LAMINATE, CURABLE RESIN COMPOSITION, METHOD FOR MANUFACTURING LAMINATE, METHOD FOR MANUFACTURING SUBSTRATE HAVING JUNCTION ELECTRODE, SEMICONDUCTOR DEVICE, AND IMAGE CAPTURING DEVICE

Abstract

The present invention aims to provide a stack having high electrical connection reliability, a curable resin composition used for the stack, a method for producing the stack, a method for producing a substrate having a bonding electrode used for producing the stack, a semiconductor device including the stack, and an imaging device including the stack. Provided is a stack sequentially including: a first substrate having an electrode; an organic film; and a second substrate having an electrode, the electrode of the first substrate and the electrode of the second substrate are electrically connected via a through-hole extending through the organic film.

Claims

1. A stack sequentially comprising: a first substrate having an electrode; an organic film; and a second substrate having an electrode, the electrode of the first substrate and the electrode of the second substrate being electrically connected via a through-hole extending through the organic film.

2. The stack according to claim 1, wherein the organic film has a weight loss of 5% or less after heat treatment at 400° C. for four hours.

3. The stack according to claim 1, wherein the organic film has a surface hardness of 5 GPa or less as measured using a nanoindenter.

4. The stack according to claim 1, wherein the organic film is a cured product of a curable resin composition.

5. The stack according to claim 4, wherein the organic film contains an organosilicon compound.

6. The stack according to claim 5, wherein the organosilicon compound has a structure represented by the following formula (1): ##STR00010## wherein each R.sup.0, R.sup.1, and R.sup.2 independently represents a linear, branched, or cyclic aliphatic group, an aromatic group, or hydrogen; the aliphatic group and the aromatic group may or may not have a substituent; and m and n each represent an integer of 1 or greater.

7. The stack according to claim 5, wherein the organosilicon compound has an aromatic ring structure.

8. The stack according to claim 1, wherein the organic film contains a catalyst that promotes curing reaction.

9. The stack according to claim 1, including an inorganic layer having a thickness of 1 nm or greater and 1 μm or less between the first substrate and the second substrate.

10. The stack according to claim 1, including a barrier metal layer on a surface of the through-hole.

11. A curable resin composition used for forming an organic film of a stack, the stack sequentially including a first substrate having an electrode, the organic film, and a second substrate having an electrode, the electrode of the first substrate and the electrode of the second substrate being electrically connected via a through-hole extending through the organic film.

12. The curable resin composition according to claim 11, wherein a cured product of the curable resin composition has a tensile modulus of elasticity at 25° C. of 1 GPa or less.

13. The curable resin composition according to claim 11, containing a reactive site-containing organosilicon compound.

14. The curable resin composition according to claim 13, wherein the reactive site-containing organosilicon compound has a structure represented by the following formula (1): ##STR00011## wherein each R.sup.0, R.sup.1, and R.sup.2 independently represents a linear, branched, or cyclic aliphatic group, an aromatic group, or hydrogen; the aliphatic group and the aromatic group may or may not have a substituent; and m and n each represent an integer of 1 or greater.

15. The curable resin composition according to claim 13, wherein the organosilicon compound has an aromatic ring structure.

16. The curable resin composition according to claim 13, wherein the reactive site-containing organosilicon compound is contained in an amount of 90 parts by weight or more and 98 parts by weight or less in 100 parts by weight of an amount of resin solids in the curable resin composition.

17. The curable resin composition according to claim 11, containing a catalyst that promotes curing reaction.

18. The curable resin composition according to claim 13, containing a polyfunctional crosslinking agent capable of reacting with a reactive site of the reactive site-containing organosilicon compound.

19. A method for producing a stack, comprising the steps of: forming an organic film on a surface of a first substrate having an electrode, the surface being a surface on which the electrode is formed; forming a through-hole in the organic film; filling the through-hole with a conductive material; forming a bonding electrode by polishing the surface of the substrate on the side where the through-hole is filled with the conductive material; and bonding the first substrate on which the bonding electrode is formed and a second substrate on which the bonding electrode is formed such that the bonding electrodes are bonded to each other.

20. A method for producing a substrate having a bonding electrode, comprising the steps of: forming an organic film on a surface of a substrate having an electrode, the surface being a surface on which the electrode is formed; forming a through-hole in the organic film; filling the through-hole with a conductive material; and forming a bonding electrode by polishing the surface of the substrate.

21. A semiconductor device comprising the stack according to claim 1.

22. An imaging device comprising the stack according to claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0103] FIG. 1 is a schematic view of an embodiment of the stack of the present invention.

[0104] FIG. 2 is a schematic view of an embodiment of the stack of the present invention.

DESCRIPTION OF EMBODIMENTS

[0105] Embodiments of the present invention are more specifically described in the following with reference to examples. The present invention, however, is not limited to these examples.

(Production of Curable Resin)

(1) Production of POSS-A

[0106] A reaction vessel equipped with a reflux condenser, a thermometer, and a dropping funnel was charged with 320 g of phenyltrimethoxysilane (produced by Tokyo Chemical Industry Co., Ltd., molecular weight 198.29), 8.8 g of sodium hydroxide, 6.6 g of water, and 263 mL of 2-propanol. Heating was started under a nitrogen gas flow with stirring. Stirring was continued for six hours from the start of reflux, and the mixture was then left to stand overnight at room temperature. The reaction mixture was transferred into a filter and filtered by pressurization with nitrogen gas. The obtained solid was washed with 2-propyl alcohol once, filtered, and then dried at 80° C. under reduced pressure to give 330 g of a colorless solid (DD-ONa).

[0107] Next, a reaction vessel equipped with a reflux condenser, a thermometer, and a dropping funnel was charged with 20 g of cyclopentyl methyl ether, 2.4 g of 2-propanol, 14 g of ion-exchanged water, and 7.25 g of dichloromethylsilane (produced by Tokyo Chemical Industry Co., Ltd., molecular weight 115.03). They were stirred in a nitrogen atmosphere at room temperature. Subsequently, 8 g of the compound (DD-ONa) obtained above and 20 g of cyclopentyl methyl ether were put into the dropping funnel, made into a slurry, and added dropwise into the reactor over 30 minutes. Stirring was continued for 30 minutes after the termination of the dropwise addition. After the reaction, stirring was terminated, and the mixture was left to stand to separate it into an organic phase and an aqueous phase. The organic phase was neutralized by washing with water, filtered through a membrane filter to remove impurities, and concentrated under reduced pressure at 60° C. using a rotary evaporator to give a 9.5 g of a colorless solid. This colorless solid was washed with 10 g of methyl acetate and dried under reduced pressure to give 6.2 g of a colorless, powdery solid (DD(Me)-OH).

[0108] A 100-mL flask was equipped with a condenser, a mechanical stirrer, a Dean-Stark apparatus, an oil bath, and a thermometer protecting tube. The air inside the flask was purged with nitrogen. The flask was charged with 5.0 g of the DD(Me)-OH, 2.5 g of octamethylcyclotetrasiloxane (D4), 0.5 g of RCP-160M (strongly acidic cation exchange resin, produced by Mitsubishi Chemical Corporation, water content 23.4 mass %), and 51.0 mL of dehydrated toluene. The mixture was refluxed for one hour to recover 22.4 mL of toluene and 0.12 g of water contained in an amount of 23.4 mass % in the RCP-160M. After reflux, the temperature was cooled to 80° C., and 0.55 g of pure water was added, followed by aging at 80° C. The equilibrium was reached after five hours. After cooling to room temperature, RCP-160M was filtered out, and the obtained filtrate was washed with water once. The solvent and low-boiling components of the filtrate were then distilled off. The obtained crude product was re-precipitated in heptane for refinement, whereby an organosilicon compound (POSS-A, weight average molecular weight 130,000) having a structure of the following formula (7) wherein m2 is 55 and the average of n2 is 4 was obtained.

##STR00008##

(2) Production of POSS-B

[0109] An organosilicon compound (POSS-B, weight average molecular weight 130,000) having a structure of the formula (2) wherein m2 is 38 and the average of n2 is 8 was obtained as in the production of POSS-A, except that the amount of octamethylcyclotetrasiloxane added was 5.0 g.

(3) Production of POSS-C

[0110] An organosilicon compound (POSS-C, weight average molecular weight 90,000) having a structure of the formula (2) wherein m2 is 50 and the average of n2 is 2 was obtained as in the production of POSS-A, except that the amount of octamethylcyclotetrasiloxane added was 1.5 g.

(4) Production of POSS-D

[0111] An organosilicon compound (POSS-D, weight average molecular weight 110,000) having a structure of the following formula (8) wherein m2 is 60 and the average of n2 is 4 was obtained as in the production of POSS-A, except that phenyltrimethoxysilane was changed to methyltrimethoxysilane (produced by Tokyo Chemical Industry Co., Ltd., molecular weight 136.22) and the amount of methyltrimethoxysilane added was 210 g.

##STR00009##

(5) POSS-E

[0112] SR-13 produced by Konishi Chemical Ind. Co., Ltd. was used. SR-13 is a silsesquioxane compound that does not satisfy the formula (1).

(6) POSS-F

[0113] SR-33 produced by Konishi Chemical Ind. Co., Ltd. was used. SR-33 is silsesquioxane having an aromatic ring group and not satisfying the formula (1).

(7) PDMS resin

[0114] KR-255 produced by Shin-Etsu Chemical Co., Ltd. was used as a PDMS resin.

(8) Production of wafer 1

[0115] Films of SiO (500 nm), SiCN (50 nm), and SiO (250 nm) were sequentially formed on a 12-inch silicon wafer by plasma CVD. The SiO layer (250 nm) as the front layer was etched using a photomask. Subsequently, a Ta layer (50 nm) was formed and a TaN (10 nm) layer was further formed thereon, whereby barrier metal layers were formed. This was followed by Cu plating and planarization by CMP to form an electrode pattern. On the electrode pattern was formed a SiCN layer (50 nm) and a SiO layer (500 nm) by plasma CVD, whereby a wafer 1 having electrodes were obtained.

(9) Production of wafer 2

[0116] A wafer 2 was produced as in the production of the wafer 1, except that the wafer 2 was patterned such that the opposing bonding electrodes and the electrodes formed on the wafers would form daisy chains when the wafers were bonded.

Example 1

[0117] A hundred parts by weight of the obtained POSS-A, 0.1 parts by weight of dibutyltin dilaurate as a catalyst, and 1 part by weight of silicate MS51 (produced by Mitsubishi Chemical Corporation) as a crosslinking agent were dissolved in propylene glycol monoethyl acetate and mixed such that the amount of resin solids was 50%, whereby a curable resin composition solution was obtained.

[0118] Subsequently, the obtained curable resin composition solution was applied, with a spin coater, to the surface of the wafer 1 on which the electrodes were formed, heated at 70° C. for 30 minutes and then at 90° C. for one hour to evaporate off the solvent, and further heated at 200° C. for one hour to form an organic film having a thickness of 20 μm on the electrode surface of the wafer 1. A SiN layer (500 nm) was then formed by plasma CVD. Subsequently, the SiN layer and the organic film as well as the SiO layer (500 nm) and the SiCN layer (50 nm) on the electrode surface of the wafer 1 were etched using a photomask to form through-holes on the electrodes of the wafer 1. Here, the diameter of the etched vias was 20 μm, and the pitch between adjacent vias was 40 μm. Subsequently, a Ta layer (50 nm) was formed and a TaN layer (10 nm) was further formed thereon, whereby barrier metal layers were formed. Cu plating was then performed to fill the through-holes with a conductive material. Subsequently, the surface of the wafer 1 on the Cu-plated side (the surface of the wafer 1 on the side where the organic film was stacked) was polished to remove unnecessary portions of the barrier layers and the conductive material, whereby bonding electrodes were formed.

[0119] Separately, an organic film and bonding electrodes were formed also on the wafer 2 as in the production of the wafer 1, except that the wafer 2 was patterned such that the opposing electrodes would form daisy chains.

[0120] The wafer 1 and wafer 2 were then subjected to H.sub.2 plasma cleaning, and the two substrates were bonded in vacuum such that the bonding electrodes were superimposed on each other. The substrates were heat-treated at 400° C. for four hours, whereby a stack was obtained.

Examples 2 to 8

[0121] A stack was obtained as in Example 1, except that the type of the curable resin and the presence or absence of the catalyst were as shown in Table 1.

Example 9

[0122] A stack was obtained as in Example 5, except that the amount of silicate MS51 (produced by Mitsubishi Chemical Corporation) as a crosslinking agent was 3.2 parts by weight.

Example 10

[0123] A stack was obtained as in Example 5, except that the amount of silicate MS51 (produced by Mitsubishi Chemical Corporation) as a crosslinking agent was 16 parts by weight.

Example 11

[0124] A stack was obtained as in Example 5, except that the amount of silicate MS51 (produced by Mitsubishi Chemical Corporation) as a crosslinking agent was 32 parts by weight.

Example 12

[0125] A stack was obtained as in Example 1, except that no SiN layer (500 nm) was formed after the organic films were formed.

Comparative Example 1

[0126] A stack was obtained as in Example 1, except that an inorganic layer (20 μm) made of Si.sub.3N.sub.4 was formed by plasma CVD on the surface of the wafer 1 on which the electrodes were formed, and that the inorganic layer was used as a substitute for the organic film. The specific conditions for plasma CVD were as follows.

Raw material gas: SiH.sub.4 gas and nitrogen gas
Flow rate: SiH.sub.4 gas 10 sccm, nitrogen gas 200 sccm
RF power: 10 W (frequency 2.45 GHz)
Temperature inside chamber: 100° C.
Pressure inside chamber: 0.9 Torr

Comparative Example 2

[0127] A stack was obtained as in Comparative Example 1 except that SiH.sub.4 gas and oxygen gas were used as raw material gases, and that the plasma CVD target was changed to SiO.sub.2 to form an inorganic layer (20 μm) made of SiO.sub.2.

(Measurement of Weight Loss)

[0128] Single layers of organic films and single layers of inorganic layers were produced by the above methods. The obtained single layers were each heated using a thermogravimetry-differential thermal analyzer (TG-DTA: STA7200, produced by Hitachi High-Tech Science Corporation) under a nitrogen flow (50 mL/min) from 25° C. to 400° C. at a heating rate of 10° C./min, and the weight loss when the single layer was held at 400° C. for four hours was measured. Table 1 shows the results.

(Measurement of Surface Hardness)

[0129] A side surface of each of the obtained stacks was embedded in a cold mounting resin, and the resin was ground to expose the organic films or the inorganic layers at the side surface. The measurement was then performed under the conditions that the sample is indented to 1,000 nm using a nanoindenter (TI 950 TriboIndenter produced by Scienta Omicron, Inc.) at a rate of 200 nm measured displacement/sec and then the measurement probe is pulled out at a rate of 200 nm/sec. Thus, an indentation curve for the organic films or the inorganic layers was obtained. The measurement probe used was a Berkovich diamond indenter. From the obtained indentation curve, the surface nanoindentation hardness was calculated in conformity with ISO14577, whereby the surface hardness was determined. The constant s related to the indenter shape was 0.75 (s=0.75). Table 1 shows the results.

(Evaluation of Tensile Modulus of Elasticity)

[0130] Single layers of organic films and single layers of inorganic layers were produced by the above methods. The tensile modulus of elasticity of each of the obtained single layers was measured under the conditions of a constant-rate heating tensile mode, a heating rate of 10° C./min, and a frequency of 10 Hz using a dynamic viscoelastic analyzer (DVA-200 produced by IT Measurement Co., Ltd.).

<Evaluation>

[0131] The stacks obtained in the examples and the comparative examples were evaluated as follows. Table 1 shows the results.

(Evaluation of Connection Reliability)

[0132] In each of the stacks obtained in the examples and the comparative examples, electrodes located at a wafer center portion, 5 cm away from the wafer center, and 10 cm away from the wafer center were examined for the current conduction. The initial connection reliability was evaluated in accordance with the following criteria. The electrodes at each of the locations formed a daisy chain consisting of 10×10 electrodes.

∘ (Good): There was conduction at all the locations after the bonding of the wafers.
× (Poor): There was conduction failure at some of the locations after the bonding of the wafers.

[0133] Subsequently, the stack was left to stand at −40° C. for 30 minutes, subsequently heated to 125° C., and left to stand for 30 minutes. These operations were defined as one set, and 100 sets or 300 sets were performed (reliability test). Thereafter, the same evaluation as for the initial connection reliability was performed to evaluate the connection reliability after reliability test

∘∘ (Excellent): There was conduction at all the locations after 300 sets.
∘ (Good): There was conduction at all the locations after 100 sets, but there was conduction failure at some of the locations after 300 sets.
× (Poor): There was conduction failure at some of the locations after 100 sets.

(Evaluation of Adhesion Reliability)

[0134] The delamination area of electrode portions located at a wafer center portion, 5 cm away from the wafer center, and 10 cm away from the wafer center was measured using an ultrasonic imaging device. Based on the obtained delamination area, the adhesion reliability was evaluated in accordance with the following criteria. This evaluation was performed for each of the stack before the reliability test (initial) and the stack after the reliability test (100 sets).

∘∘ (Excellent): The delamination area was less than 5%.
∘ (Good): The delamination area was 5% or greater and less than 30%.
× (Poor): The delamination area was 30% or greater.

TABLE-US-00001 TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 Curable POSS-A POSS-A POSS-B POSS-C POSS-D POSS-E POSS-F PDMS resin resin Cosslinking 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 agent Catalyst 1.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 Weight 3.0 5.0 >5.0  4.0 4.0 >5.0  >5.0  >10.0  loss (%) Surface 0.5 0.3 0.3 0.8 0.9 0.8 0.3 0.2 hardness (Gpa) Tensile 0.4 0.3 0.2 0.5 0.7 0.5 0.4 0.2 modulus of elasticity (GPa) Inorganic Present Present Present Present Present Present Present Present layer Connection Initial ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ reliability After ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ reliability test Adhesion Initial ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘ reliability After ∘∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ reliability test Compar- Compar- ative ative Exam- Exam- Exam- Exam- Exam- Exam- ple 9 ple 10 ple 11 ple 12 ple 1 ple 2 Curable POSS-D POSS-D POSS-D POSS-A Si.sub.3N.sub.4 SiO.sub.2 resin Cosslinking 3.2 16.0  32.0  1.0 — — agent Catalyst 1.0 1.0 1.0 1.0 — — Weight 4.0 6.0 8.0 3.0 0.0 0.0 loss (%) Surface 0.9 0.5 0.5 0.5 9.8 14.0  hardness (Gpa) Tensile 0.9 0.6 0.6 0.4 70.0  290.0  modulus of elasticity (GPa) Inorganic Present Present Present Absent Present Present layer Connection Initial ∘ ∘ ∘ ∘ ∘ ∘ reliability After ∘∘ ∘∘ ∘∘ ∘ x x reliability test Adhesion Initial ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ ∘∘ reliability After ∘ ∘ ∘ ∘ x x reliability test

INDUSTRIAL APPLICABILITY

[0135] The present invention can provide a stack having high electrical connection reliability, a curable resin composition used for the stack, a method for producing the stack, a method for producing a substrate having a bonding electrode used for producing the stack, a semiconductor device including the stack, and an imaging device including the stack.

REFERENCE SIGNS LIST

[0136] 1 first substrate [0137] 2 second substrate [0138] 3 electrode [0139] 4 organic film [0140] 5 through-hole [0141] 6 inorganic layer [0142] 7 barrier metal layer