Photosensitive film footing removing method based on plasma processing

Abstract

The invention relates to a photosensitive film footing removing method based on plasma processing, and belongs to the technical field of printed circuit boards. Comprising the following steps: plasma treatment: carrying out plasma treatment on a developed glass substrate, and removing a photosensitive film footing at the edge of a circuit; pattern electroplating: performing pattern electroplating on the glass substrate subjected to plasma treatment to form a metal circuit; stripping the film: removing the redundant photosensitive film on the electroplated glass substrate; and etching: etching the bottom base copper to form a refined circuit. According to the invention, the photosensitive film is formed by excitation of an inductively coupled plasma device, photosensitive film residues can be effectively removed through dual effects of physical bombardment and chemical reaction, and meanwhile, the surface of a substrate is not damaged, so that the problems of rough circuit edge, non-uniform line width and the like in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to a method for removing the base feet of a photosensitive film based on plasma treatment, belonging to the technical field of printed circuit boards. Background Art

[0002] In the manufacturing of packaging substrates, the MSAP process is widely used because it can achieve the production of high-density and fine-pitch circuits. One of the key steps in the MSAP process is to form a fine circuit pattern on the substrate, and the exposure process is a commonly used patterning method. However, during the development process of the exposure process, due to the characteristics of the photosensitive film and the influence of process parameters, it is easy to form base feet (Footing) of the photosensitive film at the circuit edges, that is, photosensitive film residues. These residues will affect the accuracy of the subsequent electroplating process, resulting in problems such as rough circuit edges and uneven line widths, ultimately affecting the electrical performance and reliability of the packaging substrate.

[0003] Specifically, the existence of the photosensitive film base feet will cause the following problems: Uneven electroplating: The base foot area will hinder the uniform distribution of the electroplating solution, resulting in inconsistent electroplating layer thickness. Rough circuit edges: The base foot residues will make the circuit edges uneven, affecting the stability of signal transmission.

[0004] Difficult line width control: The base feet will cause a large deviation between the actual line width and the design value, affecting the accuracy of high-density circuits.

[0005] Currently, the commonly used methods for removing the photosensitive film base feet in the industry mainly include the following: Chemical cleaning method: The substrate is cleaned by using strong acid or strong alkali solutions to remove the residual photoresist. However, this method is easy to corrode the substrate surface and has poor applicability to fine circuits.

[0006] Mechanical polishing method: The base feet are removed by physical grinding, but this method is easy to damage the circuits and is not applicable to high-density circuits.

[0007] Ozone treatment method: The strong oxidizing property of ozone is used to decompose the photoresist residues, but the efficiency of ozone treatment is low, and the effect on certain types of photoresist is limited.

[0008] Ultraviolet light treatment method: The photoresist residues are photodegraded by ultraviolet light irradiation, but this method requires a long treatment time and has poor effect on removing deep base feet.

[0009] Although the above methods can remove the photosensitive film base feet to a certain extent, there are still the following deficiencies: Insufficient accuracy: Existing methods are difficult to completely remove the base feet at the edges of fine circuits, affecting the accuracy and consistency of the circuits.

[0010] High process complexity: Some methods require complex equipment or process conditions, increasing production costs and process difficulties.

[0011] Risk of substrate damage: Methods such as chemical cleaning and mechanical polishing are likely to damage the substrate surface, affecting the reliability of the product.

[0012] Low efficiency: Some methods (such as ozone treatment and ultraviolet treatment) require a long processing time, reducing production efficiency. For example, Chinese Patent Publication No. CN116647996A discloses a method for integrally removing a photosensitive dry film and a solder layer on a copper-clad ceramic substrate, which uses a chemical cleaning method. This method includes the following steps: S1. Developing the copper-clad ceramic substrate that has completed the film laminating and exposure processes; S2. Performing copper etching on the developed copper-clad ceramic substrate; S3. Placing the copper-etched copper-clad ceramic substrate into a configured quantitative integrated chemical solution system for film removal, and after film removal, configuring a quantitative integrated chemical solution system for solder etching treatment. It simplifies the chemical solution system, uses the same chemical solution for film removal and solder etching, saves costs, and saves time, manpower, and material resources. Moreover, the wastewater recycling treatment is relatively simplified, and there is no obvious pungent odor, ensuring the health of employees. In terms of solder etching, compared with the traditional EDTA and ammonia water systems, its chemical solution is more durable and the etching is cleaner, with less etching of the sidewalls of the trench copper. It is suitable for all AMB process copper-clad ceramic substrates and can etch different types of solders. However, it removes the solder at the bottom of the dry film rather than the dry film base feet, and still has the aforementioned problems. Summary of the Invention

[0013] The main objective of the present invention is to overcome some defects in the prior art and provide a method for removing the base feet of a photosensitive film based on plasma treatment to solve problems such as rough circuit edges and uneven line widths existing in the prior art.

[0014] A method for removing the base feet of a photosensitive film based on plasma treatment according to the present invention includes: Plasma treatment: Performing plasma treatment on the developed glass substrate to remove the base feet of the photosensitive film at the circuit edges; Pattern electroplating: Performing pattern electroplating on the glass substrate after plasma treatment to form metal circuits; Film stripping: Removing the excess photosensitive film on the electroplated glass substrate; Etching: Etching the base copper at the bottom to form refined circuits.

[0015] Due to its characteristics such as high efficiency, environmental protection, and non-contact, plasma processing technology is applied to the removal of the base of the photosensitive film. By using an inductively coupled plasma (ICP) device to excite it into plasma, it can effectively remove the residue of the photosensitive film through the dual effects of physical bombardment and chemical reaction, and at the same time will not damage the surface of the substrate, so as to solve the problems such as rough circuit edges and uneven line widths existing in the prior art. This method has the advantages of simple process, high efficiency, wide applicability, etc., and can improve the quality and consistency of fine circuits when using the MSAP process on glass substrates.

[0016] Preferably, the gas used for the plasma treatment is O 2 and Ar, The total gas flow rate for the plasma treatment is 1200 - 1800 sccm, The gas flow rate ratio for the plasma treatment is O 2 :Ar = 1:2, The power of the plasma treatment is 2500 - 2700 watt, The time of the plasma treatment is 28 - 32 Sec, The vacuum degree of the plasma treatment is 200 - 240 mtorr.

[0017] By optimizing the gas composition, gas ratio, gas flow rate, power parameters, and treatment time of the plasma treatment, the base at the circuit edge can be removed efficiently and precisely, while avoiding damage to the substrate surface and the circuit.

[0018] Preferably, for the pattern electroplating, a copper sulfate and sulfuric acid system solution is used in combination with a JUC electroplating additive to perform pattern electroplating on the glass substrate after the plasma treatment.

[0019] Preferably, for the stripping, an organic stripping solution is used to remove the excess photosensitive film on the glass substrate after electroplating.

[0020] Preferably, for the etching, a sulfuric acid and hydrogen peroxide system solution is used to etch the underlying copper.

[0021] Preferably, the developed glass substrate is obtained through the following method: Anti-reflective coating: Stick an anti-reflective coating on the pre-treated substrate; Exposure: Expose the glass substrate to cause a photochemical reaction in the photosensitive film; Development: Use a developer to develop the exposed glass substrate to remove the photosensitive film in the unexposed area and form a circuit pattern.

[0022] Preferably, the anti-reflective coating is obtained by cleaning and surface-treating the glass substrate to obtain a pre-treated substrate. Preferably, the exposure is performed on the glass substrate using a UV - direct writing automatic exposure machine.

[0023] Preferably, the development is performed on the exposed glass substrate using a developer.

[0024] Compared with the prior art, the present invention has the following beneficial effects: A method for removing the base pins of a photosensitive film based on plasma treatment according to the present invention, through the plasma treatment technology, uses a mixed gas of O 2 and Ar to be excited into plasma through an inductively coupled plasma (ICP) device. Through the dual effects of physical bombardment and chemical reaction, the residual photosensitive film is effectively removed, and at the same time, the surface of the substrate will not be damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a residual effect diagram of the first part of the dry film pins at the bottom of the photosensitive film before plasma treatment after development of the present invention; Figure 2 It is a residual effect diagram of the second part of the dry film pins at the bottom of the photosensitive film before plasma treatment after development of the present invention; Figure 3 It is a residual effect diagram of the third part of the dry film pins at the bottom of the photosensitive film before plasma treatment after development of the present invention; Figure 4 It is an effect diagram of removing the base pins of the first part of the photosensitive film after plasma treatment of the present invention; Figure 5 It is an effect diagram of removing the base pins of the second part of the photosensitive film after plasma treatment of the present invention; Figure 6 It is an effect diagram of removing the base pins of the third part of the photosensitive film after plasma treatment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0027] The present invention discloses a method for removing the base pins of a photosensitive film based on plasma treatment, including the following steps: 1: Anti - coating The glass substrate is cleaned and surface - treated, and an anti - coating film is pasted on the pretreated substrate.

[0028] 2: Exposure The glass substrate is exposed using a UV - direct writing automatic exposure machine to cause a photochemical reaction of the photosensitive film.

[0029] 3: Development The exposed glass substrate is developed using a developer to remove the photosensitive film in the unexposed area and form a circuit pattern. The residual dry film pins at the bottom of the processed photosensitive film are asFigures 1 - 3 as shown

[0030] 4: Plasma treatment Perform plasma treatment on the developed glass substrate to remove the photosensitive film base feet at the circuit edges.

[0031] The gases used for plasma treatment are O 2 and Ar, The total gas flow rate for plasma treatment is 1200 - 1800 sccm, The gas flow rate ratio for plasma treatment is O 2 :Ar = 1:2, The power for plasma treatment is 2500 - 2700 watt, The time for plasma treatment is 28 - 32 Sec, The vacuum degree for plasma treatment is 200 - 240 mtorr.

[0032] By optimizing the gas composition, gas ratio, gas flow rate, power parameters, and treatment time of plasma treatment, the base feet at the circuit edges can be removed efficiently and precisely, while avoiding damage to the substrate surface and circuits.

[0033] 5: Pattern electroplating Use a copper sulfate and sulfuric acid system solution in combination with the electroplating additives VL - A; VL - B; VL - CS of JUC to perform pattern electroplating on the glass substrate after plasma treatment to form metallized circuits.

[0034] 6: Film stripping Use the Yino organic film stripping solution ST - A; ST - B to remove the excess photosensitive film on the glass substrate after electroplating.

[0035] 7: Etching Use the sulfuric acid hydrogen peroxide system solution CPE - 770D of Linghe Chemical Industry to etch the bottom base copper to finally form refined circuits. The final treatment effect is as Figures 4 - 6 shown

[0036] It solves the problems of rough circuit edges and uneven line widths existing in the prior art; has the advantages of simple process, high efficiency, wide applicability, etc., and can improve the quality and consistency of refined circuits when using the MSAP process on glass substrates.

[0037] Especially compared with the patents in the background art, by removing the base foot residues at the bottom of the dry film after development through plasma treatment, the problems of rough circuit edges and uneven line widths existing in the prior art are solved.

[0038] Example 1 This embodiment discloses a method for removing the base pins of a photosensitive film based on plasma treatment, comprising the following steps: 1: Anti-coating Clean and surface-treat the glass substrate, and attach an anti-coating to the pretreated substrate.

[0039] 2: Exposure Use a UV - direct writing automatic exposure machine to expose the glass substrate, causing a photochemical reaction in the photosensitive film.

[0040] 3: Development Use a developer to develop the exposed glass substrate, removing the photosensitive film in the unexposed areas to form a circuit pattern. The residual dry film pins at the bottom of the treated photosensitive film are as Figure 1 shown.

[0041] 4: Plasma treatment Perform plasma treatment on the developed glass substrate to remove the base pins of the photosensitive film at the circuit edges.

[0042] The gases used for plasma treatment are O 2 and Ar, The total gas flow rate for plasma treatment is 1500 sccm, The gas flow rate ratio for plasma treatment is O 2 :Ar = 1:2, The power of plasma treatment is 2600 watt, The time of plasma treatment is 30 Sec, The vacuum degree of plasma treatment is 220 mtorr.

[0043] Due to its characteristics such as high efficiency, environmental protection, and non-contact, plasma treatment technology uses a mixed gas of O 2 and Ar to be excited into plasma through an inductively coupled plasma (ICP) device. It can effectively remove the photosensitive film residues through the dual effects of physical bombardment and chemical reaction, and will not cause damage to the substrate surface at the same time.

[0044] 5: Pattern electroplating Use a copper sulfate and sulfuric acid system solution in combination with a JUC electroplating additive to perform pattern electroplating on the glass substrate after plasma treatment to form metal circuits.

[0045] 6: Film stripping Use a Yino organic film stripping solution to remove the excess photosensitive film on the glass substrate after electroplating.

[0046] 7: Etching Use a sulfuric acid and hydrogen peroxide system solution from Linghe Chemical Industry to etch the bottom base copper to finally form a refined circuit. The final treatment effect is asFigures 4 - 6 as shown

[0047] Example 2 Differing from Example 1 is that the total gas flow rate for plasma treatment is 1200 sccm, the gas flow rate ratio for plasma treatment O 2 :Ar = 1:2, the power of plasma treatment is 2500 watt, the time of plasma treatment is 28 Sec, the vacuum degree of plasma treatment is 200 mtorr.

[0048] Example 3 Differing from Example 1 is that the total gas flow rate for plasma treatment is 1400 sccm, the gas flow rate ratio for plasma treatment O 2 :Ar = 1:2, the power of plasma treatment is 2500 watt, the time of plasma treatment is 28 Sec, the vacuum degree of plasma treatment is 200 mtorr.

[0049] Example 4 Differing from Example 1 is that the total gas flow rate for plasma treatment is 1800 sccm, the gas flow rate ratio for plasma treatment O 2 :Ar = 1:2, the power of plasma treatment is 2550 watt, the time of plasma treatment is 29 Sec, the vacuum degree of plasma treatment is 210 mtorr.

[0050] Example 5 Differing from Example 1 is that the total gas flow rate for plasma treatment is 1600 sccm, the gas flow rate ratio for plasma treatment O 2 :Ar = 1:2, the power of plasma treatment is 2650 watt, the time of plasma treatment is 31 Sec, the vacuum degree of plasma treatment is 230 mtorr.

[0051] Example 6 Differing from Example 1 is that The total gas flow rate for plasma treatment is 1700 sccm, The gas flow rate ratio for plasma treatment O 2 : Ar = 1:2, The power of plasma treatment is 2700 watt, The time of plasma treatment is 32 Sec, The vacuum degree of plasma treatment is 240 mtorr.

[0052] The variations of plasma treatment parameters and their corresponding technical effects in different embodiments are as follows in the table:

[0053] In summary, the key parameters and their technical effects of different embodiments are as follows: Increasing the flow rate (such as in Embodiments 4 - 6) can enhance the plasma density and improve the removal effect, but may increase the gas consumption cost.

[0054] When the flow rate is relatively low (such as in Embodiments 2 - 3), the removal effect is slightly weaker, but the processing time is shorter, which is suitable for scenarios with high efficiency requirements.

[0055] Treatment with high power (such as in Embodiments 5 - 6) and long time (such as in Embodiment 6) can significantly improve the removal effect of the pedestal, but may lead to an increase in energy consumption.

[0056] Treatment with low power (such as in Embodiments 2 - 3) and short time (such as in Embodiments 2 - 3) has higher efficiency, but the effect may be slightly insufficient.

[0057] Increasing the vacuum degree (such as in Embodiments 5 - 6) helps the uniform distribution of the plasma and improves the processing consistency, but may require higher equipment requirements.

[0058] Embodiment 1 performs excellently in terms of parameter balance and is suitable for most scenarios.

[0059] Embodiment 6 has the best removal effect, but the cost and time need to be weighed.

[0060] Embodiments 2 - 3 are applicable to scenarios with high efficiency requirements or cost sensitivity.

[0061] Comparison with the prior art: Advantages: By optimizing the plasma parameters, problems such as rough line edges and uneven line widths are significantly improved, and the quality and consistency of the fine lines are enhanced.

[0062] Applicability: Applicable to the MSAP process for glass substrates, with advantages such as simple process, high efficiency, and wide applicability.

[0063] Certainly, the above content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples either. Equivalent changes and improvements made by those of ordinary skill in the art within the essence of the present invention shall fall within the scope covered by the patent of the present invention.

Claims

1. A method for removing the footing of a photosensitive film based on plasma treatment, characterized in that: include: Plasma treatment: Plasma treatment is performed on the developed glass substrate to remove the photosensitive film footing at the edge of the circuit; Pattern electroplating: Pattern electroplating is performed on the glass substrate after plasma treatment to form metal circuits; Stripping: removing the excess photosensitive film on the glass substrate after electroplating; Etching: Etch the bottom copper to form fine circuits.

2. A method for removing a photosensitive film footing based on plasma treatment according to claim 1, characterized in that: The plasma treatment uses gases O2 and Ar, The total gas flow rate of plasma treatment is 1200-1800 sccm, The gas flow ratio of plasma treatment is O2:Ar=1:2, Plasma treatment power 2500-2700 watt, Plasma treatment time 28-32 Sec, The vacuum degree of plasma treatment is 200-240 mtoor.

3. The method for removing the photosensitive film footing based on plasma treatment according to claim 1, characterized in that: The pattern electroplating uses copper sulfate and sulfuric acid system solution with JUC electroplating additives to perform pattern electroplating on the glass substrate after plasma treatment.

4. The method for removing the photosensitive film footing based on plasma treatment according to claim 1, characterized in that: The film stripping uses an organic film stripping solution to remove the redundant photosensitive film on the glass substrate after electroplating.

5. The method for removing the footing of a photosensitive film based on plasma treatment according to claim 1, characterized in that: The etching uses a sulfuric acid and hydrogen peroxide system solution to etch the bottom base copper.

6. The method for removing the photosensitive film footing based on plasma treatment according to claim 5, characterized in that: The developed glass substrate is obtained by the following method: Anti-plating: Apply anti-plating film on the pre-treated substrate; Exposure: Expose the glass substrate to cause a photochemical reaction in the photosensitive film; Development: Use developer to develop the exposed glass substrate to remove the photosensitive film in the unexposed area to form a circuit pattern.

7. The method for removing the photosensitive film footing based on plasma treatment according to claim 6, characterized in that: The anti-plating film is prepared by cleaning and surface treating a glass substrate to obtain a pre-treated substrate.

8. The method for removing the photosensitive film footing based on plasma treatment according to claim 7, characterized in that: The exposure uses a UV-direct-drawing automatic exposure machine to expose the glass substrate.

9. The method for removing the photosensitive film footing based on plasma treatment according to claim 7, characterized in that: The developing step involves developing the exposed glass substrate using a developer.

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