EP2396814A2

EP2396814A2 - Method for producing a connection between a semiconductor component and semiconductor module resistant to high temperatures and temperature changes by means of a temperature impinging process

Info

Publication number: EP2396814A2
Application number: EP10710533A
Authority: EP
Inventors: Mathias Kock; Ronald Eisele
Original assignee: Danfoss Silicon Power GmbH
Current assignee: Danfoss Silicon Power GmbH
Priority date: 2009-02-13
Filing date: 2010-02-04
Publication date: 2011-12-21
Also published as: CN102396057B; WO2010091660A2; US9287232B2; JP5731990B2; US20120037688A1; WO2010091660A3; DE102009008926B4; CN102396057A; DE102009008926A1; JP2012517704A

Abstract

The invention relates to a method for producing a connection between a semiconductor component and semiconductor module resistant to high temperatures and temperature changes by means of a temperature impinging process, wherein a metal powder suspension is applied to the areas of the semiconductor module to be connected later; the suspension layer is dried, outgassing the volatile components and generating a porous layer; the porous layer is pre-sealed without complete sintering taking place throughout the suspension layer; and, in order to obtain a solid electrically and thermally conductive connection of a semiconductor module to a connection partner from the group of: substrate, further semiconductor or interconnect device, the connection is a sintered connection generated without compression by increasing the temperature and made of a dried metal powder suspension that has undergone a first transport-safe contact with the connection partner in a pre-compression step and has been solidified at zero pressure using temperature sintering.

Description

Method for creating a high temperature and temperature change resistant

Connecting a module semiconductor and a semiconductor device with a temperature-applying method

The invention relates to a method for creating a high-temperature and temperature-resistant connection of a module semiconductor and a semiconductor device with a temperature-applying method.

State of the art

The increasing demand for power electronics, in particular for power tools (hybrid vehicles), considerably increases the numbers of units in which power semiconductor assemblies are manufactured. In order to keep pace with the costs that naturally have to be minimized in motor vehicle production, the manufacturing processes are constantly being optimized.

A complex step in the production of sintered compounds, as described for example in DE 10 2006 033 073 B3 of the Applicant, are in the actual sintering (the so-called final sintering) required pressures of more than 30 MPa, by a special apparatus have to be applied for a few seconds to a few minutes.

On the other hand, it is already known from this cited document that a saw-proof dried metal powder suspension is pre-compacted after a drying and heating step after the application of even low pressure such that it is "capable of being sawed". Furthermore, it is known from known soldering methods that a suitable temperature control of the workpiece allows a melting on the workpiece arranged soldering material for producing an intimate solder joint.

The invention is based on the finding that by selecting a suitable metal powder suspension by activating this, either by local, low pressure of for example 5 MPa or by heating to z. B. 25O ⁰ C, the sintering process can be initiated so far that a transport-resistant fixation for processing by further manufacturing steps takes place.

In this case, an electrical component with metallic contact surfaces with either a silver or a gold surface by materially joined to a substrate material in several stages of production, without a critical sintering pressure is applied.

This makes it possible to carry out the method according to the invention without an expensive press station, so that the clock rates can be increased considerably and yet modules with sintered connection can be produced.

In this case, circuit substrate can be used as a substrate material, such as. As organic printed circuit boards (PCB, ceramic circuit boards, DCB, metal core circuit boards, IMS or conductor leadframes, stamped grid, hybrid ceramic circuit carrier, etc.). The electrotechnical component can be an inexhaustible Halbeiterbauelement or a gemoldetes, d. H. be cased semiconductor device. Electrical contact terminals SMD-B auelemente or the like can also be connected to each other with the cohesive joining method according to the invention.

The difference to the so-called low-temperature sintering, in which by simultaneous quasi-isostatic pressing with pressures of 20 to 30 MPa and simultaneous heating of the joining partners to about 22O ⁰ C is a connection is that now with significantly lower pressures a connection tact-fast, ie when heated for a few seconds.

At the same time, the following disadvantages of the prior art are avoided: Due to the previous simultaneous application of high pressure and temperature increase, static and dynamic stresses in materials of the joining partners are induced, which, for example in the case of unhoused silicon semiconductor components and ceramic printed circuit boards, could lead to these very brittle materials cracking.

The natural brittleness of these materials was demanded by the typical processing methods. Initial microcracks were added to the silicon chips by sawing on the saw edges (so-called chipping). The ceramic circuit boards were already given a partial pre-damage by breaking, which was followed by laser scribing.

It was not until the subsequent high-pressure treatments that a disturbing crack growth up to the destruction of the component was observed in classical low-temperature sintering. For some non-planar devices, low-temperature sintering is directly destructive because of component brittleness and difficult three-dimensional shapes (eg, SMD resistors and SMD capacitors), and so sintering has not hitherto been open to these applications.

The procedure according to the invention now yields three advantages over the prior art:

• The placement and fixing of the electronic component is done by low forces that are just suitable to keep the component at the desired location on the circuit board.

• Fixing and sintering are separate processes. The fixing takes place predominantly by a clawing in the surface of the joining partners or the silver joining layers.

• The subsequent sintering is carried out without pressure in a heating furnace at temperatures between 170 ° C to 300 ° C, so it may be easily inserted in a transport line for components. • To promote sintering quality, the atmosphere for certain metal suspension layers can optionally be adjusted with an inert or reactive gas. Nitrogen is suitable as the inert gas, for example, and forming gas or inert gas saturated with formic acid can be used as the reactive gas.

One has to imagine the locking in the fixation like the interlocking of snow crystals when rolling snowman balls. Due to the rough surface and the possibility of compaction results in the claw, without the layer thickness decreases significantly.

Further advantages and features of the invention will become apparent from the following description of a preferred embodiment with reference to an accompanying drawing. Showing:

FIG. 1 shows a metallized device placed over a precoated and dried metal suspension layer. FIG.

Fig. 2, the elements of Fig. 1, which are fixed together by low pressure

3 shows the elements of FIG. 2 after an unpressurised temperature control step, which ensures preferably complete volume sintering, FIG.

4 shows a lower and further metallized component on a previously applied and dried metal suspension layer as in Fig. 1,

5, the elements of FIG. 4, which are fixed together by low pressure and an over - yet separately arranged - contact tab,

FIG. 6 shows the elements of FIG. 5, wherein the contact tab with the other elements is fixed by low pressure, and FIG. 7 shows the elements of FIG. 6 after a pressure-free tempering step, which ensures a preferably complete volume sintering of all fixed contact positions

Step 1:

A substrate material or a chip backside, or in a preferred embodiment on both surfaces to be joined, is applied in a uniform layer thickness by means of a layer containing silver particles, preferably with a stencil printer. This is done selectively at the points where the device is to be placed or, if applied to the chip, a full surface. Other application techniques, in particular spraying, are conceivable. On the other hand, diving or spin-on of a silver particle solution would cause problems with layer-wide variance.

Step 2:

After application, the layer is dried and freed from the volatile organic compounds. Temperatures of up to 150 ⁰ C support the process to ensure high clock rates. The dried layer produced thereby has a large porosity and a large roughness.

If this step were to be dispensed with and so-called "wet application" carried out, it would be feared that the still mobile silver particles would still move in the solvent suspension during outgassing and channels would form to discharge the solvent in the layer Thus, complete drying of the layer is an integral part of the process, whether or not the metal suspensions are provided with thermally activating constituents, but preferably such compositions are chosen which do not yet exist at a drying temperature of 150 ° C locally release additional exothermic energy, but do so only at the much higher temperature of for example 25O ⁰ C, because they are activated only by these high temperatures. In agreement with the selected composition of the metal powder suspension, the drying temperature can be chosen so high for accelerating the process that premature (nor) sintering is omitted.

Step 3:

The electrotechnical component is brought to a predetermined position by a component gripping and depositing device and unilateral or bilateral silver layers applied to the components are pressed together by the force applied during the application and clawed together. This is a short 0.1 to 3 second placement process, with the required force only enough to reshape the rough surface and claw each other. The bracket by Verkrallen does not have to meet the requirements for later use but only be so strong that during the process of locomotion in the manufacture of the components no longer slip.

As already illustrated by the example of snow, the two-dimensional clawing of the rough dried metal layer in a silver or gold surface provides for easy adhesion. Similarly, a snowball sticks to a cement wall, or even snow, when a snowball is formed.

If the adhesion is not sufficient at room temperature at this point, the adhesion can be improved again by increasing the temperature up to, for example, 150 ° C. In the example "snow" this would be equivalent to a wet snow.

Step 4: In a fourth step, the component thus fixed is finally subjected to a subsequent heat process without further pressure, wherein a diffusion of the silver atoms into the interface of the joining partner and vice versa takes place, so that the desired high temperature and temperature change resistant, for motor vehicle applications also stable connection over many years.

FIG. 1 shows a pre-metallized component which is precoated with an example of about 50 micrometers and at a temperature of about 50 micrometers. temperature of less than 140 ° C for a few minutes (preferably 1-3 minutes) dried metal suspension layer is placed. A suitable pre-compaction of the layer in order to store it better, and to avoid abrasion, may have already taken place on the layer before the component is fixed.

Furthermore, in a variant on one of the connection partners, a layer produced in the same or a similar way - even in order to use it as similar to a pre-metallization - may also have already been sintered. It is sufficient if a layer still consists only of dried, non-sintered paste / suspension.

Then the elements (see Fig. 2) are fixed together by low pressure. In this case, a pressure of 1-10 MPa, preferably 2-6 MPa, and herein more preferably for a second less than 5 MPa can be exercised.

Fig. 3 shows the elements of FIG _. 2 after a non-pressurized tempering, at paste-dependent temperatures of typically more than 230 ⁰ C, which ensures a preferably complete volume sintering. Reactive process gases can accelerate sintering.

Figs. 4 to 7 show, as representative of many possible elements, a contact tab is fixed by low pressure with the assembly in the same way.

hi very advantageous manner is fixed by low pressure on the contact strap this already transportable with the other elements, and finally with a dracklosen tempering, which ensures a preferred complete volume sintering of all fixed contact positions (eg, many contact tabs), the desired high-temperature and temperature change resistant, stable over many years compound obtained (Fig. 7).

The erfmdungsgemäße method for creating a high-temperature and tempe- raturwechselfesten connection of a module semiconductor and a semiconductor device with a temperaturbeaufschlagenden method in which a metal powder suspension is applied to the areas of the individual semiconductor devices to be joined later, the suspension layer with outgassing of the volatile constituents and dried to form a porous layer, then precompressed the porous layer, without a complete, the Sus- pensionsschicht penetrating sintering takes place, wherein to obtain a solid electrically and thermally well-conductive compound of a semiconductor device on a connection partner from the group: substrate, further semiconductor or circuit carrier, the compound is a sintered compound produced without pressing pressure by increasing the temperature, which consists of a dried metal powder suspension consists, in a Vorverdichtungsschritt with the connection partner has undergone a first transport-resistant contact with the connection partner, and was solidified under temperature Ausausung unpressurized in a preferred embodiment can be extended daurch that more than one side of a connection partner is provided with metal suspension order.

Further, to promote sintering quality, the atmosphere (in a sealed chamber) may be enriched with an inert or reactive gas during heating. The inert gas may preferably contain nitrogen as a main component. The reactive gas proposed is one with a predominant constituent of forming gas.

Claims

claims

Anspruch [en] 1. A method for providing a high-temperature and temperature-changeable connection of an assembly semiconductor and a semiconductor component with a temperature-influencing method, in which

a metal powder suspension is applied to the regions of the individual semiconductor components to be connected later,

the suspension layer is dried with outgassing of the volatiles and to form a porous layer,

the porous layer is precompressed without a complete, the suspension layer penetrating sintering takes place,

characterized in that

for obtaining a solid electrically and thermally well-conductive connection of a semiconductor component on a connection partner from the group: substrate, further semiconductor or circuit carrier, the compound is a sintered compound produced by pressing without increasing temperature by pressure increase, which ordered from a dried metal powder suspension, in a Vorverdichtungsschritt with the connection partner has undergone a first transport-resistant contact with the connection partner, and was solidified under pressure Ausausausung temperature.

2. The method according to claim 1, characterized in that more than one side of a connection partner are provided with metal suspension order.

3. The method according to claim 1 or 2, characterized in that to promote the sintering quality, the atmosphere is enriched with an inert or reactive gas.

4. The method according to any one of the preceding claims, characterized in that takes place for promoting the quality of sintering Temperaturaussinterung under nitrogen.

5. The method according to any one of the preceding claims, characterized in that takes place to promote the quality of sintering drying under Formiergas.