CN109887901B - Method for preventing metal fuse from being over-etched - Google Patents
Method for preventing metal fuse from being over-etched Download PDFInfo
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- CN109887901B CN109887901B CN201910144770.6A CN201910144770A CN109887901B CN 109887901 B CN109887901 B CN 109887901B CN 201910144770 A CN201910144770 A CN 201910144770A CN 109887901 B CN109887901 B CN 109887901B
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Abstract
The invention provides a method for preventing a metal fuse from being over-etched, which comprises the steps of providing a metal fuse, and depositing an interlayer film on the metal fuse; forming a top metal layer on the interlayer film, wherein the upper surface and the lower surface of the top metal layer are respectively provided with a titanium nitride layer; etching the top metal layer to form a welding pad and a protection pattern positioned above the metal fuse; after depositing a passivation layer, defining an etching window above the welding pad and the protection pattern; and etching according to the etching window to remove the titanium nitride on the upper surface of the bonding pad, and opening windows on the left and right of the metal fuse to release products generated when the metal fuse is blown while protecting the lower fuse by using the protection pattern as a mask. The invention realizes that the metal fuse wire is protected and windowed on the metal fuse wire, the metal fuse wire at the lower layer is protected while the cost is reduced, but the windows are opened at the left edge and the right edge of the metal fuse wire, so that the products generated when the metal fuse wire is blown can be released in time, and the short circuit can be prevented from being formed by gathering in situ.
Description
Technical Field
The invention relates to a semiconductor manufacturing process, in particular to a method for preventing a metal fuse from being over-etched.
Background
In a semiconductor manufacturing process, a passivation layer on a metal fuse is opened, and since a certain thickness of a silicon dioxide passivation layer on the metal fuse is required, the passivation layer is specially defined by a layer of photolithography and then is etched separately. As shown in fig. 1a, fig. 1a is a schematic diagram illustrating a metal fuse region defined by one photolithography in the prior art. The passivation layer and the interlayer film 02 are provided with a bonding pad 01 and a metal fuse 05, photoresist 03 is coated above the bonding pad 01 and the metal fuse 05 in a suspending mode, and an etching window 04 is opened above the metal fuse. FIG. 1b is a schematic diagram illustrating a one-step photolithography process for defining a pad region in the prior art. The photoresist continues to be over the structure shown in fig. 1a, and then an etch window 06 is opened over the pad by exposure and development.
The general process not only ensures that the titanium nitride on the bonding pad is etched cleanly without residue, but also ensures that the thickness of the silicon dioxide passivation layer on the metal fuse is about 500A-4000A. As shown in fig. 1c, fig. 1c is a schematic diagram illustrating a process of etching a pad region and a metal fuse simultaneously in the prior art. If the pad etching is directly used to omit a photolithography, the thickness of the silicon dioxide on the metal fuse cannot be guaranteed because the etching rate of the titanium nitride is slower than that of the silicon dioxide. As shown in fig. 2, fig. 2 is an enlarged view of a microscope showing a metal fuse being over-etched in the prior art: it can be seen that the metal fuse has been completely etched, and is seriously cut.
The method for solving the above problems can be achieved by adjusting the etching program (recipe), but the excessively increased etching rate of titanium nitride will deteriorate the equipment and generate particles.
Therefore, a new method is needed to solve the above problems.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a method for preventing a metal fuse from being over-etched, which is used to solve the problem in the prior art that the thickness of silicon dioxide above the metal fuse is not guaranteed due to the fact that the etching rate of titanium nitride is slower than that of the passivation layer and the silicon dioxide of the interlayer film.
To achieve the above and other related objects, the present invention provides a method for preventing a metal fuse from being over-etched, the method at least comprising the following steps: providing an interlayer film, wherein a metal fuse is arranged in the interlayer film; secondly, forming a top metal layer on the interlayer film, wherein the upper surface and the lower surface of the top metal layer are respectively provided with a titanium nitride layer; etching the top metal layer to form a welding pad and a protection pattern positioned above the metal fuse wire; depositing a passivation layer on the welding pad and the protection pattern, and photoetching and defining an etching window above the welding pad and the protection pattern; and fifthly, etching according to the etching window to remove the titanium nitride on the upper surface of the bonding pad, and opening windows on the left and right of the metal fuse to release products generated when the metal fuse is blown while protecting the lower fuse by using the protection pattern as a mask.
Preferably, in the first step, the interlayer film is made of silicon dioxide, and the upper and lower surfaces of the metal fuse respectively have titanium nitride layers.
Preferably, the material of the top metal layer in the second step is aluminum or aluminum copper alloy.
Preferably, the method for forming the pad and the protection pattern in step three includes: (1) suspending photoresist on the titanium nitride layer on the upper surface of the top metal layer; (2) then carrying out exposure and development; (3) forming an etching window of the welding pad pattern and an etching window of the protection pattern; (4) and etching the top metal layer according to the etching window, and taking the interlayer film as an etching stop layer.
Preferably, the critical dimension of the protection pattern is smaller than that of the metal fuse.
Preferably, the method for defining the etching window above the pad and above the protection pattern in the fourth step includes: (1) depositing a passivation layer on the upper surface of the bonding pad, the upper surface of the protection pattern and the upper surface of the interlayer film exposed outside; (2) suspending photoresist on the upper surface of the deposited passivation layer; (3) and exposing and developing the photoresist to form an etching window.
Preferably, the width of the windows opened at the left and right sides of the metal fuse in the step five is larger than that of the metal fuse.
Preferably, in the process of opening the windows left and right of the metal fuse in the fifth step, the left and right sides of the upper surface of the metal fuse are partially etched. As described above, the method for preventing the metal fuse from being over-etched according to the present invention has the following beneficial effects: in the IC process, the photoetching and etching of the original welding pad are utilized, and a specific protection pattern of the top metal layer is added, so that the metal fuse can be protected, windows can be opened on the metal fuse, the cost is reduced, and the application of customers is met. The protection pattern like a mask protects the underlying metal fuse, but opens windows at the left and right edges of the metal fuse for timely release of the products generated when the metal fuse is blown, so as to prevent the build-up from forming a short circuit in situ.
Drawings
FIG. 1a is a schematic diagram illustrating a one-step photolithography process for defining a metal fuse region in the prior art;
FIG. 1b is a schematic diagram illustrating a one-step photolithography process for defining a pad region in the prior art;
FIG. 1c is a schematic diagram illustrating a prior art process of etching a pad region and a metal fuse at the same time;
FIG. 2 is an enlarged cross-sectional view of an electron microscope showing a prior art over-etched metal fuse while simultaneously etching a pad region and the metal fuse;
FIG. 3 is a schematic diagram of a structure of forming a bonding pad and a protection pattern over the metal fuse according to the present invention;
FIG. 4 is a schematic diagram of a structure of forming an etching window above a bonding pad and above a protection pattern according to the present invention;
FIG. 5 is a schematic structural diagram of the present invention for removing titanium nitride on the bonding pad and windowing the left and right sides of the metal fuse;
FIG. 6 is a flowchart illustrating a method for preventing over-etching of a metal fuse according to the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1a to fig. 6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
Referring to fig. 6, fig. 6 is a flowchart illustrating a method for preventing over-etching of a metal fuse according to the present invention.
Providing an interlayer film, wherein a metal fuse is arranged in the interlayer film; the metal fuse is formed by the metal at the lower layer of the top layer fuse, and the interlayer film is deposited on the metal fuse to form a structure of the metal fuse in the interlayer film; as shown in fig. 3, fig. 3 is a schematic structural diagram illustrating a pad and a protection pattern over the metal fuse according to the present invention. As shown in fig. 3, a metal fuse 05 is provided in the interlayer film 02.
Further, the material of the interlayer film in the first step is silicon dioxide. The upper surface and the lower surface of the metal fuse are respectively provided with a titanium nitride layer. The metal in the laminated structure of the metal fuse is made of aluminum or aluminum-copper alloy. That is to say, the metal material in the laminated structure of the metal fuse is the material of the metal layer below the metal layer in the original process, and is compatible with the original process.
Step two, forming a top metal layer (top metal) on the upper surface of the interlayer film 02, that is, depositing a metal layer on the upper surface of the interlayer film to form the top metal layer. Correspondingly, when the layout is designed, a protection pattern covering the metal fuse is drawn right above the metal fuse.
The upper surface and the lower surface of the top metal layer are respectively provided with a titanium nitride layer, namely the top metal layer is a laminated structure consisting of titanium nitride-metal-titanium nitride; preferably, the material of the top metal layer in the second step is aluminum or a top aluminum material that is aluminum copper and compatible with the original process. The titanium nitride on the lower surface of the top metal layer is in direct contact with the upper surface of the interlayer film. Namely, the upper surface of the interlayer film is sequentially provided with titanium nitride, metal aluminum and titanium nitride from bottom to top.
And forming a bonding pad structure on the part of the top metal layer far away from the upper part of the metal fuse. The protective pattern and the pad structure are formed by photolithography and etching.
Etching the top metal layer to form a welding pad and a protection pattern positioned above the metal fuse wire; as shown in fig. 3, in this embodiment, a top metal layer is deposited on the upper surface of the interlayer film 02 of silicon dioxide in fig. 3 in the second step, the top metal layer is etched in the third step, and the metal portions on the upper surface of the interlayer film left after etching are a pad 01 and a protection pattern 07.
In general, in semiconductor manufacturing, a protection pattern functions as a mask (hard mask) for protecting an underlying metal fuse. The protection pattern 07 of the present invention is to avoid the risk that the metal fuse is etched first due to the etching rate of silicon dioxide being faster than that of titanium nitride during etching. The existence of the protection pattern enables the protection pattern to be etched together when the welding pad is etched, so that the lower-layer metal fuse is protected.
Further preferably, in this embodiment, the method for forming the pad and the protection pattern in step three includes: (1) suspending photoresist on the titanium nitride layer on the upper surface of the top metal layer; (2) then carrying out exposure and development; exposing and developing the photoresist according to the size and the position of a welding pad and a protection pattern defined in the layout; (3) forming an etching window of the welding pad graph and an etching window of the protection graph, namely transferring the photoetching graphs of the welding pad graph and the protection graph to the upper surface of the top metal layer according to the layout; (4) and etching the top metal layer according to the photoetching pattern of the etching window, and taking the interlayer film as an etching stop layer. Namely, the top metal layer is etched until the upper surface of the interlayer film is exposed.
Depositing a passivation layer on the welding pad and the protection pattern, and defining a passivation layer etching window above the welding pad 01 and above the protection pattern 07; as shown in fig. 4, fig. 4 is a schematic structural view illustrating the formation of an etching window over the bonding pad and over the protection pattern according to the present invention. Since the metal fuse generates a product when it is blown, a short circuit phenomenon is generated in order to prevent the generated product from being aggregated. In the present invention, preferably, the critical dimension of the protection pattern 07 is smaller than the critical dimension of the metal fuse 05; the passivation etch window 09 defined over the protection pattern 07 is larger than the metal fuse 05 to ensure that a released via is connected to the metal fuse 05. The passivation layer window defined in the step is a graph of the passivation layer window designed according to the layout, and the graph is transferred to the upper parts of the metal fuse and the welding pad by using photoresist.
Preferably, in the fourth step of the present invention, the method for defining the etching window above the pad and above the protection pattern includes: (1) continuously depositing a passivation layer on the upper surface of the welding pad, the upper surface of the protection pattern and the upper surface of the interlayer film exposed outside; the deposited passivation layer covers the upper surfaces of the bonding pad and the protection pattern, as shown in fig. 4, and simultaneously covers the upper surface of the original interlayer film exposed outside; (2) suspending photoresist on the upper surface of the deposited passivation layer; (3) and exposing and developing the photoresist to form an etching window, forming an etching window 08 above the welding pad 01, and forming an etching window 09 above the dummy pattern 07.
In this embodiment, preferably, the width of the etching window 09 of the protection pattern defined in step four determines the width of a subsequent opening window for the metal fuse 05, and the passivation layer etching window 09 defined above the protection pattern 07 is larger than the metal fuse 05. The passivation layer and the interlayer film are subsequently etched along the sidewalls of the etch window 09.
And fifthly, etching according to the etching window to remove the passivation layer and the titanium nitride on the upper surface of the bonding pad, and opening windows on the left and right of the metal fuse to release products generated when the metal fuse is blown. As shown in fig. 5, fig. 5 is a schematic structural view illustrating the removal of the titanium nitride on the bonding pad and the windowing of the left and right sides of the metal fuse according to the present invention. In the step four, the passivation layer above the welding pad 01 and the passivation layer above the protection pattern 07 are etched according to the etching window in the step four. Since the pad 01 and the dummy pattern 07 are formed by etching the top metal layer, the heights of the pad 01 and the dummy pattern are consistent.
When the passivation layer above the bonding pad is etched, the passivation layer above the protection pattern 07 is also etched synchronously, and at this stage, the passivation layer is etched, so that the etching rates are consistent. And when the etching is carried out to the upper surface of the welding pad, removing the titanium nitride on the upper surface of the welding pad, and simultaneously removing the titanium nitride on the upper surface of the protective pattern. Because the etching rate of the silicon dioxide is higher than that of the titanium nitride, the depth of etching the silicon dioxide passivation layer is greater than the thickness of etching the titanium nitride when the titanium nitride is etched, so that after all the titanium nitride on the upper surface of the bonding pad is removed, all the titanium nitride on the upper surface of the protective pattern is removed, meanwhile, in the etching window of the protective pattern, the passivation layers and the interlayer films on the left side and the right side of the protective pattern are etched, and the interlayer film below the protective pattern and between the metal fuses is not etched. Thus protecting the integrity of the middle section of the metal fuse. On the other hand, as shown in fig. 5, windows are opened on the left and right sides of the metal fuse 05, respectively, and a via is connected to the metal fuse.
Preferably, the width of the window opened on the left and right of the metal fuse in the fifth step is larger than the width of the etching window of the protection pattern in the fourth step, and the size of the protection pattern is smaller than that of the metal fuse. As shown in fig. 5, during etching, etching is performed along the sidewall of the etching window of the protection pattern, and the passivation layer and the interlayer film on both sides of the metal fuse are etched to expose both sides of the metal fuse.
Preferably, in the process of opening the windows left and right of the metal fuse in the fifth step, the left and right sides of the upper surface of the metal fuse are partially etched. As can be seen from fig. 5, both sides of the upper surface of the metal fuse 05 are partially removed at the same time as the one-step etching. Meanwhile, the product generated when the metal fuse is blown can be released in time, so as to avoid gathering to form short circuit in situ.
In summary, the present invention utilizes the original pad lithography and etching, and the specific top metal layer protection pattern to achieve the purpose of protecting the metal fuse and windowing the metal fuse, thereby reducing the cost and satisfying the application of customers. The dummy pattern is mask-like to protect the underlying metal fuse, but opens windows at the left and right edges of the metal fuse to allow for the timely release of the products generated when the metal fuse is blown, so as to prevent the build-up from forming a short circuit in situ. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (8)
1. A method for preventing a metal fuse from being over-etched is characterized by at least comprising the following steps:
providing an interlayer film, wherein a metal fuse is arranged in the interlayer film;
secondly, forming a top metal layer on the interlayer film, wherein the upper surface and the lower surface of the top metal layer are respectively provided with a titanium nitride layer;
etching the top metal layer to form a welding pad and a protection pattern positioned above the metal fuse wire; the critical dimension of the protection pattern is smaller than that of the metal fuse;
depositing a passivation layer on the welding pad and the protection pattern, and photoetching and defining an etching window above the welding pad and the protection pattern;
and fifthly, etching according to the etching window to remove the titanium nitride on the upper surface of the bonding pad, and opening windows on the left and right of the metal fuse to release products generated when the metal fuse is blown while protecting the lower metal fuse by using the protection pattern as a mask.
2. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: in the first step, the interlayer film layer is made of silicon dioxide, and the metal fuse is of a titanium nitride-metal-titanium nitride laminated structure.
3. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: and in the second step, the top metal layer is made of aluminum or aluminum-copper alloy.
4. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: the method for forming the welding pad and the protection pattern in the third step comprises the following steps: (1) suspending photoresist on the titanium nitride layer on the upper surface of the top metal layer; (2) then carrying out exposure and development; (3) forming an etching window of the welding pad pattern and an etching window of the protection pattern; (4) and etching the top metal layer according to the etching window, and taking the interlayer film as an etching stop layer.
5. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: the method for defining the etching window above the welding pad and the protective pattern in the fourth step comprises the following steps: (1) depositing a passivation layer on the upper surface of the bonding pad, the upper surface of the protection pattern and the upper surface of the interlayer film exposed outside; (2) suspending photoresist on the upper surface of the deposited passivation layer; (3) and exposing and developing the photoresist to form an etching window.
6. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: and fifthly, the width of the windows opened on the left and the right of the metal fuse is larger than that of the metal fuse.
7. The method for avoiding the over-etching of the metal fuse as claimed in claim 1, wherein: and fifthly, partially etching the left side and the right side of the upper surface of the metal fuse in the process of opening the windows left and right of the metal fuse.
8. The method for avoiding the over-etching of the metal fuse as claimed in claim 2, wherein: the metal in the laminated structure of the metal fuse is made of aluminum or aluminum-copper alloy.
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| CN201910144770.6A CN109887901B (en) | 2019-02-27 | 2019-02-27 | Method for preventing metal fuse from being over-etched |
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| CN201910144770.6A CN109887901B (en) | 2019-02-27 | 2019-02-27 | Method for preventing metal fuse from being over-etched |
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| CN109887901B true CN109887901B (en) | 2020-11-20 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6025214A (en) * | 1995-06-26 | 2000-02-15 | Alliance Semiconductor Corporation | Fusible link structure for semiconductor devices |
| KR20080047666A (en) * | 2006-11-27 | 2008-05-30 | 동부일렉트로닉스 주식회사 | Method for fabricating a semiconductor including a fuse |
| CN103390578A (en) * | 2012-05-11 | 2013-11-13 | 上海华虹Nec电子有限公司 | Manufacturing method for metal fuse |
| CN104576603A (en) * | 2013-10-28 | 2015-04-29 | 北大方正集团有限公司 | Integrated circuit including laser fuse wire and manufacturing method thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999019905A1 (en) * | 1997-10-13 | 1999-04-22 | Fujitsu Limited | Semiconductor device having fuse and fabrication method thereof |
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2019
- 2019-02-27 CN CN201910144770.6A patent/CN109887901B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6025214A (en) * | 1995-06-26 | 2000-02-15 | Alliance Semiconductor Corporation | Fusible link structure for semiconductor devices |
| KR20080047666A (en) * | 2006-11-27 | 2008-05-30 | 동부일렉트로닉스 주식회사 | Method for fabricating a semiconductor including a fuse |
| CN103390578A (en) * | 2012-05-11 | 2013-11-13 | 上海华虹Nec电子有限公司 | Manufacturing method for metal fuse |
| CN104576603A (en) * | 2013-10-28 | 2015-04-29 | 北大方正集团有限公司 | Integrated circuit including laser fuse wire and manufacturing method thereof |
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