Silica glass and its manufacturing method

A method for manufacturing a silica glass that is substantially free of chlorine, comprising the steps of:

• separately expelling a silicon tetrafluoride gas, a combustion gas, and a combustible gas from a burner made of silica glass, the flow velocity of the silicon tetrafluoride gas being within the range of about 9 slm/cm2 to about 20 slm/cm2;
• producing minute silica glass particles by reacting the silicon tetrafluoride gas with water produced by a reaction of the combustion gas with the combustible gas;
• depositing the minute silica glass particles on a target;
• and
• producing the silica glass by fusing and vitrifying the minute silica glass particles deposited on the target.

A method for manufacturing a silica glass, comprising the steps of:

• expelling a combustion gas, a combustible gas, and a material gas including a silicon tetrafluoride gas separately from a burner, the flow velocity of the silicon tetrafluoride gas included in the material gas being within the range of about 9 slm/cm2 to about 20 slm/cm2;
• reacting the combustible gas with the combustion gas to produce water;
• reacting the silicon tetrafluoride gas with the water to produce and deposit minute silica particles on a target;
• and
• fusing and vitrifying the minute silica particles deposited on the target to produce the silica glass.