Silicon wafer edge removing method

Abstract

The invention relates to the technical field of silicon wafer edge removing equipment, in particular to a silicon wafer edge removing method which comprises the following steps: S1, taking out a silicon wafer, and growing an oxide layer on the surface of the silicon wafer through a CVD (Chemical Vapor Deposition) method; s2, sucking the silicon wafer by using a sucking disc, and sealing the circumference of the side edge of the silicon wafer by a circle through a cylindrical ring; s3, the front face of the silicon wafer is soaked in a weak oxyhydrogen fluorine acid solution, the lower portion of the silicon wafer is soaked in the weak oxyhydrogen fluorine acid solution, and oxide layers of the front face plane and the front face chamfer of the silicon wafer are removed; and S4, taking out the silicon wafer from the weak oxyhydrogen fluorine acid solution through a manipulator, and releasing the vacuum adsorption of the sucker. According to the silicon wafer edge removing method, the separation of the upper surface and the lower surface of the silicon wafer is realized through the cylindrical ring, so that the back chamfer surface and the front chamfer surface are isolated from each other, and the oxide layers at the back chamfer and the back plane are reserved during oxidation removal, so that the problem that the oxide layer protection of the back chamfer surface of the silicon wafer cannot be realized by the existing edge removing technology can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer edge removal equipment, and in particular to a silicon wafer edge removal method. Background Art

[0002] In the field of integrated circuit manufacturing, different types of silicon wafers are manufactured according to different uses. The processing of single crystal silicon wafers generally includes crystal pulling, slicing, grinding, polishing, and cleaning. For epitaxial wafers, an additional epitaxial process is required after the cleaning process. During the epitaxial growth process of doped silicon wafers, attention must be paid to the self-doping phenomenon. The heavily doped components will evaporate into the reaction chamber at high temperatures and participate in the epitaxial reaction, which will seriously affect the quality of the epitaxial layer, such as resistivity. When heavily doped silicon wafers are used as substrates for epitaxial wafers, in addition to the above processes, they also need to go through back sealing and edge etching.

[0003] The so-called back sealing treatment refers to the back dopant overflow prevention treatment carried out to prevent the occurrence of the self-doping effect. Usually, a thin film is deposited on the back of the silicon wafer by a vapor deposition method (Chemical Vapour Deposition, CVD). The film can effectively prevent the dopant from diffusing outward, that is, the film prevents the dopant from escaping into the reaction chamber at high temperature like a sealing layer. In the prior art, silicon dioxide (SiO2) or silicon nitride (Si3N4) or polycrystalline silicon is usually used as the basic material for making the back sealing film. However, during the thin film process, the film is not only grown on one side of the silicon wafer, but also on the other side and chamfered surface of the silicon wafer. The SiO2 residue on the chamfered surface and the front of the silicon wafer caused by the back sealing process, and even the SiO2 residue on the back edge of the silicon wafer may become the nucleation center in the epitaxial growth process, forming polycrystalline and amorphous (amorphous silicon) at the edge, thereby affecting the epitaxial quality and reducing the effective area of ​​the epitaxial. The lattice defects at the edge after epitaxy can cause low edge yield of the subsequent device.

[0004] The most widely used edge back-sealing film removal processing technology in industry currently includes manually or automatically attaching a layer of acid-resistant and high-temperature-resistant blue film on the back of the back-sealing film, or using a vacuum suction cup to adsorb the silicon wafer and isolate the silicon dioxide film that does not need to be etched through the suction cup rubber ring.

[0005] However, with the special requirements of epitaxial manufacturers for epitaxial processes, new requirements have been put forward for the back sealing range of heavily doped substrate silicon wafers, and the oxide layer on the back and back chamfer surface should not be removed. In response to this requirement, the two existing edge removal processes of back filming and suction cup adsorption protection cannot achieve the protection of the oxide layer on the back chamfer surface. Summary of the invention

[0006] The purpose of the present invention is to provide a silicon wafer edge removal method to solve the problem that the two existing edge removal processes of back film lamination and suction cup adsorption protection proposed in the above background technology cannot protect the oxide layer of the back chamfer surface.

[0007] To achieve the above object, the present invention provides a method for edge removal of a silicon wafer, comprising the following steps:

[0008] S1, taking out the silicon wafer, and growing an oxide layer on the surface of the silicon wafer by CVD method;

[0009] S2. Use a suction cup to suck the silicon wafer, so that the inner wall of the cylindrical ring contacts the outer wall of the wafer, and the cylindrical ring seals the side circumference of the silicon wafer to separate the front and back sides of the silicon wafer;

[0010] S3, using a manipulator to drive the cylindrical ring, the suction cup and the silicon wafer to move as a whole, immersing the silicon wafer with its front side facing downward in a weak hydrofluoric acid solution, isolating the upper part of the silicon wafer from the weak hydrofluoric acid solution through the cylindrical ring, immersing the lower part of the silicon wafer in the weak hydrofluoric acid solution, and removing the oxide layer on the front plane and the front chamfer of the silicon wafer;

[0011] S4. The silicon wafer is taken out from the weak hydrofluoric acid solution by a robot, the vacuum adsorption of the suction cup is released, and the silicon wafer is separated from the inner wall of the cylindrical ring, thereby forming a back sealing layer on the back plane and back chamfer of the silicon wafer.

[0012] Preferably, the cylindrical ring is an annular structure, and the inner wall is matched with the circumferential outer wall of the silicon wafer. The suction cup is arranged on the back side of the silicon wafer, and a negative pressure tube is installed on the top of the suction cup.

[0013] Preferably, a limit block is installed on the inner wall of the cylindrical ring located on the upper part of the silicon wafer, and the bottom surface of the limit block is provided with an arc surface, the shape of which is compatible with the shape of the chamfered surface on the back side of the silicon wafer.

[0014] Preferably, a groove is provided on the inner wall of the cylindrical ring near the side of the silicon wafer, and a sealing ring is installed inside the groove, and the sealing ring is made of silicone material.

[0015] Preferably, the suction cup is a circular structure, and its size is smaller than that of the silicon wafer.

[0016] Preferably, when the silicon wafer is immersed face down in a weak hydrofluoric acid solution, the highest point of the cylindrical ring is located above the liquid surface of the weak hydrofluoric acid solution.

[0017] Preferably, the outer side of the negative pressure tube is connected to the inner wall of the cylindrical ring through a bracket.

[0018] Preferably, the robot arm can move in three planes, XYZ, thereby driving the silicon wafer to move in three-dimensional space.

[0019] Preferably, when the silicon wafer is immersed downward into the solution to remove the oxide layer, the entire silicon wafer is arranged horizontally and slowly enters downward into the weak hydrofluoric acid solution.

[0020] Preferably, the silicon wafer is repeatedly immersed in the weak hydrofluoric acid solution by moving the silicon wafer up and down multiple times by a robot.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the silicon wafer deburring method, the upper and lower surfaces of the silicon wafer are separated by a cylindrical ring, so that the back chamfered surface and the front chamfered surface are isolated from each other. When removing oxidation, only the lower part of the silicon wafer is immersed in a weak hydrofluoric acid solution to remove the oxide layer on the front plane and the front chamfer of the silicon wafer, while retaining the oxide layer on the back chamfer and the back plane, thereby solving the problem that the existing deburring technology cannot protect the oxide layer on the back chamfered surface of the silicon wafer.

[0023] 2. In the silicon wafer deburring method, the sealing of the contact position between the inner side of the cylindrical ring and the silicon wafer during processing is ensured by a limit block and a sealing ring, so as to prevent the solution from penetrating to the upper part and ensure smooth processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the partial structure inside the present invention.

[0027] The meaning of each number in the figure is:

[0028] 1. Cylindrical ring; 11. Limit block; 111. Arc surface; 12. Groove; 121. Sealing ring; 2. Suction cup; 3. Negative pressure tube; 31. Bracket; 4. Silicon wafer. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a method for edge removal of a silicon wafer, such as Figure 1-Figure 3 As shown, the following steps are included:

[0031] S1, taking out the silicon wafer 4, and growing an oxide layer on the surface of the silicon wafer 4 by a CVD method;

[0032] S2, using the suction cup 2 to suck the silicon wafer 4, the inner wall of the cylindrical ring 1 is in contact with the circumferential outer wall of the wafer 4, and the cylindrical ring 1 is used to seal the side circumference of the silicon wafer 4 to isolate the front and back sides of the silicon wafer 4;

[0033] S3, using a manipulator to drive the cylindrical ring 1, the suction cup 2 and the silicon wafer 4 to move as a whole, immersing the silicon wafer 4 with its front side facing downward in a weak hydrofluoric acid solution, isolating the upper part of the silicon wafer 4 from the weak hydrofluoric acid solution through the cylindrical ring 1, immersing the lower part of the silicon wafer 4 in the weak hydrofluoric acid solution, and removing the oxide layer on the front plane and the front chamfer of the silicon wafer 4;

[0034] S4. The silicon wafer 4 is taken out from the weak hydrofluoric acid solution by a robot, the vacuum adsorption of the suction cup 2 is released, and the silicon wafer 4 is separated from the inner wall of the cylindrical ring 1, thereby forming a back sealing layer on the back plane and the back chamfer of the silicon wafer 4.

[0035] In this embodiment, the cylindrical ring 1 is an annular structure, and the inner wall thereof is matched with the circumferential outer wall of the silicon wafer 4 . The suction cup 2 is arranged on the back side of the silicon wafer 4 , and a negative pressure tube 3 is installed on the top of the suction cup 2 .

[0036] Specifically, a limit block 11 is installed on the inner wall of the cylindrical ring 1 at the upper part of the silicon wafer 4, and the bottom surface of the limit block 11 is provided with an arc surface 111. The shape of the arc surface 111 is adapted to the shape of the chamfered surface on the back of the silicon wafer 4, so that when the silicon wafer 4 is adsorbed, the limit block 11 limits the silicon wafer 4 so that it is always located in a fixed position.

[0037] Furthermore, a groove 12 is provided on the inner wall of the cylindrical ring 1 near the side of the silicon wafer 4, and a sealing ring 121 is installed inside the groove 12. The sealing ring 121 is made of silicone material. The sealing ring 121 is used to seal the contact position between the outer side of the silicon wafer 4 and the inner wall of the cylindrical ring 1, so that the cylindrical ring 1 can smoothly separate the upper and lower sides of the silicon wafer 4, which is convenient for deoxidation operation on the front side of the silicon wafer 4.

[0038] Furthermore, the suction cup 2 is a circular structure, and its size is smaller than that of the silicon wafer 4 , so that the silicon wafer 4 can be smoothly adsorbed by the suction cup 2 .

[0039] Furthermore, when the silicon wafer 4 is immersed in the weak hydrofluoric acid solution with its front side facing downward, the highest point of the cylindrical ring 1 is located above the liquid surface of the weak hydrofluoric acid solution, so as to prevent the weak hydrofluoric acid solution from overflowing from the upper part of the cylindrical ring 1 .

[0040] Furthermore, the outer side of the negative pressure tube 3 is connected to the inner wall of the cylindrical ring 1 through the bracket 31, so as to facilitate the relative fixation of the cylindrical ring 1 and the suction cup 2.

[0041] Furthermore, the manipulator can move on three planes, XYZ, so as to drive the silicon wafer 4 to move in three-dimensional space, so as to smoothly drive the silicon wafer 4 to move randomly and facilitate loading and unloading during immersion.

[0042] Furthermore, when the silicon wafer 4 is immersed in the solution to remove the oxide layer, the entire silicon wafer 4 is arranged horizontally and slowly enters the weak hydrofluoric acid solution to avoid the solution from sputtering outward, ensuring that the front side of the silicon wafer 4 is in uniform contact with the solution to ensure that the oxidation is fully removed.

[0043] Furthermore, the silicon wafer 4 is repeatedly immersed in the weak hydrofluoric acid solution by the manipulator to perform multiple up-and-down movements on the silicon wafer 4, thereby fully removing the oxide layer.

[0044] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for edge removal of a silicon wafer, characterized in that: The steps include: S1, taking out the silicon wafer (4), and growing an oxide layer on the surface of the silicon wafer (4) by a CVD method; S2. Use the suction cup (2) to suck the silicon wafer (4), so that the inner wall of the cylindrical ring (1) contacts the circumferential outer wall of the wafer (4), and the cylindrical ring (1) is used to seal the circumference of the side of the silicon wafer (4) to isolate the front and back sides of the silicon wafer (4); S3, using a manipulator to drive the cylindrical ring (1), the suction cup (2) and the silicon wafer (4) to move as a whole, immersing the silicon wafer (4) with its front side facing downward in a weak hydrofluoric acid solution, isolating the upper part of the silicon wafer (4) from the weak hydrofluoric acid solution through the cylindrical ring (1), immersing the lower part of the silicon wafer (4) in the weak hydrofluoric acid solution, and removing the oxide layer on the front plane and the front chamfer of the silicon wafer (4); S4. The silicon wafer (4) is taken out from the weak hydrofluoric acid solution by a robot, the vacuum adsorption of the suction cup (2) is released, and the silicon wafer (4) is separated from the inner wall of the cylindrical ring (1), thereby forming a back sealing layer on the back plane and the back chamfer of the silicon wafer (4).

2. The method for edge removal of a silicon wafer according to claim 1, characterized in that: The cylindrical ring (1) is an annular structure, and the inner wall thereof is adapted to the circumferential outer wall of the silicon wafer (4); the suction cup (2) is arranged on the back side of the silicon wafer (4), and a negative pressure tube (3) is installed on the top of the suction cup (2).

3. The method for edge removal of a silicon wafer according to claim 1, characterized in that: A limit block (11) is installed on the inner wall of the cylindrical ring (1) at the upper part of the silicon wafer (4), and a curved surface (111) is provided on the bottom surface of the limit block (11), wherein the shape of the curved surface (111) matches the shape of the chamfered surface on the back side of the silicon wafer (4).

4. The method for edge removal of a silicon wafer according to claim 1, characterized in that: A groove (12) is provided on the inner wall of the cylindrical ring (1) near the side of the silicon wafer (4), and a sealing ring (121) is installed inside the groove (12), wherein the sealing ring (121) is made of silicone material.

5. The method for edge removal of a silicon wafer according to claim 1, characterized in that: The suction cup (2) is a circular structure, and its size is smaller than that of the silicon wafer (4).

6. The method for edge removal of a silicon wafer according to claim 1, characterized in that: When the silicon wafer (4) is immersed in a weak hydrofluoric acid solution with its front side facing downward, the highest point of the cylindrical ring (1) is located above the liquid surface of the weak hydrofluoric acid solution.

7. The method for edge removal of a silicon wafer according to claim 2, characterized in that: The outer side of the negative pressure tube (3) is connected to the inner wall of the cylindrical ring (1) via a bracket (31).

8. The method for edge removal of a silicon wafer according to claim 1, characterized in that: The manipulator can move on three planes, XYZ, thereby driving the silicon wafer (4) to move in three-dimensional space.

9. The method for edge removal of a silicon wafer according to claim 1, characterized in that: When the silicon wafer (4) is immersed downward into the solution to remove the oxide layer, the entire silicon wafer (4) is arranged horizontally and slowly enters downward into the weak hydrofluoric acid solution.

10. The method for edge removal of a silicon wafer according to claim 1, characterized in that: The silicon wafer (4) is repeatedly immersed in the weak hydrofluoric acid solution by performing multiple up-and-down movements of the silicon wafer (4) by means of a mechanical arm.

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