TWI406341B - Decapsulation method of chip stacked package - Google Patents

Abstract

Disclosed is a decapsulation method of chip stacked package. A chip stacked package is bound by an acid-proof tape and immersed in an acid solution. The molding compound and die-bonding layer are dissolved by acid-boiling until a plurality of chips are exposed and separated but still bound by the acid-proof tape. Accordingly, there can be stayed its original chip stacking sequence after taking out the chips to perform failure analysis.

Description

Open method of wafer stack package structure

The present invention relates to a method for processing a semiconductor device, and more particularly to a method of opening a wafer stack package structure.

In modern assembly technology, multi-wafer stacked package configurations have been widely used in a variety of different memory IC products. Because of the high density and low cost of multi-wafer stacked package construction, several different forms of multi-wafer stacked package configurations, such as two wafers (2-die), four wafers (4-die) and eight The stack of 8-die is used as the main part of the memory product. A major challenge is the complexity of the manufacturing process, so the importance of failure analysis (FA) is also enhanced to detect defects in the manufacturing process. However, for a FA engineer, in order to be able to accurately identify a defective wafer in a plurality of wafers of a wafer stack package structure, an "opening" (or may be referred to as decapsulation) is required ( Decapsulation) job. How to confirm the original order of the wafer after the wafer is scattered becomes an important key to finding possible problems in the fabrication process.

The conventional opening technique uses an acid boiling method in which the package structure is directly introduced into an acidic solution, and the immersion is boiled for a period of time to dissolve the encapsulant of the package structure, so that the wafer originally sealed in the package structure is detached. When the opening of the wafer stacking and packaging structure is also subjected to the acid boiling method, since the sealing body is dissolved, the plurality of wafers which have been lost by the sealing body flow freely in the acidic solution, thereby confusing the original stacking order of each wafer. In addition, each wafer has the same appearance, resulting in the inability to discern defective wafers from the dispersed wafers, thus delaying subsequent failure analysis. Moreover, the wafer arbitrarily flows within the acidic solution, and it is also prone to the case where the wafers collide with each other to damage the surface of the wafer.

In addition, another method for opening the chip package structure has been proposed, such as the method of quickly taking out a semiconductor wafer from a plastic package, as disclosed in Patent Publication No. 442933, and also for opening a package structure for packaging a single wafer. The wafer sealed in the plastic package is removed without the use of a chemical treatment. First, the wafer formed with the plastic package protection is heated, so that the plastic package begins to embrittle due to heat. Next, the two ends of the plastic package are clamped by the two clamps, and at the same time, a carrier is prepared under the plastic package for carrying the wafer. Thereafter, the two clamps are twisted in opposite directions, causing the heated plastic package to be broken by torque, thereby causing the wafer to naturally fall into the carrier located below. However, since the plastic package is directly damaged by external application of force, the wafer located inside thereof is taken out, and it is easy to directly damage the wafer except when twisted plastic package, and may be damaged by collision after the wafer is naturally dropped to the carrier. If the above-described uncovering method is applied to the wafer stacking and packaging structure, the wafer in the stacked type is more susceptible to external torque and directly damaged, and it is impossible to discern which is after the wafer is dropped and scattered to the carrier. Defective wafer.

In view of the above, the main object of the present invention is to provide a method for opening a wafer stack package structure, which can maintain the original stacking order of the wafer to facilitate the failure analysis.

A second object of the present invention is to provide a method for opening a wafer stack package structure which can prevent the wafer from being strongly moved and damaged in an acidic solution to keep the surface of the wafer intact.

The object of the present invention and solving the technical problems thereof are achieved by the following technical solutions. The invention discloses a method for opening a wafer stack package structure, which mainly comprises: providing a wafer stack package structure comprising a gel body, a plurality of wafers sealed in the sealant body and at least one die bonder bonding the wafers a layer, wherein the plurality of wafers are stacked on each other. The wafer stack package structure is bundled with an acid resistant strap. Thereafter, the wafer stack package structure is immersed in the acid-resistant ribbon to an acidic solution. The encapsulant and the adhesive layer of the wafer stack package structure are dissolved in the acidic solution by acid boiling until the wafers are exposed, scattered and still bound by the acid-resistant strap to hold the wafers. The stacking order is unchanged. Finally, the wafers bound by the acid resistant strap are removed.

The object of the present invention and solving the technical problems thereof can be further achieved by the following technical measures.

In the opening method of the wafer stack package structure described above, the material of the acid-resistant strap is Teflon.

In the opening method of the wafer stack package structure described above, the acid-resistant strap may be bundled in a cross and have a tie point on the top surface of the sealant.

In the opening method of the wafer stack package structure described above, the wafers can be taken out by the splicing point in the above-mentioned taking-out step.

In the opening method of the wafer stack package structure described above, the tie point may be a bow tie.

In the aforementioned opening method of the wafer stack package structure, the acid-resistant strap system may have stretch elasticity.

It can be seen from the above technical solutions that the method for opening the wafer stack package structure of the present invention has the following advantages and effects:

1. The wafer stacking package structure and the immersion in an acidic solution can be used as a technical means for dissolving the wafer in the acid-boiling manner in the process of dissolving the sealant and the die layer of the wafer stack package structure. The movement does not leave. Therefore, after the wafer is taken out, the original stacking order of the wafer can be maintained to facilitate the failure analysis.

Second, the chip stacking package structure can be bundled with an acid-resistant strap as one of the technical means. When the sealant is dissolved in the acidic solution, the wafer can be prevented from colliding and being damaged in an acidic solution, so as to keep the surface of the wafer intact. .

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings in which FIG. The components and combinations related to this case, the components shown in the figure are not drawn in proportion to the actual number, shape and size of the actual implementation. Some size ratios are proportional to other related sizes or have been exaggerated or simplified to provide clearer description of. The actual number, shape and size ratio of the implementation is an optional design, and the detailed component layout may be more complicated.

According to a first embodiment of the present invention, a method for opening a wafer stack package structure is illustrated in the block diagram of FIG. 1 , a cross-sectional view of the components in the opening process of FIGS. 2A to 2F, and a third diagram. A schematic view of the acid solution taken out of the wafer bundled with the acid-resistant strap. According to FIG. 1 , the method for opening the wafer stack package structure mainly comprises the following steps: “Providing a wafer stack package structure”, “Step 2 of “binding the wafer stack package structure with an acid-resistant strap”, “Immersion wafer stacking” Step 4 of "Packaging Structure and Acid-Resistant Binding to Acidic Solution", Step 4 of "Dissolving Sealant and Mold Layer by Acid Boiling" and Step 5 of "Removing Wafer Bundled by Acid-Resistant Bundle", detailed steps Referring to Figures 2A through 2F, the description is as follows.

Referring to FIG. 2A, a wafer stack package structure 10 is provided in the first step, which comprises a glue body 11, a plurality of wafers 12 sealed in the sealant 11 and at least one die bond adhered to the wafers 12. The layer 13 is in a stacked state, and the wafer 12 is adhered by the die layer 13. The die layer 13 can be a die attach material (DAM). The round stage is preformed on the back side of the wafer. In detail, the wafer stack package structure 10 can further include a substrate 14 for carrying the wafers 12, and the bottommost wafer 12 is bonded to the substrate 14 by an adhesive material 15 to complete The wafer stack on the substrate 14. In a preferred embodiment, the encapsulant 11 is formed on the substrate 14 and completely covers the wafer 12, the adhesive layer 13 and the adhesive material 15. In this embodiment, the wafer stack package structure 10 has been subjected to electrical failure analysis (EFA) measurement, and one of the wafers 12 is measured as a defective wafer 12A, and the The location of the defective wafer 12A. For example, the wafers of the wafers 12 stacked in the second layer (in a stacking direction from the bottom up). The term "electrical failure analysis" refers to the use of electrical methods for failure analysis, such as measuring current, EMMI, and wafer map determination. As in the conventional acid boiling method, a plurality of wafers are scattered and the correct defective wafer cannot be directly taken out for analysis and inspection.

Step 2 Referring to Figure 2B, the wafer stack package structure 10 is bundled with an acid resistant strap 20. More specifically, the acid-resistant strap 20 is attached to the surface of the sealant 11 of the wafer stack package structure 10, and the term "attach-fixed" means that the acid-resistant strap 20 is tightly bound. The ground surface is attached to the surface of the sealant 11 and is not slidable or loose, and does not need to be directly adhered to the surface of the sealant 11. In a preferred form, the acid resistant strap 20 can be bundled in a cross and has a tie point 21 on the top surface of the sealant 11. Specifically, the term "cross-bundling" means that the acid-resistant strap 20 is first crossed on the bottom surface of the wafer-stacked package structure 10, and the bottom surface of the wafer-stacked package structure 10 is along the wafer. The stacked package structure 10 is bundled upwards, and the acid-resistant strap 20 is cross-shaped on the top surface of the sealant 11 to form the tie point 21 in a knotted manner. Therefore, the four sides of the wafer stack package structure 10 can be firmly bundled to prevent the occurrence of detachment or tilt in the subsequent step, and does not affect the dissolution of the sealant 11 by the acidic solution in the subsequent step. Additionally, the tie point 21 can be a bow tie to facilitate removal of the acid resistant strap 20 after removal of the sealant. Alternatively, the knot 21 may be selected from other forms of slip knots, such as flat knots, tie knots, double half knots, etc., to provide an easy release effect without affecting the firmness of the tie point 21 itself. In a preferred embodiment, the acid-resistant strap 20 is made of Teflon. The chemical and physical properties of the Teflon itself resist high temperature and strong acid and alkali, and the texture is soft and smooth. . In a variant, the material of the acid-resistant strap 20 may also be selected from one of polyethylene terephthalate (PET) and polyvinyl chloride (PVC), or other materials having high/low temperature resistance. Material for corrosion and corrosion resistance.

Step 3 Referring to FIG. 2C, the wafer stack package structure 10 that has been bundled by the acid-resistant strap 20 is placed in an acidic solution 30, so that the wafer stack package structure 10 and the acid-resistant strap 20 are immersed in The acidic solution 30 is in the solution. The acidic solution 30 can comprise fuming nitric acid to dissolve the encapsulant but retain the integrity of the semiconductor wafer. In the present embodiment, the acidic solution 30 can be stored in an acid-resistant container 40. The material of the acid-resistant container 40 can be selected from glass or other materials resistant to high/low temperature and acid and alkali, usually the acid-resistant container. The 40 series is preferably made of glassware. In addition, the acidic solution 30 can be preheated to a certain temperature, for example, 70-90 degrees Celsius, to shorten the overall process time.

Step 4, as shown in FIGS. 2D and 2E, the sealant 11 and the die layer 13 of the wafer stack package structure 10 are dissolved in the acid solution in an acid-boiling manner in the acid-resistant container 40. 30 inside. In a preferred embodiment, after the acid stack solution 30 is placed in the wafer stack package structure 10, the acidic solution 30 can be continuously heated to provide the acidic solution 30 with a preferred activity for dissolving the sealant. In addition, since the sealant 11, the adhesive layer 13 and the adhesive material 15 both have a resin material soluble in the acidic solution 30, the sealant 11, the adhesive layer 13 and the adhesive material are in this step. 15 will gradually dissolve in the acidic solution 30, but will not corrode the wafer 12 and the substrate 14. In particular, as shown in FIG. 2E, the acid boiling time of the wafer stack package structure 10 should be such that the wafers 12 are exposed, scattered, and still bound by the acid resistant strap 20 to maintain the stack of wafers 12. The order is unchanged, so in the present embodiment, the defective wafer 12A is still the wafer stacked on the second layer of the wafers 12. Specifically, after the encapsulant 11 is dissolved, the overall volume is reduced, but the acid-resistant strap 20 can still bind the wafer 12 and the substrate 14, and the wafers 12 are not lost due to the encapsulant 11 The coating is randomly floated and flows into the acidic solution 30. In a preferred embodiment, the acid-resistant strap 20 can have elastic elasticity, so that after the sealant 11, the adhesive layer 13 and the adhesive material 15 are dissolved, the acid-resistant strap 20 can be appropriately narrowed and bundled. Space, the wafer 12 and the substrate 14 can still be tightly and firmly tied.

Step 5 Referring to FIGS. 2F and 3, after the sealant 11 has been dissolved and the wafers 12 are in a layered state, the wafers 12 bundled by the acid-resistant straps 20 are taken out. Moreover, since the substrate 14 is not dissolved in the acidic solution 30 (as shown in FIG. 2E), when the wafers 12 are removed, the substrate 14 can still be used to carry the wafers 12 that have been dispersed. (Including the defective wafer 12A), the order of arrangement of the wafer stacks remains unchanged or confusing. Preferably, in the step of taking out the wafers 12, the wafers 12 can be taken out by the node points 21. Since the tie point 21 formed by the acid-resistant strap 20 is located on the top surface of the sealant 11, it helps the operator to initially identify the stacking sequence of the wafers 12 after taking out the wafers 12. In addition, the operator can also untie the tie point 21 above the wafers 12, that is, the acid-resistant strap 20 can be easily removed without performing an additional flipping action, so the wafers 12 are before being soaked. After being taken out, it can maintain its original stacking order.

In summary, in the present invention, the wafer stack package structure 10 can be bundled with the acid-resistant strap 20 and immersed in the acidic solution 30 as one of the technical means, the wafer stack package structure in the acid boiling process. The dissolution of the sealant 11 and the die layer 13 does not cause the wafers 12 to be separated. Therefore, after the wafers 12 are taken out of the acidic solution 30, the original stacking order of the wafers 12 can be maintained, thereby facilitating the operator to perform subsequent failure analysis (FA), in addition to making the operator easy. In addition to identification, the overall inspection time can also be shortened. In addition, after the encapsulant 11 is dissolved, the acid-resistant strap 20 is still effectively bound to the wafers 12 so as not to be scattered, so that the wafers 12 can be prevented from being strongly collided and damaged in the acidic solution 30 to maintain The wafers 12 have a complete surface.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention. Any simple modifications, equivalent changes and modifications made without departing from the technical scope of the present invention are still within the technical scope of the present invention.

Step 1 provides a wafer stack package structure

Step 2 Bundle wafer package structure with acid-resistant strap

Step 3 Soak the wafer stack package structure and acid-resistant strap to the acidic solution

Step 4 Dissolve the sealant and the adhesive layer by acid boiling

Step 5 Remove the wafer bundled with the acid-resistant strap

10. . . Wafer stack package construction

11. . . Sealant

12. . . Wafer

12A. . . Defective wafer

13. . . Binder layer

14. . . Substrate

15. . . Adhesive material

20. . . Acid resistant strap

twenty one. . . Tie point

30. . . Acid solution

40. . . Acid resistant container

1 is a flow block diagram of a method of opening a wafer stack package structure in accordance with an embodiment of the present invention.

2A to 2F are views showing a cross-sectional view of an element in a process of opening a lid according to a method of opening a wafer package package according to an embodiment of the present invention.

Fig. 3 is a perspective view showing the method of opening a wafer stack package according to an embodiment of the present invention, after the wafer is bound by an acid-resistant strap.

12. . . Wafer

12A. . . Defective wafer

14. . . Substrate

20. . . Acid resistant strap

30. . . Acid solution

40. . . Acid resistant container

Claims (6)

A method for opening a wafer stack package structure, comprising: providing a wafer stack package structure comprising a gel, a plurality of wafers sealed in the sealant body and at least one adhesive layer adhered to the wafers, wherein The wafers are stacked on each other; the wafer stack package structure is bundled with an acid-resistant strap; the wafer stack package structure and the acid-resistant strap are immersed in an acidic solution; and the wafer stack package structure is acid-boiling The sealant and the adhesive layer are dissolved in the acidic solution until the wafers are exposed, scattered and still bound by the acid-resistant strap to keep the stacking order of the wafers unchanged; and the acid-resistant bundle is taken out The bundles are bundled with the wafers. The method for opening a wafer stack package structure according to claim 1, wherein the material of the acid-resistant strap is Teflon. The method of opening a wafer stack package according to claim 1 or 2, wherein the acid-resistant strap is bundled with a cross and has a tie point on a top surface of the sealant. The method of opening a wafer stack package structure according to claim 3, wherein the wafer is taken out by the splicing point in the removing step. A method of opening a wafer stack package structure according to claim 3, wherein the tie point is a bow. A method of opening a wafer stack package structure according to claim 1 or 2, wherein the acid-resistant strap has elasticity.