Substrate PI glue curing adhesion effect testing method

Abstract

The invention discloses a substrate PI glue curing adhesion effect testing method, which comprises the following steps of: scribing a wafer subjected to pretreatment, gluing, developing and curing, scribing a plurality of uniform grids on a gluing surface, firstly attaching a protective film to the surface of the wafer to be tested after the grids are divided through film pasting equipment, and then attaching the protective film to the surface of the wafer to be tested through film pasting equipment; and then the protective film is removed through film tearing operation, the adhesion effect of the PI glue is determined according to the adhesion condition of the grids after film tearing, and the process effect of batch products is verified. By using the method, the problem that the PI adhesive adhesion effect can be exposed only when an actual product is subjected to subsequent scribing, packaging and other processes can be avoided, the quality of batch products can be known in advance, and the method has obvious significance for screening unqualified products in advance, avoiding unnecessary subsequent process resource and time waste and improving the continuity and execution efficiency of the process.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a method for testing the curing adhesion effect of substrate PI adhesive. Background Technology

[0002] Insulated polymer (PI) adhesives are widely used in the manufacturing of integrated circuits and discrete device chips. Timely and effective detection of the adhesion of PI adhesives after curing on chips has always been a technical challenge in the industry. The adhesion of PI adhesives directly affects the reliability, yield, and long-term stability of products. Problems such as PI layer peeling or detachment caused by insufficient adhesion between the PI adhesive and the substrate (e.g., silicon, silicon oxide, silicon nitride, aluminum, copper, silver, etc.) usually only become apparent during subsequent processes (e.g., dicing, packaging), at which point the problems and losses are difficult to remedy.

[0003] Therefore, a standardized, quantifiable, efficient, and easy-to-implement method for testing and verifying the adhesion effect of PI adhesive on a substrate can greatly improve verification efficiency, ensure the quality of subsequent products, and improve the efficiency of continuous production. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art and provide a method for testing the curing and adhesion effect of PI adhesive on substrates. Through sampling tests, the curing and adhesion effect of PI adhesive in batches of products with the same process can be obtained.

[0005] To achieve the above objectives, this invention designs a method for testing the curing adhesion effect of PI adhesive on a substrate, the testing method comprising: S1. Perform pre-coating treatment on the wafer to be tested or verified; S2. Coat the wafer with PI adhesive on a spin coater; S3. Develop the wafer, including using conventional development processes; S4. Curing the wafer, including using conventional curing processes; S5. Divide the PI adhesive coated surface of the wafer into uniform squares according to a fixed size on the dicing machine; S6. When using blue film to attach to the wafer surface, it is generally necessary to ensure that the film application pressure of wafers in the same batch of verification is consistent. S7. Peel off the blue film attached to the wafer surface and characterize the strength of the PI adhesive adhesion by measuring the percentage of PI adhesive squares that are removed after peeling off the blue film.

[0006] Furthermore, the percentage includes the percentage of squares with PI adhesive removed out of the total number of squares, and the pre-coating treatment includes cleaning operations to remove impurities and oven baking to remove moisture from the wafer surface, so as to eliminate or reduce the influence of the wafer surface condition on the verification.

[0007] Furthermore, the curing includes heat curing. Since there are various curing process curves (temperature-time curves) for PI adhesive, and the curing temperature curve also affects the adhesion of the PI adhesive, this invention can also be used to test the influence of different curing curves on the adhesion of PI adhesive.

[0008] Furthermore, the blue film includes flip film, UV film, wafer blue film, SPV224 blue film, KL680 blue film, etc., which are protective films used in semiconductor wafer fabs for wafer cutting or substrate cutting, back grinding, and thinning processes to protect surface circuits. They are generally made of PVC material and may have a PET release film.

[0009] Furthermore, the grid includes squares or rectangles, with length and width dimensions ranging from 0.5 to 3.0 mm respectively.

[0010] Furthermore, the grid includes 1mm*1mm squares.

[0011] Furthermore, the total number of squares is 100, mainly for ease of statistical calculation. Irregularly divided squares on the outer edge of the wafer, or those with an area less than 2 / 3 of the theoretical square area, are not included in the statistics.

[0012] Furthermore, the fixed size of the grid includes 1mm*1.5mm.

[0013] Furthermore, the dicing only penetrates the surface PI film, not the wafer.

[0014] Furthermore, the testing method includes testing and verifying multiple wafers from the same batch at once, and the percentage includes the percentage of the total number of PI adhesive squares that were removed after peeling off the blue film from all the tested wafers out of the total number of squares on all wafers; the speed and force of peeling off the blue film are kept uniform.

[0015] The advantages and beneficial effects of this invention are as follows: This invention performs a dicing process on wafers after pretreatment, coating, development, and curing. The coated surface is diced into several uniform squares. A protective film is first applied to the surface of the wafer after dicing using a film-applying device. Then, the protective film is removed by a peeling operation. The adhesion of the PI adhesive is determined based on the adhesion of the squares after peeling, thus verifying the process effect of the batch product. This method is reasonable and feasible, avoiding the problem that the adhesion effect of the PI adhesive is only exposed during subsequent dicing and packaging processes. This allows for early detection of batch product quality, significantly improving the ability to screen out substandard products, avoid unnecessary waste of subsequent process resources and time, and enhance the continuity and efficiency of the process. Attached Figure Description

[0016] Figure 1This is a flowchart of the substrate PI adhesive curing adhesion effect test method of the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0018] Example 1: In this embodiment, one aluminum substrate and one silicon nitride substrate wafer were selected for testing and measurement, respectively. A method for testing the adhesion effect of PI adhesive on substrates is provided, as follows: Figure 1 As shown, the test method includes: S1. Perform pre-coating treatment on the wafer to be tested or verified; S2. Coat the wafer with PI adhesive on the spin coater. Wafers with different dielectric layers or different types of PI adhesive can be used. The coating should be uniform in thickness. Generally, the thickness can be checked after coating. If the test is normal, proceed to the next step. If it is abnormal, recoat or classify it as a defective product. S3. Develop the wafer, including using conventional development processes; In this embodiment, a developing device sprays developer onto the wafer; the contact time between the developer and the wafer surface is controlled according to a preset developing time; residual developer is removed from the wafer surface using a cleaning device; the developing effect is tested on the cleaned wafer surface; developing parameters are adjusted based on the test results to optimize the developing quality; if the test results meet the preset standards, the wafer is transferred to the subsequent curing process; if the test results do not meet the preset standards, the wafer is re-developed until the requirements are met.

[0019] S4. Curing the wafer, including using conventional curing processes; S5. Divide the PI adhesive coated surface of the wafer into uniform squares according to a fixed size on the dicing machine; S6. When using blue film to attach to the wafer surface, it is generally necessary to ensure that the film application pressure of wafers in the same batch of verification is consistent. S7. Peel off the blue film attached to the wafer surface. The percentage (η) of PI adhesive squares that are removed after peeling off the blue film characterizes the strength of the PI adhesive adhesion. The fewer the number of PI adhesive squares removed or the lower the percentage, the stronger the PI adhesive adhesion. The specific test conclusions here only apply to the corresponding substrate (surface dielectric layer), the corresponding PI adhesive type, and the corresponding pretreatment, coating, developing, curing processes, and square dicing size. The test conclusions are generally not applicable to wafer products under different process conditions, but they can be used for reference or to compare the PI adhesive adhesion effects of different processes. In particular, it is feasible to judge the quality of PI adhesive adhesion in actual processes based on statistical theory through multiple wafers and / or multiple tests. Theoretically, for qualified batches, η=0, and at most does not exceed 1%.

[0020] Preferably, the percentage includes the percentage of squares with PI adhesive removed out of the total number of squares, and the pre-treatment includes cleaning to remove impurities and oven baking to remove moisture from the wafer surface, so as to eliminate or reduce the influence of the wafer surface condition used for verification.

[0021] After pretreatment of the wafer surface, the surface condition is generally confirmed by testing equipment; the processing conditions of the wafer surface are adjusted according to the test results; corresponding processing methods are adopted for different areas of the wafer surface to unify surface characteristics; the surface consistency of the processed wafer is judged through a preset verification process; if the judgment result meets the preset standard, the wafer is transferred to the subsequent coating process; if the judgment result does not meet the preset standard, the wafer is re-treated until the surface condition meets the requirements.

[0022] Preferably, the curing includes heat curing.

[0023] Preferably, the blue film includes flip film, UV film, wafer blue film, SPV224 blue film, KL680 blue film, etc., which are protective films used in semiconductor wafer fabs for wafer dicing or substrate dicing, back-side grinding, and thinning processes to protect surface circuits. They are generally made of PVC material and may have a PET release film. The PI adhesive is polyimide adhesive, and in this embodiment, Toray PW-5000s type adhesive is used.

[0024] In this embodiment, the wafer is heated using a curing device, and the operating conditions of the curing device are controlled according to preset curing temperature and time parameters. The curing state of the wafer surface is monitored in real time using a detection device. The curing parameters are adjusted based on the monitoring results to optimize the curing effect. If the monitoring results meet the preset standards, the wafer is transferred to the subsequent grading process. If the monitoring results do not meet the preset standards, the wafer is re-cured until the requirements are met. The cured wafer is cooled using a cooling device.

[0025] Preferably, the squares include squares or rectangles, with length and width ranging from 0.5 to 3.0 mm respectively. If the size is too small, the PI adhesive layer will be easily damaged during dicing, making the final percentage of quantity meaningless. If the size is too large, the effect of some local poor adhesion will be easily masked by the effect of the surrounding strong adhesion. Moreover, due to the excessively large size, the total number of squares will be significantly reduced, and the percentage of PI adhesive squares that have been removed will also lack statistical significance.

[0026] Preferably, the grid described in this embodiment includes 1mm*1mm grids.

[0027] Preferably, the dicing cutter only cuts through the surface PI film and not through the wafer. The dicing depth is generally equal to the thickness of the PI film, and the debris generated during the dicing process is removed by cleaning equipment (such as air blower).

[0028] Sample test results show that the percentage η of the number of squares that were removed was 0% for both aluminum and silicon nitride substrates.

[0029] Example 2: The difference from Example 1 is that the fixed size of the squares in this example includes 1mm*1.5mm, and the percentage η of the number of squares that are removed is still 0% for both aluminum and silicon nitride substrates.

[0030] Example 3: The difference from Example 1 is that the total number of squares is 100. Setting 100 squares facilitates statistical analysis, and their length and width dimensions still range from 0.5 to 3.0 mm. Irregularly divided squares on the outer edge of the wafer, or those with an area less than 2 / 3 of the theoretical square area, are not included in the statistics.

[0031] Example 4: Preferably, the testing method includes testing and verifying multiple wafers from the same batch at once. The percentage includes the percentage of the total number of PI adhesive squares that were peeled off after peeling off the blue film from all tested wafers, relative to the total number of squares on all wafers. In this embodiment, statistical test results from multiple wafers (generally no less than 5) are used to characterize the strength of the PI adhesive adhesion effect of the batch products. The speed and force of peeling off the blue film are kept uniform to avoid uneven damage to the PI adhesive adhesion effect, which could lead to result errors.

[0032] The difference from Example 1 is that five wafers each of two unqualified batches of aluminum substrate and silicon nitride substrate were tested simultaneously, and statistical calculations were performed. The η values ​​were 5% and 13%, respectively, and the basic conclusions were consistent with the actual situation.

[0033] Example 5: To clearly illustrate the feasibility of the method of the present invention, this embodiment was designed. The difference from Embodiment 1 is that in this embodiment, no pretreatment was performed on the two aluminum substrate and silicon nitride substrate wafers. Subsequent processes such as coating and development were directly performed. The actual test results show that the percentages η of the number of squares that were removed from the two types of substrate wafers were 6% and 9%, respectively, which are significantly higher than the percentages after the pretreatment process. That is, without the pretreatment process, the PI adhesive adhesion effect of the wafer will be significantly affected. The test results are consistent with the theoretical analysis, indicating that the method of the present invention is feasible and the conclusion is reasonable.

[0034] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for testing the adhesion effect of PI adhesive on a substrate, characterized in that, The testing method includes: S1. Perform pretreatment on the wafer before coating with adhesive; S2. Coat the wafer with PI adhesive on a spin coater; S3. Develop the wafer; S4. Solidify the wafer; S5. Divide the wafer into uniform squares of a fixed size on the dicing machine; S6. Apply blue film to the wafer surface; S7. Peel off the blue film attached to the wafer surface and characterize the strength of the PI adhesive adhesion by measuring the percentage of PI adhesive squares that are removed after peeling off the blue film.

2. The method for testing the curing adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The percentage includes the percentage of squares with PI glue removed out of the total number of squares, and the pre-treatment for applying glue includes cleaning to remove impurities and baking in an oven to remove moisture from the surface of the disc.

3. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The curing includes heat curing.

4. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The blue film includes flip-chip film, UV film, wafer blue film, SPV224 blue film, and KL680 blue film.

5. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The grid includes squares or rectangles, with length and width dimensions ranging from 0.5 to 3.0 mm respectively.

6. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 5, characterized in that, The grid consists of 1mm x 1mm squares.

7. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 5, characterized in that, The total number of squares is 100.

8. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The fixed dimensions of the grid include 1mm*1.5mm.

9. The method for testing the adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The dicing blade only scratches through the surface PI film, not through the wafer.

10. The method for testing the curing adhesion effect of PI adhesive on a substrate according to claim 1, characterized in that, The testing method includes testing and verifying multiple wafers from the same batch at once. The percentage of quantity includes the percentage of the total number of PI adhesive squares that were removed after peeling off the blue film from all tested wafers out of the total number of squares on all wafers. The speed and force of peeling off the blue film are kept uniform.

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