Patent application number | Description | Published |
20120319165 | SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING SAME - Object of the invention is to reduce the on resistance between source and drain of a nitride semiconductor device. Between a nitride semiconductor layer lying between source and drain regions and a nitride semiconductor layer serving as an underlying layer, formed is a material having an electron affinity greater than that of these nitride semiconductor layers and having a lattice constant greater than that of the nitride semiconductor layer serving as an underlying layer. As a result, an electron density distribution of a channel formed below a gate insulating film and that of a two-dimensional electron gas formed in a region other than the gate portion, when a gate voltage is applied, can be made closer in the depth direction, leading to reduction in on resistance. | 12-20-2012 |
20130037868 | SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THE SAME - A semiconductor device includes: a first nitride semiconductor layer; a second nitride semiconductor layer formed over the first nitride semiconductor layer; and a gate electrode facing the second nitride semiconductor layer via a gate insulating film. Because the second nitride semiconductor layer is formed by stacking plural semiconductor layers with their Al composition ratios different from each other, the Al composition ratio of the second nitride semiconductor layer changes stepwise. The semiconductor layers forming the second nitride semiconductor layer are polarized in the same direction so that, among the semiconductor layers, a semiconductor layer nearer to the gate electrode has higher (or lower) intensity of polarization. In other words, the intensities of polarization of the semiconductor layers change with an inclination based on their distances from the gate electrode so that, at each interface between two semiconductor layers, the amount of negative charge becomes larger than that of positive charge. | 02-14-2013 |
20130069071 | SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME - Compression strains are generated at an interface between the cap layer and the barrier layer and an interface between the channel layer and the buffer layer and a tensile strain is generated at an interface between the barrier layer and the channel layer. Therefore, negative charge is higher than positive charge at the interface between the cap layer and the barrier layer and the interface between the channel layer and the buffer layer, while positive charge is higher than negative charge at the interface between the barrier layer and the channel. The channel layer has a stacked layer structure of a first layer, a second layer, and a third layer. The second layer has a higher electron affinity than those of the first layer and the third layer. | 03-21-2013 |
20140015019 | SEMICONDUCTOR DEVICE - The reliability of a field effect transistor made of a nitride semiconductor material is improved. An ohmic electrode includes a plurality of unit electrodes isolated to be separated from each other. With this configuration, an on-state current can be prevented from flowing in the unit electrodes in a y-axial direction (negative direction). Further, in the respective unit electrodes, a current density of the on-state current flowing in the y-axial direction (negative direction) can be prevented from increasing. As a result, an electromigration resistance of the ohmic electrode can be improved. | 01-16-2014 |
20140084300 | SEMICONDUCTOR DEVICE - A field effect transistor includes a substrate and a semiconductor layer provided on the substrate, wherein the semiconductor layer includes a lower barrier layer provided on the substrate, Ga-face grown, lattice relaxed, and having a composition In | 03-27-2014 |
20150076511 | SEMICONDUCTOR DEVICE - A field effect transistor includes a substrate and a semiconductor layer provided on the substrate, wherein the semiconductor layer includes a lower barrier layer provided on the substrate, Ga-face grown, lattice relaxed, and having a composition In | 03-19-2015 |
20150145004 | SEMICONDUCTOR DEVICE AND A METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE - The characteristics of a semiconductor device are improved. A semiconductor device is formed so as to have a channel layer formed over a substrate, a barrier layer, a trench penetrating through the barrier layer in an opening region, and reaching some point of the channel layer, a gate electrode arranged in the trench via a gate insulation film, and an insulation film formed over the barrier layer outside the opening region. Then, the insulation film has a lamination structure of a Si-rich silicon nitride film, and a N-rich silicon nitride film situated thereunder. Thus, the upper layer of the insulation film is set as the Si-rich silicon nitride film. This enables the improvement of the breakdown voltage, and further, enables the improvement of the etching resistance. Whereas, the lower layer of the insulation film is set as the N-rich silicon nitride film. This can suppress collapse. | 05-28-2015 |
20150221757 | SEMICONDUCTOR DEVICE - Characteristics of a semiconductor device are improved. The semiconductor device is configured to provide a trench that penetrates a barrier layer, and reaches a middle portion of a channel layer among an n+ layer, an n-type layer, a p-type layer, the channel layer, and the barrier layer which are formed above a substrate, a gate electrode arranged within the groove through a gate insulating film, and a source electrode and a drain electrode which are formed above the barrier layer on both sides of the gate electrode. The n-type layer and the drain electrode are electrically coupled to each other by a connection portion that reaches the n+ layer. The p-type layer and the source electrode are electrically coupled to each other by a connection portion that reaches the p-type layer. A diode including a p-type layer and an n-type layer is provided between the source electrode and the drain electrode, to thereby prevent the breaking of an element caused by an avalanche breakdown. | 08-06-2015 |
20150221758 | SEMICONDUCTOR DEVICE - To provide a semiconductor device having improved characteristics. The semiconductor device has, over a substrate thereof, a first buffer layer (GaN), a second buffer layer (AlGaN), a channel layer, and a barrier layer, a trench penetrating through the barrier layer and reaching the middle of the channel layer, a gate electrode placed in the trench via a gate insulating film, and a source electrode and a drain electrode formed on both sides of the gate electrode respectively. By a coupling portion in a through-hole reaching the first buffer layer, the buffer layer and the source electrode are electrically coupled to each other. Due to a two-dimensional electron gas produced in the vicinity of the interface between these two buffer layers, the semiconductor device can have an increased threshold voltage and improved normally-off characteristics. | 08-06-2015 |