Nitride semiconductor, semiconductor device, and manufacturing methods for the same

Abstract

A nitride semiconductor having a large low-defect region in a surface thereof, and a semiconductor device using the same are provided. Also, a manufacturing method for a nitride semiconductor comprising a layer formation step using a transverse growth technique where surface defects can easily be reduced, and a manufacturing method for a semiconductor device using the same are provided. On a substrate, a seed crystal part is formed in a stripe pattern with a buffer layer in between. Next, crystals are grown from the seed crystal part in two stages of growth conditions to form a nitride semiconductor layer. Low temperature growing parts with a trapezoid shaped cross section are formed at a growth temperature of 1030° C. in the first stage and a transverse growth is dominantly advanced at a growth temperature of 1070° C. to form a high temperature growing part between the low temperature growing parts in the second stage. Thereby, hillocks and conventional lattice defects are reduced in a surface of the nitride semiconductor layer which is above the low temperature growing part.

1 . A nitride semiconductor comprising: 
 a first seed crystal part made of a group III-V nitride semiconductor;    a second seed crystal part which is made of a group III-V nitride semiconductor and grows from the first seed crystal part to have a triangle or trapezoid shaped cross section; and    a semiconductor layer which is made of a group III-V nitride semiconductor and grows based on the second seed crystal part.    
   
   
       2 . A nitride semiconductor according to  claim 1 , wherein the first seed crystal part spreads in a direction of a crystallographic axis of <1{overscore (1)}00> to have a stripe pattern.  
   
   
       3 . A nitride semiconductor according to  claim 1 , wherein the second seed crystal part spreads to have a stripe pattern and is composed of two slant faces.  
   
   
       4 . A nitride semiconductor according to  claim 3 , wherein the two slant faces of the second seed crystal part are facets.  
   
   
       5 . A nitride semiconductor according to  claim 1 , wherein the second seed crystal part has a trapezoid shaped cross section with a ratio of (height H from the first seed crystal part to a upper base): (width W from the first seed crystal part to an outer edge on a lower base) of 1:2.  
   
   
       6 . A nitride semiconductor according to  claim 1 , wherein the group III-V nitride semiconductor is a gallium nitride (GaN) compound semiconductor.  
   
   
       7 . A semiconductor device comprising: 
 a first seed crystal part made of a group III-V nitride semiconductor;    a second seed crystal part which is made of a group III-V nitride semiconductor and grows from the first seed crystal part to have a triangle or trapezoid shaped cross section; and    a semiconductor layer which is made of a group III-V nitride semiconductor and grows based on the second seed crystal part.    
   
   
       8 . A semiconductor device according to  claim 7 , wherein the semiconductor layer comprises: 
 a plurality of connection parts which are formed by growth of the semiconductor layer in a direction different from a thickness direction thereof based on the second seed crystal part;    an active layer which is formed above the plurality of connection parts and has a current injection region; and    a current confinement part which limits the current injection region of the active layer and is located corresponding to a region between the connection parts.    
   
   
       9 . A semiconductor device according to  claim 8 , wherein the current confinement part is located corresponding to a region between the first seed crystal part and the connection part.  
   
   
       10 . A semiconductor device according to  claim 9 , wherein a sum of a distance between the first seed crystal part and the current confinement part and a distance between the current confinement part and the connection part is 4 μm or more.  
   
   
       11 . A semiconductor device according to  claim 10 , wherein a width of the current confinement part is not less than 1 μm nor more than 3 μm.  
   
   
       12 . A semiconductor device according to  claim 9 , wherein a sum of a distance between the first seed crystal part and the current confinement part and a distance between the current confinement part and the connection part is 5 μm or more.  
   
   
       13 . A semiconductor device according to  claim 12 , wherein a width of the current confinement part is not less than 1.3 μm nor more than 2.5 μm.  
   
   
       14 . A semiconductor device according to  claim 9 , wherein a distance between the first seed crystal part and the current confinement part is equal to a distance between the current confinement part and the connection part.  
   
   
       15 - 44 . (canceled)