TWI515772B - Manufacturing method for forming substrate with silicon-germanium epitaxial layer - Google Patents

Description

Method for manufacturing substrate with germanium epitaxial crystal

The present invention relates to a method for fabricating a substrate having a germanium epitaxial layer, and more particularly to a method for forming a germanium epitaxial layer on a substrate by electrochemical methods.

矽锗(SiGe) epitaxy is one of the most important emerging technologies in recent years. 矽锗 晶 has a relatively large energy gap and a large electron/hole mobility, which can generate a large driving current, so it is suitable for Miniaturized electronic or optoelectronic components and further improved component characteristics.

Since the radius of the germanium atom is larger than the radius of the germanium atom, and the lattice constant of pure germanium is about 5.65Å, the lattice constant of pure germanium is 5.43Å, so when the germanium atom replaces the partial atom, it enters the germanium. In the lattice, because the lattice mismatch between 锗 and 矽, the overall lattice structure is distorted, and the distorted lattice structure makes the crystal lattice distortion when the density of the charge carriers is the same. The electron/hole mobility rate is increased by about 5 to 10 times compared with the single crystal germanium, so that the component resistance value can be lowered, the performance of the electronic component or the photovoltaic component can be improved, the operation speed can be faster, and the integrated circuit can be improved. The integration of the next generation of electronic products and optoelectronic products.

However, the conventional technique of growing the epitaxial layer is more than the epitaxial growth of the epitaxial layer on the germanium substrate. The growth time required for this method is long, and the surface roughness of the epitaxial layer is large and easy. If the elliptical layer is damaged by the gradual change of the component, and the desired strain relaxation effect is required, the thickness of the epitaxial layer to be formed may be too thick, in addition to the inconvenience of application. The time required for its preparation is too long to be easily produced in large quantities.

Therefore, there is a need for a method for preparing a germanium epitaxial layer having a thickness of less than 100 nm, which is low in cost and simple in steps, so as to improve the long-term growth time of the conventional germanium epitaxial crystal and the surface roughness of the epitaxial layer. Improve the applicability of germanium epitaxial in electronic components or optoelectronic components.

The invention provides a method for manufacturing a substrate with a germanium epitaxial layer. The formed germanium epitaxial layer has the characteristics of compactness, low defect, thin thickness, and the like, and the process is simple, and can be applied to the high carrier migration path. A starting material for a photovoltaic element of a crystal, a gold oxide semi-transistor, or a tri-five semiconductor.

The object of the present invention is to provide a method for manufacturing a substrate having a germanium epitaxial layer, the method comprising: (A) providing a first substrate, the first substrate comprising a germanium epitaxial layer and a germanium layer Wherein the germanium epitaxial layer is formed on the germanium layer; a second substrate is provided, the second substrate is in direct contact with the germanium epitaxial layer of the first substrate; (B) performing an electrochemical Reacting to convert the ruthenium layer of the first substrate into a porous ruthenium layer; and (C) removing the porous ruthenium layer.

According to an embodiment of the present invention, in the step (A), the method further includes a step (A1) of heating the first substrate and the second substrate to make the germanium epitaxial layer of the first substrate and the second The substrate is bonded. Wherein, in the step (A1), the heating temperature is 300 ° C or higher, preferably 300 ° C to 700 ° C.

In the method for manufacturing a substrate having a germanium epitaxial layer according to the present invention, the first substrate in the step (A) is a doped germanium layer and is doped with a group IIIA or VA element. The ruthenium layer is preferably further, and the ruthenium layer doped with an element such as boron, aluminum or gallium is more preferable. In addition, in the step (A), the germanium epitaxial layer is Si _1-X Ge _X , wherein 0<X<1, preferably 0<X≦0.5, and the thickness of the germanium epitaxial layer is 200 nm or less, preferably 50 nm to 200 nm.

According to the method for manufacturing a substrate having a germanium epitaxial layer according to the present invention, in the step (A), the second substrate is selected from the group consisting of a germanium substrate, a glass substrate, a metal substrate, a ceramic substrate, and a plastic substrate. The present invention is not limited thereto, and according to a preferred embodiment of the present invention, the second substrate may further comprise at least one selected from the group consisting of a hafnium oxide layer (SiO ₂ ) and a tantalum nitride layer ( a group consisting of Si ₃ N ₄ ) on at least one surface of the second substrate, and in the step (A), the yttrium oxide layer or the tantalum nitride layer and the lanthanum in the first substrate The epitaxial layer is in direct contact.

According to the invention, there is provided a method for manufacturing a substrate having a germanium epitaxial layer. In the step (B), the electrochemical reaction is an anodizing reaction, wherein the anodizing reaction is in a mixed solution of hydrofluoric acid and ethanol. The reaction is carried out at a voltage of 5 volts to 100 volts, and the reaction time is about 0.1 to 10 hours. And the ruthenium layer of the first substrate is converted by anodization reaction In the case of a porous tantalum layer, the pores of the porous tantalum layer have a diameter of between 10 nm and 1000 nm, preferably between 20 nm and 100 nm (please provide a preferred range).

Further, in the step (C), the porous tantalum layer is removed using an alkaline etching solution to expose the tantalum epitaxial layer of the first substrate, wherein the alkaline etching liquid is at least selected A group consisting of Tetramethylammonium hydroxide (TMAH), sodium hydroxide (NaOH), and potassium hydroxide (KOH), of which tetramethylammonium hydroxide is preferred. The alkaline etching solution has a concentration of 0.000001 to 1 M, preferably 0.001 to 0.01 M. The alkaline etching solution selectively removes the porous germanium layer, and after the porous germanium layer is removed, the completed substrate having the germanium epitaxial layer includes a second substrate and a germanium epitaxial layer a layer, or, in the case where the second substrate further comprises a tantalum oxide layer or a tantalum nitride layer, in the substrate having the tantalum epitaxial layer, the tantalum epitaxial layer is formed on the tantalum oxide layer On the layer or the tantalum nitride layer, however, the current technology for growing the germanium epitaxial layer is more than the germanium epitaxial layer grown on the germanium substrate, so the method for manufacturing the substrate having the germanium epitaxial layer according to the present invention A substrate having a germanium epitaxial layer on the insulating layer can be formed.

According to the method for fabricating a substrate having a germanium epitaxial layer, the method further includes a step (D) of oxidizing the germanium epitaxial layer to form a germanium oxide layer on the germanium epitaxial layer. . The oxidation process of the step (D) may change the composition ratio between the tantalum and the tantalum in the tantalum epitaxial layer to increase the content of the tantalum epitaxial layer, and the tantalum epitaxial layer after the oxidation is Si _{1- Y} Ge _Y , wherein Y is greater than X, and Y is in the range of 0 < Y ≦ 1, preferably in the range of 0.5 < Y ≦ 1 and an oxidation process can form a ruthenium oxide layer on the ruthenium epitaxial layer, the oxidation The layer can be used as an insulating layer or a protective layer in the device, and the epitaxial layer can be thinned at the same time, and the thickness of the epitaxial layer can be reduced, thereby preparing a thin strain with an ideal strain relaxation effect. Crystal layer.

According to the present invention, the composition ratio between ruthenium and iridium in the ruthenium epitaxial layer can be controlled by the oxidation procedure described in the step (D), and the ruthenium in the ruthenium epitaxial layer with the degree of oxidation The content is gradually reduced, and the content of antimony is gradually increased. After increasing the antimony content, the epitaxial layer having a high antimony content can have a narrow energy gap width and a large absorption coefficient. For applications such as high concentration solar cells, Can greatly improve its operational performance. Therefore, the method for fabricating a substrate having a germanium epitaxial layer provided by the present invention can change the characteristics of the germanium epitaxial layer (such as the energy gap width) by controlling the degree of oxidation of the germanium epitaxial layer. The movement rate of the electron/hole, etc.). In addition, the manufacturing method described in the present invention is simple, and the cost and the time of preparation can be reduced, and a high-quality germanium epitaxial wafer can be provided, thereby greatly increasing the field of application thereof.

11‧‧‧First substrate

13‧‧‧second substrate

121‧‧‧矽

141, 142‧‧‧矽锗 矽锗 layer

16‧‧‧Oxide layer

18‧‧‧矽 substrate

122‧‧‧Porous layer

22‧‧‧Oxide layer

10,20‧‧‧substrate

1 is a cross-sectional view showing the structure of a first substrate and a second substrate in accordance with a preferred embodiment of the present invention.

2 is a schematic cross-sectional view showing a first substrate and a second substrate joined to each other in a preferred embodiment of the present invention.

3 is a cross-sectional view showing a structure in which a boron-doped germanium layer is anodized to convert a germanium layer into a porous germanium layer in a preferred embodiment of the present invention. Figure.

Figure 4 is a cross-sectional view showing the structure of the porous crucible layer removed using an alkaline etching solution in a preferred embodiment of the present invention.

Figure 5 is a cross-sectional view showing the structure of a germanium epitaxial layer in an oxidized substrate in another preferred embodiment of the present invention.

In the following, examples will be provided to explain in detail embodiments of the invention. Other advantages and utilities of the present invention will be more apparent from the teachings of the present invention. It should be noted that the drawings are simplified in the drawings, and the components, shapes, and sizes shown in the drawings may be modified according to actual conditions. Other variations and modifications can be made without departing from the spirit and scope of the invention as defined in the invention.

[Example 1]

1-4 are diagrams showing a method of fabricating a substrate having a germanium epitaxial layer in accordance with an embodiment of the present invention. As shown in FIG. 4, the substrate 10 includes a tantalum substrate 18, a tantalum oxide layer 16 formed on the tantalum substrate 18, and a tantalum epitaxial layer 141 formed on the tantalum oxide layer 16.

1 is a cross-sectional view showing a structure of a first substrate 11 and a second substrate 13, wherein the first substrate 11 includes a germanium layer 121 and a germanium epitaxial layer 141, and the germanium layer 121 shown in the drawing has a thickness of 625 μm. And consists of boron-doped ruthenium. However, the thickness of the germanium layer 121 and its dopant are not limited thereto, and may be a layer of IIIA or VA (such as boron, aluminum, gallium, etc.) doped with a thickness of 200 μm to 1000 μm. In addition, the germanium epitaxial layer 141 shown in the figure is Si _0.8 Ge _0.2 and has a thickness of 120 nm. However, in other embodiments, the germanium epitaxial layer 141 has a ratio of germanium to germanium. Without being limited thereto, the thickness of the germanium epitaxial layer 141 may be 20 nm to 200 nm. The second substrate 13 includes a tantalum oxide layer 16 and a tantalum substrate 18, and the tantalum oxide layer 16 is formed on one surface of the tantalum substrate 18, and the tantalum oxide layer 16 has a thickness of 200 nm. However, in other embodiments of the present invention, the germanium substrate 18 may be a substrate composed of other materials, such as a glass substrate, a metal substrate, a ceramic substrate, a plastic substrate, etc., and the germanium oxide layer 16 may be in some states. The sample may be omitted or a tantalum nitride layer may be used.

2 is a schematic cross-sectional view showing the first substrate 11 and the second substrate 13 joined to each other, wherein the germanium epitaxial layer 141 is in direct contact with the tantalum oxide layer 16 and annealed under a nitrogen atmosphere at a temperature of 300 ° C for 6 hours. The germanium epitaxial layer 141 is bonded to the hafnium oxide layer 16. However, in other embodiments of the invention, the tantalum epitaxial layer 141 and the hafnium oxide layer 16 may be bonded to each other via a pressurized manner.

3 is a cross-sectional view showing the structure in which the boron-doped tantalum layer 121 is anodized to convert the tantalum layer 121 into the porous tantalum layer 122. In the present embodiment, the anodizing reaction was performed by immersing the ruthenium layer 121 in a mixed solution of 49% hydrofluoric acid and ethanol in a volume ratio of 4:1, and applying a voltage of 40 volts for a reaction time of 8 hours.

4 is a cross-sectional view showing the structure in which the porous tantalum layer 122 is removed using an alkaline etching solution. In this embodiment, the alkaline etching solution used is tetramethylammonium hydroxide (TMAH), and the porous germanium layer 122 can be selectively etched. The germanium epitaxial layer 141 is exposed. As shown in FIG. 4, the substrate 10 having a germanium epitaxial layer completed in this embodiment includes a germanium substrate 18, a tantalum oxide layer 16 formed on the germanium substrate 18, and a germanium layer formed on the tantalum oxide layer 16.锗 晶 layer 141.

[Embodiment 2]

Figure 5 is a diagram showing a method of fabricating another substrate having a germanium epitaxial layer in accordance with an embodiment of the present invention. As shown in FIG. 5, the substrate 20 includes a germanium substrate 18, a tantalum oxide layer 16 formed on the germanium substrate 18, a germanium epitaxial layer 142 formed on the tantalum oxide layer 16, and an epitaxial layer formed on the tantalum layer. Oxide layer 22 on 142. The substrate 20 having the germanium epitaxial layer shown in FIG. 5 is formed by oxidizing the germanium epitaxial layer 141 in the substrate 10 shown in FIG. 4. In the present embodiment, the oxidation step is performed at 900 ° C. Annealed for 10 hours in a pure oxygen atmosphere. In the oxidation process, the ratio of germanium to germanium in the germanium epitaxial layer 141 shown in FIG. 4 varies with the degree of oxidation, wherein the germanium content is gradually increased, and the thickness thereof is gradually decreased to The tantalum epitaxial layer 142 shown in FIG. 5 is formed. The composition of the germanium epitaxial layer 142 shown in the figure is Si _1-y Ge _y , where y>0.5 and has a thickness of 80 nm or less. However, in other embodiments, the germanium epitaxial layer 142 is germanium. The content ratio with ruthenium is not limited thereto, and the thickness of the ruthenium epitaxial layer 141 may be 20 nm to 200 nm. The oxide layer 22 shown in the drawing is a tantalum oxide having a thickness of 200 nm, whereas in other embodiments, the oxide layer 22 may have a thickness of 50 nm to 200 nm.

The above embodiments are merely examples for the convenience of the description, and the scope of the claims should be based on the scope of the patent application, and It is not limited to the above embodiment.

11‧‧‧First substrate

13‧‧‧second substrate

121‧‧‧矽

141, 142‧‧‧矽锗 矽锗 layer

16‧‧‧Oxide layer

18‧‧‧矽 substrate

122‧‧‧Porous layer

22‧‧‧Oxide layer

10,20‧‧‧substrate

Claims (15)

A method for manufacturing a substrate having germanium epitaxial crystals, comprising: (A) providing a first substrate, the first substrate comprising a germanium epitaxial layer and a germanium layer, wherein the germanium epitaxial layer is formed Providing a second substrate, the second substrate is in direct contact with the germanium epitaxial layer of the first substrate; (B) performing an electrochemical reaction to make the germanium layer of the first substrate Converting to a porous layer; and (C) removing the porous layer. The method of claim 1, wherein the step (A) further comprises a step (A1) of heating the first substrate and the second substrate to cause the germanium epitaxial layer of the first substrate Bonded to the second substrate. The method of claim 2, wherein in the step (A1), the heating temperature is from 300 ° C to 700 ° C. The method of claim 1, wherein in the step (A), the ruthenium layer of the first substrate is a doped ruthenium layer. The method of claim 1, wherein in the step (A), the ruthenium layer of the first substrate is a ruthenium layer doped with a group IIIA or VA group. The method of claim 1, wherein in the step (A), the ruthenium layer of the first substrate is a ruthenium layer doped with boron, aluminum, gallium, phosphorus or arsenic. The method of claim 1, wherein in the step (A), the germanium epitaxial layer is Si _1-X Ge _X , wherein 0 < X < 1. The method of claim 1, wherein in the step (A), the bismuth epitaxial layer has a thickness of 50 nm to 200 nm. The method of claim 1, wherein in the step (A), at least one surface of the second substrate is further laminated with at least one layer selected from the group consisting of a hafnium oxide layer or a tantalum nitride layer. And the yttrium oxide layer or the tantalum nitride layer is in direct contact with the bismuth epitaxial layer. The method of claim 1, wherein in the step (B), the electrochemical reaction is anodization. The method of claim 1, wherein in the step (B), the porous germanium layer has a pore diameter of between 10 nm and 1000 nm. The method of claim 1, wherein in the step (C), the porous tantalum layer is removed using an alkaline etching solution. The method of claim 12, wherein in the step (C), the alkaline etching solution is at least one selected from the group consisting of tetramethylammonium hydroxide, sodium hydroxide, and potassium hydroxide. . The method of claim 1, further comprising the step (D) of oxidizing the bismuth epitaxial layer to form an oxide layer on the bismuth epitaxial layer. The method of claim 14, wherein after the step (D), the bismuth epitaxial layer has a thickness of 20 nm to 200 nm.