JP2015005577A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology having a merit in reducing particles that can occur when a film is removed by etching.SOLUTION: A method of manufacturing a semiconductor device includes, a first step in which a member is prepared which has a step including a first upper surface and a second upper surface, being different in height from each other, and a connection surface which connects the first upper surface and the second upper surface, with the connection surface tilted to form a slope, a second step in which a film made from a material different from the member is formed on the first upper surface and the second upper surface as well as the slope of the member, and a third step for removing the member and the film in a region containing the slope is removed by etching.

Description

  The present invention relates to a method for manufacturing a semiconductor device.

  A pad portion is provided in the semiconductor device. In the case of the solid-state imaging device disclosed in Patent Document 1, a planarization layer, a color filter film, and an on-chip microlens are provided on the pad portion. In Patent Document 1, openings are formed in the on-chip microlens layer and the planarization layer so as to expose the pad portion.

JP 2003-229551 A

  In some cases, a semiconductor device is provided with a stepped portion such as a scribe region around the pad portion. When an opening is formed as in Patent Document 1, there is a possibility that particles are generated at this step.

  An object of the present invention is to provide a technique advantageous for reducing particles that may be generated when a film is removed by etching.

  One aspect of the present invention relates to a method for manufacturing a semiconductor device, and the method for manufacturing a semiconductor device includes a first upper surface, a second upper surface, the first upper surface, and the second upper surface having different heights. A first step of preparing a member having a step including a connection surface that connects the first and second surfaces, and forming the inclined surface by inclining the connection surface; and the first upper surface, the second upper surface, and the inclined surface of the member A second step of forming a film made of a material different from that of the member, and a third step of removing the member and the film in the region including the inclined surface by etching. .

  The present invention is advantageous for reducing particles that may be generated when the film is removed by etching.

The figure explaining the particle | grains which may arise in the case of an etching. , , , , 8A and 8B illustrate a reference example of a method for manufacturing a semiconductor device. FIG. 6 is a diagram for explaining an example of a method for manufacturing the semiconductor device according to the first embodiment. 8A and 8B are diagrams for explaining an example of a semiconductor device manufacturing method according to a second embodiment.

(Reference example)
First, a reference example will be described with reference to FIG. FIG. 1A shows a structure in which a film N (for example, a protective film) having a film thickness t of a material different from that of the member M is formed on the member M having the level difference h. The film N has a film thickness t on the upper surfaces m1 and m2 of the member M, but has a film thickness t ′ (t ′ is substantially equal to t + h) at the stepped portion. FIG. 1B shows a structure of the structure of FIG. 1A when the film N in the region R is removed by etching and then the member M in the region R is removed by etching. Since the film thickness t ′ of the film N is larger than the film thickness t of other parts at the stepped portion, a residue M ′ is generated. Thereafter, even if the member M is etched, the residue M ′ remains because the material is different from that of the film N. This is particularly noticeable in the process of forming a desired opening when the level difference h is large and the film N is etched at a lower etching rate than the member M. Since the residue M ′ can generate particles, the yield can be reduced. Next, an example of the solid-state imaging device IS _D as a reference example with reference to FIGS 2A~ Figure 2E, will be described more specifically the problem of the method of manufacturing the semiconductor device described with reference to FIG. Figure 2A (a) is a structure in the middle stage of the manufacturing process of the solid-state imaging device IS _D are schematically shown. The solid-state imaging device IS _D includes an imaging region 10, the electrode region 20 and the scribe region 30. 2A (b) shows a cross-sectional structure of the cut line AA ′ in FIG. 2A (a), and FIG. 2A (c) shows a cross-sectional structure of the cut line BB ′ in FIG. 2A (a). Show.

  In the imaging region 10, for example, a photoelectric conversion unit 110 is provided on a semiconductor substrate 100 (hereinafter, substrate 100). In the electrode region 20, an electrode 180 (pad) for reading a signal from the photoelectric conversion unit 110 is provided on the substrate 100 via the structure 120. The electrode 180 may include, for example, an electrode for inputting a control signal for driving the photoelectric conversion unit 110 and an electrode for power supply in addition to the electrode for outputting a signal from the photoelectric conversion unit 110. The structure 120 includes an insulating member and a wiring pattern provided in the insulating member. For example, the structure 120 may have a multilayer structure in which insulating layers and wiring layers are alternately provided. The electrode 180 can be provided, for example, in the uppermost layer of the plurality of wiring layers in the multilayer structure.

  A first organic film 130 is formed to cover the structure 120 and the electrode 180. Further, a color filter 140 is formed so as to cover a part of the imaging region 10 in the organic film 130. The color filter 140 can be provided corresponding to each photoelectric conversion unit 110 according to a Bayer array, for example. The second organic film 150 is formed so as to cover the organic film 130 and the color filter 140. The organic films 130 and 150 are provided using, for example, an acrylic resin and can function as a planarization layer.

  On the organic film 150, a microlens 160 is formed in the imaging region 10, and a lens member 165 is formed in the electrode region 20. These can be formed by depositing a photosensitive lens member 165 such as polyhydroxystyrene-based resin on the organic film 150 and then performing exposure processing and development processing using a photomask 800. For example, the lens member 165 can be formed into a lens shape so as to correspond to the photoelectric conversion unit 110 by the gradation mask pattern 800a in the imaging region 10, and the microlens 160 can be formed. Further, for example, in the electrode region 20, the exposure light is shielded by the light shielding mask pattern 800 b and the lens member 165 remains, whereas in the scribe region 30, the exposure light is irradiated and the lens member 165 can be removed. That is, a step is formed on the upper surface of the solid-state imaging device by the lens member 165. Since the above configuration is formed using a known semiconductor manufacturing process, detailed description of the manufacturing process is omitted here.

Thus, in the middle stage of the manufacturing process of the solid-state imaging device IS _D, considered is a case where a structure having a step on the upper surface is formed.

  After that, as illustrated in FIGS. 2B (a) to 2 (c), an inorganic material composed of an inorganic member such as silicon oxide or silicon nitride on the structure having the step (including the microlens 160). A film 170 may be formed. For example, the inorganic film 170 functions as a lens protective film when performing a subsequent process (opening for exposing the electrode 180), and also prevents reflection of light incident on the microlens 160. Can also function. 2B (a) to 2 (c) correspond to FIGS. 2A (a) to 2 (c) (the same applies to FIGS. 2C to 2E).

  Next, as illustrated in FIGS. 2C (a) to 2 (c), a resist pattern 210 for forming an opening exposing the electrode 180 may be formed on the inorganic film 170. Here, in the inorganic film 170, the resist pattern 210 is provided so that the portion of the electrode region 20 having the electrode 180 directly below and the portion of the scribe region 30 are exposed.

2D (a) to 2 (c), the inorganic film 170, the lens member 165, the organic film 150, and the organic film 130 are removed by etching using the resist pattern 210 as a mask, and the electrode 180 is formed. An opening may be provided to be exposed. Here, if the inorganic film 170 cannot be removed by this etching at the above-described stepped portion, a residue 173 may be generated. Here, the residue 173 shown in FIG. 2D (b) and the residue 173 shown in FIG. 2D (c) are formed on the upper surface of the substrate 100 as shown in FIG. 2D (a). It is shown that they are connected together in the direction of parallel planes. In FIG. 2D (b), the residue 173 is located at a distance above the structure 120, but may be located in contact with the upper surface of the structure 120. This residue 173, for example, a particle in removing the resist pattern 210 as shown in FIG. 2E (a) ~ (c) , may result in reduction in the yield in the manufacture of the solid-state imaging device IS _D.

(First embodiment)
Hereinafter, a method of manufacturing the solid-state imaging device IS _{1 according} to the first embodiment will be described with reference to FIG. 3A to 3F correspond to the cross-sectional views in the respective manufacturing steps of the solid-state imaging device IS ₁ corresponding to (b) in FIGS. 2A to 2E (that is, the cross-sectional structure of the cut line AA ′). This is shown schematically. First, as illustrated in FIG. 3 (a), in the same manner as the solid-state imaging device IS _D of Reference Example, the structure 120 on a substrate 100 in which the photoelectric conversion unit 110 is provided, the electrode 180, a first organic A film 130, a color filter 140, and a second organic film 150 are provided.

  Next, as illustrated in FIG. 3B, the lens member 165 is deposited on the organic film 150, and the microlens 160 is formed in the imaging region 10 using the photomask 800. For example, the lens member 165 can be formed into a lens shape so as to correspond to the photoelectric conversion unit 110 by the gradation mask pattern 800a in the imaging region 10, and the microlens 160 can be formed. On the other hand, for example, in the electrode region 20, the exposure light is blocked by the light shielding mask pattern 800 b and the lens member 165 remains, and in the scribe region 30, the exposure light is irradiated and the lens member 165 can be removed.

  Here, the lens member 165 in the scribe region 30 is removed so that the end of the lens member 165 has the inclined surface S in the vicinity of the boundary between the electrode region 20 and the scribe region 30. That is, the lens member 165 is removed so that the surface (connection surface) that connects the first upper surface and the second upper surface having different heights has an inclination. The inclined surface S can be formed using, for example, the gradation mask pattern 800c.

  As described above, in this step, a structure having a step on the upper surface is prepared, and the inclined surface S is formed by inclining the connection surface of the step. The preparation includes not only the case where a structure having the step is formed using a semiconductor manufacturing process, but also the case where a structure in which a step is already provided is prepared. The formation of S may be performed at the same time. The inclination of the inclined surface S may be 45 ° or less, for example.

  Next, as illustrated in FIG. 3C, an inorganic film 170 is formed on the structure having the step (including the microlens 160), and as illustrated in FIG. 3D. A resist pattern 210 is formed on the inorganic film 170. These may be performed in the same procedure as in the reference example.

Thereafter, as illustrated in FIG. 3E, the inorganic film 170, the lens member 165, the organic film 150, and the organic film 130 are removed by etching using the resist pattern 210 as a mask so that the electrode 180 is exposed. Is provided with an opening. Etching of the inorganic film 170 is performed by dry etching, for example. Specifically, the etching of the inorganic film 170 is performed by plasma etching using, for example, gas CF ₄ and Ar under the conditions of power 300 to 1500 W, pressure 30 to 230 mTorr, and time 40 to 120 seconds. sell. Etching of the lens member 165 and the organic films 150 and 130 is performed using, for example, gas O ₂ , N _2, and Ar under the conditions of power 300 to 1500 W, pressure 1000 to 2000 mTorr, and time 120 to 250 seconds. It can be done by etching.

As described above, the electrode 180 is exposed, then, as illustrated in FIG. 3 (f), the solid-state imaging device IS ₁ is obtained by removing the resist pattern 210.

According to the present embodiment, as illustrated in FIG. 3B, the inorganic film 170 is formed so as to cover the inclined surface S having a gentle inclination, so that the film thickness at the step portion of the inorganic film 170 is inclined. Is thinner than if it is steep. For example, when the inclination is 45 °, when the film thickness in the horizontal portion is t, the film thickness of the inorganic film 170 disposed on the inclined surface S (the film thickness in the step portion) is t × 2 ^{1 /} It is about ² . Therefore, according to the present embodiment, the residue 173 of the inorganic film 170 that can be generated by etching is reduced, which is advantageous in preventing the generation of particles.

(Second Embodiment)
Hereinafter, with reference to FIG. 4, describes a method for manufacturing the solid-state imaging device IS ₂ according to the second embodiment. In the first embodiment, the inclined surface S is formed using the gradation mask pattern. However, the method of forming the inclined surface S is not limited to this method, and the thermoplasticity of the lens member 165 is used as in the present embodiment. Then, the inclined surface S may be formed by heat treatment. First, as illustrated in FIG. 4A, in the same manner as the solid-state imaging device IS _D to IS ₁ of the reference example, a structure 120, an electrode 180, a first electrode on the substrate 100 on which the photoelectric conversion unit 110 is provided. The first organic film 130, the color filter 140, and the second organic film 150 are provided.

  Next, as illustrated in FIG. 4B, a lens member 165 is deposited on the organic film 150, and the microlens 160 is formed in the imaging region 10 using the photomask 800. For example, the lens member 165 can be formed into a lens shape so as to correspond to the photoelectric conversion unit 110 by the gradation mask pattern 800a in the imaging region 10, and the microlens 160 can be formed. On the other hand, for example, in the electrode region 20, the exposure light is blocked by the light shielding mask pattern 800 b and the lens member 165 remains, and in the scribe region 30, the exposure light is irradiated and the lens member 165 can be removed.

  Next, as illustrated in FIG. 4C, the microlens 160 and part of the lens member 165 are irradiated with ultraviolet light 500 to cause a crosslinking reaction. This step can be performed using, for example, a photomask 801 having a transmission pattern 801a that transmits light and a light shielding pattern 801b that blocks light. Thereby, a part of the microlens 160 and the lens member 165 has thermosetting properties. On the other hand, the ultraviolet light 500 is shielded from other portions of the lens member 165 (portions in the vicinity of the boundary between the electrode region 20 and the scribe region 30), and no crosslinking reaction occurs, so that a thermoplastic portion 168 is obtained.

  Thereafter, as illustrated in FIG. 4D, heat treatment is performed to thermally cure the lens member 165 and the microlens 160. On the other hand, the portion 168 has the inclined surface S because heat sag is generated by the heat treatment. 169 is formed.

  Next, as illustrated in FIG. 4E, an inorganic film 170 is formed on the structure having the step (including the microlens 160), and as illustrated in FIG. 4F. A resist pattern 210 is formed on the inorganic film 170. These may be performed in the same procedure as the reference example and the first embodiment.

Thereafter, as illustrated in FIG. 4G, the inorganic film 170, the lens member 165, the organic film 150, and the organic film 130 are removed by etching using the resist pattern 210 as a mask so that the electrode 180 is exposed. Is provided with an opening. Etching of the inorganic film 170 is performed by dry etching, for example. Specifically, the etching of the inorganic film 170 is performed by plasma etching using, for example, gas CF ₄ and Ar under the conditions of power 300 to 1500 W, pressure 30 to 230 mTorr, and time 40 to 120 seconds. sell. The inorganic film 170 may be etched by, for example, wet etching. Under such conditions, a sufficient selection ratio with respect to the lens member 165 and the organic films 150 and 130 can be obtained when the inorganic film 170 is etched. Etching of the lens member 165 and the organic films 150 and 130 is performed by dry etching, for example. Specifically, these etchings can be performed by plasma etching using gas O ₂ , N ₂ and Ar under conditions of power 300 to 1500 W, pressure 1000 to 2000 mTorr, and time 120 to 250 seconds. .

As described above, the electrode 180 is exposed, then, as illustrated in FIG. 4 (h), the solid-state imaging device IS ₂ is obtained by removing the resist pattern 210. According to the present embodiment, since the inorganic film 170 is formed so as to cover the inclined surface S with a gentle inclination, the residue 173 of the inorganic film 170 that may be generated by etching is reduced, which is advantageous in preventing the generation of particles. The same effects as in the first embodiment can be obtained.

  The above two embodiments have been described. However, the present invention is not limited to these embodiments, and can be appropriately changed according to the purpose, state, application, function, and other specifications. Can be done. For example, in each of the embodiments described above, the present invention is applied to the case where the inorganic film 170 made of an inorganic material is formed as a lens protective film on a structure having a step (an organic material member including the microlens 160). This has been illustrated and described. However, since the above-described residue 173 or particles can be generated if the material has a step in the middle of the manufacturing process and is made of different materials, the present invention is not limited to the configuration of each of the above-described embodiments. Moreover, although the case where the positive resist was used in the exposure processing and the development processing in each of the above-described embodiments was considered, the present invention is the same when the negative resist is used.

(Imaging system)
Moreover, the above embodiment described the solid-state imaging device contained in the imaging system represented by the camera etc. The concept of the imaging system includes not only a device mainly for photographing, but also a device (for example, a personal computer or a portable terminal) that is supplementarily provided with a photographing function. The imaging system may include a solid-state imaging device according to the present invention exemplified as the above-described embodiment, and a processing unit that processes a signal output from the solid-state imaging device. The processing unit may include, for example, an A / D converter and a processor that processes digital data output from the A / D converter.

Claims (9)

A member having a step including a first upper surface and a second upper surface having different heights and a connection surface connecting the first upper surface and the second upper surface is prepared, and the connection surface is inclined to be inclined. A first step of forming a surface;
A second step of forming a film made of a material different from that of the member on the first upper surface, the second upper surface, and the inclined surface of the member;
A third step of removing the member and the film in the region including the inclined surface by etching,
A method for manufacturing a semiconductor device. The inclined surface formed by the first step has an inclination of 45 ° or less.
The method of manufacturing a semiconductor device according to claim 1. The member is made of an organic material,
The film is made of an inorganic material,
The method for manufacturing a semiconductor device according to claim 1, wherein: The third step includes a step of etching the film, and a step of etching the member after the step of etching the film.
The method of manufacturing a semiconductor device according to claim 3. The step of etching the film is performed by dry etching,
The step of etching the member is performed by dry etching.
The method of manufacturing a semiconductor device according to claim 4. The member is composed of a photosensitive member,
In the first step, the inclined surface is formed by an exposure process and a development process using a gradation mask pattern.
The method for manufacturing a semiconductor device according to claim 1, wherein: The member is composed of a thermoplastic member,
In the first step, the inclined surface is formed by heat treatment.
The method for manufacturing a semiconductor device according to claim 1, wherein: The semiconductor device includes:
A photoelectric conversion unit provided on a semiconductor substrate; an electrode provided on the semiconductor substrate via an insulating member; and an electrode for reading a signal from the photoelectric conversion unit; and arranged corresponding to the photoelectric conversion unit, A solid-state imaging device having a microlens provided on the insulating member,
In the second step, the film is formed as a protective film for protecting the microlens,
In the third step, an opening is formed so that the electrode is exposed.
The method for manufacturing a semiconductor device according to claim 1, wherein: The method of manufacturing a semiconductor device according to claim 8, wherein in the second step, at least one of silicon oxide and silicon nitride is used for the film.

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