JPS61121489A - Cu wiring sheet for manufacture of substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a Cu wiring sheet for producing nine substrates by improving the bondability with a ceramic substrate.

[Technical background of the invention and its problems]

Generally, ceramic substrates are often used as insulating materials for semiconductor substrates, such as semiconductor modules. When applied to these ceramic substrates, especially high-power semiconductor substrates, Cu members (
A bonding technology between the Cu wiring sheet) and the ceramic substrate is essential.

Conventionally, most of the ceramics used for such substrates were At203, but in recent years At203 has been used to radiate heat generated from semiconductor elements from the substrate as well.
Highly thermally conductive ceramics such as AtN, which have excellent not only electrical insulation properties but also heat dissipation properties, have been developed, and their wide range of applications are expected.

However, since ceramics and metals have different atomic bonding states, when they are joined together, their chemical properties such as reactivity and physical properties such as thermal expansion coefficients are also significantly different. In particular, nitride ceramics such as AtN ceramics have poor wettability with metals compared to oxide ceramics such as At203, and the commonly used bonding methods such as high-melting point metal metallization bond Cu wiring sheets. Unable to do so, A
It has been difficult to manufacture semiconductor module substrates using tN ceramic as substrates.

[Purpose of the invention]

The present invention solves the above-mentioned problems and provides a Cu wiring sheet for manufacturing substrates that can be easily and firmly bonded to a ceramic substrate and has excellent workability.

[Summary of the invention]

The present invention provides an active layer made of an active metal or an active metal and a soft metal on the surface of a thin Cu plate serving as a wiring layer, and the active layer is placed on the ceramic substrate side and heated to alloy the active layer. It is characterized in that it can be firmly bonded to a ceramic substrate.

The present invention will be explained in detail below.

In the present invention, the active metal to be used as the active layer is at least one selected from group F/A elements of the periodic table, such as Tj, Zr, and Hf, or an alloy containing these as main components. used. Further, examples of the soft metal include Ag or Cu.

In addition, the ceramic substrate to which the Cu wiring sheet of the present invention is bonded is At203, which is commonly used in the past.
In addition, aluminum nitride (A/, N) and silicon carbide (St
It can be widely applied to high thermal conductivity ceramics such as C).

In the present invention, the thickness of the active layer formed on the surface of the Cu thin plate is preferably about 0.5 to 10 μm, and when the active layer is a composite layer of an active metal and a soft metal such as Ag or Cu, The thickness of the metal layer is 0.1 to 5 μm.

By setting the Ag layer to 9 μm or less and the Cu layer to 9 μm or less, excessive bonding material (active layer) does not protrude from the bonding interface between the Cu thin plate and the ceramic substrate, allowing easy and reliable bonding. can do.

For example, if the T1 layer is a single layer, its thickness is 0.5 to 1
0 μm is preferable, and when providing an active layer with a thickness of 0.5 to 10 μm consisting of a composite layer of Ag layer + Ti layer, A
The g layer is 0.2-9 μm, and the active metal layer such as Ti is 0.1-9 μm.
The thickness is preferably 5 μm. Also, Ag layer + Ti layer -)
- When providing a composite layer with a thickness of 0.5 to 10 μm consisting of three Cu layers, the active metal Kj such as AgJ@0.2 to 9 μm and T1 layer should be 0.1 to 5 μm x Cu layer 9 μm or less. preferable.

The reason why the thickness of the active layer is limited to the above range in the present invention is that if the thickness is less than 0.5 μm, high bonding strength between the Cu wiring sheet and the ceramic substrate cannot be obtained;
This is because if μm is lowered, the molten material will protrude and spread to the outside of the bonded portion during heating and melting, and the function as an insulating substrate will be impaired, such as short-circuiting with adjacent wiring layers.

In the present invention, examples of methods for providing an active layer on the surface of a Cu thin plate include the following method.

■ Method of directly depositing active metal layer or soft metal layer by methods such as vapor deposition, sputtering, plating, etc. ■ Method of bonding active metal or soft metal foil onto Cu thin plate with adhesive, ■ Method of bonding active metal or soft metal layer onto Cu thin plate A method may be used in which metal powder is made into a paste form using an organic solvent or the like and applied onto the Cu thin plate, or a method in which the above methods 1 to 2 are combined.

In the present invention, the ceramic substrate of the active layer and the Cu thin plate may be interposed in any order, but from the surface side of the ceramic substrate, first the active metal layer, then the soft metal layer, especially the Ag layer and the Cu layer. The most stable joint can be obtained by intervening in sequence. Further, in the case of a composite layer of an active metal layer and a soft metal layer, each metal layer is not limited to one layer at a time, and a plurality of layers may be interposed.

Further, the Cu wiring sheet of the present invention may be processed into the desired shape by any method such as press processing or photo-etching, but the sheet of the present invention has four Cu layers that are highly ductile and easily etched. Since it has a structure that is used as a base and only an active layer of 10 μm or less is provided on it, it has excellent processability.

Next, a method for bonding the Cu wiring sheet of the present invention to a ceramic substrate will be explained.

The Cu wiring sheet of the present invention is stacked with its active layer side on a ceramic substrate, and the bonded portion between the two is heated by high frequency induction or the like in a vacuum atmosphere or an inert gas atmosphere. In this case, pressure is basically not required during heating, but the load is low enough to bring the bonding interface into close contact (0 to lK4/l
t') may be added.

Also, the heating temperature needs to be lower than the melting point of the Cu thin plate.
Preferably, heating may be performed within a range of 780 to 1082°C. Through such heat treatment, for example, Cu--Tl is formed between the ceramic substrate and the Cu thin plate.

Alternatively, a composite liquid such as Ag-Cu-Ti is produced,
This joint liquid will not spill out to the outside of the joint.
The subsequent cooling solidifies the ceramic substrate and Cu.
The thin plate is firmly bonded to produce a ceramic substrate suitable for high-power semiconductor substrates and the like.

[Embodiments of the invention]

(Example 1) C with T1 deposited to a thickness of 5 μm by vapor deposition as an active layer
The u wiring sheet 1 is processed into a predetermined shape by photoetching. Next, as shown in FIG. 1, after cleaning and degreasing the multiple Cu wiring sheets 1 and the AtN substrate 2, which also serves as an insulating plate, a heat sink, and a heat sink, with trichlene and acetone, the active layer is used as a bonding surface. , and placed on an AtN substrate 2, and set in a hot breath maintained at a vacuum level of 2×10 Torr.

Next, between the AtN substrate 2 and the Cu wiring sheet 1, there is a 0.00 mm vertical diagonal. The joint was held at 930°C for 10 minutes by high-frequency induction heating while applying a pressure of IK9/-, and the Cu
-Ti alloy liquid was produced. After heating, the substrate is cooled in an Ar gas atmosphere, and as shown in FIG. 1, a T4 semiconductor module substrate is obtained by bonding the Cu wiring sheet 1 on the AtN substrate 2 to the alloy layer 3 in which the T1 active layer is melted and solidified. 4 was manufactured.

Power semiconductor monoale substrate 4 obtained in this way
A good bonding state was obtained in which the AtN substrate 2 and the Cu wiring sheet 1 were firmly bonded by the alloy layer 3, and the alloy layer 3 did not protrude from the bonded portion.

Further, as shown in FIG. 2, a semiconductor element 5 was mounted on the module substrate 4 via a Pb-8n solder 6.

Regarding this power semiconductor module, when the thermal conductivity from the semiconductor element 5 to the AtN substrate 2 direction (thickness direction) was measured, it was 88 W/-1. Pass through sheet 1 and alloy layer 3.
It releases well to the tN substrate 2, and connects the Cu wiring sheet 1 and AtN.
It was confirmed that the bonding with the base body 2 was good.

(Example 2) A Cu wiring sheet 1 on which 2 μm of T1 was deposited as an active layer by vapor deposition and a 5 μm thick Ag foil was adhered thereon using an organic solvent was punched into a predetermined shape. Next, after cleaning and degreasing this Cu wiring sheet 1 and the AtN substrate 2 with trichlene and acetone, A
It was placed on a tN substrate 2 and set in a hot breath maintained at a vacuum level of 2×10 Torr.

Next, a pressure of 0.05K97M12 was applied from above and below between the AtN substrate 2 and the Cu wiring sheet 1, and the joint was heated to 830°C for 10 minutes by high-frequency induction heating to form a Tl
-Ag-Cu alloy liquid was produced. After heating, the power semiconductor module substrate is cooled in an Ar gas atmosphere, and the Cu wiring sheet 1 is bonded to the AtN substrate 2 using an alloy layer in which the Ti-Ag active layer is melted and solidified as shown in FIG. 4 was manufactured.

Power semiconductor monoyl substrate 4 obtained in this way
A good bonding state was obtained in which the AtN substrate 2 and the Cu wiring sheet 1 were firmly bonded by the alloy layer 3, and the alloy layer 3 did not protrude from the bonded portion.

〔Effect of the invention〕

As explained above, the Cu wiring sheet for manufacturing substrates according to the present invention can be easily and firmly bonded to ceramic substrates, has excellent workability, and is particularly suitable for use with AtN substrates that have poor wettability with metals. It has excellent bonding properties and is suitable for manufacturing power semiconductor mosoule substrates that have both insulation and heat dissipation properties.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a power semiconductor monolithic board according to an embodiment of the present invention, and FIG. 2 is a sectional view of a power semiconductor module in which semiconductor elements are mounted on the module board of FIG. 1. 1...Cu wiring sheet, 2...AtN base, 3...
・Alloy layer, 4...! semiconductor monoyl substrate, 5
... Semiconductor element, 6... Solder. Applicant's agent Patent attorney Takeshi Suzue Industry 1 Figure 2

Claims (3)

[Claims] (1) A Cu wiring sheet for substrate production, characterized in that an active layer consisting of an active metal or an active metal and a soft metal is provided on the surface of a Cu thin plate. (2) Active metal layer with active layer of 0.1-10 μm, 9 μm
2. The Cu wiring sheet for manufacturing a substrate according to claim 1, comprising the following Ag layer and a Cu layer of 9 μm or less, and the total thickness of the active layer is 0.5 to 10 μm. (3) Claim 1, characterized in that the active metal is at least one selected from Group IVA elements of the periodic table, or an alloy containing the same as a main component.
Cu wiring sheet for manufacturing a board as described in .