JPH01216560A - Board for die bonding semiconductor device - Google Patents

Abstract

PURPOSE:To improve heat sink and electric insulation by laminating a diamond layer of specific thickness through a high melting point metal layer made of W, Mo, Ta, Nb or Hf with specific thickness on the semiconductor chip brazing face and circuit forming of an Fe series alloy body containing high Ni content. CONSTITUTION:A diamond layer having 0.1-20mum of mean thickness is laminated through a high melting point metal layer made of W, Mo, Ta, Nb or Hf with 0.01-1mum of mean thickness on the semiconductor chip brazing face and circuit forming face of an Fe series alloy body containing high Ni content. Thus, a board for die bonding a semiconductor device with excellent electric insulation and heat sink is formed. A substrate B is charged with the metal layer disposed upside in a quartz reaction tube A of a chemical vapor deposition unit, the unit is evacuated in vacuum and degassed, and a metal tungusten filament C placed 3cm separately from the surface of the substrate B is heated to 2000 deg.C. Mixture reaction gas D of CH4 and H2 is introduced from the top of the tube A, vapor precipitation reaction is executed, thereby forming a diamond layer of mean thickness.

Description

[Detailed description of the invention] [Industrial application field] This invention has excellent electrical insulation and heat dissipation properties,
The present invention also relates to a substrate for die bonding of semiconductor devices which has excellent brazing properties with semiconductor chips and excellent adhesion with formed circuits.

[Conventional technology]

Generally, as a substrate for die bonding of a semiconductor device, as described in Japanese Patent Application Laid-Open No. 81-30042,
4270I with a composition of Fe-42%Ni, Fe-
The semiconductor chip brazing surface and circuit forming surface of the main body made of a high Ni-containing Fe-based alloy such as Kovar having a composition of 29% Ni-17% Co are coated with AfI203. BeO.

Those coated with a ceramic layer made of SiC, A#N, 5t3N4, etc. and having an average layer thickness of 3 to 15 μm are widely used.

[Problem to be solved by the invention]

On the other hand, in recent years, as electronic devices have become more sophisticated, lighter, thinner, and smaller, the integrated circuits of semiconductor devices are also becoming more dense.
As a result, problems arise, for example, in electrical insulation and thermal conductivity between the substrate and the semiconductor chip. In other words, as the density of integrated circuits increases, the ceramic layer of the substrate becomes a capacitor between the semiconductor chip and the circuits formed on it, which has a negative electrical effect on the integrated circuit. This is because the ceramic layer has a high dielectric constant, and in order to solve this problem,
It is necessary to thicken the ceramic layer to a thickness of 20 μs or more.

However, if the ceramic layer in the substrate is made thicker, the heat dissipation performance will be significantly reduced, causing the problem that the semiconductor device will no longer function adequately due to the high temperature.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a substrate for die bonding of semiconductor devices with excellent heat dissipation and electrical insulation properties, and as a result, they found that layer,
In place of the diamond layer, which also has excellent brazing properties with the semiconductor chip and adhesion with the formed circuit, as well as excellent heat dissipation and electrical insulation properties, in this case, the above-mentioned high Ni-containing Fe, which constitutes the diamond layer and the substrate body, is used. The adhesion with the alloy is extremely poor, and the rate of vapor phase precipitation of diamond is also extremely slow. , Mo, TB, Nb
When diamond is deposited in a vapor phase by, for example, chemical vapor deposition through a high melting point metal layer made of Hr or Hr, a diamond layer is formed at a high deposition rate,
Moreover, this diamond layer is extremely strongly bonded to the high Nl-containing Fe-based alloy main body through the high melting point metal layer. They found that there is no peeling, and the diamond layer ensures excellent heat dissipation and electrical insulation, resulting in extremely high reliability.

This invention was made based on the above knowledge, and the average layer thickness: Q, Ql~1
W, Mo, Ta with μm.

Features of a substrate for die bonding of semiconductor devices with excellent electrical insulation and heat dissipation properties, which is formed by laminating diamond layers with an average layer thickness of 0.1 to 204 through a high melting point metal layer made of Nb or Hr. It has the following.

In addition, in the substrate of this invention, the average layer thickness of the high melting point metal layer is limited to 0.01 to 1-1.
．． If it is less than 1 μm, it will not be possible to form a diamond layer with a uniform thickness and good adhesion, while even if the average layer thickness exceeds 1 μm, the effect will only be saturated and the productivity and heat dissipation will be reduced. This is because it is disadvantageous from the point of view of It is small and therefore has excellent heat dissipation and compatibility with semiconductor chips.
Furthermore, since the dielectric constant is as small as 5.88 (500-3000Hz), it exhibits sufficient electrical insulation, but if the average layer thickness is less than O.la, it is difficult to ensure the desired heat dissipation, consistency, and electrical insulation. On the other hand, the average layer thickness is 20
Even if the thickness exceeds .mu.m, the above-mentioned effects are saturated and no further improvement is observed, so the average layer thickness was set at 0.1 to 20 u.

Further, the above-mentioned high melting point metal layer is formed by a normal sputtering method or a chemical vapor deposition method, and the above-mentioned diamond layer is formed by a normal chemical vapor deposition method or a plasma chemical vapor deposition method.
, and may be further formed by a photochemical vapor deposition method or the like.

Furthermore, in the substrate of the present invention, in addition to the above-mentioned 4270I and Kovar, the high Ni-containing Fe-based alloy constituting the substrate body may be one having a coefficient of thermal expansion close to that of a semiconductor chip or a ceramic case. Any material is acceptable, and high Ni cast iron can also be used.

〔Example〕

Next, the substrate of the present invention will be specifically explained using examples.

As the substrate body, rolled plate materials made of 4270 and Kovar with planar dimensions: umm x 25 mm, thickness 20 mm, and I1 m were prepared. Next, one side of each of these rolled plate materials was coated with a sputtering method using a normal sputtering method. A high melting point metal layer having an average layer thickness shown in Table 1 is formed, and then a first
Into a quartz reaction tube A of a chemical vapor deposition apparatus using the thermionic radiation material method shown in the schematic explanatory diagram in FIG. After evacuating the inside of the reaction tube A, a metal tungsten filament C placed 30I11 away from the surface of the substrate main body B is heated to 2000°C, and C10 is heated from the top of the reaction tube A.
and H mixed reaction gas D <0M4/H2-volume ratio 1/
99) at 300 Torr while maintaining the furnace pressure at 20 Torr.
ml/mln, and conduct a vapor phase precipitation reaction for a predetermined time to form a diamond layer having an average layer thickness shown in Table 1.
4 were produced respectively.

For comparison purposes, we used the same <4270 I and Kovar plate material as the main body of the substrate, and formed a ceramic layer on one side of this using the usual chemical vapor deposition method, with the average layer thickness shown in Table 1. Conventional substrates 1 to 1O were each manufactured.

Next, with respect to the various substrates obtained as a result, a dielectric strength test was conducted for the purpose of evaluating electrical insulation properties, and a scratch test was conducted for the purpose of evaluating the adhesion between the diamond layer and the ceramic layer.

In addition, the dielectric strength test was conducted based on JIS-C2110 by sandwiching the board between upper and lower electrodes with a diameter of 61 μm, applying a voltage of 500 V to this, and holding it for 1 hour, observing whether or not electricity was applied during this time. and shown in Table 1.

The scratch test was carried out using a normal scratch tester at a loading speed of ION/s1n to measure the critical load, which is shown in Table 1 as the average value of 10 tests.

〔Effect of the invention〕

From the results shown in Table 1, it can be seen that the diamond layer of substrates 1 to 24 of the present invention has excellent adhesion comparable to that of the ceramic layer in conventional substrates 1 to 1O, while the electrical insulation properties are superior to those of the conventional substrates. It is clear that it is far superior.

In addition, we attempted to form a diamond layer on 4270I and Kovar plates, which do not have a high-melting point metal layer, but in this case, diamond precipitation was extremely slow and it was impossible to form a diamond layer on a practical scale. Ta.

As described above, the substrate of the present invention has excellent electrical properties due to the diamond layer firmly bonded to the semiconductor chip brazing surface and circuit forming surface of the main body made of a high Ni-containing Fe-based alloy via a high melting point metal layer. Insulation and heat dissipation properties are ensured, and this diamond layer also has excellent brazing properties with semiconductor chips and adhesion with formed circuits.
It has industrially useful properties such that it can be put to practical use as a die bonding substrate for highly integrated semiconductor devices that generate a high amount of heat.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an apparatus for forming a diamond layer using the thermionic emitter method. A...Quartz reaction tube, B...Substrate body, C...
...Metal tungsten filament, D...Reactive gas. “

Claims (1)

[Claims] (1) Average layer thickness: 0.01~
Through a high melting point metal layer made of W, Mo, Ta, Nb, or Hf having a thickness of 1 μm, the average layer thickness is 0.1 to 20 μm.
A substrate for die bonding of a semiconductor device, which is formed by stacking m diamond layers.