Method for reducing phosphorus precipitation in phosphorosilicate glass, semiconductor device and manufacturing method thereof

Abstract

The invention provides a method for reducing phosphorus precipitation in phosphorosilicate glass, a semiconductor device and a manufacturing method of the semiconductor device, and belongs to the field of semiconductors. The method for reducing phosphorus precipitation in phosphorosilicate glass comprises the following steps: providing a pure silicon dioxide substrate, depositing a phosphorosilicate glass layer on the surface of the pure silicon dioxide substrate to a target thickness in a multi-time circulating deposition mode, and introducing inert gas into the surface of the phosphorosilicate glass layer in a gap between two adjacent phosphorosilicate glass layers deposited, and removing phosphorus-containing gas which is not bonded with the phosphorosilicate glass layer. According to the invention, the phosphorus-containing gas which is not bonded with the phosphorosilicate glass layer is removed, so that the problem of phosphorus precipitation on the phosphorosilicate glass layer can be avoided. And the long-term stability of semiconductor device performance is ensured.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for reducing phosphorus precipitation in phosphosilicate glass, a semiconductor device and a manufacturing method thereof. Background Art

[0002] After the structure of a transistor device is fabricated and before entering the back-end copper process, a pre-metal dielectric (PMD) layer is required to fill the uneven gates and source / drain regions on the surface of the transistor device and flatten the surface, laying the foundation for the planarization of the back-end copper process of the transistor device. A phosphosilicate glass (PSG) thin film is commonly used for PMD. PSG is a phosphosilicate glass doped with P element in undoped silica glass (USG), which has good thermal reflow property and electrical insulation property, can be used as a metal dielectric layer to improve the surface planarization of the thin film and the stability of the integrated circuit. Using PSG as PMD is mainly because the phosphorus in PSG has a certain gettering effect, which can effectively control the impurity content of the transistor device and ensure the working range and stability of the device.

[0003] However, there is unbonded phosphorus in the PSG thin film. The unbonded phosphorus will precipitate, be oxidized by oxygen in the air, and absorb water, and then phosphoric acid is generated, forming protruding defects on the surface of the transistor device, that is, there is a problem of phosphorus precipitation in the unbonded phosphorus. As time goes by, the problem of phosphorus precipitation becomes more serious.

[0004] It should be noted that the information disclosed in the background art part of this invention is only intended to deepen the understanding of the general background art of this invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for reducing phosphorus precipitation in phosphosilicate glass, a semiconductor device and a manufacturing method thereof, so as to solve the problem of phosphorus precipitation in the PSG thin film.

[0006] To solve the above technical problems, the present invention provides a method for reducing phosphorus precipitation in phosphosilicate glass, including:

[0007] Providing a pure silica substrate, depositing a phosphosilicate glass layer on the surface of the pure silica substrate to a target thickness by means of multiple cyclic depositions, and introducing an inert gas to the surface of the phosphosilicate glass layer during the interval between two adjacent depositions of the phosphosilicate glass layer to remove the unbonded phosphorus-containing gas in the phosphosilicate glass layer.

[0008] Preferably, the target thickness of the phosphosilicate glass layer is

[0009] Preferably, the thickness range of each deposited phosphosilicate glass layer is

[0010] Preferably, the flow rate of the inert gas introduced to the surface of the phosphosilicate glass layer is 25 - 40 slm, and the duration is 5 s - 8 s.

[0011] Preferably, the inert gas includes one or any combination of argon, nitrogen, and helium.

[0012] Preferably, the phosphosilicate glass layer is deposited by PECVD process.

[0013] Preferably, the gases for depositing the phosphosilicate glass layer by the PECVD process include silane, phosphine, and oxygen.

[0014] Based on the same inventive concept, the present invention also provides a method for fabricating a semiconductor device, including:

[0015] Providing a semiconductor structure, the surface of which has a pure silicon dioxide layer;

[0016] Depositing a phosphosilicate glass layer on the surface of the pure silicon dioxide layer by the method for reducing the precipitation of phosphorus in the phosphosilicate glass as described above;

[0017] Performing a grinding process on the phosphosilicate glass layer;

[0018] Performing a back-end process on the semiconductor structure after the grinding process.

[0019] Preferably, the target thickness of the phosphosilicate glass layer is

[0020] Based on the same inventive concept, the present invention also provides a semiconductor device, including:

[0021] Fabricated by the method for fabricating a semiconductor device as described above.

[0022] Compared with the prior art, the method for reducing the precipitation of phosphorus in the phosphosilicate glass of the present invention has the following advantages:

[0023] The present invention provides a pure silicon dioxide substrate, and deposits a phosphosilicate glass layer on the surface of the pure silicon dioxide substrate to the target thickness by multiple cyclic depositions, and during the gap between two adjacent depositions of the phosphosilicate glass layer, an inert gas is introduced to the surface of the phosphosilicate glass layer to remove the unbonded phosphorus-containing gas in the phosphosilicate glass layer. By removing the unbonded phosphorus-containing gas in the phosphosilicate glass layer, the problem of phosphorus precipitation in the phosphosilicate glass layer can be avoided. Ensure the long-term stability of the performance of the semiconductor device.

[0024] The method for fabricating a semiconductor device provided by the present invention and the semiconductor device belong to the same inventive concept as the method for reducing the precipitation of phosphorus in phosphosilicate glass provided by the present invention. Therefore, the method for fabricating a semiconductor device and the semiconductor device provided by the present invention at least have all the advantages of the method for reducing the precipitation of phosphorus in phosphosilicate glass provided by the present invention, can avoid the problem of phosphorus precipitation in the semiconductor device, and thus can ensure the long-term stability of the performance of the semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of a PSG layer in an embodiment;

[0026] Figure 2 is a schematic diagram of depositing a PSG layer by a single deposition method in an embodiment;

[0027] Figure 3 is by using Figure 2 the electron scanning image of the PSG layer obtained by the PSG deposition method therein;

[0028] Figure 4 is a flowchart of the method for reducing the precipitation of phosphorus in phosphosilicate glass in an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of a PSG layer in an embodiment of the present invention;

[0030] Figure 6 is a schematic diagram of depositing a PSG layer by a multiple deposition method in an embodiment of the present invention;

[0031] In the figure,

[0032] 100 - semiconductor structure; 200 - pure silicon dioxide layer;

[0033] 300 - PSG layer with a higher phosphorus content; 400 - phosphosilicate glass layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, advantages, and features of the present invention more clear, the following further elaborates in detail on the method for reducing phosphorus precipitation in phosphosilicate glass, the semiconductor device, and its manufacturing method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the objectives of the embodiments of the present invention. It should be understood that the drawings in the specification do not necessarily show the specific structure of the present invention in proportion, and the illustrative features used to explain certain principles of the present invention in the drawings of the specification will also adopt a slightly simplified drawing method. The specific design features of the present invention disclosed herein, such as specific dimensions, directions, positions, and shapes, will be partially determined by the specific application and usage environment. Also, in the embodiments described below, sometimes the same reference numerals are used commonly between different drawings to represent the same part or parts with the same function, and the repeated description thereof is omitted. In this specification, similar reference numerals and letters are used to represent similar items. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0035] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0036] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0037] As shown Figures 1 to 3 in Figure 1 As shown, a PSG layer is deposited on the surface of the semiconductor structure 100 shown as a dielectric layer. The semiconductor structure 100 therein is the transistor device after the structure fabrication is completed. The PSG serves as the dielectric layer to fill the surface of the semiconductor structure 100, laying the foundation for the subsequent copper process fabrication. A pure silicon dioxide layer 200 grows on the surface of the semiconductor structure 100. In the prior art, on the surface of the pure silicon dioxide layer 200,Figure 2 As shown in the schematic diagram, a PSG layer is grown by a single deposition method. The PSG layer is deposited by a single deposition method. The gases for depositing the PSG layer include silane, phosphine, and oxygen. Since chemical reactions cannot ensure that all reactants react completely, the phosphine is in excess, resulting in unbonded phosphorus in the PSG layer. On the surface of the PSG layer 300 with a high phosphorus content, there is a problem of phosphorus precipitation, and protrusion defects such as those indicated by arrow a in Figure 3 are likely to occur on the surface of the PSG layer 300 with a high phosphorus content. These defects affect the subsequent processes of semiconductor devices.

[0038] To solve the problem of phosphorus precipitation, a Chinese invention patent with the publication number CN105226033A discloses an optimization method for a phosphorus-silicon glass passivation film. A silicon nitride film is grown on the surface of the PSG layer by the PECVD method to prevent the PSG surface from deliquescing and reduce the problem of phosphorus precipitation. Although this process can achieve the effect of isolating water vapor, the unbonded phosphorus still exists in the PSG layer, affecting the long-term reliability of the device.

[0039] To solve the problem of phosphorus precipitation, a Chinese patent with the publication number CN03148448.4 discloses a method for improving the interface defects between pure silicon dioxide and phosphorus-silicon glass. When growing the PSG layer, the introduction of PH3 is increased in stages to prevent PH3 from being in excess. Although this method can avoid the excess of PH3, it may lead to uneven phosphorus content in the deposited PSG. When introducing low-concentration PH3, the deposited phosphorus content is relatively low. The phosphorus content affects the etching rate, and the uneven deposition of phosphorus will affect the etching morphology, and there may also be phenomena such as incomplete etching or over-etching. Therefore, the uniformity of the PSG phosphorus content is a very important parameter.

[0040] The core idea of the present invention is to provide a method for reducing phosphorus precipitation in phosphorus-silicon glass, solve the problem of phosphorus precipitation in the PSG layer, and ensure the stability of semiconductor devices.

[0041] To achieve the above idea, the present invention provides a method for reducing phosphorus precipitation in phosphorus-silicon glass, referring to Figures 4 to 6 a specific implementation manner of a method for reducing phosphorus precipitation in phosphorus-silicon glass disclosed. The method for reducing phosphorus precipitation in phosphorus-silicon glass includes the following steps S1 to S3.

[0042] Step S1: Provide a pure silicon dioxide substrate.

[0043] Specifically, referring to Figure 4 and Figure 5As shown, a layer of pure silicon dioxide layer 200 is deposited on the surface of the semiconductor structure 100 as a pure silicon dioxide substrate. The semiconductor structure 100 therein has a gate, as well as a source region and a drain region. The front-end process of the semiconductor structure 100 has been completed.

[0044] Step S2: Deposit a phosphosilicate glass layer 400 on the surface of the pure silicon dioxide substrate to a target thickness by means of multiple cyclic depositions, and introduce an inert gas into the surface of the phosphosilicate glass layer 400 during the interval between two adjacent depositions of the phosphosilicate glass layer 400 to remove the unbonded phosphorus-containing gas in the phosphosilicate glass layer 400.

[0045] Specifically, refer Figures 4 to 6 As shown, a phosphosilicate glass layer 400 is deposited by a plasma-enhanced chemical vapor deposition (PECVD) process. The semiconductor structure 100 with the structure fabrication completed is placed in the machine, and silane (SiH4) gas, phosphine (PH3), and oxygen (O2) are introduced into the machine, and a phosphosilicate glass (PSG) layer 400 is deposited on the surface of the pure silicon dioxide substrate by means of multiple depositions. Refer Figure 6 As shown, after the first deposition of the phosphosilicate glass layer 400 is completed, the first layer of phosphosilicate glass layer is obtained. Then, an inert gas is introduced into the machine to remove the excess unbonded phosphorus on the surface of the first layer of phosphosilicate glass layer. After purging with the inert gas, one cycle of the first layer of phosphosilicate glass is completed. In this embodiment, the target thickness of the phosphosilicate glass layer 400 is Therefore, by using the above method and depositing the phosphosilicate glass layer 400 through multiple cycles. Preferably, the thickness range of each deposition of the phosphosilicate glass layer is That is, the thickness of each deposition of the phosphosilicate glass layer can be Or Any value within the range. In this embodiment, preferably, the thickness of each deposition of the phosphosilicate glass layer is This can prevent the residual unbonded phosphorus caused by the too thick phosphosilicate glass layer deposited each time. And it can also improve the operation efficiency of the machine. That is, the phosphosilicate glass layer 400 with a thickness of can be deposited by adopting a ten-cycle method. During one cycle period, the flow rates of silane (SiH4) gas, phosphine (PH3), and oxygen (O2) introduced into the chamber of the machine are 5 sccm to 10 sccm, and the introduction time is 0.2 to 0.4 min, so that the thickness of the phosphosilicate glass layer 400 deposited in one cycle is The flow rate of the inert gas introduced is 25 to 40 slm, and the duration is 5 s to 8 s. That is, the flow rate of the inert gas introduced can be 25 slm, 30 slm, 35 slm, 40 slm, or any value within the range of 25 to 40 slm. Here, slm is a flow rate unit, indicating the volume flow rate per minute under standard conditions (0 °C, 1 atm). Taking 40 slm as an example, that is, under standard conditions, the volume flow rate per minute is 40. At this flow rate, it is sufficient to carry away the incompletely reacted phosphine gas in the chamber of the machine. At this flow rate, the time for introducing the inert gas can be maintained at 5 seconds (s), 6 s, 7 s, 8 s, or any time within 5 s to 8 s. In this embodiment, preferably, the flow rate of the inert gas introduced is 40 slm, and the time for introducing the inert gas is 8 s. The inert gas includes one or any combination of argon, nitrogen, and helium.

[0046] To implement the above idea, this embodiment also discloses a method for fabricating a semiconductor device, including:

[0047] First, provide a semiconductor structure 100, and the surface of the semiconductor structure 100 has a pure silicon dioxide layer 200.

[0048] Next, deposit a phosphosilicate glass layer 400 on the surface of the pure silicon dioxide layer 200 by using the method for reducing the precipitation of phosphorus in phosphosilicate glass as described above. The target thickness of the phosphosilicate glass layer 400 is Depositing the phosphosilicate glass layer 400 on the surface of the pure silicon dioxide layer 200 by using the method for reducing the precipitation of phosphorus in phosphosilicate glass as described above can avoid the problem of phosphorus precipitation in the phosphosilicate glass layer 400.

[0049] Then, perform a grinding process on the phosphosilicate glass layer 400. By using chemical mechanical polishing (CMP), grind the surface of the phosphosilicate glass layer 400 to planarize the surface of the phosphosilicate glass layer 400.

[0050] Finally, perform back-end process fabrication on the semiconductor structure 100 after the grinding process. For example, perform back-end copper interconnect process and the like on the semiconductor structure 100 after the grinding process.

[0051] To implement the above idea, this embodiment also discloses a semiconductor device, including being fabricated by using the method for fabricating a semiconductor device as described above.

[0052] The semiconductor device manufacturing method and the semiconductor device provided in this embodiment belong to the same inventive concept as the method for reducing phosphorus precipitation in phosphosilicate glass provided in this embodiment. Therefore, the semiconductor device manufacturing method and the semiconductor device provided in this embodiment at least have all the advantages of the method for reducing phosphorus precipitation in phosphosilicate glass provided in this embodiment, and can avoid the problem of phosphorus precipitation in the semiconductor device, thereby ensuring the long-term stability of the performance of the semiconductor device.

[0053] In summary, the above embodiments have described in detail different configurations of the method for reducing phosphorus precipitation in phosphosilicate glass, the semiconductor device, and its manufacturing method. Of course, the above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. The present invention includes but is not limited to the configurations listed in the above embodiments. Those skilled in the art can draw inferences from the content of the above embodiments. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure are within the scope of protection of the claims.

Claims

1. A method for reducing phosphorus precipitation in phosphosilicate glass, characterized in that: include: A pure silicon dioxide substrate is provided, and a phosphosilicate glass layer is deposited on the surface of the pure silicon dioxide substrate to a target thickness by multiple cycles of deposition. In the interval between two adjacent depositions of the phosphosilicate glass layer, an inert gas is introduced into the surface of the phosphosilicate glass layer to remove phosphorus-containing gas that is not bonded to the phosphosilicate glass layer.

2. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 1, characterized in that: The target thickness of the phosphosilicate glass layer is 3. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 1, characterized in that: The thickness of each deposited phosphosilicate glass layer ranges from 4. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 1, characterized in that: The inert gas is introduced into the surface of the phosphosilicate glass layer at a flow rate of 25 to 40 slm for a duration of 5 to 8 seconds.

5. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 1, characterized in that: The inert gas includes one of argon, nitrogen and helium or any combination thereof.

6. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 1, characterized in that: The phosphosilicate glass layer was deposited using a PECVD process.

7. The method for reducing phosphorus precipitation in phosphosilicate glass according to claim 6, characterized in that: The gases used to deposit the phosphosilicate glass layer by the PECVD process include silane, phosphine and oxygen.

8. A method for manufacturing a semiconductor device, characterized in that: include: Providing a semiconductor structure, wherein the surface of the semiconductor structure has a pure silicon dioxide layer; Depositing a phosphosilicate glass layer on the surface of a pure silicon dioxide layer by using the method for reducing phosphorus precipitation in phosphosilicate glass as described in any one of claims 1 to 7; Grinding the phosphosilicate glass layer; The semiconductor structure after grinding is subjected to back-end process manufacturing.

9. The method for manufacturing a semiconductor device according to claim 8, characterized in that: The target thickness of the phosphosilicate glass layer is 10. A semiconductor device, characterized in that: include: The semiconductor device is manufactured using the semiconductor device manufacturing method according to claim 8 or 9.

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