SOI-type semiconductor device and method of forming the same
First Claim
1. A silicon-on-insulator(SOI)-type semiconductor device including a lower silicon layer, a buried oxide layer, and an SOI layer comprising:
- a device region isolated by a device isolation body and the buried oxide layer, in which a source/drain region is provided for forming at least one device in the SOI layer; and
a ground region isolated from the device region by the device isolation body; and
a silicon germanium layer formed in the SOI layer, a connection portion of the silicon germanium layer extending beneath the device isolation body to connect the device region to the ground region.
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Abstract
In an SOI-type semiconductor device and a method of forming the same a semiconductor device is formed in an SOI-type substrate that is composed of a lower silicon layer, a buried oxide layer, and an SOI layer. The SOI substrate includes a device region isolated by a device isolation layer and the buried oxide layer, in which a source/drain region for forming at least one MOSFET at a body composed of the SOI layer is formed; and a ground region which is isolated from the device region by the device isolation layer and is composed of the body. A bottom portion of the device isolation layer is separated from the buried oxide layer by a connecting portion that electrically connects a body of the device region to a body of the ground region through the SOI layer. A silicon germanium layer is formed in the SOI layer, and at least partially remains at the SOI layer connecting the body of the device region to the body of the ground region in the connecting portion. Preferably, the device isolation layer is a trench-type isolation layer. The silicon germanium layer is formed at an interface between the SOI layer and the lowest portion of the SOI layer, i.e., a buried oxide layer, or is sandwiched between silicon layers that constitute the SOI layer under the SOI layer.
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Citations
16 Claims
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1. A silicon-on-insulator(SOI)-type semiconductor device including a lower silicon layer, a buried oxide layer, and an SOI layer comprising:
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a device region isolated by a device isolation body and the buried oxide layer, in which a source/drain region is provided for forming at least one device in the SOI layer; and
a ground region isolated from the device region by the device isolation body; and
a silicon germanium layer formed in the SOI layer, a connection portion of the silicon germanium layer extending beneath the device isolation body to connect the device region to the ground region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
wherein a PMOS transistor region is further included in the SOI layer;
wherein the connecting portion is formed only under the device isolation body between the NMOS transistor region and the ground region; and
wherein a transistor device formed by the NMOS transistor region and the PMOS transistor region constitutes a CMOS semiconductor device.
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11. A method of forming an SOI-type semiconductor device, comprising the steps of:
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preparing an SOI-type substrate including a lower silicon layer, a buried oxide layer, and an SOI layer wherein a silicon germanium layer is formed in a lower portion of the SOI layer; and
forming a trench isolation layer on the SOI-type substrate, wherein a bottom portion of the trench device isolation layer is located on the silicon germanium layer at a predetermined location between a device region and a ground region. - View Dependent Claims (12, 13, 14, 15, 16)
forming a shallow trench partially into the silicon germanium layer so as to separate a bottom portion of the trench from the buried oxide layer by the remaining silicon germanium layer in the predetermined location;
forming a deep trench so as to expose the buried oxide layer in the device isolation region other than in the predetermined portion; and
stacking an oxide layer using a chemical vapor deposition (CVD) technique to fill the deep and shallow trenches.
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14. The method of claim 11, after the step of forming the trench isolation layer, further comprising the steps of:
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forming an ion implanting mask, and performing an ion implantation for forming an electrode to the SOI layer of the ground region;
performing a channel ion implantation to the device region;
forming a gate electrode pattern including a gate electrode of the device region; and
performing ion implantation for forming a source/drain region in the device region, using the gate electrode pattern as an ion implanting mask.
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15. The method of claim 14, wherein the channel ion implantation and the ion implantation for forming the source/drain region are performed once for PMOS and NMOS transistor regions;
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wherein a gate electrode is patterned to both the PMOS transistor region and the NMOS transistor region.
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16. The method of claim 15, wherein the step of performing ion implantation for forming the electrode in the SOI layer of the ground region are performed at the same time as when ions are implanted into the PMOS transistor region in the steps of performing the ion implantation for forming the source/drain region.
Specification