Titanium nitride film growth method and growth machine

Abstract

The invention provides a titanium nitride film growth method and a growth machine, and the growth method comprises the steps: S1, depositing a titanium nitride film with a set thickness H0 on the surface of a wafer, and then carrying out the impurity removal and repair; s2, the step S1 is repeated until the deposition thickness of the titanium nitride thin film is the thickness H; h is greater than H0. According to the invention, the grown titanium nitride film has fewer impurities, and the bulk resistance is reduced.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, and particularly relates to a method and apparatus for growing titanium nitride thin films. Background Technology

[0002] Titanium nitride crystals belong to the cubic crystal system, with a face-centered cubic structure and a lattice constant a = 0.42173 nm. Titanium nitride thin films possess excellent mechanical, thermal, electrical, and corrosion-resistant properties. Due to their high hardness and low coefficient of friction, they are widely used as wear-resistant modification layers for molds, cutting tools, etc. Because of their good wear resistance, corrosion resistance, high melting point, and good high-temperature stability, they are also widely used in aerospace components such as aircraft and rockets. Due to their good electrical and thermal conductivity, they are commonly used as barrier layers in the microelectronics field. With the continuous development of science and technology, thin film materials are increasingly widely used in optics, electronics, energy, and other fields. As an important functional thin film material, titanium nitride thin films possess excellent optical properties, electrical properties, and chemical stability, and are widely used in solar cells, optical coatings, microelectronic devices, and other fields.

[0003] In existing technologies, wafers are transferred to the process chamber via a transfer chamber, and process gases are introduced into the deposition chamber to carry out a reaction, thereby depositing titanium nitride. There are two reaction principles: one is CVD (chemical vapor deposition) and the other is ALD (atomic layer deposition). Figure 1 This is a simplified illustration; actual equipment may differ slightly. The dashed lines represent the wafer transport path.

[0004] Figure 1 In this context, Load lock refers to the transfer bay; Load port refers to the wafer loader; and EFEM refers to the front-end module of the equipment, which is used for the automated transfer of wafers between the wafer pod (FOUP) and the transfer bay (Load lock).

[0005] Typically, one or more of the following gases are introduced into the process chamber to grow titanium nitride: TiCl4, NH3, NF3, SiH4, HCl / O2. After setting the process formula, the titanium nitride (TiN) growth is completed, and then the wafer is returned to the FOUP wafer cassette.

[0006] Traditional methods for preparing titanium nitride thin films suffer from drawbacks such as high impurities and high bulk resistivity. Therefore, finding a way to grow titanium nitride thin films that address these issues has become a pressing technical challenge for those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method and apparatus for growing titanium nitride thin films, resulting in titanium nitride thin films with fewer impurities and lower bulk resistivity. The technical solution adopted is as follows: A method for growing titanium nitride thin films includes the following steps: Step S1: After depositing a titanium nitride thin film of a set thickness H0 on the surface of the wafer, impurity removal and repair are then performed; Step S2: Repeat step S1 until the titanium nitride film has a deposition thickness of H; H > H0.

[0008] Preferably, the procedure specifically includes the following steps: Step 1: The wafer undergoes a deposition process in the deposition process chamber 1, and then the wafer in the deposition process chamber 1 is transferred to the impurity removal chamber 3, where the wafer undergoes a impurity removal process. Step 2: Transfer the wafer from the impurity removal cavity 3 to the deposition process cavity 1; Step 3: The wafer is deposited in the deposition process chamber 1, and then the wafer in the deposition process chamber 1 is transferred to the impurity removal chamber 3. The wafer is then removed in the impurity removal chamber 3. Finally, the thickness of the titanium nitride film is measured. Step 4: If the thickness of the titanium nitride film reaches thickness H, proceed to step 6; otherwise, proceed to step 5. Step 5: Repeat steps 2-3; Step 6: Transfer the wafer in the impurity removal cavity 3 to the transfer cavity 2.

[0009] A titanium nitride thin film growth apparatus for realizing a titanium nitride thin film growth method, comprising: Deposition process chamber 1 is used to deposit a titanium nitride thin film on the surface of the wafer; Impurity removal chamber 3 is used for impurity removal and repair of titanium nitride films; And a transfer cavity 2, which is equipped with a transfer robot. The transfer robot is used to transfer wafers between the deposition process cavity 1 and the impurity removal cavity 3, and to transfer wafers in the impurity removal cavity 3 to the transfer cavity 2. The number of times the wafer is transferred between the deposition process chamber 1 and the impurity removal chamber 3 is N, where N≥2; Among them, the deposition process chamber 1, the impurity removal chamber 3, and the transfer chamber 2 are all vacuum chambers; The deposition process chamber 1, the impurity removal chamber 3, and the transfer chamber 2 are all equipped with transfer windows for the transfer robot to pass through.

[0010] Preferably, the transfer cavity 2 shares side A with the deposition process cavity 1, and the transfer cavity 2 shares side B with the impurity removal cavity 3; The transmission window is opened on both side A and side B; Each transmission window is equipped with a sealing plate, which can move relative to the corresponding transmission window.

[0011] Preferably, in the deposition process and the impurity removal process, the transfer windows on the transfer chamber 2 and the deposition process chamber 1 are closed.

[0012] Preferably, the transfer window is provided on the side C of the impurity removal cavity 3, and the transfer robot transfers the wafer in the impurity removal cavity 3 to the transfer chamber Load lock through the transfer window on the side C; In the deposition and impurity removal processes, the transfer window on side C is closed.

[0013] Preferably, it further includes a cooling device that is moved to fit against the outer wall of the transfer chamber 2 after deposition is completed and before the vacuum is broken.

[0014] Compared with the prior art, the advantages of the present invention are: In the existing technology, titanium nitride deposition process will have a certain amount of impurities, such as residual Cl (the residual Cl will cause high volume resistivity). Titanium nitride will also have N deficiency during the deposition process. In addition, crystal structure abnormalities may occasionally occur during the deposition process of titanium nitride. Once the entire titanium nitride deposition is completed, it is difficult to remove the internal impurities and repair the crystal lattice.

[0015] The present invention first deposits a certain thickness, then removes impurities and repairs it, and then returns it to the process chamber for deposition, followed by another removal of impurities and repair. The deposition and removal steps are repeated until the predetermined titanium nitride thickness is reached, thereby obtaining a high-quality titanium nitride film with lower bulk resistance, fewer impurities, and a smoother surface.

[0016] Based on the measured data, the bulk resistance can be reduced by more than 50%, and the Cl impurity can be reduced by more than 1%. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a titanium nitride thin film growth machine in the prior art; Figure 2 This is a schematic diagram of the structure of the titanium nitride thin film growth machine of the present invention.

[0018] Among them, 1-deposition process chamber, 2-transfer chamber, 3-impurity removal chamber. Detailed Implementation

[0019] The titanium nitride thin film growth method and growth apparatus of the present invention will be described in more detail below with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0020] like Figure 2 As shown, a titanium nitride thin film growth apparatus includes: Deposition process chamber 1 is used to deposit a titanium nitride thin film on the surface of the wafer; Impurity removal chamber 3 is used for impurity removal and repair of titanium nitride films using XPS; And a transfer cavity 2, which is equipped with a transfer robot. The transfer robot transfers wafers between the deposition process cavity 1 and the impurity removal cavity 3, and transfers wafers from the impurity removal cavity 3 to the deposition process cavity 1. The number of times the wafer is transferred between deposition process cavity 1 and impurity removal cavity 3 is N, where N≥2; Among them, deposition process chamber 1, impurity removal chamber 3 and transfer chamber 2 are all vacuum chambers; The deposition process chamber 1, the impurity removal chamber 3, and the transfer chamber 2 are all equipped with transfer windows for the transfer robot to pass through.

[0021] Regarding "number of transfers": transferring a wafer from the deposition process chamber 1 to the impurity removal chamber 3 is counted as 1 transfer; transferring a wafer from the impurity removal chamber 3 to the deposition process chamber 1 is also counted as 1 transfer.

[0022] Specifically, the transfer chamber 2 shares side A with the deposition process chamber 1, and the transfer chamber 2 shares side B with the impurity removal chamber 3; Transmission windows are opened on both side A and side B; Each transmission window is equipped with a cover plate, which can move relative to the corresponding transmission window. The movement of the cover plate relative to the corresponding transmission window is existing technology.

[0023] When the cover plate is attached to the transmission window, the transmission window is in a closed state; when the cover plate is separated from the transmission window, the transmission window is in an open state.

[0024] exist Figure 2 In the middle, the transmission window and the cover plate are not displayed.

[0025] During the deposition and impurity removal processes, the transfer windows on the transfer chamber 2 and the deposition process chamber 1 are closed.

[0026] A transfer window is opened on the side C of the impurity removal cavity 3. The transfer robot transfers the wafer in the impurity removal cavity 3 to the transfer chamber Load lock through the transfer window on the side C. In the deposition and impurity removal processes, the transfer window on side C is closed.

[0027] In this embodiment, a cooling device is further included, which is moved to fit against the outer wall of the transfer chamber 2 after deposition is completed and before the vacuum is broken.

[0028] In summary, regarding this machine: Because the conditions for deposition and impurity removal processes differ significantly, two different chambers are usually required to complete the process.

[0029] Deposition and impurity removal are generally high-temperature processes, and the wafer needs to be repeatedly transferred between two cavities. In order to avoid high-temperature oxidation of titanium nitride, a vacuum transfer cavity is required to remove oxygen.

[0030] The ratio of the number of deposition process chambers to the impurity removal and repair chambers depends on the proportion of process time.

[0031] To prevent oxidation of the deposited titanium nitride, the wafer is usually cooled before the vacuum is broken after deposition, and the equipment needs to be equipped with a cooling chamber or cooling device.

[0032] The deposition chamber 1, the impurity removal chamber 3, and the transfer chamber 2 are all in a vacuum state. The vacuum level of the deposition chamber 1 and the impurity removal chamber 2 is determined by their respective processes. The transfer chamber 3 is used to avoid oxidation during wafer transfer.

[0033] The wafer trays in deposition chamber 1 and impurity removal chamber 3 are both at high temperatures. The temperature of the wafer trays is determined by their respective process temperatures. For example, the temperature of the wafer tray in deposition chamber 1 is 475°C, and the temperature of the wafer tray in impurity removal chamber 3 is 600°C.

[0034] A method for growing titanium nitride thin films includes the following steps: Step S1: After depositing a titanium nitride thin film of a set thickness H0 on the surface of the wafer, impurity removal and repair are then performed; Step S2: Repeat step S1 until the titanium nitride film has a deposition thickness of H; H > H0.

[0035] Specifically, the following steps are included: Step 1: The wafer undergoes a deposition process in the deposition process chamber 1, and then the wafer in the deposition process chamber 1 is transferred to the impurity removal chamber 3, where the wafer undergoes a impurity removal process. Step 2: Transfer the wafer from the impurity removal cavity 3 to the deposition process cavity 1; Step 3: The wafer is deposited in the deposition process chamber 1, and then the wafer in the deposition process chamber 1 is transferred to the impurity removal chamber 3. The wafer is then removed in the impurity removal chamber 3. Finally, the thickness of the titanium nitride film is measured by optical measurement or SEM measurement. Step 4: If the thickness of the titanium nitride film reaches thickness H, proceed to step 6; otherwise, proceed to step 5. Step 5: Repeat steps 2-3; Step 6: Transfer the wafer in the impurity removal cavity 3 to the transfer cavity 2.

[0036] Example 1 The target thickness for titanium nitride deposition is 10 nm.

[0037] First, the wafer is deposited with 5nm in deposition chamber 1 (the deposition rate is known before deposition), and then it enters the high-temperature purification chamber through the vacuum transfer chamber for 5 minutes of high-temperature plasma purification. The sample is then transferred to deposition chamber 1 for 5nm titanium nitride deposition. Next, it is transferred to the high-temperature purification chamber via the vacuum transfer chamber for 5 minutes of high-temperature plasma purification. Then it is sent back to the wafer pod FOUP.

[0038] Example 2 The target thickness for titanium nitride deposition is 100 nm.

[0039] First, after the wafer is deposited with 10nm (the deposition rate before deposition is known), it enters the high-temperature purification chamber through the vacuum transfer chamber and undergoes 5 minutes of high-temperature plasma purification. The sample is then transferred to the deposition chamber for 10nm titanium nitride deposition. Next, it is transferred to the high-temperature purification chamber via the vacuum transfer chamber for 5 minutes of high-temperature plasma purification. Repeat the above steps until the 100nm titanium nitride deposition and impurity removal are completed; Then it is sent back to the wafer box.

[0040] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for growing titanium nitride thin films, characterized in that, Includes the following steps: Step S1: After depositing a titanium nitride thin film of a set thickness H0 on the surface of the wafer, impurity removal and repair are then performed; Step S2: Repeat step S1 until the titanium nitride film has a deposition thickness of H; H > H0.

2. The method for growing titanium nitride thin films according to claim 1, characterized in that, Specifically, the following steps are included: Step 1: The wafer is deposited in the deposition process chamber (1), and then the wafer in the deposition process chamber (1) is transferred to the impurity removal chamber (3), where the wafer is removed. Step 2: Transfer the wafer in the impurity removal cavity (3) to the deposition process cavity (1); Step 3: The wafer is deposited in the deposition process chamber (1), and then the wafer in the deposition process chamber (1) is transferred to the impurity removal chamber (3). The wafer is then removed in the impurity removal chamber (3), and finally the thickness of the titanium nitride film is measured. Step 4: If the thickness of the titanium nitride film reaches thickness H, proceed to step 6; otherwise, proceed to step 5. Step 5: Repeat steps 2-3; Step 6: Transfer the wafer in the impurity removal cavity (3) to the transfer cavity (2).

3. A titanium nitride thin film growth apparatus for implementing the titanium nitride thin film growth method according to any one of claims 1 to 2, characterized in that, include: Deposition process cavity (1) is used to deposit titanium nitride thin film on the surface of wafer; Impurity removal cavity (3) is used for impurity removal and repair of titanium nitride films; The transfer cavity (2) is equipped with a transfer robot, which is used to transfer wafers between the deposition process cavity (1) and the impurity removal cavity (3) and to transfer wafers in the impurity removal cavity (3) to the transfer cavity (2). The number of times the wafer is transferred between the deposition process cavity (1) and the impurity removal cavity (3) is N, where N≥2; The deposition process chamber (1), the impurity removal chamber (3), and the transfer chamber (2) are all vacuum chambers; The deposition process chamber (1), the impurity removal chamber (3), and the transfer chamber (2) are all provided with transfer windows for the transfer robot to pass through.

4. The titanium nitride thin film growth apparatus according to claim 3, characterized in that, The transfer chamber (2) shares side A with the deposition process chamber (1), and the transfer chamber (2) shares side B with the impurity removal chamber (3); The transmission window is opened on both side A and side B; Each transmission window is equipped with a sealing plate, which can move relative to the corresponding transmission window.

5. The titanium nitride thin film growth apparatus according to claim 4, characterized in that, In the deposition and impurity removal processes, the transfer windows on the transfer chamber (2) and the deposition process chamber (1) are closed.

6. The titanium nitride thin film growth apparatus according to claim 4, characterized in that, The transfer window is opened on the side C of the impurity removal cavity (3), and the transfer robot transfers the wafer in the impurity removal cavity (3) to the transfer chamber Load lock through the transfer window on the side C; In the deposition and impurity removal processes, the transfer window on side C is closed.

7. The titanium nitride thin film growth apparatus according to claim 2, characterized in that, Further includes a cooling device that is moved to fit against the outer wall of the transfer chamber (2) after deposition is completed and before the vacuum is broken.

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