Semiconductor structure and method for forming the same

Abstract

A semiconductor structure and a method for forming the same, the method comprising: providing a substrate, the substrate comprising a base and a metal layer located on the surface of the base; forming a dielectric layer and a contact hole located in the dielectric layer on the substrate, the contact hole exposing a portion of the surface of the metal layer; performing a methylation treatment on the surface of the dielectric layer and the sidewall surface of the contact hole; performing a hydrogen plasma treatment on the surface of the metal layer after the methylation treatment; and forming a conductive plug in the contact hole after the hydrogen plasma treatment, wherein the methylation treatment replaces the hydroxyl dangling bonds with methyl bonds, and while removing the hydroxyl dangling bonds, oxygen ions are not introduced, which is beneficial to the selective growth of the conductive plug material on the surface of the metal layer, and a conductive plug material with a lower defect density can be formed, thereby improving the performance of the formed conductive plug and obtaining a conductive plug with a lower resistivity.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a semiconductor structure and a forming method thereof. Background Art

[0002] The contact hole is the connection channel between the device in the chip and the first layer of metal. The connection between different devices is revealed by etching the contact hole and the metal layer. Tungsten is introduced into the manufacturing process of integrated circuits at the submicron level and below as a through-hole filling material. However, as the size of integrated circuit devices continues to shrink, the aspect ratio of contact holes continues to increase, which poses a huge challenge to the existing tungsten filling process. CVD (Chemical Vapor Deposition) has very good step coverage, so it is widely used in the contact hole filling process, but it faces the problem of high resistance of the conductive plug formed.

[0003] The resistance of the conductive plug will affect the speed of the chip, so effectively reducing the resistance of the conductive plug has become an important issue in advanced semiconductor manufacturing processes. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a semiconductor structure and a method for forming the same, so as to improve the performance of the semiconductor structure.

[0005] In order to solve the above technical problems, the technical solution of the present invention provides a semiconductor structure, including: a substrate, the substrate including a base and a metal layer located on the surface of the base; a dielectric layer located on the substrate and a contact hole in the dielectric layer, the contact hole exposing a portion of the surface of the metal layer; methyl bonds located on the surface of the dielectric layer and the sidewall surface of the contact hole; and a conductive plug located in the contact hole.

[0006] Optionally, the method further includes: an etch stop layer located between the dielectric layer and the substrate.

[0007] Correspondingly, the technical solution of the present invention also provides a method for forming the above-mentioned semiconductor structure, comprising: providing a substrate, the substrate comprising a base, and a metal layer located on the surface of the base; forming a dielectric layer and a contact hole located in the dielectric layer on the substrate, the contact hole exposing a portion of the surface of the metal layer; performing methylation treatment on the surface of the dielectric layer and the side wall surface of the contact hole; after the methylation treatment, performing hydrogen plasma treatment on the surface of the metal layer; after the hydrogen plasma treatment, forming a conductive plug in the contact hole.

[0008] Optionally, the methylation treatment process includes a dry treatment process or a wet treatment process.

[0009] Optionally, the dry treatment process includes a plasma treatment process, and the process parameters of the plasma treatment process include: the plasma gas used includes straight-chain alkane.

[0010] Optionally, process parameters of the hydrogen plasma treatment process include: an energy range of 50 watts to 500 watts, and a temperature range of 50 degrees Celsius to 600 degrees Celsius.

[0011] Optionally, the method for forming the contact hole includes: forming a dielectric material layer on the surface of the substrate; forming a patterned layer on the surface of the dielectric material layer, wherein the patterned layer exposes a portion of the dielectric material layer on the metal layer; etching the dielectric material layer using the patterned layer as a mask until the metal layer is exposed, thereby forming the dielectric layer and the contact hole located in the dielectric layer.

[0012] Optionally, the dielectric material layer and the substrate surface further have an etch stop material layer, and the process for forming the contact hole further includes: the etch stop material layer is etched to form an etch stop layer, and the contact hole is also located in the etch stop layer.

[0013] Optionally, the material of the etch stop layer includes a combination of one or more of silicon nitride, silicon oxynitride, aluminum nitride and nitrogen-doped carbon.

[0014] Optionally, the thickness of the etch stop layer ranges from 50 angstroms to 400 angstroms.

[0015] Optionally, the process for forming the conductive plug includes a selective deposition process.

[0016] Optionally, the process parameters for forming the conductive plug include: a flow ratio of tungsten hexafluoride to hydrogen ranging from 1 / 20 to 1 / 150, a temperature ranging from 200 degrees Celsius to 600 degrees Celsius, and a pressure ranging from 5 Torr to 400 Torr.

[0017] Optionally, the material of the conductive plug includes tungsten.

[0018] Optionally, the material of the dielectric layer includes silicon oxide.

[0019] Optionally, after forming the contact hole and before the methylation treatment, the contact hole and the surface of the dielectric layer are cleaned.

[0020] Optionally, the material of the metal layer includes cobalt, tungsten or copper.

[0021] Optionally, the depth of the contact hole in a direction perpendicular to the substrate surface ranges from 100 angstroms to 800 angstroms; and the size of the contact hole in a direction parallel to the substrate surface ranges from 10 nanometers to 50 nanometers.

[0022] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0023] In the method for forming a semiconductor structure provided by the technical solution of the present invention, the surface of the dielectric layer and the surface of the side wall of the contact hole are subjected to methylation treatment. After the methylation treatment, the surface of the metal layer is subjected to hydrogen plasma treatment. The hydrogen plasma treatment can remove the oxide layer on the surface of the metal layer. Compared with the oxygen plasma treatment on the surface of the dielectric layer, the methylation treatment replaces the hydroxyl dangling bonds with methyl bonds (-CH3). While removing the hydroxyl dangling bonds, no oxygen ions are introduced. Therefore, the hydrogen plasma treatment process will not introduce hydroxyl dangling bonds again, thereby not causing the subsequent growth of conductive plug materials on the side walls of the contact holes and the surface of the dielectric layer. That is, it is beneficial to the selective growth of conductive plug materials on the surface of the metal layer, and conductive plug materials with lower defect density can be formed, thereby improving the performance of the formed conductive plug and obtaining a conductive plug with lower resistivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figures 1 to 5 It is a cross-sectional schematic diagram of the formation process of a semiconductor structure;

[0025] Figures 6 to 10 It is a cross-sectional schematic diagram of the semiconductor structure forming process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] As described in the background art, the method for forming a conductive plug in the prior art needs to be improved.

[0027] Figures 1 to 4 It is a cross-sectional schematic diagram of the semiconductor structure formation process.

[0028] Please refer to Figure 1 , providing a substrate 100, wherein the substrate 100 includes a base 101 and a metal layer 102 located on the surface of the base; forming a dielectric layer 103 and a contact hole 104 located in the dielectric layer 103 on the substrate 100, wherein the contact hole 104 exposes a portion of the surface of the metal layer 102; and cleaning the surface of the substrate 100.

[0029] Please refer to Figure 2 , oxygen plasma treatment is performed on the surface of the dielectric layer 103 and the side wall surface of the contact hole 104 to remove hydroxyl groups a (—OH) on the surface of the dielectric layer 103 and the side wall of the contact hole 104 .

[0030] Please refer to Figure 3 After the oxygen plasma treatment, the surface of the dielectric layer 103 and the side wall surface of the contact hole 104 are treated with hydrogen plasma.

[0031] Please refer to Figure 4 or Figure 5 After the hydrogen plasma treatment, a conductive plug 105 is formed in the contact hole 104 .

[0032] In the above method, the conductive plug 105 is formed. When the hydroxyl groups on the surface of the dielectric layer 103 and the sidewall of the contact hole 104 are completely removed, the conductive plug 105 material can be selectively grown on the surface of the metal layer 102, thereby forming a conductive plug 105. Figure 4 However, in the method, after the surface of the substrate 100 is cleaned, the surface of the dielectric layer 103 and the sidewall of the contact hole 104 have a large number of hydroxyl groups a (such as Figure 1 As shown), by oxygen plasma treatment, the hydroxyl a is greatly reduced (as shown Figure 2 As shown), the oxygen plasma treatment forms a metal oxide layer 105 on the surface of the exposed metal layer 102, and the hydrogen plasma treatment is used to remove the metal oxide layer 105. However, the hydrogen plasma treatment increases the amount of hydroxyl a (as shown). Figure 3 As shown in FIG. 1 ). The hydroxyl group a will become the nucleation site for the growth of the conductive plug 106 material. A large amount of hydroxyl group a may even cause the selective growth of the conductive plug 106 material on the surface of the metal layer 102 to fail, forming a structure as shown in FIG. Figure 5 The conductive plug 106 shown. Some hydroxyl groups a (such as Figure 3 The hydroxyl group a) at the position I shown in the figure will form a defect b (such as Figure 5 As shown in FIG. 1 , the formed conductive plug 106 has a high degree of defects, resulting in an increase in the resistivity of the conductive plug 106 and a decrease in the electrical performance of the conductive plug.

[0033] In order to solve the above problems, the present invention provides a method for forming a semiconductor structure, wherein the surface of the dielectric layer and the surface of the side wall of the contact hole are methylated. After the methylation, the surface of the metal layer is treated with hydrogen plasma. The hydrogen plasma treatment can remove the oxide layer on the surface of the metal layer. Compared with the oxygen plasma treatment on the surface of the dielectric layer, the methylation treatment replaces the hydroxyl dangling bonds with methyl bonds (-CH3). While removing the hydroxyl dangling bonds, no oxygen ions are introduced. Therefore, the hydrogen plasma treatment process will not introduce hydroxyl dangling bonds again, thereby not causing the subsequent growth of conductive plug materials on the side walls of the contact hole and the surface of the dielectric layer. That is, it is beneficial to the selective growth of conductive plug materials on the surface of the metal layer, and conductive plug materials with lower defect density can be formed, thereby improving the performance of the formed conductive plug and obtaining a conductive plug with lower resistivity.

[0034] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] Figures 6 to 10 It is a cross-sectional schematic diagram of the semiconductor structure forming process according to an embodiment of the present invention.

[0036] Please refer to Figure 6 , providing a substrate 200 , wherein the substrate 200 includes a base 201 and a metal layer 202 located on a surface of the base 201 .

[0037] The substrate 200 may be single crystal silicon, polycrystalline silicon or amorphous silicon, or may be a semiconductor material such as silicon, germanium, silicon germanium, gallium arsenide, or may be an insulating dielectric material such as silicon oxide, silicon nitride, silicon carbide, silicon oxycarbide, silicon oxynitride, etc. The substrate 200 may be a single-layer structure, or a composite structure, such as a device (such as a transistor) may be formed in the substrate; or the substrate may be an insulating dielectric layer, and a connection line connected to a transistor may be provided in the substrate, and the metal layer may be located on the top surface of the connection line.

[0038] In this embodiment, the material of the metal layer 202 is cobalt. In other embodiments, the material of the metal layer 202 can be copper, tungsten or other metals.

[0039] Please refer to Figure 7 A dielectric layer 203 and a contact hole 204 located in the dielectric layer 203 are formed on the substrate 200 , and the contact hole 204 exposes a portion of the surface of the metal layer 202 .

[0040] The material of the dielectric layer 203 includes silicon oxide. In this embodiment, the material of the dielectric layer 203 is silicon oxide. In other embodiments, the material of the dielectric layer 203 includes one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon carbonitride and silicon carbon oxynitride.

[0041] The process for forming the dielectric layer 203 includes a chemical vapor deposition process. In this embodiment, the process for forming the dielectric layer 203 is a high-density plasma chemical vapor deposition process.

[0042] The process of forming the contact hole 204 includes a dry etching process.

[0043] The depth of the contact hole 204 in a direction perpendicular to the surface of the substrate 200 ranges from 100 angstroms to 800 angstroms; the size of the contact hole 204 in a direction parallel to the surface of the substrate 200 ranges from 10 nanometers to 50 nanometers.

[0044] The method for forming the contact hole 204 includes: forming a dielectric material layer (not marked in the figure) on the surface of the substrate 200; forming a patterned layer (not marked in the figure) on the surface of the dielectric material layer, wherein the patterned layer exposes a portion of the dielectric material layer on the metal layer 202; etching the dielectric material layer using the patterned layer as a mask until the metal layer 202 is exposed, thereby forming the dielectric layer 203 and the contact hole 204 located in the dielectric layer 203.

[0045] In this embodiment, the dielectric material layer and the surface of the substrate 200 also have an etch stop material layer (not marked in the figure), and the formation process of the contact hole 204 also includes: the etch stop material layer is etched to form an etch stop layer 205, and the contact hole 204 is also located in the etch stop layer 205.

[0046] The material of the etch stop layer 205 includes one or more combinations of silicon nitride, silicon oxynitride, aluminum nitride and nitrogen-doped carbon. In this embodiment, the material of the etch stop layer 205 is silicon nitride.

[0047] The thickness of the etch stop layer 205 ranges from 50 angstroms to 400 angstroms.

[0048] Subsequently, a methylation treatment is performed on the surface of the dielectric layer 203 and the sidewall surface of the contact hole 204 .

[0049] In this embodiment, after forming the contact hole 204 and before the methylation treatment, the contact hole 204 and the surface of the dielectric layer 203 are cleaned. The cleaning process is used to obtain a clean surface, which is conducive to the subsequent formation of a low-defect conductive plug in the contact hole 204.

[0050] However, when the dielectric layer 203 and the contact hole 204 are exposed to air, a large number of hydroxyl (-OH) dangling bonds c are formed on the sidewalls of the contact hole 204 and the surface of the dielectric layer 203. In the subsequent formation process of the conductive plug, the hydroxyl dangling bonds c will cause the growth of the conductive plug material on the surface of the dielectric layer 203 and the sidewalls of the contact hole 204, which is not conducive to the formation of the conductive plug. In order to selectively grow the conductive plug material on the metal layer 202, the surface of the dielectric layer 203 and the sidewall surface of the contact hole 204 are subsequently methylated.

[0051] Since the metal layer 202 is exposed to air, a metal oxide layer 206 is easily formed on the surface of the metal layer 202. Subsequently, before forming a conductive plug in the contact hole 204, the metal oxide layer 206 needs to be removed to reduce the contact resistance between the conductive plug and the metal layer 202.

[0052] Please refer to Figure 8 , the surface of the dielectric layer 203 and the side wall surface of the contact hole 204 are methylated.

[0053] The methylation treatment process includes a dry treatment process or a wet treatment process.

[0054] The dry treatment process includes a plasma treatment process, and the process parameters of the plasma treatment process include: the plasma gas used includes a straight-chain alkane. The chemical formula of the straight-chain alkane is C n H 2n+2 (n<10), including gases such as methane, ethane, etc. In this embodiment, the methylation process adopts a dry process, and the plasma gas used is methane.

[0055] The wet treatment process includes: using a trimethylmethoxysilane solution. Trimethylmethoxysilane can react with hydroxyl dangling bonds to form methyl bonds.

[0056] The methylation treatment replaces the hydroxyl dangling bond c with a methyl bond d (-CH3), and while removing the hydroxyl dangling bond c, no oxygen ions are introduced. Subsequently, the surface of the dielectric layer 203 and the side wall surface of the contact hole 204 are treated with hydrogen plasma to remove the metal oxide layer 206. Since the methylation treatment does not introduce oxygen ions on the surface of the dielectric layer 203 and the surface of the contact hole 204, the hydrogen plasma treatment process will not introduce hydroxyl dangling bonds again, thereby not causing the subsequent growth of conductive plug materials on the side walls of the contact holes and the surface of the dielectric layer, which is beneficial to the selective growth of conductive plug materials on the surface of the metal layer, and can form conductive plug materials with lower defect density, thereby improving the performance of the formed conductive plug and obtaining a conductive plug with lower resistivity.

[0057] Please refer to Fig. 9 After the methylation treatment, the surface of the metal layer 202 is subjected to hydrogen plasma treatment.

[0058] The process parameters of the hydrogen plasma treatment process include: an energy range of 50 watts to 500 watts, and a temperature range of 50 degrees Celsius to 600 degrees Celsius.

[0059] The hydrogen plasma treatment is used to remove the metal oxide layer 206 on the surface of the metal layer 202. After the plasma treatment, a large number of methyl bonds d exist on the surface of the dielectric layer 203 and the sidewall surface of the contact hole 204.

[0060] Please refer to Fig.10 After the hydrogen plasma treatment, a conductive plug 206 is formed in the contact hole 204 .

[0061] The method for forming the conductive plug 206 includes: forming a conductive plug material (not shown in the figure) in the contact hole 204, filling the contact hole 204 with the conductive plug material, and planarizing the conductive plug material until the surface of the dielectric layer 203 is exposed.

[0062] The process parameters for forming the conductive plug 206 include: a flow ratio of tungsten hexafluoride to hydrogen ranging from 1 / 20 to 1 / 150, a temperature ranging from 200 degrees Celsius to 600 degrees Celsius, and a pressure ranging from 5 Torr to 400 Torr.

[0063] The conductive plug 206 is made of tungsten.

[0064] The formation process of the conductive plug 206 includes a selective deposition process. The selective deposition process is advantageous for forming a conductive plug 206 with low defects and reducing the contact resistance between the conductive plug 206 and the metal layer 202 .

[0065] Accordingly, an embodiment of the present invention further provides a semiconductor structure formed by the above method, please continue to refer to Fig.10 , comprising: a substrate 200, the substrate 200 comprising a base 201, and a metal layer 202 located on the surface of the base 201; a dielectric layer 203 located on the substrate 200 and a contact hole 204 (such as Fig. 9 As shown), the contact hole 204 exposes a portion of the surface of the metal layer 202; methyl bonds located on the surface of the dielectric layer 203 and the sidewall surface of the contact hole 204; and a conductive plug 207 located in the contact hole 204.

[0066] In this embodiment, the semiconductor structure further includes: an etch stop layer 205 located between the dielectric layer 203 and the substrate 200 .

[0067] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: Providing a substrate, the substrate comprising a base, and a metal layer located on a surface of the base; Forming a dielectric layer and a contact hole in the dielectric layer on the substrate, wherein the contact hole exposes a portion of the surface of the metal layer, and the sidewall of the contact hole and the surface of the dielectric layer have hydroxyl dangling bonds; Methylation treatment is performed on the surface of the dielectric layer and the surface of the sidewall of the contact hole, wherein the methylation treatment process includes a dry treatment process, wherein the dry treatment process includes a plasma treatment process, and the process parameters of the plasma treatment process include: the plasma gas used includes a straight-chain alkane, and the methylation treatment replaces the hydroxyl dangling bond with a methyl bond, and while removing the hydroxyl dangling bond, no oxygen ions are introduced; After the methylation treatment, the surface of the metal layer is subjected to hydrogen plasma treatment; After the hydrogen plasma treatment, a conductive plug is formed in the contact hole.

2. The method for forming a semiconductor structure according to claim 1, wherein: The process parameters of the hydrogen plasma treatment process include: an energy range of 50 watts to 500 watts, and a temperature range of 50 degrees Celsius to 600 degrees Celsius.

3. The method for forming a semiconductor structure according to claim 1, wherein: The method for forming the contact hole includes: forming a dielectric material layer on the surface of the substrate; forming a patterned layer on the surface of the dielectric material layer, wherein the patterned layer exposes a portion of the dielectric material layer on the metal layer; etching the dielectric material layer using the patterned layer as a mask until the metal layer is exposed, thereby forming the dielectric layer and the contact hole located in the dielectric layer.

4. The method for forming a semiconductor structure according to claim 3, wherein: The dielectric material layer and the substrate surface also have an etch stop material layer, and the process for forming the contact hole further includes: the etch stop material layer is etched to form an etch stop layer, and the contact hole is also located in the etch stop layer.

5. The method for forming a semiconductor structure according to claim 4, wherein: The material of the etch stop layer includes a combination of one or more of silicon nitride, silicon nitride oxide, aluminum nitride and nitrogen-doped carbon.

6. The method for forming a semiconductor structure according to claim 4, wherein: The thickness of the etch stop layer ranges from 50 angstroms to 400 angstroms.

7. The method for forming a semiconductor structure according to claim 1, wherein: The formation process of the conductive plug includes a selective deposition process.

8. The method for forming a semiconductor structure according to claim 7, wherein: The process parameters for forming the conductive plug include: a flow ratio of tungsten hexafluoride to hydrogen ranging from 1 / 20 to 1 / 150, a temperature ranging from 200 degrees Celsius to 600 degrees Celsius, and a pressure ranging from 5 torr to 400 torr.

9. The method for forming a semiconductor structure according to claim 1, wherein: The material of the conductive plug includes tungsten.

10. The method for forming a semiconductor structure according to claim 1, wherein: The material of the dielectric layer includes silicon oxide.

11. The method for forming a semiconductor structure according to claim 1, wherein: After forming the contact hole and before the methylation treatment, the contact hole and the surface of the dielectric layer are cleaned.

12. The method for forming a semiconductor structure according to claim 1, wherein: The material of the metal layer includes cobalt, tungsten or copper.

13. The method for forming a semiconductor structure according to claim 1, wherein: The depth of the contact hole in a direction perpendicular to the substrate surface ranges from 100 angstroms to 800 angstroms; the size of the contact hole in a direction parallel to the substrate surface ranges from 10 nanometers to 50 nanometers.

14. A semiconductor structure formed by the forming method according to any one of claims 1 to 13, characterized in that: include: A substrate, comprising a base and a metal layer located on a surface of the base; A dielectric layer located on the substrate and a contact hole in the dielectric layer, wherein the contact hole exposes a portion of the surface of the metal layer; Plasmonized methyl bonds located on the surface of the dielectric layer and the surface of the sidewall of the contact hole; A conductive plug is located in the contact hole.

15. The semiconductor structure according to claim 14, wherein: Also includes: An etch stop layer is located between the dielectric layer and the substrate.

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