Abstract:
A manufacturing method of a junction field effect transistor includes the steps of: (a) forming an n+-type source layer on a surface of an n−-type drift layer formed on an n+-type SiC substrate; (b) forming a plurality of shallow trenches disposed at predetermined intervals by etching the surface of the n−-type drift layer with a silicon oxide film formed on the n−-type drift layer used as a mask; (c) forming an n-type counter dope layer by doping the n−-type drift layer below each of the shallow trenches with nitrogen by using a vertical ion implantation method; (d) forming a sidewall spacer on each sidewall of the silicon oxide film and the shallow trenches; and (e) forming a p-type gate layer by doping the n−-type drift layer below each of shallow trenches with aluminum by using the vertical ion implantation method.
Abstract:
In general, in a semiconductor active element such as a normally-off JFET based on SiC in which an impurity diffusion speed is significantly lower than in silicon, gate regions are formed through ion implantation into the side walls of trenches formed in source regions. However, to ensure the performance of the JFET, it is necessary to control the area between the gate regions thereof with high precision. Besides, there is such a problem that, since a heavily doped PN junction is formed by forming the gate regions in the source regions, an increase in junction current cannot be avoided. The present invention provides a normally-off power JFET and a manufacturing method thereof and forms the gate regions according to a multi-epitaxial method which repeats a process including epitaxial growth, ion implantation, and activation annealing a plurality of times.
Abstract:
A normally-off type silicon carbide junction FET has a problem that the gate thereof is not easy to use due to inferiority in the characteristics of it. This problem occurs because in order to achieve normally-off, the gate voltage should be off at 0V and at the same time, the ON-state gate voltage should be suppressed to about 2.5V to prevent the passage of an electric current through a pn junction between gate and source. Accordingly, a range from the threshold voltage to the ON-state gate voltage is only from about 1 V to 2V and it is difficult to control the gate voltage. Provided in the present invention is an electronic circuit device obtained by coupling, to a gate of a normally-off type silicon carbide junction FET, an element having a capacitance equal to or a little smaller than the gate capacitance of the junction FET.
Abstract:
A manufacturing method of a junction field effect transistor includes the steps of: (a) forming an n+-type source layer on a surface of an n−-type drift layer formed on an n+-type SiC substrate; (b) forming a plurality of shallow trenches disposed at predetermined intervals by etching the surface of the n−-type drift layer with a silicon oxide film formed on the n−-type drift layer used as a mask; (c) forming an n-type counter dope layer by doping the n−-type drift layer below each of the shallow trenches with nitrogen by using a vertical ion implantation method; (d) forming a sidewall spacer on each sidewall of the silicon oxide film and the shallow trenches; and (e) forming a p-type gate layer by doping the n−-type drift layer below each of shallow trenches with aluminum by using the vertical ion implantation method.