Reworking method of top metal layer

Abstract

The application discloses a top metal layer rework method, which comprises the following steps: at least twice ashing treatment and twice solution cleaning treatment are performed on the polymer exposed on the surface of the top metal layer of a passivation layer, so as to remove part of the polymer; a photoresist layer is formed, and the photoresist layer covers the surface of the passivation layer; ion bombardment treatment is performed on the photoresist layer and the top metal layer exposed on the passivation layer, so as to remove the photoresist layer and the residual polymer; and ashing and solution cleaning treatment are performed, so as to remove the residual photoresist layer and the residual polymer on the surface of the top metal layer. After the polymer on the surface of the top metal layer is subjected to ashing and cleaning treatment, the photoresist layer is deposited again and the photoresist layer is subjected to ion bombardment, so as to remove the photoresist layer and the polymer. The polymer on the surface of the top metal layer can be completely removed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for reworking the top metal layer. Background Technology

[0002] With the development of circuit manufacturing technology and the increase in component integration, multiple chips can now be produced simultaneously on a single wafer. After these chips are fabricated, the individual chips on the wafer are typically diced from the others. To facilitate the dicing process, a certain amount of space is usually reserved between each chip as a dicing track to cut the wafer into multiple chips.

[0003] For existing cutting methods, please refer to [reference needed]. Figure 1 First, a wafer to be diced is provided. Multiple chips are formed on the wafer, including various device structures and a top metal layer 110. Therefore, the dicing path is located next to the chip, or more specifically, next to the top metal layer 110. Simultaneously, a passivation layer 120 is formed, covering the surface and sidewalls of the top metal layer 110 and the surface of the dicing path, protecting them from oxidation. Therefore, during dicing, the passivation layer 120 on the dicing path is removed first. Specifically, a photoresist layer 130 is formed on the surface of the passivation layer 120 and the sidewalls of the top metal layer 110. Next, please refer to... Figure 2 The passivation layer 120 not covered by the photoresist layer 130 is also the passivation layer 120 on the surface of the etched path. Next, please refer to... Figure 3 The photoresist layer 120 was removed using an ash method.

[0004] However, in the prior art, when the thickness of the top metal layer 110 is relatively thick, the thickness of its passivation layer 120 and photoresist layer 130 will also be relatively large. At this time, more polymer will be generated. If the polymer falls into the top metal layer 110, it may corrode the top metal layer if it is not removed in time, affecting the quality of the chip. Summary of the Invention

[0005] The purpose of this invention is to provide a method for reworking the top metal layer, which can clean the polymer on the surface of the top metal layer.

[0006] To achieve the above objectives, the present invention provides a method for reworking a top metal layer, wherein a portion of the top metal layer is covered by a passivation layer, comprising:

[0007] The polymer on the surface of the top metal layer exposed by the passivation layer is subjected to at least two ashing treatments and two solution cleaning treatments to remove some of the polymer;

[0008] A photoresist layer is formed, which covers the surface of the passivation layer;

[0009] The exposed top metal layer of the photoresist layer and the passivation layer is subjected to ion bombardment treatment to remove the photoresist layer and the remaining polymer;

[0010] Ashing and solution cleaning are performed to remove residual photoresist layer and residual polymer on the surface of the top metal layer.

[0011] Optionally, in the rework method of the top metal layer, the photoresist layer is bombarded with ions using Ar gas.

[0012] Optionally, in the rework method of the top metal layer, the power of the ion bombardment treatment is 790W to 810W.

[0013] Optionally, in the rework method of the top metal layer, the time for ion bombardment treatment of the exposed top metal layer of the photoresist layer and the passivation layer is 10s to 20s.

[0014] Optionally, in the rework method of the top metal layer, the material of the top metal layer includes aluminum.

[0015] Optionally, in the rework method of the top metal layer, an HF solution is used for solution cleaning.

[0016] Optionally, in the rework method of the top metal layer, performing at least two ashing treatments and two solution cleaning treatments on the polymer surface of the top metal layer includes performing a solution cleaning treatment after each ashing treatment.

[0017] Optionally, in the rework method of the top metal layer, the polymer on the surface of the top metal layer exposed by the passivation layer is subjected to two ashing treatments and two solution cleaning treatments.

[0018] Optionally, in the rework method of the top metal layer, a photoresist layer is formed on the surface of the top metal layer exposed by the passivation layer by deposition.

[0019] The rework method for the top metal layer provided by this invention includes: performing at least two ashing treatments and two solution cleaning treatments on the polymer exposed on the surface of the top metal layer of the passivation layer to remove some of the polymer; forming a photoresist layer covering the surface of the passivation layer; subjecting the exposed top metal layer of the photoresist layer and passivation layer to ion bombardment treatment to remove the photoresist layer and remaining polymer; and performing ashing and solution cleaning treatments to remove the residual photoresist layer and residual polymer on the surface of the top metal layer. This invention, after ashing and cleaning the polymer on the surface of the top metal layer, deposits a photoresist layer and then performs ion bombardment on the photoresist layer to remove the photoresist layer and polymer. This effectively removes the polymer from the surface of the top metal layer. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the semiconductor structure after the formation of the photoresist layer using existing technology;

[0021] Figure 2 This is a schematic diagram of the semiconductor structure after removing the passivation layer on the dicing track using existing technology.

[0022] Figure 3 This is a schematic diagram of the semiconductor structure after removing the photoresist layer using existing technology;

[0023] Figure 4 This is a flowchart of the rework method for the top metal layer according to an embodiment of the present invention;

[0024] In the diagram: 110 - top metal layer, 120 - passivation layer, 130 - photoresist layer. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0026] In the following text, the terms “first,” “second,” etc., are used to distinguish between similar elements and are not necessarily used to describe a specific order or chronological sequence. It should be understood that these terms, as used herein, may be replaced where appropriate. Similarly, if the methods described herein comprise a series of steps, and the order of these steps presented herein is not necessarily the only possible order in which they can be performed, and some described steps may be omitted and / or other steps not described herein may be added to the method.

[0027] Furthermore, it should be understood that when a layer (or film), region, pattern, or structure is referred to as being "on" a substrate, layer (or film), region, and / or pattern, it can be located directly on another layer or substrate, and / or intercalation layers may also be present. Additionally, it should be understood that when a layer is referred to as being "under" another layer, it can be located directly under that layer, and / or one or more intercalation layers may also be present. Furthermore, references to "on" and "under" the layers may be made based on the accompanying drawings.

[0028] With the development of circuit manufacturing technology and the increase in component integration, multiple chips can now be produced simultaneously on a single wafer. After these chips are fabricated, the individual chips on the wafer are typically diced from the others. To facilitate the dicing process, a certain amount of space is usually reserved between each chip as a dicing track to cut the wafer into multiple chips.

[0029] For existing cutting methods, please refer to [reference needed]. Figure 1 First, a wafer to be diced is provided. Multiple chips are formed on the wafer, including various device structures and a top metal layer 110. Therefore, the dicing path is located next to the chip, or more specifically, next to the top metal layer 110. Simultaneously, a passivation layer 120 is formed, covering the surface and sidewalls of the top metal layer 110 and the surface of the dicing path, protecting them from oxidation. Therefore, during dicing, the passivation layer 120 on the dicing path is removed first. Specifically, a photoresist layer 130 is formed on the surface of the passivation layer 120 and the sidewalls of the top metal layer 110. Next, please refer to... Figure 2 The passivation layer 120 not covered by the photoresist layer 130 is also the passivation layer 120 on the surface of the etched path. Next, please refer to... Figure 3 The photoresist layer 120 was removed using an ash method.

[0030] However, in the prior art, when the thickness of the top metal layer 110 is relatively thick, the thickness of its passivation layer 120 and photoresist layer 130 will also be relatively large. At this time, more polymer will be generated. If the polymer falls into the top metal layer 110, it may corrode the top metal layer if it is not removed in time, affecting the quality of the chip.

[0031] Therefore, please refer to Figure 3 This invention provides a method for reworking a top metal layer, wherein a portion of the top metal layer is covered by a passivation layer, comprising:

[0032] S11: The polymer on the surface of the top metal layer exposed by the passivation layer shall be subjected to at least two ashing treatments and two solution cleaning treatments to remove some of the polymer;

[0033] S12: Form a photoresist layer, which covers the surface of the passivation layer;

[0034] S13: Ion bombardment treatment is performed on the exposed top metal layer of the photoresist layer and passivation layer to remove the photoresist layer and residual polymer;

[0035] S14: Perform ashing and solution cleaning to remove residual polymers from the surface of the residual photoresist layer and the top metal layer.

[0036] In this embodiment of the invention, Ar gas is used to bombard the photoresist layer with ions. The power of the ion bombardment is 790W to 810W, for example, 800W; in other embodiments of the invention, it can also be 795W or 805W. The ion bombardment time for the top metal layer exposed by the photoresist layer and passivation layer is 10s to 20s, for example, 15s; in other embodiments of the invention, it can also be 11s or 19s. During ion bombardment, the chip can be placed in an ion bombardment device, and the ion bombardment device is set to a power of 790W to 810W, for example, 800W. The time is set to 10s to 20s, for example, 15s, thereby bombarding the photoresist layer with ions.

[0037] The top metal layer in this embodiment of the invention is made of aluminum. If the polymer is not completely removed, it will corrode the aluminum, causing damage to the top metal layer and affecting the chip quality. If the damage to the top metal layer is not detected in time, sending substandard chips to the next unit could result in significant losses. Therefore, it is necessary to detect defects in the top metal layer promptly and to process defective top metal layers. Analysis of the top metal layers of some chips revealed that some polymer adhered to the surface of the top metal layer. Further analysis showed that the polymer was generated during the dicing process, so the top metal layer of the chip needs to be reworked. Therefore, the top metal layer in step S11 of this embodiment of the invention is a top metal layer with polymer found after dicing.

[0038] Preferably, in step S12, a photoresist layer can be formed on the surface of the passivation layer by deposition, exposing the top metal layer. The deposition method can be chemical vapor deposition. Further, after step S13 involves ion bombardment of the photoresist layer and the exposed top metal layer of the passivation layer to remove the photoresist layer and remaining polymer, the process further includes solution cleaning of the top metal layer to remove residual polymer. Specifically, in this embodiment of the invention, after ion bombarding the photoresist layer with Ar gas for 15 seconds at a power of 800W, solution cleaning of the top metal layer is then performed.

[0039] In the several cleaning processes described in this invention embodiment, HF solution can be used for solution cleaning.

[0040] Preferably, in step S11, performing at least two ashing treatments and two solution cleaning treatments on the polymer surface of the top metal layer includes performing a solution cleaning treatment after each ashing treatment. For example, if the two ashing treatments are a first ashing treatment and a second ashing treatment, and the two solution cleaning treatments are a first solution cleaning treatment and a second solution cleaning treatment, then preferably, the two ashing treatments and two solution cleaning treatments are performed as follows: first ashing treatment, then the first solution cleaning treatment. Next, the second ashing treatment is performed, followed by the second solution cleaning treatment. Similarly, if there are three ashing treatments and three solution cleaning treatments, namely a first ashing treatment, a second ashing treatment, and a third ashing treatment, and the three solution cleaning treatments are a first solution cleaning treatment, a second solution cleaning treatment, and a third solution cleaning treatment, then preferably, the three ashing treatments and three solution cleaning treatments are performed as follows: first ashing treatment, then the first solution cleaning treatment. Next, the second ashing treatment is performed, then the second solution cleaning treatment. Finally, the third ashing treatment is performed, followed by the third solution cleaning treatment. Through multiple experiments, this invention has found that performing two ashing treatments and two solution cleaning treatments on the surface of the top metal layer can remove the polymer to the greatest extent. Therefore, this invention employs two ashing treatments: a first ashing treatment and a second ashing treatment. That is, the first ashing treatment is performed first, followed by a first solution cleaning treatment. Then, a second ashing treatment is performed, followed by a second solution cleaning treatment. Alternatively, in other embodiments of this invention, three ashing treatments and three solution cleaning treatments can be used: the first ashing treatment is performed first, followed by a first solution cleaning treatment. Then, a second ashing treatment is performed, followed by a second solution cleaning treatment. Finally, a third ashing treatment is performed, followed by a third solution cleaning treatment.

[0041] In summary, the rework method for the top metal layer provided in this embodiment of the invention includes: performing at least two ashing treatments and two solution cleaning treatments on the polymer exposed on the surface of the top metal layer of the passivation layer to remove some of the polymer; forming a photoresist layer covering the surface of the passivation layer; subjecting the exposed top metal layer of the photoresist layer and passivation layer to ion bombardment treatment to remove the photoresist layer and remaining polymer; and performing ashing and solution cleaning treatments to remove the residual photoresist layer and residual polymer on the surface of the top metal layer. This invention, after ashing and cleaning the polymer on the surface of the top metal layer, deposits a photoresist layer and then performs ion bombardment on the photoresist layer to remove the photoresist layer and polymer. This effectively removes the polymer from the surface of the top metal layer.

[0042] 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 reworking a top metal layer, wherein a portion of the top metal layer is covered by a passivation layer, characterized in that, include: The polymer on the surface of the top metal layer exposed by the passivation layer is subjected to at least two ashing treatments and two solution cleaning treatments to remove some of the polymer, which is generated during the cutting process of the cutting channel; A photoresist layer is formed, which covers the surface of the passivation layer; The exposed top metal layer of the photoresist layer and the passivation layer is subjected to ion bombardment treatment to remove the photoresist layer and the remaining polymer; Ashing and solution cleaning are performed to remove residual photoresist layer and residual polymer on the surface of the top metal layer.

2. The rework method for the top metal layer as described in claim 1, characterized in that, The photoresist layer was bombarded with ions using Ar gas.

3. The rework method for the top metal layer as described in claim 1, characterized in that, The power of the ion bombardment treatment is 790W~810W.

4. The rework method for the top metal layer as described in claim 1, characterized in that, The ion bombardment treatment time for the exposed top metal layer of the photoresist layer and the passivation layer is 10s~20s.

5. The rework method for the top metal layer as described in claim 1, characterized in that, The material of the top metal layer includes aluminum.

6. The rework method for the top metal layer as described in claim 1, characterized in that, Solution cleaning was performed using HF solution.

7. The rework method for the top metal layer as described in claim 1, characterized in that, The polymer on the surface of the top metal layer exposed by the passivation layer is subjected to at least two ashing treatments and two solution cleaning treatments, including a solution cleaning treatment after each ashing treatment.

8. The rework method for the top metal layer as described in claim 1, characterized in that, The polymer on the surface of the top metal layer exposed by the passivation layer is subjected to two ashing treatments and two solution cleaning treatments.

9. The rework method for the top metal layer as described in claim 1, characterized in that, A photoresist layer is formed on the surface of the top metal layer by deposition.

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