TWI647741B - Process for microwave stripping epitaxial elements - Google Patents

Abstract

A process for microwave stripping epitaxial elements, comprising: (a) forming a patterned refractory metal layer on an insulating substrate; (b) extruding an epitaxial film on the patterned refractory metal layer; and (c) Providing a microwave from a side facing the insulating substrate in a reduced pressure environment, allowing microwaves to penetrate and absorb the microwave through the patterned refractory metal layer, and forming in the patterned refractory metal layer during absorption and reflection An eddy current to generate a thermal energy to rapidly melt the patterned refractory metal layer, thereby peeling the epitaxial film from the insulating substrate; wherein the thickness of the patterned refractory metal layer and the microwave are less than or equal to Under the premise of damaging the epitaxial film and the insulating substrate, the patterned refractory metal layer is rapidly melted by the thermal energy to peel the epitaxial film from the insulating substrate.

Description

Process for microwave stripping epitaxial elements

The invention relates to a process for stripping an element, in particular to a process for microwave stripping an epitaxial element.

The epitaxial process is generally used as a technical means for stripping III-V photo-electric semiconductor compounds such as gallium nitride (GaN), and the purpose thereof is to produce, for example, a light-emitting diode (LED) or a laser diode. Solid state light-emitting elements such as polar bodies (LD). For example, in the conventional blue light-emitting diodes, a GaN-based luminescent film layer structure is generally formed on a sapphire substrate by metalorganic vapor phase deposition (MOCVD). However, the thermal conductivity of the sapphire substrate is low; therefore, the thermal energy generated by the light-emitting diode during operation can only accumulate on the sapphire substrate, which will result in heat of the light-emitting diode.

In order to solve the problem of insufficient heat dissipation of the sapphire substrate, the person skilled in the art mainly bonds a carrier with a heat transfer rate superior to the sapphire substrate on the luminescent film layer structure, and transmits the laser liftoff. Technology that illuminates the laser light from the side of the sapphire substrate to bond the GaN molecules bound to the side of the sapphire substrate The laser light is cut off from the sapphire substrate by the laser light to be disconnected from the sapphire substrate, thereby solving the problem of insufficient heat dissipation.

The laser lift-off technique allows the luminescent film layer structure to be peeled off from the sapphire substrate; however, the laser light that is irradiated onto the sapphire substrate is a mode that is attributed to spot heating. The laser light irradiated to the sapphire substrate and the luminescent film layer structure in a point heating mode not only causes a problem of concentration of thermal stress which is unpleasant to those skilled in the art at the irradiation place; further, the luminescent film layer is peeled off. The time required for the structure also takes a long time due to the multi-point line and multi-line surface.

According to the above description, it is known that the process of improving the stripping epitaxial element to solve the problem of thermal stress concentration under the premise of reducing the process time is a subject to be solved by those skilled in the art.

Accordingly, it is an object of the present invention to provide a process for a microwave stripping epitaxial element that solves the problem of thermal stress concentration under the premise of reducing process man-hours.

Thus, the process of the microwave stripping epitaxial element of the present invention comprises the following steps: a step (a), a step (b), and a step (c). The step (a) is to form a patterned refractory metal layer on an insulating substrate. In the step (b), an epitaxial film composed of an optoelectronic semiconductor compound is deposited on the patterned refractory metal layer to fill the plurality of openings of the patterned refractory metal layer. The step (c) is to provide a side from the side facing the insulating substrate in a reduced pressure environment. Microwave, allowing the microwave to penetrate and reflect through the patterned refractory metal layer, and forming an eddy current in the patterned refractory metal layer during absorption and reflection to generate a thermal energy to rapidly melt the The refractory metal layer is patterned such that the epitaxial film is peeled off from the insulating substrate and a roughened surface having an apparent shape complementary to the opening of the patterned refractory metal layer is formed on the peeled side of the epitaxial film. In the present invention, the thickness of the patterned refractory metal layer of the step (a) and the time of the microwave provided in the step (c) are equal to or less than the premise that the epitaxial film and the insulating substrate are not damaged. The patterned refractory metal layer is rapidly melted by the thermal energy to peel the epitaxial film from the insulating substrate.

The invention has the effect of: absorbing and reflecting the microwave of the electromagnetic radiation by using the patterned refractory metal layer through the patterned refractory metal layer sandwiched between the insulating substrate and the epitaxial film; Characterizing that the eddy current is formed therein and the thermal energy is generated, and the patterned refractory metal layer is rapidly melted in a short time without damaging the insulating substrate and the epitaxial film to make the epitaxial film from the insulating substrate Stripped.

2‧‧‧Insert substrate

21‧‧‧ side

3‧‧‧ patterned refractory metal layer

30‧‧‧ openings

4‧‧‧Elevation film

41‧‧‧Aluminum nitride layer

411‧‧‧ side

412‧‧‧Rough surface

42‧‧‧Solid light-emitting elements

5‧‧‧bonding layer

6‧‧‧Loading substrate

7‧‧‧Decompression chamber

MW‧‧‧Microwave

Other features and effects of the present invention will be apparent from the following description of the drawings. FIG. 1 is a partial perspective view illustrating the process of the microwave stripping epitaxial element of the present invention. A step (a) of an embodiment; FIG. 2 is a partial perspective view showing a step (b) of the embodiment of the present invention; and FIG. 3 is a partial perspective view showing a step (b') of the embodiment of the present invention. Figure 4 is a partial perspective view showing a step (b") of the embodiment of the present invention; Figure 5 is a front elevational view showing a step (c) of the embodiment of the present invention; Figure 6 is a partial perspective view illustrating The structure obtained after the step (c) of the embodiment is completed; FIG. 7 is a scanning electron microscope (SEM) oblique cross-sectional image, illustrating a process of the microwave stripping epitaxial element of the present invention. Specifically, the SEM oblique cross-sectional image obtained by performing the step (a) is performed; and FIG. 8 is an SEM oblique cross-sectional image illustrating the SEM oblique cross-sectional image obtained by performing the step (b) in the specific example of the present invention.

<Detailed Description of the Invention>

An embodiment of the process of the microwave stripping epitaxial element of the present invention comprises the following steps: a step (a), a step (b), a step (b'), a step (b"), and a step (c) ).

Referring to FIG. 1, the step (a) is to form a patterned refractory metal layer 3 having a plurality of openings 30 on an insulating substrate 2.

Referring to FIG. 2, the step (b) is to deposit an epitaxial film 4 composed of an optoelectronic semiconductor compound on the patterned refractory metal layer 3 to fill the openings 30 of the patterned refractory metal layer 3. Preferably, the epitaxial film 4 has an aluminum nitride (AlN) layer 41 from the patterned refractory metal layer 3 facing the insulating substrate 2, and a nitrogen layer deposited on the aluminum nitride layer 41. A gallium-based solid state light-emitting element 42. It should be noted that, in the case of GaN, for example, a solid-state light-emitting element such as an LED is known. The basic film structure of the solid-state light-emitting element 42 of the present invention is such that an n-type GaN is sequentially facing away from the insulating substrate 2. (n-GaN) layer, a multiple quantum well (MQW) multilayer film, and a p-type GaN (p-GaN) layer. To simplify the contents of FIG. 2, applicants present in a manner that omits the aforementioned n-GaN layer, MQW multilayer film, and p-GaN layer.

Referring to FIG. 3 and FIG. 4, the step (b') is to form a bonding layer on the epitaxial film 4; the step (b") is to bond a bearing on the bonding layer 5. The substrate 6. The bonding layer 5 of the present invention is composed of a metal material, and the carrier substrate 6 suitable for the step (b") of the embodiment of the present invention may be copper (Cu) or copper alloy having a high heat transfer rate. And the like; in addition, the step (b") is also referred to as a wafer bonding step. Therefore, when the step (b") is performed, the crystal is obtained by means of hot pressing. Round bonding step. This step (b') and the step (b") are not the technical points of the present invention, and will not be further described herein.

Referring to FIG. 5 and FIG. 6, the step (c) is to provide a microwave MW from a side 21 facing the insulating substrate 2 in a decompression environment of a decompression chamber 7, so that the microwave MW is worn. The insulating substrate 2 is absorbed and reflected by the patterned refractory metal layer 3, and an eddy current (not shown) is formed in the patterned refractory metal layer 3 during absorption and reflection to generate a thermal energy to rapidly The patterned refractory metal layer 3 is melted, and the epitaxial film 4 is peeled off from the insulating substrate 2, and a peeled side 411 of the epitaxial film 4 is formed with an appearance shape complementary to the patterned refractory metal layer 3. The rough surface 412 of the openings 30. In the present invention, the thickness of the patterned refractory metal layer 3 of the step (a) and the time of the microwave MW provided in the step (c) are equal to or less than sufficient to damage the epitaxial film 4 and the insulating substrate. 2, the patterned refractory metal layer 3 is rapidly melted by the thermal energy to peel the epitaxial film 4 from the insulating substrate 2, after the step (c) is performed, after peeling off The epitaxial film 4 is carried on the carrier substrate 6.

It should be additionally noted that the epitaxial film 4 carried on the carrier substrate 6 is further flipped by 180° (see FIG. 6) after the step (c) is performed to make the rough surface 412. A light-emitting surface of the epitaxial film 4 is formed, and a component process and a chip dicing process are sequentially applied to obtain a plurality of LED dies (not shown). Therefore, using the rough surface 412 as the light exit surface of the epitaxial film 4 not only helps to reduce the total reflection of the light source emitted from the multi-quantum well (MQW) multilayer film, but also enhances the light extraction rate of the epitaxial film 4. It also provides scattering of the light source to improve the uniformity of the light source.

The patterned refractory metal layer 3 suitable for use in the present invention is made of a metal material selected from the group consisting of molybdenum (Mo), tungsten (W), and tantalum (Ta). Here It should be added that what is called refractory metal, as the name implies, is that refractory metal has the ability to resist high temperature and corrosion, its melting point is usually higher than 2000 ° C, and its high temperature chemical stability is good for resisting high temperature creep ( It is characterized by high hardness and high temperature in normal temperature environment.

It should be additionally noted here that the main reason why the patterned refractory metal layer 3 is required in the present invention is that after the patterned refractory metal layer 3 described in the step (a) is implemented, the patterned refractory metal layer is patterned. 3 is further disposed in a MOCVD furnace tube (not shown) to deflect the epitaxial film 4 in a high temperature environment approaching 1000 °C. Therefore, on the one hand, the high temperature stability of the patterned refractory metal layer 3 can be resisted against the high temperature environment in which the step (b) is located; on the other hand, the patterned refractory metal layer 3 can also be used for the microwave MW of the electromagnetic radiation. The eddy current (not shown) formed by characteristics such as absorption and reflection rapidly causes the thermal energy to melt the patterned refractory metal layer 3, thereby peeling the epitaxial film 4 from the insulating substrate 2. In addition, the patterned refractory metal layer 3 can reduce the contact area between the epitaxial film 4 and the insulating substrate 2, and can also cause a step on the insulating substrate 2. Therefore, on the one hand, the problem of lattice mismatch can be reduced due to the decrease of the contact area, and on the other hand, the epitaxial film can be lowered by epitaxial lateral overgrowth by the step. Threading dislocation. In this embodiment of the invention, the patterned refractory metal layer 3 is made of molybdenum which constitutes the components within the reaction chamber of the MOCVD furnace tube.

Moreover, the high temperature stability of the aluminum nitride layer 41 based on the epitaxial film 4 is good; therefore, the embodiment of the present invention allows the patterned refractory metal layer 3 to directly contact the aluminum nitride layer 41, thereby avoiding the patterned fire resistance. The metal atoms in the metal layer 3 are diffused upward by the high temperature environment of the MOCVD furnace tube (not shown) to the GaN-based solid-state light-emitting element 42 of the epitaxial film 4, resulting in The result of unsatisfactory people in the technical field.

It should be additionally noted here that when the thickness of the patterned refractory metal layer 3 is greater than 40 nm, more epitaxial engineering is required to compensate for the topographic difference; in addition, when the time of the microwave MW of the step (c) is greater than 1 ms , the heating time will be too long to destroy the element epitaxial layer. Therefore, preferably, the thickness of the patterned refractory metal layer 3 of the step (a) is 40 nm or less, and the time of the microwave MW supplied to the step (c) is 1 ms or less. More preferably, the output power of the microwave MW provided in the step (c) is between 100 W and 5000 W.

<Specific example>

A specific example of the process of the microwave stripping epitaxial element of the present invention is carried out according to the above embodiment, and the bonding layer 5 and the wafer key are described based on the steps (b') and (b") of the embodiment. The technique is not the technical focus of the present invention; therefore, the detailed process and result of this specific example is to omit the steps (b') and (b)) and briefly describe the following.

First, a mask layer is disposed on a sapphire substrate and sputtered on the sapphire substrate provided with the mask layer. A patterned molybdenum metal layer having a thickness of 40 nm and having a plurality of openings arranged in an array arrangement is deposited to complete a patterned refractory metal layer of the specific example of the present invention. After the patterned molybdenum metal layer is deposited, the mask layer is removed. It can be seen from the SEM oblique cross-sectional image shown in FIG. 7 that the openings of the patterned molybdenum metal layer are circular holes having a diameter of about 2.0 μm, and the openings are arranged in an array of a regular triangular shape.

The sapphire substrate on which the patterned molybdenum metal layer is formed is placed in an MOCVD furnace tube to deposit an epitaxial film mainly composed of gallium nitride (GaN) on one of the specific examples of the present invention on the patterned molybdenum metal layer. As can be seen from the SEM oblique cross-sectional image shown in FIG. 8, the thickness of the epitaxial film and the patterned molybdenum metal layer of this specific example of the present invention are about 7 μm and 40 nm, respectively.

Finally, the sapphire substrate having the epitaxial film is provided with a microwave having an output power of 3500 W to 5000 W for about 1 ms from a side facing the sapphire substrate in a decompression environment of 60 to 100 Pa, so that the microwave is worn. Passing through the sapphire substrate and absorbing and reflecting through the patterned molybdenum metal layer, and generating an eddy current in the patterned molybdenum metal layer during absorption and reflection to generate thermal energy to rapidly melt the patterned molybdenum metal layer The epitaxial film is peeled off from the sapphire substrate.

In summary, the process of the microwave stripping epitaxial element of the present invention passes through the patterned refractory metal layer 3 which is sandwiched between the insulating substrate 2 and the epitaxial film 4 to be thin enough to utilize the patterned refractory metal layer. 3 absorbing and reflecting the microwave MW of the electromagnetic radiation to form the eddy current therein and generating the thermal energy without damaging the insulation On the premise of the substrate 2 and the epitaxial film 4, the patterned refractory metal layer 3 is rapidly melted in a short time to peel the epitaxial film 4 from the insulating substrate 2 and the process time is reduced, so that the present invention can be achieved. the goal of.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the simple equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still Within the scope of the invention patent.

Claims (6)

A process for microwave stripping epitaxial elements, comprising the steps of: (a) forming a patterned refractory metal layer on an insulating substrate; and a step (b) of stretching the patterned refractory metal layer Forming an epitaxial film formed of an optoelectronic semiconductor compound to fill a plurality of openings of the patterned refractory metal layer; and a step (c) of providing a microwave from a side facing the insulating substrate in a reduced pressure environment Passing the microwave through the insulating substrate to absorb and reflect through the patterned refractory metal layer, and forming an eddy current in the patterned refractory metal layer during absorption and reflection to generate a thermal energy to rapidly melt the pattern. The refractory metal layer is peeled off from the insulating substrate, and a rough surface having an appearance shape complementary to the opening of the patterned refractory metal layer is formed on the peeled side of the epitaxial film; wherein, the step a) the thickness of the patterned refractory metal layer and the time of the microwave provided in the step (c) is equal to or less than that sufficient to prevent the epitaxial film and the insulating substrate from being damaged The metal layer is rapidly melted by the thermal energy to peel the epitaxial film from the insulating substrate. The process for microwave stripping epitaxial elements according to claim 1, wherein the patterned refractory metal layer is made of a metal material selected from the group consisting of molybdenum, tungsten, and rhenium. The process of the microwave stripping epitaxial element according to claim 2, wherein the thickness of the patterned refractory metal layer of the step (a) is 40 nm or less, and the time of the microwave provided in the step (c) is less than Equal to 1 ms. The process of the microwave stripping epitaxial element according to claim 3, wherein the output power of the microwave provided in the step (c) is between 100 W and 5000 W. The process of the microwave stripping epitaxial element according to claim 3, wherein the epitaxial film has an aluminum nitride layer from the patterned refractory metal layer facing the insulating substrate, and a layer is formed on the nitriding layer. A solid-state light-emitting element based on gallium nitride in the aluminum layer. The process of the microwave stripping epitaxial element according to claim 3, further comprising a step (b') and a step (b) between the step (b) and the step (c), the step ( b') is to form a bonding layer on the epitaxial film, and the step (b") is to bond a carrier substrate on the bonding layer, after the step (c) is performed, after being stripped The epitaxial film is carried on the carrier substrate.