阅读说明：本技术 垂直腔面发射激光器 (Vertical cavity surface emitting laser ) 是由 王光辉 王青 赵风春 江蔼庭 吕朝晨 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种垂直腔面发射激光器。该垂直腔面发射激光器包括：衬底；在衬底上依次生长的N接触层、N-DBR层、MQW层、氧化层、P-DBR层、P接触层；以及N电极、P电极和SiN钝化层；N电极设在N接触层上,P电极设在P接触层上,SiN钝化层覆盖垂直腔面发射激光器的至少部分表面上；其中,衬底上具有多个通孔,衬底的背面具有覆盖通孔的金属层,金属层的下表面形成有金属凸点；通孔内设有金属柱,金属凸点通过金属柱连接至N电极和P电极。该垂直腔面发射激光器采用衬底背面同侧电极设计,可直接在硅基材料表面进行焊接,避免了传统工艺造成的空间浪费,易于实现光电子器件集成。(The invention discloses a vertical cavity surface emitting laser. The vertical cavity surface emitting laser includes: a substrate; an N contact layer, an N-DBR layer, an MQW layer, an oxide layer, a P-DBR layer and a P contact layer which are grown on the substrate in sequence; and an N electrode, a P electrode and a SiN passivation layer; the N electrode is arranged on the N contact layer, the P electrode is arranged on the P contact layer, and the SiN passivation layer covers at least part of the surface of the vertical cavity surface emitting laser; the substrate is provided with a plurality of through holes, the back surface of the substrate is provided with a metal layer covering the through holes, and the lower surface of the metal layer is provided with metal bumps; and a metal column is arranged in the through hole, and the metal salient point is connected to the N electrode and the P electrode through the metal column. The vertical cavity surface emitting laser adopts the design of electrodes on the same side of the back surface of the substrate, can directly weld on the surface of a silicon-based material, avoids space waste caused by the traditional process, and is easy to realize photoelectronic device integration.)

1. A vertical cavity surface emitting laser, comprising:

a substrate;

an N contact layer, an N-DBR layer, an MQW layer, an oxide layer, a P-DBR layer and a P contact layer which are grown on the substrate in sequence;

the N electrode is arranged on the N contact layer;

the P electrode is arranged on the P contact layer;

a SiN passivation layer covering at least a portion of a surface of the VCSEL;

the substrate is provided with a plurality of through holes, the back surface of the substrate is provided with a metal layer covering the through holes, and metal bumps are formed on the lower surface of the metal layer; and a metal column is arranged in the through hole, and the metal salient point is connected to the N electrode and the P electrode through the metal column.

2. A vertical cavity surface emitting laser according to claim 1, wherein said substrate is a GaAs substrate.

3. A vertical cavity surface emitting laser according to claim 1, wherein said substrate has a thickness of 140 to 160 μm.

4. A vertical cavity surface emitting laser according to claim 1, wherein said metal layer has a thickness of 0.5 to 1.5 μm.

5. A vertical cavity surface emitting laser according to claim 1, wherein said metal bump has a height of 30 to 60 μm.

6. A vertical cavity surface emitting laser according to claim 1, wherein said metal layer, said metal posts, and said metal bumps are made of gold.

7. The VCSEL of claim 1, wherein a metal trace is disposed on the SiN passivation layer, the metal trace connecting the P electrode and the metal pillar.

8. A vertical cavity surface emitting laser according to claim 1, wherein said through hole is formed by ICP etching said substrate.

9. A vertical cavity surface emitting laser according to claim 1, wherein said metal bump is formed by applying a photoresist to said metal layer and said substrate backside, and further by a negative resist lift-off technique.

Technical Field

The present invention relates to the field of optoelectronic devices, and in particular, to vertical cavity surface emitting lasers.

Background

Because of the characteristic that the Vertical Cavity Surface Emitting Laser (VCSEL) emits laser light perpendicular to the substrate surface, the VCSEL can be widely applied to integrated optoelectronic technical schemes such as silicon optical integration and the like, a substrate of a VCSEL device can be fixed on a silicon-based structure in a bonding mode, and the electrical connection with a substrate is realized in a mode of combining die bonding and wire bonding when the VCSEL device is packaged in the current VCSEL structure design, and the electrical connection mode is not easy to realize the integration of the optoelectronic devices on the silicon substrate. Thus, existing VCSEL structure designs remain to be improved.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, one objective of the present invention is to provide a vertical cavity surface emitting laser, which adopts a design of electrodes on the same side of the back surface of a substrate, can directly perform welding on the surface of a silicon-based material, avoids space waste caused by the conventional process, and is easy to realize optoelectronic device integration.

In one aspect of the invention, a vertical cavity surface emitting laser is presented. According to an embodiment of the present invention, the vertical cavity surface emitting laser includes: a substrate; an N contact layer, an N-DBR layer, an MQW layer, an oxide layer, a P-DBR layer and a P contact layer which are grown on the substrate in sequence; the N electrode is arranged on the N contact layer; the P electrode is arranged on the P contact layer; a SiN passivation layer covering at least a portion of a surface of the VCSEL; the substrate is provided with a plurality of through holes, the back surface of the substrate is provided with a metal layer covering the through holes, and metal bumps are formed on the lower surface of the metal layer; and a metal column is arranged in the through hole, and the metal salient point is connected to the N electrode and the P electrode through the metal column.

According to the vertical cavity surface emitting laser provided by the embodiment of the invention, the metal bumps respectively connected to the P electrode and the N electrode of the device are arranged on the back surface (namely the surface of the side far away from the N contact layer) of the substrate, so that the design of the same back surface electrode of the vertical cavity surface emitting laser is realized. The vertical cavity surface emitting laser with the metal salient points can be directly welded on the surface of a silicon-based material by reflow soldering, so that the bonding process is simplified, the space waste caused by the traditional process is avoided, and the integration of optoelectronic devices is easy to realize. In addition, the metal columns are arranged in the through holes in the substrate, and the heat dissipation efficiency of the device can be improved.

In addition, the vertical cavity surface emitting laser according to the above embodiment of the present invention may further have the following additional technical features:

in some embodiments of the invention, the substrate is a GaAs substrate.

In some embodiments of the present invention, the substrate has a thickness of 140 to 160 μm.

In some embodiments of the present invention, the thickness of the metal layer is 0.5 to 1.5 μm.

In some embodiments of the present invention, the height of the metal bump is 30-60 μm.

In some embodiments of the present invention, the metal layer, the metal pillar, and the metal bump are made of gold.

In some embodiments of the present invention, a metal trace is disposed on the SiN passivation layer, and the metal trace connects the P electrode and the metal pillar.

In some embodiments of the invention, the via is formed by ICP etching the substrate.

In some embodiments of the present invention, the metal bump is formed by applying a photoresist on the metal layer and the back surface of the substrate, and further by a negative photoresist lift-off technique.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic cross-sectional view of a VCSEL according to an embodiment of the invention;

fig. 2 is a schematic diagram of a method for forming a metal bump by negative stripping.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In one aspect of the invention, a vertical cavity surface emitting laser is presented. Referring to fig. 1, according to an embodiment of the present invention, the vertical cavity surface emitting laser includes: a substrate 1; an N contact layer 2, an N-DBR layer 4, an MQW layer 6, an oxide layer 7, a P-DBR layer 8 and a P contact layer 9 which are grown on a substrate 1 in sequence; and an N electrode 3, a P electrode 10 and a SiN passivation layer 5; the N electrode 3 is arranged on the N contact layer 2, the P electrode 10 is arranged on the P contact layer 9, and the SiN passivation layer 5 covers at least part of the surface of the vertical cavity surface emitting laser; the substrate 1 is provided with a plurality of through holes 11, the back surface of the substrate 1 is provided with a metal layer 12 covering the through holes 11, and the lower surface of the metal layer 12 is provided with a metal bump 13; the through holes are internally provided with metal columns, and the metal bumps 13 are connected to the N electrodes 3 and the P electrodes 10 through the metal columns.

According to the vertical cavity surface emitting laser provided by the embodiment of the invention, the metal bumps respectively connected to the P electrode and the N electrode of the device are arranged on the back surface (namely the surface of the side far away from the N contact layer) of the substrate, so that the design of the same back surface electrode of the vertical cavity surface emitting laser is realized. The vertical cavity surface emitting laser with the metal salient points can be directly welded on the surface of a silicon-based material by reflow soldering, so that the bonding process is simplified, the space waste caused by the traditional process is avoided, and the integration of optoelectronic devices is easy to realize. In addition, the metal columns are arranged in the through holes in the substrate, and the heat dissipation efficiency of the device can be improved.

The vertical cavity surface emitting laser according to an embodiment of the present invention is further described in detail below.

According to some embodiments of the invention, the substrate 1 is a GaAs substrate.

According to some embodiments of the present invention, the thickness of the substrate 1 may be 140 to 160 μm, such as 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, and the like. By controlling the thickness of the substrate 1 within the above range, the thickness of the substrate 1 is small, which can further facilitate the formation of the through hole 11 in the substrate 1 and the heat dissipation of the device.

According to some embodiments of the present invention, the thickness of the metal layer 12 may be 0.5 to 1.5 μm, such as 0.5 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, and the like. If the thickness of the metal layer 12 is too low, the gold layer may fall off and the heat dissipation performance may be poor; if the metal layer 12 is obtained with too high a thickness, it may affect the subsequent electroplating process and lead to waste of precious metals.

According to some embodiments of the present invention, the height of the metal bump 13 may be 30 to 60 μm, such as 30 μm, 40 μm, 50 μm, 60 μm, and the like. If the height of the metal bump 13 is too low, an effective connection cannot be formed during subsequent welding with the substrate, so that an open circuit can be caused; if the height of the metal bump 13 is too large, the metal bump may be detached or the chip may be lifted up in a subsequent soldering process, and rework operation is not possible.

According to some embodiments of the present invention, the metal layer, the metal pillar, and the metal bump are made of gold.

According to some embodiments of the present invention, a metal trace is disposed on the SiN passivation layer 5, and the metal trace connects the P electrode 10 and the metal pillar. Specifically, the metal trace may be formed on the SiN passivation layer by electroplating.

For ease of understanding, a method of manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention is described below.

(1) Forming an N contact layer, an N-DBR layer, an MQW layer, an oxide layer, a P-DBR layer and a P contact layer in sequence from bottom to top according to a layered structure on a GaAs semi-insulating substrate by utilizing an MOCVD (metal organic chemical vapor deposition) epitaxial growth method; the N contact layer is used for forming an N-type ohmic contact, the MQW layer is used as a luminous area when being leased, the oxide layer is used for limiting current and light, the N-DBR layer and the P-DBR layer are used for forming a reflecting mirror, and the P contact layer is used for forming a P-type ohmic contact.

(2) Preparing a P electrode on the P contact layer by utilizing a photoresist stripping technology to form a P-type ohmic contact;

(3) etching the epitaxial layer to an oxide layer by utilizing an ICP (inductively coupled plasma) etching technology, and performing wet oxidation by utilizing an oxidation furnace to complete the preparation of the oxide layer;

(4) etching the epitaxial layer to the N contact layer by utilizing an ICP (inductively coupled plasma) etching technology;

(5) preparing an N electrode by using a photoresist stripping technology and annealing to form N-type ohmic contact; depositing a SiN film by using a PECVD (plasma enhanced chemical vapor deposition) technology, forming a mask pattern of a corresponding passivation layer by using a photoetching technology, and finally etching the SiN film to form the passivation layer; the passivation layer is used for protecting the side wall of the chip and realizing electrical isolation and leakage protection;

(6) thinning the substrate to 140-160 mu m, and etching the substrate from the front side to the back side of the substrate at a preset position of the substrate by utilizing an ICP (inductively coupled plasma) etching technology to form a through hole;

(7) utilizing electroplating technology to lead P, N metal electrode to the back of the substrate, covering the through hole structure, and forming metal column;

(8) sputtering a metal layer on the back of the substrate to connect the metal column, coating the photoresist 14 on the basis of the metal layer, and performing a negative photoresist stripping and bumping process (refer to fig. 2) to obtain the vertical cavity surface emitting laser.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.