Semiconductor device preventing floating body effect in a peripheral region thereof and method for manufacturing the same
View Patent ↗A semiconductor device having a cell region and a peripheral region includes an silicon on insulator (SOI) substrate having a stack structure of a silicon substrate, a buried insulation layer, and a silicon layer. An epi-silicon layer is formed in the buried insulation layer of the peripheral region and connects a peripheral portion of a channel area of the silicon layer to the silicon substrate. A gate is formed on the silicon layer and junction areas are formed in the silicon layer on both sides of the gate.
1. A method for manufacturing a semiconductor device, comprising the steps of:
preparing an SOI substrate having a cell region and a peripheral region, the SOI substrate being a stack structure comprising:
a silicon substrate;
a buried insulation layer; and
a silicon layer;
forming an epi-silicon layer in the buried insulation layer of the peripheral region to connect a peripheral portion of a channel area of the silicon layer with the silicon substrate,
wherein forming the epi-silicon layer comprises:
etching the silicon layer and the buried insulation layer in the peripheral region to define a groove therein exposing the silicon substrate,
wherein defining the groove comprises:
forming a first anti-growth film on the silicon layer exposing a portion of the silicon layer in the peripheral region;
etching the exposed portion of the silicon layer to expose the buried insulation layer and define a first groove in the silicon layer;
forming a second anti-growth film on sidewalls of the first groove;
etching an exposed portion of the buried insulation layer to expose the silicon substrate and define a second groove in the buried insulation layer; and
etching the buried insulation layer having the second groove defined therein such that the second groove has a width greater than that of the first groove; and
forming a gate on the silicon layer; and
forming junction areas in the silicon layer at positions corresponding to sides of the gate.
2. The method according to claim 1 , wherein the epi-silicon layer is formed such that at least a portion of the epi-silicon layer overlaps the peripheral portion of the channel area of the silicon layer.
3. The method according to claim 1 , wherein the first anti-growth film comprises a nitride layer and the second anti-growth film comprises a nitride layer.
4. The method according to claim 1 , wherein the first anti-growth film is formed to a thickness in the range of 30˜100 Å and the second anti-growth film is formed to a thickness in the range of 30˜100 Å.
5. The method according to claim 1 , wherein the step of etching the buried insulation layer having the second groove defined therein is implemented through isotropic etching.
6. The method according to claim 5 , wherein the isotropic etching comprises a wet cleaning process.
7. The method according to claim 1 , wherein the step of growing the epi-silicon layer comprises a selective epitaxial growth process.
8. The method according to claim 1 , further comprising the step of:
after the step of growing the epi-silicon layer, removing the epi-silicon layer through a CMP process until the silicon layer is exposed.
9. The method according to claim 1 , further comprising the step of:
after the step of growing the epi-silicon layer and before the step of forming the gate, forming an anti-growth film on the buried insulation layer to delimit an active area in the silicon layer, wherein the peripheral portion of the channel area of the silicon layer is connected with the epi-silicon layer.
10. The method according to claim 1 , wherein the junction areas are formed to be connected to the buried insulation layer.