A method for determining the residual amount of raw materials in the arsenic source furnace of a molecular beam epitaxy system

Abstract

The present invention provides a method for determining the remaining amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system, and relates to the field of semiconductor manufacturing technology. The method comprises: S1, by adjusting the heating power of the arsenic source furnace and stabilizing the preset time period, when the opening of the arsenic source furnace valve is the first preset opening, the measured arsenic beam current size is the first preset beam current; S2, under the power condition in S1, by adjusting the opening of the source furnace valve, the measured beam current size is the second preset beam current, and the opening of the arsenic source furnace valve at this time is recorded as the second measured opening; S3, when the second measured opening is less than or equal to the preset opening threshold, it is determined that the remaining amount of raw materials in the arsenic source furnace is insufficient, and an early warning reminder is issued. The present application can determine the insufficient state of raw materials based on the historical data of the raw materials of the arsenic source furnace combined with the current measurement data, and avoid starting subsequent growth when the raw materials are insufficient, thereby avoiding the scrapping of epitaxial wafers due to arsenic depletion during the growth process, saving costs.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a method for determining the residual amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system. Background Art

[0002] In the large-scale production of molecular beam epitaxy (MBE), for the epitaxial growth of III-V compounds, especially the growth of various epitaxial structures on GaAs substrates, arsenic molecular beams are almost always required, and arsenic molecular beams are usually oversupplied. Therefore, in molecular beam epitaxy, the consumption of arsenic raw materials in the arsenic source furnace is very large.

[0003] When the remaining raw materials in the arsenic source furnace are insufficient, if it is not discovered and warned in time, once the arsenic molecular beam is insufficient or completely exhausted during the epitaxial growth process, it will inevitably lead to the failure of this growth and the substrate material used will be scrapped, wasting not only the material but also the growth machine time.

[0004] Therefore, it is necessary to provide a method for determining the remaining amount of raw materials in the arsenic source furnace of a molecular beam epitaxy system, so that when the remaining amount of raw materials in the arsenic source furnace is insufficient, a determination can be made and an early warning can be issued to avoid starting the next epitaxial growth. Summary of the invention

[0005] The purpose of the present invention is to provide a method for determining the remaining amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system in view of the above-mentioned deficiencies in the prior art, so as to solve the problem of determining when the remaining amount of raw materials in the arsenic source furnace is insufficient.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for determining the residual amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system, the method comprising:

[0008] Step S1, by adjusting the heating power of the arsenic source furnace and stabilizing the preset time period, when the opening of the arsenic source furnace valve is a first preset opening, the measured arsenic beam current size is the first preset beam current;

[0009] Step S2, under the heating power condition in step S1, by adjusting the opening of the arsenic source furnace valve, the measured arsenic beam current is equal to the second preset beam current, and the opening of the arsenic source furnace valve at this time is recorded as the second measured opening, and the second preset beam current is smaller than the first preset beam current;

[0010] Step S3, when the second measured opening is less than or equal to the preset opening threshold, it is determined that the raw material remaining in the arsenic source furnace is insufficient, and an early warning reminder is issued. The preset opening threshold is that in the same molecular beam epitaxy system, during the historical use process before the current raw material is loaded into the arsenic source furnace, when the raw material remaining in the arsenic source furnace is greater than zero and equal to or less than the preset remaining threshold, the opening corresponding to the second preset beam current measured by steps S1 and S2 is adopted. The preset remaining threshold is the amount of arsenic required to grow an arsenide epitaxial material of a preset thickness before the arsenic raw material in the arsenic source furnace is completely exhausted.

[0011] Optionally, the preset aperture threshold is obtained in the following manner: in the same molecular beam epitaxy system, in the historical use process before the current raw material is loaded into the arsenic source furnace, the entire process from the loading of the arsenic raw material into the arsenic source furnace to the complete exhaustion of the loaded arsenic raw material is planned according to the preset measurement time points, and at each measurement time point, respectively, a second measurement aperture corresponding to the arsenic beam current size being a second preset beam current is measured according to step S1 and step S2, and a second measurement aperture data set is formed by the measured second measurement aperture and the corresponding measurement time point, and starting from the time when the arsenic raw material is completely exhausted, based on the molecular beam epitaxial growth record, a time point before the last preset thickness of arsenide epitaxial material is grown using the remaining arsenic raw material before exhaustion is calculated backwards, and the second measurement aperture obtained by the first measurement in the time period after the calculated time point and before the arsenic raw material is completely exhausted is selected from the second measurement aperture data set as the preset aperture threshold.

[0012] Optionally, the preset thickness ranges from greater than or equal to 1 micrometer to less than 5 micrometers.

[0013] Optionally, the value range of the first preset beam current is greater than or equal to 1×10 -5 Torr, the value range of the second preset beam current is less than or equal to 3×10 -6 Torr.

[0014] Optionally, the value range of the first preset beam current is greater than or equal to 1.2×10 -5 Torr, the value range of the second preset beam current is less than or equal to 2×10 -6 Torr.

[0015] Optionally, the first preset opening degree is greater than or equal to 50% and less than or equal to 98%.

[0016] Optionally, the first preset opening degree is greater than or equal to 70% and less than or equal to 90%.

[0017] The beneficial effects of the present invention include:

[0018] The method for determining the residual amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system provided by the present invention comprises: step S1, adjusting the heating power of the arsenic source furnace and stabilizing the preset time period so that when the opening of the valve of the arsenic source furnace is a first preset opening, the measured arsenic beam current size is the first preset beam current; step S2, under the heating power condition in step S1, adjusting the opening of the valve of the arsenic source furnace so that the measured arsenic beam current size is a second preset beam current, and recording the opening of the valve of the arsenic source furnace at this time as the second measured opening, and the second preset beam current is less than the first preset beam current; step S 3. When the second measured opening is less than or equal to the preset opening threshold, it is determined that the raw material remaining in the arsenic source furnace is insufficient, and an early warning reminder is issued. The preset opening threshold is that in the same molecular beam epitaxy system, during the historical use process before the current raw material is loaded into the arsenic source furnace, when the raw material remaining in the arsenic source furnace is greater than zero and equal to or less than the preset remaining threshold, the opening corresponding to the second preset beam current measured by steps S1 and S2 is obtained. The preset remaining threshold is the amount of arsenic required to grow arsenide epitaxial material of a preset thickness before the arsenic raw material in the arsenic source furnace is completely exhausted. The present application adjusts the power of the arsenic source furnace by limiting the first preset beam current and the first preset opening, and then obtains the measured opening of the smaller second preset beam current under the power. When there is less raw material in the arsenic source furnace, in order to maintain a large stable beam current, the heating power needs to be increased. The high heating power will cause the opening corresponding to the small beam current to decrease. Therefore, based on the historical usage data of the raw materials of the arsenic source furnace combined with the current measurement data, the raw material shortage state can be determined, and an early warning reminder can be issued when the raw materials are insufficient to avoid starting subsequent growth, thereby avoiding the scrapping of epitaxial wafers due to arsenic depletion during the growth process, thereby saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The flowchart of the method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system provided by the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the large-scale production of molecular beam epitaxy (MBE), for the epitaxial growth of III-V compounds, especially the growth of various epitaxial structures on gallium arsenide substrates, arsenic molecular beams are almost always required, and arsenic molecular beams are usually oversupplied. Therefore, in molecular beam epitaxy, the consumption of arsenic raw materials in the arsenic source furnace is very large. When the remaining raw materials in the arsenic source furnace are insufficient, if it is not discovered and warned in time, once the arsenic molecular beam is insufficient or completely exhausted during the epitaxial growth process, it will inevitably lead to the failure of this growth, and the substrate material used will be scrapped, wasting materials and growth time. Therefore, it is necessary to provide a method for determining the remaining raw materials in the arsenic source furnace of a molecular beam epitaxy system, so that it can be determined and warned when the remaining raw materials in the arsenic source furnace are insufficient, so as to avoid starting the next epitaxial growth.

[0023] Figure 1 FIG. 1 is a flow chart showing a method for determining the residual amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system provided by an embodiment of the present invention. Figure 1 As shown, the method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system provided by the present invention comprises:

[0024] Step S1, by adjusting the heating power of the arsenic source furnace and stabilizing it for a preset time period, when the opening of the arsenic source furnace valve is a first preset opening, the measured arsenic beam current size is the first preset beam current.

[0025] Generally, when the heating power of the arsenic source furnace is constant, the larger the opening of the arsenic source furnace valve, the larger the corresponding arsenic beam. When the opening of the arsenic source furnace valve is constant, the larger the heating power of the arsenic source furnace, the larger the arsenic beam. Therefore, when the opening is the first preset opening, the arsenic beam size can be achieved by adjusting the heating power of the arsenic source furnace and stabilizing the preset time period. When the heating power of the arsenic source furnace is adjusted and the arsenic beam size corresponding to the first preset opening is the first preset beam, the heating power is fixed. In step S2, the heating power is stable and unchanged. During normal operation, step S2 will be performed immediately after step S1 is completed. The opening of the arsenic source furnace valve refers to the degree of valve opening. The theoretical maximum opening of the arsenic source furnace valve is 100%. Optionally, the first preset opening is greater than or equal to 50%, and less than or equal to 98%. Preferably, the first preset opening is greater than or equal to 70%, and less than or equal to 90%.

[0026] Step S2, under the heating power condition in step S1, by adjusting the opening of the arsenic source furnace valve, the measured arsenic beam current size is made to be the second preset beam current, and the opening of the arsenic source furnace valve at this time is recorded as the second measured opening.

[0027] The second preset beam current is smaller than the first preset beam current.

[0028] It should be noted that the first preset beam current, the second preset beam current and the first preset opening are all predetermined values, and the second measured opening is a measured value actually measured in step S2.

[0029] The more the second preset beam current differs from the first preset beam current, the more sensitive the second measurement opening is to the reduction of raw materials. This is because, when there are more raw materials in the arsenic source furnace, when the heating power of the arsenic source furnace is stable, whether it is the larger first preset beam current or the smaller second preset beam current, the corresponding valve opening of the arsenic source furnace is relatively stable. With the consumption of the raw materials in the arsenic source furnace, the remaining raw materials in the arsenic source furnace gradually decrease. When the heating power of the arsenic source furnace is stable, the valve openings corresponding to the first preset beam current and the second preset beam current are increasing. In other words, when the heating power remains unchanged, as the arsenic raw material decreases, the valve opening needs to be gradually increased to maintain a constant beam current. Of course, this change in valve opening is very slow. Since there is an upper limit to the valve opening, as the arsenic raw material decreases, the conventional practice is to gradually increase the heating power of the arsenic source furnace to maintain the relative stability of the valve opening of the arsenic source furnace and the corresponding beam current. Similarly, when the arsenic raw material is not very small, the change in heating power is also very slow, and it is almost unchanged in a short time (usually several days). In the case where the arsenic raw material is not very small, by increasing the heating power of the arsenic source furnace, the corresponding valve openings are relatively stable for the larger first preset beam current and the smaller second preset beam current. However, when the raw material in the arsenic source furnace is very small, as the arsenic raw material is used, in order to maintain a stable and larger first preset beam current, the heating power of the arsenic source furnace increases rapidly. This faster increase in heating power causes the arsenic pressure in the arsenic source furnace to be higher than the arsenic pressure when the raw material is more. In this case, for the smaller second preset beam current, relative to the second measurement opening in the case of more raw materials, only a smaller opening is required to obtain the second preset beam current. The more the second preset beam current differs from the first preset beam current (in other words, the smaller the value of the second preset beam current is when the first preset beam current is stable and unchanged), when the heating power is increased to maintain the first preset beam current when the raw material in the arsenic source furnace is very small, the second measurement opening decreases more significantly relative to the conventional value (the second measurement opening in the case of more raw materials). Therefore, when there is very little raw material in the arsenic source furnace, the shortage of arsenic raw material can be determined based on historical test data and changes in the second measured opening value, and an early warning reminder can be given when the arsenic raw material is insufficient to avoid unnecessary losses caused by subsequent startup growth.

[0030] In the growth process of conventional molecular beam epitaxy materials, different material layers or different growth rates require different arsenic beam sizes. In this application, the maximum arsenic beam size required for conventional epitaxial material growth can be used as the first preset beam. The arsenic beam used in the substrate material stripping stage is much smaller than the arsenic beam required for material growth. Therefore, in this application, the arsenic beam used in the substrate material stripping stage can be used as the second preset beam. Optionally, the value range of the first preset beam is greater than or equal to 1×10 -5 Torr, the value range of the second preset beam current is less than or equal to 3×10 -6 Preferably, the value range of the first preset beam current is greater than or equal to 1.2×10 -5 Torr, the value range of the second preset beam current is less than or equal to 2×10 -6 Torr.

[0031] Step S3: when the second measured opening is less than or equal to the preset opening threshold, it is determined that the remaining amount of raw materials in the arsenic source furnace is insufficient, and an early warning reminder is issued.

[0032] The preset opening threshold is, in the same molecular beam epitaxy system, during the historical use process before the current raw material is loaded into the arsenic source furnace, when the raw material balance in the arsenic source furnace is greater than zero and equal to or less than the preset balance threshold, the opening corresponding to the second preset beam current measured by steps S1 and S2. The preset balance threshold is the amount of arsenic required to grow an arsenide epitaxial material of a preset thickness before the arsenic raw material in the arsenic source furnace is completely exhausted.

[0033] Arsenide epitaxial materials include all epitaxial materials that require an arsenic molecular beam for epitaxial growth in a molecular beam epitaxy system, such as gallium arsenide materials, aluminum gallium arsenide materials, indium gallium arsenide materials, and the like.

[0034] In practical applications, the arsenic source furnace is reused. When the arsenic raw materials in the arsenic source furnace are used up (exhausted), new raw materials can be reloaded into the arsenic source furnace during the subsequent maintenance and upkeep of the molecular beam epitaxy system. The historical use process of the arsenic source furnace refers to the entire process from the loading of raw materials into the arsenic source furnace to the exhaustion of the loaded raw materials. The current raw materials loaded in the arsenic source furnace refer to the raw materials currently in use.

[0035] Optionally, the preset aperture threshold is obtained in the following manner: in the same molecular beam epitaxy system, in the historical use process before the current raw material is loaded into the arsenic source furnace, the entire process from the loading of the arsenic raw material into the arsenic source furnace to the complete exhaustion of the loaded arsenic raw material is planned according to the preset measurement time points, and at each measurement time point, respectively, a second measurement aperture corresponding to the arsenic beam current size being a second preset beam current is measured according to step S1 and step S2, and a second measurement aperture data set is formed by the measured second measurement aperture and the corresponding measurement time point, and starting from the time when the arsenic raw material is completely exhausted, based on the molecular beam epitaxial growth record, a time point before the last preset thickness of arsenide epitaxial material is grown using the remaining arsenic raw material before exhaustion is calculated backwards, and the second measurement aperture obtained by the first measurement in the time period after the calculated time point and before the arsenic raw material is completely exhausted is selected from the second measurement aperture data set as the preset aperture threshold.

[0036] The molecular beam epitaxy growth record is various data recorded during the conventional growth of molecular beam epitaxy, including but not limited to information related to epitaxial growth such as growth time, growth material, growth structure, growth rate, growth thickness, and process parameters. Optionally, the range of the preset thickness is greater than or equal to 1 micron and less than 5 microns. Preferably, the range of the preset thickness is greater than or equal to 1 micron and less than 3 microns. Taking the preset thickness of 2 microns as an example, for example, the arsenic raw material is exhausted at 15:00 p.m. on the 13th of a certain month of a certain year. According to the molecular beam epitaxy growth record, it is reversed from 15:00 p.m. on the 13th of the month. The result is calculated that the total thickness of the arsenide epitaxial material epitaxially grown from 16:00 p.m. on the 11th of the month to 15:00 p.m. on the 13th of the month is 2 microns. Then 16:00 p.m. on the 11th of the month is taken as the calculated time point, and the second measurement aperture obtained by the first measurement in the time period between 16:00 p.m. on the 11th of the month and 15:00 p.m. on the 13th of the month is selected from the second measurement aperture data set as the preset aperture threshold. It should be understood that when using an arsenic molecular beam, arsenic depletion can be easily and promptly detected based on real-time data of the growth chamber ion gauge or real-time data of the background vacuum.

[0037] The preset measurement time point planning can be determined according to the daily arsenic usage, for example, it can be measured once a week, once every three days, or once a day. In a period of time after the arsenic source furnace is just filled with raw materials, the arsenic raw materials are sufficient and the arsenic beam is relatively stable, so the measurement time interval can be longer. After the arsenic source furnace has been used for a certain period of time, the measurement time interval can be appropriately reduced.

[0038] As mentioned above, the maximum arsenic beam size required for the growth of conventional epitaxial materials is used as the first preset beam, and the arsenic beam used in the substrate material stripping stage is used as the second preset beam. In the large-scale production of molecular beam epitaxy, the measurement of the arsenic beam used daily is a regular routine operation. Usually, the above two beams are measured each time, and the heating power is gradually increased according to the consumption of arsenic raw materials to maintain the relative stability of the beam and the opening. Therefore, using the method proposed in the present application, in the daily operation of molecular beam epitaxy growth, it is only necessary to standardize the daily beam measurement process according to the requirements in step S1 and step S2, so that the daily arsenic beam measurement data, growth record data and historical usage data can be used to determine and warn when the raw material surplus in the arsenic source furnace is insufficient.

[0039] In summary, the present application adjusts the power of the arsenic source furnace by limiting the first preset beam current and the first preset opening, and then obtains the measured opening of the smaller second preset beam current under this power. When there is less raw material in the arsenic source furnace, in order to maintain a large stable beam current, it is necessary to increase the heating power. The high heating power will cause the opening corresponding to the small beam current to decrease. Therefore, based on the historical usage data of the raw materials of the arsenic source furnace combined with the current measurement data, the raw material shortage state can be determined, and an early warning reminder can be issued when the raw materials are insufficient to avoid starting subsequent growth, thereby avoiding the scrapping of epitaxial wafers due to arsenic depletion during the growth process, thereby saving production costs.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the residual amount of raw materials in an arsenic source furnace of a molecular beam epitaxy system, characterized in that: The method comprises: Step S1, by adjusting the heating power of the arsenic source furnace and stabilizing the preset time period, when the opening of the arsenic source furnace valve is a first preset opening, the measured arsenic beam current size is the first preset beam current; Step S2, under the heating power condition in step S1, by adjusting the opening of the arsenic source furnace valve, the measured arsenic beam current is a second preset beam current, and the opening of the arsenic source furnace valve at this time is recorded as a second measured opening, and the second preset beam current is smaller than the first preset beam current; Step S3, when the second measured opening is less than or equal to a preset opening threshold, it is determined that the remaining amount of raw materials in the arsenic source furnace is insufficient, and an early warning reminder is issued, the preset opening threshold is, in the same molecular beam epitaxy system, in the historical use process before the current raw material is loaded into the arsenic source furnace, when the remaining amount of raw materials in the arsenic source furnace is greater than zero and equal to or less than the preset remaining threshold, the opening corresponding to the second preset beam current measured by step S1 and step S2 is used, the preset remaining threshold is the amount of arsenic required to grow an arsenide epitaxial material of a preset thickness before the arsenic raw material in the arsenic source furnace is completely exhausted, The preset opening threshold is obtained in the following manner: in the same molecular beam epitaxy system, in the historical use process before the current raw material is loaded into the arsenic source furnace, the entire process from the loading of the arsenic source furnace with the arsenic raw material to the complete exhaustion of the loaded arsenic raw material is planned according to the preset measurement time points, and at each measurement time point, the second measurement opening corresponding to the arsenic beam current size being the second preset beam current is measured according to step S1 and step S2, and a second measurement opening data set is formed by the measured second measurement opening and the corresponding measurement time point, starting from the time when the arsenic raw material is completely exhausted, according to the molecular beam epitaxial growth record, the time point before the last preset thickness of the arsenide epitaxial material is grown by using the remaining arsenic raw material before exhaustion is reversely calculated, and the second measurement opening obtained by the first measurement in the time period after the calculated time point and before the arsenic raw material is completely exhausted is selected from the second measurement opening data set as the preset opening threshold, The value range of the first preset beam current is greater than or equal to 1×10 -5 Torr, the value range of the second preset beam current is less than or equal to 3×10 -6 Torr.

2. The method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system according to claim 1, characterized in that: The preset thickness ranges from greater than or equal to 1 micron to less than 5 microns.

3. The method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system according to claim 1, characterized in that: The value range of the first preset beam current is greater than or equal to 1.2×10 -5 Torr, the value range of the second preset beam current is less than or equal to 2×10 -6 Torr.

4. The method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system according to claim 1 or 3, characterized in that: The first preset opening degree is greater than or equal to 50% and less than or equal to 98%.

5. The method for determining the residual amount of raw materials in the arsenic source furnace of the molecular beam epitaxy system according to claim 4, characterized in that: The first preset opening degree is greater than or equal to 70% and less than or equal to 90%.

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