power diode

Abstract

A power diode (1), comprising a semiconductor body (10) coupled to an anode metallization (11) and a cathode metallization (12) of the power diode (1), wherein the semiconductor body (10) has a drift region (100) of a first conductivity type and an anode region (101) of a second conductivity type, wherein the anode region (101) comprises: - a contact zone (1011) arranged in contact with the anode metallization (11); - a field stop zone (1012) arranged below the contact zone (1011); - a body zone (1013) arranged below the field stop zone (1012) and above the drift region (100); wherein an electrically activated dopant concentration of the anode region (101) has a profile along a vertical direction (Z) according to which: - a first maximum (31) is present in the contact zone (1011); - a second maximum (32) is present in the field stop zone (1012);and- the dopant concentration decreases continuously from the first maximum (31) to a local minimum (33) and increases continuously from the local minimum (33) to the second maximum (32), the second maximum (32) being in the range from 70% to 130% of the first maximum (31); wherein, according to the profile, the dopant concentration decreases continuously from the second maximum (32) to an inflection point (34) at which the rate of change of the dopant concentration with respect to the vertical direction (Z) has a local maximum, and wherein, during a blocking state of the power diode (1), the electric field ends below the inflection point (34);

Claims

[1] Power diode (1), comprising a semiconductor body (10) coupled to an anode metallization (11) and a cathode metallization (12) of the power diode (1), wherein the semiconductor body (10) has a drift region (100) of a first conductivity type and an anode region (101) of a second conductivity type, wherein the anode region (101) comprises: - a contact zone (1011) arranged in contact with the anode metallization (11); - a field stop zone (1012) arranged below the contact zone (1011); - a body zone (1013) arranged below the field stop zone (1012) and above the drift region (100); wherein an electrically activated dopant concentration of the anode region (101) along a vertical direction (Z) has a profile according to which: - a first maximum (31) is present in the contact zone (1011); - a second maximum (32) is present in the field stop zone (1012); and - the dopant concentration decreases continuously from the first maximum (31) to a local minimum (33) and increases continuously from the local minimum (33) to the second maximum (32), the second maximum (32) being in the range from 70% to 130% of the first maximum (31); wherein, according to the profile, the dopant concentration decreases continuously from the second maximum (32) to an inflection point (34) at which the rate of change of the dopant concentration with respect to the vertical direction (Z) has a local maximum, and wherein during a blocking state of the power diode (1) the electric field ends below the inflection point (34). [2] Power diode (1) according to claim 1, wherein the second maximum (32) is an absolute maximum of the dopant concentration of the anode region (101). [3] Power diode (1) according to one of the preceding claims, wherein the local minimum (33) is in the range of 10% to 50% of the first maximum (31). [4] Power diode (1) according to one of the preceding claims, wherein the electrically activated dopant concentration at both the first maximum (31) and the second maximum (32) is greater than 10 17 cm -3 is. [5] Power diode (1) according to one of the preceding claims, wherein the maximum electrically activated dopant concentration in the body zone (1013) is in the range of 1 / 50 to 1 / 5 of the electrically activated dopant concentration present at any one of the first maximum (31) and the second maximum (32). [6] Power diode (1) according to one of the preceding claims, wherein at least in the contact zone (1011) and the field stop zone (1012) an electrical conductivity is proportional to the electrically activated dopant concentration. [7] Power diode (1) according to one of the preceding claims, wherein according to the profile the dopant concentration decreases continuously from the inflection point (34) through the entire body zone (1013) to a junction (1010) formed between the body zone (1013) and the drift region (100). [8] Power diode (1) according to one of the preceding claims, wherein the anode region (101) has five equal parts along the vertical direction (Z), wherein both the first maximum (31) and the second maximum (32) are positioned in the uppermost equal part. [9] Power diode (1) according to one of the preceding claims, wherein both the first maximum (31) and the second maximum (32) are positioned at a distance of 2000 nm from the anode metallization (11), measured from a transition (111) between the contact zone (1011) and the anode metallization (11) along the vertical direction (Z). [10] Power diode (1) according to one of the preceding claims, wherein - the total extension of the anode region (101) in the vertical direction amounts to no more than 20% of the total extension of the drift region (100) in the vertical direction (Z); and / or wherein - the total extension of the anode region (101) in the vertical direction (Z) lies within the range from 500 nm to 15000 nm; and / or wherein - the total extension of the drift region (100) in the vertical direction (Z) lies within the range of 10 µm to 1000 µm. - the power diode (1) is implemented in a wafer having a thickness in the vertical direction (Z) within the range of 10 µm to 1000 µm. [11] Power diode (1) according to one of the preceding claims, wherein the profile in the contact zone (1011) and in the field stop zone (1012) is an implantation profile. [12] Power diode (1) according to claim 11, wherein a dose for the contact zone (1011) and for the field stop zone (1012) is less than 2*10 13 cm -2 is. [13] Power diode (1) according to one of the preceding claims, wherein a dose for the body zone (1013) is less than 1*10 13 cm -2 is. [14] Power diode (1) according to one of the preceding claims, wherein the profile in the body zone (1013) is a diffusion profile. [15] Power diode (1) according to one of the preceding claims, wherein a distance between the second maximum (32) and a peak of the electric field during a blocking state of the power diode (1) amounts to at least 500 nm. [16] Power diode (1) according to one of the preceding claims, wherein the drift region (100) is designed for a blocking voltage of at least 500 V. [17] Power diode (1) according to one of the preceding claims, wherein the semiconductor body (10) further comprises a cathode region (102) of the first conductivity type, wherein the drift region (100) is coupled to the cathode metallization (12) by means of the cathode region (102). [18] Method (2) wherein a power diode (1) is manufactured according to one of claims 1 to 17, comprising: - providing (20) the semiconductor body (10) with the drift region (100) of the first conductivity type; - producing (21) the anode region (101) of the second conductivity type in the semiconductor body (10); - Providing (22) the electrically activated dopant concentration in the anode region (101) which has a profile along the vertical direction (Z) according to which: - the first maximum (31) is present in the contact zone (1011) of the anode region (101); - the second maximum (32) is present in the field stop zone (1012) of the anode region (101); and - the dopant concentration decreases continuously from the first maximum (31) to the local minimum (33) and increases continuously from the local minimum (33) to the second maximum (32), the second maximum (32) being in the range from 70% to 130% of the first maximum (31). [19] The method of claim 18, wherein the electrically activated dopant concentration present at the second maximum (32) is higher than the electrically activated dopant concentration present at the first maximum (31). [20] A method according to claim 18 or 19, wherein: - providing (22) the electrically activated dopant concentration in the anode region (101) comprises performing a diffusion processing step to provide a base dopant concentration with the anode region (101). [21] A method according to claim 18, 19 or 21, wherein: - providing (22) the electrically activated dopant concentration in the anode region (101) comprises performing a first implantation processing step with a first implantation energy to generate the second maximum (32) and optionally performing a second implantation processing step with a second implantation energy to generate the first maximum (31); and / or wherein - providing (22) the electrically activated dopant concentration in the anode region (101) comprises performing a high-temperature annealing processing step to completely heal defects caused by the first implantation processing step or by the first and second implantation processing steps, thereby providing the electrically activated dopant concentration in the contact zone (1011) and the field stop zone (1012).

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