Method and structures for dual depth oxygen layers in silicon-on-insulator processes

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer, wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate, wherein the first region includes a first semiconductor device, and wherein the second region includes a second semiconductor device, wherein the second semiconductor device is a resistor structure;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench touches the buried oxide layer, wherein the second trench electrically isolates the second region within the substrate from a third region within the substrate, and wherein the third region includes a third semiconductor device.

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer, wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate, wherein the first region includes a first semiconductor device, and wherein the second region includes a second semiconductor device, wherein the second semiconductor device is a decoupling capacitor;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench touches the buried oxide layer, wherein the second trench electrically isolates the second region within the substrate from a third region within the substrate, and wherein the third region includes a third semiconductor device.

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer, wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate, wherein the first region includes a first semiconductor device, and wherein the second region includes a second semiconductor device, wherein the second semiconductor device is a bipolar transistor;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench touches the buried oxide layer, wherein the second trench electrically isolates the second region within the substrate from a third region within the substrate, and wherein the third region includes a third semiconductor device.

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer, wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate, wherein the first region includes a first semiconductor device, and wherein the second region includes a second semiconductor device, wherein the second semiconductor device is a polysilicon bounded diode structure;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench touches the buried oxide layer, wherein the second trench electrically isolates the second region within the substrate from a third region within the substrate, and wherein the third region includes a third semiconductor device.

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate;
• single step shallow trench isolation regions touching the buried oxide layer at the first depth for isolating devices formed between the first depth and the first surface;
• and
• dual step shallow trench isolation regions selectively touching the buried oxide layer at the second depth for isolating a group of devices formed between the second depth and the first surface, wherein the group of devices includes at least one device.

A semiconductor structure comprising:

• a substrate comprising a first surface;
• a continuous, depth-varying buried oxide layer within the substrate;
• a first trench between the first surface and the buried oxide layer;
• and
• an external trench within the substrate, wherein a first region within the substrate is electrically isolated by the external trench, the first trench, and the buried oxide layer, wherein the external trench is external to the first region and bounds a side of the first region, wherein the external trench touches an end surface of the buried oxide layer, and wherein the first region is electrically isolated from a second region within the substrate.

A semiconductor structure comprising:

• a substrate having a first surface;
• a continuous buried oxide layer within the substrate, wherein a first portion of the buried oxide layer is disposed at a first depth relative to a point on the first surface, and wherein a second portion of the buried oxide layer is disposed at a second depth relative to the point on the first surface;
• a first semiconductor region between the first surface and the first depth of the buried oxide layer, wherein the first semiconductor region touches the first surface and touches the buried oxide layer at the first depth, and wherein the first semiconductor region includes P+ semiconductor material;
• a second semiconductor region between the first surface and the second depth of the buried oxide layer, wherein the second semiconductor region touches the first surface and does not touch the buried oxide layer, and wherein the second semiconductor region includes N+ semiconductor material;
• a gate structure on the top surface, laterally between the first semiconductor region and the second semiconductor region;
• and
• a third semiconductor region between the first surface and the buried oxide layer, wherein the third semiconductor region is continuously distributed between the first surface and the buried oxide layer, wherein the third semiconductor region touches the buried oxide layer at the second depth, the first semiconductor region, the second semiconductor region, and the gate structure, and wherein the third semiconductor region includes N− semiconductor material.

A semiconductor structure comprising:

• a substrate having a first surface;
• a continuous buried oxide layer within the substrate, wherein a first portion of the buried oxide layer is disposed at a first depth relative to a point on the first surface, and wherein a second portion of the buried oxide layer is disposed at a second depth relative to the point on the first surface;
• a first semiconductor region between the first surface and the first depth of the buried oxide layer, wherein the first semiconductor region touches the first surface and touches the buried oxide layer at the first depth, and wherein the first semiconductor region includes N+ semiconductor material;
• a second semiconductor region between the first surface and the second depth of the buried oxide layer, wherein the second semiconductor region touches the first surface and does not touch the buried oxide layer, and wherein the second semiconductor region includes P+ semiconductor material;
• a gate structure on the top surface, laterally between the first semiconductor region and the second semiconductor region;
• and
• a third semiconductor region between the first surface and the buried oxide layer, wherein the third semiconductor region is continuously distributed between the first surface and the buried oxide layer, wherein the third semiconductor region touches the buried oxide layer at the second depth, the first semiconductor region, the second semiconductor region, and the gate structure, and wherein the third semiconductor region includes N− semiconductor material.

A semiconductor structure comprising:

• a substrate having a first surface;
• a continuous buried oxide layer within the substrate, wherein a first portion of the buried oxide layer is disposed at a first depth relative to a point on the first surface, and wherein a second portion of the buried oxide layer is disposed at a second depth relative to the point on the first surface;
• a first semiconductor region between the first surface and the first depth of the buried oxide layer, wherein the first semiconductor region touches the first surface and touches the buried oxide layer at the first depth;
• a second semiconductor region between the first surface and the second depth of the buried oxide layer, wherein the second semiconductor region touches the first surface and does not touch the buried oxide layer, and wherein there is no gate structure on the top surface laterally between the first semiconductor region and the second semiconductor region;
• and
• a third semiconductor region between the first surface and the buried oxide layer, wherein the third semiconductor region is continuously distributed between the first surface and the buried oxide layer, and wherein the third semiconductor region touches the buried oxide layer at the second depth, the first semiconductor region, and the second semiconductor region.

A semiconductor structure, comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench does not touch the buried oxide layer;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench does not touch the buried oxide layer.

A semiconductor structure, comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer, and wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate;
• and
• a second trench between the first surface and the buried oxide layer at the second depth, wherein the second trench does not touch the buried oxide layer.

A semiconductor structure, comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein the first trench touches the buried oxide layer;
• and
• a second trench between the first surface and the buried oxide layer at the second depth;
• wherein the second trench touches the buried oxide layer, wherein the first trench electrically isolates a first region within the substrate from a second region within the substrate, and wherein the second trench electrically isolates the second region within the substrate from a third region within the substrate.

A semiconductor structure, comprising:

• a substrate comprising a first surface;
• a continuous buried oxide layer disposed at a first depth and at a second depth within the substrate, wherein the first depth and the second depth are unequal;
• a first trench between the first surface and the buried oxide layer at the first depth, wherein a sidewall of the first trench is not perpendicular to the first surface;
• and
• a second trench between the first surface and the buried oxide layer at the second depth.