CN1198317C - Formation method of oxide film preventing photoresist remover from attacking - Google Patents

Abstract

A method for forming oxide film to prevent the corrosion of photoresist remover features that nitrogen-contained element is injected into the surface layer of oxide film to form a surface layer with-O-N component on the oxide film on polysilicon, so resisting the corrosion of ammonium hydroxide in photoresist remover.

Description

Formation method of oxide film preventing photoresist remover from attacking

technical field

The present invention relates to a method for forming an oxide film that prevents photoresist remover from being corroded, in particular to forming a surface layer with -O-N composition on the oxide film on polycrystalline silicon of semiconductor components, and the surface layer of the -O-N composition can be During the photoresist removal process, it resists the erosion of the oxide film by the ammonium hydroxide in the photoresist removal solution.

Background technique

In the front end process of semiconductors, an oxide film (hereinafter referred to as low-pressure oxide film) is often deposited on the polysilicon layer by low-pressure chemical vapor deposition (CVD) to protect the polysilicon layer. Among them, if the oxide film/polysilicon interface is flatter, the oxide film will have better characteristics such as low leakage current and high breakdown voltage, and the formation of a low-pressure oxide film on the polysilicon layer by low-pressure chemical vapor deposition can achieve the above-mentioned Requirements for flat oxide film/polysilicon interface. On the contrary, if the oxide film formed by thermal oxidation directly on the polysilicon layer consumes polysilicon atoms, the oxide film/polysilicon interface will be rough, and the oxide film will have characteristics such as high leakage current and low breakdown voltage.

Among them, especially in non-volatile memory components, the oxide film on polysilicon is often an important dielectric material. In order to maintain the reliability of the data stored in the memory device, the dielectric material must have characteristics such as low leakage current and high breakdown voltage. These characteristics are closely related to the flatness of the interface between the oxide film on the polysilicon and the polysilicon. Therefore, low-pressure chemical vapor deposition (LPCVD) is generally used for the oxide film on polysilicon, and SiH ₄ or TEOS is used as a precursor to deposit a low-pressure oxide film, which is used as a dielectric material for capacitors in non-volatile memory components.

However, the low-pressure oxide film is often removed during the photoresist removal process. Due to the composition of ammonium hydroxide (NH ₄ OH) contained in the photoresist stripper (stripper), it will erode the low-pressure oxide film and even further remove it. Low pressure oxide film, resulting in polysilicon layer exposure.

Therefore, how to not corrode or further remove the low pressure oxide film on the polysilicon layer during the removal of the photoresist becomes an important issue. Among them, there are mainly two possible solutions:

1. Silicon nitride (hereinafter referred to as low-pressure silicon nitride) is formed by low-pressure chemical vapor deposition (LPCVD) instead of low-pressure oxide film to resist ammonium hydroxide erosion.

2. Treat the surface layer of the low-pressure oxide film with N ₂ O, N ₂ or NH ₃ gas plasma, so that the surface layer of the low-pressure oxide film forms -ON components to resist the erosion of ammonium hydroxide in the photoresist removal solution.

However, the stress between the low-voltage silicon nitride and the polysilicon layer cannot be matched, which causes the problem of leakage current; while the low-voltage oxide film is treated with plasma, the surface layer will suffer from plasma damage.

Contents of the invention

The main purpose of the present invention is to provide a method for forming an oxide film that prevents photoresist removal solution from corroding, by injecting nitrogen-containing elements into the surface layer of the oxide film, the oxide film on polysilicon is formed to have -O-N composition The surface layer, in the photoresist removal process, achieves the purpose of resisting the erosion of ammonium hydroxide in the photoresist removal solution.

The object of the present invention is achieved like this: a kind of formation method of the oxide film that prevents photoresist removal solution from corroding, it is characterized in that: it may further comprise the steps:

(1) providing a substrate, the substrate has a polysilicon layer;

(2) depositing an oxide film on the polysilicon layer;

(3) Tempering the oxide film under a nitrogen-containing gas to form a surface layer with —O—N composition on the surface of the oxide film.

The substrate is a silicon substrate. The oxide film is formed by chemical vapor deposition. The nitrogen-containing gas includes N ₂ , NH ₃ or N ₂ O gas. The temperature of the tempering treatment is 650° C., and the time is 30-60 minutes.

The present invention also provides a method for forming a semiconductor device, characterized in that it comprises the following steps:

(1) Depositing an oxide film on a substrate with a gate;

(2) under nitrogen-containing gas, thermally tempering the surface layer of the oxide film to form a surface layer with -O-N composition on the surface of the oxide film;

(3) forming a photoresist layer pattern on the oxide film;

(4) etching the oxide film to define a compensation sidewall insulator on the surface of the gate;

(5) Using a photoresist remover, the photoresist pattern is removed.

After removing the photoresist pattern, further include the following steps:

A. Ions are implanted into the substrate to form source/drain extension regions;

B. Forming sidewall insulators on the compensation sidewall insulators on both sides of the gate;

C. Ions are implanted into the substrate to form source/drain regions.

The substrate is a silicon substrate. The gate includes a polysilicon gate and a gate oxide film. The oxide film is formed by chemical vapor deposition. The nitrogen-containing gas includes N ₂ , NH ₃ or N ₂ O gas. The ion implantation includes phosphorous, arsenic or boron ions. The temperature of the tempering treatment is 650° C. and the time is 30-60 minutes.

The method for forming an oxide film that prevents photoresist removal liquid erosion of the present invention can obtain an etching rate 1.2-1.5 times higher than that of an untreated oxide film, and there is no leakage current caused by the incompatibility of the stress with the polysilicon layer question.

The present invention uses nitrogen-containing gas as an atmosphere to carry out thermal tempering furnace tube treatment on the oxide film, the process cost is low, the etching rate of the oxide film can be increased, and the etching selectivity ratio is better.

Further description below in conjunction with preferred embodiments and accompanying drawings

Description of drawings

1 to 5 are schematic diagrams of the method for forming an oxide film that prevents photoresist remover from being corroded by the present invention.

Detailed ways

Referring to Fig. 1-shown in Fig. 5, the formation method of the oxide film that prevents photoresist removal liquid from corroding of the present invention, comprises the steps:

Referring to FIG. 1 , firstly, a substrate 10 is provided, on which a polysilicon gate 11 and a gate oxide film 12 have been formed. Then, using TEOS (tetra-ethyl-ortho-silicate) or silane (SiH ₄ ) as a precursor, a low-pressure chemical vapor deposition (LPCVD) process is used to form a deposited oxide film 13 (such as silicon oxide, with a thickness of about 300 angstroms) on the polysilicon gate 11.

The gate oxide film 12 is usually formed by a thermal oxidation process, such as a dry oxidation method, at a high temperature such as 900°C. The polysilicon gate 11 uses silane (SiH ₄ ) as the main reactant and is passed through It is formed by a low pressure chemical vapor deposition (LPCVD) process, and then the gate oxide film 12 and the polysilicon layer gate 11 are formed according to the definition of the photolithography process and etching technology.

Referring to FIG. 2, for the substrate 10 described in FIG. 1, a thermal annealing (anneling) process is implemented under a nitrogen-containing gas (such as N ₂ , NH ₃ and N ₂ O), so that the nitrogen element and the oxide film 13 Oxygen elements produce chemical bonds, so that the oxide film forms a surface layer 14 with -ON composition, and the thermal tempering time and temperature are about 30-60 minutes and 650°C respectively

Referring to FIG. 3 , a pattern of a photoresist layer 15 is defined on the surface layer 14 of the oxide film 13 on the polysilicon gate 11 by a photolithography process. Then, using the photoresist layer 15 as a mask, anisotropic etching is performed on the oxide film 13 and the surface layer 14 to form a compensation sidewall insulator (offset spacer) 16 on the surface of the gate 17 .

Referring to FIG. 4 , the photoresist pattern is then removed using a photoresist remover. Wherein, because the surface layer 14 of the oxide film 13 has -O-N composition, it can resist the erosion of ammonium hydroxide in the photoresist removal solution. Next, the ion implantation process is implemented by using the compensation sidewall material 16 as a mask, and arsenic (As) or phosphorus (P) ions are implanted into the substrate 10 described in FIG. 3 to form source/drain extensions. Region 18, where the concentration of implanted ions is not high, is mainly used to adjust the threshold voltage of the gate.

Referring to FIG. 5 , an oxide film (such as silicon oxide with a thickness of about 300 angstroms) is deposited on the substrate 10 shown in FIG. 4 by a low pressure chemical vapor deposition (LPCVD) process. Afterwards, anisotropic etching is performed on the oxide film, part of the oxide film and part of the compensation sidewall 16 are removed, and sidewall insulators 19' (spacers) are formed on the compensation sidewall insulators 16 on both sides of the gate 17, and then In the ion implantation process, arsenic (As) or phosphorus (P) ions are implanted into the substrate 10 to form source and drain regions 20 .

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any modifications and modifications made by those skilled in the art without departing from the spirit and scope of the present invention belong to the present invention. within the scope of protection of the invention.

Claims (13)

1, a kind of photoresist that prevents is removed the formation method of the oxide-film of liquid erosion, and it is characterized in that: it may further comprise the steps:

(1) provides a substrate with polysilicon layer;

(2) deposition one oxide-film is on polysilicon layer;

(3) under nitrogenous elemental gas, this oxide-film of temper forms in its surface and one to have-top layer of O-N composition.

2, the photoresist that prevents according to claim 1 is removed the formation method of the oxide-film of liquid erosion, and it is characterized in that: this substrate is a silicon base.

3, the photoresist that prevents according to claim 1 is removed the formation method of the oxide-film of liquid erosion, and it is characterized in that: this oxide-film is to form with chemical vapour deposition technique.

4, the photoresist that prevents according to claim 1 is removed the formation method of the oxide-film of liquid erosion, and it is characterized in that: this nitrogenous elemental gas comprises N ₂, NH ₃Or N ₂O gas.

5, the photoresist that prevents according to claim 1 is removed the formation method of the oxide-film of liquid erosion, and it is characterized in that: the temperature of this temper is 650 ℃, and the time is 30-60 minute.

6, a kind of method that forms semiconductor device, it is characterized in that: it may further comprise the steps:

(1) deposition one oxide-film is in the substrate with grid;

(2) under nitrogenous elemental gas, the described oxide-film of hot temper top layer one has to form in the surface of described oxide-film-top layer of O-N composition;

(3) form a photoresist layer pattern on described oxide-film;

(4) the described oxide-film of etching defines compensation lateral wall insulation thing in described gate surface;

(5) use photoresist to remove liquid, remove described photoresist pattern.

7, the method for formation semiconductor device according to claim 6 is characterized in that: after removing described photoresist pattern, more may further comprise the steps:

A, ion flow in the described substrate, form the source/drain elongated area;

B, formation one lateral wall insulation thing are on the compensation lateral wall insulation thing of described grid both sides;

C, ion flow in the described substrate, form regions and source.

8, the method for formation semiconductor device according to claim 6 is characterized in that: described substrate is a silicon base.

9, the method for formation semiconductor device according to claim 6 is characterized in that: described grid comprises polysilicon gate and gate oxidation films.

10, the method for formation semiconductor device according to claim 6 is characterized in that: described oxide-film is to form with chemical vapour deposition technique.

11, the method for formation semiconductor device according to claim 6 is characterized in that: described nitrogenous elemental gas comprises N ₂, NH ₃Or N ₂O gas.

12, the method for formation semiconductor device according to claim 6 is characterized in that: it is to comprise phosphorus, arsenic or boron ion that described ion injects.

13, the method for formation semiconductor device according to claim 6 is characterized in that: the temperature of described temper is that 650 ℃ and time are 30-60 minute.