Structure and fabrication method for capacitors integratible with vertical replacement gate transistors
A process and an architecture related to a vertical MOSFET device and a capacitor for use in integrated circuits. Generally, the integrated circuit structure includes a semiconductor layer with a major surface formed along a plane thereof and further including a first doped region formed in the surface. A second doped region of a different conductivity type than the first doped region is positioned over the first region. A third doped region of a different conductivity type than the second region is positioned over the second region. In one embodiment of the invention, a semiconductor device includes a first layer of semiconductor material and a first field-effect transistor having a first source/drain region formed in the first layer. A channel region of the transistor is formed over the first layer and an associated second source/drain region is formed over the channel region. The integrated circuit further includes a capacitor having a bottom plate, dielectric layer and a top capacitor plate. In an associated method of manufacture, a first device region, selected from the group consisting of the source region and a drain region of a field-effect transistor is formed on a semiconductor layer. A first field-effect transistor gate region is formed over the first device region. A capacitor comprising top and bottom layers with a dielectric layer disposed therebetween, is also formed on the semiconductor layer. In another embodiment, the capacitor layers are formed within a trench or window formed in the semiconductor layer.
1. An integrated circuit structure comprising:
a semiconductor layer having a major surface formed along a plane having first and second areas;
a first doped region of a first conductivity type in the first area of the surface;
multiple layers over the first doped region in the first area and over the second area, wherein the multiple layers have a first window therein extending to the first doped region and a second window in the second area, the second window comprising sidewall and bottom surfaces;
a second doped region of a second conductivity type in the window formed in the first area;
a third doped region of the first conductivity type over the second doped region in the first area;
a gate oxide adjacent the second doped region in the first area;
a first conductive layer with first and second electrically continuous portions, each of which is laterally disposed in the respective first and second areas, wherein the first electrically continuous portion is adjacent the gate oxide in the first area;
within the second window a second conductive layer substantially conformal with the sidewall surfaces and the bottom surfaces in the window and electrically connected to the second electrically continuous portion of the first conductive layer;
a conformal dielectric layer within the second window and over the second conductive layer; and
a third conductive layer over the dielectric layer, such that the third conductive layer, the dielectric layer and the second conductive layer form a capacitor.
2. The integrated circuit structure of claim 1 wherein the first and second electrically continuous portions of the first conductive layer are separated by a dielectric layer that separates the first and second areas.
3. The integrated circuit structure of claim 1 wherein the first and second electrically continuous portions of the first conductive layer are joined by a fourth electrically conductive layer.
4. The integrated circuit structure of claim 1 wherein an insulating layer is formed over the third conductive layer with a window formed therein to provide electrical access to the third conductive layer.
5. The integrated circuit structure of claim 4 wherein the insulating layer is silicon nitride.