Processing method of semiconductor substrate

Abstract

To provide a processing method of a semiconductor substrate.SOLUTION: A semiconductor substrate processing method includes material processing including providing a raw substrate having opposing raw and bonded sides, providing a hole providing substrate, and bonding the hole providing substrate to the bonded side of the raw substrate via a wafer bonding process to obtain a substrate pair. The semiconductor substrate processing method can provide high speed electrochemical etching.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a substrate processing method, and more particularly to a semiconductor substrate processing method. [Background technology]

[0002] The main carrier of a normal N-type semiconductor substrate is the electron. In order to cause an electrochemical reaction with the electrolyte, it is necessary to transfer the electrons by irradiating strong light, applying a transverse electric field, applying the Hall effect, etc., and expose the holes at the interface between the N-type semiconductor substrate and the electrolyte, and then carry out the electrochemical etching process. Summary of the Invention [Problem to be solved by the invention]

[0003] However, these methods are subject to environmental variables such as distance and intensity that affect the reliability of etching, so the current industrial technology trend is to develop electrochemical etching techniques that do not use a light source but are deflected by an electromagnetic field.

[0004] The present invention provides a method for processing a semiconductor substrate to achieve high speed electrochemical etching. [Means for solving the problem]

[0005] The present invention provides a method for processing a semiconductor substrate, which includes performing material processing to provide an unprocessed substrate having opposing unprocessed and bonded sides, providing a hole supplying substrate, and bonding the hole supplying substrate to the bonded side of the unprocessed substrate through a wafer bonding process to obtain a substrate pair.

[0006] In one embodiment of the present invention, the untreated substrate is an N-type semiconductor substrate, and the hole supply substrate is a P-type semiconductor substrate.

[0007] In one embodiment of the present invention, the untreated substrate is an intrinsic semiconductor substrate, and the hole supply substrate is a P-type semiconductor substrate.

[0008] In one embodiment of the present invention, the untreated substrate is a lightly doped P-type semiconductor substrate, and the hole supplying substrate is a heavily doped P-type semiconductor substrate.

[0009] In one embodiment of the present invention, the wafer bonding process bonds a hole supply substrate to an untreated substrate.

[0010] In one embodiment of the present invention, the material process includes placing the substrate pair in an electrolyte and performing an electrochemical process, the untreated side having a solid-liquid contact surface in contact with the electrolyte, and the hole supply substrate providing holes to the solid-liquid contact surface to complete the anodization reaction and form a reaction layer on the untreated side.

[0011] In one embodiment of the present invention, the method further comprises separating the hole supplying substrate from the substrate pair after forming the reaction layer.

[0012] In one embodiment of the present invention, after forming the reaction layer, the reaction layer is removed.

[0013] In one embodiment of the present invention, the electrolyte comprises hydrofluoric acid.

[0014] In one embodiment of the present invention, in the material process, the semiconductor substrate processing apparatus is suitable for performing an electrochemical process on a pair of substrates, and includes an electrolytic cell, a positive electrode plate, and a negative electrode plate. The electrolytic cell is filled with an electrolyte. The positive electrode plate and the negative electrode plate are respectively installed on opposite sides of the inside of the electrolytic cell. The pair of substrates is installed in the electrolyte and is located between the positive electrode plate and the negative electrode plate. The untreated substrate faces the negative electrode plate, and the hole supplying substrate faces the positive electrode plate, and the pair of substrates performs an electrochemical process in the electrolyte, the untreated substrate has a solid-liquid contact surface in contact with the electrolyte, and the hole supplying substrate provides holes to the solid-liquid contact surface to perform an anodization reaction.

[0015] In one embodiment of the present invention, the electrolytic cell includes a cell body, a base and a cover, the base and the cover are respectively installed on the bottom and top of the cell body, and the cover is installed at the electrolyte inlet and outlet and the gas inlet and outlet.

[0016] In one embodiment of the present invention, the semiconductor substrate processing apparatus further includes two gaskets, and a positioning groove suitable for clamping the peripheral edges of the substrate pair is provided on the inner wall of the electrolytic cell, one of the two gaskets is installed between the peripheral edge of the substrate pair facing the positive electrode plate and the positioning groove, and the other of the two gaskets is installed between the peripheral edge of the substrate pair facing the negative electrode plate and the positioning groove.

[0017] The present invention uses direct wafer bonding technology to build a temporary PN junction structure, which allows for fast material processing (e.g., electrochemical etching) and is less prone to introducing impurities that cause unwanted chemical contamination. After material processing, the bonded substrate pair can be easily separated to remove the hole supply substrate, which serves as the intermediate electrode, and can be reused after being removed.

[0018] In order to make the above and other objects, features and advantages of the present invention more clearly comprehensible, the following detailed description is given with reference to the accompanying drawings in which: [Brief description of the drawings]

[0019] 1A to 1E are a flowchart of a semiconductor substrate processing method according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a material process according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing an application of a semiconductor substrate processing apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1A to 1E are flow charts of a method for processing a semiconductor substrate according to an embodiment of the present invention. As shown in FIG. 1A, an unprocessed substrate 10 and a hole supplying substrate 12 are provided, the unprocessed substrate 10 has an unprocessed side 101 and a bonding side 102 facing each other, and the size of the hole supplying substrate 12 is the same as or close to the size of the unprocessed substrate 10. Then, as shown in FIG. 1B, the hole supplying substrate 12 is bonded to the bonding side 102 (FIG. 1) of the unprocessed substrate 10 by a wafer bonding process to obtain a substrate pair 14. Then, as shown in FIG. 1C, a material process is performed on the substrate pair 14 to form a reaction layer 16 on the unprocessed side 101 (FIG. 1).

[0021] In one embodiment, after the reaction layer 16 is formed, the hole supplying substrate 12 is separated from the substrate pair 14, as shown in Figure ID. In one embodiment, the reaction layer 16 can be further removed to obtain a thinned substrate 10', as shown in Figure ID.

[0022] In one embodiment, the untreated substrate 10 and the hole supplying substrate 12 can be subjected to a cleaning process and a polishing process before the wafer bonding process, and the cleaning process can be, for example, an RCA cleaning step. Also, the wafer bonding process can be, for example, a hydrophobic bond, and the bond between the hole supplying substrate 12 and the untreated substrate 10 is a van der Waals bond, without annealing, and the bond energy is 120 mJ / m 2 to facilitate separation of the untreated substrate 10 and the hole supplying substrate 12 after material processing.

[0023] FIG. 2 is a schematic diagram of a material process according to an embodiment of the present invention. As shown in FIG. 2, the material process is performed by placing a substrate pair 14 in an electrolyte 18 to carry out an electrochemical process, and the untreated side 101 of the untreated substrate 10 has a solid-liquid contact surface 101a in contact with the electrolyte 18, and the hole supply substrate 12 provides holes 20 to the solid-liquid contact surface 101a to complete the anodization reaction and form a reaction layer 16 on the untreated side 101. Specifically, in one embodiment, when the untreated substrate 10 is an N-type semiconductor substrate or the like and the hole supply substrate 12 is a P-type semiconductor substrate or the like, the untreated substrate 10 (N-type semiconductor substrate) and the hole supply substrate 12 (P-type semiconductor substrate) are bonded together by a wafer bonding process to form a PN junction 22. Due to the characteristics of the interface barrier of the PN junction 22, the role of the holes 20 in the untreated substrate 10 (N-type semiconductor substrate) becomes a primary current from a secondary carrier. Therefore, under the driving of the electric field E, the holes 20 can reach the solid-liquid contact surface 101a and cause an anodic oxidation reaction, which significantly improves the anodic oxidation efficiency of the untreated side 101.

[0024] In one embodiment, the reaction layer 16 formed on the untreated side 101 by the anodization reaction is a weakened layer having a plurality of holes, and this weakened layer exhibiting a sponge-like hollow structure has a material strength lower than that of the other solid parts of the untreated substrate 10. Therefore, it can be easily removed in a subsequent process to achieve the effect of thinning the untreated substrate 10.

[0025] Following the above description, in the material process, the semiconductor substrate processing apparatus according to the embodiment of the present invention is used to perform an electrochemical process on a pair of substrates 14. FIG. 3 is a schematic diagram showing the application of the semiconductor substrate processing apparatus according to the embodiment of the present invention. The semiconductor substrate processing apparatus 30 includes an electrolytic cell 32, a positive electrode plate 34, and a negative electrode plate 36. In one embodiment, the electrolytic cell 32 includes a cell body 321, a base 322, and a lid 323, the base 322 and the lid 323 are respectively installed on the bottom and top of the cell body 321, and the lid 323 is installed at an inlet / outlet 324 for the electrolyte and an inlet / outlet 325 for the gas. The electrolytic cell 32 is filled with an electrolyte 18, which includes, for example, hydrofluoric acid (HF) or hydrofluoric acid and ethanol (C2H5OH), and the hydrofluoric acid and ethanol are mixed in a ratio of 1:1. The positive electrode plate 34 and the negative electrode plate 36 are respectively installed on opposite sides inside the electrolytic cell 32. In one embodiment, the positive electrode plate 34 and the negative electrode plate 36 are made of platinum and are further electrically connected to a power supply system 38 that provides the necessary current or voltage.

[0026] When performing the electrochemical process, the substrate pair 14 is placed in the electrolyte 18 and positioned between the positive electrode plate 34 and the negative electrode plate 36. The untreated substrate 10 faces the negative electrode plate 36, and the hole supplying substrate 12 faces the positive electrode plate 34. In the embodiment shown in FIG. 3, an example of performing the anodization process on two substrate pairs 14 at the same time is described, but is not limited to this. In the anodization process, the holes 20 (FIG. 2) provided by the hole supplying substrate 12 under the driving of the electric field E reach the solid-liquid contact surface 101a of the untreated substrate 10 to cause the anodization reaction. In one embodiment, in the anodization process, the flow rate of the electrolyte 18 is adjusted to obtain a suitable etching rate, and the electrolyte inlet / outlet 324 and the gas inlet / outlet 325 are provided to circulate in combination with a pump (not shown), thereby keeping the electrolyte 18 fresh and eliminating the hydrogen gas bubbles generated during the reaction process.

[0027] Following the above description, in one embodiment, as shown in FIG. 3, the semiconductor substrate processing apparatus 30 further includes a plurality of gaskets 40, 40', and the inner wall of the electrolytic bath 32 is provided with a positioning groove 326, which is suitable for holding the periphery of the substrate pair 14. In one embodiment, the positioning groove 326 is provided on the inner wall opposite to the base 322 and the lid 323, respectively, and two gaskets 40, 40' are assigned to each substrate pair 14. One gasket 40 of the two gaskets is provided between the periphery of the substrate pair 14 facing the positive electrode plate 34 and the inner wall of the positioning groove 326, and the other gasket 40' of the two gaskets is provided between the periphery of the substrate pair 14 facing the negative electrode plate 36 and the inner wall of the positioning groove 326. The provision of the gaskets 40, 40' can prevent the electrolyte 18 on both sides of the substrate pair 14 from leaking out of the positioning groove 326 and mixing.

[0028] As described above, in the semiconductor substrate processing method according to the embodiment of the present invention, when the unprocessed substrate is an N-type semiconductor substrate and the hole supply substrate is a P-type semiconductor substrate, the P-type semiconductor substrate is bonded to the rear surface of the N-type semiconductor substrate as an intermediate electrode by a wafer bonding process to form a removable PN junction. This PN junction converts the role of holes in the N-type semiconductor substrate from secondary carriers to primary current carriers, thereby greatly improving the anodization efficiency of the N-type semiconductor substrate surface. After the electrochemical etching process is completed, the P-type semiconductor substrate as the intermediate electrode can be easily separated from the N-type semiconductor substrate, and the processed N-type semiconductor substrate remains pure without the risk of contamination, and the separated P-type semiconductor substrate can also be reused.

[0029] On the other hand, the untreated substrate is not necessarily an N-type semiconductor substrate. In one embodiment, the untreated substrate is a lightly doped P-type semiconductor substrate, and the hole supply substrate is a heavily doped P-type semiconductor substrate.

[0030] In one embodiment, the untreated substrate is an intrinsic semiconductor substrate, such as a high-resistance silicon wafer. The high-resistance silicon wafer can be applied to the manufacture of devices such as high voltage and high power, which is an important industrial material applied in national defense science and technology. In addition, the high-resistance silicon wafer is difficult to perform anodization because it is deflected to P type or N type, and it is very difficult to detect the electric field and separate the holes. In the method for treating a semiconductor substrate according to the embodiment of the present invention, a highly doped P type semiconductor substrate, such as highly doped P type silicon, is used as a hole supply substrate, and the high-resistance silicon wafer and the highly doped P type silicon are bonded together by a wafer bonding process. In this way, the highly doped P type silicon is used as an intermediate electrode to manufacture a PN junction, and the energy of the highly doped P type silicon is deflected to the valence band, which is much lower than that of the high-resistance silicon wafer material, so that it can efficiently transport holes under bias, and the holes can be transported to the solid-liquid contact surface of the high-resistance silicon wafer by moving between lattices to generate an anodization reaction.

[0031] In one embodiment, the unprocessed substrate is a silicon carbide single crystal substrate. The semiconductor substrate processing method according to the embodiment of the present invention can obtain perfect graphene nanoparticles by anodizing and electrolyzing the silicon carbide single crystal substrate. Due to the advantage of low cost, the semiconductor substrate processing method according to the embodiment of the present invention is expected to enable a large amount of graphene particles produced from the silicon carbide single crystal substrate to be applied in a wide range of military and industrial applications.

[0032] In one embodiment, the untreated substrate is a gallium nitride substrate. The method for treating a semiconductor substrate according to the embodiment of the present invention can be used to anodize the gallium nitride substrate to produce porous gallium nitride. This type of material can be used to fabricate high density energy storage devices, powerful photocatalytic converters, sensitive ultraviolet light sensors, etc.

[0033] From the above, the semiconductor substrate processing method according to the embodiment of the present invention uses a direct wafer bonding technique to build a temporary PN junction structure, which allows for faster installation than methods such as epitaxial growth, diffusion, or ion implantation, realizes fast electrochemical etching (e.g., anodization), and is less likely to introduce impurities that cause unwanted chemical contamination. After anodization, the bonded substrate pair can be easily separated to remove the hole supply substrate that serves as the intermediate electrode, and this hole supply substrate can be reused even after it is removed. In addition, even when a high-resistivity (high-purity) silicon wafer is biased to P-type or N-type, the PN junction structure can efficiently transport holes to the solid-liquid contact surface to complete the anodization reaction. In addition, based on the Fermi energy consistency principle in thermodynamic equilibrium, the semiconductor substrate processing method according to the embodiment of the present invention can meet the anodization requirements of many N-type and high-resistivity semiconductor substrates while consuming efficient and low energy, and can even fabricate new nanostructures.

[0034] The present invention has been disclosed above using examples, but the present invention is not limited thereto. Those skilled in the art can make some modifications without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims. [Explanation of symbols]

[0035] 10: Untreated substrate 10': Thinned substrate 101: Untreated side 101a: Solid-liquid contact surface 102:Joining side 12: Hole supply substrate 14: Board pair 16: Reaction layer 18: Electrolyte 20: Hole 22:PN junction E: Electric field 30: Semiconductor substrate processing equipment 32: Electrolytic cell 321: Tank body 322: Base stand 323: Lid 324: Electrolyte inlet / outlet 325: Gas inlet / outlet 326: Positioning groove 34: Positive electrode plate 36: Negative electrode plate 38: Power supply system 40, 40': Gasket

Claims

1. providing an untreated substrate having opposing untreated and bonding sides; providing a hole supplying substrate; A method for processing a semiconductor substrate, comprising: performing a material process to bond the hole source substrate to the bonding side of the unprocessed substrate through a wafer bonding process to obtain a substrate pair.

2. 2. The method for processing a semiconductor substrate according to claim 1, wherein the unprocessed substrate is an N-type semiconductor substrate, and the hole supplying substrate is a P-type semiconductor substrate.

3. 2. The method for processing a semiconductor substrate according to claim 1, wherein the unprocessed substrate is an intrinsic semiconductor substrate, and the hole supplying substrate is a P-type semiconductor substrate.

4. 2. The method of claim 1, wherein the unprocessed substrate is a lightly doped P-type semiconductor substrate, and the hole supplying substrate is a heavily doped P-type semiconductor substrate.

5. 2. The method for processing a semiconductor substrate according to claim 1, further comprising bonding the hole supply substrate to the unprocessed substrate by the wafer bonding process.

6. 2. The method for processing a semiconductor substrate according to claim 1, wherein the material process includes placing the substrate pair in an electrolyte, performing an electrochemical process, the untreated side having a solid-liquid contact surface in contact with the electrolyte, and the hole supplying substrate providing holes to the solid-liquid contact surface to complete an anodization reaction and form a reaction layer on the untreated side.

7. 7. The method of claim 6, further comprising separating the hole supplying substrate from the substrate pair after forming the reaction layer.

8. The method of claim 6 , further comprising removing the reaction layer after the reaction layer is formed.

9. 7. The method for treating a semiconductor substrate according to claim 6, wherein the electrolyte contains hydrofluoric acid.

10. In the material process, a semiconductor substrate processing apparatus is suitable for performing an electrochemical process on the substrate pair, and the semiconductor substrate processing apparatus includes: An electrolytic cell filled with an electrolyte; 2. The method for treating a semiconductor substrate according to claim 1, further comprising: a positive electrode plate and a negative electrode plate, respectively, which are installed on opposite sides inside the electrolytic cell; the substrate pair is suitable for being installed in the electrolyte and is located between the positive electrode plate and the negative electrode plate, the untreated substrate faces the negative electrode plate, the hole supply substrate faces the positive electrode plate, the substrate pair performs the electrochemical process in the electrolyte, the untreated substrate has a solid-liquid contact surface in contact with the electrolyte, and the hole supply substrate provides holes to the solid-liquid contact surface to perform an anodization reaction.

11. The method for treating a semiconductor substrate according to claim 10, characterized in that the electrolytic bath comprises a bath body, a base, and a lid, the base and the lid being respectively installed on the bottom and top of the bath body, and the lid being installed at an inlet / outlet for an electrolyte and an inlet / outlet for a gas.

12. The semiconductor substrate processing method of claim 10, characterized in that the semiconductor substrate processing apparatus further includes two gaskets, the inner wall of the electrolytic cell is provided with a positioning groove suitable for clamping the periphery of the substrate pair, one of the two gaskets is installed between the periphery of the substrate pair facing the positive electrode plate and the positioning groove, and the other of the two gaskets is installed between the periphery of the substrate pair facing the negative electrode plate and the positioning groove.

Images