DE2352329B2 - SEMICONDUCTOR COMPONENT AND METHOD FOR ITS PRODUCTION - Google Patents

Description

( / CO _x / CO _x

—4-R'-N R N-

in which the radicals R 'and R are aromatic radicals and with through the SiO2 layer (23) and through the Polyimide resin layer (24) on the surface of the semiconductor body (20) extending through connection electrodes (25, 28; 39, 40), characterized in that the assemblies have the special structure

CO _x / CO _x / CO _x / CO _x

/ Ar, N-Ar ₁ -N Ar ₄ N-

/ / ^ CO ^{7 ν} το ^χ Vo ^x

N-C

-At

C-N

Il ο

and the radicals Ar ₁ and Ar3 are groups derived from benzene, diphenyl ether, naphthalene, diphenyl sulfone and di- (phenoxyphenyl) sulfone and the radicals Ar2 and Ar ₄ are radicals derived from benzene, diphenyl ether and benzophenone.

2. Semiconductor component according to claim 1, characterized in that the radicals An and An are derived from diphenyl ether groups, the radical Ar _{2 is} a group derived from benzene and the radical Ar4 is a group derived from benzophenone.

3. Semiconductor component according to claim!, Characterized by a polyimide resin layer (24), obtained by polycondensation of 5 mol% 4,4'-diaminodiphenyl ether-3-carboxamide ₎ 45 mol% 4,4'-diaminodiphenyl ether, 25 mol % Pyromellitic dianhydride and 25 mole% 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride.

4. Semiconductor component according to one of claims 1 to 3, characterized by a primer (36) made of an organic material, such as an aminosilane compound or an epoxysilane compound, inserted _{between the SiO 2 layer (23) and the polyimide resin layer (24).}

5. Semiconductor component according to claim 4, characterized in that the primer (36) also is applied between the connection electrodes (25, 28; 39, 40) and the polyimide resin layer (24).

6. Semiconductor component according to one of claims 1 to 5, characterized by a thickness of the Polyimide resin layer (24) from 2 to 15 μίτι.

7. Method of manufacturing a semiconductor component according to one of claims 1 to 6, in which a polyimide resin solution is applied to the SiO2 layer is applied, wherein the device for applying the solution and the semiconductor body rotate relative to each other, in which the solution is hardened by heating in which the polyimide resin layer and the SiO2 layer is etched so that openings for the connection electrodes are formed and in the case of the electrode metal within the

35

40

45

55

6o openings is deposited, characterized in that the semiconductor body (20) is rotated when the solution is applied, that the polyimide resin layer (24) is etched with an oxygen plasma and that the electrode metal is evaporated or sputtered while rotating the semiconductor body (20).

8. A method for producing a semiconductor component according to claim 5, in which a polyimide _{resin solution is applied to the SiO 2} layer and cured by heating, in which the polyimide resin layer formed is etched, in which openings for the connection electrodes are formed in the SiO2 layer and is deposited in the electrode metal within the openings, characterized in that _{openings for the connection electrodes (39, 40) are first formed in the SiO 2} layer (23), and then the electrode metal is applied to the SiO ₂ layer (23) is applied and etched in such a way that _{electrodes (39, 40) protruding over the surface of the SiO 2} layer (23) with a trapezoidal cross-section are formed so that the surface of the SiO ₂ layer (23) and the electrodes (39, 40) primed and the polyimide resin layer (24) is applied to the primer (36) and that then the polyimide resin layer (24) is evenly removed so far with an oxygen plasma d until the upper horizontal surface of the electrodes (39, 40) is exposed in the plane of the surface of the polyimide resin layer (24).

The invention relates to a semiconductor device with a lying on the surface of the semiconductor body and a SiO ₂ layer overlying the SiO ₂ layer protective layer of a polyimide resin having

General structure assemblies

/ CO _n / CO _n \
'-N ^ R n4-

ir. which the radicals R 'and R are aromatic radicals, and through the SiOr layer and through the polyimide resin layer connecting electrodes extending through the surface of the semiconductor body.

The Polyirüdharz layer serves to protect the semiconductor component as well as the fully automatic one Soldering of the connecting wires. During this process, the coated component is initially immersed in a bath with the molten solder to make the solder beads. The polyimide resin layer must not change either with this dipping or with the later melting of the solder balls, neither with regard to their chemical nor in terms of their mechanical, nor change with regard to their electrical characteristics.

A semiconductor device of the kind mentioned is known, the polyimide resin layer is even with very thin training in a bath of molten lead-tin solder, that is at a soldering temperature of about 180 to 200 ⁰ C, not attacked from the DT-AS 17 64 977 and adheres well to the SiOj layer. When using solders with a higher melting temperature, in particular with solders with a melting temperature of more than approximately 350 ° C., however, the electrical characteristics of the polyimide resin layer of the known semiconductor component are deteriorated by orders of magnitude. In the case of the component, this leads to a noticeable increase in the leakage current and, in the case of transistors, for example, to a noticeable reduction in the gain factor. In addition, the dielectric breakdown strength of the polyimide resin layer used in the known semiconductor component is not too great, even at room temperature, with values between about 250 to 300 V / μΐη.
The miniaturization efforts in the field of semiconductor components also stand in the way of automating the production of the wire connections. Available in common semiconductor components for making the wire connections

ίο standing electrode surfaces have a diameter in the range of about 60 to ΙΟΟμπι, in view of the reduction in surface dimensions of semiconductor components sought for technical and economic reasons, an enlargement of the connection electrode surface could only be achieved if it extends beyond the connection window onto the outer insulator layer of the semiconductor component is extended beyond. The materials commonly used for these insulator layers, including the polyimide resins known from DT-AS 17 64 977 , have such unfavorable dielectric and / or thermal characteristics that such an enlargement of the connection electrode surface is forbidden for capacitive reasons.

In view of this prior art, the invention is based on the object of a semiconductor component of the type mentioned to create the wire connections even at high soldering or welding temperatures with relatively simple mass production equipment without affecting the electrical characteristics of the component can be produced.

To solve this problem, a semiconductor component of the type mentioned is proposed which according to the invention is characterized in that the Assemblies the special structure

CO _n / CO _n / CO _n / CO _n

/ Ar ₂ N-Ar ₁ -N Ar ₄ N

/ / Vo ⁷ ^ co '

N-C

-Ar

CN
O

and the radicals Ari and Ar _{3 are groups derived} from benzene, diphenyl ether, naphthalene, diphenyl sulfone and di- (phenoxyphenyl) sulfone and the radicals Ar2 and Ar ₄ are radicals derived from benzene, diphenyl ether and benzophenone.

This semiconductor component can also solder temperatures in the range from 300 to 450 ° C, sometimes also higher temperatures, without affecting its electrical or dielectric properties its polyimide resin layer.

The invention is described below using exemplary embodiments in conjunction with the drawings explained in more detail. It shows

F i g. 1 a common planar transistor,

Fig. 2 to 2b an embodiment of the invention and its production,

F i g. 3 a second embodiment of the invention,

4 to 4b a third embodiment of the invention and its production,

F i g. 5 to 5c a fourth embodiment of the invention and its production and

6 shows a graph of the production yield in connection manufacture as a function of dei Thickness of the polyimide resin layer.

For a better understanding of the invention is in dei Fi g. 1 initially shows a common planar transistor with a collector substrate 1, a base 2, an emitter 3 and an insulator layer 4. In connection windows star, which are opened in the insulator layer 4, a «base electrode 5 and an emitter electrode 6 are angeord net, to which the base connection wire 7 and the emitting connection wire 8 are attached. The diameter of the electrodes 5 and 6 is, as stated above, usually in the range from 60 to 100 μm. In the case of silicon semiconductor components, the insulator layer is usually an SiO ₂ layer which, for technical and economic reasons, is not significantly thicker than about 1 μm. An enlargement of the / 1 connection purposes available surface of the electrodes 5 and 6 over the diameter de; Window on the surface of the insulating layer <brings out interference capacitances to the base and to the emitter

The same effect already occurs with the one shown in FIG. 1 shown solder distribution during connection production on. The disadvantages resulting therefrom are eliminated by the invention, without a relatively large one Terminal electrode surface, which is the basis of mass production, needs to be dispensed with.

As a first exemplary embodiment of the invention, FIG. 2 shows a planar transistor. An n-Si substrate serves as a collector. A p-conducting base 21 and an η-conducting emitter 22 are formed in the substrate using planar technology. The surface of the substrate 20 is covered with an SiO2 layer 23 and this with a polyimide resin layer 24. The polyimide resin layer 24 is 5 μm thick. Through an opening in the polyimide resin layer 24 and the SiO ₂ layer 23, a base connection electrode 25 extends through both layers onto the base region of the transistor. The base electrode 25 consists of two metal layers. The first metal layer lies on the surface of the transistor base and establishes the connection between this and the: o second metal layer 27, which extends in part to the surface of the polyimide resin layer 24. In the same way, an emitter electrode 28 also consists of a first metal layer 29 and a second metal layer 30. A base connection wire 31 and an emitter connection wire 32 are attached to the surfaces of the electrodes.

The transistor shown in FIG. 2 is produced as follows: The base region 21 is formed by dit-fusing boron into the n-Si substrate 20. The emitter 22 is produced by diffusing phosphorus into the boron-doped area. Subsequently, the SiO2 layer 23 with the base connection window and the emitter connection window is applied. The aluminum layers 26 and 29 are introduced into the window as the first metal layer for the connection electrodes (FIG. 2a). The surfaces of the SiO ₂ layer 23 and the aluminum layers 26 and 29 are then coated with a 5 μm thick polyimide resin layer 24. A metal mask 33 is applied to the polyimide resin layer 24, in which windows 34 and 35 are opened at the points above the aluminum layers 26 and 29 (F 1 g. 2b). Then the polyimide resin layer 24 is removed through these windows 34 and 35 so that the surfaces of the aluminum layers 26 and 29 are exposed. After the mask 33 has been removed, the second electrode metal 27 or 28 is in the form shown in FIG. 2 applied with the production of an electrical contact to the aluminum layers. The connection electrodes 25 and 28 produced in this way also extend onto the surface of the polyimide resin layer 24 and thus provide a sufficiently large surface for the connection wires 31 and 32 to be welded or soldered on. Due to the excellent dielectric properties of the polyimide layer 2, which are not impaired even under the soldering temperature, the in FIG. The semiconductor component shown in FIG. 2 does not have any stray capacitances between the connection electrodes and the semiconductor.

The polyimide resin layer 24 is first applied in the form of a prepolymer solution The prepolymer solution is prepared, for example, by precondensing one composed as follows Get a mixture:

Non-volatile components:

4,4'-diaminodiphenyl

ether-3-carboxamide 5 mol%

4,4'-diaminodiphenyl ether 45 mol%

Pyromellitic acid dianhydride 25 mol% 3,3 ', 4,4'-Benzophenonetracarbon-

acid dianhydride 25 mol%

Solvent components:

N-methyl-2-pyrrolidone 50% by weight

N, N-dimethylacetoamide 50% by weight

concentration

of non-volatile substances 20% by weight

Solution viscosity about 300 cP

If this prepolymer solution is applied by the centrifugal method at a rotor speed of 5000 min- ¹ , a polyimide resin layer with a thickness of 1 μm is obtained. This thickness can be adjusted by changing the viscosity of the prepolymer solution, by changing the concentration of the non-volatile constituents, by changing the speed of the rotor or by a combination of these measures. Depending on the requirements of the individual case, polyimide resin layers in the order of magnitude from 1 to 10 μm can be produced. The thickness of the polyimide resin layer is preferably about 5 μm.

After the above-mentioned prepolymer solution has polymerized to completion, a polyimide resin is formed The SiOr layer is formed, which has assemblies of the following structure:

(ID

Windows in the polyimide resin layer are preferably opened using an oxygen plasma. When using a 0.7 kW plasma with an oxygen partial pressure of 0.8 mbar and a volume flow of 3 l / min is a 5 μm thick Polyimide resin layer is completely etched off after 10 minutes. This etching time can be changed by changing the oxygen volume flow, the oxygen partial pressure and / or the impressed high-frequency power is set

Since the plasma etching is carried out using a metal mask 33, it must be ensured that dl Mask either significantly thinner than the bottom one! Electrode metal layers 26 and 29 are formed or consists of a material that is characterized by eii Solvent can be peeled off that the electro

denmetallschichten 26 and 29 does not attack. In the embodiment described here, there are both Electrode layers 26 and 29 as well as the mask 33 made of aluminum. The mask is 0.4 μm thick, while the Electrode metal layers 26 and 29 are 1 μm thick. Under these conditions, the mask 33 are completely detached and at the same time the electrode metal layers 26 and 29 remain in sufficient Thick standing.

It is not necessary that the two metal layers ten one and the same electrode consist of different metals. In the embodiment described here the second electrode metal layers 27 and 30 also consist of aluminum. You will go through Vapor deposition of an aluminum layer on the surface of the polyimide resin layer 24 and in its opened Connection electrode window into it and subsequent selective etching of the vapor deposition layer. Around to ensure that the relatively deep window in the polyimide layer 24 during the vapor deposition of the aluminum are also evenly and completely filled, the semiconductor substrate 20 is during the vapor deposition preferably rotated

Another embodiment of the invention is shown in FIG. 3 shown. This transistor corresponds in essential ₂ .s chen the in F i g. 2 and differs therefrom in that an adhesion promoter layer 36 is inserted between the SiO2 layer 23 and the polyimide resin layer 24. The adhesion promoter contains alkoxysilane groups to mediate a chemical bond to inorganic materials as well as amino groups and / or epoxy groups to mediate chemical bonds to the polyimide resin layer.

Commercially available aminosilanes in the form of Solutions with concentrations of 0.05 to 20% by weight are used. A 1% strength by weight isopropanol solution is preferred of N-jS-iAminoäthyO-y-aminopropyl-methyldimethoxysilane used to produce the adhesion promoter layer 36. The applied solutions are usually about 30 minutes at 100 ° C dried.

The in the F i g. The embodiment of the invention shown in FIG. 4 differs from that in FIGS. 2 and 3 embodiments shown essentially in that the base electrode 25 and the emitter electrode 28 consist of only one metal layer each.

In the production of the in F i g. 4 is applied, the structure shown prepolymer of PoIyimidharzes previously described, after drying the adhesive layer 36, dried at 100 ⁰ C and then for 1 h cured at 300 ° C, the polyimide resin layer 8 μπι thick. An aluminum mask 33 with windows 34 and 35 is then formed on this polyimide resin layer 24 over the base region and the emitter region, respectively (FIG. 4a). By means of plasma etching, windows in the polyimide resin layer are then opened through the mask openings 34 and 35 down to the surface of the SiO2 layer. Using the window opened in this way in the polyimide resin layer, common etching agents are then also used in the exposed SiOj layer, for example a hydrofluoric acid ammonium fluoride solution. opened a window. In this way, terminal contact windows 37 for the base and 38 for the emitter that extend through the entire layer structure are created. After the aluminum mask 33 has been detached, an aluminum layer is applied by cathode sputtering, which also completely fills the windows while making electrical contact with the base and the emitter. The aluminum layer is then selectively etched to form the terminal electrode surfaces. The connecting wires 31 and 32 are then welded on by hot pressing or ultrasonic welding. Even the relatively thick polyimide resin layer withstands relatively high welding temperatures in the region of 450 ^° C. without any deterioration in its dielectric characteristics. Neither cracking nor a decrease in breakdown voltage occurs.

In FIG. Finally, FIG. 5 is a further exemplary embodiment of the invention, also using the example of one Planar transistor shown. The base electrode 25 and the emitter electrode 28 each consist of an im Cross-section of essentially trapezoidal metal web 39.40, the electrical contact to the Base or to the emitter produces and its upper end face in the surface of the polyimide resin layer 24 is exposed and there electrically conductive with connection plate 41, 42 is connected. The adhesive layer is not only between the SKV layer 23 and the polyimide resin layer 24 is inserted, but also encloses the one with the polyimide resin layer in Contacting side surfaces of the electrode webs 39,40.

In the manufacture of this component, the procedure is that the substrate surface is initially is covered with an S1O2 layer, in which then window to the base and to the emitter. A 5 μm thick aluminum layer is applied to this structure dejected. By selective etching ν the in F1 g. 5a shown Eiektrodenstege 3S and 40 on the Base and the E'.mitter formed. The structure obtained is on its entire surface with a Aminosilane adhesion promoter layer 36 coated. This layer is then applied in the manner described while rotating the semiconductor structure, a finally 6 μm thick polyimide resin layer is applied (FIG. 5b). By etching with an oxygen plasma, the structure obtained is removed evenly until the upper end faces of the electrode webs 39, 40 are exposed in the surface of the polyimide resin layer 24 The structure obtained is finally vapor-deposited with aluminum and the connection plates are formed 41, 42 selectively etched. After attaching the connecting wires 31 and 32 is the in F i g. 5 shown structure obtain.

In order to ensure the best possible surface formation zi, the polyimide resin layer 24 is in front preferably made so thick that they be well coated with the adhesion promoter electrode webs covers

The polyimide resin layer 24 preferably consists of a polymer of the general chemical formula I. In which Ar _{1 is} a diphenyl ether group, Ar? a benzene ring. Ar ₃ denotes a diphenyl ether group and Ar ₄ denotes a benzophenone group.

The polyimide resin layer 24 can also be selectively etched chemically instead of with an oxygen plasma will. After applying the prepolymer solution and a heat treatment of the wet coating voi one hour at 160 ° C, the solvent is de Coating largely evaporated without being there

Polyimide is already fully cured. In this condition, which has not yet condensed, the layer can be easily etched with 40 to 80% by weight hydrazine solution. The polyimide is completely cured by a subsequent heat treatment of one hour each at 200 ^° C. and then 300 ^° C. and has the same properties as the polyimide resin layer which has been hardened through in one process and etched by the oxygen plasma.

As an electrode material in connection with the ι ο polyimide resin layer, in addition to aluminum other materials, especially titanium, molybdenum, gold, silver, copper, chromium and platinum as well Alloys of these metals can be used.

The polyimide resin layer preferably has a thickness of 2 to 15 μm. For the sake of mechanical Strength when making the wire connections, the layer thickness should be at least 2 μπι and for reasons of Etchability should not be more than 15μΐη. the end economic considerations will be a thickness for the polyimide resin layer in the range of 3 to 10 μπι preferably complied with. The reason for this is the fig. 6 can be found. In automatic production is the production yield of the wire connection stage with a polyimide resin layer of 2 μπι only 50%, while it is already practically 100% with a layer thickness of 3 μm.

Instead of the aminosilanes described above as adhesion promoters, epoxysilanes can also be used be, preferably /? - (3,4-Epoxycyclo-

hexyl) ethyl trimethoxysilane and γ-glycidoxypropyl trimethoxysilane.

To prove the improved temperature behavior of the electrical characteristics of semiconductor components With the polyimide resin according to the invention, two series of Planar transistors of the structure shown in Figure 2 are produced. Series A specimens have one Polyimide layer with components of the formula II, while test objects of a series B have a polyimide resin layer with assemblies of the following formula included:

The current amplification factors of the test items are measured, i.e. the ratio of the collector current to the base current. The samples identically prepared in the manner described are initially at room temperature, then after a heat treatment of 60 minutes at 35O ⁰ C, then after a subsequent heat treatment of 10 minutes at 450 ⁰ C and finally by a subsequent heat treatment of 3 min at 500 ⁰ C measured. The corresponding values for specimens A according to the invention are 58%, 58%, 60% and 59%. The comparison values for test items B are 57%, 57%, 18% and 8%. The results show that the semiconductor component of the invention can, if necessary, also be wired at 500.degree. C., while temperatures of at most 300 to 350.degree. C. should be used for wiring in the case of the comparative component.

Moreover, polyimide resin layers were at the two mentioned μιτ in a layer thickness of 1 per the breakdown voltages at room temperature ge measured after the samples were heat treated respectively for 5 h at 250, 350 400 and 450 ⁰ C. The impact strengths for the polyamide resin layers as they are used in the semiconductor component of the invention are 420, 425, 41C, 390 and 340 in units of V / μm. The same values for the comparative test specimens are 260, 280, 285, 200 and 50.

For this purpose 4 sheets of drawings

Claims (1)

Patent claims: 1. Semiconductor component with an SKV layer lying on the surface of the semiconductor body and a protective layer made of a polyimide resin with assemblies of the general structure