Low temperature bonding material and bonding method

Abstract

A bonding material comprising metal particles coated with an organic substance having carbon atoms of 2 to 8, wherein the metal particles comprises first portion of 100 nm or less, and a second portion larger than 100 nm but not larger than 100 μm, each of the portions having at least peak of a particle distribution, based on a volumetric base. The disclosure is further concerned with a bonding method using the bonding material.

1 . A semiconductor device comprising:
 a semiconductor element one of the surfaces thereon having an electrode;   a ceramic substrate having wiring; and   a bonding layer for electrically bonding the electrode and the wiring,   wherein the bonding layer is a sintered layer of metal particles, wherein the metal particles comprise a first portion having a particle size of 100 nm or less, and a second portion of an aggregate having a particle size larger than 100 nm but not larger than 100 μm, said aggregate being constituted by the particles having 100 nm or less, and each of the portions having at least one peak of a particle distribution, based on a volumetric base.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein the bonding layer is made of the sintered layer of a bonding material, before sintering, comprising the metal particles, which are coated with an organic substance having carbon atoms of 2 to 8. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein the metal particles are selected from the group consisting of gold, silver and copper. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein the semiconductor element has a connecting terminal on the surface opposite to the electrode. 
     
     
         5 . The semiconductor device according to  claim 3 , wherein the wiring is constituted by copper, and the surface thereof is plated with nickel. 
     
     
         6 . The semiconductor device according to  claim 3 , wherein the connecting terminal is made of copper, and the surface thereof is plated with nickel. 
     
     
         7 . The semiconductor device according to  claim 3 , wherein the connecting terminal has a large wiring width. 
     
     
         8 . The semiconductor device according to  claim 1 , wherein a periphery of the ceramic substrate is provided with a water repellent film on the surface opposite to the surface where the electrode is formed. 
     
     
         9 . The semiconductor device according to  claim 1 , which further comprises a base plate connected with the opposite surface of the ceramic substrate where the semiconductor element is mounted by means.