A method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation

Abstract

This invention discloses a method for preparing a double-sided patterned ceramic substrate for shielding or isolation, belonging to the field of integrated circuit manufacturing. The method includes the following steps: S1, forming a seed metal layer on a ceramic substrate; S2, applying photoresist to surface A1; S3, suspending and curing the ceramic substrate above a hot plate; S4, applying photoresist to surface B1; S5, suspending and curing the ceramic substrate above a hot plate to form a double-sided cured ceramic substrate; S6, double-sided exposure, baking, development, and metallization to form a double-sided patterned ceramic substrate; S7, removing the photoresist and then dry etching to obtain the double-sided patterned ceramic substrate for shielding or isolation. This invention increases the coverage of vias and sidewalls to 95%, eliminates white edges, and achieves clean development.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing, and more specifically, to a method for preparing a double-sided patterned ceramic substrate for shielding or isolation. Background Technology

[0002] Double-sided patterned ceramic substrates used for shielding or isolation are the core carriers of high-end electronic devices. With the excellent insulation and heat dissipation properties of ceramics, combined with double-sided circuit patterns, they can efficiently achieve electromagnetic shielding and signal isolation, suppress circuit interference, adapt to high-power and high-frequency scenarios, and significantly improve the stability and reliability of equipment operation.

[0003] Double-sided patterned ceramic substrates used for shielding or isolation have metallized patterns distributed on both the upper and lower surfaces of a ceramic substrate with through holes, while the inner walls of the through holes have no metallized layer.

[0004] The existing fabrication process for double-sided patterned ceramic substrates used for shielding or isolation is as follows: A ceramic substrate with distributed through-holes to be patterned is formed (where the upper surface is denoted as surface A and the lower surface as surface B). Surface A is coated with negative photoresist, and then placed on a hot plate for curing (surface A facing upwards, surface B in contact with the hot plate, curing on the hot plate, followed by exposure and PEB (post-expose) processing). (Bake, exposure followed by baking), development, forming the first metallization pattern on side A, removing the negative photoresist; coating the negative photoresist on side B, then placing it on a hot plate for curing (side B facing up, side A attached to the hot plate, curing on the hot plate, after curing, exposure, development, forming the first metallization pattern on side B, removing the negative photoresist; forming a double-sided patterned ceramic substrate for shielding or isolation; in the prior art, in order to improve the conductivity and adhesion of the metallization pattern, a seed metal (such as titanium, chromium, titanium-tungsten alloy, copper, gold or nickel, etc.) is usually covered on the ceramic substrate before patterning. In the seed metal covering process, after the metal patterning is completed, the seed metal also needs to be removed by etching.

[0005] The existing manufacturing process has the following shortcomings: (1) The method of only patterning the surface results in a long process flow, long production time, and high production cost. (2) The photoresist coverage on the sidewalls of the via is low after coating and curing, leading to a higher risk of subsequent metallization of the via.

[0006] The above background information is provided to facilitate understanding of the present invention and is not intended to be publicly known technology disclosed to the general public prior to the application of this invention. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for preparing a double-sided patterned ceramic substrate for shielding or isolation. This method increases the coverage of through holes and sidewalls to 95%, eliminates white edges, and ensures clean development.

[0008] A method for preparing a double-sided patterned ceramic substrate for shielding or isolation includes the following steps: S1, A seed metal layer is formed on the ceramic substrate with through holes to be patterned, which becomes the ceramic substrate. The upper surface of the ceramic substrate is denoted as surface A1 and the lower surface is denoted as surface B1. S2, apply photoresist to surface A1; S3, the ceramic substrate is suspended above the hot plate and cured, with A1 side on top and B1 side on the bottom. The curing temperature is 120℃~130℃ and the curing time is 2min~5min, forming a ceramic substrate with A1 side already cured. S4. Apply photoresist to B1 surface by spraying. S5, the ceramic substrate with the A1 side already cured is suspended above the hot plate for curing, with the A1 side at the bottom and the B1 side at the top. The curing temperature is 120℃~130℃ and the curing time is 2min~5min, forming a ceramic substrate with both sides cured. S6, double-sided exposure, baking, development and metallization to form a ceramic substrate with double-sided patterns; S7, Remove the photoresist, and then dry etch the ceramic substrate with double-sided patterns to remove the seed metal layer not covered by the patterns, to obtain a double-sided patterned ceramic substrate for shielding or isolation. In S3, the distance between surface B1 and the hot plate is denoted as h1. In S5, the distance between surface A1 and the hot plate is denoted as h2, where h1>0 and h2>0. The inner walls of the through-holes in the double-sided patterned ceramic substrate used for shielding or isolation are not covered with metal.

[0009] Optionally, in S1, the ceramic substrate is an aluminum nitride ceramic substrate or an alumina ceramic substrate.

[0010] Optionally, in S1, the seed metal layer is formed by sputtering, and the sputtered metal is TiPtAu.

[0011] Optionally, in S1, the target thickness of Ti in the seed metal layer is 2000 Å, the target thickness of Pt is 2000 Å, and the target thickness of Au is 1000 Å.

[0012] Optionally, in both S2 and S4, the coating method is spraying, and the target thickness is 7μm~8μm.

[0013] Optionally, in S2 and S4, the photoresist is a negative photoresist.

[0014] Optionally, in S3, 0.1mm <h<10mm。

[0015] Optionally, in S3 and S5, the curing temperature of S3 is greater than that of S5.

[0016] Optionally, the curing temperature of S3 is 130℃ and the curing time is 3 min; the curing temperature of S5 is 120℃ and the curing time is 3 min.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention improves the coverage of through holes and sidewalls by 20% to 80% through a process of applying adhesive to one side, baking, applying adhesive to the other side, baking, double-sided exposure, development, and electroplating.

[0018] The present invention also improves the coverage of through holes and sidewalls to 95% by setting different baking temperatures for the first and second sides, resulting in no white edges and clean development. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the ceramic substrate structure of the present invention; Figure 2 This is a schematic diagram of the curing pad structure of the present invention; Figure 3 yes Figure 2 Enlarged view at point C; Figure 4 This is a schematic diagram of the ceramic substrate structure with double-sided patterns according to the present invention; Figure 5 This is a schematic diagram of the double-sided patterned ceramic substrate structure used for shielding or isolation according to the present invention; Figure 6 This is a schematic diagram of the coverage state of the through hole and sidewall in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the coverage state of the through hole and sidewall in Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the coverage state of the through hole and sidewall in Comparative Example 1 of the present invention; Figure labeling: 1. Ceramic substrate, 2. Through hole, 3. Curing pad, 4. Substrate support, 5. Upper metallized pattern layer, 6. Lower metallized pattern layer, 7. Seed metal layer, 8. Negative photoresist layer not developed, 9. Square frame, 10. Spacer, 11. Cutout area. Detailed Implementation

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection via an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In the description of this invention, "a plurality of" means two or more, unless otherwise precisely specified.

[0023] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0026] Example 1 A method for preparing a double-sided patterned ceramic substrate for shielding or isolation includes the following steps: S1, take a ceramic substrate 1 with through holes 2 to be patterned (e.g., Figure 1 A seed metal layer is formed on a ceramic substrate 1 with distributed through holes (where the upper surface is denoted as surface A1 and the lower surface as surface B1), forming a ceramic substrate (where the upper surface of the ceramic substrate is denoted as surface A1 and the lower surface as surface B1). The seed metal layer is formed on surfaces A and B and the inner wall of the through holes 2. The seed metal layer can be formed by sputtering. In this embodiment, the seed metal layer is formed by sputtering, using TiPtAu as the sputtering metal. The target thickness of Ti in the seed metal layer is 2000 Å, the target thickness of Pt is 2000 Å, and the target thickness of Au is 1000 Å.

[0027] S2. A negative photoresist is applied to the A1 surface of the ceramic substrate by spraying. The can pressure is 0.25 MPa, the spraying pressure is 0.25 MPa, the number of spraying times is 3, the spraying temperature is 60℃, and the thickness of the photoresist layer is 7μm~8μm.

[0028] S3, Place the ceramic substrate with negative photoresist coated on surface A1 into... Figure 2 and Figure 3 The curing pad 3 is placed on the substrate support 4, and then the curing pad 3 is placed on the hot plate for curing at a curing temperature of 120°C. After curing, the ceramic substrate is removed (curing time is 3 minutes), forming a ceramic substrate with surface A1 cured. During curing, surface A1 is on top and surface B1 is on the bottom, and the distance between surface B1 and the hot plate is (0.1mm~2mm).

[0029] S4. Apply negative photoresist to the B1 side of the ceramic substrate that has been cured on the A1 side by spraying. Place a polishing ceramic pad on the back to prevent the photoresist from sticking. The can pressure is 0.25 MPa, the spray pressure is 0.25 MPa, the number of spraying times is 3, the spraying temperature is 60℃, and the thickness of the photoresist layer is 7μm~8μm.

[0030] S5, Place the ceramic substrate with negative photoresist coated on side B1 into Figure 2 The curing pad 3 is placed on the substrate support position 4, and then the curing pad 3 is placed on the hot plate for curing. The curing temperature is 120℃ (curing time is 3min). After curing, the ceramic substrate is removed to form a ceramic substrate cured on both sides. In the figure, A1 side is at the bottom and B1 side is at the top. The distance between A1 side and the hot plate is (0.1mm~2mm).

[0031] S6 exposes the ceramic substrate that has been cured on both sides to both sides.

[0032] S7, Place the double-sided exposed ceramic substrate on the curing pad 3, A1 side facing up, and bake after exposure at 120℃ for 2 minutes. After baking, cool to room temperature, then develop and metallize to form a substrate as shown in the image. Figure 4 A ceramic substrate with double-sided patterns. Figure 4 In the middle, the upper metallization pattern layer 5 is located above the A side of the ceramic substrate 1, and the lower metallization pattern layer 6 is located below the B side of the ceramic substrate 1. The upper metallization pattern layer 5 and the ceramic substrate 1 are seed metal layers 7, and the lower metallization pattern layer 6 and the ceramic substrate 1 are seed metal layers 7. The negative photoresist layer 8 that is not developed fills the inner wall of the via 2 and the area not covered by the metallization pattern.

[0033] S8, remove the photoresist, then dry etch the patterned ceramic substrate to remove the seed metal (the part not covered by the pattern), obtaining a patterned ceramic substrate with two sides for shielding or isolation, such as... Figure 5 As shown, Figure 5 middle, Figure 4 The negative photoresist layer 8 that was not developed and the seed metal layer 7 that was not covered by the metallization pattern have been removed by dry etching. An upper metallization pattern layer 5 and a lower metallization pattern layer 6 are covered on the ceramic substrate 1. The upper metallization pattern layer 5 is connected to the ceramic substrate 1 through the seed metal layer 7, and the lower metallization pattern layer 6 is connected to the ceramic substrate 1 through the seed metal layer 7. The inner wall of the via 2 is not covered by the metallization pattern.

[0034] In this embodiment, the curing pad 3 includes a square frame 9, and at least one partition 10 is provided inside the square frame 9. The partition 10 divides the square frame 9 into at least two or more hollow areas 11. Each hollow area 11 is used to place a ceramic substrate 1. The four corners of each hollow area 11 are substrate support positions 4. Each substrate support position 4 is connected to the square frame 9 and / or the partition 10.

[0035] Take the double-sided cured ceramic substrate formed by S5 and test the coverage status of through hole 2 and sidewalls. The results are as follows. Figure 6 And Table 1.

[0036] Example 2 The difference between this embodiment and embodiment 1 is that in this embodiment, the curing temperature in S3 is 130℃ and the curing time is 3min; in S5, the curing temperature is 130℃ and the curing time is 3min; and in S7, the curing temperature is 120℃ and the curing time is 3min.

[0037] Take the double-sided cured ceramic substrate formed by S5 and test the coverage status of through hole 2 and sidewalls. The results are as follows. Figure 7 And Table 1.

[0038] Comparative Example 1 This comparative example is a method for preparing a double-sided patterned ceramic substrate for shielding or isolation. Compared with the example, except that the curing pad 3 is not used, all other equipment used is the same, and the parameters of the other processes are also the same except for curing.

[0039] A method for preparing a double-sided patterned ceramic substrate for shielding or isolation includes the following steps: S1, a ceramic substrate 1 with through holes 2 to be patterned is taken, and a seed metal layer is formed on the ceramic substrate 1 with through holes to be patterned, becoming a ceramic substrate (wherein, the upper surface of the ceramic substrate is denoted as surface A1, and the lower surface is denoted as surface B1). The seed metal layer is formed on surface A, surface B, and the inner wall of the through holes 2. The seed metal layer can be formed by sputtering. In this embodiment, the seed metal layer is formed by sputtering, and the sputtered metal is TiPtAu. In the seed metal layer, the target thickness of Ti is 2000 Å, the target thickness of Pt is 2000 Å, and the target thickness of Au is 1000 Å.

[0040] S2. A negative photoresist is applied to the A1 surface of the ceramic substrate by spraying. The can pressure is 0.25 MPa, the spraying pressure is 0.25 MPa, the number of spraying times is 3, the spraying temperature is 60℃, and the thickness of the photoresist layer is 7μm~8μm.

[0041] S3. Place the ceramic substrate with negative photoresist coated on side A1 on a hot plate for curing. During curing, side A1 is on top and side B1 is on the bottom, with side B1 in contact with the hot plate. The curing temperature is 120℃ and the curing time is 2 minutes. After curing, remove the ceramic substrate to form a ceramic substrate with side A1 cured.

[0042] Single-sided exposure of the cured ceramic substrate on surfaces S4 and A1. S5, after exposure, is baked at 100℃ for 2 minutes, followed by development and metallization to form a ceramic substrate with an A1 surface pattern.

[0043] S6. Apply negative photoresist to the B1 side of the ceramic substrate with the pattern on the A1 side. The application method is spraying, with a can pressure of 0.25 MPa, a spraying pressure of 0.25 MPa, and 3 spraying times. The spraying temperature is 60℃, and the thickness of the photoresist layer is 7μm~8μm.

[0044] S7. Place the ceramic substrate with negative photoresist coated on side B1 and patterned side A1 on a hot plate for curing. During curing, side B1 is on top and side A1 is on the bottom. The curing temperature is 120℃ and the curing time is 2 minutes. After curing, remove the ceramic substrate to form a ceramic substrate with both sides cured.

[0045] S8 involves exposing, developing, and metallizing the ceramic substrate cured on both sides via B1, ultimately forming a structure like... Figure 4 A ceramic substrate with double-sided patterns. Figure 4 In the middle, the upper metallization pattern layer 5 is located above the A side of the ceramic substrate 1, and the lower metallization pattern layer 6 is located below the B side of the ceramic substrate 1. The upper metallization pattern layer 5 and the ceramic substrate 1 are seed metal layers 7, and the lower metallization pattern layer 6 and the ceramic substrate 1 are seed metal layers 7. The negative photoresist layer 8 that is not developed fills the inner wall of the via 2 and the area not covered by the metallization pattern.

[0046] S9, remove the photoresist, then dry etch the patterned ceramic substrate to remove the seed metal (the part not covered by the pattern), obtaining a patterned ceramic substrate on both sides for shielding or isolation, such as... Figure 5 As shown, Figure 5 middle, Figure 4 The negative photoresist layer 8 that was not developed and the seed metal layer 7 that was not covered by the metallization pattern have been removed by dry etching. An upper metallization pattern layer 5 and a lower metallization pattern layer 6 are covered on the ceramic substrate 1. The upper metallization pattern layer 5 is connected to the ceramic substrate 1 through the seed metal layer 7, and the lower metallization pattern layer 6 is connected to the ceramic substrate 1 through the seed metal layer 7. The inner wall of the via 2 is not covered by the metallization pattern.

[0047] Take the double-sided cured ceramic substrate formed by S7 and test the coverage status of through hole 2 and sidewalls. The results are as follows. Figure 8 And Table 1.

[0048] In Examples 1, 2, and Comparative Example 1, because there is a certain distance between the ceramic substrate and the hot plate in Examples 1 and 2, the difference in temperature between the white substrate placed on the gasket and the temperature measured by thermocouples was 10~15℃. Therefore, the baking temperature was higher than that in Comparative Example 1. The pre-baking and post-baking times directly affected the development effect. The curing temperature and time were adjusted based on the pattern after development. The coverage of the sidewalls and through holes after development was observed.

[0049] Table 1 Coverage Status Inspection Table for Through Holes and Sidewalls from Figures 6-7 As can be seen from Table 1, in Embodiment 1 of the present invention, by modifying the process, the coverage of through holes and sidewalls is increased by 20% by using single-sided coating, baking, then coating on the other side, baking, double-sided exposure, development, and electroplating. Embodiment 2 is the same as Embodiment 1, but by differentiating the baking temperatures of the first and second sides, the coverage of through holes and sidewalls is increased to 95%, with no white edges and clean development.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for the preparation of a double-sided tape patterned ceramic substrate for shielding or isolation, characterized by, Includes the following steps: S1, A seed metal layer is formed on the ceramic substrate with through holes to be patterned, which becomes the ceramic substrate. The upper surface of the ceramic substrate is denoted as surface A1 and the lower surface is denoted as surface B1. S2, apply photoresist to surface A1; S3, the ceramic substrate is suspended above the hot plate and cured, with A1 side on top and B1 side on the bottom. The curing temperature is 120℃~130℃ and the curing time is 2min~5min, forming a ceramic substrate with A1 side already cured. S4. Apply photoresist to B1 surface by spraying. S5, the ceramic substrate with the A1 side already cured is suspended above the hot plate for curing, with the A1 side at the bottom and the B1 side at the top. The curing temperature is 120℃~130℃ and the curing time is 2min~5min, forming a ceramic substrate with both sides cured. S6, double-sided exposure, baking, development and metallization to form a ceramic substrate with double-sided patterns; S7, Remove the photoresist, and then dry etch the ceramic substrate with double-sided patterns to remove the seed metal layer not covered by the patterns, to obtain a double-sided patterned ceramic substrate for shielding or isolation. In S3, the distance between surface B1 and the hot plate is denoted as h1. In S5, the distance between surface A1 and the hot plate is denoted as h2, where h1>0 and h2>0. The inner walls of the through-holes in the double-sided patterned ceramic substrate used for shielding or isolation are not covered with metal.

2. The method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation according to claim 1, characterized in that, In S1, the ceramic substrate is either an aluminum nitride ceramic substrate or an alumina ceramic substrate.

3. The method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation according to claim 1, characterized in that, In S1, the seed metal layer is formed by sputtering, and the sputtered metal is TiPtAu.

4. The method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation according to claim 2, characterized in that, In S1, the target thickness of Ti in the seed metal layer is 2000 Å, the target thickness of Pt is 2000 Å, and the target thickness of Au is 1000 Å.

5. The method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation according to claim 1, characterized in that, In both S2 and S4, the coating method is spraying, and the target thickness is 7μm~8μm.

6. The method for preparing a double-sided tape patterned ceramic substrate for shielding or isolation according to claim 1, characterized in that, In S2 and S4, the photoresist is a negative photoresist.

7. The method for preparing a double-sided patterned ceramic substrate for shielding or isolation according to claim 1, characterized in that, 0.1mm <h1<10mm,0.1mm<h2<10mm。 8. The method for preparing a double-sided patterned ceramic substrate for shielding or isolation according to any one of claims 1-7, characterized in that, Of S3 and S5, the curing temperature of S3 is greater than that of S5.

9. The method for preparing a double-sided patterned ceramic substrate for shielding or isolation according to claim 8, characterized in that, The curing temperature of S3 is 130℃ and the curing time is 3 minutes; the curing temperature of S5 is 120℃ and the curing time is 3 minutes.

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