JPH09246328A - Diamond coated bonding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bonding tool having high adhesive strength with a polycrystalline diamond coated substrate and excellent durability. SOLUTION: This bonding tool is composed of a substrate, which is mainly composed of SiC, and a diamond-coated substrate, consisting of a polycrystalline diamond coated film formed in orientation mainly to substrate surface which are soldered to the tip of the tool, and a sintered body has a porosity of 5 to 35%. It is desirable that this bonding tool consists of the first diamond layer of 5 to 10μm in thickness containing amorphous carbon where polycrystalline diamond film is brought into contact with a substrate, and the second diamond layer of 10 to 200μm in thickness and having substantially 100% purity and laminated on the first diamond layer in orientation to (100) surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TAB (Tape Automated Bonding) bonding tool used in a semiconductor chip manufacturing process. More specifically, it relates to a bonding tool having a polycrystalline diamond coating formed on its tip.

[0002]

2. Description of the Related Art In recent years, technological progress in the semiconductor field has been remarkable,
The production of applied products using IC, LSI, etc. is increasing year by year. In order to bring out the electrical characteristics of these semiconductor elements, it is necessary to connect the leads wired on the tape to the semiconductor elements. For this connection, a method in which a lead bonding portion is pressed by a heated bonding tool and thermocompression bonding is widely adopted. An extremely smooth and high hardness single crystal diamond is used at the tip of this bonding tool because it has high durability because it does not remain after thermocompression bonding. However, since single crystal diamond is expensive and only an area of several mm square at most can be obtained, it is not possible to thermocompression bond a larger area joint at a time.

In order to solve this point, in recent years, a bonding tool has been proposed in which polycrystalline diamond is deposited on the tip by a vapor phase synthesis method (CVD method) (Japanese Patent Laid-Open No. HEI-2).
-224349). In this bonding tool, polycrystalline diamond deposited by a CVD method on a substrate made of a sintered body containing Si or any one of Si ₃ N ₄ , SiC, and AlN as a main component or a composite body of these is used in the thickness direction (100 ) Plane or (110) plane oriented tool tip is brazed to the metal base material of the tool.

[0004]

CVD on the surface of the substrate
When actually bonding with a bonding tool formed by brazing the tool tip made of the above-mentioned sintered body or composite in which a polycrystalline diamond film is deposited by the method to the metal base material of the tool, usually the tool tip and The metal base material of the tool is kept at the high temperature necessary for joining, but the tip of the tool is suddenly cooled and subjected to thermal shock during lead joining. In such a case, if the SiC sintered body used for the substrate is dense, the thermal conductivity is better than that of the porous sintered body, so that the brazed portion is also subjected to thermal shock due to the temperature decrease. If this becomes a large area type bonding tool typified by the bonding of ICs for electronic liquid crystal displays, it will be greatly affected by this thermal shock, and if the bonding accuracy of the brazing bonding part is reduced or if it is severe, the tool metal Problems such as the dropping of the substrate from the base material occur. If the SiC sintered body used for the above-mentioned substrate is dense, the surface of the substrate is too smooth as compared with the porous sintered body, and the adhesion strength of the polycrystalline diamond coating to the substrate is not sufficiently high, so that the above-mentioned thermal shock may occur. If it is received, problems such as damage and peeling of the coating occur relatively easily.

An object of the present invention is to provide a diamond-coated bonding tool having a higher adhesion strength of a polycrystalline diamond coating to a substrate and excellent durability.

[0006]

The invention according to claim 1 is
A diamond-coated base consisting of a sintered body containing SiC as a main component and a polycrystalline diamond coating formed mainly on the surface of the base with a (110) orientation is brazed to the tool tip. The diamond-coated bonding tool according to claim 1, wherein the sintered body has a porosity of 5 to 35%. In the present specification, "porosity" means the ratio of the volume of pores contained in the sintered body to the total volume,
The "pores" include not only closed pores that are closed but also open pores that communicate with the outside air.

The invention according to claim 2 is the invention according to claim 1, wherein the first diamond layer having a thickness of 0.5 to 10 μm and containing amorphous carbon in which the polycrystalline diamond film is in contact with the substrate, and the diamond layer. A diamond coated bonding tool according to claim 1 which comprises a substantially 100% pure second diamond layer having a thickness of 10 to 200 µm and oriented in the (110) plane.

The SiC sintered body having a porosity of 5 to 35%, which is the substrate of the present invention, has a characteristic that the thermal conductivity is lower than that of a dense SiC sintered body, and the surface thereof has open pores or the like. , Covered with fine irregularities. In addition, 0.
Since the first diamond layer having a thickness of 5 to 10 μm contains amorphous carbon, its thermal conductivity is lower than that of the second diamond layer. When a polycrystalline diamond coating is formed on the surface of the sintered body, a part of this coating penetrates into fine irregularities, and the polycrystalline diamond coating is anchored in these irregularities. For this reason, the polycrystalline diamond film is more surely adhered to the sintered body, which is the base, with high strength. By forming the polycrystalline diamond film with the (110) plane oriented, the wear resistance and the welding resistance are excellent, and the workability is good.

In the bonding tool of the present invention, when the tip of the tool held at a high temperature is thermally shocked by the low temperature lead at the time of joining the leads, the thermal conductivity of the substrate is low, so that the tool brazing layer and the tool are The metal base material is less susceptible to temperature changes and thermal shock is mitigated. In the case of having the first diamond layer, the thermal shock is further mitigated. Further, in the bonding tool of the present invention, when the tool tip is subjected to compressive stress due to thermocompression bonding, the polycrystalline diamond coating does not peel off from the substrate due to the high adhesion strength of the polycrystalline diamond coating to the substrate. When the first diamond layer is provided, the compressive stress is relieved, and the peeling phenomenon is further suppressed. As a result, the cracking phenomenon that occurs in the base and the coating due to the difference in the coefficient of thermal expansion between the base and the brazing layer and the metal base material of the tool or the insufficient adhesion between the coating and the base, and the brazing of the base The phenomenon of separation from the layer or coating disappears.

If the porosity of the substrate is less than 5%, the above-mentioned effects are not exhibited, and if the porosity exceeds 35%, the strength of the sintered body is lowered and the durability of the bonding tool is deteriorated. The porosity is preferably 15 to 35%. Also the first
If the thickness of the diamond layer is less than 0.5 μm, the effect does not appear, and if it exceeds 10 μm, the strength and wear resistance of the entire coating deteriorate. Furthermore, the thickness of the second diamond layer is 10 μm
If it is less than 3, cracking is likely to occur during polishing of the coated surface or during use as a tool. Further, when it exceeds 200 μm, it takes too long to form it, and even when it is 200 μm or more, its effect is almost unchanged.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The bonding tool of the present invention is 400 to 700 when the tool is manufactured and used.
Since the sintered body of the present invention is exposed to a high temperature of about ° C, it is necessary that the coefficient of thermal expansion be close to that of diamond and have heat resistance. Therefore, SiC is selected for the sintered body of the present invention. This sintered body is not limited to one made of 100% SiC, but one having SiC as a main component, such as Si.
Including those in which C is 95% by weight or more. The sintered body is formed into a required shape and becomes a base.

A polycrystalline diamond film is formed on the surface of the sintered body, which is the base, by the CVD method. In order to polish the coated surface at the time of making a tool and to facilitate its workability, polycrystalline diamond is synthesized so as to be oriented mainly in the (110) plane in the thickness direction. This orientation ratio is 50% or more of the coated surface. When the (110) plane orientation ratio of the coated surface is 50% or less, an appropriate machined surface cannot be obtained and the machinability deteriorates. As described above, in order to improve the adhesion with the sintered body, the first diamond layer containing amorphous carbon is synthesized in the initial stage of the synthesis, and the outer surface layer has 10 layers.
It is also possible to form a 0% pure second diamond layer. A diamond-coated substrate composed of a sintered body and a polycrystalline diamond coating is joined to the tip of a tool as a base material by brazing. After synthesizing a polycrystalline diamond coating by the CVD method or brazing a diamond-coated substrate, the coating surface is polished to obtain a surface roughness (Rma
x) is 0.1 μm or less, which is comparable to that of single crystal diamond.

[0013]

Next, examples of the present invention will be described together with comparative examples. The present invention is not limited to the embodiments described below. <Examples 1 to 11> S is obtained by sintering SiC powder.
A sintered body containing iC as a main component was produced. That is, 1% by weight of B (boron) powder as a sintering aid was added to SiC powder and mixed uniformly. This mixed powder was press-molded by a predetermined mold so that the density was 50 to 60% of the theoretical density. Eleven compacts were obtained under the same conditions. Sintered under the six conditions shown in Table 1 below, vertical 10 mm, width 5 mm, thickness 2 mm
A sintered body as a base of was obtained.

[0014]

[Table 1]

The surface of the sintered body was polished with a # 270 diamond grindstone to flatten the surface roughness to about 3 μm in Rmax. Of these 11 sintered bodies, 6 are hot filament CVD methods and 5 are microwave plasma CVs.
The surface of each sintered body was coated with diamond by method D.
Upon coating with diamond, the sintered body as a base was fixed on a support made of quartz glass. Hot filament CVD
The diamond coating by the method uses a Ta wire with a diameter of 0.4 mm as a filament and a filament temperature of 2150
C., pressure 30 Torr, and substrate temperature 900.degree. In the diamond coating by the microwave plasma CVD method, the flow rate of the source gas H ₂ is 200 cc / min, C
The flow rate of H ₄ was 4 cc / min, the flow rate of Ar was 50 cc / min, and the microwave oscillator output was 800 W at a pressure of 100 Torr. In the hot filament CVD method and the microwave plasma CVD method, that is, in Example 2, Example 5, Example 8 and Example 11, the amorphous carbon of the invention according to claim 2 of the present invention is applied to the surface of each sintered body. First including
A diamond layer is formed and 10 is formed on this diamond layer.
A second diamond layer of 0% pure was deposited.

Comparative Example 1 A mixed powder containing SiC powder as a main component was prepared in the same manner as in Example 1, and this mixed powder was hot-press molded by a predetermined mold so that the density was 90% or more of the theoretical density. did. This high-density molded product was sintered under the condition G shown in Table 2 below and the same as in Example 1 with a vertical length of 10 mm and a width of 5.
A sintered body having a thickness of 2 mm and a thickness of 2 mm was obtained. The surface of this sintered body was polished in the same manner as in Example 1 to obtain a surface roughness of Rmax of about 3 μm.
It was flattened to about m. A polycrystalline diamond film was formed on the surface of this sintered body by the microwave plasma CVD method under the same conditions as in Example 7.

[0017]

[Table 2]

Comparative Example 2 A mixed powder was prepared in the same manner as in Example 1 except that Ta powder was used instead of SiC powder. The mixed powder was molded under the same conditions as in Comparative Example 1 and sintered to obtain a sintered body having the same shape and size as Comparative Example 1. The surface of this sintered body was polished in the same manner as in Example 1 to obtain a surface roughness of Rmax of about 3 μm.
It was flattened to some extent. A polycrystalline diamond film was formed on the surface of this sintered body by the microwave plasma CVD method under the same conditions as in Example 7.

Comparative Example 3 A mixed powder was prepared in the same manner as in Example 1 except that Mo powder was used instead of SiC powder. The mixed powder was molded under the same conditions as in Comparative Example 1 and sintered to obtain a sintered body having the same shape and size as Comparative Example 1. The surface of this sintered body was polished in the same manner as in Example 1 to obtain a surface roughness of Rmax of about 3 μm.
It was flattened to some extent. A polycrystalline diamond film was formed on the surface of this sintered body by the microwave plasma CVD method under the same conditions as in Example 7.

<Comparative Example 4> A mixed powder was prepared in the same manner as in Example 1 except that W powder was used instead of SiC powder. The mixed powder was molded under the same conditions as in Comparative Example 1 and sintered to obtain a sintered body having the same shape and size as Comparative Example 1. The surface of this sintered body was polished in the same manner as in Example 1 to flatten the surface roughness to Rmax of about 3 μm. On the surface of this sintered body, a hot filament CV
A polycrystalline diamond film was formed by the method D under the same conditions as in Example 1.

<Comparative Example 5> Si ₃ instead of SiC powder
A mixed powder was prepared in the same manner as in Example 1 using N ₄ powder. The mixed powder was molded under the same conditions as in Comparative Example 1 and sintered to obtain a sintered body having the same shape and size as Comparative Example 1. A polycrystalline diamond film was formed on the surface of this sintered body by the hot filament CVD method under the same conditions as in Example 1.

<Measurement Results of Porosity and Crystal Orientation of Diamond Coating Surface> In Examples 1 to 11 and Comparative Examples 1 to 5, the actual porosity of the sintered body before forming the polycrystalline diamond coating was measured by porosimeter. Method, density measurement, and microscopic observation of the surface. Moreover, the polycrystalline diamond synthesized by each CVD method was analyzed by X-ray diffraction (220).
Intensity ratio of the peaks of the (111) plane and the (220) / (11) plane
1) was obtained, and the orientation of the (110) plane was examined from this value. Table 3 shows the results.

[0023]

[Table 3]

<Heat Cycling Test> The diamond-coated substrates obtained in Examples 1 to 11 and Comparative Examples 1 to 5 were each held in air at 200 ° C. for 15 seconds and then at 600 ° C. at a rate of 40 ° C./second. The temperature was raised to and held at 600 ° C. for 10 seconds. Then, the temperature was lowered to 200 ° C at a rate of 5 ° C / sec. Repeat the heating and cooling between 200 and 600 ℃ 1
It was performed 00 times. The number of times when the diamond coating had an abnormality up to 100 times was counted. The results are shown in Table 4.

<Durability Test> Examples 1 to 11 and Comparative Example 1
Ti on the back surface of the substrate of the diamond-coated substrate obtained in
Was vapor-deposited to a thickness of 3 μm to form a metallized layer, the metallized layer was brought into contact with the tip of a stainless shank material via a commercially available brazing material, and vacuum brazing was performed. The diamond surface of the diamond-coated substrate brazed to the shank material was polished with a diamond electrodeposition grindstone of mesh size # 200. The roughness Rmax of the diamond surface of all the substrates was 0.1 μm or less. A durability test of the bonding tool thus obtained was conducted. Durability test, the tool tip temperature is 600 ℃, the crimping time is 3 seconds,
The tape on which the leads were wired was repeatedly bonded 1 million times, and the degree of damage to the diamond coating and the brazed portion was visually observed. Table 4 shows the results.
Shown in

[0026]

[Table 4]

As is clear from Table 4, in Comparative Examples 1 to 5 in the heat cycle test, the diamond coating peeled off after 15 to 80 times, while in Examples 1 to 11, there was no damage at all. Further, in the durability test, in Comparative Examples 1 to 5, falling of the brazed portion and peeling damage of the diamond film were observed, while in Examples 1 to 11, there was no damage or wear at all even after 1 million tests. It was In particular, as is clear from Table 3, in Comparative Example 1 and Comparative Example 5, the porosity is 1% or less even though the orientation of the (110) plane of the polycrystalline diamond film is as excellent as that of the example. Therefore, as described above, the thermal and mechanical durability was inferior to that of Examples 1 to 11.

[0028]

As described above, according to the present invention, it is possible to obtain a bonding tool having a higher adhesion strength of the polycrystalline diamond film to the substrate and excellent durability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minor Kojima 5-7-12 Omorikita, Ota-ku, Tokyo Ogura Gem Seiki Co., Ltd. (72) Inventor Hiromi Umezawa 5-7 Omorikita, Ota-ku, Tokyo No. 12 Ogura Gem Seiki Co., Ltd.

Claims (2)

[Claims] 1. A tool tip portion of a diamond-coated base material comprising a base body made of a sintered body containing SiC as a main component, and a polycrystalline diamond coating film formed on the surface of the base body mainly oriented in the (110) plane. A diamond-coated bonding tool obtained by brazing, wherein the sintered body has a porosity of 5 to 35%. 2. A first diamond layer having a thickness of 0.5 to 10 μm containing amorphous carbon which is in contact with a substrate, and a 10 to 200 μm thick layer of the polycrystalline diamond film oriented in the (110) plane on the diamond layer. The diamond coated bonding tool of claim 1 comprising a second diamond layer substantially 100% pure.