Method for forming a patterned structure on a wafer

Abstract

This invention relates to the field of photolithography in semiconductor manufacturing, and discloses a method for forming patterned structures on a wafer. A method for forming patterned structures on a wafer includes: providing a wafer including a substrate, a material layer above the substrate, and an exposed photoresist layer above the material layer; spraying the exposed photoresist layer with a first liquid; spraying the exposed photoresist layer with a second liquid, the second liquid including a developer suitable for the exposed photoresist layer, to obtain a developed photoresist layer; using the developed photoresist layer as a mask, etching the material layer to obtain an etched material layer; and S5: removing the remaining photoresist layer. The method according to the invention overcomes the defect that photoresist polymers on wafers produced in the prior art cannot be completely removed, improving the yield of the produced wafers and reducing manufacturing costs.

Description

Technical Field

[0001] This invention belongs to the field of photolithography in semiconductor manufacturing, and specifically relates to a method for forming patterned structures on wafers. Background Technology

[0002] With the rapid iteration of artificial intelligence and sensor technology, the market demand for power devices and micro-electro-mechanical system (MEMS) chips continues to rise. Functional designs are becoming more diversified, and the requirements for the adaptability of chip processing technology and supporting materials are constantly increasing. Various new materials are gradually revealing many technical problems to be solved during the process of process manufacturing.

[0003] Photolithography is one of the core processes in chip manufacturing. Developer is a common consumable used in wafer fabrication plants, and its formulation and concentration are usually fixed. Currently, the most commonly used developer in the industry is a 2.38% TMAH (tetramethylammonium hydroxide) solution, which is suitable for developing most conventional photoresists.

[0004] However, as application scenarios continue to expand, the differences in substrate materials and photoresist composition in different processes are becoming increasingly prominent. The compatibility issues between photoresist and general-purpose developer are frequent, and photoresist residues are easily formed on the silicon wafer surface, affecting the performance of the final product.

[0005] The current conventional developing process is as follows: after the wafer completes the spin-drying process, the robotic arm that sprays the developer moves the nozzle above the wafer to initiate the developer spraying process. Since all photoresist products on the entire production line use the same concentration of universal developer, polymer residue often remains in a fixed area at the initial developer spraying location when dealing with photoresists with special components or products on special substrates. This residue cannot be removed by conventional parameter optimization methods such as extending the developer rinsing time or adjusting the rinsing pressure. Especially for large-area chip products, this residue severely reduces chip production yield and significantly increases manufacturing costs. Currently, there is no low-cost, effective solution in the industry to overcome this problem.

[0006] There is a need in the art for methods that can improve at least one of the above aspects to reduce photoresist polymer residue. Summary of the Invention

[0007] The present invention is provided to provide a further improved method for forming patterned structures on a wafer while reducing photoresist polymer residue.

[0008] One aspect of the present invention provides a method for forming a patterned structure on a wafer, comprising the following steps: S1. providing a wafer, the wafer including a substrate, a material layer above the substrate, and an exposed photoresist layer above the material layer; S2. spraying the exposed photoresist layer with a first liquid; S3. spraying the exposed photoresist layer with a second liquid, the second liquid including a developer suitable for the exposed photoresist layer, to obtain a developed photoresist layer; S4. using the developed photoresist layer as a mask, etching the material layer to obtain an etched material layer; and S5. removing the remaining photoresist layer.

[0009] In the method described above, the first liquid comprises pure water or a liquid with a concentration lower than that of the developer.

[0010] As described above, the flow rate of the first liquid is less than or equal to the flow rate of the second liquid.

[0011] As described above, S2 includes: S21: spraying the first liquid onto a first position on the exposed photoresist layer; and S3 includes: S31: spraying the second liquid onto the exposed photoresist layer starting from the first position.

[0012] As described above, the duration of S2 is determined based on the type of the first liquid.

[0013] The method described above further includes: S6: spin-drying the wafer, wherein S2 is performed after S6.

[0014] As described above, S2 is performed by the auxiliary contact head, and S3 is performed by the main contact head.

[0015] As described above, the auxiliary contact head is positioned adjacent to the main contact head.

[0016] As described above, the main contact head and the auxiliary contact head are fixed in position relative to each other and are each equipped with an independent liquid pipeline.

[0017] The method described above is used to manufacture power chips.

[0018] The method for forming patterned structures on wafers according to this invention eliminates the problem of polymer residue from photoresist after development, significantly improving wafer yield. In applications where this process is used simultaneously in automotive chips, it eliminates the potential risks caused by unstable quality in automotive chips. Attached Figure Description

[0019] Some embodiments of this disclosure have been described with reference to the accompanying drawings. This description, together with the drawings, makes it apparent to those skilled in the art how some embodiments can be practiced. The drawings are for illustrative purposes and do not attempt to show structural details of the embodiments in more detail than necessary for a basic understanding of this disclosure.

[0020] Figure 1 The diagram illustrates the photoresist polymer residue caused by existing development methods.

[0021] Figure 2 The diagram illustrates a prior art development process.

[0022] Figure 3 The figure shows a schematic diagram of a development process according to some embodiments of the present disclosure.

[0023] Figure 4 This is a flowchart of a method for forming a patterned structure on a wafer according to some embodiments of the present invention.

[0024] Figure 5 This is a flowchart of a first process associated with a method for forming a patterned structure on a wafer, according to some embodiments of the present invention.

[0025] Figure 6 The illustration shows a schematic diagram of the relative positions of the main contact head and the auxiliary contact head according to some embodiments of the present invention.

[0026] Figures 7-13 The illustrations show some embodiments of the invention. Figure 4 The diagram illustrates the various stages of forming a patterned structure using the methods described in the text.

[0027] It will be understood that, for the sake of brevity and clarity, the elements shown in the accompanying drawings are not necessarily drawn to scale. For example, for clarity, the dimensions of some elements may be exaggerated relative to others. Additionally, reference numerals may be repeated between drawings where deemed appropriate to indicate corresponding or similar elements. Detailed Implementation

[0028] Numerous specific details are set forth in the following detailed description in order to provide a thorough understanding of the subject matter of this disclosure. However, those skilled in the art will understand that the subject matter of this disclosure can be practiced without these specific details. In other instances, well-known methods, processes, and components have not been described in detail so as not to obscure the subject matter of this disclosure.

[0029] In the specification and claims of this application, the words “comprising” and “having” and their various forms are not limited to members of the list that may be associated with these words.

[0030] As used herein, the term "about" can be used to specify that the value of a quantity or parameter (e.g., the length of an element) is within a continuous range of values ​​near (and including) a given (specified) value. According to some embodiments, "about" can specify that the value of a parameter is between 80% and 120% of a given value. For example, the statement "the length of the element is approximately 1 m" is equivalent to the statement "the length of the element is between 0.8 m and 1.2 m." According to some embodiments, "about" can specify that the value of a parameter is between 90% and 110% of a given value. According to some embodiments, "about" can specify that the value of a parameter is between 95% and 105% of a given value.

[0031] As used herein, the terms “substantially” and “about” are interchangeable according to some embodiments.

[0032] In this application, ordinal numbers such as "first," "second," and "third" are used to distinguish different instances of objects with the same name. The ordinal numbers "first," "second," and "third" do not indicate a relative order of the indicated objects in time, space, sequence, or other aspects.

[0033] In this application, the term "pure water" refers to water from which suspended solids, colloids, dissolved ionic impurities, microorganisms, and organic impurities have been removed (e.g., EW-I, EW-II, EW-III, or EW-IV electronic grade water that meets the requirements of Electronic Grade Water (EGW) as specified in GB / T 11446.1).

[0034] Figure 1 The diagram illustrates the photoresist polymer residue caused by existing development methods.

[0035] In photolithography, the developer is usually a fixed, universal material used in the factory. However, in some product processes, differences in substrate and photoresist composition can lead to photoresist residue on the silicon wafer during development due to incompatibility issues with the developer. For example... Figure 1 As shown in the image.

[0036] This is because some photoresists react violently with the developer, resulting in an electrostatic adsorption effect on polymers. These residues cannot be removed by increasing the development and rinsing time.

[0037] Accordingly, this invention conceives of a technique to reduce polymer residue on wafer surfaces: by controlling the concentration of the developer, the initial neutralization reaction is made more gentle, reducing the formation of reactants, and the generated static electricity can be quickly eliminated by grounding of the process equipment. This avoids polymer adsorption on the wafer surface due to static electricity and other factors. Then, a large amount of developer is sprayed to complete the pre-designed development process.

[0038] Figure 2 and Figure 3 The diagrams illustrate the development process of the prior art and the development process according to some embodiments of the present disclosure.

[0039] like Figure 2 As shown, the prior art development process involves spraying pure water onto the exposed wafer and then spin-drying it. During the transfer process after exposure, nanoscale particles and residual acidic / alkaline atmosphere impurities from the environment may adhere to the surface of the wafer. Spraying with pure water (e.g., EW-I ultrapure water) followed by spin-drying can remove these impurities in advance, preventing them from reacting with the developer to form insoluble byproducts that adhere to the wafer surface, while also preventing ionic impurities from affecting the concentration uniformity of the developer.

[0040] After exposure, the photoresist (especially the exposed area of ​​positive photoresist) has a certain degree of hydrophilicity. If the pure water is sprayed and then the developer is sprayed directly without being spun dry, the excess pure water remaining on the wafer surface will continue to wet the photoresist, causing the photoresist to swell unexpectedly, or even dissolve and peel off the exposed pattern, ultimately resulting in pattern deformation and linewidth shift after development.

[0041] The spin-drying process, by controlling the rotation speed and time parameters, can retain only a uniform nanoscale hydration layer on the photoresist surface. This achieves the effect of pre-wetting to improve compatibility while avoiding the side effects of excessive pure water. For example, the spin-drying process can typically be set with a rotation speed of about 1000-3000 rpm and a time of about 5-10 seconds, ultimately forming a uniform water film with a thickness of approximately <100 nm on the wafer surface.

[0042] like Figure 2 As shown, the prior art development process includes spraying developer onto the wafer immediately after spin-drying. When the development time reaches the process set value, pure water is sprayed to immediately terminate the development reaction, avoid overdevelopment defects, and rinse away soluble residues and byproducts to obtain a developed wafer.

[0043] like Figure 3 As shown, the development process according to some embodiments of the present invention differs from the prior art in that an additional step of spraying a small amount of pure water or low-concentration developer is added between the spin-drying of the wafer and the spraying of the developer. This step aims to pre-wet the surface of the wafer, reducing the concentration of the photoresist surface in contact with the developer during the spraying process. By controlling the concentration of the developer, gradually increasing it from 0% or a lower concentration to 2.38%, the initial neutralization reaction is made more gentle, preventing polymers from adhering to the wafer surface due to static electricity or other factors.

[0044] It should be noted that it is counterintuitive to spray additional liquid onto a spin-dried wafer before spraying a large amount of developer. Those skilled in the art generally agree that the optimal process route is to spray a standard concentration of developer directly after spin-drying in the developing process to avoid increasing process complexity, reducing unit throughput, or causing a series of process risks such as uneven developing rate, exceeding linewidth tolerance, and photoresist swelling failure.

[0045] However, through extensive process experiments, the inventors discovered that adding the aforementioned pre-wetting step between the spin-drying wafer and the spraying of the developer did not produce the various negative effects commonly expected in the field. On the contrary, by gradually increasing the developer concentration gradient, the problem of intense local reactions and polymer adhesion residues caused by the instantaneous contact of high-concentration developer with photoresist in conventional processes was solved, and it did not affect the linewidth accuracy and uniformity of the pattern after development. This result is different from conventional expectations.

[0046] Furthermore, the inventors discovered through process verification that, although this process adds additional process steps, the yield of wafers manufactured using the method according to embodiments of the present invention is significantly improved, effectively reducing the production costs that would otherwise have been caused by insufficient yield.

[0047] The yield improvement is particularly significant for large-size chips (e.g., power chips). Due to the larger size of individual chips, the number of chips that can be cut from a single wafer is smaller, and the impact of photoresist residue on chip performance will have a more significant impact on the chip yield on the wafer.

[0048] According to one aspect of the present invention, a method for forming patterned structures on a wafer is provided.

[0049] Figure 4 This is a flowchart of a method for forming a patterned structure on a wafer according to some embodiments of the present invention.

[0050] In some examples, the method may include step S1: providing a wafer including a substrate, a material layer above the substrate, and an exposed photoresist layer above the material layer.

[0051] In some examples, the method may include step S2: spraying the exposed photoresist layer with a first liquid.

[0052] In some examples, the method may include step S3: spraying the exposed photoresist layer with a second liquid to obtain a developed photoresist layer. The second liquid may include a developer suitable for the exposed photoresist layer.

[0053] In some examples, the method may include step S4: using the developed photoresist layer as a mask, etching the material layer to obtain the etched material layer.

[0054] In some examples, the method may include step S5: removing the remaining photoresist layer.

[0055] In some examples, the method may optionally further include step S6: spin-drying the wafer. Step S2 may be performed after step S6.

[0056] In some examples, the first liquid may include ultrapure water or a liquid with a concentration lower than that of the developer. In some examples, the flow rate of the first liquid may be less than or equal to the flow rate of the second liquid.

[0057] In some examples, the duration of step S2 can be determined based on the type of the first liquid.

[0058] In some examples, step S2 may be performed by the auxiliary contact head, and step S3 may be performed by the main contact head. In some examples, the auxiliary contact head is positioned adjacent to the main contact head. In some examples, the main contact head and the auxiliary contact head are fixed in position relative to each other and are each equipped with independent fluid lines. The following will combine... Figure 6 Describe the settings for the main contact and auxiliary contact.

[0059] In some examples, this method is used to manufacture power chips.

[0060] The following will combine Figures 7-13 describe Figure 4 Further implementation details of the method.

[0061] Figure 5 This is a flowchart of a first process associated with a method for forming a patterned structure on a wafer, according to some embodiments of the present invention. The first process may be... Figure 4 The specific implementation of steps S2 and S3 in the method is described, but the scope of the present invention is not limited thereto.

[0062] In an embodiment, the first process may include step S21: spraying a first liquid onto a first location on the exposed photoresist layer.

[0063] In an embodiment, the first process may include step S31: spraying the exposed photoresist layer with a second liquid starting from a first position.

[0064] The following will combine Figures 7-13 describe Figure 5 Further implementation details of the first process.

[0065] Figure 6 The illustration shows a schematic diagram of the relative positions of the main contact head and the auxiliary contact head according to some embodiments of the present invention.

[0066] like Figure 6As shown, the developing apparatus according to an embodiment of the present invention may include a main contact head 610 and an adjacent auxiliary contact head 620. The relative positions of the main contact head 610 and the auxiliary contact head 620 are fixed, that is, the distance d between the main contact head 610 and the auxiliary contact head 620 remains constant. By way of example and not limitation, the distance d may be about 1 cm, about 1.5 cm, or about 2 cm.

[0067] The main contact head 610 and the auxiliary contact head 620 are each equipped with their own liquid lines and are used to spray different solutions. By way of example and not limitation, the main contact head 610 may be configured to spray a 2.38% TMAH solution from its liquid line, while the auxiliary contact head 620 may be configured to spray pure water or a TMAH solution with a concentration lower than 2.38% from its liquid line.

[0068] During operation, the main contact head 610 and the auxiliary contact head 620 move together to the target position where development begins. First, the auxiliary contact head 620 sprays pure water or low-concentration developer onto the target position of the spun-dry wafer to pre-wet the wafer surface. Then, the main contact head 610 starts to formally spray the developer from the target position.

[0069] To ensure the quality of the developing process, pre-wetting by the auxiliary contact head 620 should be completed within a short time. The spraying time depends on the properties of the liquid, and the shorter the better. As an example and not a limitation, pre-wetting can be completed within 1 second, depending on the type of liquid.

[0070] The flow rate of the liquid sprayed by the auxiliary contact head 620 should not be too high to avoid affecting the concentration of the subsequent normal developer. The maximum flow rate should not exceed the flow rate of the developer sprayed. As an example and not a limitation, a pre-wetting liquid with a flow rate of 300-500 ml / min can be sprayed by the auxiliary contact head 620, followed by a normal concentration developer with a flow rate of 1000 ml / min sprayed by the main contact head 610.

[0071] After the development process is completed according to the preset development procedure, the main contact head 610 and the auxiliary contact head 620 return to their original positions simultaneously.

[0072] The following is combined Figures 7-13 Specific implementation details of methods and processes according to some embodiments of the present invention are described.

[0073] Figures 7-13 The illustrations show some embodiments of the invention. Figure 4 The diagram illustrates the various stages of forming a patterned structure using the methods described in the text.

[0074] like Figure 7As shown, a wafer is first provided, which may include a substrate 710, a material layer 720 above the substrate, and an exposed photoresist layer 730 above the material layer. The photoresist layer 730 may include exposed areas and unexposed areas.

[0075] Next, as Figure 8 As shown, (for example, by Figure 6 The auxiliary contact 620 (at the target position where development begins) sprays the exposed photoresist layer 730 with an auxiliary liquid. This auxiliary liquid can be, as described above... Figure 4 Examples of the first liquid may be, for example, pure water or a liquid with a concentration lower than that of a conventional developer.

[0076] Subsequently, as Figure 9 As shown, (for example, by Figure 6 Starting from the target position (the main contact 610), the exposed photoresist layer 730 is sprayed with a developer of conventional concentration to obtain the following: Figure 10 The photoresist layer 735 shown is a developed photoresist layer. This conventional concentration developer can be the one described above. Figure 4 Examples of the second liquid, and may be, for example, a 2.38% concentration TMAH liquid.

[0077] After development is complete, such as Figure 11 As shown, using the developed photoresist layer 735 as a mask, the material layer 720 is etched with an etchant or plasma to obtain the desired result. Figure 12 The etched material layer 725 shown is illustrated.

[0078] Finally, the remaining photoresist layer (i.e., the developed photoresist layer 735) is removed to obtain the following: Figure 13 The patterned structure shown includes a substrate 710 and an etched material layer 725.

[0079] The advantage of embodiments of the present invention lies in that, by pre-wetting the wafer with pure water or a low-concentration liquid at the target location where development begins before formal development, the rate of the initial acid-base neutralization reaction is reduced, and the phenomenon of photoresist polymer adsorbing onto the wafer surface due to electrostatic effects is reduced, allowing the photoresist on the wafer to be almost completely removed. The yield of wafers produced using the method according to embodiments of the present invention is increased from about 50% to about 100%.

[0080] It will be understood that, for clarity, certain features of this disclosure described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of this disclosure described in the context of a single embodiment may also be provided individually, or in any suitable sub-combination, or appropriately provided in any other described embodiment of this disclosure. Unless expressly stated otherwise, any feature described in the context of an embodiment should not be considered an essential feature of that embodiment.

[0081] Although the operations of a method may be described in a specific sequence according to some embodiments, the methods of this disclosure may include some or all of the methods performed in a different order. Specifically, it should be understood that the order of operations and sub-operations of any described method may be reordered, for example, when a later operation requires the output of a previous operation as input, or when a later operation requires the product of a previous operation. The methods of this disclosure may include some or all of the described operations. Unless expressly stated otherwise, no particular operation of the disclosed methods should be considered an essential operation of the method.

[0082] Furthermore, the terms “front,” “back,” “top,” “bottom,” “above,” “below,” etc. (if any) used in the specification and claims are for descriptive purposes and are not necessarily used to describe persistent relative positions. It should be understood that such terms are interchangeable where appropriate, such that the embodiments described herein can, for example, operate in orientations other than those illustrated or otherwise described herein.

[0083] Although this disclosure has been described in conjunction with specific embodiments thereof, it will be apparent that numerous alternatives, modifications, and variations are possible and will be obvious to those skilled in the art. Therefore, this disclosure encompasses all such alternatives, modifications, and variations falling within the scope of the appended claims. It should be understood that this disclosure is not necessarily limited in its application to the details of the construction and arrangement of the components and / or methods set forth herein. Other embodiments may also be practiced, and embodiments may be implemented in various ways.

[0084] It will be understood that the wording and terminology used herein are for descriptive purposes and should not be considered restrictive. Therefore, those skilled in the art will understand that the concepts upon which this disclosure is based can serve as the basis for designing other structures, methods, and systems for carrying out the various purposes of this disclosure.

[0085] Those skilled in the art will readily understand that various modifications and changes can be applied to the embodiments of the present disclosure as described above without departing from the scope defined in and by the appended claims.

Claims

1. A method for forming patterned structures on a wafer, characterized in that, Includes the following steps: S1: Provide a wafer, the wafer including a substrate, a material layer above the substrate, and an exposed photoresist layer above the material layer; S2: Spray the exposed photoresist layer with the first liquid; S3: Spray the exposed photoresist layer with a second liquid, the second liquid including a developer suitable for the exposed photoresist layer, to obtain a developed photoresist layer; S4: Using the developed photoresist layer as a mask, etch the material layer to obtain the etched material layer; as well as S5: Remove the remaining photoresist layer.

2. The method according to claim 1, characterized in that, The first liquid includes pure water or a liquid with a concentration lower than that of the developer.

3. The method according to claim 1, characterized in that, The flow rate of the first liquid is less than or equal to the flow rate of the second liquid.

4. The method according to claim 1, characterized in that, S2 includes: S21: Spray the first liquid onto the first position on the exposed photoresist layer; and S3 includes: S31: Spray the exposed photoresist layer with the second liquid starting from the first position.

5. The method according to claim 1, characterized in that, The duration of S2 is determined based on the type of the first liquid.

6. The method according to claim 1, characterized in that, The method further includes: S6: Spin dry the wafer. S2 is executed after S6.

7. The method according to claim 1, characterized in that, S2 is performed by the auxiliary contact head, and S3 is performed by the main contact head.

8. The method according to claim 7, characterized in that, The auxiliary contact head is positioned adjacent to the main contact head.

9. The method according to claim 7, characterized in that, The main contact head and the auxiliary contact head are fixed in position relative to each other and are each equipped with an independent liquid pipeline.

10. The method according to claim 1, characterized in that, The method is used to manufacture power chips.

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