Method for testing interface cohesiveness of photosensitive polyimide photoresist material

Abstract

The invention relates to the technical field of photoresist, in particular to a method for testing interface cohesiveness of a photosensitive polyimide photoresist material. The invention discloses a method for testing the interface cohesiveness of a photosensitive polyimide photoresist material. The method comprises the following steps: S1, preparing a photoresist wet film on the surface of a substrate by utilizing photosensitive polyimide photoresist; s2, preparing a photoetching pattern on the photoresist wet film through a photoetching development technology; s3, carrying out curing treatment on the substrate comprising the photoetching pattern to obtain a photoresist film; s4, a push broach is utilized to move towards the photoresist film along the surface of the substrate, stress data and displacement data of the push broach are collected, and the interface bonding strength of the photoresist film and the substrate is calculated according to the stress data and the displacement data. The embodiment of the invention provides a method for testing the bonding property of a photosensitive polyimide photoresist material interface. The bonding strength of photoresist can be accurately tested.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, in particular to a method for testing the interface adhesion of a photosensitive polyimide photoresist material. Background Art

[0002] Photosensitive polyimide (PSPI), a photoresist material, is a key material in integrated circuit packaging and is widely used in the construction of IC chips, device stress buffers, α-particle shielding layers, chip passivation layers, and interlayer dielectric insulation layers. Interfacial adhesion strength is a core performance indicator of PSPI materials in microelectronic packaging, directly impacting device reliability, process efficiency, and cost control. In advanced packaging, PSPI must securely bond to a variety of substrate materials (such as aluminum, silicon nitride, copper, and epoxy molding compound). Insufficient interfacial adhesion can lead to delamination or warping, which can cause package failure, especially in high-stress scenarios. However, evaluating the interfacial adhesion performance of PSPI materials is crucial for evaluating the quality of photoresist packaging. Currently, interfacial adhesion testing of PSPI materials primarily relies on the 100-grid test and the pull-off test. The 100-grid test uses a 100-grid knife to draw across the photoresist sample with a certain pressure, determining the photoresist's adhesion strength based on the number and quality of the grids. The Baige test method is simple and can only be used to qualitatively assess the interfacial bonding strength of photoresist materials, but it is difficult to quantitatively assess the interfacial bonding strength of photoresist materials. The pull-off test uses epoxy resin as an adhesive and a universal mechanical testing machine to measure the interfacial bonding strength of photoresist materials and different substrates. Because the interfacial bonding strength of photoresist / substrate is generally higher than that of epoxy resin / photoresist, the pull-off test results in failure at the epoxy resin / photoresist interface rather than the photoresist / substrate interface, making it difficult to accurately measure the interfacial bonding strength between photoresist and substrate. Therefore, it is particularly urgent to develop an accurate test method for the interfacial bonding properties of photosensitive polyimide photoresist materials. Summary of the Invention

[0003] The embodiment of the present invention provides a method for testing the interface adhesion of a photosensitive polyimide photoresist material, which can accurately test the bonding strength of the photoresist.

[0004] An embodiment of the present invention provides a method for testing the interfacial adhesion of a photosensitive polyimide photoresist material, comprising:

[0005] S1, preparing a photoresist wet film on the substrate surface using a photosensitive polyimide photoresist;

[0006] S2, preparing a photolithographic pattern on the photoresist wet film by photolithographic development technology;

[0007] S3, curing the substrate including the photoresist pattern to obtain a photoresist film;

[0008] S4, using a push knife to move along the surface of the substrate toward the photoresist film, collecting force data and displacement data of the push knife, and calculating the interface bonding strength between the photoresist film and the substrate based on the force data and the displacement data.

[0009] In a possible design, in S4 , the push knife is set to move at a rate of 90 to 110 μm / s.

[0010] In a possible design, in S4, the distance between the pusher and the substrate surface is 8% to 12% of the thickness of the photoresist film.

[0011] In a possible design, in S4 , the size of the push blade is 245 μm.

[0012] In one possible design, S1 includes:

[0013] Spin coating photoresist on the surface of the substrate using a spin coating process;

[0014] The spin-coated photoresist is pre-baked to obtain a photoresist wet film.

[0015] In one possible design, the process parameters of the spin coating process are as follows:

[0016] Spin coating was performed at the following parameters: 200 rpm / 10 s, 500 rpm / 10 s, 1000 rpm / 20 s, and 1500 rpm / 30 s;

[0017] The temperature of the pre-baking treatment is 100-120° C., and the time of the pre-baking treatment is 220-240 seconds.

[0018] In one possible design, the process parameters of the photolithography development technology include:

[0019] Using 280~320mJ / cm 2 Expose to light for 25 to 35 minutes.

[0020] In one possible design, the curing process includes a treatment at 320-360° C. in a nitrogen environment for 55-65 minutes.

[0021] In one possible design, the substrate includes a Si wafer, a sputtered SiO2, Si3N4, Ti, Al, Cu silicon wafer, etc., and has a size of 4 inches.

[0022] In a possible design, the photosensitive polyimide photoresist has a viscosity of 3600 cp and a solid content of 30%.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] The present invention does not require additional epoxy resin glue as an adhesive layer, thus shortening the interface adhesion test cycle;

[0025] In the present invention, the push knife directly acts on the photoresist material, thereby realizing accurate testing of the adhesion force between the photoresist material and the substrate interface;

[0026] The photoresist material interface adhesion performance preparation test scheme proposed in the present invention can be used in other polymer material systems, and the scheme has universality and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1a The microscopic morphology and corresponding dimensions of a long strip photoresist material before interface bonding strength test provided by an embodiment of the present invention;

[0029] Figure 1b The microscopic morphology and corresponding dimensions of a strip of photoresist material after interface bonding strength testing provided by an embodiment of the present invention;

[0030] Figure 2 This is a real-time force-displacement curve during a test of the interfacial bonding strength of a long strip photoresist material provided by an embodiment of the present invention;

[0031] Figure 3 The microscopic morphology and corresponding dimensions of a cylindrical photoresist material before and after interface bonding strength testing provided by an embodiment of the present invention are shown;

[0032] Figure 4 This is a force-displacement curve during the interface bonding strength test between a cylindrical photoresist pattern and a pure Si substrate provided by an embodiment of the present invention;

[0033] Figure 5 The microscopic morphology and corresponding dimensions of a square photoresist material before and after the interface bonding strength test provided by an embodiment of the present invention;

[0034] Figure 6 The figure is a force-displacement curve during the interface bonding strength test between a square photoresist pattern and a pure Si substrate provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] An embodiment of the present invention provides a method for testing the interfacial adhesion of a photosensitive polyimide photoresist material, comprising:

[0037] S1, preparing a photoresist wet film on the substrate surface using a photosensitive polyimide photoresist;

[0038] S2, preparing a photolithographic pattern on the photoresist wet film by photolithographic development technology;

[0039] S3, curing the substrate including the photoresist pattern to obtain a photoresist film;

[0040] S4, using a push knife to move along the substrate surface toward the photoresist film, collecting force data and displacement data of the push knife, and calculating the interface bonding strength between the photoresist film and the substrate based on the force data and displacement data.

[0041] In some embodiments of the present invention, in S4 , the push knife is set to move at a rate of 90 to 110 μm / s (for example, 90 μm / s, 95 μm / s, 100 μm / s, 105 μm / s or 110 μm / s).

[0042] In this embodiment, if the push knife speed exceeds the above range, the force applied by the push knife is too large, which may easily cause non-interface damage or stress distribution distortion, causing the failure mode to deviate from the pure shear mode; if the push knife speed is lower than the above range, the test time is too long, resulting in low test efficiency.

[0043] In some embodiments of the present invention, in S4, the distance between the pusher and the substrate surface is 8% to 12% of the thickness of the photoresist film (for example, 8%, 9%, 10%, 11% or 12% of the thickness of the photoresist film).

[0044] In this embodiment, if the distance between the push knife and the substrate is less than the above range, the push knife is too close to the bonding interface, which is likely to generate non-shear stress; if the distance between the push knife and the substrate is greater than the above range, the push knife may partially separate the photoresist film, resulting in a large amount of film residue on the substrate, making it impossible to separate the film and the substrate.

[0045] In some embodiments of the present invention, in S4 , the size of the push blade is 245 μm.

[0046] In this embodiment, the size of the push knife is close to the force-bearing surface of the photoresist film, which can ensure that the bonding interface withstands pure shear force.

[0047] In some embodiments of the present invention, S1 includes:

[0048] Spin coating photoresist on the surface of the substrate using a spin coating process;

[0049] The spin-coated photoresist is pre-baked to obtain a photoresist wet film.

[0050] In some embodiments of the present invention, the process parameters of the spin coating process are as follows:

[0051] Spin coating was performed at the following parameters: 200 rpm / 10 s, 500 rpm / 10 s, 1000 rpm / 20 s, and 1500 rpm / 30 s;

[0052] The temperature of the pre-baking treatment is 100-120° C., and the time of the pre-baking treatment is 220-240 seconds.

[0053] In some embodiments of the present invention, the process parameters of the photolithography development technology include:

[0054] Using 280~320mJ / cm 2 Expose to light for 25 to 35 minutes.

[0055] In some embodiments of the present invention, the curing process comprises curing at 320-360° C. in a nitrogen environment for 55-65 minutes.

[0056] In some embodiments of the present invention, the substrate includes a Si wafer, a sputtered SiO2, Si3N4, Ti, Al, Cu silicon wafer, etc., and has a size of 4 inches.

[0057] In some embodiments of the present invention, the viscosity of the photosensitive polyimide photoresist is 3600 cp and the solid content is 30%.

[0058] In order to more clearly illustrate the technical solutions and advantages of the present invention, several embodiments are described in detail below.

[0059] In the embodiment, the commercial photoresist material is HD-4100 series negative photoresist produced by DuPont Japan, wherein the photoresist viscosity is 3600 cp and the solid content is 30%. The equipment equipped with the pusher is a Dage (UK, now a Nordson) product series: Precision Bond Tester (such as Dage 4000 series).

[0060] Example 1

[0061] In a clean room, 5 g of HD 4100 photoresist was poured onto the center of a 4-inch pure Si wafer and spin-coated according to the set program (200 rpm / 10s-500 rpm / 10s-1000 rpm / 20s-1500 rpm / 30s) to obtain a photoresist wet film;

[0062] The photoresist wet film was placed on a hot plate at 110°C for 230 seconds to remove the solvent inside the photoresist wet film.

[0063] Place the pre-baked photoresist film in the photolithography machine and set the exposure energy to 300mj / cm 2 , exposure for 30 minutes, taking out and developing operation, obtaining a long strip photolithography pattern;

[0064] The exposed and developed photoresist pattern was cured in an N2 atmosphere at 350°C for 60 min to obtain a 10.2 μm thick strip photoresist pattern.

[0065] A long strip of photolithographic pattern with a pure Si sheet was placed in a micro-thruster with a blade width of 245 μm, a blade speed of 100 μm / s, and a blade height of 1 μm from the pure Si substrate. Finally, the interface bonding strength between the photoresist and the pure Si substrate was obtained.

[0066] Figure 1a and Figure 1b The micromorphology and corresponding dimensions of the long strip photoresist material before and after the interface bonding strength test are as follows: the length of the long strip photoresist pattern is 297.45um, the width is 145.21um, and the thickness is 10.2um; after the interface bonding strength test, the width of the long strip photoresist material is 295.91um, and some photoresist material remains, which is mainly attributed to the fact that the knife width is smaller than the size of the long strip photoresist, resulting in photoresist residue.

[0067] Figure 2 This is the real-time force-displacement curve during the interface bonding strength test of the long strip photoresist material. Combined with the curve, it can be seen that the maximum force of the long strip photoresist material is 76.3g, the force-bearing surface of the long strip photoresist material is the side, and the force-bearing surface is 297.45μm×10.2μm. The calculated interface bonding strength between the long strip photoresist material and the pure Si substrate is 24.6MPa.

[0068] Example 2

[0069] Example 2 is basically the same as Example 1, except that in Example 2, a cylindrical photoresist pattern with a thickness of 10.2 μm is obtained after operations such as exposure-development-curing. Other aspects are the same as Example 1.

[0070] Figure 3The micromorphology and corresponding dimensions of the cylindrical photoresist material before and after the interface bonding strength test. The diameter of the cylindrical photoresist pattern is 250um and the thickness is 10.2um. After the interface bonding strength test, the diameter of the cylindrical photoresist pattern is 250um, and the cylindrical photoresist pattern is completely pushed off.

[0071] Figure 4 This is the real-time force-displacement curve during the interface bonding strength test of the long strip photoresist material. Combined with the curve, it can be seen that the maximum force of the long strip photoresist material is 67.3g. The cross-section of the cylindrical photoresist pattern is the force-bearing surface, and the cross-sectional area is 250μm×10.2μm. The calculated interface bonding strength between the cylindrical photoresist pattern and the pure Si substrate is 25.8MPa.

[0072] Example 3

[0073] Example 2 is basically the same as Example 1, except that, in Example 3, a square photoresist pattern with a thickness of 10.2 μm and a width of 200 μm is obtained after exposure-development-curing operations, and the rest is the same as Example 1.

[0074] Figure 5 The microscopic morphology and corresponding dimensions of the square photoresist material before and after the interface strength test. The side length of the square photoresist pattern is 200um and the thickness is 10.2um. After the interface adhesion strength test, the side length of the square photoresist pattern is 200um, and the square photoresist pattern is completely pushed off.

[0075] Figure 6 This is the real-time force-displacement curve during the interface bonding strength test of the square photoresist material. Combined with the curve, it can be seen that the maximum force of the square photoresist material is 54.0g. The cross-section of the square photoresist pattern is the force-bearing surface with a cross-sectional area of ​​200μm×10.2μm. The calculated interface bonding strength between the square photoresist pattern and the pure Si substrate is 25.9MPa.

[0076] Example 4

[0077] The difference from Example 1 is that the spin-coating substrate in Example 2 is a silicon wafer with a SiO2 layer sputtered on the surface, and the rest is the same as Example 1.

[0078] Example 5

[0079] The difference from Example 1 is that the spin-coating substrate in Example 5 is a silicon wafer with a Si3N4 layer sputtered on the surface, and the rest is the same as Example 1.

[0080] Example 6

[0081] The difference from Example 1 is that the spin-coating substrate in Example 6 is a silicon wafer with a Ti layer sputtered on the surface, and the rest is the same as Example 1.

[0082] Example 7

[0083] The difference from Example 1 is that the spin-coating substrate in Example 7 is a silicon wafer with an Al layer sputtered on the surface, and the rest is the same as Example 1.

[0084] Example 8

[0085] The difference from Example 1 is that the spin-coating substrate in Example 8 is a silicon wafer with a Cu layer sputtered on the surface, and the rest is the same as Example 1.

[0086] Comparative Example 1

[0087] Comparative Example 1 is substantially the same as Example 1, except that the distance between the pusher and the substrate is 0.51 μm.

[0088] According to the real-time force-displacement curve, the interfacial bonding strength is 19.5 MPa.

[0089] Comparative Example 2

[0090] Comparative Example 2 is substantially the same as Example 1, except that the distance between the pusher and the substrate is 1.53 μm.

[0091] According to the real-time force-displacement curve, the interfacial bonding strength is 18.7 MPa.

[0092] Comparative Example 3

[0093] Comparative Example 3 is substantially the same as Example 1, except that the pushing speed of the pusher is 70 μm / s.

[0094] According to the real-time force-displacement curve, the interfacial bonding strength is 20.8 MPa.

[0095] Comparative Example 4

[0096] Comparative Example 4 is substantially the same as Example 1, except that the push speed of the pusher is 130 μm / s.

[0097] According to the real-time force-displacement curve, the interfacial bonding strength is 21.2 MPa.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for testing the interfacial adhesion of a photosensitive polyimide photoresist material, characterized in that: include: S1, preparing a photoresist wet film on the substrate surface using a photosensitive polyimide photoresist; S2, preparing a photolithographic pattern on the photoresist wet film by photolithographic development technology; S3, curing the substrate including the photoresist pattern to obtain a photoresist film; S4, using a push knife to move along the surface of the substrate toward the photoresist film, collecting force data and displacement data of the push knife, and calculating the interface bonding strength between the photoresist film and the substrate based on the force data and the displacement data.

2. The testing method according to claim 1, wherein: In S4, the moving speed of the push knife is set to 90-110 μm / s.

3. The testing method according to claim 1, wherein: In S4, the distance between the push knife and the substrate surface is 8% to 12% of the thickness of the photoresist film.

4. The testing method according to claim 1, wherein: In S4 , the size of the push blade is 245 μm.

5. The testing method according to claim 1, wherein: S1 includes: Spin coating photoresist on the surface of the substrate using a spin coating process; The spin-coated photoresist is pre-baked to obtain a photoresist wet film.

6. The testing method according to claim 5, characterized in that: The process parameters of the spin coating process are as follows: Spin coating was performed at the following parameters: 200 rpm / 10 s, 500 rpm / 10 s, 1000 rpm / 20 s, and 1500 rpm / 30 s; The temperature of the pre-baking treatment is 100-120° C., and the time of the pre-baking treatment is 220-240 seconds.

7. The testing method according to claim 1, wherein: The process parameters of the photolithography development technology include: Using 280~320mJ / cm 2 Expose to light for 25 to 35 minutes.

8. The testing method according to claim 1, wherein: The curing treatment includes a treatment at 320-360° C. in a nitrogen environment for 55-65 minutes.

9. The testing method according to claim 1, wherein: The substrate includes Si wafer, sputtered SiO2, Si3N4, Ti, Al, Cu silicon wafer, etc., and the size is 4 inches.

10. The testing method according to claim 1, wherein: The photosensitive polyimide photoresist has a viscosity of 3600 cp and a solid content of 30%.

Images