Reworking method of top metal layer

Abstract

The invention relates to a reworking method of a top metal layer, which comprises the following steps of: at least carrying out ashing treatment twice and solution cleaning treatment twice on a polymer on the surface of the top metal layer exposed out of a passivation layer so as to remove part of the polymer; forming a photoresist layer, wherein the photoresist layer covers the surface of the passivation layer; carrying out ion bombardment treatment on the photoresist layer and the top metal layer exposed out of the passivation layer to remove the photoresist layer and the residual polymer; and performing ashing and solution cleaning treatment to remove residual polymers on the surfaces of the residual photoresist layer and the top metal layer. According to the invention, after ashing and cleaning treatment is carried out on the polymer on the surface of the top metal layer, the photoresist layer is deposited and ion bombardment is carried out on the photoresist layer, so that the photoresist layer and the polymer are removed. The polymer on the surface of the top metal layer can be cleaned.

Description

Technical Field

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

[0002] With the development of circuit process technology and the improvement of component integration, multiple chips can be produced on the same wafer at the same time. Usually after these chips are made, each independent chip on the wafer is cut away from other chips. In order to facilitate the cutting process, a certain space is usually reserved between each chip as a cutting path to cut the wafer into multiple chips.

[0003] In the prior art, the cutting method is shown in Figure 1 First, provide a wafer to be cut, on which multiple chips are formed. The chips include various device structures and a top metal layer 110 located at the top. Therefore, next to the chip or next to the top metal layer 110 is the cutting path. At the same time, a passivation layer 120 is formed. The passivation layer 120 covers the surface and side walls of the top metal layer 110 and the surface of the cutting path to protect them from oxidation. Therefore, when cutting, the passivation layer 120 on the cutting path will be cut off first. Specifically, a photoresist layer 130 is formed on the surface of the passivation layer 120 on the top metal layer 110 and the side walls of the top metal layer 110. Please refer to Figure 2 , the passivation layer 120 not covered by the photoresist layer 130 is etched, that is, the passivation layer 120 on the surface of the cutting path. Figure 3 , the photoresist layer 120 is removed using an ash method.

[0004] However, in the prior art, when the thickness of part of the top metal layer 110 is relatively thick, the thickness of the passivation layer 120 and the photoresist layer 130 will also be relatively thick. At this time, more polymers will be produced and fall into the top metal layer 110. If the polymers are not removed in time, the polymers may corrode the top metal layer and affect the quality of the chip. Summary of the invention

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

[0006] In order to achieve the above object, the present invention provides a reworking method of a top metal layer, wherein part of the top metal layer is covered by a passivation layer, comprising:

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

[0008] forming a photoresist layer, wherein the photoresist layer covers the surface of the passivation layer;

[0009] Performing ion bombardment treatment on the photoresist layer and the top metal layer exposed by the passivation layer to remove the photoresist layer and the remaining polymer;

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

[0011] Optionally, in the reworking method of the top metal layer, Ar gas is used to perform ion bombardment on the photoresist layer.

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

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

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

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

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

[0017] Optionally, in the reworking 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 reworking 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 a deposition method.

[0019] The reworking method of the top metal layer provided by the present invention includes: performing at least two ashing treatments and two solution cleaning treatments on the polymer on the surface of the top metal layer exposed by the passivation layer to remove part of the polymer; forming a photoresist layer, the photoresist layer covering the surface of the passivation layer; performing ion bombardment treatment on the photoresist layer and the top metal layer exposed by the passivation layer to remove the photoresist layer and the remaining polymer; performing ashing and solution cleaning treatments to remove the residual photoresist layer and the residual polymer on the surface of the top metal layer. After the present invention performs ashing and cleaning treatments on the polymer on the surface of the top metal layer, a photoresist layer is deposited and ion bombardment is performed on the photoresist layer to remove the photoresist layer and the polymer. The polymer on the surface of the top metal layer can be cleaned. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a semiconductor structure after a photoresist layer is formed in the prior art;

[0021] Figure 2 It is a schematic diagram of a semiconductor structure after removing the passivation layer on the cutting path in the prior art;

[0022] Figure 3 It is a schematic diagram of a semiconductor structure after removing the photoresist layer in the prior art;

[0023] Figure 4 is a flow chart of a method for reworking a top metal layer according to an embodiment of the present invention;

[0024] In the figure: 110 - top metal layer, 120 - passivation layer, 130 - photoresist layer. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0026] Hereinafter, the terms "first", "second", etc. are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It is to be understood that these terms used in this manner are interchangeable where appropriate. Similarly, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some 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 directly on another layer or substrate, and / or there can be intervening layers. In addition, it should be understood that when a layer is referred to as being "under" another layer, it can be directly under another layer, and / or there can be one or more intervening layers. In addition, references to being "on" and "under" each layer can be made based on the accompanying drawings.

[0028] With the development of circuit process technology and the improvement of component integration, multiple chips can be produced on the same wafer at the same time. Usually after these chips are made, each independent chip on the wafer is cut away from other chips. In order to facilitate the cutting process, a certain space is usually reserved between each chip as a cutting path to cut the wafer into multiple chips.

[0029] In the prior art, the cutting method is shown in Figure 1 First, provide a wafer to be cut, on which multiple chips are formed. The chips include various device structures and a top metal layer 110 located at the top. Therefore, next to the chip or next to the top metal layer 110 is the cutting path. At the same time, a passivation layer 120 is formed. The passivation layer 120 covers the surface and side walls of the top metal layer 110 and the surface of the cutting path to protect them from oxidation. Therefore, when cutting, the passivation layer 120 on the cutting path will be cut off first. Specifically, a photoresist layer 130 is formed on the surface of the passivation layer 120 on the top metal layer 110 and the side walls of the top metal layer 110. Please refer to Figure 2 , the passivation layer 120 not covered by the photoresist layer 130 is etched, that is, the passivation layer 120 on the surface of the cutting path. Figure 3 , the photoresist layer 120 is removed using an ash method.

[0030] However, in the prior art, when the thickness of part of the top metal layer 110 is relatively thick, the thickness of the passivation layer 120 and the photoresist layer 130 will also be relatively thick. At this time, more polymers will be produced and fall into the top metal layer 110. If the polymers are not removed in time, the polymers may corrode the top metal layer and affect the quality of the chip.

[0031] Therefore, please refer to Figure 3 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:

[0032] S11: performing at least two ashing treatments and two solution cleaning treatments on the polymer on the surface of the top metal layer exposed by the passivation layer to remove part of the polymer;

[0033] S12: forming a photoresist layer, wherein the photoresist layer covers the surface of the passivation layer;

[0034] S13: performing ion bombardment treatment on the top metal layer exposed by the photoresist layer and the passivation layer to remove the photoresist layer and the remaining polymer;

[0035] S14: performing ashing and solution cleaning processes to remove the residual photoresist layer and the residual polymer on the surface of the top metal layer.

[0036] In an embodiment of the present invention, Ar gas is used to perform ion bombardment on the photoresist layer. The power of the ion bombardment treatment is 790W to 810W, for example, it can be 800W, and in other embodiments of the present invention, it can also be 795W or 805W. The time for ion bombardment treatment of the top metal layer exposed by the photoresist layer and the passivation layer is 10s to 20s, for example, it can be 15s, and in other embodiments of the present 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 can be set to a power of 790W to 810W, for example, it can be 800W. The time is set to 10s to 20s, for example, it can be 15s, so as to perform ion bombardment on the photoresist layer.

[0037] The material of the top metal layer of the embodiment of the present invention includes aluminum. If the polymer is not completely removed, the polymer will corrode the aluminum metal, so the top metal layer will be damaged, thereby affecting the quality of the chip. If the damage to the top metal layer is not discovered in time, the chips that do not meet the quality standards will be transferred to the next unit, which may cause very large losses. Therefore, it is necessary to promptly discover the defects of the top metal layer and deal with the defective top metal layer. After analyzing and processing the top metal layer of some chips, it was found that some polymers were attached to the surface of the top metal layer. After analysis, it was found that the polymers were generated during the cutting process of the cutting path, so the top metal layer of the chip needs to be reworked at this time. Therefore, the top metal layer in step S11 of the embodiment of the present invention is already the top metal layer where polymers were found after cutting.

[0038] Preferably, in the specific steps of step S12, a photoresist layer can be formed on the surface of the passivation layer by a deposition method, and the photoresist layer exposes the top metal layer, and the specific deposition method can be a chemical vapor deposition method. Further, in step S13, after the photoresist layer and the top metal layer exposed by the passivation layer are subjected to ion bombardment treatment to remove the photoresist layer and the remaining polymer, it also includes: the top metal layer is subjected to solution cleaning treatment to remove the residual polymer. Specifically, the embodiment of the present invention uses Ar gas to ion bombard the photoresist layer for 15s when the power is 800W. The top metal layer will continue to be subjected to solution cleaning treatment.

[0039] The several times of using solution for cleaning treatment in the embodiment of the present invention can all use HF solution for solution cleaning treatment.

[0040] Preferably, in step S11, the polymer on the surface of the top metal layer is subjected to at least two ashing treatments and two solution cleaning treatments, including: a solution cleaning treatment is performed after each ashing treatment. If the two ashing treatments are the first ashing treatment and the second ashing treatment, respectively, and the two solution cleaning treatments are the first solution cleaning treatment and the second solution cleaning treatment, respectively. Therefore, it is best to perform the first ashing treatment first and then the first solution cleaning treatment for these two ashing treatments and two solution cleaning treatments. Then, perform the second ashing treatment and then the second solution cleaning treatment. Similarly, if there are three ashing treatments and three solution cleaning treatments, they are the first ashing treatment, the second ashing treatment and the third ashing treatment, respectively, and the three solution cleaning treatments are the first solution cleaning treatment, the second solution cleaning treatment and the third solution cleaning treatment. Therefore, it is best to perform the first ashing treatment first and then the first solution cleaning treatment for these three ashing treatments and three solution cleaning treatments. Then, perform the second ashing treatment and then the second solution cleaning treatment. Finally, perform the third ashing treatment and then the third solution cleaning treatment. After many experiments, the embodiments of the present invention found that the polymer on the surface of the top metal layer can be removed to the greatest extent by subjecting it to two ashing treatments and two solution cleaning treatments. Therefore, the embodiments of the present invention use two ashing treatments, namely the first ashing treatment and the second ashing treatment, that is, the first ashing treatment is performed first, and then the first solution cleaning treatment is performed. Then, the second ashing treatment is performed, and then the second solution cleaning treatment is performed. Of course, in other embodiments of the present invention, three ashing treatments and three solution cleaning treatments may also be used, that is, the first ashing treatment is performed first, and then the first solution cleaning treatment is performed. Then, the second ashing treatment is performed, and then the second solution cleaning treatment is performed. Finally, the third ashing treatment is performed, and then the third solution cleaning treatment is performed.

[0041] In summary, the reworking method of the top metal layer provided in the embodiment of the present invention includes: performing at least two ashing treatments and two solution cleaning treatments on the polymer on the surface of the top metal layer exposed by the passivation layer to remove part of the polymer; forming a photoresist layer, the photoresist layer covering the surface of the passivation layer; performing ion bombardment treatment on the photoresist layer and the top metal layer exposed by the passivation layer to remove the photoresist layer and the remaining polymer; performing ashing and solution cleaning treatments to remove the residual photoresist layer and the residual polymer on the surface of the top metal layer. After the present invention performs ashing and cleaning treatments on the polymer on the surface of the top metal layer, a photoresist layer is deposited and ion bombardment is performed on the photoresist layer to remove the photoresist layer and the polymer. The polymer on the surface of the top metal layer can be cleaned.

[0042] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A method for reworking a top metal layer, part of which is covered by a passivation layer, characterized in that: include: Performing at least two ashing treatments and two solution cleaning treatments on the polymer on the surface of the top metal layer exposed by the passivation layer to remove part of the polymer; forming a photoresist layer, wherein the photoresist layer covers the surface of the passivation layer; Performing ion bombardment treatment on the photoresist layer and the top metal layer exposed by the passivation layer to remove the photoresist layer and the remaining polymer; Ashing and solution cleaning are performed to remove the residual photoresist layer and the residual polymer on the surface of the top metal layer.

2. The method for reworking the top metal layer according to claim 1, characterized in that: The photoresist layer is subjected to ion bombardment using Ar gas.

3. The method for reworking the top metal layer according to claim 1, characterized in that: The power of the ion bombardment treatment is 790W-810W.

4. The method for reworking the top metal layer according to claim 1, characterized in that: The time for performing ion bombardment treatment on the photoresist layer and the top metal layer exposed by the passivation layer is 10s to 20s.

5. The method for reworking the top metal layer according to claim 1, characterized in that: The material of the top metal layer includes aluminum.

6. The method for reworking the top metal layer according to claim 1, characterized in that: The solution cleaning treatment was performed using an HF solution.

7. The method for reworking the top metal layer according to 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: each ashing treatment is followed by a solution cleaning treatment.

8. The method for reworking the top metal layer according to 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 method for reworking the top metal layer according to claim 1, characterized in that: A photoresist layer is formed on the surface of the top metal layer by a deposition method.

Images