Method for forming a device comprising a bipolar transistor
A device including a transistor is fabricated by forming a first part of a first region of the transistor through the implantation of dopants through a first opening. The second region of the transistor is then formed in the first opening by epitaxy.
1. A method for forming a device comprising a bipolar transistor, comprising:
forming an isolating trench in a semiconductor substrate;
implanting dopants to form a primary part of a collector region of the bipolar transistor buried in the semiconductor substrate below the isolating trench;
forming a first opening in the isolating trench which extends through the isolating trench to reach said semiconductor substrate;
implanting dopants through said first opening to form a secondary part of the collector region of the bipolar transistor extending over said primary part; and
epitaxially growing a base region of the bipolar transistor in the first opening and laterally surrounded by said isolating trench.
2. The method according to claim 1 , further comprising:
forming an emitter region of the bipolar transistor on the base region; and
forming an insulating spacer on each lateral surface surfaces of the emitter region.
3. The method according to claim 2 , wherein a width of each insulating spacer is greater than about 40 nm.
4. The method according to claim 2 , further comprising:
forming a stack of at least one isolating layer on the base region; and
forming a second opening in the stack;
wherein forming the emitter region comprises epitaxially growing said emitter region in the second opening.
5. The method according to claim 4 , further comprising removing the stack and wherein forming the insulating spacer comprises forming spacers on each lateral surface of the emitter region.
6. The method according to claim 5 , wherein a width of each spacer is greater than about 40 nm.
7. The method according to claim 1 , further comprising forming a deep trench isolation surrounding the bipolar transistor, said deep trench isolation having a depth in the semiconductor substrate which is greater than a depth of the isolating trench.
8. The method according to claim 1 , wherein said semiconductor substrate is made of a non-doped semiconductor material.
9. The method according to claim 8 , wherein portions of the non-doped semiconductor material laterally surround the secondary part of the collector.
10. A method for forming a device comprising a bipolar transistor, comprising:
forming an isolating trench in a semiconductor substrate;
implanting dopants to form a primary part of a collector region of the bipolar transistor buried in the semiconductor substrate below the isolating trench;
forming a first opening in the isolating trench which extends through the isolating trench to reach said semiconductor substrate;
epitaxially growing a base region of the bipolar transistor in the first opening and laterally surrounded by said isolating trench;
forming a stack of at least one isolating layer on the base region;
forming a second opening extending through the stack;
implanting dopants through said second opening to form a secondary part of the collector region of the bipolar transistor in the semiconductor substrate between said primary part and the base region; and
epitaxially growing an emitter region of the bipolar transistor in said second opening.
11. The method of claim 10 , further comprising removing the stack.
12. The method of claim 11 , further comprising forming an insulating spacer on each lateral surface of the emitter region.
13. The method of claim 12 , wherein a width of each insulating spacer is greater than about 40 nm.
14. The method of claim 10 , further comprising forming a deep trench isolation surrounding the bipolar transistor, said deep trench isolation having a depth in the semiconductor substrate which is greater than a depth of the isolating trench.
15. The method of claim 10 , wherein said semiconductor substrate is made of a non-doped semiconductor material.
16. The method according to claim 15 , wherein portions of the non-doped semiconductor material laterally surround the secondary part of the collector.