CN116082600A - Polyurethane polishing pad substrate for chemical mechanical polishing and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of chip manufacturing, and particularly relates to a polyurethane polishing pad substrate for chemical mechanical polishing and a preparation method thereof. The preparation method of the polyurethane polishing pad substrate for chemical mechanical polishing comprises the following steps: (1) preparation of a prepolymer: reacting a hydroxyl-terminated compound with an organic polyisocyanate to obtain a prepolymer; (2) Uniformly mixing the prepolymer, 3, 5-dimethyl thiotoluene diamine and a foaming agent, heating, curing and curing to obtain a 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. The polyurethane polishing pad base material for chemical mechanical polishing can be adapted to more fillers while maintaining the performance of similar products, and greatly prolongs the service life and reduces the cost.

Description

Polyurethane polishing pad substrate for chemical mechanical polishing and preparation method thereof

technical field

The invention belongs to the technical field of chip manufacturing, and in particular relates to a polyurethane polishing pad base material for chemical mechanical grinding and a preparation method thereof.

Background technique

CMP polishing pad (Chemical Mechanical Polishing Pad) is a product required to improve the integration of semiconductors. It is polished by physical and chemical reactions on the surface of the semiconductor wafer to make the surface of the semiconductor wafer flat. With the increase in the output of products such as 3D Nand Flash, CMP polishing pads have become a consumable with increasing demand.

Traditional polishing pads use polyurethane substrates, which have a low hardness range, limited suitable fillers, and most importantly, short service life (generally 45-75 hours), which has a great impact on chip production efficiency and cost.

Therefore, it is necessary to provide an improved technical solution for the above-mentioned deficiencies in the prior art.

Contents of the invention

The object of the present invention is to provide a polyurethane polishing pad base material for chemical mechanical polishing to solve or improve at least one of the problems of short service life, low hardness range and limited suitable fillers of traditional polishing pads.

In order to achieve the above object, the present invention provides the following technical scheme: a preparation method of polyurethane polishing pad base material for chemical mechanical polishing, comprising the following steps: (1) preparation of prepolymer: reacting hydroxyl-terminated compound and organic polyisocyanate , to obtain a prepolymer; (2) mix the prepolymer, 3,5-dimethylthiotoluenediamine and foaming agent uniformly, heat and solidify, and ripen to obtain the polyurethane polishing pad for chemical mechanical polishing Substrate; the hydroxyl-terminated compound is polytetrahydrofuran diol and/or polycaprolactone diol; the organic polyisocyanate is dicyclohexylmethane diisocyanate.

Preferably, it is characterized in that the molecular weight of the hydroxyl-terminated compound is 2000-4000.

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

Preferably, in step (2), the amount of the prepolymer is 100 parts by weight, the amount of the 3,5-dimethylthiotoluenediamine is 9-15 parts by weight, the amount of the blowing agent It is 3-5 parts by weight.

Preferably, the foaming agent is at least one of Matsumoto oil, ACP-2 or sodium bicarbonate.

Preferably, in step (1), the reaction temperature is 85-95°C, and the reaction time is 1.5-3h.

Preferably, in step (2), the heating and curing temperature is 120-130° C., and the curing time is 2-5 hours.

Preferably, in step (2), the aging temperature is 100-120°C, and the aging time is 10-14h.

Preferably, before step (1), a step of dehydrating the hydroxyl-terminated compound is also included; the dehydration includes: dehydrating the hydroxyl-terminated compound at 110-120° C. at -0.09 to -0.1 MPa for 1.5-2.5 h.

The present invention also proposes a polyurethane polishing pad base material for chemical mechanical grinding, which adopts the following technical scheme: a polyurethane polishing pad base material for chemical mechanical grinding, and the polyurethane polishing pad base material for chemical mechanical grinding is as described above. prepared by the method described above.

Beneficial effect:

The polyurethane polishing pad base material for chemical mechanical grinding of the present invention can be adapted to more fillers while maintaining the performance of similar products, and greatly improves the service life, can seamlessly replace the existing polyurethane base material, and reduce costs ; And provide conditions for the further development of abrasive pads.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. in:

FIG. 1 is a photo of a finished polishing pad made of a polyurethane polishing pad substrate for chemical mechanical polishing provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below, obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention belong to the protection scope of the present invention.

The present invention will be described in detail below in conjunction with examples. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Aiming at at least one of the problems of short service life, low hardness range and limited suitable fillers in the current traditional polishing pads, the present invention provides a method for preparing a polyurethane polishing pad base material for chemical mechanical polishing. The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the embodiment of the present invention comprises the following steps: (1) the preparation of the prepolymer: reacting the terminal hydroxyl compound and the organic polyvalent isocyanate to obtain the prepolymer; (2) Mix the prepolymer, 3,5-dimethylthiotoluenediamine and foaming agent evenly, heat and cure, and mature to obtain the polyurethane polishing pad substrate for chemical mechanical polishing; the terminal hydroxyl compound is polytetrahydrofuran diol and/or Or polycaprolactone diol; organic polyisocyanate is dicyclohexylmethane diisocyanate.

In order to solve the defects of existing products, the present invention is based on the polyurethane system and develops a base material specially used for CMP (chemical mechanical polishing) grinding pads. While maintaining the performance of similar products, the service life is greatly improved, and more fillers can be adapted at the same time , which provides conditions for further development of abrasive pads. The present invention selects 3,5-dimethylthiotoluenediamine as the curing agent, the curing agent has a low reaction rate at low temperature, and when used for the preparation of the polyurethane polishing pad base material for chemical mechanical polishing of the present invention, it can meet the operating requirements. Requirements for time (above 6h) (Due to the needs of subsequent processes, the opening time of CMP-based rubber is generally greater than 6h).

In a preferred embodiment of the present invention, the amount of hydroxyl-terminated compound is 150-295 parts by weight (for example, 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 organic polyisocyanate The dosage is 100 parts by weight. Among them, the ratio of the amount of hydroxyl-terminated compound and organic polyisocyanate will have an important impact on the performance of the product: if the amount of hydroxyl-terminated compound is too small and the amount of organic polyisocyanate is too much (urethane group is excessive), the product will have high hardness and will Shorten the service life; if the amount of hydroxyl-terminated compound is too much and the amount of organic polyisocyanate is too small, the curing effect of the product will be poor, the hardness will be too low, and it cannot be used as a base rubber (the finished product after the prepolymer is cross-linked and cured).

In a preferred embodiment of the present invention, the molecular weight of the hydroxyl-terminated compound is 2000-4000 (eg, 2000, 2500, 3000, 3500 or 4000). If the molecular weight of the terminal hydroxyl group is too small, the strength of the base material of the polyurethane polishing pad for chemical mechanical polishing is insufficient; if the molecular weight is too large, the hardness of the base material of the polyurethane polishing pad for chemical mechanical grinding is too high.

In a preferred embodiment of the present invention, in step (2), the amount of prepolymer is 100 parts by weight, and the amount of 3,5-dimethylthiotoluenediamine is 9-15 parts by weight (for example, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight or 15 parts by weight), the amount of blowing agent is 3-5 parts by weight (for example, 3 parts by weight, 4 parts by weight or 5 parts by weight) . Among them, if the amount of 3,5-dimethylthiotoluenediamine (curing agent) is too much, the molecular crosslinking will be too much and the hardness will be high; if the amount of 3,5-dimethylthiotoluenediamine (curing agent) If the amount is too small, the reaction speed will be slow and too much isocyanate will be consumed. The foaming agent mainly plays the role of adjusting the density and hardness of the system in the present invention; if the content of the foaming agent is too high, the foaming ratio will be large, the cells will be large, and the structural strength will be poor; if the content of the foaming agent is too low, the hardness of the base rubber will be large , poor toughness.

In a preferred embodiment of the present invention, the foaming agent is at least one of Matsumoto oil, ACP-2 or sodium bicarbonate. Among them, Matsumoto oil is a microsphere foaming agent, low boiling point hydrocarbon foaming, good foaming uniformity, controllable cell structure, wide adjustment range; ACP-2 foaming agent, good compatibility, uniform foaming, Smaller cells are suitable for the preparation of closed-cell micro-foaming systems; using sodium bicarbonate as a foaming agent has low cost and a wide range of dosage adjustment, and the opening and closing of cells can be adjusted.

In a preferred embodiment of the present invention, in step (1), the reaction temperature is 85-95°C (for example, 85°C, 87°C, 89°C, 91°C, 93°C or 95°C), and the reaction time is 1.5-3h ( For example, 1.5h, 1.8h, 2.1h, 2.4h, 2.7h or 3h).

In a preferred embodiment of the present invention, in step (2), the heating and curing temperature is 120-130°C (for example, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C), and the curing time is 2- 5h (eg, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h). If the curing temperature is too low, the reaction time will be too long; if the curing temperature is too high, the reaction speed will be too fast, resulting in uneven reaction, which will lead to uneven hardness.

In a preferred embodiment of the present invention, in step (2), the aging temperature is 100-120°C (for example, 100°C, 104°C, 108°C, 112°C, 116°C or 120°C), and the aging time is 10-14h (eg, 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, the hardness of subsequent products will change, and the shrinkage rate will also change; if the curing temperature is too high, the molecular chain will be fixed too quickly and the performance will be poor.

In a preferred embodiment of the present invention, before step (1), a step of dehydrating the hydroxyl-terminated compound is also included; dehydration includes: making the hydroxyl-terminated compound at 110-120°C (for example, 110°C, 112°C, 114°C, 116°C , 118°C or 120°C), -0.09～-0.1MPa (for example, -0.09MPa, -0.092MPa, -0.094MPa, -0.096MPa, -0.098MPa or -0.1MPa) under dehydration for 1.5-2.5h (for example, 1.5h, 1.7h, 1.9h, 2.1h, 2.3h or 2.5h).

The present invention also proposes a polyurethane polishing pad substrate for chemical mechanical polishing. The polyurethane polishing pad substrate for chemical mechanical polishing in the embodiment of the present invention is prepared by the above-mentioned method.

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

In the following example:

Example 1

The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the present embodiment comprises the following steps:

(1) Dehydrating 295 parts by weight of polytetrahydrofuran diol (PTMG2000 from Mitsubishi Chemical Corporation, average molecular weight 2000g/mol) at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer A: cool down the polytetrahydrofuran diol obtained through the dehydration treatment in step (1) to 90° C., add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours to obtain Prepolymer A;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer A, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and foaming agent F- 3 parts by weight of 50 (Matsumoto grease) were mixed and stirred evenly, poured into the mold cavity, heated and cured in an oven at 120°C for 3 hours, and then aged in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing of this embodiment.

Example 2

The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the present embodiment comprises the following steps:

(1) Dehydrating 295 parts by weight of polytetrahydrofuran diol (PTMG2000 from Mitsubishi Chemical Corporation, average molecular weight 2000g/mol) at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer A: cool the polytetrahydrofuran diol obtained through the dehydration treatment in step (1) to 90° C., add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours to obtain Prepolymer A;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer A, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and foaming agent ACP- 2 (Hai Li Chemical) 3 parts by weight were mixed and stirred evenly, poured into the mold cavity, heated and cured in an oven at 130°C for 3 hours, and then aged in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad base material for chemical mechanical polishing in this embodiment .

Example 3

The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the present embodiment comprises the following steps:

(1) Dehydrating 295 parts by weight of polytetrahydrofuran diol (PTMG2000 from Mitsubishi Chemical Corporation, average molecular weight 2000g/mol) at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer A: cool the polytetrahydrofuran diol obtained through the dehydration treatment in step (1) to 90° C., add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours to obtain Prepolymer A;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer A, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and blowing agent bicarbonate After mixing and stirring 5 parts by weight of sodium and 0.5 parts by weight of stearic acid (adjusting the pH), pour it into a mold cavity, heat and solidify in a 130°C oven for 3 hours, and then ripen in a 100°C oven for 12 hours to obtain the chemical mechanical grinding compound of this embodiment. Use a polyurethane polishing pad substrate.

Example 4

The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the present embodiment comprises the following steps:

(1) 150 parts by weight of polytetrahydrofuran diol (PTMG2000 from Mitsubishi Chemical Corporation, average molecular weight 2000g/mol) was dehydrated at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer A: cool down the polytetrahydrofuran diol obtained through the dehydration treatment in step (1) to 90° C., add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours to obtain Prepolymer B;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer B, 15 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and blowing agent F- 3 parts by weight of 50 (Matsumoto oil) were mixed and stirred evenly, poured into the mold cavity, heated and cured in an oven at 130°C for 3 hours, and then aged in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing of this embodiment.

Example 5

The preparation method of the chemical mechanical polishing polyurethane polishing pad base material of the present embodiment comprises the following steps:

(1) Dehydrate 295 parts by weight of polycaprolactone diol (Dacel PCL220N, average molecular weight 2000g/mol) at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer C: lower the temperature of the polycaprolactone diol obtained through the dehydration treatment in step (1) to 90°C, add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours , to obtain prepolymer C;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and blowing agent F- 3 parts by weight of 50 (Matsumoto grease) were mixed and stirred evenly, poured into the mold cavity, heated and cured in an oven at 120°C for 3 hours, and then aged in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing of this embodiment.

Comparative example 1

The preparation method of the polyurethane polishing pad substrate for chemical mechanical grinding of this comparative example comprises the following steps:

(1) Dehydrate 295 parts by weight of polypropylene glycol (Bluestar Dongda DL-2000D, average molecular weight 2000g/mol) at 110°C and -0.09MPa for 2h;

(2) Preparation of prepolymer D: cool down the polypropylene glycol obtained through the dehydration treatment in step (1) to 90°C, add 100 parts by weight of dicyclohexylmethane diisocyanate (H ₁₂ -MDI) and react for 2 hours to obtain a prepolymer D;

(3) Polyurethane polishing pad substrate for chemical mechanical grinding (preparation of CMP glue): 100 parts by weight of prepolymer D, 9 parts by weight of 3,5-dimethylthiotoluenediamine (DMTDA) and foaming agent F- 3 parts by weight of 50 (Matsumoto grease) were mixed and stirred evenly, poured into the mold cavity, heated and cured in an oven at 120°C for 3 hours, and then aged in an oven at 100°C for 12 hours to obtain the polyurethane polishing pad substrate for chemical mechanical polishing of this embodiment.

Comparative example 2

The only difference between this comparative example and Example 1 is that the curing temperature is 100° C., and the rest are consistent with Example 1.

Comparative example 3

The only difference between this comparative example and Example 1 is that the curing temperature is 150° C., and the rest are consistent with Example 1.

Comparative example 4

The only difference between this comparative example and Example 1 is that the amount of blowing agent F-50 is 8 parts by weight, and the rest are consistent with Example 1.

Experimental example

The properties of the polyurethane polishing pad substrates for chemical mechanical polishing prepared in the examples and the products prepared in the comparative examples were tested.

Among them: the wear resistance test (service life) is tested according to "QB-11QBT 2726-2005 Leather Wear Resistance";

"Shore A hardness" is obtained by testing with a hardness tester;

"Density" is detected by a density balance;

"Melting point" is detected according to DSC data;

"Compression modulus" is tested according to "GB/T 1041 Plastic Compression Performance Test Method".

The test results are shown in Table 1 below:

Table 1

In summary:

From Examples 1-5, it can be seen that the polyurethane polishing pad base material for chemical mechanical polishing of the present invention meets various performance requirements and has a high service life of more than 95 hours.

In conjunction with Example 1 and Comparative Example 1, it can be seen that the present invention uses polytetrahydrofuran diol as the terminal hydroxyl compound for the preparation of polyurethane polishing pad substrates for chemical mechanical grinding, compared to polypropylene glycol (polypropylene glycol is used for In the present invention, the product after cross-linking and polymerization will have poor toughness and low service life), which can significantly improve the service life of the polyurethane polishing pad base material for chemical mechanical polishing.

In combination with Example 1 and Comparative Examples 2-3, it can be known that when the curing temperature is too high or too low, the foaming effect will be adversely affected, causing the product hardness to be too high, which does not meet the requirements of chemical mechanical grinding for the base material of the polishing pad . When the curing temperature is too high, it may exceed the glass transition temperature of the polymer material, and the blowing agent quickly volatilizes out of the bulk phase without forming a large number of cells inside the bulk phase.

Combining Example 1 and Comparative Example 4, it can be seen that if the amount of foaming agent is too much, the cells will be too large and the cell walls will be thinner, resulting in a decrease in the specific strength of the product and a decrease in service life.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a preparation method for chemical mechanical grinding polyurethane polishing pad base material, is characterized in that, comprises the following steps: (1) Preparation of the prepolymer: react the hydroxyl-terminated compound with the organic polyisocyanate to obtain the prepolymer; (2) Mix the prepolymer, 3,5-dimethylthiotoluenediamine and foaming agent evenly, heat and solidify, and mature to obtain the polyurethane polishing pad substrate for chemical mechanical polishing; The hydroxyl-terminated compound is polytetrahydrofuran diol and/or polycaprolactone diol; The organic polyvalent isocyanate is dicyclohexylmethane diisocyanate. 2. The preparation method of polyurethane polishing pad substrate for chemical mechanical polishing according to claim 1, characterized in that, the molecular weight of the hydroxyl-terminated compound is 2000-4000. 3. the preparation method of polyurethane polishing pad base material for chemical mechanical grinding according to claim 1, is characterized in that, in step (1), the consumption of described terminal hydroxyl compound is 150-295 weight part, and described organic multivariate The amount of isocyanate is 100 parts by weight. 4. the preparation method of polyurethane polishing pad substrate for chemical mechanical grinding according to claim 1, is characterized in that, in step (2), the consumption of described prepolymer is 100 parts by weight, described 3,5- The amount of dimethylthiotoluenediamine is 9-15 parts by weight, and the amount of the blowing agent is 3-5 parts by weight. 5. the preparation method of polyurethane polishing pad base material for chemical mechanical grinding according to claim 1, is characterized in that, described whipping agent is at least one in Matsumoto oil, ACP-2 or sodium bicarbonate. 6 . The method for preparing a polyurethane polishing pad substrate for chemical mechanical polishing according to claim 1 , wherein in step (1), the reaction temperature is 85-95° C., and the reaction time is 1.5-3 h. 7. the preparation method of polyurethane polishing pad base material for chemical mechanical grinding according to claim 1, is characterized in that, in step (2), the temperature of described heat curing is 120-130 ℃, and the time of curing is 2- 5h. 8. the preparation method of polyurethane polishing pad substrate for chemical mechanical grinding according to claim 1, is characterized in that, in step (2), the temperature of described curing is 100-120 ℃, and the time of curing is 10-14h . 9. according to the preparation method of the chemical mechanical polishing polyurethane polishing pad substrate described in any one of claim 1-8, it is characterized in that, before step (1), also comprise the step that described terminal hydroxyl compound is dehydrated; The dehydration includes: dehydrating the hydroxyl-terminated compound at 110-120°C and -0.09-0.1MPa for 1.5-2.5h. 10. A polyurethane polishing pad substrate for chemical mechanical polishing, characterized in that the polyurethane polishing pad substrate for chemical mechanical polishing is prepared by the method according to any one of claims 1-9.

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