US-12617046-B2 - Method for attaching a first connection partner to a second connection partner

US12617046B2US 12617046 B2US12617046 B2US 12617046B2US-12617046-B2

Abstract

A method includes forming a first tacking layer on a first connection partner, arranging a first layer on the first tacking layer, forming a second tacking layer on the first layer, arranging a second connection partner on the second tacking layer, heating the tacking layers and first layer, and pressing the first connection partner towards the second connection partner, with the first layer arranged between the connection partners, such that a permanent mechanical connection is formed between the connection partners. Either the tacking layers each include a second material evenly distributed within a first material, the second material being configured to act as or to release a reducing agent, or the tacking layers each include a mixture of at least a third material and a fourth material, the materials in the mixture chemically reacting with each other under the influence of heat such that a reducing agent is formed.

Inventors

Alexander Heinrich
Andreas Waterloo

Assignees

INFINEON TECHNOLOGIES AG

Dates

Publication Date: 20260505
Application Date: 20220321
Priority Date: 20210325

Claims (17)

1 . A method, comprising: arranging a first connection partner on a second connection partner, with a first layer arranged between the first connection partner and the second connection partner; forming at least one of a first tacking layer between the second connection partner and the first layer and a second tacking layer between the first layer and the first connection partner; and heating the first layer and the at least one of the first tacking layer and the second tacking layer, and pressing the first connection partner towards the second connection partner such that a permanent mechanical connection is formed between the first connection partner and the second connection partner, wherein each of the at least one of the first tacking layer and the second tacking layer comprises a first material and a second material evenly distributed within the first material, the second material being configured to act as or to release a reducing agent, wherein the first material completely evaporates during the heating the first layer and the at least one of the first tacking layer and the second tacking layer, and wherein the second material remains after evaporation of the first material.
2 . The method of claim 1 , wherein the reducing agent comprises a carboxylic acid.
3 . The method of claim 1 , wherein the second material is evenly distributed within the first material, and wherein the first material is a volatile and inert material that evaporates under the influence of heat without residues.
4 . The method of claim 1 , wherein the second material is evenly distributed within the first material, and wherein the first material comprises carbon, oxygen, fluorine, nitrogen and hydrogen.
5 . The method of claim 4 , wherein the first material comprises one of Perfluorotributylamine, Perfluorotripentylamine, and Perfluorpolyether.
6 . The method of claim 1 , wherein the second material is evenly distributed within the first material, and wherein the reducing agent comprises formic acid.
7 . The method of claim 1 , wherein the heating of the first layer and the at least one of the first tacking layer and the second tacking layer is performed in a process chamber, and wherein an atmosphere inside the process chamber comprises essentially an inert gas or a vacuum is formed inside the process chamber.
8 . The method of claim 1 , wherein the first layer comprises a metal.
9 . The method of claim 1 , wherein the first layer has a first thickness in a vertical direction of 50 μm or less, wherein the vertical direction is a direction perpendicular to a main surface of the first layer, and wherein the main surface is a surface on which the at least one of the first tacking layer and the second tacking layer is formed.
10 . The method of claim 1 , wherein a top surface of the second connection partner on which the first tacking layer is formed comprises a metal, and wherein when heating the first tacking layer, the reducing agent that is present in or is formed from the first tacking layer activates the top surface of the second connection partner, and wherein activating the top surface of the second connection partner comprises reducing a metal oxide layer formed on the top surface of the second connection partner to pure metal.
11 . The method of claim 1 , wherein a bottom surface of the first connection partner adjacent to the second tacking layer comprises a metal, and wherein when heating the second tacking layer, the reducing agent that is present in or is formed from the second tacking layer activates the bottom surface of the first connection partner, and wherein activating the bottom surface of the first connection partner comprises reducing a metal oxide layer formed on the bottom surface of the first connection partner to pure metal.
12 . An arrangement, comprising: a first connection partner arranged on a second connection partner; a first layer arranged between the first connection partner and the second connection partner; and at least one of a first tacking layer arranged between the second connection partner and the first layer and a second tacking layer arranged between the first layer and the first connection partner, wherein each of the at least one of the first tacking layer and the second tacking layer comprises a first material and a second material evenly distributed within the first material, the first material being configured to completely evaporate upon an application of sufficient heat, the second material being configured to remain after evaporation of the first material and to act as or to release a reducing agent.
13 . The arrangement of claim 12 , wherein: either the first connection partner is a semiconductor body and the second connection partner is a substrate; or the first connection partner is an electrical connection and the second connection partner is a semiconductor body.
14 . A method, comprising: arranging a first connection partner on a second connection partner, with a first layer arranged between the first connection partner and the second connection partner; forming a first tacking layer between the second connection partner and the first layer and a second tacking layer between the first layer and the first connection partner; and heating the first layer, the first tacking layer, and the second tacking layer, and pressing the first connection partner towards the second connection partner such that a permanent mechanical connection is formed between the first connection partner and the second connection partner, wherein each of the first tacking layer and the second tacking layer comprises a first material and a second material evenly distributed within the first material, the second material being configured to act as or to release a reducing agent, wherein the first material completely evaporates during the heating the first layer and the at least one of the first tacking layer and the second tacking layer, and wherein the second material remains after evaporation of the first material.
15 . The method of claim 14 , wherein the second material is evenly distributed within the first material, and wherein the first material is a volatile and inert material that evaporates under the influence of heat without residues.
16 . The method of claim 14 , wherein the second material is evenly distributed within the first material, and wherein the first material comprises carbon, oxygen, fluorine, nitrogen and hydrogen.
17 . The method of claim 14 , wherein the second material is evenly distributed within the first material, and wherein the reducing agent comprises formic acid.

Description

TECHNICAL FIELD The instant disclosure relates to a method for attaching a first connection partner to a second connection partner. BACKGROUND Power semiconductor module arrangements often include at least one semiconductor substrate arranged in a housing. A semiconductor arrangement including a plurality of controllable semiconductor elements (e.g., two IGBTs in a half-bridge configuration) is arranged on each of the at least one substrate. Each substrate usually comprises a substrate layer (e.g., a ceramic layer), a first metallization layer deposited on a first side of the substrate layer and a second metallization layer deposited on a second side of the substrate layer. The controllable semiconductor elements are mounted, for example, on the first metallization layer. Before permanently attaching the semiconductor elements to the substrate, the substrate often needs to be transported from one manufacturing facility to another. For transport between different manufacturing facilities, the semiconductor elements can be temporarily attached to the substrate. A solder preform can be arranged between the substrate and the semiconductor element, the solder preform being attached to the substrate by means of a layer formed by a so-called tacking agent, and the semiconductor device being attached to the solder preform by means of a further layer of tacking agent. When forming the permanent connection between the semiconductor device and the substrate by means of the solder preform, the layers of tacking agent have to be removed without any residues and, at the same time, a surface of the substrate needs to be activated. That is, a metal oxide that might have formed on the surface of the substrate needs to be reduced to pure metal. There is a need for a method for attaching a first connection partner to a second connection partner. SUMMARY A method includes forming a first tacking layer on a second connection partner, arranging a first layer on the first tacking layer, forming a second tacking layer on the first layer, arranging a first connection partner on the second tacking layer, and heating the first tacking layer, the second tacking layer, and the first layer, and pressing the first connection partner towards the second connection partner, with the first layer arranged between the first connection partner and the second connection partner, thereby forming a permanent mechanical connection between the first connection partner and the second connection partner, wherein either the first and second tacking layers each include a first material and a second material evenly distributed within the first material, wherein the second material is configured to act as or to release a reducing agent, or the first and second tacking layers each include a mixture of at least a third material and a fourth material, wherein the materials comprised in the mixture chemically react with each other under the influence of heat, thereby forming a reducing agent. An arrangement includes a first tacking layer arranged on a second connection partner, a first layer arranged on the first tacking layer, a second tacking layer arranged on the first layer, and a first connection partner arranged on the second tacking layer, wherein either the first and second tacking layers each include a first material and a second material evenly distributed within the first material, wherein the second material is configured to act as or to release a reducing agent, or the first and second tacking layers each include a mixture of at least a third material and a fourth material, wherein the materials comprised in the mixture chemically react with each other under the influence of heat, thereby forming a reducing agent. The invention may be better understood with reference to the following drawings and the description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a power semiconductor module arrangement. FIGS. 2A to 2C schematically illustrate a method for attaching a semiconductor device to a substrate according to one example. FIG. 3 schematically illustrates an arrangement in which a semiconductor body is temporarily attached to a substrate. FIG. 4 schematically illustrates a chemical reaction cascade for forming oxalic acid. FIGS. 5A and 5B schematically illustrate an arrangement in which a semiconductor body is permanently (FIG. 5A) or temporarily (FIG. 5B) attached to a substrate, and in which an electrical connection is permanently (FIG. 5A) or temporarily (FIG. 5B) attached to a semiconductor body. DETAILED DESCRIPTION In the following detailed description, reference is made to the accompanying drawings. The drawings show specific examples in which the invention may be p