TWI616936B - Method of epitaxy wafer defect reduction - Google Patents

Abstract

The invention proposes a method for reducing defects in an epitaxial wafer. First, an immersive defect removal process is performed on the original epitaxial wafer to remove many scratches and defects on the original epitaxial wafer. Then, a polishing process is performed. The surface morphology data of the original epitaxial wafer is collected through analysis, and the morphological data is analyzed to obtain the amount of etching to be performed in different regions of the original epitaxial wafer. The process parameters required for different regions are determined by the amount of etching. Targeted etching removes the amount of to-be-etched in different regions of the original epitaxial wafer, thereby removing defects and scratches on the surface of the original epitaxial wafer, forming an epitaxial wafer with a smooth surface, and further improving the performance of the subsequent epitaxial layer. improve.

Description

Formation method for reducing epitaxial wafer defects

The invention relates to the field of semiconductor element manufacturing, and in particular, to a method for forming defects in an epitaxial wafer.

In the conventional epitaxial wafer formation method, the single crystal silicon ingot grown at the distal end and the proximal end is cut to form a block, and then the block is peripherally polished, and a positioning edge or a positioning V groove is formed for It plays the role of position indication; then, the block is sliced to obtain an epitaxial wafer; then, the epitaxial wafer is chamfered; then, double-sided polishing is performed; then, single-sided polishing is performed; , Performing a double-side polishing process; then, performing a single-side polishing process; and finally forming a desired epitaxial layer on the formed epitaxial wafer.

However, the conventional method for forming epitaxial wafers has the following problems: During mechanical processing, such as slicing, grinding, etc., the machine will inevitably cause scratches on the surface of the epitaxial wafer, and the scratches and defects will become The starting point will cause crystal defects such as misalignment and stacking defects in the subsequent formation of the epitaxial layer. When the damage to the epitaxial wafer caused by machining is large, slippage will also occur in the subsequent formation of the epitaxial layer, resulting in The performance of the formed epitaxial layer is greatly reduced.

The object of the present invention is to provide a method for forming defects in an epitaxial wafer, to make the surface of the formed epitaxial wafer smooth without scratches and defects, and to improve the subsequent formation of the epitaxial layer. performance.

In order to achieve the above object, the present invention provides a method for forming defects in an epitaxial wafer, which includes the steps of: providing an original epitaxial wafer; performing an immersive defect removal process on the initial epitaxial wafer; Crystal wafers are polished; the surface morphology of the original epitaxial wafer is detected, and the morphological data are saved; the morphological data is analyzed to obtain the amount to be etched in different regions of the original epitaxial wafer, and The process parameters required for different regions are determined according to the amount to be etched; the different regions of the original epitaxial wafer are etched according to the required process parameters of different regions, so that the surface of the original epitaxial wafer is smoother; The epitaxial wafer is polished on one side to obtain the final epitaxial wafer.

Further, in the method for reducing defects in the epitaxial wafer, a single-piece spin-jet wet method is used to etch different regions of the original epitaxial wafer.

Further, in the method for reducing defects in an epitaxial wafer, the process parameters include a process temperature and a process time.

Further, in the method for reducing defects in an epitaxial wafer, the process temperatures of different regions of the original epitaxial wafer are adjusted by using a chuck partition control resistance heating method.

Further, in the method for reducing defects in an epitaxial wafer, the chuck includes a plurality of micro heating units arranged in a matrix.

Further, in the method for reducing defects in an epitaxial wafer, the method The miniature heating unit is a Peltier effect device or a resistance heating device.

Further, in the method for reducing defects in epitaxial wafers, the micro heating unit is a polyimide heater, a silicone rubber heater, a mica heater, a metal heater, a ceramic heater, or a semiconductor heater. Heater or carbon heater.

Further, in the method for reducing defects in an epitaxial wafer, the micro heating unit is formed by a wire-wound type, a formed foil type, or an imprint type.

Further, in the method for reducing defects in an epitaxial wafer, the power range of a single micro heating unit is 0-20W.

Further, in the method for reducing defects in an epitaxial wafer, the process time is controlled by a single wafer rotation.

Further, in the method for reducing defects in an epitaxial wafer, the single-chip rotary spray wet method sprays an etching solution through a nozzle.

Further, in the method for reducing defects in an epitaxial wafer, the etching solution includes hydrofluoric acid, nitric acid, phosphoric acid, and water, wherein HF: HNO ₃ : H ₃ PO ₄ : H ₂ O mass ratio It was 7%: 30%: 35%: 38%.

Further, in the method for reducing defects in epitaxial wafers, the etching solution used in the immersion defect removal process includes hydrofluoric acid, nitric acid, phosphoric acid, and water, wherein HF: HNO ₃ : H ₃ PO _4: H ₂ O mass ratio of 7%: 30%: 35%: 38%.

Further, in the method for reducing defects in an epitaxial wafer, the step of forming the original epitaxial wafer includes: providing a single crystal silicon ingot; and grinding and rounding the single crystal silicon ingot; Forming positioning edges or positioning V grooves on the single crystal silicon ingot; slicing and chamfering the single crystal silicon ingot; and performing double-side grinding and single-side grinding, respectively, to obtain the original epitaxial wafer.

Further, in the method for reducing defects in an epitaxial wafer, a surface morphology difference of the epitaxial wafer finally formed is less than 25 nm.

Compared with the prior art, the beneficial effects of the present invention mainly include: firstly performing an immersion defect removal process on the original epitaxial wafer, removing a lot of scratches and defects of the original epitaxial wafer, then performing a polishing treatment, and then The surface morphology data of the original epitaxial wafer is collected through analysis, and the morphological data is analyzed to obtain the amount of etching to be performed in different regions of the original epitaxial wafer. The process parameters required for different regions are determined by the amount of etching. Targeted etching removes the amount of to-be-etched in different regions of the original epitaxial wafer, thereby removing defects and scratches on the surface of the original epitaxial wafer, forming an epitaxial wafer with a smooth surface, and further improving the performance of the subsequent epitaxial layer. improve.

10‧‧‧ Suction Cup

11‧‧‧Mini heating unit

20‧‧‧ Nozzle

30‧‧‧Original epitaxial wafer

40‧‧‧ shaft

FIG. 1 is a flowchart of a method for forming defects in an epitaxial wafer according to an embodiment of the present invention; FIG. 2 is a plan view of a suction cup arranged by a matrix of a plurality of micro heating units according to an embodiment of the present invention; In one embodiment of the invention, a schematic diagram of a structure in a process chamber is performed when an original epitaxial wafer is etched in different regions.

The method for reducing epitaxial wafer defects of the present invention will be described in more detail with reference to the schematic diagrams, which shows the preferred embodiments of the present invention. It should be understood in the art The skilled person can modify the invention described herein, while still achieving the advantageous effects of the invention. Therefore, the following description should be understood as widely known to those skilled in the art, and not as a limitation on the present invention.

The invention is described in more detail by way of example in the following paragraphs with reference to the drawings. The advantages and features of the invention will be apparent from the following description and claims. It should be noted that the drawings are in a very simplified form and all use inaccurate proportions, which are only used to facilitate and clearly assist the description of the embodiments of the present invention.

Please refer to FIG. 1. In this embodiment, a method for forming defects in an epitaxial wafer is proposed, including steps: S100: providing an original epitaxial wafer; S200: immersing the initial epitaxial wafer. Defect removal processing; S300: polishing the original epitaxial wafer, S400: detecting the surface morphology of the original epitaxial wafer and saving the morphological data, S500: analyzing the morphological data to obtain Amounts to be etched in different regions of the original epitaxial wafer, and process parameters required for different regions are determined by the amounts to be etched; S600: Etching different regions of the original epitaxial wafer according to required process parameters in different regions To make the surface of the original epitaxial wafer more smooth; S700: performing single-side polishing on the original epitaxial wafer to obtain a final epitaxial wafer.

Specifically, in this embodiment, the step of forming the original epitaxial wafer includes: providing a single crystal silicon ingot; grinding and rounding the single crystal silicon ingot; and forming a positioning on the single crystal silicon ingot. Edge or positioning V-groove; Slicing and chamfering the single crystal silicon ingot; performing double-side grinding and single-side grinding, respectively, to obtain the original epitaxial wafer.

When forming the original epitaxial wafer, the grinding rounding, slicing, chamfering, and double-sided grinding and single-sided grinding will form different degrees of scratches or defects on the surface of the original epitaxial wafer. Not all defects can be removed.

In this embodiment, after the original epitaxial wafer is formed, the immersion defect removal process is first used to immerse the original epitaxial wafer in an etching solution to remove some of the larger scratches or defects. Wherein, the corrosion solution is a mixture of hydrofluoric acid, nitric acid, phosphoric acid, and water, and the mass ratio of HF: HNO ₃ : H ₃ PO ₄ : H ₂ O is 7%: 30%: 35%: 38%, specifically The soaking time can be selected according to different requirements.

After the immersion defect removal process is performed, the original epitaxial wafer is polished, wherein the polishing process includes double-sided polishing and edge polishing.

After the polishing process, first of all, the surface morphology of the original epitaxial wafer is detected, and the topographical data is stored; wherein, the topographical data includes the uniformity of the original epitaxial wafer and the thickness value and unevenness of each region After the morphology data is collected, the morphology data is analyzed to obtain the amount to be etched in different regions of the original epitaxial wafer, and the process parameters required for different regions are determined by the amount to be etched. According to the morphological data, the amount of etching to be etched in each region can be determined, so that a part of the region can be etched to make the formed epitaxial wafer smooth as a whole.

In this embodiment, a single-piece spin-jet wet method is used to etch different regions of the original epitaxial wafer. The process parameters include a process temperature and a process time, wherein the process temperature and the process time can well control different etching amounts.

In order to be able to control the process temperature in different regions, in this embodiment, the resistance heating method is adopted for adjustment by the sucker partition control. Specifically, please refer to FIG. 2. The sucker 10 includes a plurality of micro heating units 11 arranged in a matrix. The number and arrangement of the micro heating units 11 can be selected according to different needs, which is not limited here. The temperature of the unit 11 is controlled separately, so as to control the process temperature of different regions of the entire original epitaxial wafer.

In this embodiment, the micro heating unit 11 may be a Peltier effect device or a resistance heating device. The micro heating unit 11 may be one or more of all suitable materials such as polyimide heaters, silicone rubber heaters, mica heaters, metal heaters, ceramic heaters, semiconductor heaters, or carbon heaters; The micro heating unit 11 can be formed by wire-wound, formed into a foil or stamping type; the power adjustment range of a single micro heating unit 11 is 0 ~ 20W. Optimally, the sucker 10 can cover the original epitaxial crystal. circle.

In addition, as shown in FIG. 3, the single-piece rotary spray wet method sprays the etching solution through the nozzle 20, and the nozzle 20 can move up, down, left, and right. The length of the area spraying time determines the length of the process time. The corrosion solution includes hydrofluoric acid, nitric acid, phosphoric acid, and water. Among them, the mass ratio of HF: HNO ₃ : H ₃ PO ₄ : H ₂ O is 7%: 30%. : 35%: 38%.

The original epitaxial wafer 30 is placed on the chuck 10 during the manufacturing process. The chuck 10 is used to heat the chuck 10, and a rotary shaft 40 is connected to the bottom of the chuck 10 to drive the chuck 10 and the original epitaxial wafer. 30 turns.

After the area of the original epitaxial wafer is etched, scratches and defects on the surface of the original epitaxial wafer are removed to ensure that the final epitaxial wafer has a surface morphology difference of less than 25 nm. Single-sided polishing treatment to obtain a smooth epitaxial surface The wafer is suitable for the growth of the subsequent epitaxial layer, and can ensure the performance of the subsequent epitaxial layer growth.

In summary, in the method for reducing defects in an epitaxial wafer provided by the embodiment of the present invention, an immersive defect removal process is performed on the original epitaxial wafer to remove many scratches and defects on the original epitaxial wafer, and then Then, the polishing process is performed. Then, the topography data of the original epitaxial wafer is collected through analysis, and the topography data is analyzed to obtain the amount to be etched in different regions of the original epitaxial wafer. The required process parameters are targeted etching to remove different areas to be etched in the original epitaxial wafer, thereby removing defects and scratches on the surface of the original epitaxial wafer, forming an epitaxial wafer with a smooth surface, and subsequently forming The performance of the epitaxial layer is improved.

The above are only preferred embodiments of the present invention, and do not play any limiting role on the present invention. Any person skilled in the art, within the scope not departing from the technical solution of the present invention, make any equivalent replacement or modification to the technical solution and technical content disclosed in the present invention without departing from the technical solution of the present invention. The content still falls within the protection scope of the present invention.

S100 ~ S700‧‧‧step

Claims (14)

A formation method for reducing defects in an epitaxial wafer, comprising the steps of: providing an original epitaxial wafer; performing an immersive defect removal process on the initial epitaxial wafer; and polishing the original epitaxial wafer. Processing; detecting the surface morphology of the original epitaxial wafer and storing the morphological data; analyzing the morphological data to obtain the amount to be etched in different regions of the original epitaxial wafer, and passing through the etched Determine the process parameters required in different regions; etch different regions of the original epitaxial wafer according to the required process parameters in different regions, so that the surface of the original epitaxial wafer is smoother; The single-sided polishing is performed to obtain the final epitaxial wafer. The step of forming the original epitaxial wafer includes: providing a single-crystal silicon ingot; grinding and rounding the single-crystal silicon ingot; A positioning edge or a positioning V groove is formed on the ingot; the single crystal silicon ingot is sliced and chamfered; and double-sided grinding and single-side grinding are respectively performed to obtain the original epitaxial wafer. The method for reducing defects in an epitaxial wafer according to claim 1, wherein a single-piece spin-jet wet method is used to etch different regions of the original epitaxial wafer. The method of claim 2, wherein the process parameters include a process temperature and a process time. The method for reducing defects in an epitaxial wafer according to claim 3, wherein the process temperatures of different regions of the original epitaxial wafer are adjusted by using a chuck zone controlled resistance heating method. The method of claim 4, wherein the chuck comprises a plurality of micro heating units arranged in a matrix. The method of claim 5, wherein the micro heating unit is a Peltier effect device or a resistance heating device. The method of claim 5, wherein the micro heating unit is a polyimide heater, a silicone rubber heater, a mica heater, a metal heater, a ceramic heater, or a semiconductor heater. Heater or carbon heater. The method for forming defects in an epitaxial wafer according to claim 5, wherein the micro heating unit is formed by a wire-wound type, a formed foil type, or an imprint type. The method for reducing defects in an epitaxial wafer according to claim 5, wherein a power range of a single micro heating unit is 0 to 20W. The method of claim 3, wherein the processing time is controlled by a single wafer rotation. The method for forming defects in an epitaxial wafer according to claim 3, wherein the single-chip rotary spray wet method sprays an etching solution through a nozzle. The method of forming an epitaxial wafer 11 according to reduction of defects as claimed in claim, wherein said etching solution comprises hydrofluoric acid, nitric acid, phosphoric acid and water, and _{wherein, HF: HNO 3: H 3} PO 4: H 2 O ratio of mass It was 7%: 30%: 35%: 38%. The method of claim 1, wherein the etching solution used in the immersion defect removal process includes hydrofluoric acid, nitric acid, phosphoric acid, and water, wherein HF: HNO ₃ : H ₃ PO ₄ : The mass ratio of H ₂ O is 7%: 30%: 35%: 38%. The method for forming defects in an epitaxial wafer according to claim 1, wherein a surface morphology difference of the finally formed epitaxial wafer is less than 25 nm.