BMD regulation and control method of annealed sheet based on substrate oxygen content Oi

Abstract

The invention relates to a BMD regulation and control method of an annealed wafer based on the oxygen content Oi of a substrate, which belongs to the technical field of silicon wafer processing, and comprises the following operation steps: 1, selecting a nitrogen-doped P-type high-cop substrate on the substrate, with the resistivity of 10 and the oxygen content Oi interval of 10 ppma to 17.5 ppma; 2, the annealed sheet enters a reaction furnace to be heated to 750 DEG C, and the temperature of 750 DEG C is kept for 3 h; and 3, heating to 1200 DEG C at the speed of 5 DEG C / min, and keeping the temperature at 1200 DEG C for 3 hours. And 4, cooling to 750 DEG C at a speed of 3 DEG C / min, and discharging. And 5, detecting tiny defects in the silicon wafer body by adopting an LST method. The device has the advantages of time and labor saving, good operation stability and reliable quality. The problem that BMD appears in the annealing process of the N-doped P-type annealing sheet is solved. Under the condition of different oxygen contents, the same annealing process is adopted, and the regulation and control method of the corresponding BMD is improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer processing, and in particular to a BMD control method of an annealed wafer based on substrate oxygen content 0i. Background Art

[0002] BMD (Bulk micro defect) is a tiny defect in the silicon wafer. It is the oxygen precipitation gradually formed by the interstitial oxygen in the lattice inside the silicon wafer during the thermal process. BMD is of great significance in silicon wafer processing and application, such as stress release inside the silicon wafer and gettering of metal impurities during silicon wafer processing.

[0003] According to the processing requirements of different devices and different processing scenarios, the directional control of silicon wafer BMD is particularly important. Adjusting BMD parameters mainly controls BMD density, DZ zone width and BMD size. There are many factors that affect BMD formation, such as: annealing constant temperature time, heating and cooling rate, COP of annealing wafer substrate, whether nitrogen is doped, oxygen content concentration, etc. Summary of the invention

[0004] The present invention mainly solves the deficiencies in the prior art and provides a BMD control method for an annealing sheet based on the substrate oxygen content Oi, which has the advantages of saving time and labor, good operation stability and reliable quality. The problem of BMD occurring in the annealing process of N-doped P-type annealing sheets is solved. By adopting the same annealing process under different oxygen content conditions, the corresponding BMD control method is improved.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0006] A BMD control method for an annealed sheet based on substrate oxygen content 0i includes the following steps:

[0007] Step 1: Select a nitrogen-doped P-type high-cop substrate with a resistivity of 10 and an oxygen content Oi ranging from 10 ppma to 17.5 ppma.

[0008] Step 2: The annealing sheet enters the reaction furnace and is heated to 750°C, and maintained at a constant temperature of 750°C for 3 hours.

[0009] Step 3: Raise the temperature to 1200°C at 5°C / min and keep constant at 1200°C for 3 hours.

[0010] Step 4: Cool down to 750℃ at 3℃ / min and take out of the furnace.

[0011] Step 5: Use the LST method to detect tiny defects inside the silicon wafer.

[0012] LST method: The full name of LST BMD detection method is Light Scattering Tomography Bulk Micro Defect Analyzer.

[0013] Preferably, when the oxygen content Oi is 10ppma-11ppma, the BMD quantity is at a relatively stable level. The relationship between the oxygen content Oi and BMD is: y=4E+7x+4E+09, i.e., y=4*10 7 x+4*10 9 , y is BMD density, x is oxygen content Oi; when oxygen content Oi is 11ppma~13ppma, the growth rate of BMD will increase rapidly with the increase of oxygen content Oi. The relationship between Oi and BMD is: y=9E+9x-1E+11, that is, y=9*10 9 x-1*10 11 When the oxygen content Oi is 13ppma~17.5ppma, the BMD growth shows a slow linear growth with the increase of oxygen content Oi. The relationship between oxygen content Oi and BMD is: y=2E+9x+2E+09, that is, y=2*10 9 x-2*10 9 .

[0014] Preferably, multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents, with the oxygen content ranging from 11 to 17.5 ppma, are selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The BMD density is then tested simultaneously and the result is obtained by fitting the BMD density with the oxygen content.

[0015] Preferably, the width of the DZ zone is linearly correlated with the oxygen content Oi, and the trend relationship = formula: y = -3.5632x + 32.231, y-width of the DZ zone, x-oxygen content Oi.

[0016] Preferably, multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents, with the oxygen content ranging from 11 to 17.5 ppma, are selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The D2 depth is then tested simultaneously and the result is obtained by fitting the D2 depth with the oxygen content.

[0017] Preferably, the BMD size has a strong linear correlation with the oxygen content Oi, and the trend relationship formula is: y=-3.5632x+32.231, y-BMD size, x-oxygen content Oi.

[0018] Preferably, multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents, with the oxygen content ranging from 11 to 17.5 ppma, are selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The BMD size is then tested simultaneously and the result is obtained by fitting the BMD size with the oxygen content.

[0019] Preferably, after the heat-treated sample is cut and prepared, it is placed in a loading box and enters the loading port of the LST machine. After loading, it is loaded to the area close to the camera, and the crystal micro-defects are scanned by infrared light. The camera records the scanned image and presents a defect density map.

[0020] The present invention can achieve the following effects:

[0021] The present invention provides a BMD control method for an annealing sheet based on the substrate oxygen content 0i, which has the advantages of saving time and labor, good operation stability and reliable quality compared with the prior art. The problem of BMD occurring in the annealing process of N-doped P-type annealing sheets is solved. By adopting the same annealing process under different oxygen content conditions, the corresponding BMD control method is improved. DETAILED DESCRIPTION

[0022] The technical solution of the invention is further specifically described below through embodiments.

[0023] Embodiment: A method for controlling the BMD of an annealed sheet based on the substrate oxygen content Oi comprises the following steps:

[0024] Step 1: Select a nitrogen-doped P-type high-cop substrate with a resistivity of 10 and an oxygen content Oi ranging from 10 ppma to 17.5 ppma.

[0025] Step 2: The annealing sheet enters the reaction furnace and is heated to 750°C, and maintained at a constant temperature of 750°C for 3 hours.

[0026] Step 3: Raise the temperature to 1200°C at 5°C / min and keep constant at 1200°C for 3 hours.

[0027] Step 4: Cool down to 750℃ at 3℃ / min and take out of the furnace.

[0028] Step 5: Use LST method to detect tiny defects in silicon wafers. After the heat-treated samples are cut and prepared, they are placed in the loading box and enter the loading port of the LST machine. After loading, they are loaded to the area close to the camera. The crystal micro-defects are scanned by infrared light, and the camera records the scanned image to present a defect density map.

[0029] When the oxygen content Oi is 10ppma~11ppma, the BMD quantity is at a relatively stable level. The relationship between the oxygen content Oi and BMD is: y=4E+7x+4E+09, that is, y=4*10 7 x+4*10 9 , y is BMD density, x is oxygen content Oi; when oxygen content Oi is 11ppma~13ppma, the growth rate of BMD will increase rapidly with the increase of oxygen content Oi. The relationship between Oi and BMD is: y=9E+9x-1E+11, that is, y=9*10 9 x-1*10 11 When the oxygen content Oi is 13ppma~17.5ppma, the BMD growth shows a slow linear growth with the increase of oxygen content Oi. The relationship between oxygen content Oi and BMD is: y=2E+9x+2E+09, that is, y=2*10 9 x-2*10 9 Multiple silicon wafers with fixed nitrogen doping amount and different oxygen content, ranging from 11 to 17.5 ppma, were selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The BMD density was tested at the same time and the result was obtained by fitting the BMD density with the oxygen content.

[0030] The width of the DZ zone is linearly correlated with the oxygen content Oi, and the trend relationship = formula: y = -3.5632x + 32.231, y-width of the DZ zone, x-oxygen content Oi. Multiple silicon wafers with fixed nitrogen doping and different oxygen contents, ranging from 11 to 17.5 ppma, were selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The DZ depth was tested at the same time and obtained by fitting the DZ depth with the oxygen content.

[0031] The BMD size has a strong linear correlation with the oxygen content Oi, and the trend relationship formula is: y = -3.5632x + 32.231, y-BMD size, x-oxygen content Oi. Multiple silicon wafers with fixed nitrogen doping amount and different oxygen content, with oxygen content ranging from 11 to 17.5 ppma, were selected and subjected to the same heat treatment conditions, i.e. 780℃ for 3 hours and 1000℃ for 16 hours, and the BMD size was tested at the same time, and the result was obtained by fitting the BMD size and oxygen content.

[0032] The various BMD parameters are precisely controlled by adjusting the oxygen content of the substrate. By constructing a linear formula between BMD parameters and Oi, the oxygen content Oi in the substrate can be quantitatively doped according to actual needs.

[0033] In summary, the BMD control method of the annealing sheet based on the substrate oxygen content Oi has the advantages of saving time and labor, good operation stability and reliable quality. The problem of BMD occurring in the annealing process of N-doped P-type annealing sheets is solved. By using the same annealing process under different oxygen content conditions, the corresponding BMD control method is improved.

[0034] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A BMD control method for an annealed sheet based on substrate oxygen content 0i, characterized in that The steps are as follows: Step 1: Select a nitrogen-doped P-type high-cop substrate with a resistivity of 10Ω·cm and an oxygen content Oi range of 10ppma to 17.5ppma; Step 2: The annealed sheet enters the reaction furnace and is heated to 750°C, and maintained at 750°C for 3 hours; Step 3: Raise the temperature to 1200°C at 5°C / min and keep it at 1200°C for 3h; Step 4: Cool down to 750℃ at 3℃ / min and take out of the furnace; Step 5: Use the LST method to detect tiny defects inside the silicon wafer.

2. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 1, characterized in that: When the oxygen content Oi is 10ppma~11ppma, the BMD quantity is at a relatively stable level. The relationship between the oxygen content Oi and BMD is: y=4E+7x+4E+09, that is, y=4*10 7 x+4*10 9 , y is BMD density, x is oxygen content Oi; when oxygen content Oi is 11ppma~13ppma, the growth rate of BMD will increase rapidly with the increase of oxygen content Oi. The relationship between Oi and BMD is: y=9E+9x-1E+11, that is, y=9*10 9 x-1*10 11 When the oxygen content 0i is 13ppma~17.5ppma, the BMD growth shows a slow linear growth with the increase of oxygen content 0i. The relationship between oxygen content 0i and BMD is: y=2E+9x+2E+09, that is, y=2*10 9 x-2*10 9 .

3. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 2, characterized in that: Multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents (ranging from 11 to 17.5 ppma) were selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The BMD density was then tested simultaneously and the result was obtained by fitting the BMD density with the oxygen content.

4. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 1, characterized in that: The width of the DZ zone shows a linear correlation with the oxygen content Oi, and the trend relationship = formula: y = -3.5632x + 32.231, y-the width of the DZ zone, x-the oxygen content Oi.

5. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 4, characterized in that: Multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents (ranging from 11 to 17.5 ppma) were selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The DZ depth was then tested simultaneously and the result was obtained by fitting the DZ depth with the oxygen content.

6. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 1, characterized in that: The size of BMDsize shows a strong linear correlation with the oxygen content Oi, and the trend relationship formula is: y=-3.5632x+32.231, y-BMDsize, x-oxygen content Oi.

7. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 6, characterized in that: Multiple silicon wafers with fixed nitrogen doping amounts and different oxygen contents (ranging from 11 to 17.5 ppma) were selected and subjected to the same heat treatment conditions, i.e. 780°C for 3 hours and 1000°C for 16 hours. The BMD size was then tested at the same time and the result was obtained by fitting the BMD size with the oxygen content.

8. The BMD control method of the annealed sheet based on the substrate oxygen content Oi according to claim 1, characterized in that: After the heat-treated samples are cut and prepared, they are placed in a loading box and enter the loading port of the LST machine. After loading, they are loaded to the area close to the camera. Infrared light is used to scan the micro defects of the crystal. The camera records the scanned image and presents a defect density map.