A method for regrowth of epitaxial layer of semiconductor structure

Abstract

The present invention relates to a method for regrowth of an epitaxial layer of a semiconductor structure, comprising: providing an etched semiconductor structure; preparing a self-assembled organic solution; placing the etched semiconductor structure in the self-assembled organic solution, the self-assembled organic solution forming a self-assembled monolayer film on the surface of the semiconductor structure, the self-assembled monolayer film serving as a passivation film; placing the semiconductor structure formed with the self-assembled monolayer film in a growth device, heating it to a first temperature to remove the self-assembled monolayer film; the first temperature is the decomposition temperature of the self-assembled monolayer film; heating it to a second temperature to regrow on the surface of the semiconductor structure to form an epitaxial layer; the second temperature is the growth temperature of the epitaxial layer. The method for regrowth of an epitaxial layer of a semiconductor structure provided by the present invention can ensure that no oxide layer is generated before the epitaxial layer is formed on the surface of the semiconductor structure, improve the interface quality between the epitaxial layer and the semiconductor structure, improve the quality and efficiency of the growth of the epitaxial layer, and thus improve the electrical and optical properties of the device finally formed.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a regrowth method for an epitaxial layer of a semiconductor structure. Background Art

[0002] III-V semiconductor materials, such as gallium arsenide (GaAs) and indium phosphide (InP), are widely used in microelectronics and optoelectronics due to their unique electronic properties, such as high-speed transistors, optoelectronic devices, solar cells, etc. However, a common feature of these materials is that they are easily oxidized, especially when exposed to air or moisture, and they quickly form a "native oxide" (natural oxide layer). This oxide layer not only affects the electrical properties of the material, resulting in a decrease in product performance, but may also cause device reliability issues, accelerate device aging, and reduce the life and stability of the device.

[0003] In particular, some high-end chips such as electro-absorption modulated lasers (EML) usually integrate multiple functional devices into one chip, which requires multiple etchings on the wafer and then multiple epitaxial regrowths. Usually after etching, some key parts of the device will be exposed, such as multi-layer quantum well structures, and some materials that are very easy to oxidize, such as components containing aluminum (Al). If the oxide layer on the surface of these materials is not removed before regrowth, the oxide layer will become an obstacle in the epitaxial growth process, resulting in a decrease in the interface quality between the newly grown semiconductor layer and the substrate material, and interface defects, stress and lattice mismatch may occur, seriously affecting the electrical and optical properties of the material.

[0004] Therefore, a method for regrowth of an epitaxial layer of a semiconductor structure is needed, which can form a passivation layer on the surface of the semiconductor structure to ensure that no oxide layer is generated on the surface of the semiconductor structure before the epitaxial layer is formed, thereby improving the interface quality between the epitaxial layer and the semiconductor structure, improving the quality and efficiency of the epitaxial layer growth, and further improving the electrical and optical properties of the finally formed device. Summary of the invention

[0005] Therefore, the present invention provides a method for regrowth of an epitaxial layer of a semiconductor structure to solve the problem in the prior art that an oxide layer is easily generated on the surface of a semiconductor structure of group III-V materials, which becomes an obstacle in the epitaxial regrowth process, resulting in a decrease in the interface quality between the regrowth epitaxial layer and the semiconductor structure, the occurrence of interface defects, stress and lattice mismatch, and seriously affecting the electrical and optical properties of the material.

[0006] The present invention provides a method for regrowth of an epitaxial layer of a semiconductor structure, comprising:

[0007] Providing an etched semiconductor structure;

[0008] preparing a self-assembling organic solution;

[0009] placing the etched semiconductor structure into the self-assembled organic solution, wherein the self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure, and the self-assembled monolayer film serves as a passivation film;

[0010] Putting the semiconductor structure formed with the self-assembled monolayer film into a growth device, and heating it to a first temperature to remove the self-assembled monolayer film; the first temperature is the decomposition temperature of the self-assembled monolayer film;

[0011] The semiconductor structure is heated to a second temperature to re-grow an epitaxial layer on the surface of the semiconductor structure; the second temperature is the growth temperature of the epitaxial layer.

[0012] Optionally, the second temperature is greater than the first temperature.

[0013] Optionally, the thickness of the self-assembled monolayer is 2nm~3nm.

[0014] Optionally, the first temperature is 150°C to 300°C;

[0015] The second temperature is 550°C to 800°C;

[0016] The step of heating to a first temperature to remove the self-assembled monolayer film includes a heating stage and a constant temperature stage, and the duration of the constant temperature stage is a first duration; the first duration is 10 minutes to 20 minutes.

[0017] Optionally, before the step of placing the etched semiconductor structure into the self-assembling organic solution, the step further includes:

[0018] Cleaning the semiconductor structure to remove oxide on the surface of the semiconductor structure;

[0019] placing the cleaned semiconductor structure into a first ammonia solution for temporary storage;

[0020] The 30% ammonia solution and H 2 Volume ratio of O: 30% ammonia solution: H 2 O = 1:9~1:25;

[0021] The temporary storage time is less than 10 minutes.

[0022] Optionally, the step of placing the etched semiconductor structure into the self-assembling organic solution includes:

[0023] The semiconductor structure is taken out from the ammonia solution and placed in the self-assembly organic solution within less than 10 seconds.

[0024] Optionally, after the step of forming a self-assembled monolayer film on the surface of the semiconductor structure, the method further comprises:

[0025] The semiconductor structure is removed from the nitrogen atmosphere and dried.

[0026] Optionally, the step of placing the semiconductor structure formed with the self-assembled monolayer film into a growth device, heating it to a first temperature and removing the self-assembled monolayer film further includes:

[0027] Hydrogen is passed through the surface of the semiconductor structure to remove byproducts produced during the self-assembled monolayer film process.

[0028] Optionally, the material of the semiconductor structure is a III-V compound material;

[0029] The material of the self-assembled monolayer film is an organic compound containing thiol groups.

[0030] Optionally, the III-V compound material includes GaAs, InP, InAs, InGaAs or GaN;

[0031] The material of the self-assembled monolayer film is alkylthiol or 3-mercaptopropyltrimethoxysilane.

[0032] Optionally, the material of the semiconductor structure is GaAs; the material of the self-assembled monolayer film is alkylthiol;

[0033] The step of preparing the self-assembling organic solution comprises:

[0034] Mixing anhydrous ethanol and alkyl mercaptan evenly to obtain a first solution;

[0035] Adding a second ammonia solution with a concentration of 30% to the first solution to obtain an alkylthiol solution; in the alkylthiol solution, the volume ratio of the second ammonia solution to the first solution is 2% to 10%;

[0036] A degassing treatment is performed to remove oxygen in the alkyl mercaptan solution.

[0037] Optionally, during the process of forming the self-assembled monolayer film on the surface of the semiconductor structure, the temperature of the self-assembled organic solution is 30° C. to 50° C., and the formation time of the self-assembled monolayer film is 30 mins to 50 mins.

[0038] The technical solution of the present invention has the following advantages:

[0039] (1) The method for regrowth of an epitaxial layer of a semiconductor structure provided by the present invention, on the one hand, uses a self-assembled monolayer film as a passivation film on the surface of the semiconductor structure after etching, which can ensure that the semiconductor structure does not contact the air during the process from etching to epitaxial regrowth, effectively inhibits the occurrence of oxidation, ensures that no oxide layer is generated on the surface of the semiconductor structure before the epitaxial layer is formed, and achieves effective protection of the semiconductor structure; on the other hand, the thickness of the self-assembled monolayer film is nanometer-level, and it is easy to decompose at high temperature, so the self-assembled monolayer film can be removed by heating before the epitaxial layer is formed, and no damage will be caused to the surface of the semiconductor structure, and the product after the decomposition of the self-assembled monolayer film will not cause any pollution to the wafer and the equipment. Therefore, the method for regrowth of an epitaxial layer of a semiconductor structure provided by the present invention uses a self-assembled monolayer film as a passivation film on the surface of the semiconductor structure after etching, which can ensure that no oxide layer is generated on the surface of the semiconductor structure before the epitaxial layer is formed, can improve the interface quality between the epitaxial layer and the semiconductor structure, improve the quality and efficiency of the epitaxial layer growth, and thus improve the electrical and optical properties of the device finally formed, and prevent the performance degradation and aging of the device caused by oxidation.

[0040] (2) The present invention provides a method for regrowth of an epitaxial layer of a semiconductor structure. The second temperature for regrowth to form an epitaxial layer is greater than the first temperature for removing the self-assembled monolayer. The self-assembled monolayer can be first heated to the first temperature in the growth device to remove the self-assembled monolayer, and then heated to the second temperature to regrow the epitaxial layer on the surface of the semiconductor structure. No additional equipment and process are required to remove the self-assembled monolayer, and it is also ensured that no oxide layer is generated on the surface of the semiconductor structure before the epitaxial layer is formed. The protective effect of the passivation layer on the surface of the semiconductor structure can be improved, and the process flow can be simplified. In addition, the second temperature is greater than the first temperature, and the residue of the self-assembled monolayer can be further removed during the heating process of epitaxial growth to ensure complete removal.

[0041] (3) The method for regrowth of an epitaxial layer of a semiconductor structure provided by the present invention comprises the following steps: after removing the oxide on the surface of the etched semiconductor structure and before forming a self-assembled monolayer film, the cleaned semiconductor structure is temporarily placed in a first ammonia solution for less than 10 minutes; in a nitrogen atmosphere, the semiconductor structure is taken out of the first ammonia solution and placed in a self-assembled organic solution for less than 10 seconds, wherein the self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure, thereby ensuring that the semiconductor structure is not exposed to air during the process from etching to forming the self-assembled monolayer film, thereby effectively inhibiting oxidation, while having no effect on the semiconductor structure and not affecting production capacity.

[0042] (4) In the method for regrowth of an epitaxial layer of a semiconductor structure provided by the present invention, hydrogen is passed through the surface of the semiconductor structure when heating to remove the self-assembled monolayer film. The hydrogen can be used to easily remove the by-products of the self-assembled monolayer film process, so that the self-assembled monolayer film is completely removed without remaining on the semiconductor surface or causing any damage to the surface of the semiconductor structure. Furthermore, the products after decomposition of the self-assembled monolayer film will not cause any pollution to the wafer and the equipment, thereby improving the interface quality between the epitaxial layer and the semiconductor structure and improving the quality and efficiency of the epitaxial layer growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A schematic flow chart of a method for regrowth of an epitaxial layer of a semiconductor structure according to an embodiment of the present invention;

[0045] Figure 2 The present invention is a schematic diagram of a specific process of a method for regrowth of an epitaxial layer of a semiconductor structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In the prior art, some surface cleaning or surface passivation methods are usually adopted. Before epitaxial regrowth, chemical cleaning or plasma cleaning technology is used to remove the surface oxide layer of the semiconductor structure to ensure the cleanliness of the material surface. However, the surface of the wafer after cleaning will be oxidized immediately after being exposed to the air. Even if the time interval is very short, the oxidation of the material surface cannot be completely avoided. The passivation layer usually adopts an oxide or nitride dielectric film. These passivation layers must be cleaned before epitaxial growth, and this process must occur in the epitaxial growth cavity (in-situ cleaning). The stability of oxides and nitrides under high temperature makes it difficult to be completely removed, and it will inevitably cause contamination of the epitaxial growth chamber, resulting in an increase in process complexity and a decrease in product stability.

[0047] In order to solve the problem in the prior art that an oxide layer is easily generated on the surface of a semiconductor structure of group III-V materials, which becomes an obstacle in the epitaxial regrowth process, causes the interface quality between the regrowth epitaxial layer and the semiconductor structure to deteriorate, and causes interface defects, stress and lattice mismatch, which seriously affect the electrical and optical properties of the material, the present invention provides a method for regrowth of an epitaxial layer of a semiconductor structure, comprising: providing an etched semiconductor structure; preparing a self-assembled organic solution; placing the etched semiconductor structure into the self-assembled organic solution, wherein the self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure, and the self-assembled monolayer film serves as a passivation film; placing the semiconductor structure formed with the self-assembled monolayer film into a growth device, and heating it to a first temperature to remove the self-assembled monolayer film; the first temperature is the decomposition temperature of the self-assembled monolayer film; heating it to a second temperature to regrow on the surface of the semiconductor structure to form an epitaxial layer; the second temperature is the growth temperature of the epitaxial layer.

[0048] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0049] Example 1

[0050] like Figure 1 As shown, this embodiment provides a method for regrowth of an epitaxial layer of a semiconductor structure, comprising:

[0051] S101, providing an etched semiconductor structure;

[0052] S102, preparing a self-assembling organic solution;

[0053] S103, placing the etched semiconductor structure into the self-assembled organic solution, wherein the self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure, and the self-assembled monolayer film serves as a passivation film;

[0054] S104, placing the semiconductor structure formed with the self-assembled monolayer film into a growth device, and heating it to a first temperature to remove the self-assembled monolayer film; the first temperature is the decomposition temperature of the self-assembled monolayer film;

[0055] S105, heating to a second temperature to re-grow an epitaxial layer on the surface of the semiconductor structure; the second temperature is the growth temperature of the epitaxial layer.

[0056] In specific implementation, the self-assembled monolayer film has extremely high stability, which can ensure that the semiconductor structure will not be oxidized after at least one day, and even has the effect of inhibiting oxidation after two weeks. During this period, some detection and characterization work can be carried out.

[0057] The first temperature is the decomposition temperature of the self-assembled monolayer. When the temperature of the self-assembled monolayer is greater than the first temperature (generally 150°C to 300°C), the self-assembled monolayer will begin to decompose. Since the self-assembled monolayer is very thin, only 2-3 nm, the decomposition products are easily carried away by the gas and will not cause any pollution to the wafer and equipment.

[0058] The second temperature is the growth temperature of the epitaxial layer. When the temperature of the growth equipment is greater than the second temperature, an epitaxial layer can be grown again on the semiconductor structure. The epitaxial layer can be GaAs, InP, GaN, AlAs, etc., or an epitaxial layer of other materials, which is not limited in this embodiment. The growth temperatures of different epitaxial layers are different. For example, the growth temperature of GaAs metal organic chemical vapor deposition (MOCVD) is 600ºC~750ºC; the growth temperature of InP MOCVD is 550ºC~700ºC; the growth temperature of GaN molecular beam epitaxy (MBE) is 600ºC~800ºC, etc.

[0059] Self-assembled monolayers (SAMs) are thermodynamically stable, highly oriented, tightly packed monolayer ordered molecular films formed by spontaneous adsorption of organic functional molecules on liquid-solid or gas-solid interfaces through chemical bonds, usually with a thickness of only a few nanometers. This method of preparing SAMs by spontaneous adsorption on solid surfaces through chemical bond interactions is simple, efficient, and extremely stable.

[0060] The regrowth method of the epitaxial layer of the semiconductor structure provided in this embodiment, on the one hand, uses a self-assembled monolayer as a passivation film on the surface of the semiconductor structure after etching, which can ensure that the semiconductor structure does not contact the air during the process from etching to epitaxial regrowth, effectively inhibits the occurrence of oxidation, ensures that the surface of the semiconductor structure will not produce an oxide layer before the epitaxial layer is formed, and realizes effective protection of the semiconductor structure; on the other hand, the thickness of the self-assembled monolayer is nanometer-level, and it is easy to decompose at high temperature, so the self-assembled monolayer can be removed by heating before the epitaxial layer is formed, and no damage will be caused to the surface of the semiconductor structure, and the product after the decomposition of the self-assembled monolayer will not cause any pollution to the wafer and the equipment. Therefore, the regrowth method of the epitaxial layer of the semiconductor structure provided by the present invention uses a self-assembled monolayer as a passivation film on the surface of the semiconductor structure after etching, which can ensure that the surface of the semiconductor structure will not produce an oxide layer before the epitaxial layer is formed, can improve the interface quality between the epitaxial layer and the semiconductor structure, improve the quality and efficiency of the epitaxial layer growth, and then improve the electrical and optical properties of the device finally formed, and prevent the performance degradation and aging of the device caused by oxidation.

[0061] Further, in some embodiments, the second temperature is greater than the first temperature.

[0062] The present embodiment provides a method for regrowth of an epitaxial layer of a semiconductor structure. The second temperature for regrowth to form an epitaxial layer is greater than the first temperature for removing the self-assembled monolayer. The self-assembled monolayer can be first heated to the first temperature in the growth device to remove the self-assembled monolayer, and then heated to the second temperature to regrow the epitaxial layer on the surface of the semiconductor structure. No additional equipment and process are required to remove the self-assembled monolayer. It is also ensured that no oxide layer is generated on the surface of the semiconductor structure before the epitaxial layer is formed, which can improve the protective effect of the passivation layer on the surface of the semiconductor structure and simplify the process flow. In addition, the second temperature is greater than the first temperature, and the residue of the self-assembled monolayer can be further removed during the heating process of the epitaxial growth to ensure complete removal.

[0063] Furthermore, in some embodiments, the thickness of the self-assembled monolayer is 2 nm to 3 nm, for example, 2 nm, 2.3 nm, 2.5 nm, 2.8 nm or 3 nm.

[0064] The method for regrowth of an epitaxial layer of a semiconductor structure provided in this embodiment is aimed at the semiconductor front-end process. It provides a temporary passivation protective layer for the wafer surface during the wafer manufacturing process to ensure that the wafer is not oxidized during the period from the completion of wet etching to the sending of the wafer to the epitaxial growth equipment. Therefore, it is sufficient to provide protection for a minimum of a few minutes, so a self-assembled monolayer film with a thickness of 2nm~3nm is selected.

[0065] The thickness of the self-assembled monolayer film is 2nm~3nm. Although it cannot provide long-term protection as a permanent protective layer, it can ensure that the semiconductor structure will not be oxidized after at least one day. At the same time, the decomposition products of the self-assembled monolayer film are easy to remove and will not cause any pollution to the semiconductor structure and equipment.

[0066] Further, in some embodiments, the first temperature is 150ºC to 300ºC, such as 150ºC, 180ºC, 220ºC, 270ºC or 300ºC;

[0067] The second temperature is 550°C to 800°C, such as 550°C, 600°C, 650°C, 700°C or 800°C;

[0068] The step of heating to a first temperature to remove the self-assembled monolayer film includes a heating stage and a constant temperature stage, and the duration of the constant temperature stage is a first duration; the first duration is 10 minutes to 20 minutes, for example, 10 minutes, 12 minutes, 15 minutes, and 20 minutes.

[0069] The first temperature is the decomposition temperature of the self-assembled monolayer. When the temperature of the self-assembled monolayer is greater than the first temperature, the self-assembled monolayer will decompose. The second temperature is the growth temperature of the epitaxial layer. When the temperature of the growth device is greater than the second temperature, an epitaxial layer can be grown on the semiconductor structure.

[0070] In a specific implementation, in order to ensure that the self-assembled monolayer film on the surface of the semiconductor structure is completely removed, after heating to the first temperature, the self-assembled monolayer film is removed for a first period of time.

[0071] In one example, the first temperature is 300°C, the first time is 10 minutes, a GaAs wafer having a self-assembled monolayer film formed thereon is placed in a growth device, heated to 300°C and maintained for 10 minutes, and the self-assembled monolayer film is removed.

[0072] Furthermore, in some embodiments, before the step of placing the etched semiconductor structure into the self-assembling organic solution, the step further includes:

[0073] Cleaning the etched semiconductor structure to remove oxide on the surface of the semiconductor structure;

[0074] The cleaned semiconductor structure is placed in a first ammonia solution (NH 4 OH solution) temporarily stored;

[0075] The 30% ammonia solution and H 2 The volume ratio of O is: 30% ammonia solution: H 2O = 1:9~1:25;

[0076] The temporary storage time is less than 10 minutes.

[0077] In a specific implementation, the semiconductor structure after etching is first cleaned to remove the oxide on the surface of the semiconductor structure; then, the cleaned semiconductor structure is directly placed in a first ammonia solution for temporary storage without drying the semiconductor structure, to ensure that the surface of the wafer, especially the surface exposed by the semiconductor structure after etching, is not directly exposed to the air. The volume ratio of the first ammonia solution is: 30% ammonia solution: H 2 O=1:9~1:25; NH 4 OH solution can effectively inhibit oxidation and hardly cause any etching or impact on the wafer. In addition, the temporary storage time is less than 10 minutes, which will not affect the production capacity and provide sufficient time to prepare the self-assembled organic solution.

[0078] In one example, the semiconductor structure is a GaAs wafer, and the first ammonia solution is prepared by diluting 30% (mass concentration) ammonia solution with water. The first ammonia solution ratio is: 30% ammonia solution: H 2 O=1:20 (volume ratio), of which 30% ammonia solution is NH 4 OH solution.

[0079] The present embodiment provides a method for regrowth of an epitaxial layer of a semiconductor structure. After removing the oxide on the surface of the etched semiconductor structure and before forming a self-assembled monolayer film, the cleaned semiconductor structure is temporarily stored in a first ammonia solution, wherein the 30% ammonia solution and H 2 Volume ratio of O: 30% ammonia solution: H 2 O=1:9~1:25, the temporary storage time is less than 10 minutes, which can ensure that the semiconductor structure is not exposed to air during the process from etching to the formation of the self-assembled monolayer film, effectively inhibiting the occurrence of oxidation, while having no effect on the semiconductor structure and will not affect the production capacity.

[0080] Furthermore, in some embodiments, the step of placing the etched semiconductor structure into the self-assembling organic solution includes:

[0081] In a nitrogen atmosphere, the semiconductor structure is taken out from the first ammonia aqueous solution and placed in the self-assembly organic solution within less than 10 seconds.

[0082] In the specific implementation, the etched semiconductor structure is taken out from the first ammonia solution and placed in the prepared alkylthiol solution within 10 seconds. 4The residual OH solution is added dropwise to the alkylthiol solution. 4 The OH ratio is controlled within 10%, which will not affect the film formation. 2 The reaction was carried out in a glove box to prevent the intrusion of oxygen.

[0083] The present embodiment provides a method for regrowth of an epitaxial layer of a semiconductor structure. In a nitrogen atmosphere, the semiconductor structure is taken out from a first ammonia solution and placed in a self-assembled organic solution within less than 10 seconds. The self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure. This ensures that the semiconductor structure is not exposed to air during the process from etching to the formation of the self-assembled monolayer film, and can effectively inhibit oxidation without causing any impact on the semiconductor structure.

[0084] Furthermore, in some embodiments, after the step of forming a self-assembled monolayer film on the surface of the semiconductor structure, the method further includes:

[0085] The semiconductor structure is removed from the nitrogen atmosphere and dried.

[0086] In specific implementation, after the self-assembled monolayer film is grown, the semiconductor structure is removed from the nitrogen atmosphere and dried. The drying method may be to put it into a spin dryer for drying or blow it with nitrogen. Other drying methods may be selected as needed, which are not limited in this embodiment.

[0087] Furthermore, in some embodiments, the step of placing the semiconductor structure formed with the self-assembled monolayer film into a growth device and heating it to a first temperature to remove the self-assembled monolayer film further includes:

[0088] Hydrogen is passed through the surface of the semiconductor structure to remove byproducts produced during the self-assembled monolayer film process.

[0089] In a specific implementation, since the thickness of the self-assembled monolayer film is at the nanometer level and it is easy to decompose at high temperature, the self-assembled monolayer film is first heated to be removed before forming the epitaxial layer, and hydrogen is passed through the surface of the semiconductor structure. The hydrogen can be used to remove the by-products in the process of the self-assembled monolayer film, so that the self-assembled monolayer film is completely removed without remaining on the semiconductor surface or causing any damage to the surface of the semiconductor structure. In addition, the products after the decomposition of the self-assembled monolayer film will not cause any pollution to the wafer and the equipment, which can improve the interface quality between the epitaxial layer and the semiconductor structure, and improve the quality and efficiency of the epitaxial layer growth.

[0090] Further, in some embodiments, the material of the semiconductor structure is a III-V compound material;

[0091] The material of the self-assembled monolayer film is an organic compound containing thiol groups.

[0092] In some other embodiments, the material of the semiconductor structure may also be a derivative material of group III-V compounds; and the material of the self-assembled monolayer film may be an organic compound containing a thiol group.

[0093] In other embodiments, the material of the semiconductor structure may be other semiconductor materials, and appropriate materials are selected to form a self-assembled monolayer film.

[0094] Further, in some embodiments, the III-V compound material includes GaAs, InP, InAs, InGaAs or GaN;

[0095] The material of the self-assembled monolayer film is alkylthiol or 3-mercaptopropyltrimethoxysilane.

[0096] In some embodiments, for GaAs wafers and InP wafers, alkylthiols with n of 16 and 18 are selected, corresponding to hexadecyl mercaptan (C 16 SH) and octadecyl mercaptan (C 18 SH), which are two alkylthiols currently widely used in the industry. When the n value is high, the monolayer film has higher quality and better coverage on the wafer, but it takes longer time and higher temperature to remove in the subsequent steps. When the n value is low, the monolayer film has poor coverage on the wafer, which needs to be compensated by increasing the film formation time and film formation temperature. Accordingly, it is easier to remove in the subsequent steps.

[0097] Further, in some embodiments, the material of the semiconductor structure is GaAs; the material of the self-assembled monolayer is alkylthiol;

[0098] The step of preparing the self-assembling organic solution comprises:

[0099] Mixing anhydrous ethanol and alkyl mercaptan evenly to obtain a first solution;

[0100] Adding a second ammonia solution with a concentration of 30% to the first solution to obtain an alkylthiol solution, wherein the volume ratio of the second ammonia solution to the first solution is 2% to 10%, for example, 2%, 4%, 7% or 10%;

[0101] A degassing treatment is performed to remove oxygen in the alkyl mercaptan solution.

[0102] In specific implementation, when preparing the first solution, different alkyl mercaptans have different solubility in anhydrous ethanol. For example, 100 mL of anhydrous ethanol can only dissolve 500 mg of octadecyl mercaptan at most. When preparing the alkyl mercaptan solution, the volume ratio of the second ammonia solution to the first solution is the second ammonia solution: the first solution = 2% to 10%. The volume ratio of the second ammonia solution to the first solution is controlled at 2% to 10%, which is conducive to forming a self-assembled monolayer film with full coverage and good quality.

[0103] In one example, 100-400 mg of octadecyl mercaptan is added to every 100 mL of anhydrous ethanol to obtain a first solution; a second ammonia solution having a concentration of 30% is added to the first solution at a volume ratio of 2%-10%, and the mixture is mixed evenly to obtain a final alkyl mercaptan solution.

[0104] In this embodiment, the obtained alkyl mercaptan solution is subjected to degassing treatment in order to remove oxygen dissolved in the alkyl mercaptan solution. In specific implementation, the solution can be placed in a sealed container for vacuuming by reducing pressure, or ultrasonic degassing can be performed using an ultrasonic cleaner.

[0105] In one example, a container containing the alkylthiol solution is placed in an ultrasonic cleaning machine and operated for 20 minutes without load to complete the degassing process.

[0106] Furthermore, in some embodiments, after the step of performing a degassing treatment to remove oxygen from the alkylthiol solution, the method further includes: heating the degassed alkylthiol solution to a third temperature and maintaining the temperature at a constant temperature to prepare for the subsequent growth of a self-assembled monolayer.

[0107] The third temperature is 30°C to 50°C. The degassed alkylthiol solution is kept at a constant temperature of 30°C to 50°C, so that in the subsequent process of forming a self-assembled monolayer film on the surface of the semiconductor structure, the temperature of the alkylthiol solution is maintained at 30°C to 50°C, which can prepare for the subsequent growth of the self-assembled monolayer film, so that when the wafer is directly placed in the alkylthiol solution, the self-assembled monolayer film starts to grow immediately without the need for reheating, shortening the growth time of the self-assembled monolayer film, and ensuring that a self-assembled monolayer film with full coverage and good quality can be generated in the shortest time.

[0108] Furthermore, in some embodiments, during the process of forming a self-assembled monolayer film on the surface of the semiconductor structure, the temperature of the self-assembled organic solution is 30° C. to 50° C., and the formation time of the self-assembled monolayer film is 30 mins to 50 mins.

[0109] In a specific implementation, during the process of forming a self-assembled monolayer on the surface of the semiconductor structure, the temperature of the self-assembled organic solution is 30°C to 50°C, and the formation time of the self-assembled monolayer is 30 minutes to 50 minutes, which can ensure that a layer of self-assembled monolayer that completely covers the entire wafer can be generated on the surface of the semiconductor structure in the shortest time. If the growth time is too short, it is not enough to form a completely covered self-assembled monolayer, and the passivation effect is not good; if the growth time is too long, the polymer chains of the formed self-assembled monolayer will have lateral connections, increasing the difficulty of the subsequent in-situ removal process.

[0110] Example 2

[0111] refer to Figure 2 This embodiment provides a specific process of a method for regrowth of an epitaxial layer of a semiconductor structure, including steps S201-S211.

[0112] S201, providing an etched GaAs wafer.

[0113] S202, adding 100 mg to 400 mg of octadecyl mercaptan to every 100 mL of anhydrous ethanol to obtain a first solution.

[0114] S203, adding a second ammonia solution with a concentration of 30% into the first solution at a volume ratio of 2% to 10%, and mixing them evenly to obtain a final alkylthiol solution.

[0115] S204, placing the container containing the alkyl mercaptan solution into an ultrasonic cleaning machine and running it for 20 minutes without load to complete degassing treatment and remove oxygen in the alkyl mercaptan solution.

[0116] S205, heating the degassed alkyl mercaptan solution to 30°C~50°C and maintaining the temperature therein.

[0117] S206, cleaning the etched GaAs wafer to remove oxides on the surface of the GaAs wafer.

[0118] S207, temporarily storing the cleaned GaAs wafer in a first ammonia solution; wherein the volume ratio of the first ammonia solution is: 30% ammonia solution: H 2 O=1:20; temporary storage time is less than 10 minutes.

[0119] S208, in a nitrogen atmosphere, taking the GaAs wafer out of the first ammonia solution, and placing it in a self-assembled organic solution within less than 10 seconds, wherein the self-assembled organic solution forms a self-assembled monolayer film on the surface of the GaAs wafer, and the self-assembled monolayer film serves as a passivation film; wherein the temperature of the alkylthiol solution is 30°C~50°C, and the formation time of the self-assembled monolayer film is 30mins~50mins.

[0120] S209, the GaAs wafer with the self-assembled monolayer film formed thereon is removed from the nitrogen atmosphere and subjected to a drying process.

[0121] S210, placing the GaAs wafer with the self-assembled monolayer film formed thereon into a growth device, heating it to 300° C. and maintaining it for 10 minutes to remove the self-assembled monolayer film; at the same time, passing hydrogen gas on the surface of the GaAs wafer to remove byproducts in the process of the self-assembled monolayer film.

[0122] S211, heating to 600°C to regrow the GaAs wafer surface to form an epitaxial layer.

[0123] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for regrowth of an epitaxial layer of a semiconductor structure, characterized in that: include: Providing an etched semiconductor structure; The material of the semiconductor structure is a III-V compound material; Cleaning the semiconductor structure to remove oxide on the surface of the semiconductor structure; The cleaned semiconductor structure is temporarily stored in a first ammonia solution; the volume ratio of the 30% ammonia solution to H2O in the first ammonia solution is: 30% ammonia solution: H2O=1:9-1:25; the temporary storage time is less than 10 minutes; preparing a self-assembling organic solution; The step of preparing the self-assembly organic solution comprises: mixing anhydrous ethanol and alkylthiol evenly to obtain a first solution; adding a second ammonia aqueous solution with a concentration of 30% to the first solution to obtain an alkylthiol solution, wherein the volume ratio of the second ammonia aqueous solution to the first solution is 2% to 10%; performing a degassing treatment to remove oxygen in the alkylthiol solution; The etched semiconductor structure is placed in the self-assembled organic solution, and the self-assembled organic solution forms a self-assembled monolayer film on the surface of the semiconductor structure, and the self-assembled monolayer film serves as a passivation film; the material of the self-assembled monolayer film is alkylthiol; the temperature of the self-assembled organic solution is 30° C. to 50° C., and the formation time of the self-assembled monolayer film is 30 minutes to 50 minutes; The semiconductor structure formed with the self-assembled monolayer film is placed in a growth device, and heated to a first temperature to remove the self-assembled monolayer film; the first temperature is the decomposition temperature of the self-assembled monolayer film; hydrogen is passed through the surface of the semiconductor structure to remove byproducts of the heating and decomposition process of the self-assembled monolayer film; Heating to a second temperature to re-grow an epitaxial layer on the surface of the semiconductor structure; the second temperature is the growth temperature of the epitaxial layer; the second temperature is greater than the first temperature; the epitaxial layer is GaAs, InP, GaN or AlAs.

2. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 1, characterized in that: The thickness of the self-assembled monolayer film is 2nm-3nm.

3. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 2, characterized in that: The first temperature is 150°C to 300°C; The second temperature is 550°C to 800°C; The step of heating to a first temperature to remove the self-assembled monolayer film comprises a temperature rising stage and a constant temperature stage, and the duration of the constant temperature stage is a first duration; The first duration is 10 minutes to 20 minutes.

4. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 1, characterized in that: The step of placing the etched semiconductor structure into the self-assembling organic solution comprises: In a nitrogen atmosphere, the semiconductor structure is taken out from the first ammonia aqueous solution and placed in the self-assembly organic solution within less than 10 seconds.

5. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 4, characterized in that: After the step of forming a self-assembled monolayer film on the surface of the semiconductor structure, the method further comprises: The semiconductor structure is removed from the nitrogen atmosphere and dried.

6. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 1, characterized in that: The III-V group compound material includes GaAs, InP, InAs, InGaAs or GaN.

7. The method for regrowth of an epitaxial layer of a semiconductor structure according to claim 6, characterized in that: The material of the semiconductor structure is GaAs.

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