A polyurethane polishing pad substrate for chemical mechanical polishing and a method of making the same

Abstract

The application belongs to the technical field of chip manufacturing, and particularly relates to a polyurethane polishing pad substrate for chemical mechanical grinding and a preparation method thereof. The preparation method of the polyurethane polishing pad substrate for chemical mechanical grinding comprises the following steps: (1) preparation of a prepolymer: reacting a terminal hydroxyl compound and an organic polyisocyanate to obtain the prepolymer; (2) uniformly mixing the prepolymer, 3,5-dimethylthio toluene diamine and a foaming agent, heating and curing, and aging to obtain the polyurethane polishing pad substrate for chemical mechanical grinding; the terminal hydroxyl compound is polytetrahydrofuran diol and / or polycaprolactone diol; and the organic polyisocyanate is dicyclohexyl methane diisocyanate. The polyurethane polishing pad substrate for chemical mechanical grinding can be matched with more fillers while keeping the performance of similar products, and the service life is greatly improved and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of chip manufacturing technology, specifically relating to a polyurethane polishing pad substrate for chemical mechanical polishing and its preparation method. Background Technology

[0002] CMP (Chemical Mechanical Polishing) pads are products needed to improve the integration of semiconductors. They are used to polish the surface of semiconductor wafers through physical and chemical reactions, making the surface of the semiconductor wafer flat. With the increasing production of products such as 3D Nand Flash, CMP pads have become a consumable with ever-increasing demand.

[0003] Traditional polishing pads use polyurethane substrate, which has a low hardness range, limited compatibility with fillers, and most importantly, a short lifespan (typically 45-75 hours), which has a significant impact on chip production efficiency and cost.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a polyurethane polishing pad substrate for chemical mechanical abrasives, so as to solve or improve at least one of the problems of short service life, low hardness range and limited compatibility of traditional polishing pads.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a polyurethane polishing pad substrate for chemical mechanical polishing, comprising the following steps: (1) preparation of a prepolymer: reacting a hydroxyl-terminated compound with an organic polyisocyanate to obtain a prepolymer; (2) mixing the prepolymer, 3,5-dimethylthiotoluene diamine and a foaming agent evenly, heating and curing, and aging to obtain the polyurethane polishing pad substrate for chemical mechanical polishing; wherein the hydroxyl-terminated compound is polytetrahydrofuran diol and / or polycaprolactone diol; and the organic polyisocyanate is dicyclohexylmethane diisocyanate.

[0007] Preferably, the molecular weight of the terminal hydroxyl compound is 2000-4000.

[0008] Preferably, in step (1), the amount of the terminal hydroxyl compound is 150-295 parts by weight, and the amount of the organic polyisocyanate is 100 parts by weight.

[0009] Preferably, in step (2), the amount of the prepolymer is 100 parts by weight, the amount of 3,5-dimethylthiotoluene diamine is 9-15 parts by weight, and the amount of the foaming agent is 3-5 parts by weight.

[0010] Preferably, the foaming agent is at least one of Matsunori oil, ACP-2, or sodium bicarbonate.

[0011] Preferably, in step (1), the reaction temperature is 85-95℃ and the reaction time is 1.5-3h.

[0012] Preferably, in step (2), the heating and curing temperature is 120-130℃ and the curing time is 2-5h.

[0013] Preferably, in step (2), the aging temperature is 100-120℃ and the aging time is 10-14h.

[0014] Preferably, before step (1), the method further includes a step of dehydrating the terminal hydroxyl compound; the dehydration includes: dehydrating the terminal hydroxyl compound at 110-120℃ and -0.09 to -0.1MPa for 1.5-2.5h.

[0015] The present invention also proposes a polyurethane polishing pad substrate for chemical mechanical polishing, which adopts the following technical solution: a polyurethane polishing pad substrate for chemical mechanical polishing, wherein the polyurethane polishing pad substrate for chemical mechanical polishing is prepared by the method described above.

[0016] Beneficial effects:

[0017] The polyurethane polishing pad substrate for chemical mechanical abrasion of the present invention can accommodate more fillers while maintaining the performance of similar products, and significantly improves the service life. It can seamlessly replace existing polyurethane substrates, reduce costs, and provides conditions for further development of polishing pads. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0019] Figure 1 A photograph of a finished polishing pad made from the polyurethane polishing pad substrate for chemical mechanical polishing provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0021] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0022] This invention addresses at least one of the problems of short service life, low hardness range, and limited compatibility of fillers in traditional polishing pads by providing a method for preparing a polyurethane polishing pad substrate for chemical mechanical polishing. The method for preparing the polyurethane polishing pad substrate for chemical mechanical polishing according to an embodiment of this invention includes the following steps: (1) Preparation of a prepolymer: reacting a hydroxyl-terminated compound with an organic polyisocyanate to obtain a prepolymer; (2) mixing the prepolymer, 3,5-dimethylthiotoluene diamine, and a foaming agent evenly, heating and curing, and aging to obtain the polyurethane polishing pad substrate for chemical mechanical polishing; the hydroxyl-terminated compound is polytetrahydrofuran diol and / or polycaprolactone diol; the organic polyisocyanate is dicyclohexylmethane diisocyanate.

[0023] To address the shortcomings of existing products, this invention develops a substrate specifically for CMP (Chemical Mechanical Polishing) polishing pads based on a polyurethane system. While maintaining the performance of similar products, it significantly improves service life and can accommodate a wider range of fillers, thus paving the way for further development of polishing pads. This invention utilizes 3,5-dimethylthiotoluenediamine as a curing agent. This curing agent has a low reaction rate at low temperatures, which, when used in the preparation of the polyurethane polishing pad substrate for chemical mechanical polishing, meets the open time requirement (over 6 hours) (CMP-based adhesives generally have an open time greater than 6 hours due to subsequent processing requirements).

[0024] In a preferred embodiment of the present invention, the amount of the hydroxyl-terminated compound is 150-295 parts by weight (e.g., 150 parts by weight, 180 parts by weight, 210 parts by weight, 240 parts by weight, 270 parts by weight, or 295 parts by weight), and the amount of the organic polyisocyanate is 100 parts by weight. The ratio of the hydroxyl-terminated compound to the organic polyisocyanate significantly affects the performance of the product: if the amount of the hydroxyl-terminated compound is too small and the amount of the organic polyisocyanate is too large (excessive urethane groups), the product will have high hardness, shortening its service life; if the amount of the hydroxyl-terminated compound is too large and the amount of the organic polyisocyanate is too small, the product will have poor curing effect and low hardness, making it unusable as a base adhesive (the finished product after cross-linking and curing of the prepolymer).

[0025] In a preferred embodiment of the present invention, the molecular weight of the hydroxyl-terminated compound is 2000-4000 (e.g., 2000, 2500, 3000, 3500, or 4000). If the molecular weight of the hydroxyl-terminated compound is too small, the resulting polyurethane polishing pad substrate for chemical mechanical polishing will not have sufficient strength; if the molecular weight is too large, the resulting polyurethane polishing pad substrate for chemical mechanical polishing will have excessively high hardness.

[0026] In a preferred embodiment of the present invention, in step (2), the amount of prepolymer is 100 parts by weight, the amount of 3,5-dimethylthiotoluene diamine is 9-15 parts by weight (e.g., 9, 10, 11, 12, 13, 14, or 15 parts by weight), and the amount of foaming agent is 3-5 parts by weight (e.g., 3, 4, or 5 parts by weight). If the amount of 3,5-dimethylthiotoluene diamine (curing agent) is too high, there will be excessive molecular cross-linking and high hardness; if the amount of 3,5-dimethylthiotoluene diamine (curing agent) is too low, the reaction rate will be slow, and too much isocyanate will be consumed. The foaming agent in this invention mainly plays a role in adjusting the density and hardness of the system; if the foaming agent content is too high, the foaming ratio is large, the cells are large, and the structural strength is poor; if the foaming agent content is too low, the base adhesive has high hardness and poor toughness.

[0027] In a preferred embodiment of the present invention, the foaming agent is at least one of Matsumoto oil, ACP-2, or sodium bicarbonate. Matsumoto oil is a microsphere foaming agent, a low-boiling-point hydrocarbon foaming agent, exhibiting good foaming uniformity, controllable cell structure, and a wide adjustment range. ACP-2 foaming agent has good compatibility, uniform foaming, and smaller cells, making it suitable for preparing closed-cell microfoam systems. Using sodium bicarbonate as a foaming agent offers low cost, a wide dosage adjustment range, and the ability to adjust between open and closed-cell structures.

[0028] In a preferred embodiment of the present invention, in step (1), the reaction temperature is 85-95℃ (e.g., 85℃, 87℃, 89℃, 91℃, 93℃ or 95℃), and the reaction time is 1.5-3h (e.g., 1.5h, 1.8h, 2.1h, 2.4h, 2.7h or 3h).

[0029] In a preferred embodiment of the present invention, in step (2), the heating and curing temperature is 120-130℃ (e.g., 120℃, 122℃, 124℃, 126℃, 128℃, or 130℃), and the curing time is 2-5 hours (e.g., 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours). If the curing temperature is too low, the reaction time will be too long; if the curing temperature is too high, the reaction rate will be too fast, resulting in uneven reaction and uneven hardness.

[0030] In a preferred embodiment of the present invention, in step (2), the curing temperature is 100-120℃ (e.g., 100℃, 104℃, 108℃, 112℃, 116℃, or 120℃), and the curing time is 10-14h (e.g., 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, or 14h). If the curing temperature is too low, the curing will be incomplete, and the hardness and shrinkage rate of the subsequent product will change; if the curing temperature is too high, the molecular chains will be fixed too quickly, resulting in poor performance.

[0031] In a preferred embodiment of the present invention, before step (1), a step of dehydrating the terminal hydroxyl compound is further included; the dehydration includes: dehydrating the terminal hydroxyl compound at 110-120°C (e.g., 110°C, 112°C, 114°C, 116°C, 118°C or 120°C) and -0.09 to -0.1 MPa (e.g., -0.09 MPa, -0.092 MPa, -0.094 MPa, -0.096 MPa, -0.098 MPa or -0.1 MPa) for 1.5-2.5 h (e.g., 1.5 h, 1.7 h, 1.9 h, 2.1 h, 2.3 h or 2.5 h).

[0032] The present invention also proposes a polyurethane polishing pad substrate for chemical mechanical polishing, wherein the polyurethane polishing pad substrate for chemical mechanical polishing in the embodiments of the present invention is prepared by the method described above.

[0033] The polyurethane polishing pad substrate for chemical mechanical polishing of the present invention will be described in detail below through specific embodiments.

[0034] In the following embodiment:

[0035] Example 1

[0036] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment includes the following steps:

[0037] (1) 295 parts by weight of polytetrahydrofuran diol (Mitsubishi Chemical Corporation PTMG2000, average molecular weight 2000 g / mol) were dehydrated at 110℃ and -0.09 MPa for 2 h.

[0038] (2) Preparation of prepolymer A: The polytetrahydrofuran diol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer A;

[0039] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 9 parts by weight of prepolymer A100, 3,5-dimethylthiotoluene diamine (DMTDA) and 3 parts by weight of foaming agent F-50 (Matsumoto oil) are mixed and stirred evenly, then poured into a mold cavity, heated and cured in an oven at 120°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0040] Example 2

[0041] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment includes the following steps:

[0042] (1) 295 parts by weight of polytetrahydrofuran diol (Mitsubishi Chemical Corporation PTMG2000, average molecular weight 2000 g / mol) were dehydrated at 110℃ and -0.09 MPa for 2 h.

[0043] (2) Preparation of prepolymer A: The polytetrahydrofuran diol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer A;

[0044] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 9 parts by weight of prepolymer A100, 3,5-dimethylthiotoluene diamine (DMTDA) and 3 parts by weight of foaming agent ACP-2 (Hailite Chemical) were mixed and stirred evenly, then poured into a mold cavity and cured in an oven at 130°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0045] Example 3

[0046] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment includes the following steps:

[0047] (1) 295 parts by weight of polytetrahydrofuran diol (Mitsubishi Chemical Corporation PTMG2000, average molecular weight 2000 g / mol) were dehydrated at 110℃ and -0.09 MPa for 2 h.

[0048] (2) Preparation of prepolymer A: The polytetrahydrofuran diol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer A;

[0049] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 00 parts by weight of prepolymer A100, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA), 5 parts by weight of foaming agent sodium bicarbonate, and 0.5 parts by weight of stearic acid (to adjust pH) were mixed and stirred evenly, then poured into a mold cavity and cured in an oven at 130°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0050] Example 4

[0051] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment includes the following steps:

[0052] (1) 150 parts by weight of polytetrahydrofuran diol (Mitsubishi Chemical Corporation PTMG2000, average molecular weight 2000 g / mol) were dehydrated at 110℃ and -0.09 MPa for 2 h.

[0053] (2) Preparation of prepolymer A: The polytetrahydrofuran diol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer B;

[0054] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 100 parts by weight of prepolymer B1, 15 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and 3 parts by weight of foaming agent F-50 (Matsumoto oil) were mixed and stirred evenly, and then poured into the mold cavity. The mixture was heated and cured in an oven at 130°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0055] Example 5

[0056] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment includes the following steps:

[0057] (1) 295 parts by weight of polycaprolactone diol (Japan Daicel PCL220N, average molecular weight 2000 g / mol) were dehydrated at 110℃ and -0.09 MPa for 2 h.

[0058] (2) Preparation of prepolymer C: The polycaprolactone diol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer C;

[0059] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 9 parts by weight of prepolymer C100, 3,5-dimethylthiotoluene diamine (DMTDA) and 3 parts by weight of foaming agent F-50 (Matsumoto oil) are mixed and stirred evenly, then poured into a mold cavity, heated and cured in an oven at 120°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0060] Comparative Example 1

[0061] The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing in this comparative example includes the following steps:

[0062] (1) 295 parts by weight of polypropylene glycol (Lanxing Dongda DL-2000D, average molecular weight 2000g / mol) were dehydrated at 110℃ and -0.09MPa for 2h;

[0063] (2) Preparation of prepolymer D: The polypropylene glycol obtained by dehydration treatment in step (1) is cooled to 90°C, and dicyclohexylmethane diisocyanate (H) is added. 12 100 parts by weight of MDI were reacted for 2 hours to obtain prepolymer D;

[0064] (3) Preparation of polyurethane polishing pad substrate for chemical mechanical polishing (CMP adhesive): 9 parts by weight of prepolymer D100, 3,5-dimethylthiotoluene diamine (DMTDA) and 3 parts by weight of foaming agent F-50 (Matsumoto oil) were mixed and stirred evenly, then poured into a mold cavity and cured in an oven at 120°C for 3 hours, and then cured in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing in this embodiment.

[0065] Comparative Example 2

[0066] The only difference between this comparative example and Example 1 is that the curing temperature is 100°C, while all other aspects remain the same as in Example 1.

[0067] Comparative Example 3

[0068] The only difference between this comparative example and Example 1 is that the curing temperature is 150°C, while all other aspects remain the same as in Example 1.

[0069] Comparative Example 4

[0070] The only difference between this comparative example and Example 1 is that the amount of foaming agent F-50 used is 8 parts by weight, while the rest are the same as in Example 1.

[0071] Experimental Example

[0072] The properties of the polyurethane polishing pad substrate for chemical mechanical polishing prepared in the examples and the product prepared in the comparative examples were tested.

[0073] Among them, the abrasion resistance test (service life) was conducted in accordance with "QB-11QBT 2726-2005 Leather Abrasion Resistance".

[0074] The Shore A hardness is obtained by testing with a hardness tester.

[0075] The density was obtained by measuring with a density balance.

[0076] The melting point is determined based on DSC data.

[0077] The “compression modulus” is obtained by testing in accordance with GB / T 1041 Test Method for Compression Properties of Plastics.

[0078] The test results are shown in Table 1 below:

[0079] Table 1

[0080]

[0081] In summary:

[0082] As can be seen from Examples 1-5, the polyurethane polishing pad substrate for chemical mechanical polishing of the present invention not only meets various performance requirements, but also has a long service life of more than 95 hours.

[0083] As can be seen from Example 1 and Comparative Example 1, the present invention, by selecting polytetrahydrofuran diol as a hydroxyl-terminated compound for the preparation of polyurethane polishing pad substrate for chemical mechanical polishing, can significantly improve the service life of polyurethane polishing pad substrate for chemical mechanical polishing compared to polypropylene diol (which, when used in the present invention, leads to poor toughness and low service life of the cross-linked polymerized product).

[0084] As can be seen from Example 1 and Comparative Examples 2-3, both excessively high and low curing temperatures will adversely affect the foaming effect, resulting in excessively high product hardness, which does not meet the requirements of chemical mechanical polishing for the polishing pad substrate. When the curing temperature is too high, it may exceed the glass transition temperature of the polymer material, causing the foaming agent to evaporate rapidly to the outside of the bulk phase without forming a large number of cells inside the bulk phase.

[0085] As can be seen from Example 1 and Comparative Example 4, if too much foaming agent is used, the foam cells will be too large and the foam cell walls will be thinner, resulting in a decrease in the specific strength of the product and a reduction in its service life.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a polyurethane polishing pad substrate for chemical mechanical polishing, characterized in that, The preparation method consists of the following steps: (1) Dehydration of terminal hydroxyl compounds; (2) Preparation of prepolymer: The prepolymer is obtained by reacting the terminal hydroxyl compound with the organic polyisocyanate; (3) Mix the prepolymer, 3,5-dimethylthiotoluenediamine and foaming agent evenly, heat to cure and mature, and obtain the polyurethane polishing pad substrate for chemical mechanical abrasion. The hydroxyl-terminated compound is polytetrahydrofuran diol and / or polycaprolactone diol, and the molecular weight of the hydroxyl-terminated compound is 2000-4000. The organic polyisocyanate is dicyclohexylmethane diisocyanate; In step (2), the amount of the terminal hydroxyl compound is 150-295 parts by weight, and the amount of the organic polyisocyanate is 100 parts by weight; in step (2), the reaction temperature is 85-95℃, and the reaction time is 1.5-3h. In step (3), the amount of the prepolymer is 100 parts by weight, the amount of 3,5-dimethylthiotoluene diamine is 9-15 parts by weight, and the amount of the foaming agent is 3-5 parts by weight. The foaming agent is at least one of F-50, ACP-2, or sodium bicarbonate. In step (3), the temperature for heating and curing is 120-130°C, and the curing time is 2-5 hours. In step (3), the temperature for aging is 100-120°C, and the aging time is 10-14 hours.

2. The method for preparing the polyurethane polishing pad substrate for chemical mechanical polishing according to claim 1, characterized in that, The dehydration includes: dehydrating the terminal hydroxyl compound at 110-120°C and -0.09 to -0.1 MPa for 1.5-2.5 hours.

3. A polyurethane polishing pad substrate for chemical mechanical polishing, characterized in that, The polyurethane polishing pad substrate for chemical mechanical polishing is prepared using the method described in claim 1 or 2.

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