Patent ID: 9418852
Filing Date: 2016-08-16
CPC Classification: H01L

Claim Text:
1. A method of manufacturing a semiconductor device comprising steps of: forming a front surface structure of a semiconductor element on a first principal surface of a semiconductor substrate; grinding a second principal surface of the semiconductor substrate opposed to the first principal surface down to a predetermined thickness; forming an ion injection layer in the second principal surface side of the semiconductor substrate that has the predetermined thickness, wherein the ion injection layer is a pn continued layer including a p type impurity layer containing injected p type impurities and an n type impurity layer containing injected n type impurities, the n type impurity layer being formed after the p type impurity layer and deeper than the p type impurity layer as viewed from the second principal surface; and activating the ion injection layer by means of a laser annealing process; wherein the step of activating the ion injection layer is conducted by using a plurality of laser emission devices, each of the laser emission devices emitting laser light with a predetermined repeating frequency and a predetermined pulse width, and repeating a laser light emission procedure in a first period of time determined from the predetermined repeating frequency, the procedure including: emission of a first laser light pulse from a first laser emission device of the plurality of laser emission devices, emission of a second light pulse from a second laser emission device at an end of the first laser light pulse, emission of a third light pulse from a third laser emission device at an end of the second laser light pulse, and successive emission of n-th laser light pulse from an n-th laser emission device at an end of the (n−1)-th laser light pulse, followed by emission of the first laser light pulse from the first laser emission device at an end of the n-th laser light pulse, wherein n is a positive integer; the repeating of the laser light emission procedure forming laser light with a waveform of substantially continuous wave laser light, which irradiates the ion injection layer to activate the ion injection layer, wherein the predetermined pulse width is in a range of 1 μs to 50 μs, the laser light pulses irradiate the ion injection layer over a duration of a multiple of a first period of time corresponding to the predetermined repeating frequency; subsequently, the irradiation of laser light pulses is stopped during a second period of time; and the irradiation of laser light pulses is conducted again over the duration of the multiple of the first period of time; the procedure consisting of the irradiation over the duration of the multiple of the first period of time and the stop during the second period of time being repeated, and a duration of the second period of time is at least 100 ms.