Trench gate NMOS transistor and trench gate PMOS transistor monolithically integrated in same semiconductor die
A semiconductor die includes: a silicon substrate; a trench gate NMOS transistor formed in a first device region of the silicon substrate; a trench gate PMOS transistor formed in a second device region of the silicon substrate and electrically connected to the trench gate NMOS transistor; and an isolation structure interposed between the first device region and the second device region. Methods of monolithically integrating the trench gate NMOS transistor and the trench gate PMOS transistor in the same semiconductor die are also described.
1 . A semiconductor die, comprising:
a silicon substrate;
a trench gate NMOS transistor formed in a first device region of the silicon substrate;
a trench gate PMOS transistor formed in a second device region of the silicon substrate and electrically connected to the trench gate NMOS transistor; and
an isolation structure interposed between the first device region and the second device region,
wherein the trench gate PMOS transistor comprises:
a p-type drift region in the second device region;
a plurality of first stripe-shaped gate trenches extending from a first main surface of the silicon substrate and terminating at a depth in the p-type drift region, each of the first stripe-shaped gate trenches having a first sidewall and a second sidewall opposite the first sidewall;
a gate electrode in each of the first stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a gate dielectric;
an n-type body region at the first sidewall of each of the first stripe-shaped gate trenches;
a p-type source region arranged above the n-type body region at the first sidewall of each of the first stripe-shaped gate trenches; and
a p-type drain region arranged closer to the second sidewall of each of the first stripe-shaped gate trenches than the first sidewall.
2 . The semiconductor die of claim 1 , wherein the trench gate NMOS transistor is a high-side switch device or a low-side switch device of a power converter circuit, and wherein the trench gate PMOS transistor forms part of a stage of a gate driver for the trench gate NMOS transistor.
3 . The semiconductor die of claim 1 , wherein the trench gate PMOS transistor and the trench gate NMOS transistor form a stage of a gate driver, and wherein at least one additional stage of the gate driver is not integrated in the semiconductor die.
4 . The semiconductor die of claim 1 , wherein the gate dielectric is thicker at the second sidewall of each of the first stripe-shaped gate trenches than at the first sidewall.
5 . The semiconductor die of claim 1 , wherein for each of the first stripe-shaped gate trenches, the gate electrode laterally terminates closer to the first sidewall than to the second sidewall such that the gate electrode is laterally separated from the p-type drain region at the second sidewall by a larger distance than from the p-type source region at the first sidewall.
6 . The semiconductor die of claim 1 , wherein the first main surface of the silicon substrate is recessed adjacent the second sidewall of the first stripe-shaped gate trenches such that the p-type drain regions are arranged deeper in the silicon substrate than the gate electrodes.
7 . The semiconductor die of claim 1 , wherein the trench gate PMOS transistor further comprises:
a field electrode below the gate electrode in each of the first stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a field dielectric.
8 . The semiconductor die of claim 1 , wherein the p-type drain region arranged at the second sidewall of each of the first stripe-shaped gate trenches is electrically connected to a gate terminal of the trench gate NMOS transistor.
9 . The semiconductor die of claim 8 , wherein the p-type source region arranged at the first sidewall of each of the first stripe-shaped gate trenches is electrically connected to a positive DC voltage input terminal of the semiconductor die.
10 . The semiconductor die of claim 1 , wherein the trench gate NMOS transistor comprises:
an n-type drift region in the first device region;
a plurality of second stripe-shaped gate trenches extending from the first main surface of the silicon substrate and terminating at a depth in the n-type drift region;
a gate electrode in each of the second stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a gate dielectric;
a p-type body region at a first sidewall of each of the second stripe-shaped gate trenches;
an n-type source region arranged above the p-type body region at the first sidewall of each of the second stripe-shaped gate trenches; and
an n-type drain region.
11 . The semiconductor die of claim 10 , wherein the n-type drain region is arranged at a second sidewall of each of the second stripe-shaped gate trenches opposite the first sidewall.
12 . The semiconductor die of claim 10 , wherein the n-type drain region is arranged at a second main surface of the silicon substrate opposite the first main surface.
13 . The semiconductor die of claim 10 , wherein the p-type drain regions of the trench gate PMOS transistor are electrically connected to the gate electrodes in the second stripe-shaped gate trenches.
14 . The semiconductor die of claim 1 , wherein the trench gate NMOS transistor is a power NMOSFET (n-channel metal-oxide-semiconductor field-effect transistor).
15 . A method of fabricating a semiconductor die, the method comprising:
forming a trench gate NMOS transistor in a first device region of a silicon substrate;
forming a trench gate PMOS transistor in a second device region of the silicon substrate;
forming an isolation structure between the first device region and the second device region; and
electrically connecting the trench gate PMOS transistor to the trench gate NMOS transistor,
wherein forming the trench gate PMOS transistor comprises:
forming a p-type drift region in the second device region;
forming a plurality of first stripe-shaped gate trenches that extend from a first main surface of the silicon substrate and terminate at a depth in the p-type drift region, each of the first stripe-shaped gate trenches having a first sidewall and a second sidewall opposite the first sidewall;
forming a gate electrode in each of the first stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a gate dielectric;
forming an n-type body region at the first sidewall of each of the first stripe-shaped gate trenches;
forming a p-type source region above the n-type body region at the first sidewall of each of the first stripe-shaped gate trenches; and
forming a p-type drain region closer to the second sidewall of each of the first stripe-shaped gate trenches than the first sidewall.
16 . The method of claim 15 , wherein forming the trench gate NMOS transistor in the first device region comprises:
forming an n-type drift region in the first device region;
forming a plurality of second stripe-shaped gate trenches that extend from the first main surface of the silicon substrate and terminate at a depth in the n-type drift region;
forming a gate electrode in each of the second stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a gate dielectric;
forming a p-type body region at a first sidewall and a second sidewall of each of the second stripe-shaped gate trenches;
forming an n-type source region above the p-type body region at the first sidewall and the second sidewall of each of the second stripe-shaped gate trenches; and
forming an n-type drain region at a second main surface of the silicon substrate opposite the first main surface.
17 . The method of claim 16 , wherein the second sidewall of adjacent ones of the first stripe-shaped gate trenches face one another, and wherein forming the p-type drain region at the second sidewall of each of the first stripe-shaped gate trenches comprises:
etching a recess into the first main surface of the silicon substrate such that the silicon substrate has a recessed part between the second sidewall of adjacent ones of the first stripe-shaped gate trenches; and
implanting a p-type dopant species into the recessed part of the silicon substrate.
18 . The method of claim 17 , wherein the second stripe-shaped gate trenches extend deeper into the semiconductor substrate than the first stripe-shaped gate trenches, wherein a field electrode is arranged below the gate electrode in each of the second stripe-shaped gate trenches and dielectrically insulated from the silicon substrate by a field dielectric, and wherein the first stripe-shaped gate trenches are devoid of a field electrode.
19 . A semiconductor die, comprising:
a silicon substrate;
a trench gate NMOS transistor formed in a first device region of the silicon substrate;
a trench gate PMOS transistor formed in a second device region of the silicon substrate and electrically connected to the trench gate NMOS transistor; and
an isolation structure interposed between the first device region and the second device region,
wherein the trench gate PMOS transistor and the trench gate NMOS transistor form a stage of a gate driver,
wherein at least one additional stage of the gate driver is not integrated in the semiconductor die.