JPS61288447A - Semiconductor element mounting substrate - Google Patents

Abstract

PURPOSE:To make it possible to apply thick film pastes and a glass film on the surface of an AlN substrate by a method wherein a coating layer consisting of a substance to be chosen from among an SiO2, an Al2O3, an MgO and a diamond is provided on the surface of the substrate. CONSTITUTION:A coating layer 2 consisting of some of an SiO2, an Al2O3, an MgO and a diamond or the mixture of these substances is formed on the surface of an AlN substrate 1. There is no limitation specially to the forming method for the coating layer 2, but such a method as a vapor-phase reaction method, a plasma CVD method and a PVD method is desirable in point of being able to form the coating layer with a favorable adhesion with the AlN substrate with good productivity efficiency. The circuits are formed on the substrate, whereon the coating layer is obtained in such a way, using thick film pastes 3 and a sealing glass film 6 is adhered on the sealing part. Lastly semiconductor elements 4 are connected to the prescribed positions on the circuits using element bonding materials 5. The covering layer 2 can be formed on the whole or part only of the surface of the substrate 1 according to need. The coating layer 2 has an electrical resistance, and moreover, has a good leakage property into the thick film pastes and the glass film. Accordingly the thick film pastes for circuit formation and the glass film for sealing can be applied on the coating layer 2 of the substrate by a screen printing and so forth.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a substrate 1 for mounting semiconductor elements, particularly a substrate 1 having good heat dissipation properties, coatability of thick film paste, and glass sealability with low melting point glass or the like. This invention relates to a board with improved characteristics.

[Conventional technology]

Generally, a circuit board for mounting a semiconductor element is prepared by drawing a circuit on its surface with conductive paste as necessary, brazing the semiconductor element in a predetermined position or adhering it with an adhesive paste, and finally using resin, glass, or brazing material. Hermetically sealed. Therefore, the characteristics required for the substrate are as follows:
It was important that the coefficients of thermal expansion and the thermal expansion coefficients matched, but in recent years, as single-piece semiconductor devices have become denser and have higher power, the heat dissipation characteristics to effectively remove the Joule heat generated in the devices have also become important. It has become important again.

Conventionally, AlO was often used as a substrate material, and there was no problem when the semiconductor element was small and the stress caused by the difference in thermal expansion coefficient with A40 was small. However, as semiconductor devices become larger, the thermal expansion coefficients of A10 and A81 differ by 2.7X10/l, as shown in Table 1 below, so the stress caused by this difference increases, causing the devices to peel off. or destruction will occur.

Also, from the point of view of heat dissipation characteristics, Aj0 has extremely low thermal conductivity as shown in Table 1, so it cannot be said to be effective as a substrate material, and if the Joule heat generated in the device is large, Cu
Efforts have been made, such as installing heat sinks such as and Aj.

Table 1 Therefore, AIN shown in Table 1 has been proposed as a substrate material with a thermal expansion coefficient close to 81 and good thermal conductivity, and has been used in some cases. However, AIN has poor wettability with thick film pastes and glass, and its practical range has been limited.

[Problem that the invention seeks to solve]

The present invention uses klN, which has a coefficient of thermal expansion similar to that of Sl and has good heat dissipation properties, to provide a substrate for mounting a semiconductor element on the surface of which a thick film paste and glass can be applied.

Means for Solving Problem C] The substrate for mounting a semiconductor element of the present invention has a coating layer made of at least one substance selected from the group consisting of S10, AlO1Mgo, and diamond on at least a part of the surface of the A4N base. It is characterized by having the following.
``The thickness of the coating layer is preferably 0.1 to 20 μm. If this thickness is less than 0.1 μm, the coating and adhesion of the thick film paste or glass will be insufficient, and if it exceeds 20 μm, the coating layer itself will act as a barrier to heat dissipation, making it impossible for AIN to exhibit its excellent heat dissipation properties. First, the coating layer is likely to peel or break due to the difference in thermal expansion coefficient between the coating layer and A4N.

Next, the semiconductor element mounting substrate of the present invention will be explained based on the drawings. AlN formed into a predetermined shape by a normal method
A coating layer 2 made of any one of S10, Al01Mg0, and diamond or a mixture thereof is formed on the surface of the substrate 1. There are no particular restrictions on the method of forming the coating layer 2, but for example, a vapor phase reaction method (avD method: OhmicaJ
Vapor Deposition), plasma OVD method, PVD (Phya soil cal V'apo
The Deposit-1on) method is preferred in that it can form a coating layer with good adhesion to the AlN substrate with high productivity. On the substrate of the present invention obtained in this way,
A circuit is formed using the thick film paste 3, and a sealing glass 6 is attached to the sealing portion. Finally, the semiconductor element 4 is connected to a predetermined position on the circuit using the element bonding material 5. Note that the coating layer 2 may be formed on the entire surface of the substrate 1 or only on a part of the surface, if necessary.

[Effect]

In the present invention, Sio and Ato constituting the coating layer
, Mg0 or diamond have electrical insulation properties and also have good wettability with thick film pastes and glass.

Therefore, it is possible to apply a thick film paste for circuit formation or glass for sealing onto the coating layer of the substrate by screen printing or the like. Moreover, this coating layer has a thickness of 20 μm.
If it is below, the Joule heat generated in the semiconductor element is
Does not interfere with dissipation from the N substrate.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example I AIO was deposited on an AlN substrate by ion blating method.
A covering layer was formed to produce a Hybrid E-C substrate.

First, prepare an AlN substrate with a diameter of 40 mm, a thickness of Q, and 5 mm.
This was preheated to 2001:' and set in a vacuum container. Using an Alo sintered body as the raw material for the coating layer, AAO was evaporated by electron beam heating under 1 oxygen pressure and a force of 5 x 10-'torr, and a high-frequency coil was heated at 13.56 mm.
Evaporate klO by applying MHz high frequency at 100W.
2.0 μm thick on the surface of the A4N substrate.
A N-coated layer with good adhesion was formed.

On the obtained hybrid TC substrate, Ag paste was applied to a thickness of 12 μm by screen printing method and baked at 560C for 10 minutes in the air.
A substrate for hybrid E-C with good adhesion to the O coating layer was obtained.

Example 2 A glass-sealed package substrate was manufactured by forming an Al 2 O coating layer on an AlN substrate by plasma OVD.

20 angles, thickness Q, Qmm, 6 angles in the center, depth 0.3
Set the AIN substrate with four parts in the reaction chamber, A, /
A40 was vapor-phase grown on the substrate using a mixed gas of C+7, co and H at a total gas pressure of 1.5 torr. At this time, the reaction chamber was heated to 13.5
A high frequency of 6 MHz was applied at 300W. The resulting Al2O3 coating layer had a thickness of 3.0 μm and had good adhesion to the A/N substrate.

Au paste was dropped into the concave portions of the obtained glass-sealed package substrate by a dotting method, and fired at 850C for 10 minutes in the air. Next, apply low melting point glass to the outer periphery of the four parts by screen printing method, and heat at 450C for 1 hour.
It was baked in the air for 0 minutes. After that, Al was applied to the lead tip.
A 42% Ni-Fe lead frame on which was vapor-deposited was bonded to the glass part with 4800.

A semiconductor element was bonded to the Au portion of the glass-sealed package obtained in this manner by the Au-3i eutectic method, and the leads and electrodes of the semiconductor element were bonded with At wire. Finally, the A40 plate coated with glass and this package were hermetically sealed with 5000mm. After hermetically sealing, a predetermined heat cycle pressure test is carried out.
As a result of measuring the amount of adhesion between the glass, the Al2O3 coating layer 1AIO coating layer, and the A4N substrate, it was found that there was no leakage at all and a sufficient hermetic seal was obtained.

Example 3 Aj
! A substrate for mounting a semiconductor element was manufactured by coating with a mixture of O, MgO and SiO.

First, an AIN substrate of 2 inches square and 1 am thick was fixed to a sample holder in a sputtering container in which an At 2 O target embedded with MgO and SiO□ was set as a target in advance. Next, the inside of the sputtering container was
At the same time as pulling the
000, introduce Ar gas to a gas pressure of 5 x 10 torr, and apply a high frequency of 13.56 MHz to the target.
Apply xw to sputter the target at 1A
/N Al01 with a thickness of 3.0 μm and good adhesion to the substrate surface
A mixed coating layer of Mg0 and SiO was formed.

Au paste was applied to a thickness of 15 μm by screen printing on the obtained substrate for mounting a semiconductor device, baked at 900 C for 10 minutes in the air, external leads were soldered onto the Au, and a tensile test was conducted. As a result, a tensile strength as high as 4.5 was obtained, and a semiconductor element mounting substrate with good adhesion was obtained.

〔Effect of the invention〕

The substrate for mounting a semiconductor element of the present invention has the following features: (a) Since A4N, which has a thermal expansion coefficient similar to that of Si, which is the semiconductor element material, is used as the base, stress due to the difference in thermal expansion coefficient between the substrate and the element is small, and the element No peeling or destruction occurs. Furthermore, since A4N has high thermal conductivity, the heat dissipation characteristics of the entire board are also good.

(b) At least a part of the surface of the iN substrate has Si0
.

having a coating layer made of at least one substance selected from the group consisting of AIO, MgO and diamond,
These coating layer materials are electrically insulating and have good wettability with the thick film paste and glass, so it is possible to apply the thick film paste to the substrate and seal it with glass while maintaining the electrical insulation of the AIN substrate. is possible.

Therefore, the present invention provides a substrate for mounting a semiconductor element that can fully cope with the increase in size, density, and power consumption of semiconductor elements, and has great technical and economical effects.

[Brief explanation of drawings]

The drawing is a sectional view showing a specific example of the substrate of the present invention on which a semiconductor element is mounted. 1. AjN substrate, 2. Covering layer, 3. Thick film paste, 4. Semiconductor element, 5. Semiconductor element bonding material, 6.
- Sealing layer glass.

Claims (2)

[Claims] (1) SiO_
2. A substrate for mounting a semiconductor device, characterized by having a coating layer made of at least one substance selected from the group consisting of Al_2O_3, MgO, and diamond. (2) The substrate for mounting a semiconductor element according to claim (1), wherein the thickness of the coating layer is 0.1 to 20 μm.