Methods for forming semiconductor structures

Abstract

A method for forming a semiconductor structure includes: providing a substrate; forming a trench within the substrate; performing a first oxidation treatment on the sidewalls and bottom of the trench using ISSG to form a first oxide layer; performing a second oxidation treatment on the sidewalls and bottom of the trench using RTO to form a second oxide layer between the first oxide layer and the substrate; and filling the trench with a dielectric material after forming the second oxide layer to form an isolation structure. By sequentially using ISSG and RTO to form the first and second oxide layers, the quality of the oxide layer on the sidewalls of the isolation structure can be further improved, effectively reducing leakage current and lowering the defect density at the interface between the isolation structure and the substrate.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to a method for forming a semiconductor structure. Background Technology

[0002] With the rapid development of semiconductor technology, the feature size of semiconductor devices has been significantly reduced, which has placed higher demands on chip manufacturing processes. One of the challenging issues is to uniformly and non-porously fill the insulating dielectric between thin film layers or in trenches to provide sufficient and effective isolation and protection.

[0003] With the advancement of technology nodes and the entry of semiconductor processes into the deep submicron era, in order to meet the requirements of high-density integrated circuits and solve the bird's beak effect and white band effect in LOCOS isolation technology, the isolation between devices below 0.13μm has mostly adopted the STI (Shallow Trench Isolation) isolation structure.

[0004] However, the quality of the STI isolation structure formed by existing technology needs to be further improved. Summary of the Invention

[0005] The problem addressed by this invention is how to further improve the quality of the linear oxide layer in the STI isolation structure.

[0006] To address the above problems, the present invention provides a method for forming a semiconductor structure, comprising:

[0007] A substrate is provided; a trench is formed in the substrate; the sidewalls and bottom of the trench are subjected to a first oxidation treatment by means of ISSG to form a first oxide layer; the sidewalls and bottom of the trench are subjected to a second oxidation treatment by means of RTO to form a second oxide layer between the first oxide layer and the substrate; after the second oxide layer is formed, a medium is filled in the trench to form an isolation structure.

[0008] Optionally, in the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the second oxide layer formed is combined with the first oxide layer to form a linear stack.

[0009] Optionally, in the step of performing the first oxidation treatment on the sidewalls and bottom of the trench using ISSG, the thickness of the first oxide layer is [missing information]. to Within the range; in the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the thickness of the second oxide layer formed is within to Within the range.

[0010] Optionally, in the step of performing the first oxidation treatment on the sidewalls and bottom of the trench by means of ISSG, the process temperature is in the range of 950°C to 1150°C, and the process gases include hydrogen and oxygen.

[0011] Optionally, in the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the process temperature is in the range of 850°C to 1150°C, and the process gases include oxygen and nitrogen.

[0012] Optionally, it also includes: after filling the trench with a medium to form an isolation structure, performing a high-temperature annealing process.

[0013] Optionally, in the high-temperature annealing step, the process temperature is in the range of 1000℃ to 1150℃ and the process time is in the range of 15s to 20s.

[0014] Optionally, in the step of high-temperature annealing, the high-temperature annealing is performed in a hydrogen-containing atmosphere.

[0015] Optionally, in the step of performing high-temperature annealing, the hydrogen-containing atmosphere includes hydrogen gas.

[0016] Optionally, in the step of high-temperature annealing, the hydrogen-containing atmosphere further includes an inert gas.

[0017] Optionally, in the step of high-temperature annealing, the inert gas includes at least one of nitrogen and argon.

[0018] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0019] In this invention, after forming trenches in the substrate and before filling the trenches with a dielectric layer to form an isolation structure, the sidewalls and bottom of the trenches are first oxidized using ISSG; then, the sidewalls and bottom of the trenches are oxidized using RTO. ISSG oxidation produces oxides with better overall uniformity and faster growth rate; RTO oxidation produces oxides with higher density and surface smoothness, fewer defects, and better passivation. Therefore, using ISSG and RTO sequentially to form the first and second oxide layers can further improve the quality of the oxides on the sidewalls of the isolation structure, effectively reducing leakage current and lowering the defect density at the interface between the isolation structure and the substrate.

[0020] In an optional embodiment of the present invention, after filling the trench with a medium to form an isolation structure, a high-temperature annealing treatment is performed. The thermal effect of the high-temperature annealing treatment after forming the isolation structure promotes structural relaxation of the formed oxide. This structural relaxation of the oxide material not only increases density but also releases stress, effectively improving the quality of the formed isolation structure.

[0021] In an optional embodiment of the present invention, the high-temperature annealing treatment after the formation of the isolation structure is carried out in a hydrogen-containing atmosphere. High-temperature annealing in a hydrogen-containing atmosphere allows hydrogen to diffuse effectively within the material, thereby reacting with defects in the oxide to repair those defects and passivating the substrate surface to reduce interface states. Attached Figure Description

[0022] Figures 1 to 3 This is a schematic diagram of the various steps in a method for forming a semiconductor structure.

[0023] Figures 4 to 7 This is a schematic diagram of the various steps in an embodiment of the semiconductor structure formation method of the present invention. Detailed Implementation

[0024] As can be seen from the background technology, the quality of isolation structures formed by existing technologies needs improvement. This paper analyzes the reasons why the quality of isolation structures needs to be improved using a semiconductor structure formation method:

[0025] refer to Figures 1 to 3 The diagram shows a schematic representation of the steps involved in forming a semiconductor structure.

[0026] The forming method includes: such as Figure 1 As shown, the substrate 11 is cleaned to obtain a clean surface; after cleaning, an oxide layer 12 and a nitride layer 13 are sequentially formed on the surface of the substrate 11; by photolithography, a mask pattern is formed on the nitride layer 13 and etched to form a groove 14 in the substrate 11.

[0027] After the groove 14 is formed, as Figure 2 As shown, a linear oxide layer 15 is formed on the sidewalls and bottom of the trench 14; subsequently, as... Figure 3 As shown, oxide is filled into the trench in which the linear oxide layer 15 is formed and excess oxide is removed to form an isolation structure 16; after the isolation structure 16 is formed, the damage is repaired by rapid thermal oxidation and the nitride layer is etched away.

[0028] At the sharp corners of the isolation structure 16, the electric field tends to concentrate, which can lead to a decrease in device performance. Therefore, after the trench 14 is formed but before the isolation structure 16 is formed, oxides are formed on the sidewalls and bottom of the trench 14 to avoid leakage problems caused by parasitic transistors, electric field concentration, etc., and can also repair the damage caused by etching.

[0029] like Figure 2 As shown, in the above method, the sidewalls and bottom of the trench 14 are oxidized by ISSG (In-Situ Steam Generation) to form oxides. During the ISSG reaction, a large number of gaseous active free radicals are generated, among which oxygen atoms are highly reactive and can easily cause the surface oxygen atoms to react before forming a regular arrangement. In addition, Si-H bonds and Si-OH bonds are easily generated during the oxidation process, resulting in surface defects.

[0030] To solve the aforementioned technical problem, the present invention provides a method for forming a semiconductor structure, comprising:

[0031] A substrate is provided; a trench is formed in the substrate; the sidewalls and bottom of the trench are subjected to a first oxidation treatment by means of ISSG to form a first oxide layer, wherein the process gas used for the first oxidation treatment contains hydrogen; the sidewalls and bottom of the trench are subjected to a second oxidation treatment by means of RTO to form a second oxide layer between the first oxide layer and the substrate, wherein the process gas used for the second oxidation treatment does not contain hydrogen; after the second oxide layer is formed, a medium is filled in the trench to form an isolation structure.

[0032] In this invention, after forming trenches in the substrate and before filling the trenches with a dielectric layer to form an isolation structure, the sidewalls and bottom of the trenches are first oxidized using ISSG; then, the sidewalls and bottom of the trenches are oxidized using RTO. ISSG oxidation produces oxides with better overall uniformity and faster growth rate; RTO oxidation produces oxides with higher density and surface smoothness, fewer defects, and better passivation. Therefore, sequentially using ISSG and RTO to form the first and second oxide layers can further improve the quality of the oxides on the sidewalls of the isolation structure, effectively reducing leakage current and lowering the defect density at the interface between the isolation structure and the substrate.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] refer to Figures 4 to 7 The diagram shows a schematic representation of the various steps in an embodiment of the semiconductor structure of the present invention.

[0035] The forming method includes:

[0036] Substrate 110 is provided;

[0037] A trench 120 is formed within the substrate 110;

[0038] The sidewalls and bottom of the trench 120 are subjected to a first oxidation treatment by means of ISSG to form a first oxide layer 131, wherein the process gas used in the first oxidation treatment contains hydrogen.

[0039] The sidewalls and bottom of the trench 120 are subjected to a second oxidation treatment by means of RTO, and a second oxide layer 132 is formed between the first oxide layer 131 and the substrate 110. The process gas used in the second oxidation treatment does not contain hydrogen.

[0040] After the second oxide layer 132 is formed, a medium is filled in the trench 120 to form an isolation structure 140.

[0041] The technical solution of the semiconductor structure formation method embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0042] First, refer to Figure 4 Substrate 110 is provided.

[0043] The substrate 110 is used to improve the process operation platform and mechanical support.

[0044] In some embodiments of the present invention, the substrate 110 is a silicon substrate, and the material of the substrate 110 is silicon. Specifically, the material of the substrate 110 may be selected from monocrystalline silicon, polycrystalline silicon, or amorphous silicon. In other embodiments, the material of the substrate may also be selected from silicon, germanium, gallium arsenide, or silicon-germanium compounds; the substrate may also be selected from materials having an epitaxial layer or a silicon-on-epitaxy layer structure; the substrate may also be other semiconductor materials.

[0045] It should be noted that in some embodiments, after the substrate 110 is provided, the surface of the substrate 110 is cleaned to obtain a clean substrate surface.

[0046] like Figure 4 As shown, in some embodiments, the formation method further includes: after providing a substrate 110, forming an oxide layer 111 and a nitride layer 112 on the substrate 110.

[0047] The oxide layer 111 serves as a buffer layer between the nitride layer 112 and the substrate 110 to relieve the stress of the nitride layer 112 on the substrate 110; the nitride layer 112 serves as a stop layer in subsequent processes.

[0048] In some embodiments, the oxide layer 111 can be formed on the surface of the substrate 110 by oxidizing the surface of the substrate 110; the oxide layer 111 can also be formed on the surface of the substrate 110 by deposition.

[0049] In some embodiments, the nitrided layer 112 can be formed on the surface of the oxide layer 111 by nitriding the surface of the oxide layer; the nitrided layer 112 can also be formed on the surface of the oxide layer 111 by deposition.

[0050] Continue to refer to Figure 4 A trench 120 is formed in the substrate 110.

[0051] The groove 120 is used to provide a structural basis for the formation of the isolation structure.

[0052] Specifically, such as Figure 4 As shown, the step of forming the trench 120 in the substrate 110 includes: forming a mask layer on the substrate 110, patterning the mask layer by photolithography to form a patterned mask layer; using the patterned mask layer as a mask, etching the substrate 110 to form the trench 120 in the substrate 110.

[0053] The mask layer is used for pattern transfer. For example, the mask layer may include a photoresist layer, and the mask layer is patterned by a photolithography process including exposure and development to form a patterned mask layer; wherein the pattern in the mask layer may define the position and size of the trench 120.

[0054] For example, in the step of etching the substrate 110 to form the trench 120 in the substrate 110, the substrate 110 can be etched by at least one of dry etching and wet etching.

[0055] Next, refer to Figure 5 The sidewalls and bottom of the trench 120 are subjected to a first oxidation treatment by means of ISSG to form a first oxide layer 131.

[0056] The first oxide layer 131 is used to smooth sharp corners and repair damage; the first oxidation treatment of the sidewalls and bottom of the trench 120 is carried out by ISSG (In-Situ Steam Generation), which has the advantages of fast generation speed and good uniformity.

[0057] Specifically, in some embodiments, the substrate 110 is a silicon substrate; in the step of performing the first oxidation treatment on the sidewalls and bottom of the trench 120 by means of ISSG, the material of the first oxide layer 131 formed is silicon oxide.

[0058] In some embodiments of the present invention, in the step of performing the first oxidation treatment on the sidewalls and bottom of the trench 120 by means of ISSG, the thickness of the first oxide layer 131 formed is... to Within the specified range, the thickness of the first oxide layer 131 formed is appropriate, which can effectively smooth sharp corners and repair etching damage while ensuring process efficiency.

[0059] In some embodiments, during the first oxidation treatment of the sidewalls and bottom of the trench 120 via ISSG, the process temperature is in the range of 950°C to 1150°C, and the process gases include hydrogen and oxygen. The suitable temperature of the first oxidation treatment effectively activates the process gases, ensuring the ISSG reaction efficiency while forming a highly uniform first oxide layer 131.

[0060] Afterwards, refer to Figure 6 The sidewalls and bottom of the trench 120 are subjected to a second oxidation treatment by means of RTO, and a second oxide layer 132 is formed between the first oxide layer 131 and the substrate 110.

[0061] The second oxidation treatment is used to further repair defects at the interface between the first oxide layer 131 and the substrate 110, thereby repairing interface defects and improving the quality of the isolation structure.

[0062] Specifically, in some embodiments, the substrate 110 is a silicon substrate; in the step of performing a second oxidation treatment on the sidewalls and bottom of the trench 120 by means of RTO, the material of the second oxide layer 132 formed is silicon oxide.

[0063] In some embodiments of the present invention, in the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the formed second oxide layer 132 and the first oxide layer 131 cooperate to form a linear stack 130. In the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the thickness of the formed second oxide layer 132 is determined by the technical requirements of the linear stack 130 and the thickness of the formed first oxide layer 131.

[0064] In some embodiments, during the second oxidation treatment of the sidewalls and bottom of the trench 120 by RTO, the thickness of the second oxide layer 132 formed is... to Within the specified range, the thickness of the second oxide layer 132 is appropriate, and the thickness ratio between the second oxide layer 132 and the first oxide layer 131 is suitable, enabling the rapid and effective formation of the linear stack 130, ensuring process efficiency. Moreover, the formed linear stack 130 has better quality, fewer defects, and higher overall quality.

[0065] In some embodiments, during the second oxidation treatment of the sidewalls and bottom of the trench 120 using RTO, the process temperature is in the range of 850°C to 1150°C, and the process gases include oxygen and nitrogen. During the second oxidation treatment of the sidewalls and bottom of the trench 120 using RTO, hydrogen is not present, and Si-H bonds and Si-OH bonds are not formed. The resulting oxide structure has higher density and smoothness, fewer defects, and better passivation effect.

[0066] refer to Figure 7 After the second oxide layer 132 is formed, a medium is filled in the trench 120 to form an isolation structure 140.

[0067] Specifically, such as Figure 7 As shown, the step of filling the trench 120 with a medium to form an isolation structure 140 includes: filling the trench 120 with a medium material, the formed medium material filling the trench 120 and extending to the nitride layer and the oxide layer 111; removing excess medium material, retaining the medium material in the trench 140, and forming the isolation structure 140.

[0068] In some embodiments, the step of filling the trench 120 with dielectric material can be performed by HDPCVD (High Density Plasma Chemical Vapor Deposition); in the step of removing excess dielectric material from the nitride layer and the oxide layer 111, the excess dielectric material on the nitride layer and the oxide layer 111 can be removed by CMP (Chemical Mechanical Polishing) with the nitride layer as the stop layer, thereby forming the isolation structure 140.

[0069] It should be noted that, in some embodiments, after removing excess dielectric material and forming the isolation structure 140, the forming method further includes: removing the nitride layer 112 (e.g., Figure 6 (As shown). For example, the nitride layer 112 can be removed by wet etching.

[0070] In some embodiments of the present invention, the forming method further includes: after filling the trench 120 with a medium to form an isolation structure 140, performing a high-temperature annealing treatment. The thermal effect of the high-temperature annealing treatment can promote structural relaxation of the formed oxide, thereby achieving the effects of increasing density and releasing stress.

[0071] In some embodiments, the high-temperature annealing step involves a process temperature ranging from 1000°C to 1150°C and a process time ranging from 15 seconds to 20 seconds. The appropriate temperature and time for high-temperature annealing effectively balance thermal budget and annealing effect, allowing for improved insulation structure quality while controlling process analysis.

[0072] In some embodiments, the high-temperature annealing step is performed in a hydrogen-containing atmosphere. In a hydrogen-containing atmosphere, the hydrogen can diffuse effectively within the material, reacting with defects in the oxide to repair them and passivating the substrate surface to reduce interface states. For example, in the high-temperature annealing step, the hydrogen-containing atmosphere includes hydrogen gas.

[0073] In some embodiments, during the high-temperature annealing step, the hydrogen-containing atmosphere further includes an inert gas. The atmosphere used for the high-temperature annealing process also includes an inert gas for protective purposes. For example, during the high-temperature annealing step, the inert gas includes at least one of nitrogen and argon.

[0074] In summary, after forming trenches in the substrate and before filling the trenches with a dielectric layer to form an isolation structure, the sidewalls and bottom of the trenches are first oxidized using ISSG; then, the sidewalls and bottom of the trenches are oxidized using RTO. ISSG oxidation produces oxides with better overall uniformity and faster growth rate; RTO oxidation produces oxides with higher density and surface smoothness, fewer defects, and better passivation. Therefore, using ISSG and RTO sequentially to form the first and second oxide layers can further improve the quality of the oxides on the sidewalls of the isolation structure, effectively reducing leakage current and lowering the defect density at the interface between the isolation structure and the substrate.

[0075] Furthermore, after filling the trench with a medium to form an isolation structure, a high-temperature annealing process is performed. The thermal effect of this process promotes structural relaxation in the formed oxide material. This relaxation not only increases density but also releases stress, effectively improving the quality of the formed isolation structure.

[0076] Furthermore, the high-temperature annealing process following the formation of the isolation structure is carried out in a hydrogen-containing atmosphere. In this atmosphere, the hydrogen effectively diffuses within the material, reacting with defects in the oxide to repair them and passivating the substrate surface to reduce interface states.

[0077] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for forming a semiconductor structure, characterized in that, include: Provide substrate; Trenches are formed within the substrate; The sidewalls and bottom of the trench are subjected to a first oxidation treatment using the ISSG method to form a first oxide layer; The sidewalls and bottom of the trench are subjected to a second oxidation treatment by RTO, forming a second oxide layer between the first oxide layer and the substrate; After the second oxide layer is formed, a medium is filled into the trench to form an isolation structure.

2. The forming method as described in claim 1, characterized in that, In the step of performing a second oxidation treatment on the sidewalls and bottom of the trench using RTO, the formed second oxide layer and the first oxide layer cooperate to form a linear stack.

3. The forming method as described in claim 2, characterized in that, In the step of performing the first oxidation treatment on the sidewalls and bottom of the trench using the ISSG method, the thickness of the first oxide layer formed is... to Within the range; In the step of performing a second oxidation treatment on the sidewalls and bottom of the trench using RTO, the thickness of the second oxide layer formed is... to Within the range.

4. The forming method as described in claim 1, characterized in that, In the step of performing the first oxidation treatment on the sidewalls and bottom of the trench using ISSG, the process temperature is in the range of 950°C to 1150°C, and the process gases include hydrogen and oxygen.

5. The forming method as described in claim 1, characterized in that, In the step of performing a second oxidation treatment on the sidewalls and bottom of the trench by means of RTO, the process temperature is in the range of 850°C to 1150°C, and the process gases include oxygen and nitrogen.

6. The forming method as described in claim 1, characterized in that, Also includes: After the groove is filled with a medium to form an isolation structure, a high-temperature annealing process is performed.

7. The forming method as described in claim 6, characterized in that, In the high-temperature annealing process, the process temperature is in the range of 1000℃ to 1150℃ and the process time is in the range of 15s to 20s.

8. The forming method as described in claim 6, characterized in that, In the high-temperature annealing process, the high-temperature annealing is performed in a hydrogen-containing atmosphere.

9. The forming method as described in claim 8, characterized in that, In the step of high-temperature annealing, the hydrogen-containing atmosphere includes hydrogen gas.

10. The forming method as described in claim 8, characterized in that, In the high-temperature annealing process, the hydrogen-containing atmosphere further includes an inert gas.

11. The forming method as described in claim 10, characterized in that, In the high-temperature annealing process, the inert gas includes at least one of nitrogen and argon.

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