KR100878069B1 - Dielectric film with low coefficient of thermal expansion ??? using liquid crystalline resin - Google Patents

Abstract

One embodiment of the present invention is a technique for providing a dielectric film material having a controllable coefficient of thermal expansion (CTE). A first compound is formed comprising the first liquid crystal component. The first compound is cast to the first membrane. The first film is oriented in a magnetic or electromagnetic field in the first direction. The first film is cured at the first temperature.

Dielectric Film, First Liquid Crystal Component, First Compound, Cast, Curing, Electromagnetic Field

Description

Dielectric film with low coefficient of thermal expansion (CTE) USING LIQUID CRYSTALLINE RESIN}

Embodiments of the present invention relate to semiconductors and, in particular, to semiconductor materials.

Next-generation die interlayer dielectric (ILD) materials are porous and have inferior mechanical strength. Low CTE materials are required to reduce stresses on the ILD due to a coefficient of thermal expansion (CTE) mismatch between the materials in the package. In addition, due to the need for materials flowing over longer distances through narrower gaps, it is desirable to eliminate or minimize filler concentrations commonly used to reduce CTE.

Existing techniques for reducing CTE while reducing or eliminating filler concentration have a number of disadvantages. One technique is to increase filler loading and / or cross-link density of dielectric materials. This technique leads to high modulus and high viscosity, and consequently to cohesive and adhesive failure modes.

Embodiments of the present invention may be best understood with reference to the following description and the accompanying drawings, which are used to illustrate embodiments of the present invention.

1A is a diagram illustrating a semiconductor device in which an embodiment of the present invention may be implemented.

1B is a diagram illustrating a semiconductor package according to an embodiment of the present invention.

2 is a diagram illustrating a structure of a dielectric material according to an embodiment of the present invention.

3 is a diagram showing another structure of the dielectric material according to one embodiment of the present invention.

4 is a flowchart illustrating a process for providing a dielectric layer in accordance with an embodiment of the present invention.

5 is a view showing an epoxy resin according to an embodiment of the present invention.

One embodiment of the present invention is a technique for providing a dielectric film material having a controllable coefficient of thermal expansion (CTE). A first compound is formed comprising the first liquid crystal component. The first compound is cast to the first membrane. The first film is oriented in a magnetic or electromagnetic field in the first direction. The first film is cured at the first temperature.

In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures, and techniques have not been shown in order to avoid obscuring the understanding of this description. One embodiment of the invention may be described as a process, which is usually described as a flowchart, flow chart, structure diagram, or block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. The process ends when the operations complete. Processes may correspond to methods, procedures, methods of production or manufacture, and the like.

One embodiment of the present invention is to provide a dielectric material having controllable CTEs. The CTE can be controlled to be a value exceeding 100 ppm / 占 폚 from a small negative value by controlling the amount of the liquid crystal resin at the time of formation (1) and the degree to which the liquid crystal resin is oriented. The material technology addresses the current low CTE requirements and can be scalable for future packages with ultra low CTE requirements. In addition, since the elastic modulus of the liquid crystal resin is greatly reduced at angles other than perpendicular to the direction of orientation, the dielectric film exhibits low modulus in the z direction and becomes elastic with respect to mechanical stability problems due to package movement. One embodiment of the present invention provides dielectric materials useful for a number of applications. Examples of these applications include (1) traditional substrate build-up processes, including copper plating, photoresist deposition, exposure, development, etching, and resist removal, and (2) photo-definable dielectrics. Films (without the use of photoresist), (3) printed circuit board (PCB) fabrication and (4) imprinting.

1A is a diagram illustrating a semiconductor device 100 in which an embodiment of the present invention may be practiced. The semiconductor device 100 includes one substrate layer 110 and two dielectric layers 120 and 130.

Substrate layer 110 may be any suitable semiconductor substrate, such as silicon. During the fabrication process, device elements, sources and drains, such as field oxides, may be formed on the substrate.

The dielectric layer 120 may be deposited on the substrate layer 110. Other layers, such as gates and metal interconnects, may be deposited as part of the traditional semiconductor manufacturing process. The dielectric layer 120 may include a single film or a plurality of films. As shown in FIG. 1A, three films 122, 124, and 126 may form the dielectric layer 120. Each of the films 122, 124, and 126 may have a different CTE in the selected magnetic field direction.

The dielectric layer 130 may be formed under the substrate of the substrate layer 110. This may be optional and may provide additional protection or other functionality. Like the dielectric layer 120, the dielectric layer 130 may include a single film or a plurality of films. As shown in FIG. 1, three films 132, 134, and 136 may be included. Similar to dielectric layer 120, each of the films 132, 134, and 136 may have a different CTE in the selected magnetic field direction.

Any one of the dielectric layers 120 and 130 may be configured to have a controllable CTE in accordance with one embodiment of the present invention. CTEs may be provided with low values. The plurality of films in each of layers 120 and 130 may be oriented in different directions in a magnetic or electromagnetic field with proper magnetic strength, time, temperature, and orientation of the magnetic field. By selecting appropriate values of magnetic field strength, time, temperature, and orientation, controllable CTE values can be achieved. The film may be formed by a material or compound comprising monomers having a general structure as shown in FIGS. 2 and 3.

1B is a diagram illustrating a semiconductor package 140 according to an embodiment of the present invention. The package 140 may be a flip flop package. However, it is contemplated that other types of packages may be used. The package 140 includes a package substrate 145 and a die 150.

Package substrate 145 may be any suitable package substrate, ceramic or organic, high graded epoxy (eg, bismaleimide triazine) and flexible circuit boards such as standard FR4. Package substrate 145 typically has a low CTE. Die 150 may be any semiconductor die. It may include integrated circuits (eg, processors, memory), devices, compounds, and the like. The underfill 155 may be an adhesive that bonds the entire surface of the chip to the substrate. It is usually epoxy.

Die 150 may have bumps 160. Any suitable type of bumps may be used, such as Controlled Collapse Chip Connection (C4), plated bumps, stud bumps, and the like. Bumps 160 may provide conductive paths electrically and thermally to substrate 145. They can serve as a part of the mechanical mounting of the die to the substrate 145 and can act as a short lead that relieves the mechanical strain between the substrate and the board.

Substrate 145 may include dielectric layer 165, traces and vias 170, and substrate core 175. Dielectric layer 165 may have a controllable CTE to conform to substrate core 175 provided by one embodiment of the present invention. Traces and vias 170 may provide contacts and electrical paths to the substrate. The substrate core 175 may be made of any suitable material, such as epoxy.

2 illustrates a structure 200 of a dielectric material in accordance with an embodiment of the present invention.

Structure 200 includes a liquid crystal segment 210, two elements, both 222 and 224, both marked "X", and (CH ₂ ) n. The liquid crystal segment 210 may be a rod-like liquid crystal component. Each of the two X elements 222 and 224 may be independently selected from the group of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine. The integer n in (CH ₂ ) n may be a value between 1 and 20. The monomer formed by the structure 200 may have a melting point lower than approximately 200 ° C.

3 illustrates another structure 300 of a dielectric material in accordance with one embodiment of the present invention.

Structure 300 may include liquid crystal segment 310, two elements X 322 and 324, (CH ₂ ) n, and two elements Y 332 and 334. The liquid crystal segment 310 may be a rod type liquid crystal component. Each of the two elements X and Y 322, 324, 332, and 334 can be independently selected from the group of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine. The integer n in (CH ₂ ) n may be a value between 2 and 20. The monomer formed by structure 300 may also have a melting point lower than approximately 200 ° C.

Dielectric materials formed by structures 200 and 300 include solvents, one or more catalysts, additives such as one or more fillers, adhesion promoters, mold release agents ( Other additives such as mold release agents, colorants, stabilizers, flame retardants, and other additives known to those skilled in the art may be added.

In one embodiment of the invention, the formed dielectric material can be cast into a film, oriented by a magnetic or electromagnetic field, and then used to prepare as a substrate. In addition, it may be useful to use a solvent as a diluent to assist in the orientation and film formation of the liquid crystal resin.

In another embodiment of the invention, the dielectric material is cast into a film, laminated to a substrate, orientated by a magnetic or electromagnetic field, typically cured at an elevated temperature above the melting point of the resin, and then used to prepare the substrate. Can be. Magnetic or electromagnetic orientation of the dielectric film may be performed with respect to the cast film prior to drying the solvent used and during curing. The degree of liquid crystal resin orientation that can affect CTE properties can be controlled by magnetic or electromagnetic strength, time, temperature, and orientation of magnetic or electromagnetic fields.

The dielectric layer may also include multiple dielectric films as shown in FIG. The dielectric films may comprise liquid crystal resin formed in different orientation directions and / or at different degrees as described above to provide the desired two or three dimensional properties. For example, three films can be used to orient in the x, y, and z directions.

4 is a diagram illustrating a process 400 for providing a dielectric film in accordance with one embodiment of the present invention.

After initiation, process 400 forms a compound comprising a liquid crystal component (block 410). The compound has a structure as shown in FIGS. 2 and 3. Process 400 then casts the compound to the film (block 420). Process 400 then orients the film in a magnetic or electromagnetic field in direction k (block 430). The direction k can be the x direction, the y direction, or the z direction as desired.

Process 400 then cures the film at a certain temperature (block 440). This temperature is typically higher than the melting point of the resin, for example higher than 200 ° C. The process 400 then deposits the film on the substrate or on another suitable film (block 450). Next, process 400 determines if additional layers are required (block 460). If so, the process 400 returns to block 410 again to repeat the process with the same or different magnetic strength, time, temperature, and orientation. Otherwise, process 400 ends.

Experiments were performed to provide quantitative data for the dielectric materials described above. The experiments were performed with and without magnetic or electromagnetic orientation, and with and without fillers. The results confirm that controllable CTEs are achieved in different directions of orientation.

In the first experiment, a dielectric film was formed without magnetic or electromagnetic orientation. 210 parts of methyl ethyl ketone, 20 parts of diglycidyl Bisphenol-A, 20 parts of tetrabromo Bisphenol-A, ortho 20 parts of ortho-cresol novolak epoxy resin (215 g / eq), 15 parts of epoxy-terminated polybutadiene rubber, brominated phenolic novolac 50 parts of brominated phenolic novolak resin, 2,4-diamino-6- (2-methyl-imadizolyreyl) -1,3,5-triazine.isocyanuric acid adduct 4 parts of 2,4-diamino-6- (2-methyl-1-imadizolylethyl) -1,3,5-triazine.isocyanuric acid adduct), and 11 parts of silica (with a maximum particle size of 5 micrometers) A mixture was formed that includes these. These components were added to a planetary mixer, heated to about 80 ° C., and mixed at 50 rpm (revolutions per minute) for about 1 hour. The mixture was then passed twice through a 2-roll mill at about 80 ° C. The mixture was cast into a 40 micrometer thick Mylar membrane and dried at about 100 ° C. for 15 minutes to give a total film thickness of about 70 micrometers. The film was then deposited on the substrate material by vacuum lamination at about 120 ° C. and 1 torr. The film was cured at about 170 ° C. for 2 hours. The dielectric layer thus prepared had a CTE of about 65 ppm in the x, y plane and z direction of the film.

In the second embodiment, the procedure described in the first experiment was repeated except that a magnetic field of about 0.3 Tesla was applied while curing the multilayer structure. The dielectric layer thus prepared had a CTE of about 80 ppm in the x, y plane of the film and about 40 ppm in the z direction. This experiment shows that the CTE of each film in different orientations can be controlled to be different. Moreover, low values of CTE (eg 40 ppm) can also be achieved.

In a third embodiment, 210 parts of methyl ethyl ketone, 60 parts of epoxy resin B (shown in FIG. 5), 20 parts of ortho-cresol novolac epoxy resin (215 g / eq), epoxy-terminated 15 parts of polybutadiene rubber, 50 parts of brominated phenolic novolac resin, 2,4-diamino-6- (2-methyl-1-imadizolyreyl) -1,3,5-tri A mixture was formed comprising four portions of the azine.isocyanuric acid adduct and eleven portions of silica (of a maximum particle size of 5 microns). These components were added to the planetary mixture, heated to about 80 ° C. and mixed at 50 rpm for about 1 hour. The mixture was then passed twice through a two-roll mill at about 80 ° C. The mixture was cast on a 40 micrometer thick mylar membrane. The film was placed in a magnetic field of about 0.3 Tesla in the z direction for 30 minutes, and then dried in the magnetic field at about 100 ° C. for about 15 minutes to give a total film thickness of about 70 micrometers. The film was then laminated to the substrate material by vacuum lamination at about 120 ° C. and 1 torr. The film was cured at about 170 ° C. for 2 hours. The dielectric layer thus prepared had a CTE of about 75 ppm in the x, y plane of the film and about 50 ppm in the z direction.

In the fourth embodiment, the procedure described in the third embodiment is repeated except that fillers are not used. The dielectric layer thus prepared had a CTE of about 125 ppm in the x, y plane of the film and about 5 ppm in the z direction. This experiment illustrates that without fillers, very low CTE values (eg 5 ppm) can be achieved in the selected orientation or direction.

5 is a view showing an epoxy resin B according to an embodiment of the present invention. Epoxy Resin B was used in the third experiment to produce a mixture.

While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described but may be practiced with modifications and variations within the spirit and scope of the appended claims. The present specification is to be regarded as illustrative instead of restrictive.

Claims (30)

Forming a first compound comprising a first liquid crystal component, Casting the first compound into a first film, Orienting the first film in a magnetic or electromagnetic field in a first direction, and Curing the first film at a first temperature How to include. The method of claim 1, Adding at least one additive to the first compound. The method of claim 2, Adding the at least one additive, At least one selected from the group consisting of a catalyst, an adhesive, an adhesion promoter, a mold release agent, a flame retardant, a stabilizer, and a colorant Adding an additive of the. The method of claim 1, Adding a filler to the first compound. The method of claim 1, Laminating the first film to a substrate. The method of claim 1, Forming the first compound, A rod-like liquid crystal component; An element that is one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; And (CH ₂ ) n-n is 1 to 20-forming said first compound. The method of claim 1, Forming the first compound, A rod type liquid crystal component; First and second elements, each being one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; Forming a first compound comprising (CH ₂ ) n-n is 2 to 20. The method of claim 1, Forming a second compound comprising a second liquid crystal component, Casting the second compound into a second film, Orienting the second film in the magnetic or electromagnetic field in a second direction, and Forming a multilayer comprising at least the first and second films How to include more. The method of claim 8, Curing the multilayer at a second temperature. 10. The method of claim 9, wherein at least one of the first and second temperatures is higher than the melting point of one of the first and second compounds. And a first film cast from a first compound comprising a first liquid crystal component, the first film being oriented in a magnetic or electromagnetic field in a first direction and cured at a first temperature. 12. The dielectric layer of claim 11 wherein the first film comprises at least one additive added to the first compound. The dielectric layer of claim 12, wherein the at least one additive comprises one of a catalyst, an adhesive, an adhesion promoter, a mold release agent, a flame retardant, a stabilizer, and a colorant. 12. The dielectric layer of claim 11, wherein the first film further comprises a filler added to the first compound. 12. The dielectric layer of claim 11 wherein said first film is deposited over a substrate. The method of claim 11, The first compound, A rod type liquid crystal component; An element that is one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; And (CH ₂ ) n-n is 1 to 20- Dielectric layer comprising a. The method of claim 11, The first compound, A rod type liquid crystal component; First and second elements, each being one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; And (CH ₂ ) n-n is 2 to 20- Dielectric layer comprising a. The method of claim 11, A second film cast from a second compound comprising a second liquid crystal component, the second film being oriented in the magnetic or electromagnetic field in a second direction, the second film being combined with the first film to form a multilayer Dielectric layer. 19. The dielectric layer of claim 18, wherein the multilayer is cured at a second temperature. 20. The dielectric layer of claim 19 wherein at least one of the first and second temperatures is higher than the melting point of one of the first and second compounds. Substrate layer, and A dielectric layer over the substrate layer As a device comprising: The dielectric layer, And a first film cast from a first compound comprising a first liquid crystal component, the first film being oriented in a magnetic or electromagnetic field in a first direction and cured at a first temperature. The method of claim 21, wherein the first film, At least one additive added to the compound. The apparatus of claim 22, wherein the at least one additive comprises one of a catalyst, an adhesive, an adhesion promoter, a mold release agent, a flame retardant, a stabilizer, and a colorant. The device of claim 21, wherein the first membrane further comprises a filler added to the first compound. 22. The apparatus of claim 21, wherein the first film is stacked over the substrate layer. The method of claim 21, The first compound, A rod type liquid crystal component; An element that is one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; And (CH ₂ ) n-n is 1 to 20- Device comprising a. The method of claim 21, wherein the first compound, A rod type liquid crystal component; First and second elements, each being one of oxygen, carbonyl, carboxyl, oxycarbonyl, and amine; And (CH ₂ ) n-n is 2 to 20- Device comprising a. The method of claim 21, wherein the dielectric layer, A second film cast from a second compound comprising a second liquid crystal component, the second film being oriented in the magnetic or electromagnetic field in a second direction, the second film being combined with the first film to form a multilayer Device. The apparatus of claim 28, wherein the multilayer is cured at a second temperature. 30. The apparatus of claim 29, wherein at least one of the first and second temperatures is higher than the melting point of one of the first and second compounds.

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