A method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system

Abstract

The present invention provides a method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system, which relates to the technical field of semiconductor manufacturing. The method includes: growing an InGaAsP epitaxial layer at multiple growth temperatures; testing and determining each As component; using the functional relationship obtained by data fitting as the corresponding relationship between the growth temperature and the As component; growing an InGaAsP epitaxial layer on an InGaAs epitaxial layer at a first temperature; measuring the As component, and calculating the corresponding growth temperature according to the corresponding relationship as a second temperature; the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer = reference temperature - (second temperature - first temperature). Through the obtained corresponding relationship, the additional influence of the heat absorption of a specific thickness of InGaAs epitaxial layer on the growth temperature can be calculated, and based on this, the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer is determined, which is beneficial to improving the product quality.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and particularly to a method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system. Background Art

[0002] During the material growth process of molecular beam epitaxy (MBE), the growth temperature of the epitaxial layer is a key process parameter affecting the quality of the epitaxial product. Generally, the molecular beam epitaxy system heats the substrate holder through a holder heating device, and senses the temperature through a thermocouple arranged between the substrate holder and the holder heating device. The system acquires the sensed temperature and conducts heating control.

[0003] For the determination of the process parameters of a complex epitaxial layer structure, it is usually decomposed into multiple simple calibration structures. By growing the calibration structures, the optimal growth temperature (i.e., the corresponding thermocouple temperature) of the calibration structure is obtained, and this growth temperature is applied to the complete epitaxial structure. However, for the epitaxial layer growth on an InP substrate, when InGaAs material has been grown on the epitaxial layer, due to the small bandgap width of the InGaAs material, it will absorb a large amount of thermal radiation, causing the surface temperature of the epitaxial layer to rise. Since the thermocouple is located on the back of the substrate and is non-contact with the substrate, this increase in surface temperature is usually difficult to be accurately sensed quantitatively by the thermocouple and is difficult to be accurately fed back to the temperature control system, resulting in the inconsistency between the optimal temperature (thermocouple temperature) of other epitaxial layers determined based on the calibration structure and the optimal temperature when growing other epitaxial layers on the InGaAs epitaxial layer, which may lead to the deterioration of the epitaxial layer growth quality. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system, aiming at the deficiencies of the above-mentioned existing technologies, so as to solve the problem of determining the temperature for growing other epitaxial layers on the InGaAs epitaxial layer.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system. This method is used to determine the growth temperature when growing other epitaxial layers on an InGaAs epitaxial layer with a first preset thickness, and the method includes:

[0007] Step a, growing InGaAs epitaxial layers with a second preset thickness on an InP substrate at multiple different growth temperatures respectively to obtain multiple epitaxial wafers; y P 1-y epitaxial layer to obtain multiple epitaxial wafers;

[0008] Step b: Test the multiple epitaxial wafers respectively to determine the value of the As component y in each epitaxial wafer, so as to obtain a plurality of y values;

[0009] Step c: Perform data fitting on the multiple different growth temperatures and the multiple y values, and use the obtained functional relationship as the corresponding relationship between the growth temperature and the As component;

[0010] Step d: Continuously grow a second preset thickness of InGaAs y P 1-y epitaxial layer on the InGaAs epitaxial layer with the first preset thickness, and measure and determine the component y, where the InGaAs y P 1-y epitaxial layer has a growth temperature of the first temperature;

[0011] Step e: Calculate the growth temperature corresponding to the component y determined in step d in the corresponding relationship, and use the corresponding growth temperature as the second temperature;

[0012] Step f: The growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with the first preset thickness = reference temperature - (second temperature - first temperature), and the reference temperature is the growth temperature for growing other epitaxial layers on the InP substrate without the InGaAs epitaxial layer determined in advance.

[0013] Optionally, the other epitaxial layer includes one of the following: InP epitaxial layer, InGaAs epitaxial layer, InAlAs epitaxial layer, InGaAsP epitaxial layer.

[0014] Optionally, the InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with a fixed In component or a combined InGaAs epitaxial layer stacked by multiple InGaAs epitaxial layers with different In components.

[0015] Optionally, the range of the In component in the InGaAs epitaxial layer with the first preset thickness is greater than or equal to 0.4 and less than or equal to 0.55.

[0016] Optionally, the InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with an In component fixed at 0.53.

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

[0018] The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system provided by the present invention includes: Step a: Grow a second preset thickness of InGaAs on the InP substrate at multiple different growth temperatures y P 1-yAn epitaxial layer to obtain a plurality of epitaxial wafers; Step b: respectively test the plurality of epitaxial wafers to determine the value of the As component y in each epitaxial wafer, so as to obtain a plurality of y values; Step c: perform data fitting on the plurality of different growth temperatures and the plurality of y values, and use the obtained functional relationship as the corresponding relationship between the growth temperature and the As component; Step d: continue to grow an InGaAs epitaxial layer with a second preset thickness on the InGaAs epitaxial layer that has grown a first preset thickness y P 1-y epitaxial layer, and measure and determine the component y, where InGaAs y P 1-y The growth temperature of the epitaxial layer is the first temperature; Step e: calculate the growth temperature corresponding to the component y determined in Step d in the corresponding relationship, and use the corresponding growth temperature as the second temperature; Step f: The growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with a first preset thickness = reference temperature - (second temperature - first temperature), and the reference temperature is the growth temperature for growing other epitaxial layers on the InP substrate without an InGaAs epitaxial layer determined in advance. This method can calculate the additional influence of the heat absorption of the InGaAs epitaxial layer on the actual growth temperature by obtaining the corresponding relationship between the InGaAsP epitaxial layer component and the growth temperature, and then growing and measuring the component of InGaAsP on the InGaAs layer. Based on this, the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer can be determined, which is beneficial to improving product quality. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 The flowchart of the method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system provided by the embodiment of the present invention is shown. Detailed Embodiments

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0022] For the determination of process parameters of a complex epitaxial layer structure, it is usually decomposed into multiple simple calibration structures. By growing the calibration structures, the optimal growth temperature (i.e., the corresponding thermocouple temperature) of the calibration structure is obtained, and this growth temperature is applied to the complete epitaxial structure. However, for the epitaxial layer growth on an InP substrate, when InGaAs material has been grown on the epitaxial layer, due to the small bandgap width of the InGaAs material, it will absorb a large amount of thermal radiation, causing the surface temperature of the epitaxial layer to rise. Since the thermocouple is located on the back of the substrate and is non-contact with the substrate, this increase in surface temperature is usually difficult to be accurately sensed quantitatively by the thermocouple and is difficult to be accurately fed back to the temperature control system, resulting in the inconsistency between the optimal temperature (thermocouple temperature) of other epitaxial layers determined based on the calibration structure and the optimal temperature when growing other epitaxial layers on the InGaAs epitaxial layer, which may lead to the deterioration of the growth quality of the epitaxial layer. Therefore, a method for determining the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer is needed.

[0023] Figure 1 The flowchart of the method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system provided by the embodiment of the present invention is shown.

[0024] The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system provided by the present invention is used to determine the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with a first preset thickness, and the substrate used for growth is an InP substrate, as Figure 1 shown, the method includes:

[0025] Step a, growing InGaAs y P 1-y epitaxial layer with a second preset thickness on the InP substrate at multiple different growth temperatures to obtain multiple epitaxial wafers;

[0026] In the growth of step a, the component of In is a known component with a pre-calibrated and fixed value, so the temperature of the indium source furnace and the temperature of the gallium source furnace remain unchanged. And at the multiple different growth temperatures, the equivalent pressure of the As beam current and the equivalent pressure of the P beam current are both fixed. If the growth temperature remains unchanged, then due to the unchanged equivalent pressure of the As beam current and the equivalent pressure of the P beam current, the corresponding As component y will also be fixed. However, due to the change in the growth temperature, the desorption of As and P will be affected by the growth temperature, resulting in different As components y obtained at different temperatures. Generally speaking, the higher the growth temperature, the more serious the P desorption will be, and thus the higher the As component. It should be understood that in the multiple growths of step a, except for the different growth temperatures, other process parameters are the same. In step a, growing InGaAs y P 1-yThe epitaxial layer refers to InGaAs with a second preset thickness directly grown on an InP substrate. y P 1-y For the epitaxial layer, there is no other epitaxial layer structure grown between the InP substrate and the InGaAs y P 1-y epitaxial layer.

[0027] It should be noted that the growth temperature mentioned in this application refers to the thermocouple temperature sensed by the thermocouple set between the substrate pallet and the pallet heating device.

[0028] Step b: Test the multiple epitaxial wafers respectively to determine the value of the As component y in each epitaxial wafer, so as to obtain multiple y values.

[0029] Step c: Perform data fitting on the multiple different growth temperatures and the multiple y values, and use the obtained functional relationship as the corresponding relationship between the growth temperature and the As component.

[0030] Through steps a to c, the corresponding relationship between the growth temperature and the As component can be obtained.

[0031] Step d: Continuously grow an InGaAs epitaxial layer with a second preset thickness on the InGaAs epitaxial layer that has already grown a first preset thickness. y P 1-y For the epitaxial layer, and measure and determine the component y, where the growth temperature of the InGaAs y P 1-y epitaxial layer is the first temperature.

[0032] In step d, a first preset thickness of InGaAs epitaxial layer and a second preset thickness of InGaAs y P 1-y epitaxial layer can be continuously grown on the InP substrate. The first temperature here is the preset thermocouple temperature. Since the InGaAs epitaxial layer absorbs heat and causes the surface temperature of the epitaxial layer to rise, that is to say, when the thermocouple temperatures are all the first temperature, the actual growth temperature of the InGaAs y P 1-y epitaxial layer in step d is higher than the actual growth temperature of directly growing InGaAs y P 1-y epitaxial layer on the InP substrate, resulting in the actually obtained component y being higher than the expected value (that is, the component value when directly growing InGaAs y P 1-y epitaxial layer on the InP substrate).

[0033] It should be understood that in step d, when growing the second preset thickness of In x0 Ga 1-x0 Asy P 1-y During the process of growing the epitaxial layer, the temperature of the indium source furnace, the temperature of the gallium source furnace, the equivalent pressure of the As beam current, and the equivalent pressure of the P beam current are the same as those in step a.

[0034] Optionally, the InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with a fixed In composition or a combined InGaAs epitaxial layer stacked by multiple InGaAs epitaxial layers with different In compositions. The range of the In composition in the InGaAs epitaxial layer with the first preset thickness is greater than or equal to 0.4 and less than or equal to 0.55. Optionally, the InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with an In composition fixed at 0.53.

[0035] Step e: Calculate the growth temperature corresponding to the composition y determined in step d in the corresponding relationship, and use the corresponding growth temperature as the second temperature.

[0036] Using the corresponding relationship, the second temperature corresponding to the composition y determined in step d can be calculated. That is, growing InGaAs on the InGaAs layer with the first preset thickness at the first temperature y P 1-y has the same effect as directly growing InGaAs on the InP substrate at the second temperature. y P 1-y The effect of the epitaxial layer. Therefore, the endothermic contribution of the InGaAs layer with the first preset thickness is equivalent to the difference between the second temperature and the first temperature. The amount of heat absorbed by the InGaAs layer is usually closely related to the thickness of the InGaAs layer. The thicker the InGaAs layer, the greater the amount of heat absorbed.

[0037] Step f: The growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with the first preset thickness = reference temperature - (second temperature - first temperature), where the reference temperature is the pre-determined growth temperature for growing other epitaxial layers on the InP substrate without the InGaAs epitaxial layer. Optionally, the other epitaxial layers include one of the following: InP epitaxial layer, InGaAs epitaxial layer, InAlAs epitaxial layer, InGaAsP epitaxial layer.

[0038] The reference temperature can be the optimal temperature obtained when calibrating the growth of other epitaxial layers directly on the InP substrate. Similarly, the reference temperature here is also the thermocouple temperature. When growing other epitaxial layers on the InGaAs epitaxial layer with the first preset thickness, since the InGaAs epitaxial layer will absorb heat and cause the surface temperature of the epitaxial layer to rise, therefore, in order to offset the deviation of the actual growth temperature from the optimal growth temperature caused by this temperature rise, the reference temperature - (the second temperature - the first temperature) can be used as the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with the first preset thickness.

[0039] By obtaining the corresponding relationship between the InGaAsP epitaxial layer composition and the growth temperature, and then growing and measuring the composition of InGaAsP on the InGaAs layer, this method can calculate the additional influence of the heat absorption of the InGaAs epitaxial layer on the actual growth temperature. Based on this, the growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer can be determined, which is beneficial to improving the product quality.

[0040] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for determining the growth temperature of an epitaxial layer in a molecular beam epitaxy system, characterized in that, The method is used to determine the growth temperature when growing other epitaxial layers on an InGaAs epitaxial layer with a first preset thickness, and the method includes: Step a: Grow InGaAs with a second preset thickness on an InP substrate at multiple different growth temperatures respectively to obtain multiple epitaxial wafers. y P 1-y epitaxial layer Step b: Test the multiple epitaxial wafers respectively to determine the value of the As component y in each epitaxial wafer, so as to obtain multiple y values; Step c: Perform data fitting on the multiple different growth temperatures and the multiple y values, and use the obtained functional relationship as the corresponding relationship between the growth temperature and the As component; Step d: Continuously grow an InGaAs epitaxial layer with a second preset thickness on the InGaAs epitaxial layer that has grown to a first preset thickness, and measure and determine the composition y, where the growth temperature of the InGaAsP epitaxial layer is the first temperature; y P 1-y epitaxial layer, and measure and determine the composition y, where InGaAs y P 1-y epitaxial layer has a first temperature; Step e: Calculate the growth temperature corresponding to the component y determined in step d in the corresponding relationship, and use the corresponding growth temperature as the second temperature; Step f: The growth temperature when growing other epitaxial layers on the InGaAs epitaxial layer with the first preset thickness = reference temperature - (second temperature - first temperature), and the reference temperature is the growth temperature determined in advance for growing the other epitaxial layers on the InP substrate without the InGaAs epitaxial layer.

2. The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system according to claim 1, wherein The other epitaxial layer includes one of the following: InP epitaxial layer, InGaAs epitaxial layer, InAlAs epitaxial layer, InGaAsP epitaxial layer.

3. The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system according to claim 1, wherein The InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with a fixed In component or a combined InGaAs epitaxial layer stacked by multiple InGaAs epitaxial layers with different In components.

4. The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system according to claim 3, characterized in that, The range of the In component in the InGaAs epitaxial layer with the first preset thickness is greater than or equal to 0.4 and less than or equal to 0.

55.

5. The method for determining the growth temperature of the epitaxial layer in the molecular beam epitaxy system according to claim 4, wherein The InGaAs epitaxial layer with the first preset thickness is an InGaAs epitaxial layer with the In component fixed at 0.53.

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