JPH09106938A - Method for manufacturing semiconductor device - Google Patents

Abstract

Kind Code: A1 A method for manufacturing a semiconductor device is provided, which is capable of patterning a resist coated on the surface of a semiconductor substrate easily and with high dimensional accuracy. A resist (4) is irradiated with light (1) through a mask (2) to generate a functional group or compound having active hydrogen in an exposed portion (3). A silicon compound having a silyl group is supplied to the resist surface 4a to substitute active hydrogen of the functional group or compound with a silyl group, and the surface 3a of the exposed portion 3 is selectively selected with respect to the surface 13a of the unexposed portion 13. Silylation.
The resist surface 4a is irradiated with oxygen plasma to selectively change the surface 3a of the exposed portion 3 to be hydrophilic with respect to the surface 13a of the non-exposed portion 13. A silicon oxide film 12 is selectively formed on the hydrophilic surface 3a of the exposed portion 3 with respect to the surface 13a of the non-exposed portion 13 by a liquid phase growth method using an aqueous solution of hydrofluoric silicic acid. Anisotropic dry etching is performed using the silicon oxide film 12 as a mask to form the resist 4
To process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More particularly, it relates to a method of patterning a photoresist (for simplicity, referred to simply as "resist" throughout this specification) applied to the surface of a semiconductor substrate.

[0002]

2. Description of the Related Art With the recent miniaturization and high integration of semiconductor devices, there is a demand for a method of patterning a resist on a stepped surface of a semiconductor substrate with high dimensional accuracy.
Up to now, a multi-layer resist method (for example, described in "VLSI Manufacturing Technology", Nikkei BP (1989)),
DESIRE (Diffusion Enhanced SIlylating
REsist) process method (for example, described in "Short-wavelength photoresist material" Bushin Publishing (1988)).
Has been proposed.

In the above-mentioned multilayer resist method, first, as shown in FIG. 2A, a resist 107 is applied to the surface 105a of the semiconductor substrate 105. The surface 105 a of the semiconductor substrate 105 has a step 115, and the resist 107 has a surface (upper surface) 1.
It is assumed that it is applied thicker than the height dimension of the step 115 so that 07a becomes flat. Next, as shown in FIG. 2B, a silicon oxide film (hereinafter referred to as “SOG film”) 108 is formed on the entire surface by coating and baking.
Then, as shown in FIG. 7C, an upper layer resist 109 is applied thereon to a uniform thickness, and the upper layer resist 109 is applied.
Is processed into a predetermined pattern by photolithography. Next, as shown in FIG.
Using the as a mask, the SOG film 108 is etched. Same figure
As shown in (e), after removing the upper layer resist 109,
Dry etching is performed using the SOG film 108 as a mask to pattern the resist 107 on the substrate side (dry development). In this multi-layer resist method, the resist 107 on the substrate side is processed according to the pattern of the upper layer resist 109 having such a uniform thickness.
In comparison with the case where the photolithography is directly performed on the resist 7, the resist 10 due to the step 115 on the substrate surface 105a is formed.
It is possible to reduce the influence of the film thickness difference of No. 7 and the reflected light from the substrate surface 105a. Therefore, the dimensional accuracy of pattern processing can be improved to some extent.

The above-mentioned DESIRE process method is first shown in FIG.
As shown in (a), the surface 205a of the semiconductor substrate 205
Then, for example, a diazoketone-novolak-based positive resist 204 is applied. Surface 205a of semiconductor substrate 205
Has a step 215, and the resist 204 is applied thicker than the height dimension of the step 215 so that the surface (upper surface) 204a becomes flat. Subsequently, a mask 202 having a predetermined pattern is arranged to face the surface 204a of the resist 204, and the resist 204 is irradiated with light 201 through the mask 202. In the drawing, a well-shaped region in which dots are randomly dotted in the resist 204 indicates the exposed portion 203. This exposed portion 20
Indenecarboxylic acid is generated in 3 by the reaction with light 201. Next, as shown in FIG.
HMDS (hexamethyldisilazane, represented by the chemical symbol (Si (CH ₃ ) ₃ ) ₂ NH) having a silyl group is vapor-phase coated at about 180 ° C. Thereby, the resist 204
The active hydrogen of the phenolic hydroxyl group (“H” of —OH) generated in the exposed portion 203 of the above is replaced by the silyl group of this HMDS, and the surface 203a of the exposed portion 203 is exposed to the unexposed portion 2
The surface 213a of No. 13 is selectively silylated (silylation treatment). That is, the surface 203a of the exposed portion 203
Only, in this example forms a silylated region 206 having a _{-O-Si (CH 3) 3} . Next, as shown in FIG. 2C, RIE (reactive ion etching) showing anisotropy is performed using oxygen plasma to etch the resist 204. At this time, the silylated region 20
Since 6 exhibits resistance to oxygen plasma and acts as a mask, the region of the resist 204 not covered with the silylated region 206 (mainly the unexposed portion 213) is the substrate 20.
Etching is performed in the direction perpendicular to 5 and removed (dry development). In this DESIRE process method, the resist 204 is processed according to the pattern of the silylated region 206 thus formed on the surface 203a of the exposed portion 203, so that the substrate surface 20 is processed in the same manner as the multilayer resist method.
It is possible to reduce the influence of the difference in the film thickness of the resist 204 due to the step 215 of 5a and the reflected light from the substrate surface 205a. Therefore, the dimensional accuracy of pattern processing can be improved to some extent.

[0005]

However, in the above-described multi-layer resist method, as compared with the case where the photolithography is directly performed on the resist 107, the coating step of the SOG film 108, the photolithography step of the upper layer resist 109, and the SOG film are performed. There is a problem that the etching process of 108 is increased and the process becomes complicated. In particular, the dimensional shift must be controlled in each of the two photolithography processes (developing process), which is troublesome. In addition, the above DESIR
In the E process method, as shown in FIG.
Since the shape of 06 is thick in the central portion 206c and thin in the peripheral portion 206e, not only the region 214 not covered by the silylated region 206 but also the peripheral portion 206e of the silylated region 206 is directly under the dry developing process. Portion 215 is etched. Therefore, there is a problem that the dimensional accuracy of pattern processing of the resist 204 cannot be improved as expected. There is also a method of exposing the silylated surface to oxygen gas to form an oxide film on the silylated surface to enhance the etching resistance, but since it becomes thinner at the peripheral portion, the area directly below the peripheral portion is also etched.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a semiconductor device capable of patterning a resist applied on the surface of a semiconductor substrate easily and with high dimensional accuracy.

[0007]

In order to achieve the above object, a method of manufacturing a semiconductor device according to a first aspect is a method of manufacturing a semiconductor device in which a resist applied on the surface of a semiconductor substrate is patterned. And irradiating the resist with light through a mask arranged so as to face the surface of the resist, to generate a functional group or compound having active hydrogen in the exposed portion of the resist exposed to the light, A silicon compound having a silyl group is supplied to the surface of the resist, and the active hydrogen of the functional group or the compound is replaced with the silyl group of the silicon compound, so that the surface of the exposed portion is different from the surface of the unexposed portion. A step of selectively silylating and irradiating the surface of the resist with oxygen plasma,
A step of reacting a silyl group in the exposed portion with oxygen to selectively change the surface of the exposed portion into hydrophilicity with respect to the surface of the non-exposed portion; and a solution using an aqueous solution of hydrofluoric acid. A step of forming a silicon oxide film selectively on the surface of the non-exposed portion on the surface of the exposed portion that has changed to hydrophilic by a phase growth method; and a dry process showing anisotropy using the silicon oxide film as a mask. The method is characterized by including a step of processing the resist by performing etching.

In the method of manufacturing a semiconductor device according to the present invention, a silicon oxide film (hereinafter referred to as "LPD film") is formed only on the surface of the exposed portion of the resist by the liquid phase growth method using an aqueous solution of hydrofluoric silicic acid. To form. Since this LPD film is deposited on the surface of the exposed portion of the resist to a uniform thickness, dry etching exhibiting anisotropy is performed using the LPD film as a mask to process the resist in the LP process.
The portion immediately below the peripheral edge of the D film is not etched. Therefore, the resist is patterned with higher dimensional accuracy than the conventional one. Further, in this method of manufacturing a semiconductor device, the developing process is performed only once, so that the process is simplified as compared with the conventional multilayer resist method (the developing process is performed twice).

A method of manufacturing a semiconductor device according to a second aspect is the method of manufacturing a semiconductor device according to the first aspect,
The silicon compound is hexamethyldisilazane in a gas state.

In the method of manufacturing a semiconductor device according to the present invention, since the silicon compound is hexamethyldisilazane in a gas state, the hexamethyldisilazane in a gas state is formed on the semiconductor substrate at a temperature of 160 to 180 ° C. By supplying to the surroundings, the surface of the exposed portion of the resist is easily silylated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a method for manufacturing a semiconductor device according to the present invention will be described in detail.

First, as shown in FIG. 1A, a quinone azide / phenol-based positive resist 4 is applied to the surface 5 a of the semiconductor substrate 5 in this example. There is a step (height dimension 1 μm or less) 15 on the surface 5 a of the semiconductor substrate 5, and the resist 4 is thicker than the height dimension of the step 15 and has a height of 1 to 2 μm so that the surface (upper surface) 4 a is flat. It shall be applied in a thickness.

A mask 2 having a predetermined pattern is arranged so as to face the surface 4 a of the resist 4, and the resist 4 is irradiated with light 1 through the mask 2. In the figure, a well-shaped region in the resist 4 which is randomly dotted indicates the exposed portion 3. Indenecarboxylic acid is generated in the exposed portion 3 by the reaction with the light 1.

Next, as shown in FIG. 1B, the surface of the resist 4 is heated at a temperature of about 160 to 180 ° C. for 2 to 3 times.
HMD as a silicon compound having a silyl group only for a minute
S (hexamethyldisilazane. Chemical symbol (Si (CH ₃ ))
₃ ) Represented by ₂ NH. ) In a vapor phase. This allows
The active hydrogen of the indenecarboxylic acid (“H” of —COOH) generated on the exposed portion 3 of the resist 4 is replaced with the silyl group of this HMDS so that the surface 3a of the exposed portion 3 becomes the surface 13a of the non-exposed portion 13. Selectively silylate (silylation treatment). In other words, only on the surface 3a of the exposed portion 3,
A silylated region 6 having —O—Si (CH ₃ ) ₃ is formed.

Next, as shown in FIG. 1 (c), oxygen plasma is applied to the surface 4 a of the resist 4 at a pressure of 3 mmTo.
rr, O ₂ flow rate 60 SCCM, microwave power 200
Irradiate only 10 Sec under the conditions of W and high frequency power 120 W. As a result, the silyl group of the exposed portion 3 is replaced with oxygen, and the surface 3a of the exposed portion 3 is selectively changed to be hydrophilic with respect to the surface 13a of the non-exposed portion 13. That is, the SiO-based film 11 is formed only on the surface 3a of the exposed portion 3. On the other hand, the surface 13a of the non-exposed portion 13 remains hydrophobic.

Next, as shown in FIG. 1D, non-exposure is performed on the surface 3a of the exposed portion 3 which has been changed to hydrophilic by a liquid phase growth method using an aqueous solution of hydrosilicofluoric acid containing Al. Selective with respect to the surface 13a of the portion 13, the thickness 500
An LPD film (silicon oxide film) 12 having a thickness of 1000 Å is formed. At this time, the LPD film 12 is deposited to a uniform thickness on the surface 3a of the exposed portion 3 which is hydrophilic in nature, while the surface 13a of the non-exposed portion 13 left hydrophobic remains. Is not deposited on.

After that, dry etching exhibiting anisotropy using the LPD film 12 as a mask, in this example, RIE (reactive ion etching) using oxygen plasma is performed to process the resist 4 (dry). developing). Since the LPD film 12 is deposited with a uniform thickness over the entire surface 3a of the exposed portion 3 (described above), in this step, the peripheral portion 12 of the LPD film 12 of the resist 4 is formed.
The portion directly below e is not etched. Therefore, the resist 4 can be patterned with higher dimensional accuracy than the conventional one. By etching the semiconductor substrate 5 or a film that may exist between the semiconductor substrate 5 and the resist 4 by using the resist 4 patterned in this way with high dimensional accuracy, the etching selection ratio can be increased.

Further, in this manufacturing method, since the developing step only needs to be performed once, the conventional multi-layer resist method (the developing step has two steps).
The process can be simplified as compared with

In this example, the surface 5a of the semiconductor substrate 5 is
A quinone azide / phenolic positive resist 4 is applied to the surface (step), and active hydrogen of indenecarboxylic acid (“H” of —COOH) generated in the exposed portion 3 of the resist 4 is changed to H.
The silylation treatment for substituting with the silyl group of MDS is performed (step), but the present invention is not limited to this. A diazoketone-novolak resin-based positive resist may be used as the above resist, and active hydrogen (—H of —OH) of the phenolic hydroxyl group generated in the exposed portion of this resist may be replaced by the silyl group of HMDS. Further, compounds other than HMDS can be used as the silicon compound having a silyl group.

[0020]

As is apparent from the above, in the method of manufacturing a semiconductor device according to the first aspect, since the LPD film is deposited on the surface of the exposed portion of the resist to have a uniform thickness, this LPD film is used as a mask. In the step of processing the resist by performing dry etching exhibiting the directionality, the portion immediately below the peripheral portion of the LPD film is not etched. Therefore,
The resist can be patterned with higher dimensional accuracy than the conventional one. Further, in this method of manufacturing a semiconductor device, the developing process is performed only once, so that the process can be simplified as compared with the conventional multilayer resist method (the developing process is performed twice).

In the method of manufacturing a semiconductor device according to the second aspect, since the silicon compound is hexamethyldisilazane in a gas state, the hexamethyldisilazane in a gas state is heated around the semiconductor substrate at a temperature of 160 to 180 ° C. The surface of the exposed portion of the resist can be easily silylated by supplying the above.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process flow of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a process flow of a conventional multilayer resist method.

FIG. 3 is a diagram showing a process flow of a conventional DESIRE method.

FIG. 4 is a diagram illustrating a problem of the conventional DESIRE method.

[Explanation of symbols]

 3 Exposed part 4 Resist 5 Semiconductor substrate 6 Silylation region 11 SiO-based film 12 LPD film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/302 A J

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device, comprising patterning a resist applied on the surface of a semiconductor substrate, the step of irradiating the resist with light through a mask arranged so as to face the surface of the resist, A step of supplying a silicon compound having a silyl group to the surface of the resist to selectively silylate the surface of the exposed portion receiving the light with respect to the surface of the non-exposed portion; and oxygen plasma on the surface of the resist. And reacting the silylated exposed portion with oxygen to selectively change the surface of the exposed portion to hydrophilic with respect to the surface of the non-exposed portion, and hydrogen silicofluoride. A step of forming a silicon oxide film selectively on the surface of the exposed portion that has changed to hydrophilic by a liquid phase growth method using an acid aqueous solution; Dry etching is performed exhibited anisotropy as a mask, a method of manufacturing a semiconductor device characterized by having a step of processing the resist. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the silicon compound is hexamethyldisilazane in a gas state.