DE102019218819A1 - Micromechanical-optical component and method for manufacturing a micromechanical-optical component - Google Patents

Abstract

The invention relates to a micromechanical-optical component with a glass cover (6), a spacer (40) and a component substrate (2), - the spacer having a recess which forms a cavity (28) that is separated from the glass cover and the component substrate is limited, - wherein an optical semiconductor component (1) is arranged in the cavern, which is attached to the component substrate and is set up to send optical radiation through the glass cover, - wherein the spacer and the component substrate by means of a first material connection (5 ) are connected to one another, - the glass cover and the spacer being connected to one another by means of a second material connection (13), - A first absorption layer (12) being arranged on the first material connection and a second absorption layer (14) being arranged on the second material connection The invention also relates to a method of making a micro mechanical-optical component.

Description

State of the art

The invention relates to a micromechanical-optical component in the form of a micromechanically packaged optical semiconductor component and an associated manufacturing method.

Many optically active components have to be operated in a hermetic atmosphere. Some laser diodes, for example, have to be operated in an environment free of moisture and organic components in order not to significantly reduce their service life. Active micromirrors operated sometimes have to be operated at negative pressure in order to avoid attenuation by the surrounding gas. Or the optical components have to be protected from contamination or the accumulation of particles.

In order to achieve this, the optical components can be packaged individually in a housing which is provided with at least one optical window. Metal housings are often used for this purpose, which on the one hand have ceramic bushings in order to be able to lead electrical signals to the optical component and on the other hand have at least one glass window in order to be able to lead an optical signal in or out of the optical component. It is often important that the optical component usually has to be mounted very precisely relative to the housing and that the window must also be adjusted relatively precisely to the optical component.

The disadvantage of this concept is that known metal housings are mostly very large and expensive. Another disadvantage is that the adjustment accuracy in such systems is usually very imprecise.

Micromechanical acceleration sensors and yaw rate sensors and their production methods are also known. The sensors are manufactured at the wafer level, i.e. in large numbers on a silicon substrate (wafer) in parallel with one another, and also at the wafer level, usually via a bonding process in which a further wafer is applied to the wafer with the sensors in one Hermetically sealed cavern. The manufacturing process is relatively inexpensive, since the individual, per se expensive, work steps are carried out at the wafer level, i.e. simultaneously for an ensemble of many individual sensors. The commonly used bonding processes require a high bonding temperature, but at the same time enable a hermetic and very robust connection. It would be advantageous if optically active components could also be hermetically and robustly sealed at wafer level. A simple use of this process for optical components is not possible, however, since the optically active components normally cannot withstand the high bonding temperatures.

task

An arrangement and a manufacturing method are sought to hermetically and robustly pack optical components in a wafer assembly. The method should make it possible to hermetically protect the optical components and at the same time the thermal load on the optical components should be kept as low as possible during the manufacturing process.

Advantages of the invention

The invention relates to a micromechanical-optical component with a glass cover, a spacer and a component substrate, the spacer having a recess which forms a cavity which is delimited by the glass cover and the component substrate, an optical semiconductor component being arranged in the cavity, which is attached to the component substrate and is set up to send optical radiation through the glass cover, the spacer and the component substrate being connected to one another by means of a first material connection, the glass cover and the spacer being connected to one another by means of a second material connection, wherein a first absorption layer is arranged on the first material connection and a second absorption layer is arranged on the second material connection. The device has a simple structure.

The component substrate is advantageously a ceramic. The component can advantageously be contacted well and heat can be dissipated.

An advantageous embodiment of the micromechanical-optical component provides that the first material connection or also the second material connection is a seal glass bond. A hermetic cavern can advantageously be created in this way.

It is advantageous that the cavern is hermetically sealed. As a result, the optical semiconductor component is protected from dust, moisture and other environmental influences.

An advantageous embodiment of the micromechanical-optical component provides that the first absorption layer is a layer on the component substrate. The component substrate can advantageously be connected to the spacer with only a small amount of local heat input. See an advantageous embodiment of the micromechanical-optical component suggest that the second absorption layer is a layer on the glass lid. The glass cover can also advantageously be connected to the spacer with only a small amount of local heat input.

An advantageous embodiment of the micromechanical-optical component provides that the second absorption layer is a doped region of the spacer. In this way, the glass lid can advantageously be connected to the spacer with a transparent seal glass.

An advantageous embodiment of the micromechanical-optical component provides that at least one frame is arranged on the spacer, which frame surrounds the glass cover or also the component substrate. In this way, a particularly robust device can advantageously be created in which the glass cover or the component substrate in particular are protected, or the spacer can be made very thin, which reduces the overall height of the device.

The invention also relates to a method for producing a micromechanical-optical component.

In an advantageous embodiment of the method, optical elements, including an optical semiconductor component on a single component substrate, are first applied individually to a spacer wafer using a first through-light welding method. A first bond between the spacer wafer and the component substrate is thermally activated with an IR laser through the spacer wafer. A glass cover is then attached to the spacer wafer, again using a second through-light welding process. In this step, a bond between the glass cover and the spacer wafer is thermally activated with a laser through the glass cover. Finally, the micromechanical-optical components are separated.

By using the transmitted light welding process, which can also be used with very fast local pulses with the aid of a laser, very robust bond connections that require high temperatures for activation can be used on the one hand. On the other hand, the use of local pulses only heats the bond connection. Elements that are at a certain distance from the bond connection are not or almost not heated.

The transmitted light welding process is used twice from the same side. The bond connections can thus also be arranged directly one above the other. Very small components are possible.

The transmitted light welding is preferably carried out from above, which makes it possible to arrange the contact areas directly below the bond. Very small components are possible.
In alternative refinements of the method, however, the first and second transmitted light welding are also carried out from opposite sides.

Overall, it is a simple manufacturing process. Above all, the method is compatible with the optical semiconductor component and avoids damaging it in the manufacturing process of the device. Avoided risks include, for example, excessive exposure to temperature, pressure and aggressive media. The method according to the invention enables precise adjustment of the optical semiconductor component to the spacer or spacer wafer and thus in particular also to a mirror surface. It also allows an exact adjustment of an optical window, the glass cover to the spacer. After all, the package produced is very small.

Figure list

• The 1 a - e show, in various stages of the device, a method for producing a micromechanical-optical component according to the invention in a first exemplary embodiment.
• The 2 a and b show, in different stages of the device, a method for producing a micromechanical-optical component according to the invention in a second exemplary embodiment.
• The 3 a - d show, in various stages of the device, a method for producing a micromechanical-optical component according to the invention in a third exemplary embodiment.
• 4th shows schematically the method according to the invention for producing a micromechanical-optical component.

description

The 1 a - e show, in various stages of the device, a method for producing a micromechanical-optical component according to the invention in a first exemplary embodiment.

First is a spacer wafer 4th with a continuous recess 8th produced ( 1a) . For optical elements that emit or receive a signal that does not run perpendicular to the wafer plane, it is advantageous to provide a passive optical element such as a mirror in the spacer wafer to achieve a suitable beam path in a simple manner. For example, a defined inclined flank can be etched into a monocrystalline silicon wafer with a defined crystal orientation via KOH etching, which acts as a mirror flank 9 is usable.

The individual optical components, in particular an optical semiconductor component 1 , are now on a component substrate 2 brings up. It is advantageous to use a ceramic substrate because it is inexpensive and has good thermal conductivity. It is favorable to use a substrate with electrical through-contacts in order to generate the electrical accesses early and inexpensively. A substrate with prepared rear-side contacts is favorable 10 to use. Preferably, the components on the substrate can already be tested and sorted out depending on the measured value, so that only good components are further processed.

The individual optical components are now on the back of the spacer wafer 4th into the recess 8th brought in. The component substrate 2 , a single substrate, is adjusted in the recess and applied to the spacer wafer using a transmission bonding process. It is done with a short heat pulse, for example an IR laser beam 3rd a first material connection 5 , creates a hermetic connection between spacer wafer and component substrate ( 1b) .

A seal-glass process is preferably used, with the bonding frames being able to be applied to the spacer wafer in a particularly cost-effective manner by means of a screen printing process.

It is particularly favorable if a first absorption layer is provided on the component substrate at least in the area of the future bond connection 12th , in particular a metal-containing layer, is arranged in order to be able to achieve a targeted heating of the bond there.

The component substrate can be adjusted on the spacer wafer by adjusting a characteristic feature of the optical element to a characteristic feature of the mirror in the spacer wafer. It is particularly advantageous if a fine adjustment is made from the front. The mirror element can 9 and the optical element 1 in the continuous recess 8th can be observed at the same time. A particularly high level of adjustment accuracy can thus be achieved.

The new seal glass bond frame is preferably warmed up with a short laser pulse. The Laser-Plus is preferably used for less than 200 msec. The Laserplus can also be used as a multiple pulse. A laser with a wavelength of more than 600 nm is preferably used.

The laser pulse is preferably only applied locally in the area of the new seal glass bond frame. The laser pulse is preferably introduced from the front side, that is to say shines through the spacer wafer before it hits the area of the first material connection to be created 5 meets.

Individual glass lids are placed on the spacer wafer 6th bonded ( 1c ). A second material connection is thus created by means of a transmission bonding process 13th created. Again, a seal-glass-bond process is preferably used.

The seal glass bond frames are preferably warmed up with a short laser pulse. The Laser-Plus is preferably used for less than 200 msec. The Laserplus can also be used as a multiple pulse. A laser with a wavelength of more than 600 nm is preferably used.

The laser pulse 7th is preferably only applied locally in the area of the new seal glass bond frame. The laser pulse is preferably introduced from the front.

It is advantageous to apply the seal glass bond frame to the spacer wafer. Then preferably on the underside of the glass cover in areas of the bonding frame 13th a second absorption layer 14th be applied in order to be able to achieve a targeted heating of the bond connection there. This layer can advantageously also be used as a masking layer in other areas of the glass cover, for example in order to block undesired scattered radiation from the cavity.

In an optional further step, on the back of the individual substrate 2 Contact surfaces are generated or further processed ( 1d ). For example, it is advantageous to first provide the component substrates with flat contact surfaces and then in this step, that is, after bonding onto the spacer wafer in the wafer assembly, solder balls 15th to apply to the contact surfaces. With such a sequence, the solder balls cannot be damaged in the bonding process, easier handling in the bonding process is possible, and in the wafer assembly the balls can be applied cost-effectively to all contact surfaces at the same time.

In a final step, the components are separated by sawing the spacer wafer. From the spacer wafer 4th creates a spacer 40 . As a result, in a first embodiment, an inventive micromechanical optical component with a glass cover 6th , a spacer 40 and a component substrate 2 created ( 1e) . The spacer has a recess which forms a cavity 28 forms, which is delimited by the glass cover and the component substrate, In the cavity is an optical semiconductor component 1 arranged, which is attached to the component substrate and is set up along a beam path 50 to send optical radiation through the glass lid. For this purpose, the spacer has a beam-deflecting element in the form of a mirror flank 9 on. The spacer and the component substrate are connected by means of a first material connection 5 , bonded together with a seal glass bond.

The glass lid and the spacer by means of a second material connection 13th , also connected to each other with a Seal Glass Bond. At the first material connection, here between the seal glass and the component substrate, there is a first absorption layer 12th arranged in the form of a coating of the component substrate. At the second material connection, here between the seal glass and the glass lid, there is a second absorption layer 14th arranged in the form of a coating on a side of the glass cover facing the cavern. On a rear side of the component substrate 2 are rear contacts 10 with solder balls 15th arranged.

The 2 a and b show, in different stages of the device, a method for producing a micromechanical-optical component according to the invention in a second exemplary embodiment.

In an alternative embodiment of the method according to the invention, the individual component substrates are in a first step 2 with a first transmitted light welding process 3rd with light irradiation from the front of the spacer wafer 4th materially connected ( 2a) . In a further step, the glass lids are attached to the spacer wafer and with a second transmitted light welding process 7th materially connected from the back of the spacer wafer ( 2 B) .

The advantage of this arrangement is that the transmitted light welding process is always carried out by the spacer wafer and that this process can be utilized and controlled very well. The first material connection 5 and the second material connection 13th are arranged offset to this in such a way that a laser beam for the second transmission bonding 7th next to the component substrate 2 over and through the spacer wafer 4th can be passed through.

It is advantageous in this arrangement if a first absorption layer is used before the first bonding process 12th on the individual component substrate 2 , is arranged and the seal glass for the first material connection 5 with a screen printing process on the back of the spacer wafer 4th is applied.

It is favorable in this arrangement if a second absorption layer is used before the second bonding process 14th on the glass lid 6th is provided and the seal glass for the second material connection 13th with a screen printing process on the front of the spacer wafer 4th is applied.

In a final step (not shown) the components are separated by sawing the spacer wafer. As a result, in a second exemplary embodiment, a micromechanical-optical component according to the invention is created in which the first material connection 5 and the second material connection 13th are arranged side by side, seen in a phantom view perpendicular to a main plane of the device ( 2 B) .

The 3 a - d show, in various stages of the device, a method for producing a micromechanical-optical component according to the invention in a third exemplary embodiment.

In an alternative embodiment of the method according to the invention, doping is used as the second absorption layer 14th created. A spacer wafer 4th is provided for this purpose and a doping on its front side 18th brought in ( 3a) . This can be beneficial if, for example, you are standing on the glass lid 6th as a second material connection 13th provides a transparent seal glass bond frame and through the glass lid 6th through the second bonding process 7th undertakes. A local doping layer with preferably As, P, B, Sb or Al is favorable for this. The same procedure can also be applied to the first material connection 5 with the individual substrates 2 be applied. For this purpose, the spacer wafer would have to be doped accordingly on its rear side.

In an alternative embodiment of the method according to the invention, a frame is used for the glass cover 6th or the component substrate 2 created. To do this, an auxiliary wafer is first used 16 on one side or on both sides of the spacer wafer 4th applied and attached. Again, this can be done by a bonding process. The auxiliary wafer 16 has through holes for this purpose 17th that are larger than the passage cavity in the spacer wafer. The through holes in the auxiliary wafer can be used to adjust the glass cover in a favorable manner 6th or the individual substrates 2 to the spacer wafer 4th facilitate and secure them against slipping in the bonding process, or just allow pre-adjustment and inexpensive pre-assembly. 3b shows an example of a frame for the glass lid. In addition to the frame, which through the auxiliary wafer 16 with the hole 17th is formed, is the doped region 18th , which is the second absorption layer 14th forms. It is also favorable if the auxiliary wafer is chosen to be thicker than the glass cover or, when used on the rear side of the spacer, thicker than the individual substrates. With the auxiliary wafer, the individual elements can be very well protected during further processing and, at the same time, a new surface with a clearly defined height is created for further processing. Furthermore, the spacer wafer is also very well stabilized by the auxiliary wafer. In principle, this makes it possible to select the spacer wafer significantly thinner. If the auxiliary wafer is removed completely later, for example in the singulation process, it can be used to produce extremely thin individual components. 3c shows the following first transmission bonding 3rd , at the component substrate 2 and spacer wafers 4th be connected to each other. 3d shows the subsequent second transmission bonding 7th , at the spacer wafer 4th and glass lid 6th be connected to each other.

In a final step, the components are separated by sawing the spacer wafer and the auxiliary wafer. From the spacer wafer 4th creates a spacer 40 , and from the auxiliary wafer 16 creates a framework 160 . As a result, in a third exemplary embodiment, there is a micromechanical-optical component according to the invention with a frame 160 around the glass lid and with a second absorption layer 14th in the form of a doped area 18th of the spacer 40 created ( 3d ).

4th shows schematically the method according to the invention for producing a micromechanical-optical component.

1. A: Bereitstellen eines Spacer-Wafers mit einer Ausnehmung;
2. B: Bereitstellen eines Bauteilsubstrats mit einem darauf befestigten optischen Halbleiterbauelements;
3. C: Anlegen des Bauteilsubstrats an den Spacer-Wafer derart, dass das optische Halbleiterbauteil in der Ausnehmung angeordnet wird;
4. D: Verbinden des Bauteilsubstrats mit dem Spacer-Wafer durch Schaffen einer ersten stoffschlüssigen Verbindung mittels eines ersten Durchstrahl-Bond-Verfahrensschrittes,
5. E: Anlegen eines Glasdeckels an den Spacer-Wafer derart, dass die Ausnehmung abgedeckt wird;
6. F: Verbinden des Glasdeckels mit dem Spacer-Wafer durch Schaffen einer zweiten stoffschlüssigen Verbindung mittels eines zweiten Durchstrahl-Bond-Verfahrensschrittes;
7. G: Vereinzeln des mikromechanisch-optischen Bauteils durch Sägen des Spacer-Wafers.

The procedure includes the essential steps:

1. A: providing a spacer wafer with a recess;
2. B: providing a component substrate with an optical semiconductor component mounted thereon;
3. C: placing the component substrate on the spacer wafer in such a way that the optical semiconductor component is arranged in the recess;
4. D: connecting the component substrate to the spacer wafer by creating a first material connection by means of a first transmission bonding process step,
5. E: placing a glass cover on the spacer wafer in such a way that the recess is covered;
6. F: connecting the glass cover to the spacer wafer by creating a second material connection by means of a second irradiation bonding process step;
7. G: Separation of the micromechanical-optical component by sawing the spacer wafer.

List of reference symbols

1

optical semiconductor device

2

Component substrate

3

first transmission bonding

4th

Spacer wafer

5

first material connection

6th

Glass lid

7th

second transmission bonding

8th

continuous recess

9

Mirror flank

10

Back contact

12th

first absorption layer

13th

second material connection

14th

second absorption layer

15th

Solder ball

16

Auxiliary wafer

17th

Through hole

18th

doped area

28

cavern

40

Spacers

50

Beam path

160

frame

Claims (15)

Micromechanical-optical component with a glass cover (6), a spacer (40) and a component substrate (2), - the spacer having a recess which forms a cavity (28) which is delimited by the glass cover and the component substrate, - wherein an optical semiconductor component (1) is arranged in the cavern, which is attached to the component substrate and is set up to send optical radiation through the glass cover, - wherein the spacer and the component substrate are connected to one another by means of a first material connection (5) - wherein the glass lid and the spacer are connected to one another by means of a second material connection (13), - wherein a first absorption layer (12) is arranged on the first material connection and a second absorption layer (14) is arranged on the second material connection. Micromechanical-optical component according to Claim 1 , characterized in that the component substrate (2) is a ceramic. Micromechanical-optical component according to one of the preceding claims, characterized in that the first material connection (5) and / or the second material connection (13) is a seal glass bond. Micromechanical-optical component according to one of the preceding claims, characterized in that the cavity (28) is hermetically sealed. Micromechanical-optical component according to one of the preceding claims, characterized in that the first absorption layer (12) is a layer on the component substrate (2). Micromechanical-optical component according to one of the preceding Claims 1 to 5 , characterized in that the second absorption layer (14) is a layer on the glass lid (6). Micromechanical-optical component according to one of the preceding Claims 1 to 5 , characterized in that the second absorption layer (14) is a doped region (18) of the spacer (40). Micromechanical-optical component according to one of the preceding claims, characterized in that at least one frame (160) which surrounds the glass cover (6) and / or the component substrate (2) is arranged on the spacer (40). Process for the production of a micromechanical-optical component with the following steps: A: providing a spacer wafer with a recess; B: providing a component substrate with an optical semiconductor component mounted thereon; C: placing the component substrate on the spacer wafer in such a way that the optical semiconductor component is arranged in the recess; D: connecting the component substrate to the spacer wafer by creating a first material connection by means of a first transmission bonding process step, E: placing a glass cover on the spacer wafer in such a way that the recess is covered; F: connecting the glass cover to the spacer wafer by creating a second material connection by means of a second irradiation bonding process step; G: Separation of the micromechanical-optical component by sawing the spacer wafer. Method for producing an optical component according to Claim 9 , characterized in that the first material connection is produced by seal glass bonding after a seal glass has been applied to the spacer wafer and / or the component substrate. Method for producing an optical component according to Claim 9 or 10 , characterized in that the second material connection is produced by seal glass bonding after a seal glass has been applied to the spacer wafer and / or the glass wafer. Method for producing an optical component according to one of the Claims 9 to 11 , characterized in that, before step C, a first absorption layer is applied to the component substrate. Method for producing an optical component according to one of the Claims 9 to 12th , characterized in that before step E, a second absorption layer is applied to the glass lid. Method for producing an optical component according to one of the Claims 9 to 12th , characterized in that, before step E, a second absorption layer is created on the spacer wafer by doping an area. Method for producing an optical component according to one of the Claims 10 to 15th , characterized in that before step C an auxiliary wafer with a hole is applied to the spacer wafer, and in step C the component substrate is positioned in the hole and / or that before step E an auxiliary wafer with a hole is placed on the spacer wafer Wafer is applied, and in step E the glass lid is positioned in the hole.

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