Vertical semiconductor device with thinned substrate
View Patent ↗A vertical semiconductor device (e.g. a vertical power device, an IGBT device, a vertical bipolar transistor, a UMOS device or a GTO thyristor) is formed with an active semiconductor region, within which a plurality of semiconductor structures have been fabricated to form an active device, and below which at least a portion of a substrate material has been removed to isolate the active device, to expose at least one of the semiconductor structures for bottom side electrical connection and to enhance thermal dissipation. At least one of the semiconductor structures is preferably contacted by an electrode at the bottom side of the active semiconductor region.
1. An integrated circuit chip comprising:
an active semiconductor region having a plurality of fabricated semiconductor structures comprising a source, drain and channel that form a vertical semiconductor device, the active semiconductor region being exposed on a bottom side by the absence of substrate material such that the source and channel of the semiconductor structures are exposed semiconductor structures that provide the vertical semiconductor device with an electrical contact, wherein bottom surfaces of the exposed semiconductor structures are coplanar;
a bottom side electrode connected to at least one of the source or the channel; and
a handle wafer layer located above the active semiconductor region.
2. The integrated circuit chip of claim 1 , wherein:
the plurality of semiconductor structures form a plurality of vertical semiconductor devices; and
each of the plurality of vertical semiconductor devices is connected to a separate bottom side electrode.
3. The integrated circuit chip of claim 1 , wherein:
the plurality of semiconductor structures form a plurality of vertical semiconductor devices; and
at least two of the plurality of vertical semiconductor devices are connected to the bottom side electrode.
4. The integrated circuit chip of claim 1 , further comprising:
a trench region extending along a vertical side of the active semiconductor region and horizontally surrounding the active semiconductor region;
wherein the trench region electrically isolates the vertical semiconductor device on the integrated circuit chip.
5. The integrated circuit chip of claim 4 , wherein:
the vertical semiconductor device is contained within a first region of the integrated circuit chip;
the first region of the integrated circuit chip has a first thickness;
a second region of the integrated circuit chip has a second thickness that is smaller than the first thickness, and the second region contains at least one non-vertical semiconductor device; and
the trench region electrically isolates the first region from the second region.
6. The integrated circuit chip of claim 1 , wherein a vertical or horizontal dimension of at least one of the semiconductor structures has been minimized to reduce parasitic capacitance in the vertical semiconductor device.
7. The integrated circuit of claim 1 , wherein the bottom side electrode is connected to both the source and the channel.
8. The integrated circuit of claim 1 , wherein the active semiconductor region is formed in a semiconductor on insulator (SOI) wafer.
9. The integrated circuit chip of claim 1 , wherein:
the channel isolates the source from the drain;
the channel has a bottom boundary and a side boundary extending downward from a top surface of the active semiconductor region to the bottom boundary; and
the source and channel are in contact along the side boundary and are not in contact along the bottom boundary.
10. The integrated circuit chip of claim 9 , wherein:
the bottom side electrode is connected to the source; and
a second bottom side electrode is connected to the channel.
11. The integrated circuit chip of claim 9 , wherein the source and the channel are both connected to the bottom side electrode.
12. The integrated circuit chip of claim 9 , wherein:
the drain has a second bottom boundary and a second side boundary extending downward from the top surface of the active semiconductor region to the second bottom boundary; and
the drain and the channel are in contact along the second side boundary and are not in contact along the second bottom boundary.
13. The integrated circuit chip of claim 12 , wherein:
the bottom side electrode is connected to the source;
a second bottom side electrode is connected to the drain;
a third bottom side electrode is connected to the channel; and
the bottom side electrode, the second bottom side electrode and the third bottom side electrode are electrically isolated from each other.