Methods for Improving Defects of Tungsten Metal After Grinding

Abstract

The present invention discloses a method for improving defects in tungsten metal after polishing, comprising the following steps: Step S1, providing a semiconductor integrated process substrate on which tungsten metal is to be deposited; Step S2, performing vapor deposition of tungsten metal on the semiconductor integrated process substrate described in Step S1; Step S3, performing chemical mechanical polishing and planarization on the semiconductor integrated process substrate on which tungsten is deposited; Step S4, performing a low-temperature atmosphere thermal annealing process on the substrate obtained in Step S3; and Step S5, performing subsequent processes. The present invention addresses the defect of tungsten metal easily reacting with water vapor and oxygen to form polymers when exposed to air during semiconductor integrated process manufacturing by performing chemical mechanical polishing and planarization on the deposited tungsten metal and then performing a low-temperature atmosphere thermal annealing process. This method extends process waiting time, facilitates the smooth implementation of subsequent processes, and improves the final performance and yield of the product.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method for improving defects of tungsten metal after grinding. Background Art

[0002] Tungsten has a high melting point (3382°C) and good thermal stability. It has good resistance to electron migration at high current density, does not form hillocks, has low stress, and has a thermal expansion coefficient close to that of silicon. It can form good ohmic contact with silicon and has strong step coverage. Therefore, it is widely used as a contact window, filling metal for via holes, and diffusion barrier layer in the integrated circuit manufacturing process.

[0003] At the same time, tungsten chemical vapor deposition (CVD) has become an important technology in semiconductor processing because the metal tungsten (W) formed has lower resistivity, higher resistance to electromigration, excellent flatness when filling small through-holes, and excellent step coverage compared to tungsten deposited by physical sputtering. In the structure of semiconductor components, tungsten is commonly used as a highly conductive interconnect metal, silicon through-silicon vias (TSVs) between metal layers, vertical contact holes (contacts), and spacers between aluminum and silicon.

[0004] In the integrated circuit manufacturing process, tungsten metal deposition usually requires chemical mechanical polishing to be flattened. The tungsten metal that has been flattened will be exposed to the air before subsequent processes. During this period, water vapor, oxygen, etc. in the air will react with the metal to form some polymers. Existing data shows that such polymer defects are discovered after more than 6 hours, seriously affecting subsequent processes and the final performance and yield of the product. Figure 1 shown. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to solve the problem of polymers generated when the metal tungsten that has been polished and flattened is exposed to the air.

[0006] In order to solve the above technical problems, the method for improving the defects of tungsten metal after grinding of the present invention comprises the following steps:

[0007] Step S1, providing a semiconductor integrated process substrate to be deposited with metal tungsten;

[0008] Step S2, performing tungsten metal vapor deposition on the semiconductor integrated process substrate described in S1;

[0009] Step S3, performing chemical mechanical polishing and planarization treatment on the semiconductor integrated process substrate on which tungsten is deposited;

[0010] Step S4, performing a low-temperature atmosphere thermal annealing process on the substrate obtained in step S3;

[0011] Step S5: perform subsequent processes.

[0012] Preferably, in step S1, the semiconductor integrated process substrate on which metal tungsten is to be deposited is a substrate which has undergone a front-end process to the process step of depositing metal tungsten in the field effect transistor manufacturing process.

[0013] Preferably, the field effect transistor is NMOS or PMOS.

[0014] Preferably, the front-end process includes the following steps:

[0015] Step S11, providing a semiconductor substrate;

[0016] Step S12: forming a gate, a source, and a drain on the semiconductor substrate.

[0017] Preferably, the semiconductor integrated process substrate is Si, SiGe or GaN.

[0018] Preferably, in step S2, the tungsten metal vapor deposition is chemical vapor deposition or physical vapor deposition.

[0019] Preferably, in step S4, the low temperature atmosphere thermal annealing process is performed at a temperature of 300-500° C., a pressure of 1 torr-780 torr, and a time of 10 seconds-1000 seconds.

[0020] Preferably, in step S4, the atmosphere includes nitrogen, hydrogen or a nitrogen-hydrogen mixed gas.

[0021] The present invention performs a low-temperature atmosphere thermal annealing process on the deposited metal tungsten during the semiconductor integrated manufacturing process by chemically mechanically polishing and flattening the deposited metal tungsten. This solves the defect that metal tungsten easily reacts with water vapor and oxygen to form polymers when exposed to air, prolongs the process waiting time, facilitates the smooth implementation of subsequent processes, and improves the final performance and yield of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of polymer defects generated when metal tungsten is exposed to air in the prior art;

[0023] Figure 2 This is a flow chart of the method for improving defects in tungsten metal after grinding according to the present invention;

[0024] Figure 3 This is a defect inspection effect diagram after using the method of improving defects in tungsten metal after grinding of the present invention. DETAILED DESCRIPTION

[0025] The following describes the implementation manner of the present invention through specific specific embodiments. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through different specific implementation manners, and the various details in this specification can also be applied based on different viewpoints, and various modifications or changes can be made without deviating from the overall design concept of the invention. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. The following exemplary embodiments of the present invention can be implemented in a variety of different forms and should not be interpreted as being limited to the specific embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0026] like Figure 2 As shown, the method for improving defects of tungsten metal after grinding of the present invention comprises the following steps:

[0027] Step S1: providing a semiconductor integrated process substrate on which metal tungsten is to be deposited.

[0028] In step S1, the semiconductor integrated process substrate on which the metal tungsten is to be deposited is a substrate that has undergone the front-end process to the process step of depositing the metal tungsten in the field effect transistor manufacturing process. Of course, this method and technology can also be applied to form various types of semiconductor devices (including but not limited to junction field effect transistors (JFETs), diodes, thyristors, vertical field effect transistors, and thyristors).

[0029] The front-end process may include the following steps: Step S11, providing a semiconductor substrate; Step S12, forming a gate, source, and drain on the semiconductor substrate. The field-effect transistor may be an NMOS transistor or a PMOS transistor. Its structure includes a gate, a silicon substrate, and a thin silicon dioxide layer sandwiched between the gate and the silicon substrate.

[0030] Preferably, the semiconductor integrated process substrate may be Si, SiGe or GaN.

[0031] Step S2, performing tungsten metal vapor deposition on the semiconductor integrated process substrate described in S1;

[0032] In this step, the tungsten metal vapor deposition is chemical vapor deposition or physical vapor deposition.

[0033] Typically, tungsten films deposited using chemical vapor deposition (CVD) provide better step coverage and uniformity than those deposited using physical vapor deposition (PVD). During the CVD process, contact windows or intermetallic contact holes are filled, and a layer of tungsten is applied to the wafer surface. The bulk of the tungsten on the wafer surface must be removed, leaving only the tungsten in the contact windows or intermetallic contact holes.

[0034] Step S3, performing chemical mechanical polishing and planarization treatment on the semiconductor integrated process substrate on which tungsten is deposited;

[0035] During the chemical mechanical polishing and planarization process of tungsten, the oxidant will form a layer of solid metal oxide on the tungsten surface to protect the tungsten surface and prevent further oxidation reactions. The mechanical wear of the particles in the polishing slurry will remove the passivated metal oxide and expose the metal surface to repeat the oxidation and oxide removal processes.

[0036] Step S4, performing a low-temperature atmosphere thermal annealing process on the substrate obtained in step S3;

[0037] The low temperature atmosphere thermal annealing process has a temperature of 300-500° C., a pressure of 1 torr-780 torr, a time of 10 seconds-1000 seconds, and an atmosphere including nitrogen, hydrogen, or a nitrogen-hydrogen mixture.

[0038] Step S5: perform subsequent processes.

[0039] Figure 3 The image shows the effect of defect inspection after using the present method for improving tungsten metal post-polishing defects. This method, during the semiconductor integrated manufacturing process, performs chemical mechanical polishing and flattening on the deposited tungsten metal, followed by a low-temperature atmosphere thermal annealing process. This addresses the defect of tungsten metal easily reacting with water vapor and oxygen to form polymers when exposed to air. This extends process waiting time, facilitates the smooth implementation of subsequent processes, and improves the final performance and yield of the product.

[0040] The present invention has been described in detail above by way of specific embodiments and examples, but these do not constitute limitations of the present invention. Without departing from the principles of the present invention, those skilled in the art may make many variations and improvements, which should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving defects in tungsten metal after grinding, characterized in that: The following steps are involved: Step S1, providing a semiconductor integrated process substrate to be deposited with metal tungsten; Step S2, performing tungsten metal vapor deposition on the semiconductor integrated process substrate described in S1; Step S3, performing chemical mechanical polishing and planarization treatment on the semiconductor integrated process substrate on which tungsten is deposited; Step S4, performing a low-temperature atmosphere thermal annealing process on the substrate obtained in step S3; Step S5: performing subsequent processes; In step S4, a low-temperature atmosphere thermal annealing process is performed at a temperature of 300-500° C., a pressure of 1 torr-780 torr, and a time of 10 seconds-1000 seconds to solve the defect that metal tungsten easily reacts with water vapor and oxygen to form polymers when exposed to air.

2. The method for improving defects of tungsten metal after grinding according to claim 1, characterized in that: In step S1, the semiconductor integrated process substrate on which metal tungsten is to be deposited is a substrate that has undergone the front-end process to the process step of depositing metal tungsten in the field effect transistor manufacturing process.

3. The method for improving defects of tungsten metal after grinding according to claim 2, characterized in that: The field effect transistor is NMOS or PMOS.

4. The method for improving defects of tungsten metal after grinding according to claim 2, characterized in that: The front-end process includes the following steps: Step S11, providing a semiconductor substrate; Step S12: forming a gate, a source, and a drain on the semiconductor substrate.

5. The method for improving defects of tungsten metal after grinding according to claim 4, characterized in that: The semiconductor integration process substrate is Si, SiGe or GaN.

6. The method for improving defects of tungsten metal after grinding according to claim 1, characterized in that: In step S2, the tungsten metal vapor deposition is chemical vapor deposition or physical vapor deposition.

7. The method for improving defects of tungsten metal after grinding according to claim 1, characterized in that: In step S4, the atmosphere includes nitrogen, hydrogen, or a nitrogen-hydrogen mixed gas.

Images