Method of machining glass substrate and method of fabricating high-frequency circuit

Abstract

A method of machining a glass substrate using a laser, in which a low-permittivity, low-dielectric-loss glass substrate, capable of coping with mass production, is made applicable as the substrate of a high-frequency circuit intended in particular for microwave and millimeter-wave bands. For that purpose, a glass substrate is provided in which the amount of air bubbles in glass is arbitrarily controlled to improve the workability of the substrate. Then, the glass substrate is machined by being irradiated with a pulsed laser a plurality of times, thereby improving the machining shape of the glass substrate. Since glass substrates which are typically difficult to machine can be easily applied to the fabrication of high-frequency circuits, it becomes possible to supply high-performance circuits and apparatuses widely to the public.

What is claimed is:  
     
         1 . A glass substrate machining method comprising the steps of: 
 a) preparing a glass substrate in which an amount of air bubbles in said glass substrate is controlled to improve the workability of said glass substrate;    b) machining said glass substrate by using a laser to make a hole or a groove in said glass substrate.    
     
     
         2 . A glass substrate machining method comprising the steps of: 
 a) preparing a glass substrate in which an amount of air bubbles in said glass substrate is controlled to improve the workability of said glass substrate;    b) forming a thin insulator on a surface of said glass substrate;    c) machining said glass substrate by using a laser to make a hole or a groove in said glass substrate.    
     
     
         3 . The glass substrate machining method according to  claim 2 , wherein said thin insulator on said glass surface is glass formed by coating said surface.  
     
     
         4 . The glass substrate machining method according to  claim 2 , wherein said thin insulator formed on said glass surface is an organic insulator film.  
     
     
         5 . The glass substrate machining method according to  claim 4 , wherein said thin organic insulator on said glass surface is formed by coating said surface.  
     
     
         6 . The glass substrate machining method according to  claim 4 , wherein said thin insulator on said glass surface is united with said glass substrate into a sheet form by lamination therewith.  
     
     
         7 . The glass substrate machining method according to  claim 1 , wherein a CO 2  laser is used to perform the laser machining.  
     
     
         8 . The glass substrate machining method according to  claim 2 , wherein a CO 2  laser is used to perform the laser machining.  
     
     
         9 . A glass substrate machining method comprising the steps of: 
 machining a glass substrate by using a laser;    controlling an amount of air bubbles in a glass substrate so that said glass substrate, after said laser machining, has a large surface area on the machined surface due to bubble traces in glass; and    forming a metal film through simple electroless plating, to improve heat radiation property of the metal-film-formed portion.    
     
     
         10 . The glass substrate machining method according to  claim 9 , wherein a CO 2  laser is used to perform the laser machining.  
     
     
         11 . In a method of machining a glass substrate by application of laser irradiation to said glass substrate from a laser, the improvement wherein: 
 said glass substrate is a glass substrate having therein discrete air bubbles; and    said laser is a CO 2  laser or an excimer laser.    
     
     
         12 . A machined glass product made by the process of  claim 11 .  
     
     
         13 . The method of  claim 11 , wherein said glass substrate is provided on a surface thereof with a thin layer selected from the group consisting of a thin insulator layer and a thin metal layer.  
     
     
         14 . The method of  claim 13 , wherein said thin layer is an insulator layer and has a thickness of about 10-70 μm.  
     
     
         15 . The method of  claim 14 , wherein said thin insulator layer is an organic film formed by lamination or an inorganic substance applied by spin coating.  
     
     
         16 . The method of  claim 13 , wherein said thin layer is a metal film having a thickness of approximately 10 μm or less.  
     
     
         17 . The method of  claim 11 , wherein said laser irradiation is carried out in a plurality of stages.  
     
     
         18 . The method of  claim 17 , wherein a first stage of laser irradiation is carried out at a first pulse width, and a second stage of said laser irradiation is carried out with a pulse width greater than said first pulse width.  
     
     
         19 . The method of  claim 18 , wherein said second stage of laser irradiation is performed a plurality of times.  
     
     
         20 . The method of  claim 18 , wherein said plural stages of laser irradiation are carried out with the diameter of the laser beam remaining substantially unchanged.  
     
     
         21 . The method of  claim 20 , wherein the pulse width of laser irradiation between said first stage and said second stage is changed.  
     
     
         22 . The method of  claim 18 , wherein the pulse width of laser irradiation between said first stage and said second stage is changed.  
     
     
         23 . The method of  claim 18 , wherein said laser irradiation is applied to form a through-hole in said substrate, and the focus of the laser in the depth direction of the through hole is changed from the first stage to the second stage.  
     
     
         24 . The method of  claim 11 , wherein the bubble diameter of the discrete air bubbles is greater than or equal to 50 μm.