JPH0216007B2 - - Google Patents

Description

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

(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.

A case in which 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.
20825, 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.

(Problem to be Solved by the Invention) However, the above-mentioned polyimide resin loses weight when heat treated at about 450°C, and its heat resistance is not sufficient at the heat treatment temperature of 500°C or higher required for the above-mentioned multilayer wiring process. hard.

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 about 1000℃, but it has a relatively thick film thickness, specifically 1 to 2 μm.
It is extremely difficult to form a film with a thickness of m.

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 greater movement of mobile ions in the resin than other PSG films.

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.

The movement of such rotating ions in the resin film causes deterioration of the electrical properties of the resin film, and improvement thereof is strongly desired.

(Means for Solving the Problems) In view of the above problems, the present inventors have created 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 a polyimide resin precursor solution;
A solution of a phosphorus compound dissolved in a silicon compound solution represented by the general formula (RCOO) _o Si(OH) _4-o (wherein R is a monovalent hydrocarbon group and n is an integer from 0 to 4) This method of forming a heat-resistant resin film is characterized by applying a mixed solution onto a silicon substrate and subjecting it to heat treatment.

In the present invention, by mixing a polyimide precursor solution and the above-mentioned silicone solution containing phosphorus, applying the mixture onto a silicon substrate, and heating it, both the Si-O-Si component and the polyimide component are present in the coating film. A resin film containing the above is formed, thereby significantly improving the heat resistance and providing high crack resistance.

Usually, such insulating films have electrical insulation properties, specifically the magnitude of micro leakage current, which is a problem.
According to the present invention, a phosphorus-containing silicon-polyimide film can be formed by pre-containing a phosphorus element in the silicon compound described above and forming a film in the same manner. This reduces the current significantly.

In this invention, generally high molecular weight linear polyimide contains most dicarboxylic acid anhydrides and primary
A compound synthesized from grade diamine is used.

These diamines include m-phenylenediamine, p-phenylenediamine, 2,2-bis(4-aminophenyl)propane, 4,4'-methylene dianiline, benzidine, 4,4'-diaminodiphenyl sulfur. id, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, 3-methylheptamethylene diamine, 4 , 4-dimethylheptamethylene diamine, and dicarboxylic acid anhydrides include biromellitic anhydride, 2,
3,6,7-naphthalenetetracarboxylic anhydride, 3,3',4,4'-diphenyltetracarboxylic anhydride, 1,2,5,6-naphthalenetetracarboxylic anhydride, 2,2, 3,3-diphenyltetracarboxylic anhydride, thiophene-2,3,
4,5-tetracarboxylic anhydride, 2,2-bis(3,4-biscarboxyphenyl)propane anhydride, 3,4-dicarboxyphenyl sulfone anhydride, perylene-3,4,9,10 -Tetracarboxylic anhydride, bis(3,4-dicarboxyphenyl) ether anhydride, ethylenetetracarboxylic anhydride, 3,3',4,4'-benzophenonetetracarboxylic anhydride, etc. .

Polyamic acid is obtained by reacting these two components in a solvent, and the solvent exhibits sufficient activity to cause the reaction between the two components, strongly associates with the polymer and reaction reagent, and It must be able to hold an acid solution, specifically N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone,
Tetramethylurea, N-methylcaprolactam,
Examples include pyridine and aromatic hydrocarbons, which may be used alone or in combination.

In the present invention, the silicon compound is
The following formula, [(RCOO) _o Si(OH) _4-o ] (wherein R is a monovalent hydrocarbon group, n is 1 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 incorporate phosphorus into such a silicon compound, the above silicon compound [(RCOO) _o Si(OH) _4-o ] and a phosphorus compound are combined. 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 a polyimide precursor, a solution of a reactant (resin concentration 14.2%) in which diaminocarbonamide and acid dianhydride were dissolved in N-methyl-2-pyrrolidone solution
22 c.c. and a silicon compound solution containing phosphorus as described above (e.g. silicon acetate, SiO ₂ concentration 3%,
A total of 1 g of phosphorus content/10 c.c. of silicone solution (in 100 c.c.) was 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 had a film thickness of 1 to 2 μm and contained phosphorus.
A resin film having a 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 the heat resistance properties were TGA and TGA as shown in Figure 1.
Characteristic curve 1 shown as a solid line measured by DTA,
2 was obtained. Note that TGA characteristics are 500℃
The weight of the resin (in the air) is measured against time.

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

Example 3 The same procedure as in Example 1 was carried out except that phosphorus was added in the range of 0.1 g to 5 g into the silicon compound solution, and a film showing characteristics equal to or better than those in Example 1 was formed. did it.

Example 1 was carried out in exactly the same manner as in Example 1 except that silicon hydroxide was used instead of silicon acetate, and it was confirmed that a film having properties equivalent to or better than those of the above-mentioned examples could be obtained.

(Effects of the Invention) As explained above, the present invention is capable of forming a film having excellent heat resistance, coating resistance, and electrical insulation resistance properties on a silicon substrate using a mixed solution of a polyimide resin and a phosphorus-containing silicon compound. Therefore, it is particularly effective when used in the formation of various insulating films and passivation films for ultra-highly integrated circuits, 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)

[Claims] 1 A polyimide resin precursor solution and a compound having the general formula (RCOO) _o Si(OH) _4-o (in the formula, R is a monovalent hydrocarbon group and n is an integer from 0 to 4). A heat-resistant resin comprising: a step of mixing the represented silicon compound solution with a solution of a phosphorus compound to obtain a mixed solution; a step of applying the mixed solution onto a silicon substrate; and a step of heat-treating the silicon substrate. How to form a film. 2 The polyimide resin precursor solution converts diaminocarbonamide and acid dianhydride into N-methyl-2
The method for forming a heat-resistant resin film according to claim 1, which is a solution having a resin concentration of 14.2% dissolved in a pyrrolidone solution. 3. The method for forming a heat-resistant resin film according to claim 1, wherein the heating is performed at 100° C. for 1 hour. 4. The method for forming a heat-resistant resin film according to claim 1, wherein the phosphorus compound is a compound represented by the formula: (wherein R is a hydrocarbon group). 5. The method for forming a heat-resistant resin film according to claim 1, wherein the solution of the silicon compound and the phosphorus compound is a solution using an organic solvent.