CN-122013311-A - Epitaxial growth method for adjusting height gradient between wafer and graphite base in real time

CN122013311ACN 122013311 ACN122013311 ACN 122013311ACN-122013311-A

Abstract

The invention relates to an epitaxial growth method for adjusting the height gradient between a wafer and a graphite base in real time, which comprises the following steps of S1, installing an optical thickness analysis system above a glass observation window of a reaction chamber of epitaxial equipment, S2, starting the optical thickness analysis system after a certain thickness of a film grows on a first batch of wafers, measuring the height gradient standard value of each wafer and the graphite base, S3, measuring the height gradient test value of each wafer and the graphite base on a next batch of wafers by the same method as the step S2, and adjusting the air flow of each planetary disk in real time in the test process, thereby adjusting the difference value between each height gradient test value and the height gradient standard value corresponding to the step S2, and S4, putting a batch of wafers again for epitaxial film growth each time, and carrying out test adjustment according to the step S3. The method can realize the dynamic adjustment of the wafer plane and inhibit the trend of increasing the height gradient of the top surface of the wafer and the top surface of the graphite base.

Inventors

WANG LIANGJUN
WANG ZHENHUA
XIA WEI
XIN XIN
ZHAO KAIDI

Assignees

山东华光光电子股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (10)

1. An epitaxial growth method for adjusting the height gradient between a wafer and a graphite susceptor in real time is characterized by comprising the following steps: s1, installing an optical thickness analysis system above a glass observation window of a reaction chamber of epitaxial equipment; S2, placing a first batch of wafers in a reaction chamber, setting the blowing air flow proportion of each planetary disc and the initial air flow of each planetary disc, controlling the temperature of the reaction chamber, growing a film on the wafers, starting an optical thickness analysis system after growing a film with a certain thickness, measuring the height gradient of each wafer and a graphite base, measuring each height gradient for a plurality of times, and calculating the average value of each height gradient as a height gradient standard value; S3, putting a batch of wafers into the reaction chamber again, setting the same planetary disc purge air flow proportion, planetary disc initial air flow and reaction chamber temperature as in the step S2, growing epitaxial films on the wafers, starting an optical thickness analysis system after each film with the same thickness as in the step S2 is grown, measuring the height gradient of each wafer and a graphite base, measuring each height gradient for a plurality of times, calculating the average value of each height gradient as a height gradient test value, adjusting the air flow of each planetary disc in real time in the test process, adjusting the difference value between each height gradient test value and the height gradient standard value corresponding to the step S2, taking out the wafers from the reaction chamber after the growth of the epitaxial films is completed, and obtaining the wafer with the height gradient higher than that of the epitaxial films in the step S2 S4, subsequently, putting a batch of wafers again each time for epitaxial film growth, and performing test adjustment according to the step S3.
2. The epitaxial growth method for adjusting the height gradient between a wafer and a graphite susceptor in real time according to claim 1, wherein in the step S1, the optical thickness analysis system performs optical analysis using the law of poloxamer.
3. The method for epitaxial growth with real-time adjustment of the height gradient between a wafer and a graphite susceptor according to claim 1, wherein in the step S1, the measurement range of the optical thickness analysis system in the horizontal direction is 120±40mm, and further preferably, the measurement range of the optical thickness analysis system in the horizontal direction is 150mm.
4. The epitaxial growth method for adjusting the height gradient between the wafer and the graphite susceptor in real time according to claim 1, wherein in the step S1, a light source is disposed at the bottom center of the optical thickness analysis system, and the light source is located at a distance of 40±20mm from the top of the glass viewing window in the vertical direction, and preferably, the light source is located at a distance of 50mm from the top of the glass viewing window in the vertical direction.
5. The epitaxial growth method for adjusting the height gradient between the wafer and the graphite susceptor in real time according to claim 1, wherein in the step S2, the purge gas flow ratio of each planetary tray is set to N 2 :H 2 = 0-17, the initial gas flow ratio of each planetary tray is set to 50-500 sccm, the wafer is higher than the graphite susceptor, the height gradient of the wafer and the graphite susceptor is 10-200 μm, the height gradient is reduced on the premise of ensuring the autorotation of the planetary tray, thereby reducing the edge defect effect of the epitaxial film, further preferably, the purge gas flow ratio of each planetary tray is set to N 2 :H 2 = 0-2, the initial gas flow ratio of each planetary tray is set to 50-150 sccm, the height gradient of the wafer and the graphite susceptor is set to 10-60 μm, most preferably, the initial gas flow ratio of each planetary tray is set to N 2 :H 2 = 1, and the height gradient of the wafer and the graphite susceptor is 20-30 μm.
6. The method for epitaxial growth by adjusting the height gradient between a wafer and a graphite susceptor in real time according to claim 1, wherein in the step S2, an optical thickness analysis system is started after a thin film of 0.5-12 μm is grown on the wafer and a thin film of 0.1-6 μm is grown, and further preferably, an optical thickness analysis system is started after a thin film of 8 μm is grown on the wafer and a thin film of 4 μm is grown.
7. The method for epitaxial growth with real-time adjustment of the height gradient between a wafer and a graphite susceptor according to claim 1, wherein in the step S2, the initial angle of the graphite susceptor is 0 ° -180 ° when the optical thickness analysis system is started, and further preferably, the initial angle of the graphite susceptor is 0 °.
8. The epitaxial growth method for adjusting the height gradient between the wafer and the graphite susceptor in real time according to claim 1, wherein in the step S2, each height gradient is measured 10-15 times, each height gradient is measured for 12-180S, and further preferably, each height gradient is measured 12 times, and each height gradient is measured for 60S.
9. The method for epitaxial growth for adjusting the height gradient between the wafer and the graphite susceptor in real time according to claim 8, wherein in the step S3, the number of times and the period of each height gradient measurement are the same as those in the step S2.
10. The epitaxial growth method for adjusting the height gradient between the wafer and the graphite susceptor in real time according to claim 1, wherein in the step S3, the air flow of each planetary tray is adjusted in real time during the test, so as to adjust the difference between each height gradient test value and the height gradient standard value corresponding to the step S2 to be ±1 μm, further preferably adjust the difference between each height gradient test value and the height gradient standard value corresponding to the step S2 to be ±0.5 μm, and most preferably adjust the difference between each height gradient test value and the height gradient standard value corresponding to the step S2 to be ±0.2 μm.

Description

Epitaxial growth method for adjusting height gradient between wafer and graphite base in real time Technical Field The invention relates to an epitaxial growth method for adjusting the height gradient between a wafer and a graphite base in real time, and belongs to the technical field of epitaxial growth. Background The epitaxial equipment adopts an organic metal chemical vapor deposition technology to grow a film with the height consistent with the crystal structure on a wafer, and the film is a core base material of the semiconductor industry and is widely applied to the fields of electronic equipment chips, high-power devices, microwave radio frequency and the like. The height gradient between the wafer on the planetary plate and the graphite susceptor in the reaction chamber of the epitaxial apparatus is generally fixed, and the height gradient between the wafer on the planetary plate and the graphite susceptor during growth can cause interference to the wafer edge gas flow and temperature, resulting in poor edge epitaxy quality. When the surface of the wafer is lower than or flush with the edge of the graphite base, an air flow disturbance or detention area is easily generated at the step of the edge of the wafer, the reactant transportation uniformity is affected, the heat loss of the edge of the wafer is serious, a radial temperature gradient is formed, the thickness of an epitaxial layer and the doping are uneven, and when the surface of the wafer is slightly higher than the edge of the graphite base, the wafer and the graphite base are favorably and rotatably matched, a stable and uniform laminar flow is formed, and the vortex is reduced. And the heat dissipation from the edge of the wafer to the low-temperature environment can be effectively reduced, and the radial temperature uniformity is improved. The mainstream optimization scheme in the current industry is to increase the height of the planetary disc and reduce the groove depth of the carrier disc, but as the epitaxial growth period increases, the thickness of the material in the center of the graphite base is continuously increased, so that the height gradient between the wafer and the graphite base is dynamically amplified along with epitaxial growth. Therefore, the dynamic adjustment of the height gradient between the wafer and the graphite base is realized, and plays a key role in optimizing the radial uniformity of the epitaxial film. Disclosure of Invention Aiming at the defects of the prior art, the invention provides the epitaxial growth method for adjusting the height gradient between the wafer and the graphite base in real time, which can realize the dynamic adjustment of the height gradient between the wafer and the graphite base, thereby reducing the edge defect effect of the epitaxial film and finally improving the radial uniformity of the epitaxial film. Description of the terminology: EpiCurve TT system is an in-situ optical metering monitoring system developed by Germany LayTec company, and is mainly used for monitoring epitaxial growth process in real time in semiconductor film growth equipment such as metal organic chemical vapor deposition, molecular beam epitaxy and the like. The technical scheme of the invention is as follows: the invention provides an epitaxial growth method for adjusting the height gradient between a wafer and a graphite base in real time, which comprises the following steps: s1, installing an optical thickness analysis system above a glass observation window of a reaction chamber of epitaxial equipment; S2, placing a first batch of wafers in a reaction chamber, setting the blowing air flow proportion of each planetary disc and the initial air flow of each planetary disc, controlling the temperature of the reaction chamber, growing a film on the wafers, starting an optical thickness analysis system after growing a film with a certain thickness, measuring the height gradient of each wafer and a graphite base, measuring each height gradient for a plurality of times, and calculating the average value of each height gradient as a height gradient standard value; S3, a batch of wafers are put in the reaction chamber again, the same planetary disc purge air flow proportion, planetary disc initial air flow and reaction chamber temperature as in the step S2 are set, epitaxial films are grown on the wafers, an optical thickness analysis system is started after the films with the same thickness as the step S2 are grown, the height gradients of each wafer and a graphite base are measured, each height gradient is measured for a plurality of times, an average value of each height gradient is calculated as a height gradient test value, the air flow of each planetary disc is adjusted in real time in the test process, and therefore the difference value between each height gradient test value and the height gradient standard value corresponding to the step S2 is adjusted, and after the epitaxial film growth of the batch