Method for improving damage to polyimide layer in wafer front surface film tearing process

Abstract

The invention provides a method for improving damage to a polyimide layer in a wafer front surface film tearing process, and the method comprises the steps: 1, providing a wafer, and forming an aluminum liner and a polyimide layer on the wafer; and step 2, arranging a buffer area formed by a material layer with strong adhesive force with the polyimide layer in a film tearing starting area which is used as a film pasted on the front surface of the wafer in the area covered by the polyimide layer. The buffer region formed by the material layer with strong adhesive force with the polyimide layer is arranged in the initial region of the wafer front surface film tearing, so that the damage to the polyimide layer in the wafer front surface film tearing process can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for improving the damage to a polyimide layer caused by a wafer front film tearing process. Background Art

[0002] Currently, in order to improve the reliability of semiconductor products, polyimide is usually used to isolate water vapor and improve the pressure resistance of the product.

[0003] In the back-end process stage, the wafer (silicon wafer with circuits on the front) needs to be thinned on the back before subsequent dicing, bonding and packaging to reduce the package mounting height, reduce the chip package volume, improve the chip's thermal diffusion efficiency, electrical performance, mechanical properties and reduce the amount of dicing processing.

[0004] Before backside thinning is performed, a film is applied to the front side of the wafer to protect the wafer. Before shipment, a film peeling process is required to remove the film (also called blue film) on the front side of the wafer.

[0005] like Figure 1 As shown in the upper middle figure, the polyimide layer has strong adhesion to the aluminum liner below, but poor adhesion to the part outside the aluminum liner (usually the silicon nitride layer). Figure 1 As shown in the lower middle figure, the wafer front film tearing process will cause the polyimide layer in the starting area to fall off, thereby reducing the reliability of semiconductor products. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a method for improving the damage to the polyimide layer caused by the wafer front film tearing process, so as to solve the problem of polyimide layer falling off caused by wafer front film tearing in the prior art.

[0007] To achieve the above-mentioned purpose and other related purposes, the present application provides a method for improving the damage to the polyimide layer caused by the wafer front film tearing process, comprising:

[0008] Step 1, providing a wafer, on which an aluminum liner and a polyimide layer are formed;

[0009] Step 2: a buffer zone composed of a material layer with strong adhesion to the polyimide layer is provided in the area covered by the polyimide layer as a starting area for film tearing of the wafer front side film.

[0010] Preferably, the material layer having strong adhesion to the polyimide layer includes an aluminum metal layer.

[0011] Preferably, the buffer zone is composed of a plurality of lines arranged in parallel, and each line is composed of two lines connected end to end at a 90-degree angle.

[0012] Preferably, the length of each line segment is shorter than the length of the cutting path parallel to the line segment.

[0013] Preferably, the lines are arranged at equal intervals, and the intervals are less than or equal to the width of the lines.

[0014] Preferably, the number of lines is 2-5.

[0015] Preferably, after step 2 is completed, a wafer front side film is applied.

[0016] Preferably, after the wafer is filmed on the front side, back side thinning, back side filming, ring cutting / ring removal, dicing and front side film tearing are sequentially performed.

[0017] As described above, the method provided in the present application for improving the damage to the polyimide layer caused by the film tearing process on the front side of the wafer has the following beneficial effects: a buffer zone composed of a material layer with strong adhesion to the polyimide layer is set in the starting area of ​​the film tearing process on the front side of the wafer, which can effectively improve the damage to the polyimide layer caused by the film tearing process on the front side of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram showing damage to the polyimide layer caused by the existing film peeling process;

[0020] Figure 2 A flow chart showing a method for improving the damage to the polyimide layer caused by the wafer front film tearing process provided by an embodiment of the present application;

[0021] Figure 3 A schematic diagram showing a buffer zone provided in a method for improving damage to a polyimide layer caused by a wafer front side film tearing process according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0022] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0027] See also Figure 2 , which shows a flow chart of a method for improving the damage to the polyimide layer caused by the wafer front side film tearing process provided by an embodiment of the present application.

[0028] like Figure 2 As shown, the method for improving the damage to the polyimide layer caused by the wafer front film peeling process includes the following steps:

[0029] Step 1, providing a wafer, on which an aluminum liner and a polyimide layer are formed;

[0030] Step 2: a buffer zone composed of a material layer with strong adhesion to the polyimide layer is provided in the area covered by the polyimide layer as a starting area for film tearing of the wafer front side film.

[0031] In step 1, after an aluminum liner is formed on the wafer, a polyimide layer is formed to isolate moisture and improve the pressure resistance of the wafer.

[0032] In step two, the material layer with strong adhesion to the polyimide layer is preferably the aluminum metal layer, so that the groove and buffer pattern for filling the aluminum liner can be formed on the wafer by the same etching process.

[0033] like Figure 3 As shown, the buffer zone is composed of a plurality of lines arranged in parallel, each line is composed of two lines connected end to end at 90 degrees, and the length of each line is less than the length of the cutting path parallel to it. The lines are arranged at equal intervals, and the interval is less than or equal to the width of the line. The width of the line and the size of the interval between the lines are determined according to the etching process window, and are not specifically limited here. Exemplarily, the number of the lines is 2-5.

[0034] After step 2 is completed, the front side of the wafer is filmed and then the back side is thinned.

[0035] The specific steps of back thinning are to bond the wafer to be processed to the thinning film, and then use vacuum adsorption to adsorb the thinning film and the wafer on it onto the porous ceramic substrate table. The center lines of the inner and outer circular boats of the working surface of the cup-shaped diamond grinding wheel are adjusted to the center position of the wafer. The wafer and the grinding wheel rotate around their respective axes for in-cut grinding.

[0036] Generally, when a wafer is thinned to a certain extent and has a large area, its mechanical strength will be greatly reduced. For example, for an 8-inch wafer, when the wafer thickness is less than 200 microns, the wafer will curl and cannot be transported, transferred or processed. For this reason, the Taiko grinding process is used to thin the back of the wafer. Only the middle part of the wafer is thinned, and the edge of the wafer, which is about 2mm-3mm wide, is not thinned. The remaining edge forms a support ring to maintain the mechanical strength of the entire wafer and prevent the wafer from curling.

[0037] After backside thinning, the wafer is back-filmed and then circumcised to remove excess film.

[0038] For wafers thinned by Taiko grinding, after the ring cutting process, a ring removal process is performed to remove the support ring (Taiko ring) at the edge of the wafer. Exemplarily, the ring removal process is a laser cutting process.

[0039] After the ring cutting / removal process, the dicing process is also included to obtain multiple independent small chips. Then, the front film is torn off. Since the presence of the buffer zone enhances the adhesion between the polyimide layer and the wafer surface, the damage to the polyimide layer caused by the wafer front film tearing process can be significantly improved. Therefore, the present application effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0040] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present application in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0041] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present application.

Claims

1. A method for improving the damage to the polyimide layer caused by the wafer front film tearing process, characterized in that: The method comprises: Step 1, providing a wafer, on which an aluminum liner and a polyimide layer are formed; Step 2: a buffer zone composed of a material layer with strong adhesion to the polyimide layer is provided in the area covered by the polyimide layer as a starting area for film tearing of the wafer front side film.

2. The method according to claim 1, characterized in that: The material layer having strong adhesion to the polyimide layer comprises an aluminum metal layer.

3. The method according to claim 1, characterized in that The buffer zone is composed of a plurality of lines arranged in parallel, and each of the lines is composed of two lines connected end to end at a 90-degree angle.

4. The method according to claim 3, characterized in that The length of each line segment is shorter than the length of the cutting path parallel to the line segment.

5. The method according to claim 3, characterized in that: The lines are arranged at equal intervals, and the intervals are less than or equal to the width of the lines.

6. The method according to claim 3, characterized in that: The number of the lines is 2-5.

7. The method according to claim 1, characterized in that After the step 2 is completed, the wafer front side is filmed.

8. The method according to claim 7, characterized in that After the wafer is filmed on the front side, back side thinning, back side filming, ring cutting / ring removal, dicing and front side film tearing are sequentially performed.

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