A method for preparing single-crystal substrates by dividing indium phosphide defective crystal rods.

Abstract

This invention discloses a method for preparing single-crystal substrate wafers by dividing indium phosphide defective crystal rods, comprising the following steps: cutting the head and tail and making angles, marking positioning edges, slicing, avoiding defects, scribing, and edge grinding. This invention, through the sorting of the sliced ​​wafers, can rationally utilize the effective area of ​​each wafer, improving the utilization rate of the single crystal and avoiding the problem of unavoidable defects in the slicing after rod removal and qualitative analysis, thus reducing the risk of uncontrollable factors. This method is flexible, allowing for separate screening and scribing based on different effective areas, reducing wafer scrap and increasing the value of a single wafer. Furthermore, the use of laser cutting saves approximately 94% of material loss compared to the 1.5mm loss of rod removal, resulting in greater time and material savings. It also significantly improves the quality of crystal orientation angles.

Description

Technical Field

[0001] This invention relates to a method for preparing single-crystal substrates by dividing indium phosphide defective crystal rods, belonging to the field of indium phosphide defective crystal rod processing technology. Background Technology

[0002] Indium phosphide (InP) is one of the important III-V compound semiconductor materials, and a new generation of electronic functional materials following Si and GaAs. Indium phosphide possesses many advantages, such as a direct-transition band structure, high electro-optical conversion efficiency and electron mobility, ease of fabrication into semi-insulating materials, suitability for high-frequency microwave devices and circuits, high operating temperature, strong radiation resistance, and high conversion efficiency as a solar cell material. These characteristics determine its wide range of applications in civilian and military fields such as solid-state light emission, microwave communication, fiber optic communication, guidance / navigation, and satellites.

[0003] Indium phosphide (InP) possesses key advantages in two major application areas due to its high electron mobility, good radiation resistance, and large bandgap: (1) photonics: emission and detection capabilities at wavelengths above 1000 nm; (2) radio frequency (RF): high-speed and low-noise performance in high-frequency RF applications. Currently, the real driving force behind the InP wafer market lies in photonic applications.

[0004] Currently, the main specifications of indium phosphide are 2-inch, 3-inch and 4-inch. The crystal is mainly grown in 4-inch crystals. In the existing crystal processing technology, many twin line defects have been found. These defects are extremely fine lines on the surface of the substrate after being cut, with a length ranging from 1 to 100 mm. Some twin lines even run through the entire crystal rod, and most of them have an inclined angle. The location of the twin lines is randomly generated in the edge or center area of ​​the wafer during the crystal production process, making them extremely difficult to detect. The traditional processing method is as follows: cut the head and tail – hollow out the rod – make the angle – roll the outer circle – grind the positioning edge – slice – grind the edge. Since the position of the hollowed-out rod is fixed, it is impossible to make cutting adjustments on this basis. The rounded rod is further reduced in size. Since the appearance detection of internal crystal defects is not clear, the hollowed-out area may contain polycrystalline or twin-line defects, which can easily lead to mis-hollowing or misjudgment. Tilted twin-line defects can also prevent the formation of a crystal rod, making the single crystal unusable. After slicing the hollowed-out rod, a considerable number of wafers may also contain twin-line defects in small areas, resulting in wafer scrap. In other words, the traditional process cannot avoid defects during processing. Therefore, defects often lead to a large number of scrap wafers during processing, which is the main reason for the high production cost. In order to solve this problem, the inventor developed a new process to solve the cutting method that avoids twin-line defects. Summary of the Invention

[0005] This invention provides a method for preparing single-crystal substrates by dividing indium phosphide defective crystal rods. Through improvements to the method, crystal rod defects can be effectively avoided, the effective utilization rate of single crystals can be improved, and costs can be reduced.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod includes the following steps:

[0008] 1) Cut off the head and tail of the crystal rod, and make the angle of the head

[100] end face of the crystal rod as required;

[0009] 2) Cut a sample with a thickness of 0.5-1.5 mm from the head of the crystal rod, etch it with hydrochloric acid for 2-5 minutes, rinse it with water and dry it. Observe the cell orientation under a microscope with a 10X objective lens to determine the [0-1-1] crystal orientation of the cell. Use a surface grinder to grind a 5-10 mm wide OF positioning flat edge at the edge of the [0-1-1] crystal orientation of the crystal rod as a mark.

[0010] 3) Position and slice the processed crystal rod on a multi-wire dicing machine to cut it into wafers of uniform thickness;

[0011] 4) Inspect all the wafers, avoid defects, mark the shape of the defect-free and qualified wafers, and perform cleavage according to the markings in step 2) to obtain cleavage flat edges;

[0012] 5) Using the cleavage flat edge as the positioning edge, the marked qualified areas of the wafer are cut into 2-inch, 3-inch or 4-inch blank wafers using a laser scribing machine.

[0013] 6) After grinding the edges of the indium phosphide blank wafers, qualified 2-inch, 3-inch or 4-inch wafers are obtained.

[0014] In step 1), the angle is set according to the customer's requirements. The accuracy range required by the customer is usually around 0.01° to 0.2°.

[0015] In step 2), when sawing the sample, the saw blade is perpendicular to the height direction of the crystal rod.

[0016] The indium phosphide fractionation preparation method of the present invention can effectively avoid single crystal defects.

[0017] As is common knowledge, the

[100] plane is the surface of the wafer, the OF flat edge is the large edge, and the OF flat edge direction is the [0-1-1] direction.

[0018] The design steps of this invention are: cutting the head and tail and making angles—marking the positioning edges—slicing—avoiding defects—dicing—grinding. This allows a 4-inch defective wafer to be transformed into a 2-inch, 3-inch, or 4-inch defect-free substrate wafer using the method of this invention. This invention evaluates the effective area of ​​the wafer on the surface of the single crystal. After dividing the crystal rod, it eliminates the need for rod hollowing and outer diameter processing, directly using multi-wire cutting to slice. By measuring the effective area position, defects can be avoided. The 2-inch, 3-inch, or 4-inch cutting areas are marked, and then OF flat edges are cut according to the substrate markings. This perfectly avoids twin-line defects, achieving non-destructive single crystal processing.

[0019] In existing processes, polycrystalline or twin-crystal defects in indium phosphide lead to scrap in the following two situations: 1) Ingot defects: Large-angle tilted twin-crystal defects or multiple twin-crystal defects. These defects are relatively common, appearing in about 60% of crystals. Such ingots cannot be fully utilized to create a qualified substrate by removing the ingot itself; only a portion of the effective area can be used. 2) Wafer defects: After the ingot is shaped, the wafer shape cannot be adjusted to avoid defects. The presence of partially hidden twin-crystal defects or small internal polycrystalline structures after dicing results in wafer scrap. This invention, however, can utilize single crystals containing some defects, maximizing the effective area of ​​the single crystal ingot to process into single wafers.

[0020] To further improve the utilization rate of the crystal rod, in step 1) above, during the head and tail removal, the blade rotation speed is 500–5000 r / min, the cutting speed is 1–20 mm / min, the cutting depth is 50–120 mm, and the water flow rate is 100–600 ml / min. No temperature requirement is placed during the head and tail removal.

[0021] To further improve the utilization rate of crystal rods, in step 1), when making the angle, the ambient temperature is 15-28℃, the blade rotation speed is 500-5000r / min, the cutting speed is 1-20mm / min, the cutting depth is 50-120mm, the cutting accuracy is 0.01-0.5°, and the water flow rate is 100-600ml / min.

[0022] To further improve the utilization rate of crystal rods, in step 2), when marking, the ambient temperature is 15-28℃, the blade rotation speed is 500-5000 r / min, the cutting speed is 0.01-0.1 mm / min, the cutting depth is 0.1-2 mm, the cutting accuracy is 0.1-0.5°, and the water flow rate is 100-600 ml / min.

[0023] To further improve efficiency, in step 3), the ambient temperature during slicing is 20-26℃, the mass ratio of silicon carbide powder to cutting fluid is (1.1-2):1, the blade rotation speed is 200-1000 r / min, the cutting speed is 1-10 mm / min, the cutting depth is 50-120 mm, the cutting accuracy is 0.01-0.5°, and the flow rate of the cutting fluid is 300-3000 ml / min.

[0024] To further improve product quality, in step 4), the ambient temperature during cleavage is 15–28℃, the blade rotation speed is 1–5 r / min, the cutting speed is 1–50 times / min, and the cutting depth is 0.1–1 mm.

[0025] To further balance efficiency and quality, in step 5), the laser temperature is high during laser scribing. If the ambient temperature is too low, the wafer will break open. The ambient temperature is set to 20-26℃, the frequency to 20-100Hz, the cutting speed to 10-500 times / min, and the cutting depth to 0.3-1mm.

[0026] To facilitate control and ensure the edge grinding effect, in step 6), the ambient temperature is 15-28℃, the blade speed is 500-5000 r / min, the cutting speed is 1-10 mm / min, the cutting depth is 0.2-2 mm, the cutting accuracy is 0.01-0.5°, and the water flow rate is 100-1000 ml / min.

[0027] This invention discloses a method for preparing single-crystal substrate wafers by dividing indium phosphide defective crystal rods. After dividing the crystal rods by evaluating the effective area of ​​the wafer on the surface of the single crystal, the rod-cutting and outer circle processing are eliminated. Direct multi-wire cutting is used to cut the wafers, and then the substrates are effectively marked and cut. A blank wafer is obtained by laser scribing based on the marked positions. Finally, the finished indium phosphide wafer is obtained by edge grinding. This method can perfectly avoid twin-line defects and achieve non-destructive processing of single crystals.

[0028] Any techniques not mentioned in this invention are based on existing technologies.

[0029] This invention discloses a method for preparing single-crystal substrate wafers by dividing indium phosphide defective crystal rods. Based on existing processes, it reduces the steps of rod removal and outer diameter machining, and introduces a new process route involving sorting, marking, cutting, and laser scribing. Compared to traditional processing methods, it has the following advantages: 1. By sorting the wafers after cutting, the effective area of ​​each wafer can be rationally utilized, improving the utilization rate of single crystals and avoiding the problem of unavoidable defects in the slicing after rod removal and qualitative analysis, thus reducing the risk of uncontrollable factors; 2. This method is more flexible, allowing for separate screening and scribing based on different effective areas, reducing wafer scrap. Since larger wafers have higher value (3-inch wafers are more valuable than 2-inch wafers), sorting based on defect location identifies wafers suitable for 2-inch or 3-inch processing, increasing the value per wafer; 3. It utilizes the relatively mature laser cutting technology, with a kerf of approximately 0.1mm, saving about 94% of material loss compared to the 1.5mm loss of rod removal, resulting in greater time and material savings; 4. It significantly improves the quality of crystal orientation angles. Attached Figure Description

[0030] Figure 1 A schematic diagram of a crystal sample with twin-line defects produced by VGF.

[0031] Figure 2 To be Figure 1 A schematic diagram of the processing steps for crystal rods: "cutting the head and tail and making angles - making positioning edge marks - slicing".

[0032] Figure 3 To be Figure 2 A schematic diagram of the processing steps of "defect avoidance - scribing - edge grinding" for the obtained slices;

[0033] Figure 4 This is a schematic diagram of the wafer. 1 represents the wafer surface in the

[100] direction, 2 represents the OF flat edge in the [0-1-1] direction (positioning edge), and 3 represents the IF flat edge in the [0-11] direction (small edge). Detailed Implementation

[0034] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0035] Example 1

[0036] Take the common indium phosphide twin-wire defect as an example: due to the tilted penetration of the twin wire, traditional ingot-cutting processes are no longer suitable for processing and producing indium phosphide with this type of defect. Figure 1As shown, the crystal rod is a circular blank, approximately 100mm in height (length) and 103-105mm in diameter, with a 4-inch specification. It has two triple crystal lines. The traditional processing method is to vertically hollow out the rod from the conical part to prepare a 2-inch (3-inch) specification. Due to the angle requirements, it is impossible to completely avoid defects, resulting in the single crystal not being used well. In this example, the following method is used to divide and prepare a single crystal substrate:

[0037] 1) After removing the head and tail of the crystal rod, the length of the crystal rod is 72mm. Check whether there are defects on the end face cutting surface. Orient the complete area of ​​the

[100] end face on X-ray. The orientation accuracy is controlled at 0.03°. Use MB TS206 internal circular saw to cut flat at a speed of 15mm / min. Make an angle of 0.07±0.05°. Make an angle of 31°39′45″ in the positive crystal direction and 31°44′05″ in the off-crystal direction. After removing the invalid area at the head and tail, make an angle to complete the crystal rod length of 68mm.

[0038] 2) A small sample with a thickness of 0.8 mm was cut out from the inner circle of the

[100] direction of the crystal rod using MB TS206. It was etched with hydrochloric acid (a mixture of 35% hydrochloric acid and water) for 5 min, rinsed with water for 2 min, dried, and the cell direction was observed under a microscope with a 10X objective lens. It can be observed that the cell direction is perpendicular to the horizontal direction on one side and parallel to the horizontal direction on the other side. The [0-1-1] crystal direction of the cell was determined as the OF positioning flat edge. A 12 mm wide OF positioning flat edge was ground at the edge of the [0-1-1] crystal direction of the crystal rod as a mark.

[0039] 3) The processed crystal rods were glued to the crystal drag and cured with AB glue. The (100) plane was adjusted to the range of 0.01° to 0.5° on the Gao Niao 610SD multi-wire slicing machine and multi-wire slicing was performed to cut wafers with a thickness of 480μm. The slurry was prepared by mixing 1500 mesh silicon carbide powder from Liuhe Gap Powder Co., Ltd. and cutting fluid (model JX-8A, Shaanxi Petrochemical Research Institute) in a mass ratio of 1.5:1. After slicing, the glue was removed and the surface was cleaned to obtain 113 wafers with a thickness of 480μm. The data obtained by sampling and testing are as follows;

[0040] Film number BOW WARP TTV TIR LTIR LTV 1 0.832 17.745 2.919 2.128 0.827 1.221 20 -2.113 19.788 2.915 2.603 1.427 0.869

[0041] 4) Inspect the defect locations on the wafer surface and mark them, avoiding the defects. Mark the shape of the defect-free qualified wafers. Use a diamond pen to draw a 2-4mm notch on the edge of the (0-1-1) marked position, avoiding the defects. Break along the notch to get a cleavage flat edge. Mark 36 3-inch wafers and 77 2-inch wafers.

[0042] 5) Using the cleavage flat edge as the positioning edge, avoiding the 2-inch mark position of the defect, use the Kehanlong laser scribing machine to scribing and cut according to the outline drawn in step 4), leaving a processing allowance of 0.2 to 2 mm during scribing and cutting;

[0043] 6) The diameter of the indium phosphide blank wafers was measured and found to be within the acceptable range. On a WGM4200 edge grinding machine, the edges were ground into finished products using a forming grinding wheel groove with an R0.1~R0.5mm diameter. A total of 77 2-inch wafers and 36 3-inch wafers were obtained. The X-ray orientation instrument produced by Dandong New Oriental Crystal Instrument Co., Ltd. was used to measure the angles. The 2-inch OF flat edge was measured to have an angle of 21°45′36″ and an IF(0-11) measurement of 21°43′34″, which is within the acceptable range. The 3-inch OF flat edge crystal orientation was measured to be 31°45′42″ and an IF(0-11) measurement of 21°44′12″, which is within the acceptable range.

[0044]

[0045] Parameters of each step in Example 1

[0046]

[0047]

[0048] By adjusting the scheme and removing the rounding process of the scouring rod, we can add sorting and defect avoidance, introduce laser cutting technology, and avoid defects during dicing. The defect-avoidance sorting method can avoid the defect location and dicing out qualified wafers, thus improving the wafer yield. The kerf of laser cutting is about 0.1mm, which saves about 94% of material loss compared to the 1.5mm loss of the scouring rod.

[0049] Comparative Example 1

[0050] The defective crystal rod is processed using existing methods. The crystal rod is a round blank with a height (length) of about 100 mm and a diameter of 103-105 mm, which is 4 inches in size. It has two or three twin lines. The defect is similar to that in Example 1. The processing steps include: cutting off the head and tail, hollowing out the rod, making the angle, rolling the outer circle, grinding the positioning edge, slicing and grinding the edge. Hollowing out the rod and rolling the outer circle can be carried out according to conventional methods. The parameter requirements for the remaining steps are the same as those in Example 1.

[0051] Comparison of the pass rates of Example 1 and Comparative Example 1:

[0052] Processing methods Ingot numbering Ingot length Production film 2-inch film 3-inch film Defective film Finished Product Rate Example 1 IF20032-1 68 113 77 36 0 100.00％ Comparative Example 1 IS20023 65 108 49 0 59 45.37％

[0053] Accuracy comparison between Example 1 and Comparative Example 1

[0054]

[0055] A wafer OF flat edge of ≤0.05° is considered a high-precision crystal orientation. As can be clearly seen from the table above, this application significantly improves the quality of the crystal orientation angle.

[0056] Comparative Example 2

[0057] The ambient temperature of the laser scribing was increased to 30-35°C, and all other parameters were the same as in Example 1. A total of 75 2-inch wafers and 36 3-inch wafers were obtained.

[0058] Comparative Example 3

[0059] The ambient temperature for laser scribing was reduced to 10-15°C, while all other aspects were handled in accordance with Example 1, resulting in a total of 64 2-inch wafers and 33 3-inch wafers.

Claims

1. A method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod, characterized in that: Includes the following steps: 1) Cut off the head and tail of the crystal rod, and make the angle of the head [100] end face of the crystal rod as required; 2) Cut a sample with a thickness of 0.5-1.5 mm from the head of the crystal rod, etch it with hydrochloric acid for 2-5 minutes, rinse it with water and dry it. Observe the cell orientation under a microscope with a 10X objective lens to determine the [0-1-1] crystal orientation of the cell. Use a surface grinder to grind a 5-10 mm wide OF positioning flat edge at the edge of the [0-1-1] crystal orientation of the crystal rod as a mark. 3) Position and slice the processed crystal rod on a multi-wire dicing machine to cut it into wafers of uniform thickness; 4) Inspect all the wafers, avoid defects, mark the shape of the defect-free and qualified wafers, and perform cleavage according to the markings in step 2) to obtain cleavage flat edges; 5) Using the cleavage flat edge as the positioning edge, use a laser scribing machine to scribing and cutting along the outline of the marked defect-free qualified wafer into 2-inch, 3-inch or 4-inch blank wafers. 6) After grinding the edges of the indium phosphide blank wafers, qualified 2-inch, 3-inch or 4-inch wafers are obtained. In step 3), during slicing, the ambient temperature is 20-26℃, the mass ratio of 1500 mesh silicon carbide powder to cutting fluid is (1.1-2):1, the blade rotation speed is 400-1000 r / min, the cutting speed is 5-10 mm / min, the cutting depth is 50-120 mm, the cutting accuracy is 0.01-0.5°, and the flow rate of cutting fluid is 300-3000 ml / min. In step 4), during cleavage, the ambient temperature is 15–28℃, the blade rotation speed is 1–5 r / min, the cutting speed is 1–50 times / min, and the cutting depth is 0.1–1 mm. In step 5), the ambient temperature during laser scribing is 20–26°C.

2. The method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod as described in claim 1, characterized in that: In step 1), when removing the head and tail, the blade rotation speed is 500-5000 r / min, the cutting speed is 1-20 mm / min, the cutting depth is 50-120 mm, and the water flow rate is 100-600 ml / min.

3. The method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod as described in claim 1 or 2, characterized in that: In step 1), when making the angle, the ambient temperature is 15-28℃, the blade rotation speed is 500-5000r / min, the cutting speed is 1-20mm / min, the cutting depth is 50-120mm, the cutting accuracy is 0.01-0.5°, and the water flow rate is 100-600ml / min.

4. The method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod as described in claim 1 or 2, characterized in that: In step 2), when marking, the ambient temperature is 15-28℃, the blade rotation speed is 500-5000r / min, the cutting speed is 0.01-0.1mm / min, the cutting depth is 0.1-2mm, the cutting accuracy is 0.1-0.5°, and the water flow rate is 100-600ml / min.

5. The method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod as described in claim 1 or 2, characterized in that: In step 5), the laser scribing frequency is 20-100 Hz, the cutting speed is 10-500 times / min, and the cutting depth is 0.3-1 mm.

6. The method for preparing a single-crystal substrate by dividing an indium phosphide defective crystal rod as described in claim 1 or 2, characterized in that: In step 6), during edge grinding, the ambient temperature is 15-28℃, the blade rotation speed is 500-5000 r / min, the cutting speed is 1-10 mm / min, the cutting depth is 0.2-2 mm, the cutting accuracy is 0.01-0.5°, and the water flow rate is 100-1000 ml / min.

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