JP2600336B2 - Method of manufacturing base material for high thermal conductive IC - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to a method for producing an IC substrate having a high thermal conductivity and a Cu layer on the surface of an AlN ceramic material which is an insulator. .

[Prior art and problems] AlN (aluminum nitride) ceramic material which has high thermal conductivity and is an insulator is promising for hybrid IC substrates and IC packages. For example, in order to apply this to an IC substrate, it is necessary to metallize the surface with low-resistance Cu as an electrode such as a wiring electrode and a wiring.

As a method of metallizing the surface of an AlN ceramic material, for example, the following method has conventionally been adopted. In this field, metallization means that a metal thin film is adhered to the surface of a ceramic material.

Since the AlN ceramic material has a property that it is difficult to wet with metal, the surface of the AlN ceramic substrate is oxidized at 1000
and l ₂ O _3, performs metallized etc. M _O -M _n method on the oxide layer.

Metallization is performed by evaporating Ti on an AlN ceramic substrate, and evaporating and heat-treating Pt and Au thereon. According to this method, the deposition strength is estimated to be about ² to 5 kg / mm ² , and this adhesion strength is provided by diffusion of active Ti into the AlN ceramic substrate.

The above method involves high-temperature processing at a temperature of 1000 ° C. or higher, which is expensive. In addition, it is expensive due to distortion and low yield.

In the above method, a heat treatment of Ti diffusion at 300 to 500 ° C. is required, and since soldering or brazing cannot be performed with Ti alone, a Pt layer or an Au layer is deposited thereon, which is expensive. Also
A between the AlN ceramic material and the conductive material deposited on it
Since a metal layer having a lower thermal conductivity than 1N is interposed, the above characteristics of AlN cannot be utilized.

[Means for Solving the Problem] The present invention provides a method of forming a Cu film on a surface of an AlN ceramic material by Cu vapor deposition.
While forming a layer, A is applied to the AlN ceramic material from the Cu layer surface.
Irradiation of 1 × 10 ¹⁵ to 1 × 10 ¹⁸ ions / cm ² is intended to obtain a Cu metallized layer having extremely high adhesion strength.

The metallizing method used in the present invention is disclosed in
Although disclosed in JP-A-91483, this is applied to an AlN ceramic material having high thermal conductivity and insulation to provide a substrate for IC utilizing the above characteristics.

 Hereinafter, embodiments of the present invention will be described.

 FIG. 3 shows a schematic diagram of an apparatus for practicing the present invention.

A bucket type ion source 4 is provided at a lower portion of the vacuum chamber 1, an electron beam heating type evaporation source 3 is provided at an intermediate portion, and a sample cooling type rotary sample holder 2 is provided at an upper portion. The bucket type ion source 4 includes a ground 5, a plasma electrode 6, a filament 8, an arc chamber 7, a gas inlet 9, and the like.

The gas ions are irradiated upward from the bucket type ion source 4, and the deposited metal is emitted upward from the electron beam heating type evaporation source 3, and both reach the rotary sample holder 2. An AlN ceramic material, which is an object of the present invention, is disposed on the holder.

The metal deposition and ion implantation on the surface of the ceramic material need not be performed all the time during metallization, but only during the initial formation of the mixing layer, the metal deposition and ion irradiation function at the same time. Metallization layer thickness required for brazing or maximizing brazing strength, typically up to a few microns, or both may function for all time during metallizing . However,
When the ion irradiation is performed, the metallized layer is sputtered by the ions, the growth of the metallized layer is suppressed, and the strength of the metallized layer may be deteriorated.

Using the apparatus shown in FIG.
The vapor deposition and Ar ion irradiation were performed simultaneously, and in the second stage, the film thickness was increased only by Cu vapor deposition.

Substrate: AlN Ion species: Ar Vacuum degree in chamber: 10 ^-6 Torr Acceleration energy: 5 to 25 keV Cu evaporated at an arbitrary speed is mixed with Ar ions accelerated at 5 to 25 eV on the AlN substrate surface. At that time, Cu atoms are sputtered or pushed into the inside by Ar ions, and a mixing layer is formed while repeating such mutual movement.

The thickness of the mixing layer was kept within a range where Ar ions could reach the substrate, and the thickness of the subsequent Cu vapor deposition layer was set at 5000 to 10000Å so that external conditions did not affect the mixing layer.

FIG. 1 is a conceptual view of a cross section of a surface layer of an AlN ceramic material formed by the above method. In the figure, a is an AlN ceramic substrate, b is a mixing diagram of AlN and Cu, c is a Cu deposited layer, e is Ce evaporated, and d is Ar ions. In the figure, b + c is a metallized layer.

[Test Example] substrate: AlN, acceleration energy: 25 keV, chamber vacuum: 10 ^-6 torr, ion species: Ar, coating species: Samples prepared with Cu ⁺ Ar + + Cu, the metal deposition layer surface, an epoxy-based adhesive And a tensile test was performed by bonding an aluminum pull rod.

Actually, ion irradiation is stopped when the peak of the implantation depth reaches the substrate interface in consideration of the sputtering rate. The number of ions irradiated up to that time is defined as a dose.

FIG. 2 shows the test results showing the adhesion strength (kg / mm ² ) with respect to the ion implantation amount (pieces / cm ² ).

From this test result, when mixing with Ar ions, 1 × 10 ¹⁶
Irradiation of 1 × 10 ¹⁷ / cm ² Ar ions from 1 / cm ² unit gives a stable adhesion strength of 4 to 7 kg / mm ² , and 1 × 10 ¹⁵
Ar / irradiation dose of ² units / cm ² is not stable, but 2-3k
It was found that a strength of around g / mm ² was obtained. As a result, an ion irradiation dose of 1 × 10 ¹⁵ to 1 × 10 ¹⁶ / cm ² can be obtained for practical use.

 In the drawing, black indicates adhesive breakage and white indicates coating peeling.

[Effects of the Invention] AlN was hardly wet with Cu and was difficult to join. However, according to the method of the present invention, the ion irradiation dose was 1 × 10 ¹⁵ to 1 × 10 ¹⁸
By setting the pressure to / cm ² , a material having an adhesion strength that can withstand practical use of Cu and AlN can be obtained.

BeO and Al ₂ O ₃
It can be used for IC packages that require heat dissipation instead of ceramics.

Further, unlike the conventional method, high temperature heat treatment is not required, and the AlN ceramic surface can be metallized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a surface layer cross section of an AlN ceramic material obtained by the present invention. FIG. 2 shows an example of test results according to the present invention. FIG. 3 is a schematic diagram of an apparatus for practicing the present invention. 1 ... Vacuum chamber, 2 ... Rotary sample holder, 3
... Electron beam heating evaporation source, 4 ... Bucket type ion source.

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein C is deposited on the surface of the AlN ceramic material by vapor deposition of Cu.
While forming the u layer, the Cu layer surface is converted to AlN ceramic material.
A method for producing a substrate for a highly thermally conductive IC, comprising irradiating 1 × 10 ¹⁵ to 1 × 10 ¹⁸ ions / cm ² with Ar ions.