JPH03276627A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Summary) With regard to pattern formation on a semiconductor substrate or a thin film formed on the substrate, the purpose of this invention is to completely remove the resist on the pattern formation surface. The step of coating the thin film formed on the substrate with a resist and forming a pattern by photolithography is a step of providing an intermediate layer between the substrate or the thin film and the resist that can be removed by etching with a higher selectivity than the substrate or the thin film. a step of selectively exposing and developing the resist to form a resist pattern; a step of selectively etching the intermediate layer and the substrate or thin film using the resist pattern as a mask; and a step of selectively etching the intermediate layer and the substrate or thin film using the resist pattern as a mask; A method of manufacturing a semiconductor device is characterized in that it includes at least a step of removing.

(Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor device in which no resist remains during pattern formation.

Due to the need to process large amounts of information at high speed, information processing equipment is becoming smaller and larger in capacity.In response to this, the semiconductor devices that make up the main body of the equipment are becoming more integrated, leading to LSI and VLSI. It has been put into practical use.

In the manufacture of all semiconductor elements, including these semiconductor devices, techniques such as thin film formation technology, photo-etching technology (photolithography or electron beam lithography), and impurity injection technology are used on semiconductor substrates.

Next, semiconductors include simple semiconductors such as silicon (Si), gallium arsenide (GaAs), and indium phosphide (Indium phosphide).
There are compound semiconductors represented by P), but LSI and V
Integrated circuits such as LSI are manufactured using Si substrates in most cases.

As a method for forming a thin film pattern, when a metal such as aluminum is used to form a wiring pattern, a sputtering method or a vacuum evaporation method is used, and when poly-Si is used, a vapor phase growth method (abbreviated as CVD method) is used. In addition, silicon dioxide (5i(h)) and silicon nitride (5i
sN4) is used, but these are all made by CVD method.

The thin film thus formed on the substrate or the substrate itself is then selectively etched using photolithographic technology to form wiring patterns with fine line widths and via-holes connecting upper and lower wiring layers. A trench is also formed in the substrate.

[Conventional technology]

As described above, in manufacturing a semiconductor device, a semiconductor substrate (hereinafter simply referred to as a substrate) or an insulating film or a conductive film is formed thereon, and a pattern is formed on this using photolithography.

In other words, a resist is coated on a substrate or a thin film, and when the resist is a "negative type", the light irradiated area is insoluble in the developer, and when it is a "positive type", it is soluble, so a resist pattern is created. This resist pattern is used as a mask to perform dry etching or wet etching to etch the substrate or the thin film on the substrate, and then the resist used as the mask is removed by dissolving it using a solvent or is subjected to plasma treatment. It is removed by this.

Here, the plasma treatment is performed using oxygen (0□) plasma and is called ashing (iodination treatment).

However, even with such a removal method, there are cases where sufficient removal is not possible, and in such cases, impurity ions, particularly sodium (Na) ions, contained in the resist contaminate the surface layer and cause problems such as increased leakage current. There is a problem that electrical characteristics are significantly deteriorated.

Therefore, it is necessary to completely remove the resist after pattern formation, but this is often not sufficient, and countermeasures are required.

[Problems to be Solved by the Invention] As a method for forming fine patterns in the manufacturing process of semiconductor devices, etching is performed on a substrate or a thin film formed on a substrate using a resist pattern prepared in advance as a mask to form a fine pattern. After that, the resist pattern is removed.

However, if this removal is insufficient, so-called Na contamination occurs, resulting in a significant decrease in reliability, which is a problem to be solved.

(Means for Solving the Problems) The above problem is that the process of coating a semiconductor substrate or a thin film formed on a substrate with a resist and forming a pattern by photolithography is a process in which a semiconductor substrate or a thin film formed on a substrate is coated with a pattern between the substrate or the thin film and the resist. Alternatively, there is a step of providing an intermediate layer that can be removed by etching with a higher selectivity than the thin film, a step of selectively exposing and developing the resist to form a resist pattern, and using this resist pattern as a mask, selecting the intermediate layer and the substrate or thin film. This problem can be solved by configuring a semiconductor device manufacturing method characterized by including at least the step of etching and the step of removing the resist used as a mask and the intermediate layer.

(Function) The present invention eliminates any residual resist by providing an intermediate layer that can be etched with a high selectivity to the substrate or thin film between the substrate or FR film on which a fine pattern is to be formed and the resist. It is.

In other words, an intermediate layer is prepared using a material that is more easily soluble in a specific solvent than the substrate or thin film, and a resist pattern formed thereon is used as a mask for dry etching.After the pattern is formed, the intermediate layer is dissolved with a solvent. This will allow you to completely remove the resist on top.

Here, the intermediate layer is phosphosilicate glass (abbreviated as PsG),
Borosilicate glass (BSG), borophosphosilicate glass (BP)
SG), etc., and the intermediate layer made of these materials is a 5% hydrofluoric acid (liver) aqueous solution, phosphoric acid/nitric acid (H2PO), etc.
It can be easily dissolved and removed using a mixed solution (&Il ratio: 100:2).

Note that metals such as Af and gold (Au) and insulators such as SiO□+513N4 can be considered as constituent materials for the thin film, but even in the case of 5iOz, which easily dissolves in the liver, the etching rate of the above glass material is approximately 10. twice as large, so m
Dissolution of W can be suppressed to an extremely low level.

Next, after removing the intermediate layer by straining, it is necessary to thoroughly wash with water to remove the solvent component, and then heat in an inert atmosphere such as nitrogen (N2) to remove the adsorbed water. It is.

〔Example〕

A case in which the present invention is applied to the formation of source and train electrodes in the manufacturing process of a MOS IC will be explained as follows.

After covering the element forming area of the Si substrate l with a Si:+N4 film, wet oxidation was performed at 1000°C to a thickness of approximately 6000°C.
After forming the field oxide film 2, the Si substrate 1 was immersed in hot HPO,+ to remove the 5isNa film.
A gate oxide film 3 having a thickness of approximately 300 mm was formed in the element formation region by dry oxidation using carbon. (Above Figure 1 A) Next,
The Si substrate 1 is set in a vapor phase growth apparatus, heated to 920''C in a phosphorus bromide (PBr+) gas atmosphere, and a PSG film 4 with a thickness of approximately 300 mm is deposited on the substrate. (See Figure B) Next, after coating the resist 5 on this substrate, RIE was performed using methane trifluoride (CHF3) as an etchant to form the PSG film 4 and gate oxide film 3. (See C in the same figure) Next, the Si substrate was immersed in boiling 12 SO to dissolve and remove the resist 5, and then immersed in a 2% HF aqueous solution for 40 seconds to remove the PSG film 4. , After thorough cleaning treatment with pure water, it was heated at 600° in a dry nitrogen (N2) atmosphere.
The water was removed by heating at C.

(The above is D in the same figure) By taking such a step, it was possible to obtain a gate oxide film 3 free from Na contamination.

〔Effect of the invention〕

By implementing the present invention, it is possible to eliminate residual resist on the substrate to be processed in the manufacturing process of semiconductor devices,
Thereby, the reliability of the semiconductor device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a MOS IC manufacturing process to which the present invention is applied. In the figure, 1 is a Si substrate, 2 is a field oxide film, and 3 is a Si substrate.
4 is the gate oxide film, 4 is the PSG layer, 5 is the resist, and 6.6' is the electrode formation area.

Claims (1)

[Claims] A step of coating a semiconductor substrate or a thin film formed on the substrate with a resist and forming a pattern by photolithography includes a step of forming a pattern between the substrate or the thin film and the resist at a higher temperature than the substrate or the thin film. a step of providing an intermediate layer that can be removed by etching with a selectivity; a step of selectively exposing the resist to light and then developing it to form a resist pattern; and a step of selectively etching the intermediate layer and the substrate or thin film using the resist pattern as a mask. A method for manufacturing a semiconductor device, comprising at least the following steps: and a step of removing the resist used as the mask and the intermediate layer.