WO2010012257A1

WO2010012257A1 - Method for producing optoelectronic components and optoelectronic component

Info

Publication number: WO2010012257A1
Application number: PCT/DE2009/000941
Authority: WO
Inventors: Magnus Ahlstedt
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2008-07-31
Filing date: 2009-07-02
Publication date: 2010-02-04
Also published as: DE102008035901A1

Abstract

The invention relates to a method for the wafer-based production of a plurality of optoelectronic components (40, 100), which each include at least one semiconductor body (30) and a component housing, wherein a plurality of optoelectronic semiconductor bodies are provided, each having a first electrical contact (31) and a second electrical contact (32) and a substrate wafer (10, 100) with a first primary surface (120) and a second primary surface (120').

Description

description

Process for the production of optoelectronic components and optoelectronic component

The present invention relates to a method for the wafer-based production of a plurality of optoelectronic components and to an optoelectronic component.

Due to their high efficiency, their long service life and their robustness, optoelectronic components are increasingly replacing classical incandescent and discharge lamps in numerous fields of application. Surface-mountable designs play an important role here. They can be easily integrated into a wide variety of applications.

A recent technology for producing light surface mount LEDs is described in T. Murphy and J. Kuhmann, "Silicon wafer packaging for HB-LEDs", Technology White Paper, Hymite GmbH, September 2007.

So-called High Brightness LEDs require a housing structure that ensures good heat dissipation from the LED chip. In addition, other optical components, such as lenses, in a simple manner be integrated into such a housing structure.

An object of the present invention is to specify a method for producing an optoelectronic component which is wafer-based and comprises a few, as simple as possible process steps. Furthermore, a should Optoelectronic device can be provided, which is produced in a simple manner wafer-based. A method according to the invention may comprise the following steps:

Providing a substrate wafer having a first and one of the first opposing second major surfaces, applying an apertured mask layer to the first major surface, - forming trenches in the substrate in the region of the mask openings, removing the mask layer,

Forming a passivation layer lining the trenches, at least partially filling the trenches with metallic material,

Removing substrate material from the second major surface such that the metallic material is exposed on the side of the substrate wafer remote from the first major surface and thereby forming metallic feedthroughs through the substrate wafer, depositing an optoelectronic semiconductor body onto one of the metal feedthroughs, and electrically connecting of electrical contacts of the semiconductor body with metallic passage of the substrate wafer.

The formation of a lens enclosing the semiconductor body can take place, for example, by means of a transfer molding process or another casting, spraying or pressing technique. It is also possible that the lens is applied by dispensing. Furthermore, a method according to the invention may also comprise the following steps:

Providing a plurality of optoelectronic semiconductor bodies, each having a first electrical contact and a second electrical contact, providing a substrate wafer having a first major surface and a second major surface, forming at least two spaced depressions in the substrate wafer from the first major surface,

Introducing electrically conductive material into the depressions, thinning the substrate wafer such that the electrically conductive material in the region of the depressions forms electrically conductive passages through the substrate,

Applying the optoelectronic semiconductor body to the substrate wafer, - Forming electrically conductive connections between the electrical contacts of the semiconductor body and the respective associated feedthroughs, applying a plurality of encapsulating each at least one semiconductor body encapsulations on the substrate wafer, and

Dicing the substrate wafer between the encapsulations, such that separate optoelectronic components are formed.

When dividing the substrate wafer, it is also possible that is separated by the Verkapseiungen. The finished components then have on the side surfaces of the Encapsulation singling traces such as sawing on.

The application of the optoelectronic semiconductor body to the substrate wafer preferably takes place after the thinning of the substrate wafer.

The steps can be executed in a different order from the given order. However, the order given is preferred. In particular, the application of the optoelectronic semiconductor body to the substrate wafer preferably takes place after the thinning of the substrate wafer.

Metallic feedthroughs are formed in a substrate wafer, which are exposed both on its front side, that is to say its first main surface, and on its rear side, that is to say its second main surface. For structuring the trenches, a wet-chemical etching method or a dry etching method or a

Combination of such methods can be used. In this way, bushings with a large cross-sectional area can be produced, which enable good heat dissipation from the semiconductor body out of the component housing during operation of the optoelectronic component.

In an advantageous embodiment, the substrate wafer consists of an electrically conductive material, preferably of silicon or of a silicon-based material, and the inner surfaces of the

Wells provided before introducing the electrically conductive material with an electrically insulating layer. The encapsulation is preferably applied to the substrate wafer by means of a transfer molding process and preferably consists of a silicone material. The encapsulation can be technically very easily formed as a lens in this way.

The method allows the production of a flat design with a very stable connection between chip carrier and lens. A silicon substrate provides a very good surface for subsequent application of a silicone lens by transfer molding. There are only a few process steps required, which enables cost-effective production.

The recesses are advantageously produced by applying a mask to the first main surface of the substrate wafer and then etching the substrate material.

In an advantageous embodiment, the inner surfaces of the recesses are first provided with a metal layer and subsequently the recesses are at least partially filled with metallic material, for example by means of chemical or physical vapor deposition (CVD, PVD, PECVD).

In an advantageous embodiment, the filling of the recesses with metallic material takes place by means of screen printing of a metal paste and subsequent sintering of the metal paste. Especially with bushings with a larger diameter, the structure resolution of a screen printing process is sufficient. This embodiment has a low complexity in the process management. It requires no subsequent, for example, lithographic structuring of a metal layer on the substrate, so that in this way a simple and inexpensive production of the optoelectronic component is possible.

In another advantageous embodiment, metallic material is introduced into the recesses by means of a galvanic deposition method. The metallic material is, for example, deposited by means of a lithographically produced mask only in the wells.

In an advantageous variant, the metallic

Material on the side of the wells conform, that is deposited over the entire surface of the substrate wafer and subsequently removed outside the wells again from the substrate wafer. The latter is again accomplished, for example, by means of a lithographically produced mask and an etching process or by means of a chemical-mechanical polishing step.

When using a silicon substrate wafer, the mask is preferably formed by forming a mask layer on the substrate

Substrate wafer and subsequent lithographic patterning of the mask layer, such that at the locations where the recesses are provided, in the mask layer windows are formed, made. A mask layer made of silicon oxide can, for example, by means of thermal oxidation of the surface of the

Silicon substrate wafer or by CVD (Chemical Vapor Deposition) are formed. After the lithographic patterning of the mask layer, the depressions are subsequently inserted into the windows of the mask

Etched silicon substrate wafer, for example by means of KOH or a similar etchant or by means of a dry etching. Likewise, it is possible the wells in the silicon substrate wafer by means of a laser beam. Subsequently, the inner surfaces of the recesses are provided with an electrically insulating layer, for example by means of thermal or CVD passivation, followed by applying a seed layer for the metallic material for filling the recesses. An additional mask layer is applied to the seed layer and subsequently lithographically structured such that windows are located above the depressions through which the metallic material for filling the depressions is then introduced. In an alternative method, a metal paste is screen printed into the recesses and subsequently sintered before being plated with a metal layer for reinforcement.

Photolithography is a standard technique of semiconductor manufacturing and advantageously allows a high yield in already established process control.

For example, metals are deposited on the surface of a semiconductor wafer with high efficiency by a sputtering method. The resulting conformal coverage of the semiconductor wafer may be patterned by means of suitable resist masks to remove the metal (s) outside the pits. The resist is, for example, a resist or a photoresist. Since the pattern of the pits is complementary to that of the mask for the pits, preferably the same photomask can be used, resulting in a reduction of the production cost.

Presently suitable metals are, for example, gold, copper, palladium or any other combination of galvanic or otherwise depositable metals with sufficiently high thermal and / or electrical conductivity.

The exposing of the bushings on the second main surface, that is to say on the rear side of the substrate wafer, takes place in an advantageous embodiment of the method by means of a chemical-mechanical polishing method.

Subsequently, optoelectronic semiconductor bodies are applied to the substrate wafer, preferably each connected to one of the electrical feedthroughs, and the electrical contacts of the semiconductor body, each with an electrical feedthrough, before the encapsulations are then applied to the semiconductor body and finally the substrate wafer is severed between the encapsulations.

In a particularly advantageous embodiment of the method, a combination of a silicon substrate with a silicone lens is used as the encapsulation for the semiconductor body. Silicon and silicone adhere well to each other and therefore form an interface with high density.

An optoelectronic component according to the invention comprises a chip carrier substrate having a first main area, wherein at least two electrically separated feedthroughs are provided in the chip carrier substrate at least two electrically separated. An optoelectronic semiconductor body with at least two electrical contacts is applied to the chip carrier substrate and the electrical contacts are in each case electrically connected to one of the feedthroughs. The chip carrier substrate is finally with a - S -

Semiconductor body surrounding encapsulation, which is preferably formed as a lens provided.

Preferably, the optoelectronic component can be produced by a method described here. That is, the features disclosed for the method are disclosed for the device and vice versa.

In an advantageous embodiment, one of the electrical contacts overlaps with one of the bushings at least partially, preferably completely. As a result, good heat dissipation from the semiconductor chip to the rear side of the component is ensured in the operation of the component via this implementation.

The chip carrier substrate is preferably made of silicon or of a silicon-based material, which allows a cost-effective wafer-based production of optoelectronic components according to the invention.

Further advantages, advantageous embodiments and developments of the invention will become apparent from the embodiments described below in conjunction with FIGS. 1 to 2E. Here are function or effect same elements, areas and

Structures provided with the same reference numerals. Insofar as elements, regions or structures correspond in their function, their description is not repeated for each of the exemplary embodiments. Show it :

Figure 1 shows an embodiment of an optoelectronic

Halbleitererbauelernents in a schematic sectional view, and

FIGS. 2A to 2E show an exemplary embodiment of a method for producing an optoelectronic component in schematic sectional views.

The optoelectronic component 5 according to FIG. 1 comprises a chip carrier substrate 100, which preferably consists essentially of silicon or of a silicon-based material. Such substrates are collectively referred to herein as silicon substrates.

However, other materials such as gallium arsenide or germanium are not excluded.

The chip carrier substrate 100 has a first main surface 120 and a second main surface 120 'opposite thereto. At least two metal feedthroughs 24, 25 are formed in the chip carrier substrate 100. The metallic feedthroughs 24, 25 are electrically insulated from the adjacent material of the chip carrier substrate 100 by an electrically insulating layer 20 between substrate material and the electrical feedthroughs 24, 25, for example in the form of a passivation layer on the substrate material.

An optoelectronic semiconductor body 30 with two electrical contacts 31, 32 on opposite sides of the semiconductor body 30, for example an LED (Light Emitting diode) chip is applied to one of the two bushings 24 with one of its electrical contacts 31, for example by means of a conductive adhesive. The other electrical contact 32 is electrically connected by means of a bonding wire 33 as an electrically conductive connection with the other of the two bushings 25. The metallic leadthrough 24 may, for example, cover the back side of the LED chip, as shown in FIG. But it is also conceivable that the implementation 24 is smaller than the back of the LED chip is formed.

On the first main surface 120 of the chip carrier substrate 100, a silicone lens 40 is pressed onto the optoelectronic semiconductor body 30, which encloses the semiconductor body 30 including the bonding wire 33.

In the case of the above-described optoelectronic component 5, one of the two feedthroughs 24 is provided as a thermal connection for the optoelectronic semiconductor body 30, so that heat generated during operation in the semiconductor body from the interior of the component housing formed from the encapsulation 40 and the chip carrier substrate 100 via this feedthrough 24 can be directed to the outside.

With reference to FIGS. 2A to 2E, embodiments of a method for wafer-based production of a plurality of optoelectronic components 5 according to FIG. 1 are described below.

FIG. 2A shows the starting point of the method. There is a substrate wafer 10, for example a silicon wafer, with a first main surface 12 and one of these opposite second main surface 12 'provided. First and second main surfaces are referred to below as front side 12 and back side 12 'of substrate wafer 10, respectively.

On the front side 12 of the substrate wafer 10, a mask 14 is produced. As a starting point, for example, a silicon dioxide layer produced on the front side 12 may be used, for example as a thermal oxide or via a vapor phase deposition method on the first

Main surface 12 is formed. For structuring the mask

14, for example, a lithographic process is used in which a silicon dioxide layer is provided with windows 15 by means of a photomask and spin-on resist.

Subsequently, as also illustrated in FIG. 2A, in the substrate wafer 10 in the region of the windows

15 formed from the front side a plurality of spaced recesses 16 in the form of trenches. For this purpose, for example, an anisotropic etching process can be used, such as, for example, reactive ion etching (dry etching) or wet chemical etching with potassium hydroxide (KOH). Other etching methods are not excluded.

After etching the trenches 16, the mask 14 is removed from the substrate wafer 10.

On the front side 12, including the trenches 16 of the substrate wafer 10, a passivation layer 20 is then formed, which also lines the trenches 16 (see FIG. 2C). The passivation layer 20 may be made of, for example, silicon dioxide, either by thermal oxidation of the substrate wafer material or by means of deposition from the gas phase is formed.

In a first variant of the method, the trenches 16 are filled by conformal deposition of a metal layer, that is to say surface-wide deposition of a metal layer, and the metal layer outside the trenches 16 is removed again. For this purpose, for example by means of a sputtering method, a metal layer is applied to the front side 12, including inner surfaces of the trenches 16 of the substrate wafer 10, whose thickness corresponds, for example, to the depth of the trenches 16. The metal applied next to the trenches 16 on the substrate wafer 10 is subsequently removed, for example, by means of a further lithographic process section (cf. FIG. 2C).

The removal of the metal layer outside of the trenches 16 can also take place by means of chemical-mechanical polishing, in which the metal layer is removed to the front side of the substrate wafer.

Alternatively, for example, first a so-called metallic seed layer 22 is applied to the passivation layer 20, this is provided outside the trenches by means of a mask 14 'and then the trenches 16 with metallic

Material 23 filled before then the mask 14 'including metallic seed layer 22 and passivation layer 20 next to the filled trenches 16 is removed again (see Figure 2B).

The removal of the metallic seed layer 22 and the passivation layer 20 outside the trenches 16 is accomplished, for example, by means of chemical mechanical polishing performed in which the layers are removed to the front side 12 of the substrate wafer 10.

In a further variant of the method, the passages 24 are formed by screen printing of a metal paste and subsequent sintering of the metal paste. In order to achieve a good coverage, it is conceivable, after application of the passivation layer in the trenches 16, first to deposit a so-called metallic seed layer 22 ("seed layer").

Suitable metals for the bushings are, for example, gold, copper and palladium and any other combination of galvanically or otherwise depositable metals with a sufficiently high thermal and / or electrical

Conductivity. Other metals or alloys of metals are not excluded.

In a further step, the passages 24, 25 are now exposed at the bottom of the trenches 16, that is to say from the rear side 12 'of the substrate wafer 10 (see FIG. 2D). This is done, for example, by means of a chemical-mechanical polishing step.

An optoelectronic semiconductor body 30 is subsequently applied to a feedthrough 24 of a pair of feedthroughs 24, 25 of an optoelectronic component, such that one of its electrical contacts rests on the leadthrough 24 and is electrically and thermally conductively connected thereto, for example by means of a conductive adhesive. A second electrical contact of the semiconductor body 30 then becomes by means of a bonding wire 33 with the other passage 25 is electrically connected, see Figure 2E.

Subsequently, a plurality of lenses 40, for example made of silicone material, which in each case surrounds at least one of the optoelectronic semiconductor bodies 30 including the bonding wire 32, are applied to the substrate wafer 10. This is done for example by means of a transfer molding process.

For separating the substrate wafer with the semiconductor bodies and encapsulations applied thereto into optoelectronic components which are separate from one another, the substrate wafer is severed between the encapsulations, for example by means of sawing.

In a method according to the invention, electrical and / or thermal feedthroughs are formed in a substrate wafer, which are exposed on both sides of the substrate wafer. For the production of the passages depressions are formed in the substrate wafer, into which subsequently electrically and / or thermally conductive material is filled. The depressions are produced, for example, by means of a wet and / or dry chemical etching process. Also conceivable is the use of a mechanical method, such as milling. Furthermore, it is possible to form the recesses in the substrate wafer by means of a laser beam. A combination of the above-mentioned methods is also conceivable. Thus, for example, by means of a laser beam, a depression can be formed, which is subsequently widened with an etching process. With the method, bushings with a sufficiently large cross-sectional area can be realized in a technically simple manner for good heat dissipation from the semiconductor body.

Such a method advantageously allows the production of very flat designs for optoelectronic components, in particular LEDs.

This patent application claims the priority of German Patent Application 102008035901.7, the disclosure of which is hereby incorporated by reference.

The invention is not limited by the description with reference to the embodiments. Rather, the includes

Invention, each novel feature and any combination of features, which includes in particular any combination of features in the claims, even if this feature or this combination is not even explicitly stated in the claims or exemplary embodiments.

Claims

claims

1. A method for wafer-based production of a plurality of optoelectronic components (5) each having at least one semiconductor body (30) and a

Component housing (40, 100) with the following

Steps:

Providing a plurality of optoelectronic semiconductor bodies (30) each having a first electrical contact (31) and a second electrical contact (32),

Providing a substrate wafer (10) having a first major surface (12) and a second major surface (12 '), forming at least two spaced recesses (16) in the substrate wafer (10) from the first major surface (12);

Introducing electrically conductive material (23) into the depressions (16),

Thinning the substrate wafer (10) such that the electrically conductive material (23) is in the region of

Depressions (16) forms electrically conductive feedthroughs (24, 25) through the substrate (10), applying the optoelectronic semiconductor bodies (30) to the substrate wafer (10) after thinning the substrate wafer (10),

Forming of electrically conductive connections between the electrical contacts (31, 32) of the semiconductor body (30) and each associated bushings (24, 25), - applying a plurality of at least one semiconductor body (30) enveloping encapsulants (40) on the substrate wafer (10), and Dividing the substrate wafer (10) between the encapsulations (40) such that separate optoelectronic components (5) are formed.

2. The method of claim 1, wherein the substrate wafer (10) consists of an electrically conductive material, and the inner surfaces of the recesses (16) before introducing the electrically conductive material (23) with an electrically insulating layer (20) are provided.

3. The method of claim 2, wherein the substrate wafer (10) consists of silicon or of a silicon-based material.

4. The method according to any one of claims 1 to 3, wherein the Verkapseiungen (40) are produced by means of a transfer molding process.

5. The method according to any one of claims 1 to 4, wherein the encapsulants (40) are formed as lenses.

6. The method according to any one of claims 1 to 5, wherein the encapsulants (40) are made of a silicone material.

7. The method according to any one of claims 1 to 6, wherein the recesses (16) by means of applying a mask (14) on the first main surface (12) of the Substrate wafers (10) and subsequent etching of the substrate material can be produced.

8. The method according to any one of claims 1 to 7, wherein in the introduction of electrically conductive

Material (23) in the recesses (16), the inner surfaces of the recesses (16) are first provided with a metal layer (22) and subsequently the recesses (16) are at least partially filled with metallic material (23).

9. The method according to any one of claims 1 to 8, wherein the introduction of electrically conductive material (23) in the recesses (16) they are at least partially filled with screen paste by metal paste and subsequently the metal paste is sintered.

10. The method according to any one of claims 1 to 8, wherein the introduction of electrically conductive material (23) in the wells, these are at least partially filled with metallic material (23) by means of a galvanic deposition.

11. An optoelectronic component, comprising a chip carrier substrate (100) having a first main surface

(120), wherein in the chip carrier substrate (100) at least two electrically isolated from each other, electrically conductive bushings (24, 25) are provided, an optoelectronic semiconductor body (30) with at least two electrical contacts (31, 32) applied to the chip carrier substrate (100) is, the electrical contacts (31, 32) are each electrically connected to one of the bushings (24, 25) and the chip carrier substrate (100) is provided with an encapsulation (40) surrounding the semiconductor body (30).

12. The optoelectronic component according to claim 11, wherein one of the electrical contacts (31) overlaps at least partially with one of the bushings.

13. The optoelectronic component according to any one of claims 11 or 12, wherein the chip carrier substrate (100) consists of silicon or of a silicon-based material.

14. Optoelectronic component according to one of claims 11 to 13, wherein the encapsulation (40) is formed as a lens,

15. Optoelectronic component according to one of claims 11 to 14, wherein at least one of the bushings (24) as

Wärmeleitanschluss is provided for dissipating the thermal energy from the semiconductor body (30).