Adhesive for mounting flip chip for use in a method for producing a semiconductor device

Abstract

The present invention aims to provide a method for producing a semiconductor device, the method being capable of achieving high reliability by suppressing voids. The present invention also aims to provide a flip-chip mounting adhesive for use in the method for producing a semiconductor device. The present invention relates to a method for producing a semiconductor device, including: step 1 of positioning a semiconductor chip on a substrate via an adhesive, the semiconductor chip including bump electrodes each having an end made of solder; step 2 of heating the semiconductor chip at a temperature of the melting point of the solder or higher to solder and bond the bump electrodes of the semiconductor chip to an electrode portion of the substrate, and concurrently to temporarily attach the adhesive; and step 3 of removing voids by heating the adhesive under a pressurized atmosphere, wherein the adhesive has an activation energy ΔE of 100 kJ/mol or less, a reaction rate of 20% or less at 2 seconds at 260° C., and a reaction rate of 40% or less at 4 seconds at 260° C., as determined by differential scanning calorimetry and Ozawa method.

Claims

1. A flip-chip mounting adhesive for use in a method for producing a semiconductor device, comprising at least a thermosetting resin and a thermosetting agent, wherein the thermosetting resin is an epoxy resin, wherein the adhesive has an activation energy ΔE of 100 kJ/mol or less, a reaction rate of 20% or less at 2 seconds at 260° C., and a reaction rate of 40% or less at 4 seconds at 260° C., as determined by differential scanning calorimetry and Ozawa method, and wherein the method for producing a semiconductor device comprises: step 1 of positioning a semiconductor chip on a substrate via the adhesive, the semiconductor chip including bump electrodes each having an end made of solder; step 2 of heating the semiconductor chip at a temperature of the melting point of the solder or higher to solder and bond the bump electrodes of the semiconductor chip to an electrode portion of the substrate, and concurrently to temporarily attach the adhesive; and step 3 of removing voids by heating the adhesive under a pressurized atmosphere.

2. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the adhesive further contains a curing accelerator.

3. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 2, wherein the curing accelerator is selected from the group consisting of imidazole curing accelerators and tertiary amine curing accelerators.

4. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 2, wherein the curing accelerator is present in an amount of between 0.5 and 50 parts by weight relative to 100 parts by weight of the thermosetting agent.

5. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the adhesive further contains an inorganic filler, and the amount of the inorganic filler is 60% by weight or less.

6. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the adhesive is a film-like adhesive.

7. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 6, further comprising a compound having an epoxy group, wherein the compound having an epoxy group has a weight average molecular weight of between 10000 and 1000000.

8. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 7, wherein the compound having an epoxy group is present in an amount of between 3 and 30% by weight.

9. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the epoxy resin has an epoxy equivalent weight of 160 or more.

10. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the epoxy resin is selected from the group consisting of bisphenol-type epoxy resins, novolak-type epoxy resins, resorcinol-type epoxy resins, aromatic epoxy resins, naphthalene-type epoxy resins, fluorene-type epoxy resins, cyclopentadiene-type epoxy resins, dicyclopentadiene-type epoxy resins, polyether-modified epoxy resins, NBR-modified epoxy resins, CTBN-modified epoxy resins, and hydrogenated products thereof.

11. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the thermosetting agent is selected from the group consisting of acid anhydride curing agents, phenolic curing agents, amine curing agents, latent curing agents, cationic catalyst-type curing agents, and mixtures thereof.

12. The flip-chip mounting adhesive for use in the method for producing a semiconductor device according to claim 1, wherein the thermosetting agent is present in an amount of between 60 and 110 equivalents relative to the total amount of epoxy groups in the adhesive.

Description

DESCRIPTION OF EMBODIMENTS

(1) Embodiments of the present invention are described in further detail below with reference to examples, but the present invention is not limited to these examples.

EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 to 5

(2) (1) Preparation of Adhesive

(3) The ingredients shown in Table 1 were added to MEK as a solvent in accordance with the blending ratio shown in Table 2, and these ingredients were mixed by stirring using a homodisper to prepare an adhesive solution. The thus-obtained adhesive solution was applied to a release PET film using an applicator to give a dried thickness of 30 μm and dried to prepare a film-like adhesive. The surface of the thus-obtained adhesive layer was protected with the release PET film (protection film) until use.

(4) (2) Differential Scanning Calorimetry and Ozawa Method

(5) Differential scanning calorimetry was carried out for the thus-obtained adhesive at four different heating rates of 1° C., 2° C., 5° C., and 10° C./min, and the reciprocal of the temperature T and the logarithm of the heating rate B (log B) were plotted. Then, the activation energy ΔE was calculated from the slope of the straight line obtained above, based on the above equation (1). Next, the reaction rate of the sample that was kept at 260° C. for 2 seconds, as well as at 260° C. for 4 seconds, was calculated from the activation energy ΔE, based on the above equation (2) for degradation at a constant temperature.

(6) Note that DSC6220 (available from SII NanoTechnology Inc.) and software for kinetics analysis (available from SII NanoTechnology Inc.) were used.

(7) (3) Production of Semiconductor Device

(8) (3-1) Step 1 of Positioning and Step 2 of Temporarily Attaching the Adhesive

(9) A semiconductor chip having bump electrodes each having an end made of solder (WALTS MB50-0101JY, melting point of the solder of 235° C., thickness of 100 μm, available from WALTS CO., LTD.), and a substrate having an Ni/Au electrode (WALTS-KIT MB50-0101JY available from WALTS CO., LTD.) were provided. A protection film on one side of the adhesive was peeled off, and the adhesive was adhered to the semiconductor chip at a stage temperature of 80° C. and a vacuum degree of 80 Pa, using a vacuum laminator (ATM-812M available from Takatori Corporation).

(10) Using a flip chip bonder (FC-3000S available from Toray Engineering Co., Ltd.), the semiconductor chip was positioned on the substrate via the adhesive (step 1), and the bonding stage temperature was set to 120° C. Under such conditions, the temperature was increased to 260° C. at a contact temperature of 160° C., and a pressure of 0.8 MPa was applied for 2 seconds to solder and bond the bump electrodes of the semiconductor chip to the electrode portion of the substrate, and concurrently to temporarily attach the adhesive (step 2).

(11) (3-2) Step 3 of Removing Voids

(12) The thus-obtained temporarily attached body was placed in a pressure oven (PCO-083TA available from NTT Advanced Technology Corporation) to heat the adhesive under a pressurized atmosphere under the following pressure and heating conditions so as to remove voids (step 3), and the adhesive was completely cured to obtain a semiconductor device.

(13) <Pressure and Heating Conditions>

(14) STEP 1: heating at a constant rate from 25° C. to 80° C. for 10 minutes, 0.5 MPa STEP 2: conditions maintained at 80° C. for 60 minutes, 0.5 MPa STEP 3: heating at a constant rate from 80° C. to 170° C., 0.5 MPa STEP 4: conditions maintained at 170° C. for 10 minutes, 0.5 MPa STEP 5: cooling from 170° C. to 25° C. over 30 minutes, 0.5 MPa STEP 6: cooling at a constant rate to room temperature over 60 minutes, 0.5 MPa
<Evaluation>

(15) The semiconductor devices obtained in the examples and the comparative examples were evaluated as follows. Table 2 shows the results.

(16) (1) Presence of Voids

(17) An ultrasonic inspection imaging device (C-SAM D9500 available from Nippon BARNES Company Ltd.) was used to observe voids in the semiconductor device before and after step 3 of removing voids and to evaluate the presence of voids. If the area where voids were present was less than 1% of the area of the semiconductor chip, it was regarded as “excellent (∘)”; if the area was 1% or more and less than 5%, it was regarded as “good (Δ)”; and if the area was 5% or more, it was regarded as “poor (×)”.

(18) (2) Electrode Bonding State

(19) The cross section of the semiconductor device was polished using a polisher, and the electrode bonding state of the bonded portion between the electrodes was observed using a microscope. If no adhesive was trapped between the upper and lower electrodes and the electrode bonding state was good, it was regarded as “excellent (∘)”; if the adhesive was slightly trapped between the upper and lower electrodes but the upper and the lower electrodes were bonded to each other, it was regarded as “good (Δ)”; and if the adhesive was trapped between the upper and lower electrodes and the upper and lower electrode were not bonded at all to each other, it was regarded as “poor (×)”.

(20) (3) Reliability Evaluation (TCT Test)

(21) A heating/cooling cycle test in a temperature range from −55° C. to 125° C. (30 minutes/cycle) was performed on the semiconductor device, and the value of conduction resistance was measured after every 100 cycles. When the value of conduction resistance changed by 5% or more from the initial value of conduction resistance prior to the heating/cooling cycle test, the semiconductor device was regarded as failing the test, and the number of cycles in which the rate of change in conduction resistance remained less than 5% from the initial value was counted for evaluation. If the number of cycles was 1000 or more, it was regarded as “excellent (∘)”; if the number of cycles was 300 or more and less than 1000, it was regarded as “good (Δ)”; and if the number of cycles was less than 300, it was regarded as “poor (×)”.

(22) TABLE-US-00001 TABLE 1 Epoxy equiv- alent Trade name Manufacturer Structure weight Thermo- HP-7200HH DIC Dicyclo- 280 setting pentadiene- resin type epoxy resin EXA-4850-150 DIC Bifunctional 450 epoxy resin EXA-830CRP DIC Bisphenol 160 F-type epoxy resin Thermo- YH-309 Mitsubishi Acid — setting Chemical anhydride agent Corporation YH-307 Mitsubishi Acid — Chemical anhydride Corporation Curing Fujicure-7000 T&K TOKA Liquid — acceler- imidazole ator compound 2MZA-PW SHIKOKU Imidazole — CHEMICALS compound CORPORATION 2MA-OK SHIKOKU Imidazole — CHEMICALS compound CORPORATION FXR-1121 SHIKOKU Imidazole — CHEMICALS compound CORPORATION High SG-P3 Nagase ChemteX Epoxy group- 4760  molecular Corporation containing weight acrylic compound polymer Inorganic SSP-01P Tokuyama Phenylsilane- — filler Corporation modified spherical silica Others W-5500 MITSUBISHI Acrylic — RAYON rubber CO., LTD. particles KBM-573 Shin-Etsu Silane — Chemical Co., coupling Ltd. agent

(23) TABLE-US-00002 TABLE 2 Example 1 Example 2 Example 3 Example 4 Example 5 Adhesive Thermosetting resin HP-7200HH 100  100  100  100  100  (parts by EXA-4850-150 20 20 20 20 — weight) EXA-830CRP — — — — 20 Thermosetting agent YH-309 60 60 60 60 — YH-307 — — — — 60 Curing accelerator Fujicure-7000   0.8  2  8 — — 2MZA-PW — — — — — 2MA-OK — — — — — FXR-1121 — — —  8  8 High molecular SG-P3 30 30 30 30 30 weight compound Inorganic filler SSP-01P 60 60 60 60 350 Others W-5500 20 20 20 20 20 KBM-573  2  2  2  2  2 Amount of inorganic filler 20 wt % 20 wt % 20 wt % 20 wt % 60 wt % Activation energy ΔE (kJ/mol) 70 72 77 86 91 Reaction rate at 2 seconds at 260° C.  8.3% 12.8% 19.1%  7.8% 16.8% Reaction rate at 4 seconds at 260° C. 15.2% 22.6% 38.9% 14.8% 39.8% Evaluation Presence of voids Before step 3 of removing voids X X X X X After step 3 of removing voids ◯ ◯ ◯ ◯ Δ Electrode bonding state ◯ ◯ ◯ ◯ Δ Reliability evaluation ◯ ◯ ◯ ◯ Δ Compara- Compara- Compara- Compara- Compara- tive tive tive tive tive Example 1 Example 2 Example 3 Example 4 Example 5 Adhesive Thermosetting resin HP-7200HH 100  100  100  100  100  (parts by EXA-4850-150 20 20 20 — — weight) EXA-830CRP — — — 20 20 Thermosetting agent YH-309 60 60 60 — — YH-307 — — — 60 60 Curing accelerator Fujicure-7000 16 — — — — 2MZA-PW — 8 — — — 2MA-OK — —  8  4 — FXR-1121 — — — —  8 High molecular SG-P3 30 30 30 30 30 weight compound Inorganic filler SSP-01P 60 60 60 400 400 Others W-5500 20 20 20 20 20 KBM-573  2  2  2  2  2 Amount of inorganic filler 20 wt % 20 wt % 20 wt % 63 wt % 63 wt % Activation energy ΔE (kJ/mol) 67 70 104  120  92 Reaction rate at 2 seconds at 260° C. 25.8% 42.5% 26.0% 11.5% 18.5% Reaction rate at 4 seconds at 260° C. 48.5% 75.4% 75.0% 38.6% 41.9% Evaluation Presence of voids Before step 3 of removing voids X X X X X After step 3 of removing voids X X X X Δ Electrode bonding state ◯ ◯ X Δ X Reliability evaluation X X X X X

INDUSTRIAL APPLICABILITY

(24) The present invention can provide a method for producing a semiconductor device, the method being capable of achieving high reliability by suppressing voids. The present invention can also provide a flip-chip mounting adhesive for use in the method for producing a semiconductor device.