JPH0120532B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for forming a heat-resistant resin film used in a semiconductor integrated circuit, and particularly to a method for forming a highly heat-resistant resin film that can withstand relatively high temperatures of about 500°C. It is.

(Prior Art) Conventionally, polyimide resin, heat-resistant photoresist, ladder silicon, or organic silicon materials have been used as such highly heat-resistant resin films, and the development of application technology to electron devices has been extremely remarkable.

For example, resin insulated multilayer wiring technology has been developed as a multilayer wiring technology to achieve high integration of LSIs, and high purity polyimide resin is generally used as the insulating material for these.

In addition to such polyimide resins, the use of the heat-resistant photoresist, ladder silicon, or organic silicon materials is also being studied for the purpose of increasing the integration density of LSIs, and in particular, the use of the above-mentioned polyimide resins and organic silicon materials is being investigated. Progress in development research is remarkable.

However, the above-mentioned polyimide resin loses weight when heat treated at about 450°C, and its heat resistance cannot be said to be sufficient at the heat treatment temperature of 500°C or higher required for the above-mentioned multilayer wiring process.

On the other hand, organic silicone resin has extremely high heat resistance.
For example, it has the property of being able to withstand heat treatment at around 1000℃, but it has a relatively thick film thickness, specifically 1 to 2 μm.
It is extremely difficult to form thick films.

In general, organic silicone resins tend to shrink and crack due to heat treatment, and can withstand practical use up to approximately 1000 Å, but the film thickness required for the above-mentioned LSI is 1 to 2 μm.
However, due to the crack, it is almost impossible to put it to practical use.

That is, polyimide resin is preferable in terms of sufficient film thickness, and organic silicon material is preferable in terms of heat resistance.

In addition to the above-mentioned physical properties, other electrical properties are also important for such resin films. For example, polyimide resin is thought to have a large movement of mobile ions mainly due to metal ions in the resin compared to other PSG films, and these mobile ions have the problem of corroding aluminum wiring patterns due to the so-called battery effect. Occur.

The above-mentioned PSG film contains phosphorus in SiO ₂ , and it is widely known that the presence of this phosphorus element prevents the movement of mobile ions such as Na and Cl.

Furthermore, the movement of such mobile ions within the resin film causes deterioration of the electrical properties of the resin film, and improvements in these are strongly desired.

(Object of the Invention) In view of this problem, the inventors of the present invention aimed to obtain a resin film with excellent heat resistance and sufficient thickness.
Furthermore, the present invention was completed after repeated studies regarding the passivation effect of the resin film, that is, the formation of a resin film having excellent properties such as low micro-leakage current.

That is, the present invention provides pyromellitic acid dianhydride, 3,3',4,4'-benzophenyltetracarboxylic acid dianhydride,
4,4'-diaminodiphenyl ether, 4,
A mixture of a polyimide resin precursor solution containing a reactant with 4'-diaminodiphenyl ether-3-carbonamide and a silicon compound solution containing phosphorus in advance is applied onto a silicon substrate and heated. This is a method for forming a heat-resistant resin film characterized by a treatment.

The present invention will be explained in detail below.

First, a case where a polyimide resin and an organic silicon material are generally used will be briefly explained. To form a film using polyimide resin, a polyamic acid solution, which is a polyimide precursor, is applied onto a silicon substrate using a spinner or the like. Here, the structure of polyamic acid is shown by the following formula.

Thereafter, by heat treatment at a temperature of about 200° C., the solvent evaporates, and the polyamic acid undergoes dehydration and ring closure to become a polyimide of the following formula.

The polyimide resin film obtained in this way is
When heat treated in air (oxygen atmosphere), approximately 420
A gradual decrease in film weight and thinner film thickness is observed at temperatures between .degree. C. and 470.degree. C. (see, for example, Japanese Patent Publication No. 51-44871).

Next, organic silicon compounds are widely known as silica films, and their main component is, for example, silicon acetate dissolved in ethyl alcohol.
20875, 52-16488, etc.).

In the case of an organic silicon material, the above-mentioned silicon acetate solution is similarly applied onto a silicon substrate by spin coating and heated to about 400° C. in air (in an oxygen atmosphere), thereby converting it into a SiO ₂ film. The obtained SiO ₂ film can withstand heat treatment of, for example, 1000℃,
Since it can be etched with hydrofluoric acid, it can also be used as a mask for impurity diffusion, and its properties are the same as ordinary SiO ₂ films, but as mentioned above, it is prone to cracks.

On the other hand, the present invention uses a particularly limited pyromellitic dianhydride as described above, and 3,
Reactant of 3',4,4'-benzophenyltetracarboxylic acid dianhydride, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether-3-carbonamide A mixed solution of a polyimide resin precursor solution containing phosphorus and a silicon compound solution containing phosphorus in advance is applied onto a silicon substrate and heat-treated to form a Si-O-Si layer in the coating film. Since a resin film containing both the polyimide component and the polyimide component is formed, the above-mentioned heat resistance is significantly improved and high crack resistance is obtained.

Furthermore, electrical insulation properties of such an insulating film, specifically the magnitude of the above-mentioned microleakage current, are a problem, but the present invention can solve this problem by pre-containing phosphorous element in the organic silicon compound and forming the film. A silicon-polyimide film containing phosphorus could be formed, and the phosphorus has the effect of fixing mobile ions, making it possible to significantly reduce the above-mentioned leakage current.

Next, in the present invention, the organosilicon compound is
For example, the following formula [RnSi(OH) _4-o ] (wherein R is a monovalent hydrocarbon group, n is 1 to 0 including 0)
(an integer of 4) and additives (vitreous forming agents, organic binders, etc.) as the main component of alcohol,
It is dissolved in an organic solvent such as ester or ketone, and contains 20% by weight or less of the silicon compound.

In order to make such a silicon compound contain phosphorus, the above silicon compound [RnSi(OH) _4-o and a phosphorus compound] This is carried out by preparing in advance a solution dissolved in an organic solvent and mixing it with the above-mentioned polyimide precursor solution.

The phosphorus content is 1% to the silicon compound mentioned above.
A range of up to 25% is suitable.

Next, in the present invention, it is appropriate to heat the above-mentioned coating film coated on a silicon substrate at a temperature in the range of 80 to 500°C.

(Examples) The present invention will be described in detail below based on specific examples.

Example 1 As polyimide precursors, pyromellitic dianhydride, 3,3',4,4'-benzophenyl tetracarboxylic acid dianhydride, and 4,4'-diaminodiphenyl ether were used. , 4,4′-diaminodiphenyl ether-3-
A solution of the reactant (resin concentration 14.0%) in which carbonamide and N-methyl-2-pyrrolidone were dissolved.
and an organosilicon compound solution containing phosphorus as described above (for example, silicon acetate, SiO ₂ concentration 3%, phosphorus content 1 g/organosilicon solution 100 c.c.)
and 10 c.c. were prepared and mixed. The resulting mixture was spin-coated onto a silicon substrate using a spinner, and then the silicon substrate was heated at 100° C. for 1 hour.
As a result, it has a film thickness of 1 to 2 μm and contains Si containing phosphorus.
A resin film having an -O-Si structure and a polyimide structure was formed on a silicon substrate. When we investigated the heat resistance properties of this film, we found that it has heat resistance properties as shown in Figure 1.
Characteristic curves 1 and 2 shown by solid lines measured by TGA and DTA were obtained. What is the TGA characteristic here?
The weight of the resin is measured against time at 500℃ (in air).

Similarly, the heat resistance characteristics of the polyimide resin alone (hereinafter abbreviated as PI) are shown by curves 3 and 4.
Comparing the two, it is clearly recognized that in characteristic curves 1 and 3, the weight loss rate of the present invention is shifted to the longer time side than in PI3.

Next, the DTA characteristics indicate an endothermic or exothermic reaction to the temperature of the resin, and similarly comparing characteristic curves 2 and 4, the characteristics of the resin of the present invention are shifted to the long-term side compared to PI. That is, the exothermic reaction indicates a decomposition reaction of the resin, and the fact that the exothermic point shifts to the longer time side indicates that the resistance to temperature is correspondingly greater.

Next, FIG. 2 shows a comparison result of micro leakage current between the resin film of the present invention and the PI resin film. The characteristic values of the resin film of the present invention are shown by curve 1, and the characteristic values of the PI resin are shown by curve 2. P.I.
It has been found that while the leakage current of resin rapidly increases as the voltage increases, this is hardly observed in the resin film of the present invention.

Example 2 Example 1 above except that a mixture of polyimide precursor solution 22 c.c. and organosilicon compound solution 22 c.c. (phosphorous content 1 g/100 c.c. in organosilicon) was used.
The above-mentioned heat resistance and leakage current were examined in the same manner as in Example 1, and the results showed values equal to or higher than those of Example 1.

Example 3 Adding 0.1 g of phosphorus to the above organosilicon compound solution
The same procedure as in Example 1 was carried out except that the amount of addition was within the range of 5 g, and a film having properties equal to or better than those of Example 1 could be formed.

Example 4 The same procedure as in Example 1 was conducted except that silicon hydroxide was used instead of silicon acetate in Example 1, and it was confirmed that a film having properties equal to or better than those of the above examples could be obtained. Ta.

(Effects of the Invention) As explained above, the present invention can form a film having excellent heat resistance, coating resistance, and electrical insulation resistance on a silicon substrate, and is particularly useful for various insulating films and passivation films of ultra-high integrated circuits. It exhibits excellent effects when used in formation, and has extremely high industrial value.

[Brief explanation of drawings]

Figure 1 is a heat resistance characteristic diagram of the heat-resistant resin film of the present invention, Figure 2
The figure shows the electrical characteristics diagram.

Claims (1)

[Scope of Claims] 1. pyromellitic dianhydride; 3.
Reactant of 3',4,4'-benzophenyltetracarboxylic acid dianhydride, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether-3-carbonamide A method for forming a heat-resistant resin film, which comprises applying a mixture of a polyimide resin precursor solution containing phosphorus and a silicon compound solution containing phosphorus on a silicon substrate and heat-treating the mixture. 2. The method for forming a heat-resistant resin film according to claim 1, wherein the organic silicon compound solution contains silicon acetate dissolved in ethyl alcohol as a main component. 3 A mixture of the polyimide resin precursor solution and an organic silicon compound solution is applied onto a silicon substrate and heated to form Si-O-Si in the resin film.
A method for forming a heat-resistant resin film according to claim 1, which comprises forming and containing a structure. 4. The method of forming a heat-resistant resin film according to claim 1, wherein the organic silicon compound solution contains silicon hydroxide dissolved in ethyl alcohol as a main component.