US Patent 7932189 - Fabrication of silicon nanocrystal memory cell

http://www.freepatentsonline.com/7932189.html

Nanocrystal films can play an important role in enhancing the reliability of nanoscale floating gate memory cells. This patent from Freescale Semiconductor teaches a fabrication method for such films. Claim 1 reads:

1. A process of forming an electronic device comprising:

forming a first layer of discontinuous storage elements over a dielectric layer, wherein: the discontinuous storage elements have an average diameter of approximately 2 to approximately 20 nm; and

at least some of the discontinuous storage elements are silicon nanocrystals;

forming a second layer over the discontinuous storage elements and substantially all of the dielectric layer, wherein the second layer is a silicon layer having a thickness in a range of approximately 3 to approximately 9 nm;

oxidizing substantially all of the second layer; and

forming a gate electrode after oxidizing substantially all of the second layer, wherein the electronic device includes a memory cell comprising a set of the discontinuous storage elements and the gate electrode.

US Patent 7579238 - Multibit nanocrystal nonvolatile memory

http://www.freepatentsonline.com/7579238.html

Due to the discrete nature of nanocrystals they can be useful to facilitate the storage of multiple bits in semiconductor memory cells. This patent from Freescale Semiconductor teaches a variation of this technique which allows for a larger range of applied voltages making bit erasure possible without damage to the memory cell. Claim 1 reads:

1. A method for forming a multi-bit memory cell using a semiconductor substrate, comprising:

forming a first insulating layer over the semiconductor substrate;

forming a second insulating layer over the first insulating layer;

forming a layer of gate material over the second insulating layer;

patterning the gate material to leave a gate portion of the layer of gate material;

etching the second insulating layer to undercut the gate portion and leave a portion of the second insulating layer between the first insulating layer and the gate portion; and

forming nanocrystals on the first insulating layer wherein a first portion of the nanocrystals is under the gate portion on a first side of the portion of the second insulating layer and a second portion of the nanocrystals is under the gate portion on a second side of the portion of the second insulating layer, whereby the first portion of the nanocrystals are for storing a logic state of a first bit and the second portion is for storing a logic state of a second bit.

US Patent 7361567 - Nanocrystal nonvolatile memory with graded nitrogen content

http://www.freepatentsonline.com/7361567.html

The use of nanocrystals in some non-volatile memory designs has helped decrease gate leakage. However, electron trapping can be caused due to the nanocrystal layer. This patent from Freescale Semiconductor teaches using a graded nitrogen content to avoid this problem. Claim 1 reads:

1. A method for forming a semiconductor device comprising: providing a semiconductor substrate; forming a first insulating layer over a surface of the semiconductor substrate; forming a layer of nanocrystals over a surface of the first insulating layer; and forming a second insulating layer having a graded nitrogen content over the layer of nanocrystals.

US Patent 7279433 - Fabrication of boron nitride nanoparticle dielectric layer

http://www.freepatentsonline.com/7279433.html

There is a variety of interest in the use of low-k dielectric materials to improve electrical connections in electronic devices. This patent from Freescale Semiconductor teaches using boron nitride nanotubes as the material for such a dielectric. Claim 1 reads:

1. A method for forming a dielectric layer, comprising: providing a substrate; providing a first material comprising a suspension of boron nitride nanoparticles in a liquid medium; and forming a dielectric layer on the substrate from the suspension through an evaporative process.