Chemical mechanical polishing method of semiconductor wafer and semiconductor device

Abstract

The invention provides a chemical mechanical grinding method of a semiconductor wafer and a semiconductor device, the grinding method comprises at least one sub-grinding step, and the sub-grinding step comprises the following steps: carrying out chemical mechanical grinding on a to-be-ground surface of the semiconductor wafer; cleaning the semiconductor wafer by adopting a cleaning process after grinding; drying the surface of the semiconductor wafer; the cleaning process comprises the following steps: washing the surface of the semiconductor wafer by using an O3 / H2O2 solution, and generating a layer of oxidation film on the surface of the semiconductor wafer through the oxidation effect of O3. The chemical grinding method comprises the following steps: washing the chemically ground surface of the semiconductor wafer by using an O3 / H2O2 solution, generating a layer of oxide film on the surface of the semiconductor wafer through the oxidation effect of O3, and obtaining a required structure through multiple times of chemical mechanical grinding, so that the defects generated in the whole chemical mechanical grinding process are improved, and the quality of the semiconductor wafer is improved. And the performance and the yield of semiconductor products are improved.

Description

Technical Field

[0001] The present invention relates to the technical field related to semiconductor devices, and in particular to a chemical mechanical polishing method for semiconductor wafers and a semiconductor device. Background Art

[0002] Controlling defects in the ALCMP process is the key to affecting the performance of high-k metal gate (HKMG) devices and yield. Therefore, controlling defects in the ALCMP process is a key factor in improving the yield of semiconductor devices, especially controlling micro scratches and damage. In the existing chemical polishing process, after the grinding disc completes the grinding, the top aluminum film cannot be protected when it is cleaned with deionized water. At this time, when it is transferred to the next grinding disc and the cleaning chamber (Cleaner Chamber) for cleaning, scratches and damage are easily formed. How to optimize the above chemical polishing process to reduce the defects caused by grinding and improve product performance and yield is a technical problem that needs to be solved urgently in this field.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to those skilled in the art. Summary of the invention

[0004] In view of the problems in the prior art, the purpose of the present invention is to provide a chemical mechanical polishing method for semiconductor wafers and a semiconductor device. The chemical mechanical polishing method uses an O3 / H2O2 solution in a surface cleaning process after chemical polishing of the semiconductor wafer to generate an oxide film on the surface of the semiconductor wafer, thereby reducing the generation of defects during the polishing process and improving product performance and yield.

[0005] Specifically, a first aspect of the present invention provides a chemical mechanical polishing method for a semiconductor wafer, the polishing method comprising at least one sub-polishing step, the sub-polishing step comprising:

[0006] Chemical mechanical polishing of the surface to be polished of a semiconductor wafer;

[0007] After grinding, a cleaning process is used to clean the semiconductor wafer;

[0008] drying the surface of the semiconductor wafer;

[0009] The cleaning process comprises:

[0010] The surface of the semiconductor wafer is rinsed with an O3 / H2O2 solution, and an oxide film is formed on the surface of the semiconductor wafer through the oxidation effect of O3.

[0011] According to a first aspect of the present invention, the surface to be polished of the chemical mechanical polishing semiconductor wafer is an aluminum film layer.

[0012] According to the first aspect of the present invention, the concentration of O3 in the O3 / H2O2 solution is between 30 ppm and 80 ppm.

[0013] According to the first aspect of the present invention, the time for rinsing the surface of the semiconductor wafer with the O3 / H2O2 solution is 1 to 10 minutes.

[0014] According to the first aspect of the present invention, the cleaning process further comprises, before the step of using the O3 / H2O2 solution to rinse the surface of the semiconductor wafer, using deionized water to clean the semiconductor wafer after chemical mechanical polishing.

[0015] According to the first aspect of the present invention, the grinding method comprises a plurality of the sub-grinding steps.

[0016] According to the first aspect of the present invention, the thickness of the surface of the chemically mechanically polished semiconductor wafer in the latter sub-polishing step is smaller than the thickness of the surface of the chemically mechanically polished semiconductor wafer in the former sub-polishing step.

[0017] A second aspect of the present invention provides a semiconductor device, the semiconductor device comprising an aluminum film layer, the aluminum film layer being obtained by the chemical mechanical polishing method of the semiconductor wafer.

[0018] According to a second aspect of the present invention, the semiconductor device comprises NMOS transistors and PMOS transistors arranged in an array;

[0019] The aluminum film layer is a P-type metal gate of a PMOS transistor.

[0020] According to a second aspect of the present invention, the grinding method comprises a first sub-grinding step, a second sub-grinding step and a third sub-grinding step;

[0021] In the first sub-polishing step, the thickness of the surface to be polished of the chemically mechanically polished semiconductor wafer is 2500 angstroms to 3500 angstroms;

[0022] In the second sub-polishing step, the thickness of the surface to be polished of the chemically mechanically polished semiconductor wafer is 400 angstroms to 600 angstroms.

[0023] Compared with the prior art, the chemical polishing method of the present invention includes using an O3 / H2O2 solution to rinse the surface of the semiconductor wafer after chemical polishing, generating an oxide film on the surface of the semiconductor wafer through the oxidation action of O3, and obtaining the desired structure through multiple chemical mechanical polishing, thereby improving the defects generated in the entire chemical mechanical polishing process and improving the performance and yield of semiconductor products. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present invention will become more apparent. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same figure numbers in the figures represent the same or similar parts, and their repeated descriptions will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0025] Figure 1 A flowchart of a sub-polishing step of a chemical mechanical polishing method for a semiconductor wafer according to an embodiment of the present invention; and

[0026] Figure 2 A schematic structural diagram of a semiconductor device according to an embodiment of the present invention;

[0027] Figures 3 to 5 The chemical mechanical polishing method of the semiconductor wafer according to an embodiment of the present invention is used to polish Figure 2 The semiconductor device of the embodiment is a schematic diagram of the structure after various steps. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in the present invention. The present invention can also be implemented or applied through other different specific embodiments, and the details in the present invention can also be modified or changed according to different viewpoints and application systems without departing from the spirit of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0029] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0030] In the representation of the present invention, the reference terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics represented in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics represented may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples represented in the present invention and the features of different embodiments or examples, unless they are contradictory.

[0031] In order to clearly describe the present invention, components not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0032] Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" by placing other elements therebetween. In addition, when a device is said to "include" a certain component, unless otherwise stated, it does not exclude other components, but means that other components may be included.

[0033] When a device is said to be "on" another device, it may be directly on the other device, but there may also be other devices between it. In contrast, when a device is said to be "directly" on another device, there are no other devices between it.

[0034] Although the terms first, second, etc. are used to represent various elements in some examples, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first interface and the second interface, etc. are represented. Moreover, as used in this article, the singular forms "one", "one" and "the" are intended to also include plural forms, unless there is an opposite indication in the context. It should be further understood that the terms "comprising" and "including" indicate the existence of features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the existence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Only when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way, will there be an exception to this definition.

[0035] The technical terms used herein are only used to refer to specific embodiments and are not intended to limit the present invention. The singular form used herein also includes the plural form as long as the sentence does not clearly indicate the opposite meaning. The meaning of "including" used in the specification is to specify specific characteristics, regions, integers, steps, operations, elements and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements and / or components.

[0036] Although not defined differently, all terms, including technical and scientific terms used herein, have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with the content of relevant technical literature and current disclosures, and unless defined, shall not be overly interpreted as ideal or very formal meanings.

[0037] In order to overcome the above technical problems, the present invention provides a chemical mechanical polishing method for semiconductor wafers and a semiconductor device, the polishing method includes at least one sub-polishing step, the sub-polishing step includes: chemical mechanical polishing the surface to be polished of the semiconductor wafer; cleaning the semiconductor wafer with a cleaning process after polishing; drying the surface of the semiconductor wafer. The cleaning process step: using an O3 / H2O2 solution to rinse the surface of the semiconductor wafer, and generating an oxide film on the surface of the semiconductor wafer through the oxidation effect of O3. The chemical polishing method of the present invention includes using an O3 / H2O2 solution to rinse the surface of the semiconductor wafer, and generating an oxide film on the surface of the semiconductor wafer through the oxidation effect of O3, and obtaining the desired structure through multiple chemical mechanical polishing, thereby improving the defects generated in the entire chemical mechanical polishing process and improving the performance and yield of semiconductor products.

[0038] The chemical mechanical polishing method for semiconductor wafers and the semiconductor device of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments. It can be understood that the various specific embodiments are not intended to limit the protection scope of the present invention.

[0039] In the chemical mechanical polishing process, a polishing head is often used to clamp the semiconductor wafer to be polished and contact it with the polishing pad and perform relative movement for chemical mechanical polishing. The polishing of the p-type metal gate in the semiconductor device is taken as an example below. The p-type metal gate can be an aluminum film layer. In an embodiment, the chemical mechanical polishing equipment can be provided with multiple polishing pads, and the chemical mechanical polishing of the aluminum film layer can be divided into multiple sub-polishing steps. After the semiconductor wafer is polished to a certain thickness on the polishing pad at one position, the surface is cleaned, and the polishing head clamps the semiconductor wafer to be polished to the polishing pad at another position for further polishing, that is, the polishing process of the aluminum film layer includes the switching of the polishing head on the polishing pads at different positions.

[0040] Figure 1The present invention is a flow chart of the sub-polishing steps of the chemical mechanical polishing method of a semiconductor wafer according to an embodiment of the present invention. Specifically, the polishing method includes the following sub-polishing steps:

[0041] Step S100: chemically mechanically polishing the surface to be polished of the semiconductor wafer; preferably, the surface to be polished of the semiconductor wafer to be polished by chemical mechanical polishing is an aluminum film layer;

[0042] Step S200: cleaning the semiconductor wafer using a cleaning process after grinding;

[0043] Step S300: drying the surface of the semiconductor wafer.

[0044] The cleaning process of step S200 includes:

[0045] S210: Use O3 / H2O2 solution to rinse the surface of the semiconductor wafer, and form an oxide film on the surface of the semiconductor wafer through the oxidation effect of O3. In the O3 / H2O2 cleaning process, O3 (ozone) and H2O2 (hydrogen peroxide) are both strong oxidants. The atoms on the surface of the semiconductor wafer are in a higher energy state and have higher activity. O3 / H2O2 will undergo an oxidation reaction with the metal atoms on the surface of the cleaned material (taking metal materials as an example). In addition, there may be some microscopic defects on the surface of the semiconductor wafer, such as lattice vacancies and dislocations. The atoms in these places are more likely to contact and react with the oxidant, thereby promoting the formation of an oxide film. For example, for an aluminum (Al) thin film layer, ozone and hydrogen peroxide will react with aluminum atoms, and the aluminum atoms will lose electrons and become aluminum ions (Al 3+ ), while the oxygen atoms in the solution gain electrons and combine with metal ions to form metal oxides. The reaction formula can be simply expressed as:

[0046] 4Al+3O3+3H2O2=2Al2O3+3H2O+3O2;

[0047] Among them, Al2O3 is the oxide film formed.

[0048] The structure of the formed oxide film can be dense, and the oxide film with a dense structure can effectively prevent oxygen, moisture, etc. from further contacting the metal substrate, thereby playing a protective role.

[0049] At the same time, in the process of using O3 / H2O2 solution to rinse the surface of the semiconductor wafer, organic pollutants can be decomposed by oxidation, and converted into small molecules that are easily soluble in water, thereby achieving the purpose of cleaning the surface of the semiconductor wafer. At the same time, there is a synergistic effect when the O3 / H2O2 mixed solution is used. Hydrogen peroxide can be used as an initiator for ozone decomposition, accelerating ozone decomposition to produce more hydroxyl radicals (·OH). Hydroxyl radicals are highly active oxidants with an oxidation potential of up to 2.80V, second only to fluorine (2.87V). They can react rapidly with most organic matter without selection, making the cleaning effect better. That is, O3 / H2O2 solution cleaning can effectively remove these pollutants while forming an oxide film, and will not damage the surface of the silicon wafer.

[0050] In the O3 / H2O2 cleaning process of step S200, the appropriate O3 and H2O2 concentrations are crucial to the structure (density, etc.) of the generated oxide film and the cleaning effect. When the O3 concentration is high, more ozone molecules can undergo oxidation reactions with the material surface. Ozone molecules have a delocalized π bond, and the oxidation state of the central oxygen atom is +0. This structure makes ozone have a strong tendency to gain electrons and easily obtain electrons from the surface atoms of the material. High concentrations of O3 will accelerate the oxidation process of metal atoms (such as aluminum atoms), prompting the surface to form a metal oxide (such as Al2O3) film faster. As the O3 concentration increases, the rate of the oxidation reaction accelerates, and the thickness of the generated oxide film may increase. However, when the O3 concentration is too high, it may cause uneven growth of the oxide film, because the violent oxidation reaction may cause the local temperature of the material surface to be too high, affecting the crystallization process of the oxide film, and may also cause over-oxidation, making the oxide film structure loose. Preferably, the concentration of O3 in the O3 / H2O2 solution of step S200 is between 30ppm and 80ppm.

[0051] Similarly, a suitable H2O2 concentration contributes to the uniform formation of the oxide film. H2O2 can decompose in the solution to produce hydroxyl radicals (·OH). Hydroxyl radicals are highly active oxidants. When the H2O2 concentration increases, the number of hydroxyl radicals produced increases, and these free radicals participate in the oxidation reaction on the surface of the material. When the H2O2 concentration is too high, the large number of free radicals produced by its decomposition may etch the oxide film that has been formed, destroying the integrity of the oxide film. Excessively high concentrations of H2O2 may cause tiny holes in the oxide film, affecting the quality of the oxide film. Preferably, the volume fraction of hydrogen peroxide in the O3 / H2O2 solution of step S200 may be between 1% and 10%.

[0052] When the cleaning begins, O3 / H2O2 reacts with the surface of the semiconductor wafer to form an oxidation reaction. In a short period of time (e.g., the first few minutes), an oxide film begins to form. As the cleaning time increases, the growth rate of the oxide film gradually changes until the growth of the oxide film reaches an equilibrium state. Preferably, the time for the O3 / H2O2 solution to rinse the surface of the semiconductor wafer is 1 to 10 minutes.

[0053] Of course, the reaction conditions such as the temperature and pH value of the O3 / H2O2 solution will also affect the formation process of the oxide. Generally, as the temperature rises, the rate at which H2O2 decomposes to produce hydroxyl radicals accelerates, and more active oxygen species participate in the oxidation reaction, thereby accelerating the growth of the oxide film. However, too high a temperature may cause the oxide film to grow too fast and cause quality problems. Preferably, the temperature of the O3 / H2O2 solution in step S200 is between 30°C and 40°C. Similarly, the pH value of the solution will affect the stability and oxidizability of O3 and H2O2. Under acidic conditions, the oxidizability of H2O2 is relatively strong because the acidic environment is conducive to the decomposition of hydrogen peroxide to produce more active oxygen species. For example, in the acidic range of pH 3-5, the decomposition reaction of H2O2 will accelerate, thereby promoting the growth of the oxide film. In an alkaline environment, the stability of ozone will decrease, the decomposition rate will accelerate, and more active oxygen will be provided to participate in the oxidation reaction. However, if the pH value is too high, the oxide film formed on the surface of some metal materials may be dissolved by alkali, thereby affecting the growth of the oxide film. For amphoteric metals such as aluminum, a pH value of around 9-11 may be more conducive to the formation of an oxide film with good protective properties. Taking aluminum as an example, the aluminum oxide film formed in an alkaline solution has a relatively stable structure and can effectively improve the corrosion resistance of aluminum.

[0054] The cleaning process of step S200 also includes step S201 before the step of using O3 / H2O2 solution to rinse the surface of the semiconductor wafer in step S210. Step S201 is to use deionized water to clean the semiconductor wafer after chemical mechanical polishing.

[0055] In practice, the grinding method of the present invention includes multiple sub-grinding steps, and the thickness of the surface of the chemically mechanically polished semiconductor wafer in the latter sub-grinding step is less than the thickness of the surface of the chemically mechanically polished semiconductor wafer in the previous sub-grinding step, which is further explained below.

[0056] In high-k / metal gate (HKMG) technology, Al film (aluminum film) is mainly used for metal interconnection or as a part of metal gate structure. In the integrated circuit manufacturing process, the quality and characteristics of the Al film have an important impact on the performance of the entire device. In a multi-layer metal interconnection structure, when the aluminum film is used as the interconnection material, the chemical mechanical polishing method of the present invention is particularly suitable for achieving planarization between different metal layers.

[0057] The present invention also provides a semiconductor device, which comprises an aluminum film layer, and the aluminum film layer is obtained by using the chemical mechanical grinding method of the semiconductor wafer. Figure 2 The structure diagram of a semiconductor device of an embodiment of the present invention; specifically, the semiconductor device may include an NMOS transistor and a PMOS transistor arranged in an array, that is, the semiconductor device is a complementary metal oxide semiconductor device. After depositing multiple layers of materials (such as a metal layer, a dielectric layer, etc.) on the complementary metal oxide semiconductor device, the aluminum film layer 10 is a P-type metal gate of the PMOS transistor, and the surface of the wafer will be uneven. The grinding method of the semiconductor device includes a first sub-grinding step, a second sub-grinding step, and a third sub-grinding step; the above three sub-grinding steps all include the above steps S100 to S300, and the cleaning process in step S200 uses O3 / H2O2 solution to rinse the surface of the semiconductor wafer, and a layer of oxide film is generated on the surface of the semiconductor wafer through the oxidation of O3. The difference is that the process of chemical mechanical grinding of the surface to be ground of the semiconductor wafer in step S100 of the three sub-grinding steps is slightly different, such as the pressure of the grinding head, the roughness of the grinding pad, the rotation speed of the grinding pad, the composition or ratio of the grinding liquid, the grinding time and other parameters are different, so as to control the thickness of the chemical mechanical grinding. In one embodiment, the thickness of the surface of the semiconductor wafer to be polished by chemical mechanical polishing in the first sub-polishing step is 2500 angstroms to 3500 angstroms, and the thickness of the surface of the semiconductor wafer to be polished by chemical mechanical polishing in the second sub-polishing step is 400 angstroms to 600 angstroms. Figure 2 The aluminum film layer 10 to be ground, after the first sub-grinding step, Figure 3 The thickness of the aluminum film layer 11 to be ground is reduced by 3000 angstroms; after the second sub-grinding step, compared with Figure 3 The aluminum film layer to be ground 11, Figure 4 The thickness of the aluminum film layer 12 to be ground is reduced by 500 angstroms; finally, after the third sub-grinding step, Figure 5 semiconductor devices.

[0058] In summary, the chemical polishing method of the present invention uses O3 / H2O2 solution to rinse the surface of the semiconductor wafer after chemical polishing, generates an oxide film on the surface of the semiconductor wafer through the oxidation action of O3, and obtains the desired structure through multiple chemical mechanical polishing, thereby improving the defects generated in the entire chemical mechanical polishing process, and ultimately improving the performance and yield of the prepared semiconductor devices.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0060] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A chemical mechanical polishing method for a semiconductor wafer, characterized in that: The grinding method comprises at least one sub-grinding step, wherein the sub-grinding step comprises: Chemical mechanical polishing of the surface to be polished of semiconductor wafers; After grinding, a cleaning process is used to clean the semiconductor wafer; drying the surface of the semiconductor wafer; The cleaning process comprises: The surface of the semiconductor wafer is rinsed with an O3 / H2O2 solution, and an oxide film is formed on the surface of the semiconductor wafer through the oxidation effect of O3.

2. The chemical mechanical polishing method for a semiconductor wafer according to claim 1, characterized in that: The surface to be polished of the semiconductor wafer in chemical mechanical polishing is an aluminum film layer.

3. The chemical mechanical polishing method for a semiconductor wafer according to claim 1, characterized in that: The concentration of O3 in the O3 / H2O2 solution is between 30 ppm and 80 ppm.

4. The chemical mechanical polishing method for a semiconductor wafer according to claim 1, wherein: The time for rinsing the surface of the semiconductor wafer with the O3 / H2O2 solution is 1 to 10 minutes.

5. The chemical mechanical polishing method for a semiconductor wafer according to claim 1, characterized in that: The cleaning process also includes using deionized water to clean the semiconductor wafer after chemical mechanical polishing before the step of using the O3 / H2O2 solution to rinse the surface of the semiconductor wafer.

6. The chemical mechanical polishing method for a semiconductor wafer according to claim 1, wherein: The grinding method includes a plurality of sub-grinding steps.

7. The chemical mechanical polishing method for a semiconductor wafer according to claim 6, characterized in that: The thickness of the surface of the semiconductor wafer chemically and mechanically polished in the latter sub-polishing step is smaller than the thickness of the surface of the semiconductor wafer chemically and mechanically polished in the former sub-polishing step.

8. A semiconductor device, characterized in that: The semiconductor device comprises an aluminum film layer, and the aluminum film layer is obtained by the chemical mechanical polishing method of the semiconductor wafer according to any one of claims 1 to 7.

9. The semiconductor device according to claim 8, characterized in that The semiconductor device includes NMOS transistors and PMOS transistors arranged in an array; The aluminum film layer is a P-type metal gate of a PMOS transistor.

10. The semiconductor device according to claim 9, characterized in that The grinding method comprises a first sub-grinding step, a second sub-grinding step and a third sub-grinding step; In the first sub-polishing step, the thickness of the surface to be polished of the chemically mechanically polished semiconductor wafer is 2500 angstroms to 3500 angstroms; In the second sub-polishing step, the thickness of the surface to be polished of the chemically mechanically polished semiconductor wafer is 400 angstroms to 600 angstroms.

Images