KR-20260066755-A - Alloy powder, alloy paste, and semiconductor device

Abstract

The present disclosure provides an alloy powder capable of forming a bonding layer with excellent bonding reliability, operating at high temperatures, and compliant with environmental regulations. The alloy powder of the present disclosure is characterized by having an AgSi eutectic structure, and by selecting one particle from an image of a particle cross-section captured by SEM at a magnification of 2,000 to 50,000 times, measuring the total outer circumference length and the length of the outer circumference where the eutectic structure exists, excluding a region where the eutectic structure does not exist at all in a region of 0.2 μm from the outer circumference toward the center of the particle, and calculating the ratio to the total outer circumference length as the ratio of the AgSi structure on the particle surface, and performing this method on any 10 adjacent particles, wherein the ratio of the AgSi eutectic structure is 10% or more in at least 8 of them.

Inventors

• 사카모토, 다케시
• 우에시마, 미노루
• 천, 촨퉁
• 나카야마, 고지
• 나오에, 다쿠야

Assignees

• 주식회사 다이셀
• 고꾸리쯔 다이가꾸 호우징 오사까 다이가꾸

Dates

Publication Date

20260512

Application Date

20240903

Priority Date

20230908

Claims (8)

1. Having an AgSi process structure, An alloy powder comprising: selecting one particle from an image of a particle cross-section captured by SEM at a magnification of 2,000 to 50,000 times; measuring the total outer circumference length and the length of the outer circumference where a eutectic structure exists, excluding a region where no eutectic structure exists at all in the region extending from the outer circumference to a depth of 0.2 μm in the direction of the center of the particle; and calculating the ratio to the total outer circumference length as the ratio of the AgSi structure on the particle surface, wherein the ratio of the AgSi eutectic structure is 10% or more in at least 8 of the particles.
2. The alloy powder according to claim 1, having an average particle size (median diameter) of 0.1 to 100 μm.
3. The alloy powder according to claim 1 or 2, wherein the silver (Ag) content relative to the total amount of the alloy powder is 15 to 97.6 mass% and the silicon (Si) content is 2.4 to 85 mass%.
4. An alloy paste comprising the alloy powder described in paragraph 1 or 2.
5. An alloy paste comprising the alloy powder described in paragraph 3.
6. In paragraph 4, an alloy paste additionally comprising organic material.
7. An alloy paste according to claim 4, further comprising metal particles other than the alloy powder, wherein the content of the metal particles other than the alloy powder is 5 to 2000 parts by mass per 100 parts by mass of the alloy powder.
8. A semiconductor device using the alloy paste described in paragraph 4 as a bonding layer for bonding a substrate and a workpiece.

Description

Alloy powder, alloy paste, and semiconductor device The present disclosure relates to alloy powder, alloy paste, and semiconductor devices. Additionally, the present application claims priority to Japanese Patent Application No. 2023-146495 filed on September 8, 2023, and incorporates the contents thereof herein by reference. Semiconductors used for power devices require high efficiency, low loss, and high-frequency switching, and the use of wide-gap semiconductors such as SiC and GaN is expanding. In these semiconductors, the operating temperature may exceed 200°C, and the bonding materials used for bonding needed to maintain high bonding reliability even during operation in the high-temperature region of the semiconductor or in harsh temperature cycle environments. In addition, solder has conventionally been used as a high-temperature bonding material, but due to stricter environmental regulations and safety concerns, lead-free materials have become necessary. As lead-free materials to replace such solder, for example, the materials of Patent Documents 1 to 3 have been known. Figure 1 is an SEM image of a cross-section of the alloy powder of the present disclosure. Figure 2 is an SEM image of a cross-section of the alloy powder of the present disclosure. FIG. 3 is a cross-sectional view schematically illustrating an example of an embodiment of a semiconductor device of the present disclosure. [Alloy Powder] An alloy powder of one embodiment of the present disclosure has an AgSi eutectic structure, and a method is performed on any 10 adjacent particles in which one particle is selected from an image of a particle cross-section captured by SEM at a magnification of 2,000 to 50,000 times, the length of the entire outer circumference and the length of the outer circumference where the eutectic structure exists, excluding a region where the eutectic structure does not exist at all in a region from the outer circumference to a depth of 0.2 μm in the direction of the center of the particle, and the ratio to the total outer circumference length is calculated as the ratio of the AgSi structure on the particle surface, and in at least 8 of them, the ratio of the AgSi eutectic structure is 10% or more. As for the alloy powder, only one type may be used, or two or more types may be used in combination. Figures 1 and 2 are magnified SEM images of cross-sections of the particles of the alloy powder. The black areas in the images are regions containing silicon (Si), and the white areas are regions containing an AgSi eutectic structure in which silicon (Si) is dispersed in Ag. In addition, in the present disclosure, the term "eutectic structure" refers to a structure characteristic of a eutectic alloy, in which two types of crystal phases simultaneously crystallize from a liquid phase at a specific temperature to form a very fine metallic structure. At this time, the eutectic structure is formed with a constant compositional ratio, and if the compositional ratio is off, one type of crystal precipitates first and generally grows coarsely. In cases where the composition deviates from the ideal eutectic structure, the crystal that precipitates first and grows while cooling from the liquidus temperature to the eutectic temperature is called a primary crystal. For example, in an AgSi alloy, when Si is contained in excess of the composition of the ideal eutectic structure, Si precipitates as a primary crystal, and as the primary crystal of Si grows, a fine eutectic structure begins to form for the first time when the AgSi composition in the remaining liquid phase becomes the ideal composition. In alloy powder having an AgSi eutectic structure in excess of Si compared to the composition ratio of such eutectic, Si primary crystals of about a few micrometers are dispersed within the particles, and within the AgSi eutectic structure, Si is finely dispersed in Ag at a size of about 100 nm or less. In addition, in an AgSi alloy, when Ag is contained in excess of the composition of the ideal eutectic structure, Ag precipitates as a primary crystal, and as the primary crystal of Ag grows, a fine eutectic structure begins to form for the first time when the AgSi composition in the remaining liquid phase becomes the ideal composition. Although the size of the primary crystal varies depending on the particle size, crystals with a difference of several to more than 10 times are observed within a single particle, and among these, the one with the larger size can be identified as the primary crystal. The method for producing alloy powder having the above process structure is not particularly limited, but, for example, it can be produced by a method of finely pulverizing a mixture of silver (Ag) and silicon (Si) heated until it becomes liquid using a gas atomization method or a water atomization method. In addition, when the ratio of the AgSi eutectic structure on the particle surface is measured by the method described above, it is preferab