Insulating film composition for ceramic heater silicon carbide substrate

Abstract

The present invention relates to an insulating film composition for a ceramic heater silicon carbide substrate and, more specifically, comprises: a first agent comprising 30-50 wt% of glass frit, 20-40 wt% of aluminum oxide, 1-5 wt% of ethyl cellulose and 20-30 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate; and a second agent comprising 20-50 wt% of glass frit, 8-15 wt% of ethyl cellulose, 0.5-2 wt% of aluminum oxide, 40-65 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate and 0.1-1 wt% of dimethyl phthalate. A wafer-sized SiC substrate having a thickness of 2t or less, excellent insulating properties and minimized warpage can be manufactured using the insulating film composition for a ceramic heater silicon carbide substrate, of the present invention, and can be applied to a thick-film heater, and thus can maximize the productivity of a product produced using the heater.

Description

Insulating film composition of silicon carbide substrate for ceramic heater

[0001] The present invention relates to an insulating film composition for a silicon carbide substrate for a ceramic heater, and more particularly, to an insulating film composition for a silicon carbide substrate for a ceramic heater, which comprises a first agent and a second agent of different compositions, thereby enhancing the insulating properties of the insulating film composition while having a coefficient of thermal expansion (CTE) close to that of silicon carbide.

[0002] A ceramic heater for semiconductors generally comprises a ceramic substrate, a heating circuit formed on the ceramic substrate, and an insulating film formed on the ceramic substrate on which the heating circuit is formed. In addition, a thin film resistance temperature sensor (RTD sensor) is connected to a portion of the substrate where the heating circuit is not formed, and a number of terminals are also connected to the heating circuit.

[0003] The substrates of these ceramic heaters are made of conventional semiconductor materials such as silicon carbide and non-conductive materials such as aluminum nitride (AIN).

[0004] Among these, silicon carbide, a semiconductor material, possesses the high mechanical properties and thermal conductivity of ceramics. Furthermore, due to its inherent characteristics, it exhibits semiconductor properties, allowing current to flow when heated. Therefore, to be used as a heater substrate, an insulating film with excellent insulating properties must be formed on the substrate surface to prevent current flow even when heated.

[0005] Meanwhile, in order to increase the productivity of the product produced by the heater, the heater repeatedly raises and lowers the temperature. In order to resolve the latent heat of the heater, the thinner the substrate, the better the function. However, in the case of heaters manufactured by printing techniques, there is a problem that the substrate itself warps due to the difference in thermal expansion coefficient between the insulating film and the thin substrate (2t or less) during the high-temperature firing process, making it unusable as a substrate for heaters that prioritize flatness.

[0006] Therefore, due to problems such as warpage and insulation properties, substrates made of aluminum nitride materials of 4 tons or more have been mainly used in the past. That is, since heaters based on ceramic substrates made of semiconductor materials of wafer size and 2 tons or less have not existed in the past, there has not been a great need for an insulating film composition that minimizes insulation and warpage.

[0007] However, in recent years, in order to secure the competitiveness of ceramic heaters, there has been a demand for maximizing productivity and function as a heater, and the need for a semiconductor material substrate with a wafer size and a thickness of 2 tons or less has arisen.

[0008] Meanwhile, in Korean Patent No. 10-1598014, a method was proposed to suppress the occurrence of cracks and warping by dispersing the stress acting on the substrate by limiting the shape of the heating element.

[0009] In addition, Korean Patent Publication No. 10-2023-0015216 proposes a ceramic heater having an insulating layer including a glass matrix and thermally conductive particles.

[0010] However, all of these prior literatures were for application to general AIN substrates and substrates of 4t or more, and had the disadvantage of being difficult to apply to SiC substrates of 2t or less.

[0011] Accordingly, the purpose of the present invention is to provide an insulating film composition for a silicon carbide substrate for a ceramic heater, which is composed of first and second agents of different compositions, and which has high insulating properties while having a coefficient of thermal expansion (CTE) close to that of silicon carbide, thereby preventing warping during the firing process and enabling a thin SiC substrate having a thickness of 2 t or less to be used in a ceramic heater.

[0012] The insulating film composition of the silicon carbide substrate for a ceramic heater of the present invention for achieving the above-mentioned purpose comprises: a first agent including 30 to 50 wt% of glass frit, 20 to 40 wt% of aluminum oxide, 1 to 5 wt% of ethyl cellulose, and 20 to 30 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate; It is characterized by comprising a second agent comprising 20 to 50 wt% of glass frit, 8 to 15 wt% of ethyl cellulose, 0.5 to 2 wt% of aluminum oxide, 40 to 65 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, and 0.1 to 1 wt% of dimethyl phthalate.

[0013] The above first and second agents are characterized in that they are mixed and used in a weight ratio of 1:0.9 to 1.1.

[0014] The coefficient of thermal expansion (CTE) of the insulating film composition in which the first and second agents are mixed is 3.85×10 -6 / ℃~3.90×10 -6 It is characterized by / ℃.

[0015] The first and second agents are mixed and used in a weight ratio of 1:1, and the coefficient of thermal expansion (CTE) of the composition in which the first and second agents are mixed is 3.90×10 -6 / ℃, and when an insulating film is formed with a thickness of 60㎛ on a 12-inch or 8-inch wafer size, 2t thick SiC substrate by printing, the flatness of the substrate is characterized by being 30 to 40㎛ after firing at 800 to 1000℃ for 60 minutes.

[0016] According to the insulating film composition of the silicon carbide substrate for the ceramic heater of the present invention, a SiC substrate having excellent insulating properties and minimized warpage and having a thickness of 2t or less and a wafer size can be manufactured, and this can be applied to a thick-film heater, thereby having the advantage of maximizing the productivity of products produced by the heater.

[0017] Figure 1 is a schematic diagram showing a case where an insulating film is formed and cured on a SiC substrate having a thickness of 2t or less.

[0018] Hereinafter, the present invention will be described in detail.

[0019] The present invention is characterized by preventing warping due to shrinkage of an insulating film while further improving its insulating properties, by mixing heterogeneous materials having different values ​​of thermal expansion coefficients to form an insulating film having excellent insulating properties while having a thermal expansion coefficient close to that of SiC, thereby enabling a SiC substrate having a thickness of 2t or less to be used in a ceramic heater without warping during the curing and firing processes.

[0020] The insulating film composition of the present invention comprises a first agent comprising 30 to 50 wt% of glass frit, 20 to 40 wt% of aluminum oxide, 1 to 5 wt% of ethyl cellulose, and 20 to 30 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate; It is characterized by comprising a second agent comprising 20 to 50 wt% of glass frit, 8 to 15 wt% of ethyl cellulose, 0.5 to 2 wt% of aluminum oxide, 40 to 65 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, and 0.1 to 1 wt% of dimethyl phthalate.

[0021] The reason for configuring the first and second compositions in the present invention is that the main component that plays a bonding role is used in the first and second compositions in the same manner, but the composition ratio and the content of the filler responsible for thermal expansion are adjusted so that when the first and second compositions are mixed, the thermal expansion coefficient is close to that of SiC, thereby minimizing warpage even when applied to a thin substrate by printing.

[0022] First, let me explain the first clause in detail.

[0023] The above first agent contains 30 to 50 wt% of glass frit, 20 to 40 wt% of aluminum oxide, 1 to 5 wt% of ethyl cellulose, and 20 to 30 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, and is a composition for significantly improving insulating properties while minimizing warping.

[0024] First, glass frit is used as a bonding material. It is preferable that the glass frit be included in the first agent at 30 to 50 wt%. If the content is less than 30 wt%, sufficient bonding strength cannot be achieved, and filler materials cannot sufficiently dissolve into the glass frit. If the content exceeds 50 wt%, the amount becomes excessive, resulting in a relative lack of fillers, etc., and thus insufficient insulation cannot be secured.

[0025] The above aluminum oxide, as a filler, has excellent insulating properties and improves the insulating properties of the composition. However, since the degree of warpage is large and causes warpage when printed on a counterpart material and fired, its composition is very important. Therefore, in the present invention, it is preferable that the first agent contains 20 to 40 wt% of the above aluminum oxide. If the content is less than 20 wt%, it is difficult to secure sufficient insulating properties, and if it exceeds 40 wt%, it causes warpage during firing, cracks form, and cannot function as an insulating film when current is applied, and it becomes vulnerable to the physical environment.

[0026] The above ethyl cellulose acts as a thickener and is used to optimize viscosity for printing. The ethyl cellulose is preferably included in the first agent at 1 to 5 wt%, which is a composition ratio for optimizing viscosity.

[0027] The above 3-hydroxy-2, 2, 4-trimethylpentyl isobutyrate is mainly used when making synthetic materials such as flexible nanocomposite coating materials, and in the present invention, it plays the role of a lubricant and smoothens mixing as a mixing material. This is not only for mixing the bonding agent and filler in the first agent, but also plays a role in minimizing the occurrence of warpage by securing sufficient insulation with only a minimum amount of filler. It is preferable that the above 3-hydroxy-2, 2, 4-trimethylpentyl isobutyrate is included in the first agent at 20 to 30 wt%. If the content is less than 20 wt%, the bonding agent and filler are not sufficiently mixed, so the insulating film does not have the required properties. On the other hand, if it exceeds 30 wt%, it becomes an excess, which causes problems such as relatively lowered bonding strength and insulation.

[0028] In addition, the first agent may further include other additives such as a plasticizer in a composition of 0.1 to 1 wt%, and it is obvious that this is not limited.

[0029] The first agent as described above is a composition that not only secures sufficient insulation but also minimizes warping during firing due to aluminum oxide.

[0030] And the second agent of the present invention comprises 20 to 50 wt% of glass frit, 8 to 15 wt% of ethyl cellulose, 0.5 to 2 wt% of aluminum oxide, 40 to 65 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, and 0.1 to 1 wt% of dimethyl phthalate, and is mixed with the first agent to make the coefficient of thermal expansion (CTE) of the entire composition close to that of SiC, thereby minimizing warping during firing.

[0031] The above glass frit is used as a bonding material as in the first agent, and is preferably included in the second agent at 20 to 50 wt%. If the content is less than 20 wt%, sufficient bonding strength cannot be achieved, and filler materials cannot sufficiently dissolve into the glass frit. If the content exceeds 50 wt%, it becomes excessive, making it difficult to secure sufficient physical properties.

[0032] In addition, the ethyl cellulose is used as a thickener in the second agent to control viscosity at 8 to 15 wt%, and aluminum oxide is used as a filler at 0.5 to 2 wt%. Since the insulating film composition of the present invention is formulated so that the first agent has sufficient insulating properties, the second agent uses a minimum amount of the aluminum oxide.

[0033] The above 3-hydroxy-2, 2, 4-trimethylpentyl isobutyrate acts as a lubricant and is included in the second agent at 40 to 65 wt%. At this time, if the content is less than 40 wt%, sufficient mixing is difficult, and if it exceeds 65 wt%, bonding strength is reduced.

[0034] In addition, the above dimethyl phthalate is a material that does not react with water but reacts with resin, and is used as a solvent. It is preferable to include it in the second agent at 0.1 to 1 wt%. This is because if the content is too low, its role as a solvent is minimal, and even if it is excessive, it does not have any further enhanced effect, making it uneconomical.

[0035] In addition, the second agent may further include other additives such as a plasticizer in a composition of 0.1 to 1 wt%, and it is obvious that this is not limited.

[0036] The second agent as described above is a composition for controlling the coefficient of thermal expansion through smooth mixing with the first agent to have a value close to that of SiC.

[0037] That is, the present invention maximizes insulation and minimizes warpage by mixing and using the first and second agents configured as described above in a weight ratio of 1:0.9 to 1.1, thereby enabling a SiC material having a wafer size and thickness of 2t or less to be used as a heater substrate.

[0038] The reason why the first and second agents are mixed and used in the present invention at a weight ratio of 1:0.9 to 1.1, most preferably 1:1, is to derive an intermediate value of the CTE values ​​of the first and second agents to obtain the CTE value of SiC (4.0 to 4.5 × 10 -6 / ℃) with a CTE value of 3.85×10 -6 / ℃~3.90×10 -6 / ℃ is to be achieved.

[0039] That is, as shown in Fig. 1, when an insulating film (typical insulating film thickness of 60 ㎛) is formed and cured on a SiC substrate having a thickness of 2 t or less, if the CTE value of the insulating film is smaller or larger than that of SiC, the two ends of the substrate bend up or down, resulting in poor flatness, making it difficult to apply the insulating film as a substrate for a ceramic heater. The present invention solves this problem by using an insulating film composition having a CTE value close to that of a SiC substrate.

[0040] Hereinafter, the present invention will be described in detail through the attached examples.

[0041] (Example 1)

[0042] A first agent was prepared containing 40 wt% of glass frit (Cas No. 65997-18-4), 30 wt% of aluminum oxide (Al2O3), 3 wt% of ethyl cellulose (Cas No. 9004-57-3), and 27 wt% of 3-hydroxy-2, 2, 4-trimethylpentyl isobutyrate (Cas No. 77-68-9).

[0043] A second agent was prepared containing 40 wt% of glass frit (Cas No. 65997-18-4), 10 wt% of ethyl cellulose (Cas No. 9004-57-3), 1.5 wt% of aluminum oxide (Al2O3), 48 wt% of 3-hydroxy-2, 2, 4-trimethylpentyl isobutyrate (Cas No. 77-68-9), and 0.5 wt% of dimethyl phthalate (Cas No. 131-11-3).

[0044] And the first and second agents were mixed in a weight ratio of 1:1.

[0045] (Example 1)

[0046] The thermal expansion coefficient of Example 1 was measured and the results are shown in Table 1 below along with the thermal expansion coefficient of SiC.

[0047] Test Example 1 Result Classification Example 1 SiCCTE3.90×10 -6 / ℃4.0~4.5×10 -6 / ℃

[0048] As shown in Table 1 above, it was confirmed that Example 1 of the present invention had a CTE value close to the CTE value of SiC.

[0049] (Example 2)

[0050] A SiC substrate with a wafer size of 8 inches or 12 inches and a thickness of 2 t was prepared, and the composition of Example 1 was printed with a thickness of 60 μm to form an insulating film.

[0051] Then, after drying at 200°C for 10 hours, it was fired at 800-1000°C for 60 minutes. During the firing, the temperature was gradually increased and maintained at the highest temperature of 800-1000°C for 60 minutes. Next, after sufficiently cooling to room temperature, the flatness of the fired substrate was measured, and the results are shown in Table 2 below.

[0052] At this time, as comparative example 1, an insulating film made of a conventional general epoxy resin material was used on the same substrate as in example 1.

[0053] Test Example 2 Results Flatness (㎛) Flatness of SiC substrate after firing (control) 20~30 Comparative example after firing 170~80 Example 1 after firing (8 inches) 30~40 Example 1 after firing (12 inches) 30~40

[0054] As shown in Table 2 above, it was confirmed that Example 1 of the present invention had significantly improved flatness compared to Comparative Example 1 to which a conventional insulating film was applied, and it was confirmed that there was no significant warping compared to the SiC substrate even after firing.

[0055] (Example 3)

[0056] The composition of Example 1 and a 12-inch wafer size, 2-t thick SiC substrate were prepared, and a substrate for a ceramic heater was manufactured using a conventional method. At this time, an insulating film was formed with a thickness of 60 μm and fired using the same method as in Test Example 2.

[0057] And the withstand voltage was measured during insulation, and the results are shown in Table 3 below.

[0058] Test Example 3 Results Applied voltage (kV) Duration time (sec.) Leakage current (mA) Judgment 1.260 0.33 Pass 1.560 0.59 Pass Commercial heater withstand voltage spec.: 1.0kV 60sec., leakage current 10mA or less

[0059] As shown in Table 3 above, it was confirmed that the present invention satisfies the withstand voltage standards of 1.2 kV 60 sec. and 1.5 kV 60 sec.

[0060] Therefore, through the above-described test examples, it was confirmed that the insulating film composition of the present invention not only satisfies the withstand voltage standard of a general ceramic heater, but also enables application of a SiC substrate having a thickness of 2t or less and a wafer size to the heater.

[0061] While the present invention has been described in more detail above with reference to examples, the present invention is not necessarily limited to these examples, and various modifications may be made without departing from the technical spirit of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not stabilized by these examples. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included within the scope of the rights of the present invention.

Claims

1. A first agent comprising 30 to 50 wt% of glass frit, 20 to 40 wt% of aluminum oxide, 1 to 5 wt% of ethyl cellulose, and 20 to 30 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate; An insulating film composition for a silicon carbide substrate for a ceramic heater, characterized in that it comprises a second agent comprising 20 to 50 wt% of glass frit, 8 to 15 wt% of ethyl cellulose, 0.5 to 2 wt% of aluminum oxide, 40 to 65 wt% of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate, and 0.1 to 1 wt% of dimethyl phthalate.

2. In paragraph 1, An insulating film composition for a silicon carbide substrate for a ceramic heater, characterized in that the first and second agents are mixed and used in a weight ratio of 1:0.9 to 1.

1.

3. In paragraph 2, The coefficient of thermal expansion (CTE) of the insulating film composition in which the first and second agents are mixed is 3.85×10 -6 / ℃~3.90×10 -6 An insulating film composition for a silicon carbide substrate for a ceramic heater characterized by having a temperature of / ℃.

4. In paragraph 2 or 3, The first and second agents are mixed and used in a weight ratio of 1:

1. The coefficient of thermal expansion (CTE) of the composition in which the first and second agents are mixed is 3.90×10 -6 / ℃, An insulating film composition for a silicon carbide substrate for a ceramic heater, characterized in that when an insulating film is formed by printing with a thickness of 60㎛ on a 2t thick SiC substrate with a wafer size of 12 inches or 8 inches, the flatness of the substrate is 30 to 40㎛ after firing at 800 to 1000℃ for 60 minutes.

Images