directions and, for example, it may be applied to the implanted surface or the rear face of the glass substrate.

The laser beam can be irradiated at any strength and for any time, providing that a necessary portion of the!on implanted glass substrate is heated sufficiently and so long as deformation of the glass substrate is not caused. For instance, when the laser beam is irradiated in 0.

1 3 - a spot-like manner onto the substrate, heating of the necessary portion of the glass substrate is completed within a short period of time.

As the glass substrate usable in the present invention, there may be used glass substrates surh as alkali -contai nin g glass substrate, low alkali glass substrate and alkaliless glass substrate. The alkali-containing glass substrate and low alkali glass substrate are particularly preferred since they undergo a remarkable surface modifying effect when treated in accordance with the present invention.

With the present invention, since the ion implanted layer can be heated instantly and annealed by the laser beam, the necessary portion can be heated to a temperature equal to or higher than the softening point of the glass substrate and, accordingly, the implanted!on species and the glass constituent elements cause bonding, thereby forming a surface modified layer of good quality.

Particular non-limiting embodiments of the invention will now be described.

Example I

Nitrogen ions were implanted at 30 <eV at 1 x 1017 ions/cm2 into the surface of a glass substrate, thereby forming an ion implanted layer having a concentration peak at a depth of 0.06 tim fro.m the surface of the glass substrate. Subsequently, a C02 laser (at 10.6 Vm wavelength) irradiated the surface of the glass substrate. The parameters of the C02 laser were 200 I.Lm beam diameter, 45 W beam power and 1.5 m/min scanning speed.

Then, when the specimen was analysed using X-ray photoelectron spectroscopy, a 5 to 10 times greater silicon nitride concentration was measured in the specimen irradiated with the C02 12ser as compared with the specimen not irradiated with the C02 laser.

Further, a 5 to 10 times greater silicon nitride concentration was also measured compared with the specimen heat treated at 4000C after ion implantation.

It is considered that the concentration of silicon nitride has a positive correlation with the performance at preventing the diffusion of alkali metals contained in the glass substrate and it can he seen that the heating operation applied to the substrate by using the laser beam in accordance with the present invention has the effect of improving the surface property of the glass substrate so as to prevent alkali metal diffusion.

Example 2

Phosphorus ions were implanted at 100 KeV at 1 x 1017 ions/cm2 into the surface of a glass substrate, thereby forming a first ion implanted layer having a concentration peak at a depth of 0.1 gm from the surface of the glass substrate. Then, nitrogen ions were implanted at 30 KeV at 1 x 1017 ions/cm2 into the surface of the glass substrate, thereby forming a second ion implanted layer having a concentration peak at a depth of 0.06 gm from the surface of the glass substrate.

Then, a 002 laser (10.6 [Lm wavelength) irradiated the surface of the glass substrate under the same conditions as those in Example 1.

Then, when the specimen was analysed using X-ray photoelectron spectroscopy, a 2 to 3 times greater phosphosilicate concentration was measured in the first ion implanted layer and a 5 to 10 times greater silicon nitride concentration was measured in the second ion implanted layer in the specimen irradiated with the (_-02 laser as compared with the specimen not irradiated with the C02 laser.

Further, a 5 to 10 times greater silicon nitride concentration and a 2 to 3 times greater phosphosilicate concentration were also measured compared with the specimen heat treated at 4000C after ion implantation.

Example 3

Silicon ions were implanted at 60 KeV at I x 1017 ions/cM2 into the surface of a glass substrate to form an ion implanted layer having a concentration peak at a depth of 0.06 lim from the surface of the glass substrate and, thereafter, nitrogen ions were implanted at 30 KeV at 1_x 1017 ions/cm2 to form another ion implanted layer so as to overlap with the ion implanted layer just mentioned above.

Then, the surface or rear face of the glass substrate was irradiated by one pulse from an excimer laser of XeCI (308 nm C.

wavelength) at a beam intensity of 100 mj1cm2. When the specimen was analysed using X-ray photoelectron spectroscopy, a 5 to 10 times greater ion concentration was measured in the specimen irradiated with the excimer laser as compared with the specimen not irradiated with the excimer laser.

Further, a 5 to 10 times greater silicon nitride concentration was measured compared with a specimen heat treated at 4000C after ion implantation.

As has been described above, it is apparent that the present invention is applicable not only to a single modified layer implanted with one species of ion but also to a modified lamination type layer implanted with a plurality of ion species.

Example 4

Nitrogen ions were implanted at 30 KeV at 1 x 1017 ions/cm2 into the surface of a glass substrate to form an ion implanted layer having a concentration peak at a depth of 0.06 [Lm from the surface of the glass substrate. Then, an amorphous Si film of 10 nm thickness was formed on the surface of the glass substrate and the surface was irradiated by one pulse from a XeCl excimer laser (308 nm wavelength) at a beam density of 100 mj/CM2.

Subsequently, when the specimen was analysed using X-ray photoelectron spectroscopy, a 5 to 10 times greater silicon nitride concentration was measured in the specimen deposited with the amorphous Si film and irradiated with the excimer laser as compared with a specimen after ion implantation.

Further, a 5 to 10 times greater silicon nitride concentration was measured compared with a specimen heat treated at 4001C after ion implantation.

Example 5

Phosphorus ions were implanted at 100 KeV at I x 1017 ions/cm2 into the surface of a glass substrate to form a first ion implanted layer having a concentration peak at a depth of 0.1 grn from the surface of the glass substrate. Then, nitrogen ions were implanted at 30 KeV at 1 x 1017 - 6 ions/cm2 to form a second!on implanted layer having a concentration peak at a depth of 0.06 gm from the surface of the glass substrate. Subsequently, an amorphous 91 film of 10 nm thickness was formed on the surface of the glass substrate and a XeC1 excimer laser was used to irradiate the surface of the glass substrate under the same conditions as those in Example 1.

Then, when the specimen was analysed using X-ray photoelectron spectroscopy, a 2 to 3 times greater phosphosilicate concentration was measured in the f irst ion implanted layer and a 5 to 10 times greater silicon nitride concentration was measured in the second ion implanted layer in the specimen formed with the amorphous Si film and irradiated with the excimer laser as compared with a specimen after!on implantation.

Further, a 2 to 3 times greater phosphosilicate concentration and a 5 to 10 times greater silicon nitride concentration were measured compared with a specimen heat treated at 40011C after ion implantation.

Example 6

Silicon ions were implanted at 60 KeV at I x 1017 ions/cm2 into the surface of a glass substrate to form an ion implanted layer having a concentration peak at a depth of 0.06 gm from the surface of the glass substrate. Then, nitrogen ions were implanted at 30 KeV at 1 x 1017 ions/cm2 to form another ion implanted layer so as to overlap with the implanted layer just mentioned above. Subsequently, an amorphous Si film of 10 nm thickness was formed on the surface of the glass substrate and a XeCl excimer laser used to irradiate the surface of the glass substrate'under the same conditions as those in Example 4.

When the specimen was analysed using X-ray photoelectron spectroscopy, a 5 to 10 times greater silicon nitride concentration was measured in the specimen formed with the amorphous Si film and irradiated with the excimer laser, as compared with a specimen after ion implantation.

Further, a 5 to 10 times greater silicon nitride concentration was measured as compared with a specimen heat treated at 40011C after ion implantation.

A Example 7

Nitrogen ions were implanted at 30 KeV at 1 x 1017 ions/cm2 into the surface of the glass substrate to form an ion implanted layer having a concentration peak at a riepth of 0.06 gm from the surface of the glass substrate. Then, an Si02 film Of I Rm thickness was formed on the surface of the glass substrate and then irradiated with a 002 laser (10.6 jim wavelength). The parameters of the C02 laser were 200 gm beam diameter, 45 W beam power and 1.5 m/min scanning speed.

Subsequently, when the specimen was analysed using X-ray photoelectron spectroscopy, a 5 to 10 times greater silicon nitride concentration was measured in the specimen formed with the Si02 film and irradiated with the C02 laser as compared with a specimen after ion implantation.

Althouo,h the laser beam irradiates the implanted surface of the glass substrate in the above-mentioned examples, the laser beam radiation may be applied to any face such as the rear face. Further, the shape of the glass substrate may be varied.

With the present invention, because the ion implanted layer(s) of the glass substrate can be heated instantly to a high temperature without softening the entire glass substrate, bonding between the implanted ions and to each other and/or implanted ion and ions at the inside of the glass can be promoted to obtain a surface modified layer of good quality.

i 4 -a-

Claims

1. A method of modifying the surface of a glass substrate, comprising implanting ions into the substrate and heating a portion of the glass substrate implanted with the ions with laser radiation rfuring rr after!on implantation.

i

2. A method according to claim 1, further comprising applying a film of laser absorbing material onto the glass substrate before the heating using the laser radiation.

3. A method according to claim 1 or 2, wherein the temperature to which the substrate is heated is the softening point temperature or higher of the glass substrate.

4. A methori according to any one of claims 1 to 3, wherein the glass substrate is an alkali-containing glass substrate or low alkali glass substrate.

5. A method of modifying the surface nf q glass substrate, substantially as herein described.

t I; 1 i i Published 1991 at 7be Patent Office. State House. 66/71 High Holbom. IA)ndonWCIR4'IP. Further copies rnay be obtained frorn Sales Branch. Unit

6. Nine Mile Point. C%Welirffach. Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd, St MaTy Cray. Kent.