Method for producing semiconductor wafer

Abstract

The invention relates to a method for producing a semiconductor wafer, which comprises the following steps of: 1, cutting: manufacturing a silicon ingot, cutting the silicon ingot into a disc-shaped wafer with a certain thickness according to a cutting line, barreling the outer diameter of the silicon ingot before cutting, and grinding a positioning groove which is an arc-shaped groove in the side surface of the silicon ingot; after cutting, the wafer is machined, the machining steps comprise edge rounding, surface layer grinding and chamfering, and chamfers are arc-shaped chamfers; 2, chemical processing including oxidation, photoetching, etching, chemical vapor deposition and ion implantation; 3, testing and packaging: the positioning groove adopts an arc-shaped groove and is in an arc shape, and the edge of the wafer is enabled to be in a circular arc shape by combining the operations of edge rounding and chamfering on the wafer after cutting, so that the uneven thickness of photoresist in a photoetching process is avoided; meanwhile, sediments are prevented from being deposited at the edge in the deposition process; and laser cutting is adopted, so that the defects of damage, uneven thickness, bending and warping of the wafer can be reduced.

Description

Technical Field

[0001] The present invention relates to a method for producing a semiconductor wafer. Background Art

[0002] During the wafer cutting process, the silicon ingot is generally fixed on the workbench of the cutting machine, and then cut into disc-shaped wafers by a blade or wire saw. Since the photolithography machine needs to use the positioning edge to initially position and calibrate the wafer, a plane or V-groove is ground on the silicon ingot before cutting to serve as the positioning edge or positioning groove of the wafer after cutting. The cutting of the blade and wire saw will bring a great impact to the silicon ingot, causing the cut part of the wafer to warp or deform. At the same time, the positioning edge or positioning groove will also cause the wafer to generate internal stress during the cutting and forming process, and the internal stress will be dispersed with subsequent cutting, causing the wafer to break or crack, affecting the cutting effect. At the same time, the cutting ability of the blade will also change with the length of use. Therefore, the cutting conditions of the wafer are not stable enough, which will further affect the wafer cutting effect. In addition, there are tips on the plane or V-groove. In the photolithography process, photoresist is applied by rotation. The centrifugal force of rotation will cause the photoresist to accumulate at the tip edge of the plane or V-groove, causing uneven thickness of the photoresist. At the same time, during the deposition process, the sediments will preferentially accumulate on the right-angled edges, so the sediments will be deposited on the plane or the right-angled edges of the V-groove, affecting the deposition effect. Summary of the invention

[0003] The technical problem to be solved by the present invention is: In order to overcome the above technical problems, the present invention provides a method for producing semiconductor wafers.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a method for producing a semiconductor wafer, comprising the following steps:

[0005] Step 1, cutting: manufacture silicon ingots, cut the silicon ingots into disc-shaped wafers of a certain thickness according to the cutting line. Before cutting, first roll the outer diameter of the silicon ingot, and grind the positioning groove on the side of the silicon ingot. The positioning groove is an arc groove. Since the outer diameter and roundness of the crystal rod have certain deviations during its growth, and its outer cylindrical surface is also uneven, the outer diameter must be trimmed and rolled to obtain the desired size of the wafer. The diameter of the disc-shaped wafer after cutting determines the size of the final wafer. After cutting, the wafer is machined, and the machining steps include rounding, surface grinding and chamfering; wherein the chamfer is an arc chamfer. The outer edge of the wafer just cut is very sharp, and the silicon single crystal is a brittle material. In order to avoid the cracking of the corners and affect the strength of the wafer, destroy the smoothness of the wafer surface and bring contamination particles to the subsequent process, the rounding process generally uses a dedicated computer-controlled equipment to trim the edge shape and outer diameter of the wafer. Grinding the surface of the wafer can reduce saw marks and surface damage on the front and back, while thinning the wafer and helping to release the stress accumulated during the cutting process. The chamfering of the wafer is to round the edge of the wafer, completely eliminating the possibility of damage during the future circuit manufacturing process. After the chamfering process, the edge can be polished, firstly to further remove the particles attached to the wafer and improve the overall cleanliness, and secondly to obtain excellent surface flatness, further reduce damage, which is conducive to the subsequent wafer processing. Finally, the wafer is thoroughly cleaned and air-dried. A major inventive point of the present invention is that the positioning groove adopts an arc groove, which avoids the disadvantages brought by the common tip of the traditional V groove and flat groove. The arc shape of the positioning groove, combined with the round edge and chamfering operation after cutting, makes the edges of the wafer all arc-shaped, avoiding the uneven thickness caused by the accumulation of centrifugal force at the edge when the photoresist is rotated in the photolithography process; at the same time, in the deposition process, the design of the right angle edge is avoided, which can avoid the deposition of sediment at the edge and improve the deposition effect.

[0006] Step 2: Chemical processing: including oxidation, photolithography, etching, chemical vapor deposition and ion implantation;

[0007] Among them, oxidation is the formation of an oxide layer on the surface of the chip; the oxidation process is the formation of a protective film on the surface of the chip to protect the chip from the influence of chemical impurities, avoid leakage current entering the circuit, prevent diffusion during ion implantation, and prevent the chip from slipping during etching.

[0008] Photolithography includes coating photoresist, exposure and development;

[0009] Etching is the process of removing part of the material on the surface of the chip according to the shape and structure required by the electronic component circuit; the etching step can chemically remove a damaged layer on the surface of the chip caused by processing stress after the previous processing steps.

[0010] Chemical vapor deposition is the process of depositing thin film materials on a wafer to generate electronic component circuits. The reaction products produced during chemical vapor deposition condense to form a solid film, and the newly formed film atoms diffuse on the surface of the wafer to eventually form a patterned film. The advantages of chemical vapor deposition are that it can control the wafer structure, use less chemical substances, have a short reaction time, high production efficiency and low reaction temperature.

[0011] Ion implantation is the process of doping the desired material into the surface of the wafer using an ion implantation process;

[0012] Step 3: Test the package.

[0013] Laser cutting is used in step 1. Specifically, a cutting line is designed according to the surface area of ​​the silicon ingot, and the cutting line is projected onto the silicon ingot using a projector. A laser beam is irradiated along the cutting line, and the laser beam is focused inside the silicon ingot to induce a crack, so that the silicon ingot breaks along the crack, thereby separating the disc-shaped wafers. Laser cutting helps reduce damage to the wafer, uneven thickness, bending and warping defects.

[0014] Step 1 uses an infrared picosecond laser for laser cutting. The pulse width of the infrared picosecond laser is short, usually at the picosecond level, which helps to reduce thermal damage to the wafer, has a small heat-affected zone, can reduce the bending and warping of the wafer caused by thermal deformation, and reduce cutting errors.

[0015] The silicon ingot is a semiconductor single crystal silicon ingot formed by recrystallization of a crystal rod of a polycrystalline semiconductor material.

[0016] In the photolithography step, photoresist is coated: a layer of photoresist is applied on the surface of the wafer, and a mask is placed on the photoresist; exposure: the pattern on the mask is exposed to the photoresist on the surface of the wafer through a light source and a lens system; development: the exposed or unexposed areas are then selectively removed by spraying a developer on the wafer, leaving the desired electronic component circuit pattern on the wafer surface.

[0017] The material required in the ion implantation process is boron or phosphorus.

[0018] The ion implantation process also includes an annealing step. The annealing step is a high-temperature treatment step after the wafer has been ion implanted. The main purpose of this process is to activate the ion implanted dopants and repair any structural damage that may have been caused during the implantation process. Annealing helps to restore the integrity of the wafer and lay the foundation for subsequent manufacturing steps.

[0019] The beneficial effect of the present invention is that in a method for producing semiconductor wafers of the present invention, an arc-shaped groove is used for positioning grooves, thereby avoiding the disadvantages brought by the tips common to traditional V-grooves and flat grooves. The arc-shaped shape of the positioning groove, combined with the operation of chamfering the wafer after cutting, makes the edges of the wafer all arc-shaped, thereby avoiding uneven thickness caused by the accumulation of centrifugal force at the edges when the photoresist is spin-coated in the photolithography process; at the same time, in the deposition process, the design of right-angled edges is avoided, thereby avoiding the deposition of sediments at the edges and improving the deposition effect; the use of laser cutting helps to reduce damage to the wafer, uneven thickness, bending and warping defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 It is a schematic flow chart of the method for producing semiconductor wafers of the present invention. DETAILED DESCRIPTION

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0023] A method for producing a semiconductor wafer of the present invention comprises the following steps:

[0024] Step 1, cutting: manufacturing silicon ingots, cutting the silicon ingots into disc-shaped wafers of a certain thickness according to the cutting line. Before cutting, the outer diameter of the silicon ingot is first rolled and the positioning groove is ground on the side of the silicon ingot, and the positioning groove is an arc groove; after cutting, the wafer is mechanically processed, and the mechanical processing steps include rounding, surface grinding and chamfering; wherein the chamfer is an arc chamfer. Since the outer diameter and roundness of the crystal rod have certain deviations during its growth process, and its outer cylindrical surface is also uneven, the outer diameter must be trimmed and rolled to obtain the desired size of the wafer. The diameter of the disc-shaped wafer after cutting determines the size of the final wafer. The outer edge of the wafer just cut is very sharp, and the silicon single crystal is a brittle material. In order to avoid the cracking of the corners and affect the strength of the wafer, destroy the smoothness of the wafer surface and bring contamination particles to the subsequent process, the rounding process generally uses a dedicated computer-controlled equipment to trim the edge shape and outer diameter of the wafer. Grinding the surface of the wafer can reduce saw marks and surface damage on the front and back, while thinning the wafer and helping to release the stress accumulated during the cutting process. The chamfering of the wafer is to round the edge of the wafer, completely eliminating the possibility of damage during the future circuit manufacturing process. After the chamfering process, the edge can be polished, firstly to further remove the particles attached to the wafer and improve the overall cleanliness, and secondly to obtain excellent surface flatness, further reduce damage, which is conducive to the subsequent wafer processing. Finally, the wafer is thoroughly cleaned and air-dried. A major inventive point of the present invention is that the positioning groove adopts an arc groove, which avoids the disadvantages brought by the common tip of the traditional V groove and flat groove. The arc shape of the positioning groove, combined with the round edge and chamfering operation after cutting, makes the edges of the wafer all arc-shaped, avoiding the uneven thickness caused by the accumulation of centrifugal force at the edge when the photoresist is rotated in the photolithography process; at the same time, in the deposition process, the design of the right angle edge is avoided, which can avoid the deposition of sediment at the edge and improve the deposition effect.

[0025] Step 2: Chemical processing: including oxidation, photolithography, etching, chemical vapor deposition and ion implantation;

[0026] Among them, oxidation is the formation of an oxide layer on the surface of the wafer. The oxidation process forms a protective film on the surface of the wafer to protect the wafer from chemical interference, prevent leakage current from entering the circuit, prevent diffusion during ion implantation, and prevent the wafer from slipping during etching.

[0027] Photolithography includes coating photoresist, exposure and development;

[0028] Etching is the process of removing part of the material on the surface of the chip according to the shape and structure required by the electronic component circuit. The etching step can chemically remove a layer of damage on the surface of the chip caused by processing stress after the previous processing steps.

[0029] Chemical vapor deposition is the process of depositing thin film materials on a wafer to generate electronic component circuits. The reaction products produced during chemical vapor deposition condense to form a solid film, and the newly formed film atoms diffuse on the surface of the wafer to eventually form a patterned film. The advantages of chemical vapor deposition are that the wafer structure can be controlled, less chemical substances are used, the reaction time is short, the production efficiency is high, and the reaction temperature is low.

[0030] Ion implantation is the process of doping the desired material into the surface of the chip using an ion implantation process.

[0031] Step 3: Test the package.

[0032] Laser cutting is used in step 1. Specifically, a cutting line is designed according to the surface area of ​​the silicon ingot, and the cutting line is projected onto the silicon ingot using a projector. A laser beam is irradiated along the cutting line, and the laser beam is focused inside the silicon ingot to induce a crack, so that the silicon ingot breaks along the crack, thereby separating the disc-shaped wafers. Laser cutting helps reduce damage to the wafer, uneven thickness, bending and warping defects.

[0033] Step 1 uses an infrared picosecond laser for laser cutting. The pulse width of the infrared picosecond laser is short, usually at the picosecond level, which helps to reduce thermal damage to the wafer, has a small heat-affected zone, can reduce the bending and warping of the wafer caused by thermal deformation, and reduce cutting errors.

[0034] The silicon ingot is a semiconductor single crystal silicon ingot formed by recrystallization of a crystal rod of a polycrystalline semiconductor material.

[0035] In the photolithography step, photoresist is coated: a layer of photoresist is applied on the surface of the wafer, and a mask is placed on the photoresist; exposure: the pattern on the mask is exposed to the photoresist on the surface of the wafer through a light source and a lens system; development: the exposed or unexposed areas are then selectively removed by spraying a developer on the wafer, leaving the desired electronic component circuit pattern on the wafer surface.

[0036] The material required in the ion implantation process is boron or phosphorus to change the electrical properties of a certain part of the wafer.

[0037] The ion implantation process also includes an annealing step. The annealing step is a high-temperature treatment step after the wafer has been ion implanted. The main purpose of this process is to activate the ion implanted dopants and repair any structural damage that may have been caused during the implantation process. Annealing helps to restore the integrity of the wafer and lay the foundation for subsequent manufacturing steps.

[0038] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for producing a semiconductor wafer, characterized in that: The following steps are involved: Step 1, cutting: manufacturing a silicon ingot, grinding a positioning groove on the side of the silicon ingot, wherein the positioning groove is an arc-shaped groove, and cutting the silicon ingot into a disc-shaped wafer of a certain thickness according to the cutting line. Before cutting, the outer diameter of the silicon ingot is firstly rolled, and after cutting, the wafer is mechanically processed, and the mechanical processing steps include rounding, surface grinding and chamfering; wherein the chamfer is an arc-shaped chamfer; Step 2: Chemical processing: including oxidation, photolithography, etching, chemical vapor deposition and ion implantation; Among them, oxidation is the formation of an oxide layer on the surface of the wafer; Photolithography includes coating photoresist, exposure and development; Etching is the process of removing part of the material on the wafer surface according to the shape and structure required by the electronic component circuit; Chemical vapor deposition is the process of depositing thin film materials on a wafer to generate electronic component circuits. The reaction products produced during chemical vapor deposition condense to form a solid film, and the newly formed film atoms diffuse on the wafer surface to eventually form a patterned film. Ion implantation is the process of doping the desired material into the surface of the wafer using an ion implantation process; Step 3: Test the package.

2. The method for producing a semiconductor wafer according to claim 1, wherein: Laser cutting is used in step 1. Specifically, a cutting line is designed according to the surface area of ​​the silicon ingot, and the cutting line is projected onto the silicon ingot using a projector. A laser beam is irradiated along the cutting line, and the laser beam is focused inside the silicon ingot to induce a crack, so that the silicon ingot breaks along the crack, thereby dividing the disc-shaped wafers.

3. The method for producing a semiconductor wafer according to claim 2, wherein: Step 1: Laser cutting using an infrared picosecond laser.

4. The method for producing a semiconductor wafer according to claim 1, wherein: The silicon ingot is a semiconductor single crystal silicon ingot formed by recrystallization of a crystal rod of a polycrystalline semiconductor material.

5. The method for producing a semiconductor wafer according to claim 1, wherein: In the photolithography step, photoresist is applied: a layer of photoresist is applied on the surface of the wafer and a mask is placed on the photoresist; Exposure: The pattern on the mask is exposed to the photoresist on the wafer surface through the light source and lens system; Development: The exposed or unexposed areas are then selectively removed by spraying a developer on the wafer, leaving the desired electronic component circuit pattern on the wafer surface.

6. The method for producing a semiconductor wafer according to claim 1, wherein: The material required in the ion implantation process is boron or phosphorus.

7. The method for producing a semiconductor wafer according to claim 1, wherein: The ion implantation process also includes an annealing step.

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