TW202325878A - Method for restarting epitaxial growth equipment - Google Patents

Abstract

The invention provides an epitaxial growth equipment restarting method, and belongs to the technical field of semiconductor manufacturing. The restarting method of the epitaxial growth equipment comprises the following steps: injecting hydrogen into a reaction cavity arranged in the epitaxial growth equipment and purging the hydrogen for a preset time; placing a wafer on a base in the reaction cavity; etching gas is introduced into the reaction cavity at the first temperature, the flow is 15 SLM to 20 SLM, and the duration time is 30 s to 40 s; silicon source gas is introduced into the reaction cavity at the second temperature, the flow ranges from 20 SLM to 30 SLM, and the duration time ranges from 40 s to 60 s; after the epitaxial wafer is grown, the minority carrier MCLT of the epitaxial wafer is measured, and when the MCLT reaches a preset value, restarting of the epitaxial growth equipment is completed. According to the technical scheme, the productivity of the epitaxial wafer can be improved.

Description

Restart method of epitaxial growth equipment

The invention belongs to the technical field of semiconductor manufacturing, in particular to a method for restarting epitaxial growth equipment.

At present, epitaxial wafers play a pivotal role in the integrated circuit industry. The epitaxial growth process of wafers is to perform chemical vapor deposition (Chemical Vapor Deposition, CVD) on the surface of polished wafers, using trichlorosilicon (Trichlorosilane, TCS) and other silicon gaseous compounds react with hydrogen on the surface of the heated silicon substrate or thermally decompose themselves, reduce to silicon, and deposit on the surface of the silicon substrate in the form of a single crystal: SiHCl ₃ + H ₂ →Si↓ + 3HCl.

Compared with polished wafers, epitaxial wafers have lower oxygen content, carbon content, and defect density, and can better control thickness and resistivity. They have metal gettering and good electrical conductivity, and are widely used in highly integrated Integrated Circuit (Integrated Circuit, IC) devices, etc.

During the growth process of the epitaxial layer, the chamber of the epitaxial growth equipment contains a large amount of moisture, and the moisture includes metal impurities generated during the epitaxial growth process at high temperature. If there are metal impurities in the cavity, the metal impurities occupy certain energy levels in the energy gap, and these energy levels will become the recombination centers of excess carriers, thereby reducing the lifetime of the minority carriers (Minority Carrier Life Time, MCLT) , it is impossible to manufacture epitaxial wafers that meet the requirements. Therefore, after the epitaxial growth is completed, preventive maintenance (PM) needs to be performed on the epitaxial growth equipment to meet the environment required for the next production. After PM, there will be residual moisture and metal impurities in the epitaxy equipment machine. At this time, the epitaxy furnace needs to be restarted in order to manufacture epitaxy wafers.

When performing the restart program of the epitaxial growth system, the wafer quality is ensured by continuously repeating the steps of ventilating, heating and stabilizing in the chamber, so as to execute the restart program. However, after restarting, there are still many metal contaminants in the thermally stable state in the epitaxial reaction chamber. In order to make the MCLT value of the epitaxial wafer obtained by the metal contamination test reach the set value, it takes a long enough time to carry out the epitaxial reaction chamber. Baking and transfer, which will reduce the productivity of epitaxial wafers.

In order to solve the above technical problems, the present invention provides a method for restarting epitaxial growth equipment, which can improve the productivity of epitaxial wafers.

In order to achieve the above purpose, the technical solution adopted in the embodiment of the present invention is: a method for restarting epitaxy growth equipment, comprising: injecting hydrogen gas into the reaction chamber set in the epitaxy growth equipment and purging the hydrogen gas for a predetermined time; Placed on the base inside the reaction chamber; feed the etching gas into the reaction chamber at the first temperature, the flow rate is 15SLM (StandardLiter/Minute, standard liter/minute) ~ 20SLM, and the duration is 30s (seconds) ~ 40s; feed the silicon source gas into the reaction chamber at the second temperature, the flow rate is 20SLM~30SLM, and the duration is 40s~60s; measure the MCLT of the epitaxial wafer after growing the epitaxial wafer, when the MCLT reaches the predetermined value, The restart of the epitaxial growth equipment is completed.

In some embodiments, after placing the wafer on the susceptor inside the reaction chamber, the method further includes: heating the reaction chamber to a predetermined first temperature, and then stabilizing the reaction chamber.

In some embodiments, the first temperature is 1100°C-1200°C.

In some embodiments, the second temperature is 1075°C-1175°C.

In some embodiments, the silicon source gas is trichlorosilane gas;

The etching gas is HCL (hydrochloric acid, hydrogen chloride).

In some embodiments, measuring the MCLT of the epitaxial wafer after growing the epitaxial wafer further includes repeating the steps of removing the epitaxial wafer from the reaction chamber after manufacturing the epitaxial wafer and cleaning the reaction chamber until the MCLT reaches a predetermined value.

In some embodiments, the step of measuring the MCLT of the epitaxial wafer is performed during multiple runs, wherein the process of manufacturing one epitaxial wafer is referred to as a run.

In some embodiments, epitaxial wafers corresponding to 50, 100, 150, 200, 250, 300, 350, and 400 runs were taken as sample wafers and MCLT values were measured.

The beneficial effect of the present invention is: in this embodiment, by changing the feed flow rate and feed time of etching gas and silicon source gas, the moisture and metal impurities in the reaction chamber can be removed at a faster rate, so it can reduce the The MCLT is set to the time required to perform the re-operation of the epitaxial growth apparatus, and thus, the production efficiency of the epitaxial wafer can be improved.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the following will clearly and completely describe the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. Apparently, the described embodiments are some, not all, embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art belong to the protection scope of the present invention.

In describing the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. indicate The orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation or be configured in a specific orientation. and operation, and therefore should not be construed as limiting the invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In related technologies, after the epitaxy growth equipment is restarted, the metal impurities remaining in the process of etching and growing the film cannot be effectively eliminated, thereby affecting the time required for MCLT to return to the set value, and the restart time of the epitaxy growth equipment is also affected , thereby affecting the production efficiency of epitaxial wafers.

In order to solve the above technical problems, the present invention provides a method for restarting epitaxial growth equipment, which can improve the productivity of epitaxial wafers.

An embodiment of the present invention provides a method for restarting epitaxial growth equipment, as shown in FIG. 1 , including: Step S101: injecting hydrogen into the reaction chamber set in the epitaxial growth equipment and purging the hydrogen for a predetermined time. Specifically, it can be During the entire restart process, hydrogen is continuously fed into the reaction chamber, and the moisture and substances in the reaction chamber can be more effectively discharged through the transfer of hydrogen; step S102: placing the wafer on the base inside the reaction chamber; Feed etching gas into the reaction chamber at a temperature of 15SLM-20SLM for a duration of 30-40s; in some embodiments, the flow rate of etching gas can be 15SLM, 16SLM, 17SLM, 18SLM, 19SLM or 20SLM. The duration of feeding the etching gas may be 30s, 32s, 34s, 36s, 38s or 40s.

Step S103: Introduce the silicon source gas into the reaction chamber at the second temperature, the flow rate is 20SLM~30SLM, and the duration is 40s~60s; in some embodiments, the flow rate of the silicon source gas can be 20SLM, 22SLM, 24SLM, 26SLM , 28SLM or 30SLM. The duration of feeding the silicon source gas can be 40s, 45s, 50s, 55s, 58s or 60s.

Step S104: measure the MCLT of the epitaxial wafer after growing the epitaxial wafer, and restart the epitaxial growth equipment when the MCLT reaches a predetermined value.

In this embodiment, by changing the feed flow rate and feed time of etching gas and silicon source gas, the moisture and metal impurities in the reaction chamber can be removed at a faster rate, so it can be reduced to reach the set value of MCLT to perform epitaxy. The time required to re-operate the growth equipment, therefore, can improve the production efficiency of epitaxial wafers.

As shown in FIG. 2 , the epitaxial reaction device 100 of this embodiment includes a reaction chamber, and further includes: an air inlet 101 , an air outlet 102 , and a base 103 located in the reaction chamber. The susceptor 103 is a portion on which the wafer is mounted when the epitaxy process is performed, and the susceptor 103 may be composed of a plate made of a material such as carbon graphite or silicon carbide. The base 103 is supported by a main shaft located at the lower part of the base 103 and a base support, and the base support is provided at various positions of the main shaft along the edge direction of the base 103 .

The epitaxial film is vapor grown on the wafer at high temperature in the reaction chamber of the epitaxial reaction equipment, and the epitaxial wafer is obtained after the epitaxial film is grown on the wafer. If there are metal impurities or residual moisture in the memory of the reaction chamber, the manufactured epitaxial wafers will be contaminated by metal impurities, so the quality of the epitaxial wafers cannot be guaranteed.

Therefore, after performing the steps, the reaction chamber performs preventive maintenance (PM), so that residual moisture is generated in the reaction chamber after the PM. Residual moisture can be removed by steps such as baking the inside of the chamber.

In some embodiments, after placing the wafer on the susceptor inside the reaction chamber, the method further includes: heating the reaction chamber to a predetermined first temperature, and then stabilizing the reaction chamber. In this way, the reaction chamber can be baked, the moisture in the reaction chamber can be removed, and the temperature of various positions in the reaction chamber can be kept consistent, for example, the temperature of the lower part and the upper part of the base can be equalized.

In some embodiments, the first temperature may be 1100°C-1200°C. Specifically, the first temperature may be 1100°C, 1110°C, 1120°C, 1130°C, 1140°C, 1150°C, 1160°C, 1170°C, 1180°C, 1190°C or 1200°C c.

In this embodiment, the base can be stabilized by etching the surface of the base used to manufacture the epitaxial wafer and depositing a silicon film on the surface of the base.

The susceptor contains moisture as well as contaminants on the surface in contact with the wafer after the high temperature process, therefore, the susceptor surface needs to be stabilized to remove moisture, contaminants, metallic substances and various residues.

In this embodiment, the etching gas can be fed into the reaction chamber at the first temperature, the flow rate is 15SLM~20SLM, and the duration is 30s~40s, so as to remove moisture, pollutants, metal substances and various substances on the base. the remains. After that, the silicon source gas can be introduced into the reaction chamber at the second temperature, the flow rate is 20SLM~30SLM, and the duration is 40s~60s to form a silicon film with a certain thickness on the base, thereby making the base stable.

In some embodiments, the second temperature may be 1075°C-1175°C. Specifically, the second temperature may be 1075°C, 1085°C, 1095°C, 1105°C, 1115°C, 1125°C, 1135°C, 1145°C, 1155°C, 1165°C or 1175°C c.

In some embodiments, the silicon source gas may be trichlorosilane gas, and the etching gas may be HCL.

In some embodiments, measuring the MCLT of the epitaxial wafer after growing the epitaxial wafer further includes repeating the steps of removing the epitaxial wafer from the reaction chamber after manufacturing the epitaxial wafer and cleaning the reaction chamber until the MCLT reaches a predetermined value.

In some embodiments, the step of measuring the MCLT of the epitaxial wafer is performed during multiple runs, wherein the process of manufacturing one epitaxial wafer is referred to as a run. In this way, it can be judged whether the MCLT value of the epitaxial wafer reaches the set value.

In some embodiments, epitaxial wafers corresponding to 50, 100, 150, 200, 250, 300, 350, and 400 runs were taken as sample wafers and MCLT values were measured.

In some embodiments, when the MCLT reaches a predetermined value, the step of restarting the epitaxial growth equipment is completed.

After the sample wafer on which the epitaxial film was formed was removed from the reaction chamber, a step of removing the native oxide film by hydrofluoric acid treatment was performed. In addition, iodine was thinly deposited on the epitaxial wafer, and then the epitaxial wafer surface was scanned to measure the MCLT level.

Minority carrier lifetime (MCLT) can be a metric to determine readiness to restart an epitaxial growth system. MCLT refers to the average time required for the recombination of a large number of electrons, and the more impurities in the reaction chamber, the lower the MCLT.

Therefore, the MCLT of the sample wafers corresponding to 50, 100, 150, 200, 250, 300, 350, and 400 runs were measured, and when the MCLT satisfied the predetermined value, it could be determined that the preparation for restarting the epitaxial growth system was completed. When the MCLT value does not meet the predetermined value, continue to perform multiple operations.

In one embodiment, when the MCLT reaches a predetermined value, the restart program of the epitaxial growth system is completed, and the predetermined value can be set to 2800us, which means that almost all the pollutants such as metal particles in the reaction chamber are removed, It does not affect the quality of subsequent epitaxial wafers.

In a specific example, the method for restarting the epitaxial growth equipment includes the following steps: step S1, injecting hydrogen gas into the upper chamber and the lower chamber of the reaction chamber, and the duration is the entire process; step S2, placing the wafer in the reaction chamber On the base of the chamber, heat up the reaction chamber to raise the temperature to 1180°C; step S3, execute the step of baking the reaction chamber, set the baking temperature to 1180°C, and the duration is 65 seconds; step S4, execute the surface In the etching step, the etching gas HCL is introduced into the reaction chamber, the flow rate is 15SLM~20SLM, the duration is 30s~40s, and the temperature is set at 1180°C; step S5, the step of growing a thin film is performed, and the silicon source is introduced into the reaction chamber Gas TCS, the flow rate is 20SLM~30SLM, the duration is 40s~60s, and the temperature is set at 1125°C; step S6, making epitaxial wafers, the measurements correspond to 50, 100, 150, 200, 250, 300, 350 and 400 runs The MCLT value of the epitaxial wafer, if the MCLT value meets the set value, it can be considered that the recovery process of the epitaxial furnace is over. When the MCLT does not meet the set value, the process of S1-S6 needs to be repeated to ensure the required MCLT value when the epitaxy furnace is restarted.

FIG. 3 is a diagram showing the variation of the MCLT level inside the reaction chamber when the epitaxial furnace is being restarted in preparation for the related technology and the embodiment of the present invention. It can be seen that in related technologies, corresponding to 50 runs (Run), the MCLT value of the epitaxial wafer is less than 500us; corresponding to 100 runs, the MCLT value of the epitaxial wafer is less than 1500us; corresponding to 200 runs, the epitaxial wafer The MCLT value of the epitaxial wafer is about 1600us; corresponding to 250 operations, the MCLT value of the epitaxial wafer is less than 2000us; corresponding to 300 operations, the MCLT value of the epitaxial wafer is less than 2500us; corresponding to 350 operations, the MCLT value of the epitaxial wafer is approximately is 2700us; corresponding to 400 runs, the MCLT value of the epitaxial wafer is about 2800us. After adopting the technical solution of this embodiment, corresponding to 50 operations, the MCLT value of the epitaxial wafer is greater than 500us; corresponding to 100 operations, the MCLT value of the epitaxial wafer is greater than 2000us; corresponding to 200 operations, the MCLT value of the epitaxial wafer is greater than 2000us; The value is about 3000us; corresponding to 250 runs, the MCLT value of the epitaxial wafer is greater than 3000us; corresponding to 300 runs, the MCLT value of the epitaxial wafer is about 3100us.

Compared with the related technology, this embodiment can effectively shorten the time for the reaction chamber MCLT to reach the set value by designing the flow and time of the etching gas HCL and the silicon source gas TCS. If the above operations are not performed, the MCLT reaches about 2800us when the number of runs is about 400Run, and the epitaxy furnace reaches the condition of restarting at this time. However, if the above operations of this embodiment are performed, the MCLT can reach about 3000us at about 200Run times, which greatly shortens the restart time of the epitaxy furnace.

FIG. 4 shows the time and temperature required for each process each time an operation is completed when the epitaxial furnace is restarted in this embodiment. It can be seen that it takes about 330s to complete one operation in this embodiment, which can greatly shorten the restart time of the epitaxy furnace.

It should be noted that, in the present invention, the terms "comprising", "comprising" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a set of elements includes not only those elements , but also includes other elements not expressly listed, or also includes elements inherent in such a process, method, article, or device. Without further limitations, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes that element. In addition, it should be noted that the scope of the methods and apparatus in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved. Functions are performed, for example, the described methods may be performed in an order different from that described, and various steps may also be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative rather than restrictive. Under the enlightenment of the present invention, many forms can also be made without departing from the purpose of the present invention and the scope protected by the scope of the patent application, all of which belong to the protection of the present invention.

S101~S104: Step process 100: Epitaxy reaction equipment 101: air inlet 102: Air outlet 103: base

FIG. 1 shows a schematic flow diagram of a method for restarting epitaxial growth equipment according to an embodiment of the present invention; FIG. 2 shows a schematic structural diagram of an epitaxial growth device according to an embodiment of the present invention; Figure 3 shows a schematic diagram of MCLT changes in the reaction chamber when the epitaxial growth equipment is restarted; Fig. 4 shows a schematic diagram of the temperature and time of each process during each operation when the epitaxial growth equipment is restarted.

S101~S104: Step process

Claims (8)

A method for restarting epitaxial growth equipment, the steps comprising: injecting hydrogen gas into the reaction chamber set in the epitaxial growth equipment and purging the hydrogen gas for a predetermined time; placing a wafer on a pedestal inside the reaction chamber; Feed etching gas into the reaction chamber at the first temperature, the flow rate is 15SLM (Standard Liter/Minute, standard liter/minute) ~ 20SLM, and the duration is 30s (seconds) ~ 40s; Feed silicon source gas into the reaction chamber at the second temperature, the flow rate is 20SLM~30SLM, and the duration is 40s~60s; After the epitaxial wafer is grown, the minority carrier life time (MCLT) of the epitaxial wafer is measured, and when the MCLT reaches a predetermined value, the restart of the epitaxial growth equipment is completed. The method for restarting epitaxial growth equipment as described in Claim 1, wherein after the wafer is placed on the base inside the reaction chamber, the steps further include: The reaction chamber is heated to the predetermined first temperature, and then the reaction chamber is stabilized. The method for restarting epitaxial growth equipment according to claim 1 or 2, wherein the first temperature is 1100°C-1200°C. The method for restarting epitaxial growth equipment as described in Claim 1, wherein the second temperature is 1075°C-1175°C. The method for restarting epitaxial growth equipment as described in Claim 1, wherein the silicon source gas is trichlorosilane gas, and the etching gas is HCL (hydrochloric acid, hydrogen chloride). The method for restarting epitaxial growth equipment as claimed in claim 1, wherein measuring the MCLT of the epitaxial wafer after growing the epitaxial wafer further includes repeatedly performing the step of removing the epitaxial wafer from the reaction chamber after manufacturing the epitaxial wafer. wafer and clean the reaction chamber until the MCLT reaches a predetermined value. The method for restarting epitaxial growth equipment as described in Claim 1, wherein the step of measuring the MCLT of the epitaxial wafer is performed during multiple runs, wherein the process of manufacturing one epitaxial wafer is called one run. The epitaxial growth equipment restart method as described in claim 7, wherein the epitaxial wafers corresponding to 50, 100, 150, 200, 250, 300, 350 and 400 operations are taken as sample wafers and the MCLT value is measured.