Optical cap for semiconductor device

1. An optical cap structure for semiconductor device, said structure comprising:

a cap body having an opening;

an optical window made of glass plate sealed with said cap body to cover said opening so that an optical beam transmits through said optical window; and

a sealing member for sealing said optical window with said metal cap, said sealing member including a bismuth low-melting point glass containing no lead, an intermediate metal layer attached to said metal cap body, said intermediate metal layer being a metal capable of causing a eutectic reaction with respect to Bi contained in said low-melting point glass, and an eutectic alloy layer thus formed between said low-melting point glass and said intermediate metal layer.

2. An optical cap structure as set forth in claim 1 , wherein said intermediate metal is a plated gold, so that said optical window is sealed with the cap body by means of the eutectic alloy of Bi contained in said low-melting point glass and Au of the intermediate metal.

3. An optical cap structure as set forth in claim 1 , wherein said intermediate metal is a plated palladium, so that said optical window is sealed with the cap body by means of the eutectic alloy of Bi contained in said low-melting point glass and Pd of the intermediate metal.

4. An optical cap structure as set forth in claim 1 , wherein said intermediate metal is a Sn—Ni alloy plated layer, so that said optical window is sealed with the cap body by means of the eutectic alloy of Bi contained in said low-melting point glass and Sn—Ni alloy of the intermediate metal.

5. An optical cap structure as set forth in claim 1 , wherein said intermediate metal is a Zn—Ni alloy plated layer, so that said optical window is sealed with the cap body by means of the eutectic alloy of Bi contained in said low-melting point glass and Zn—Ni alloy of the intermediate metal.

6. An optical cap structure as set forth in claim 1 , wherein said intermediate metal is a Sn—Zn alloy plated layer, so that said optical window is sealed with the cap body by means of the eutectic alloy of Bi contained in said low-melting point glass and Sn—Zn alloy of the intermediate metal.

7. An optical cap structure as set forth in claim 1 , wherein said low-melting point glass contains not less than 30 weight % of Bi.

8. An optical cap structure as set forth in claim 1 , wherein a first surface of the intermediate metal opposite to a second surface attached to the metal cap body is a rough surface, a crystal particle size of said first surface being 0.5 μm to 1.0 μm.

9. An optical cap structure as set forth in claim 8 , wherein the intermediate metal attached to the metal cap body comprises multiple plated metal layers, at least one of the metal layers having a rough surface, a crystal particle size of which being 0.5 μm to 1.0 μm.

10. An optical device comprising:

a stem;

an optical element mounted on said stem;

a cap body secured on said stem to accommodate therein said optical element, said cap body having an opening;

an optical window made of glass plate sealed with said cap body to cover said opening so that an optical beam transmits through said optical window; and

a sealing member for sealing said optical window with said metal cap, said sealing member including a bismuth low-melting point glass containing no lead, an intermediate metal layer attached to said metal cap body, said intermediate metal layer being a metal capable of eutectic reaction with respect to Bi contained in said low-melting point glass, and a eutectic alloy layer thus formed of said low-melting point glass and said intermediate metal layer.