Reworking method of MIM upper electrode plate

Abstract

The invention provides a reworking method of an MIM upper pole plate, which comprises the following steps: providing an MIM structure of the upper pole plate to be reworked, the upper pole plate is a TiN layer, and a dielectric layer is formed below the upper pole plate; the TIN layer is removed through APM wet etching; carrying out dry etching on the dielectric layer, and then carrying out wet cleaning treatment twice; carrying out dry etching on the dielectric layer again, and then carrying out wet cleaning treatment twice; performing film thickness detection and defect detection; in response to film thickness detection and defect detection, regrowing to form a dielectric layer and a TiN layer; and carrying out a subsequent process flow, and carrying out a WAT test after the subsequent process flow is completed. The method is used for reworking the wafer when the MIM upper electrode plate is abnormal, wet etching is carried out on the upper electrode plate, dry etching and wet etching are carried out on the dielectric layer for multiple times, after film thickness detection and defect detection pass, the dielectric layer and the upper electrode plate are formed through regrowth, the problem that the MIM upper electrode plate is abnormal is solved, the reworking success rate is increased, and the reworking efficiency is improved. And the device yield is improved.

Description

Technical Field

[0001] The invention relates to the growth of semiconductor materials and related processing technologies in the field of semiconductor integrated circuit manufacturing, and in particular to a reworking method for a MIM upper plate. Background Art

[0002] Capacitors are one of the commonly used passive devices. As an important component of integrated circuits, they are widely used in various chips. The capacitor structures in integrated circuit chips include MIM (metal insulator metal), PIP (poly insulator poly) and MOM (metal oxide metal).

[0003] MIM capacitors include a lower plate, an upper plate, and a dielectric layer between the upper plate and the lower plate, and can be manufactured during the BEOL (Back End of Line) process. During the manufacture of the upper plate, due to the excessive consumption of the target material of the sputtering TIN, the quality of the growing film changes, making the Rs uniformity unstable, and causing the EPD (End Point Detection) to sound an alarm during MIM_ET. Summary of the invention

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

[0005] The present invention provides a reworking method for a MIM upper plate, comprising the following steps:

[0006] Step 1, providing a MIM structure of an upper plate to be reworked, wherein the upper plate is a TiN layer, and a dielectric layer is formed below the upper plate;

[0007] Step 2: removing the TIN layer by APM wet etching;

[0008] Step 3, first dry-etching the dielectric layer, and then performing two wet cleaning processes;

[0009] Step 4, dry-etching the dielectric layer again, and then performing two wet cleaning processes;

[0010] Step 5: Conduct defect detection;

[0011] Step 6: in response to the defect detection being passed, regrowing the dielectric layer and the TiN layer;

[0012] Step 7: Carry out the subsequent process flow and perform WAT test after completion.

[0013] Preferably, the dielectric layer in step 1 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, after step 2 and before step 3, the method includes: measuring the film thickness of the dielectric layer.

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

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

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

[0020] Preferably, the method further comprises: in response to the WAT test being passed, the rework is successful.

[0021] The present invention reworks the MIM structure of the upper electrode plate that needs to be reworked, firstly wet-etches the upper electrode plate, then performs one dry process and two wet processes on the dielectric layer, then performs one dry process and two wet processes on the dielectric layer again, then re-grows the dielectric layer and the upper electrode plate after both the film thickness detection and the defect detection are passed, performs subsequent process flow, and finally performs WAT test, thereby realizing the rework of the MIM upper electrode plate, solving the problem of abnormality of the MIM upper electrode plate, and reducing the loss. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1 Shown is a flow chart of a reworking method for a MIM upper plate according to an embodiment of the present invention;

[0024] Figure 2 Shown is a flowchart of a reworking method for a MIM top plate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0026] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0027] Unless the context clearly requires otherwise, the words "include", "comprising" and similar words throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

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

[0029] For the abnormal situation of the MIM upper plate, the solution is to remove the upper plate TIN and the intermediate dielectric layer SIN, and then re-grow the intermediate dielectric layer and the upper plate. Specifically, there are many combinations of methods to remove the upper plate TIN and the intermediate dielectric layer SIN, especially for the etching of the upper plate TIN, which can be done by CMP, dry etching, wet etching, etc. After a variety of combined experiments, it was found that the mechanical flattening method of CMP would cause damage, which eventually led to pits on the surface after removal; after the dry etching was completed, the final SIN film thickness measurement uniformity was poor; and wet etching, although wet etching is almost not used in the later ALCU metal interconnection line, but in terms of etching characteristics, isotropic wet etching has more advantages than dry etching, such as large selectivity, less damage to the substrate, and easier removal of particles. Thus, the technical solution of the present invention is determined. The technical solution of the present invention is further explained below in conjunction with the accompanying drawings.

[0030] Figure 1 Shown is a flow chart of a reworking method for a MIM top plate according to an embodiment of the present invention.

[0031] like Figure 1 As shown, the following steps are included:

[0032] Step 1: Provide a MIM structure of an upper plate to be reworked, wherein the upper plate is a TiN layer, and a dielectric layer is formed below the upper plate.

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

[0034] Step 2: Use APM wet etching to remove the TIN layer.

[0035] The solution used for APM wet etching in the embodiment of the present invention is a mixture of NH4OH, H2O2 and H2O, and the composition ratio of the solution is NH4OH:H2O2:H2O=1:1:5. The temperature of wet etching is 55°C, and the etching rate is greater than 30A. Compared with the commonly used dry etching in the back stage, the selectivity is large, the damage to the substrate is small, and the particles are easier to remove, but the underlying SIN medium will be etched rough.

[0036] Step 3: dry-etch the dielectric layer first, and then perform two wet cleaning processes.

[0037] Dry etching the dielectric layer first and then performing two wet cleaning processes is a mature application process of some MIM SIN etching products. The dry etching uses CH2F2 / Ar / O2 as the etching gas. Specifically, in an embodiment of the present invention, the gas flow rate of CH2F2 is 5 to 100 sccm, the gas flow rate of Ar is 10 to 500 sccm, the gas flow rate of O2 is 5 to 100 sccm, the temperature of dry etching is 20 to 100°C, and the RF power is 100 to 1000W. The wet cleaning process uses ACT940 solution for 10 to 20 minutes.

[0038] Step 4: dry-etch the dielectric layer again, and then perform two wet cleaning processes.

[0039] When etching a thicker SIN in one step, a large amount of polymer will be generated, which makes cleaning difficult. Therefore, in the embodiment of the present invention, the same process steps are performed twice, and the dielectric layer is first dry-etched again, and then wet-cleaned twice.

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

[0041] In an embodiment of the present invention, the dielectric layer SIN is subjected to post-film inspection to confirm whether it is completely removed; and the surface of the MIM structure after the top plate TIN and the middle dielectric layer SIN are removed is subjected to defect inspection to confirm whether there are pits and polymers on the surface.

[0042] Step 6: In response to the film thickness detection and defect detection being passed, the dielectric layer and the TiN layer are regrown.

[0043] In the embodiment of the present invention, passing the film thickness test means that the film thickness is zero, passing the defect test means that there are no pits and polymers, and the defect test MAP is good. In the case of passing both the film thickness test and the defect test, the dielectric layer and the upper plate TiN layer located on the dielectric layer by wet process are re-formed.

[0044] Step 7: Carry out the subsequent process flow and perform WAT test after completion.

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

[0046] In the embodiment of the present invention, after step 2 and before step 3, the step includes: measuring the thickness of the dielectric layer. The etching amount can be calculated by measuring the thickness of the dielectric layer.

[0047] Specifically, Figure 2 As shown, the reworking method of the MIM upper plate of the embodiment of the present invention comprises the following steps:

[0048] Step S11, providing a MIM structure of the upper plate to be reworked.

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

[0050] Step S13, testing the thickness of the dielectric layer and calculating the etching amount.

[0051] Step S14, first dry-etching the dielectric layer, and then performing two wet cleaning processes.

[0052] Step S15, dry-etching the dielectric layer again, and then performing two wet cleaning processes.

[0053] Step S16: Perform film thickness detection to 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 detection to confirm the appearance of the surface after etching.

[0056] Step S19: In response to the defect detection result passing and the MAP being good, proceed to step S20; otherwise, the rework fails and the rework ends.

[0057] Step S20, regrow to form a dielectric layer and a TiN layer.

[0058] Step S21, carry out subsequent process flow.

[0059] Step S22: perform WAT test.

[0060] In the embodiment of the present invention, in response to the WAT test result being passed, the rework is successful and the next process flow is entered; otherwise, the rework fails and the rework is ended.

[0061] In the embodiment of the present invention, when the film quality of the TIN film of the MIM upper plate is abnormal, the TIN and the lower dielectric SIN are removed and reworked. First, the upper plate is subjected to APM wet etching, and then the dielectric layer is subjected to one dry process and two wet processes, and then the dielectric layer is subjected to one dry process and two wet processes again. Then, after the film thickness detection and defect detection are passed, the dielectric layer and the upper plate are regrown to form a subsequent process flow, and finally a WAT ​​test is performed. If the WAT test result passes, the rework is terminated and the next process flow is entered. In this way, the rework of the MIM upper plate is realized, the problem of the abnormal MIM upper plate is solved, the loss is reduced, and the rework success rate is high.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A reworking method for a MIM upper plate, characterized in that: The following steps are involved: Step 1, providing a MIM structure of an upper plate to be reworked, wherein the upper plate is a TiN layer, and a dielectric layer is formed below the upper plate; Step 2: removing the TIN layer by APM wet etching; Step 3, first dry-etching the dielectric layer, and then performing two wet cleaning processes; Step 4, dry-etching the dielectric layer again, and then performing two wet cleaning processes; Step 5: Conduct film thickness detection and defect detection; Step 6: in response to the film thickness detection and the defect detection being passed, regrowing the dielectric layer and the TiN layer; Step 7: Carry out the subsequent process flow and perform WAT test after completion.

2. The reworking method of the MIM upper plate according to claim 1, characterized in that: The dielectric layer in step 1 is a SiN layer.

3. The reworking method of the MIM upper plate 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°C, and the etching rate is greater than 30A.

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

5.

5. The reworking method of the MIM upper plate according to claim 1, characterized in that: After step 2 and before step 3, the method includes: measuring the film thickness of the dielectric layer.

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

7. The reworking method of the MIM upper plate according to claim 1, characterized in that: The wet cleaning process in step 3 and step 4 uses ACT940 solution.

8. The reworking method of the MIM upper plate according to claim 1, characterized in that: In step six, the film thickness test passing means that the film thickness is zero, and the defect test passing means that there are no pits and polymers.

9. The reworking method of the MIM upper plate according to claim 1, characterized in that: The method further includes: in response to the WAT test passing, the rework is successful.

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