A method for reworking a MIM upper plate

Abstract

The application provides a rework method of MIM upper plate, comprising the following steps: providing a MIM structure whose upper plate needs to be reworked, the upper plate is a TiN layer, and a dielectric layer is formed below the upper plate; removing the TiN layer by APM wet etching; firstly performing dry etching on the dielectric layer, and then performing wet cleaning twice; again firstly performing dry etching on the dielectric layer, and then performing wet cleaning twice; performing film thickness detection and defect detection; in response to the film thickness detection and the defect detection passing, regrowing the dielectric layer and the TiN layer; performing a subsequent process flow, and performing WAT testing after the completion. The application is used for reworking a wafer when the MIM upper plate is abnormal, the upper plate is etched by wet etching, the dielectric layer is etched by dry etching and wet etching for multiple times, the dielectric layer and the upper plate are regrown after the film thickness detection and the defect detection both pass, the problem of the abnormal MIM upper plate is solved, the rework success rate is increased, and the device yield is improved.

Description

Technical Field

[0001] This invention relates to semiconductor material growth and related processing technologies in the field of semiconductor integrated circuit manufacturing, specifically to a rework method for the upper electrode plate of a MIM (Metal Injection Molding). Background Technology

[0002] Capacitors are commonly used passive components and are widely used in various chips as an important part of integrated circuits. Capacitor structures in integrated circuit chips include MIM (metal-insulator-metal) capacitors, PIP (poly-insulator-polysilicon) capacitors, and MOM (metal-oxide-metal) capacitors.

[0003] MIM capacitors consist of a lower plate, an upper plate, and a dielectric layer between the upper and lower plates, and can be fabricated during the BEOL (Back End of Line) process. During the fabrication of the upper plate, excessive consumption of the sputtered TIN target leads to changes in the grown film quality, causing instability in Rs uniformity and triggering an EPD (End Point Detection) alarm during MIM_ET. Summary of the Invention

[0004] In view of this, the present invention proposes a rework method for the upper electrode plate of MIM to solve the problem of abnormal upper electrode plate of MIM.

[0005] This invention provides a method for reworking the upper electrode plate of a MIM (Metal Injection Molding) system, comprising the following steps:

[0006] Step 1: Provide the MIM structure for which the upper electrode plate needs to be reworked. The upper electrode plate is a TiN layer, and a dielectric layer is formed below the upper electrode plate.

[0007] Step 2: Remove the TIN layer using APM wet etching;

[0008] Step 3: First, perform dry etching on the dielectric layer, and then perform two wet cleaning processes;

[0009] Step 4: Perform dry etching on the dielectric layer again, followed by two wet cleaning processes;

[0010] Step 5: Conduct defect detection;

[0011] Step 6: In response to the defect detection passing, the dielectric layer and the TiN layer are regrown to form;

[0012] Step 7: Proceed with the subsequent process flow and conduct WAT testing upon completion.

[0013] Preferably, the dielectric layer in step one is a SiN layer.

[0014] Preferably, the solution used for the APM wet etching is a mixture of NH4OH, H2O2 and H2O, the temperature is 55°C, and the etching rate is greater than 30A.

[0015] Preferably, the composition ratio of the solution is NH4OH:H2O2:H2O = 1:1:5.

[0016] Preferably, the step after step two and before step three includes: measuring the film thickness of the dielectric layer.

[0017] Preferably, the dry etching conditions in steps three and four are as follows: CH2F2 / Ar / O2 is used as the etching gas, wherein the gas flow rate of CH2F2 is 5-100 sccm, the gas flow rate of Ar is 10-500 sccm, the gas flow rate of O2 is 5-100 sccm, the temperature is 20-100℃, and the RF power is 100-1000W.

[0018] Preferably, the wet cleaning treatment in steps three and four uses ACT940 solution.

[0019] Preferably, in step six, passing the film thickness test means that the film thickness is zero, and passing the defect test means that there are no pits or polymers.

[0020] Preferably, the method further includes: in response to the WAT test passing, rework is successful.

[0021] This invention addresses the rework of MIM structures where the upper electrode plate requires rework. First, the upper electrode plate undergoes wet etching. Then, the dielectric layer is subjected to one dry etching and two wet etching processes. This process is repeated once more. After passing film thickness and defect detection, the dielectric layer and upper electrode plate are regrown for subsequent processing steps. Finally, a WAT ​​test is performed. This invention enables the rework of the MIM upper electrode plate, resolving the issue of MIM upper electrode plate abnormalities and reducing losses. Attached Figure Description

[0022] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0023] Figure 1 The flowchart shown is a rework method for the upper electrode plate of the MIM according to an embodiment of the present invention;

[0024] Figure 2 The diagram shown is a flowchart of a rework method for the upper electrode plate of the MIM according to an embodiment of the present invention. Detailed Implementation

[0025] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0026] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0027] Unless the context explicitly requires it, words such as "including" or "contains" throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to".

[0028] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0029] For cases of abnormal upper electrode plates in MIM (Metal Injection Molding), the solution is to remove the upper electrode plate TIN and the intermediate dielectric layer SIN, and then regenerate the intermediate dielectric layer and the upper electrode plate. Specifically, there are various combinations of methods for removing the upper electrode plate TIN and the intermediate dielectric layer SIN, especially for etching the upper electrode plate TIN, which can be achieved through CMP (Chemical Motion Processing), dry etching, and wet etching. Through various combined experiments, it was found that CMP, a mechanical smoothing method, causes damage, ultimately resulting in pits on the surface after removal; dry etching results in poor uniformity of the final SIN film thickness measurement; while wet etching, although rarely used in back-end ALCU metal interconnects, has more advantages in terms of etching characteristics compared to dry etching, including greater selectivity, less damage to the substrate, and easier particle removal. Therefore, the technical solution of this invention was determined. The technical solution of this invention will be further described below with reference to the accompanying drawings.

[0030] Figure 1 The flowchart shown is a rework method for the upper electrode plate of the MIM according to an embodiment of the present invention.

[0031] like Figure 1 As shown, it includes the following steps:

[0032] Step 1: Provide the MIM structure for which the upper electrode plate needs to be reworked. The upper electrode plate is a TiN layer, and a dielectric layer is formed below the upper electrode plate.

[0033] In this embodiment of the invention, the dielectric layer is a SiN layer.

[0034] Step 2: Remove the TIN layer using APM wet etching.

[0035] In this embodiment of the invention, the solution used for APM wet etching is a mixture of NH4OH, H2O2, and H2O, with a composition ratio of NH4OH:H2O2:H2O = 1:1:5. The wet etching temperature is 55°C, and the etching rate is greater than 30 Å. Compared to the commonly used dry etching method in the later stages, it has a higher selectivity, causes less damage to the substrate, and is easier to remove particles, but it will roughen the underlying SiN dielectric layer.

[0036] Step 3: First, perform dry etching on the dielectric layer, and then perform two wet cleaning processes.

[0037] Dry etching followed by two wet cleaning processes is a mature process used in the etching of certain MIM SIN products. The dry etching process uses CH2F2 / Ar / O2 as the etching gas. Specifically, in this embodiment of the invention, the gas flow rate of CH2F2 is 5–100 sccm, the gas flow rate of Ar is 10–500 sccm, the gas flow rate of O2 is 5–100 sccm, the dry etching temperature is 20–100°C, and the RF power is 100–1000 W. The wet cleaning process uses ACT940 solution and lasts for 10–20 minutes.

[0038] Step 4: Perform dry etching on the dielectric layer again, followed by two wet cleaning processes.

[0039] When etching a thick SiN layer in a single step, a large amount of polymer is generated, making cleaning difficult. Therefore, in this embodiment of the invention, the same process steps are performed twice: the dielectric layer is first dry-etched, and then wet-cleaned twice.

[0040] Step 5: Perform film thickness and defect detection.

[0041] In this embodiment of the invention, the SIN dielectric layer is subjected to post-film inspection to confirm whether it has been completely removed; the surface of the MIM structure after the removal of the upper electrode TIN and the intermediate dielectric layer SIN is subjected to defect inspection to confirm whether there are pits and polymers on the surface.

[0042] Step 6: In response to the passing of film thickness and defect detection, the dielectric layer and TiN layer are regrowthed.

[0043] In this embodiment of the invention, passing the film thickness test means the film thickness is zero, passing the defect test means there are no pits or polymers, and the defect detection MAP is good. When both the film thickness test and the defect test are passed, the dielectric layer and the upper electrode TiN layer located in the wet process of the dielectric layer are reformed.

[0044] Step 7: Proceed with the subsequent process flow and conduct WAT testing upon completion.

[0045] WAT testing includes various WAT parameter tests. If the parameters of the rework wafer are the same as the baseline and the parameters are OK, then the rework is successful.

[0046] In this embodiment of the invention, the step between step two and step three includes measuring the thickness of the dielectric layer. The etching amount can be calculated by measuring the thickness of the dielectric layer.

[0047] Specifically, such as Figure 2 As shown, the rework method for the upper electrode plate of the MIM according to an embodiment of the present invention includes the following steps:

[0048] Step S11: Provide the MIM structure for the upper electrode plate that needs to be reworked.

[0049] Step S12: Remove the TIN layer using APM wet etching.

[0050] Step S13: Test the thickness of the dielectric layer and calculate the etching amount.

[0051] Step S14: First, perform dry etching on the dielectric layer, and then perform two wet cleaning processes.

[0052] Step S15: Perform dry etching on the dielectric layer again, followed by two wet cleaning processes.

[0053] Step S16: Perform film thickness detection. Confirm whether the dielectric layer has been removed.

[0054] Step S17: In response to the film thickness being zero, proceed to step S18; otherwise, return to step S15.

[0055] Step S18: Perform defect inspection. Confirm the appearance of the surface after etching.

[0056] Step S19: If the defect detection result is satisfactory and the MAP is good, proceed to step S20; otherwise, if the rework fails, end the rework process.

[0057] Step S20: Regenerate the dielectric layer and TiN layer.

[0058] Step S21: Proceed with the subsequent process flow.

[0059] Step S22: Perform WAT testing.

[0060] In this embodiment of the invention, if the WAT test result is passed, the rework is successful and the process proceeds to the next step; otherwise, the rework fails and the process ends.

[0061] In this embodiment of the invention, when the TIN film on the upper electrode of a MIM (Metal Injection Molding) is abnormal, the TIN and the underlying dielectric SIN are removed and reworked. First, the upper electrode is subjected to APM wet etching. Then, the dielectric layer undergoes one dry etching and two wet etching processes. This is repeated once more. After both film thickness and defect detection are passed, the dielectric layer and upper electrode are regrown for subsequent process flows. Finally, a WAT ​​(Waste Air Testing) test is performed. If the WAT test result is passed, the rework is complete, and the process proceeds to the next step. This method effectively reworks the upper electrode of the MIM, solves the problem of upper electrode abnormalities, reduces losses, and achieves a high rework success rate.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for reworking the upper electrode plate of a MIM (Metal Injection Molding) system, characterized in that, Includes the following steps: Step 1: Provide the MIM structure for which the upper electrode plate needs to be reworked. The upper electrode plate is a TiN layer, and a dielectric layer is formed below the upper electrode plate. Step 2: Remove the TIN layer using APM wet etching; Step 3: First, perform dry etching on the dielectric layer, and then perform two wet cleaning processes; Step 4: Perform dry etching on the dielectric layer again, followed by two wet cleaning processes; Step 5: Perform film thickness and defect detection; Step 6: In response to the passing of the film thickness detection and the defect detection, the dielectric layer and the TiN layer are regrown and formed; the passing of the film thickness detection means that the thickness of the dielectric layer is zero, and the passing of the defect detection means that there are no pits or polymers. Step 7: Proceed with the subsequent process flow and conduct WAT testing upon completion.

2. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The dielectric layer mentioned in step one is a SiN layer.

3. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The solution used for the APM wet etching is a mixture of NH4OH, H2O2 and H2O, the temperature is 55℃, and the etching rate is greater than 30A.

4. The rework method for the upper electrode plate of the MIM according to claim 3, characterized in that, The composition ratio of the solution is NH4OH:H2O2:H2O = 1:1:

5.

5. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The process between step two and step three includes measuring the film thickness of the dielectric layer.

6. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The dry etching conditions described in steps three and four are as follows: CH2F2 / Ar / O2 is used as the etching gas, wherein the gas flow rate of CH2F2 is 5-100 sccm, the gas flow rate of Ar is 10-500 sccm, the gas flow rate of O2 is 5-100 sccm, the temperature is 20-100℃, and the RF power is 100-1000W.

7. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The wet cleaning process described in steps three and four uses ACT940 solution.

8. The rework method for the upper electrode plate of the MIM according to claim 1, characterized in that, The method also includes: in response to the WAT test passing, rework is successful.

Images