JP2009188038A - Semiconductor device, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device having a structure with a sufficient pixel characteristic and allowing easy manufacture. <P>SOLUTION: The method includes a process for etching at least a metal film formed on an insulating film and obtaining metal wiring, and a process for etching a part of the insulating film with metal wiring as a mask. Etching of a part of the insulating film is that by plasma derived from a gas for treatment, which contains a chlorine gas and a chlorine compound gas under supply of high frequency power and under vacuum. The chlorine gas and the chlorine compound gas are used with a ratio of a flow rate of the chlorine compound gas to a flow rate of the chlorine gas set to two to five times in the manufacturing method of the semiconductor device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof. More specifically, the present invention relates to a semiconductor device effective for improving the sensitivity of a solid-state imaging device and a method for manufacturing the same.

  2. Description of the Related Art Semiconductor devices such as solid-state imaging elements have been increased in size and size due to the miniaturization of each pixel constituting the element. Therefore, when one pixel size is reduced, the amount of light entering the photodiode, which is the light receiving portion, formed on the surface of the object to be processed is inevitably reduced, and pixel characteristics such as sensitivity and light collection rate are deteriorated. There is.

  As a technique for improving the deterioration of the pixel characteristics, a metal wiring formed on the solid-state image sensor and serving to transmit an electrical signal, and an insulating film for insulating between the solid-state image sensor and other metal wiring are used. There is a method of thinning. However, when the metal wiring is made thin, there is a problem that the wiring resistance increases. In addition, the reduction in the thickness of the insulating film lowers the insulating function and increases the electric capacity between the wirings. This causes a decrease in the operating speed of the solid-state imaging device and an increase in power consumption.

  As another technique for improving the deterioration of the pixel characteristics, there is a technique for narrowing the width of the metal wiring. However, if the width of the metal wiring is narrowed, the wiring resistance increases, and mask pattern formation and etching processing for photomask formation become very difficult.

  Therefore, if the metal wiring is formed by vertically processing the metal film for forming the metal wiring and the insulating film under the metal film as much as possible, light scattering in the metal wiring that is the light guide path can be suppressed. The characteristics (particularly the light collection rate) can be improved. However, as disclosed in Japanese Patent Laid-Open No. 63-69988 (Patent Document 1), in conventional etching processing of metal wiring mainly composed of aluminum using plasma, the insulating film under the metal wiring is vertically processed. If this is attempted, side etching of aluminum constituting the metal wiring is likely to occur. In order to prevent side etching, it is desirable to reduce the flow rate of the chlorine gas used. However, if the chlorine gas is reduced, the vertical workability of the insulating film is lost.

Further, when an etching process is attempted with plasma, as disclosed in Japanese Patent Application Laid-Open No. 2005-72260 (Patent Document 2), a solid-state imaging device in which ultraviolet rays generated by the plasma are formed below the metal wiring and the insulating film. is irradiated to the silicon -SiO ₂ film in. The irradiated ultraviolet rays generate interface states, and as a result, pixel characteristics (particularly sensitivity) are degraded.

JP 63-69988 A Japanese Patent Laid-Open No. 2005-72260

  It is an object of the present invention to provide a method for manufacturing a semiconductor device having a structure with favorable pixel characteristics and easy manufacturing.

Thus, according to the present invention, the method includes a step of etching at least a metal film formed on the insulating film to obtain a metal wiring, and a step of etching a part of the insulating film using the metal wiring as a mask,
Etching of a part of the insulating film is etching by plasma derived from a processing gas containing chlorine gas and chlorine compound gas under supply of high-frequency power and under vacuum,
A method of manufacturing a semiconductor device is provided, wherein the chlorine gas and the chlorine compound gas are used at a ratio of the flow rate of the chlorine gas to the flow rate of the chlorine compound gas 2 to 5 times higher.

Furthermore, according to the present invention, a solid-state imaging device formed on a semiconductor substrate, an insulating film formed on the semiconductor substrate so as to cover the solid-state imaging device, and a metal wiring formed on the insulating film are provided. At least,
The insulating film includes an etched surface other than under the metal wiring and a side surface connecting the unetched surface and the etched surface, and the side surface has a taper angle of 85 to 88 ° with respect to the etched surface. A semiconductor device is provided.

  According to the present invention, by controlling the flow rate ratio between chlorine gas and chlorine compound gas, the processing shape of the insulating film under the metal wiring can be made close to vertical. As a result, light scattering in the metal wiring can be suppressed, and a semiconductor device having high pixel characteristics and a method for manufacturing the same can be provided.

Embodiments of the present invention will be described below with reference to the drawings. The scope of the present invention is not limited to the following embodiments.
(Embodiment 1)
The first embodiment will be described with reference to FIGS.
FIG. 1 is a configuration diagram of an etching apparatus, and FIG. 2 is a detailed sectional view of an object to be processed. Processing is performed as follows.

  First, two or more kinds of plasma processing gases are supplied into the vacuum vessel 101 from the source gas holding units 110 to 112 through the valves 107 to 109 and the gas flow rate control means 104 to 106. Next, plasma is generated by supplying AC power to the electrode 102 installed in the vacuum vessel 101. The AC power is supplied from the AC power supply 115 and / or 117. The AC power is supplied from the AC power supply 115 side via the matching unit 116, and is supplied from the AC power source 117 side via the matching unit 118 and the loop antenna 119.

  A workpiece 103 is placed on the electrode 102. As shown in FIG. 2, the object 103 has at least one type of metal film and a desired mask pattern 209 formed on the surface thereof on at least one type of insulating film 204. In the present invention, the ratio of the chlorine gas flow rate to the chlorine compound gas flow rate is 2 to 5 times during the etching process of the insulating film 204.

The vacuum vessel 101 is made of aluminum (Al). It is desirable that the inner surface of the vacuum vessel 101 be protected with a material that is less contaminated with metal and less consumed by plasma. For example, it may be protected with alumina (Al ₂ O ₃ ) by alumite treatment. The inner surface of the vacuum vessel 101 may be protected by a ceramic material such as yttria (Y ₂ O ₃ ), quartz (SiO ₂ ), aluminum nitride (AlN), or silicon carbide (SiC), or Si.

The electrode 102 preferably uses a combination of a highly conductive metal and an insulating film. For example, a material obtained by attaching a polyimide film to a base material made of aluminum can be used. Alternatively, a base material made of copper and sprayed with Al ₂ O ₃ may be used.
As the object 103 to be processed, for example, a material mainly composed of silicon (Si) can be used.

Reference numerals 104 to 106 denote gas flow rate control means. In FIG. 1, a configuration in which three kinds of gases can be introduced into the vacuum vessel 101 by independently controlling the flow rates is adopted. Depending on the number of gases to be used, the gas flow rate control means may be increased or decreased. The gas flow rate control means is not particularly limited as long as the gas flow rate can be controlled. For example, HORIBA STEC SEC-Z500 mass flow controller can be used. Besides this, a float type flow meter may be used. Reference numerals 107 to 109 denote valves for closing the gas flow path when each gas is not used. Reference numerals 110, 111, and 112 denote raw material gas holding units, which hold chlorine gas (Cl ₂ ), boron trichloride (BCl ₃ ), and trifluoromethane (CHF ₃ ), respectively, in FIG. In the present invention, it is sufficient that at least chlorine gas and chlorine compound gas are contained. In some cases, the source gas may be diluted by adding argon gas (Ar) or helium (He) gas.

  Reference numeral 113 denotes an evacuation unit, and the specific configuration thereof is not particularly limited. In FIG. 1, a turbo molecular pump and a dry pump connected in series are used. Reference numeral 114 denotes a gas pressure control means, and the gas introduced into the vacuum vessel 101 by the gas flow rate control means 104 to 106 is used to control the effective exhaust speed of the vacuum exhaust means 113 so that the inside of the vacuum vessel 101 has a desired pressure. Is controlling.

  115 can output AC power having a frequency of 13.56 MHz and uses an AC power source with an output impedance of 50Ω. In addition to the AC power source of 13.56 MHz, an AC power source having a frequency such as 380 kHz or 27.12 MHz may be used. Reference numeral 116 denotes a matching unit. For example, a matching unit capable of converting the input impedance inside the vacuum vessel 101 into the output impedance of the AC power supply 115 can be used. In FIG. 1, the matching unit 116 that can convert the input impedance inside the vacuum vessel 101 into the output impedance 50Ω of the AC power supply 115 is used.

117 can output AC power having a frequency of 2 MHz, and uses an AC power source with an output impedance of 50Ω. The frequency of the AC power source 117 is desirably different from the frequency of the AC power source 115. In addition to the 2 MHz AC power supply, an AC power supply having a frequency such as 13.56 MHz or 27.12 MHz may be used. 118 is a matching unit, 119 is a loop antenna, and 120 is a dielectric plate made of, for example, Al ₂ O ₃ . As the matching unit 118, for example, one that can convert the input impedance of the loop antenna 119 to the output impedance of the AC power source 117 can be used. In FIG. 1, as the matching device 118, a device capable of converting the input impedance of the loop antenna 119 into the output impedance 50Ω of the AC power source 117 is used. The loop antenna 119 radiates electromagnetic waves into the vacuum vessel 101 through the dielectric plate 120 and excites inductively coupled plasma inside the vacuum vessel 101. FIG. 1 shows an inductively coupled plasma etching apparatus using a loop antenna. A capacitively coupled plasma etching apparatus, a magnetron plasma etching apparatus, a microwave plasma etching apparatus, an electron cyclotron resonance plasma etching apparatus, or the like is used. It doesn't matter.
A detailed cross-sectional view of the workpiece 103 is shown in FIG. This object 103 is an example, and various modifications are possible.

201 is a silicon wafer, and its size is not particularly limited. In FIG. 2, a wafer having a diameter of 200 mm and a thickness of 0.625 mm is used. Reference numeral 202 denotes a solid-state image sensor section formed on the silicon wafer surface. Although a CMOS solid-state image sensor is formed in FIG. 2, a CCD type or other solid-state image sensor may be used. Reference numeral 203 denotes a photosensitive portion of the solid-state image sensor unit 202, which is a part that converts light from the surface into an electrical signal. In FIG. 2, a photodiode is formed in the photosensitive portion 203, but the present invention is not limited to this. Reference numeral 204 denotes an insulating film, and reference numerals 205 to 207 denote metal films. 204 is for electrically insulating the metal films 205 to 207 and the solid-state imaging device. In FIG. 2, the insulating film 204 is a silicon dioxide (SiO ₂ ) film to which boron (B) and phosphorus (P) are added, which is formed by a chemical vapor deposition (CVD) method. The insulating film 204 may be formed by a chemical vapor reaction deposition (PE-CVD) method using a plasma reaction. Further, a SiO ₂ film to which B and P are not added, or a SiO ₂ film containing either B or P may be used.

  In FIG. 2, 205 and 207 are metal films mainly composed of titanium nitride (TiN). The metal films 205 and 207 may be a single TiN material, or may be a laminated structure in which TiN is formed on titanium (Ti), or a material such as tantalum (Ta). In FIG. 1, 206 is a metal film formed by physical vapor phase (PVD) method using an alloy containing aluminum (Al) as a main component and Cu (0.5%) added. As a material other than TiN, an Al / Si or Al / Si / Cu alloy may be used. The metal films 205 to 207 have a function of transmitting the photoelectric conversion signal and the control signal of the solid-state image sensor unit 202 via the connection unit 208. The connecting portion is made of, for example, a metal material whose main component is tungsten (W).

Reference numeral 209 denotes a photoresist film as a mask pattern for etching the metal films 205 to 207 into a desired wiring, and can be formed by resist film coating, exposure, and development processing. Although a photoresist film is used in FIG. 1, an SiO ₂ film may be used instead of the photoresist film.

FIG. 2 shows an example of etching the first metal film of the solid-state image sensor unit 202. Needless to say, the same applies to the etching of the second and subsequent metal films.
As the first stage of etching the metal films 205 to 207 with the apparatus of FIG. 1, the metal films 206 to 207 are etched under the plasma condition A, and as the second stage, the metal film 206 is etched under the plasma condition B. Then, as a third stage, the insulating film 204 is over-etched under the plasma condition C, so that a short circuit between the metal wirings formed by etching in the first and second stages can be prevented. An example of plasma conditions A to C will be described below.

Plasma condition A is set as follows. The flow rate of the mixed gas of Cl _2, BCl ₃ and CHF _3, the gas flow rate control means 104 to 106, respectively 60 sccm (standard cubic centimeters per minute), 35 sccm, set to 10 sccm. The mixed gas is introduced into the vacuum container 101, and the internal pressure of the vacuum container 101 is set to 10 mTorr using the vacuum exhaust means 113 and the gas pressure control means 114. AC power supplies 115 and 118 are set to 800 W and 115 W, respectively.

Plasma condition B is set as follows. The flow rate of the mixed gas of Cl ₂ and BCl ₃ is set to 60 sccm and 35 sccm by the gas flow rate control means 104 to 105, respectively. CHF ₃ gas closes valve 109 and is not used. The mixed gas is introduced into the vacuum container 101, and the internal pressure of the vacuum container 101 is set to 10 mTorr using the vacuum exhaust means 113 and the gas pressure control means 114. AC power supplies 115 and 118 are set to 800 W and 150 W, respectively.

Plasma condition C is set as follows. The flow rate of the mixed gas of Cl ₂ and BCl ₃ is selected from Cl ₂ = 30 sccm, 40 sccm, 50 sccm, and BCl ₃ = 10 sccm, 20 sccm, 30 sccm, respectively, by the gas flow rate control means 104 to 105, thereby setting a total of nine ways To do. CHF ₃ gas closes valve 109 and is not used. The mixed gas is introduced into the vacuum container 101, and the internal pressure of the vacuum container 101 is set to 10 mTorr using the vacuum exhaust means 113 and the gas pressure control means 114. AC power supplies 115 and 118 are set to 800 W and 100 W, respectively.

  FIG. 3 is an example of a detailed cross-sectional view after etching the object to be processed of FIG. 301 is an insulating film, and 302-304 are metal films. It is processed into a desired wiring pattern by etching. The photoresist film that is the mask pattern is removed by ashing. Reference numeral 301 is for electrically insulating the metal wiring films 303 to 304 and the underlying solid-state imaging device. Electrical insulation between the metal wirings is ensured by performing sufficient over-etching under the plasma condition C. Reference numeral 305 denotes an etching angle of the insulating film 301. Other components are the same as those in FIG.

FIG. 4 shows an example of the flow rate dependence of the mixed gas of Cl ₂ / BCl ₃ under the plasma condition C of the etching angle. From FIG. 4, when both the Cl ₂ flow rate and the BCl ₃ flow rate are increased, the overetch angle tends to increase. FIG. 5 shows an example of the dependency of the etching angle on the Cl ₂ / BCl ₃ flow rate ratio. FIG. 5 shows that the over-etch angle tends to increase as the Cl ₂ / BCl ₃ flow rate ratio increases.

FIG. 6 shows an example of the dependency of the signal / noise ratio (S / N ratio) of the solid-state imaging device on the flow rate of the mixed gas of Cl ₂ / BCl _{3 under} the plasma condition C. From FIG. 6, when both the Cl ₂ flow rate and the BCl ₃ flow rate are increased, the S / N ratio tends to increase.

FIG. 7 shows an example of the relationship between the flow rate ratio of Cl ₂ / BCl ₃ and the S / N ratio based on the results of FIG. From FIG. 7, it can be seen that there is a correlation between the flow rate ratio of Cl ₂ / BCl ₃ and the S / N ratio. When the flow rate ratio of Cl ₂ / BCl ₃ is less than 2, the S / N ratio is lowered. That is, it has been clarified that the metal wiring etching process capable of improving the sensitivity of the solid-state imaging device can be performed by setting the flow rate ratio of Cl ₂ / BCl ₃ to 2 to 5.

(Embodiment 2)
The second embodiment will be described with reference to FIG.
In Embodiment 2, Cl ₂ gas, carbon tetrachloride (CCl ₄ ), and trifluoromethane (CHF ₃ ) are used as the source gas holding units 801, 802, and 803, respectively. Since others are the same as those of the first embodiment, description thereof is omitted.
Even when CCl ₄ gas or SiCl ₄ gas, which is Cl ₂ gas and chlorine compound gas, is used, the same result as in Embodiment 1 is obtained by setting the Cl ₂ flow rate / chlorine compound gas flow rate ratio to 2-5. It is done.

(Embodiment 3)
Embodiment 3 will be described with reference to FIG.
In Embodiment 3, 2% methane (CH ₄ ) gas diluted with Cl ₂ gas, BCl ₃ gas, and He is used as the source gas holding units 901, 902, and 903, respectively. Since others are the same as those of the first embodiment, description thereof is omitted.
Even when CH ₄ gas, which is a gas containing hydrogen molecules, is added to Cl ₂ gas and chlorine compound gas, the same result as in Embodiment 1 can be obtained by setting the Cl ₂ flow rate / chlorine compound gas flow rate ratio to 2-5. can get.
In addition, it is desirable to add a gas containing hydrogen since an effect of compensating for hydrogen termination at the SiO ₂ —Si interface desorbed by ultraviolet rays from plasma irradiated on the solid-state imaging device can be expected.

(Embodiment 4)
The fourth embodiment will be described with reference to FIG.
In the fourth embodiment, 2% ethylene (C ₂ H ₄ ) gas diluted with Cl ₂ gas, BCl ₃ gas and He is used as the source gas holding parts 1001, 1002 and 1003, respectively. Since others are the same as those of the third embodiment, description thereof is omitted.
Even when C ₂ H ₄ gas, which is a gas containing hydrogen molecules, is added to Cl ₂ gas and chlorine compound gas, the ratio of Cl ₂ flow rate / chlorine compound gas flow rate is set to 2 to 5 as in the third embodiment. Results are obtained.

(Embodiment 5)
The fifth embodiment will be described with reference to FIG. FIG. 11 has a configuration in which the devices of FIG. 3 are stacked. The etching conditions are the same as those in the first embodiment.
FIG. 11 shows a semiconductor device in which a solid-state image sensor 1102 is formed on the surface of a semiconductor substrate 1101, and at least one insulating film 1104 and one or more metal films 1105 are formed on the solid-state image sensor 1102. ing. The etching angle 1106 of the insulating film 1104 below the metal film 1105 with respect to the surface of the semiconductor substrate 1101 is preferably 85 to 88 °.

A semiconductor substrate 1101 in FIG. 11 is a silicon wafer, and a semiconductor wafer having a diameter of 200 mm and a thickness of 0.625 mm is used here. The diameter and thickness are not limited, and a diameter of 300 mm or a thickness of 0.725 mm may be used. Reference numeral 1102 denotes a solid-state image sensor section formed on the silicon wafer surface. In this embodiment, a CMOS type solid-state image sensor is formed, but a CCD type or other solid-state image sensor may be used.
Reference numeral 1103 denotes a photosensitive portion of the solid-state image sensor unit 1102, which is a part that converts light from the surface into an electric signal. In this embodiment, a photodiode is formed.

Reference numeral 1104 denotes an insulating film, and 1105 denotes a metal film. The insulating film 1104 electrically insulates between the metal films 1105 and the metal film 1105 and the solid-state imaging element 1102. In this embodiment, the insulating film 1104 is made of silicon dioxide (SiO ₂ ) by a chemical vapor reaction deposition (PE-CVD) method using a plasma reaction. It is preferable that the insulating film can transmit light and can be electrically insulated. For example, in addition to the above, an SiO ₂ film to which F is added, an organic film mainly containing carbon, and the like can be given. The film forming method may be a high density plasma (HDP) method or a chemical vapor deposition method using a plasma reaction.

  The metal film 1105 only needs to be a wiring material having a function of transmitting a photoelectric conversion signal and a control signal of the solid-state image sensor 1102. In this embodiment, the metal film 1105 is a laminated film of titanium nitride (TiN) / aluminum (Al) / titanium nitride (TiN) / titanium (Ti). In this embodiment, a three-layer wiring structure is used. However, there is no problem even if the number of pixels of the solid-state image sensor 1102 is increased or decreased.

  Reference numeral 1106 denotes an etching angle of the insulating film 1104 below the metal film 1105 with respect to the surface of the semiconductor substrate 1101. This angle means an angle formed by the overetched portion formed when the metal film 1105 is etched.

  In Embodiment 5, the semiconductor substrate 1101 is cleaved to obtain a cross-sectional structure. Thereafter, the substrate is immersed in a 5% hydrofluoric acid solution for 10 seconds, and the cleavage plane is observed with a scanning electron microscope (SEM). The etching angle 1104 can be measured from the result of this observation.

  Reference numeral 1107 denotes a protective film. In the fifth embodiment, a silicon nitride (SiN) film formed by a PE-CVD method is used. A color filter 1108 has a function of selectively transmitting red, green, and blue light. Reference numeral 1109 denotes a flattening film, which has a function of flattening the steps of the color filter 1108. Reference numeral 1110 denotes an on-chip lens having a function of condensing external light onto the photosensitive portion 1103. The color filter 1108, the planarization film 1109, and the on-chip lens 1110 are made of, for example, an organic material.

FIG. 12 shows the relationship between the etching angle 1106 and the S / N ratio of the semiconductor device of this embodiment.
It can be seen that the correlation between the over-etched portion 1106 angle and the S / N ratio is high. For example, when the overetched portion 1106 is processed at less than 85 °, a deterioration phenomenon of the S / N ratio is observed. If it is set as 85-88 degrees, since deterioration of S / N ratio can be suppressed, it is preferable.

  The reason why the light can be suppressed is considered to be that the light condensing rate to the photosensitive portion 1103 is lowered by being refracted and reflected in the overetched portion before the light from the outside reaches the solid-state imaging device 1102. Therefore, a highly sensitive solid-state imaging device can be obtained by setting the angle of the overetched portion to 85 to 88 °.

1 is a configuration diagram of an etching apparatus according to Embodiment 1. FIG. 3 is a detailed cross-sectional view of the object to be processed according to Embodiment 1. FIG. FIG. 3 is a detailed cross-sectional view after the etching process of the target object according to the first embodiment. FIG. 4 is a relationship diagram between a Cl ₂ flow rate and a BCl ₃ flow rate and an etching angle according to the first embodiment. 4 is a relationship diagram between a Cl ₂ / BCl ₃ flow rate ratio and an etching angle according to Embodiment 1. FIG. FIG. ₃ is a relationship diagram between a Cl ₂ flow rate and a BCl ₃ flow rate and an S / N ratio according to the first embodiment. 4 is a relationship diagram between a Cl ₂ / BCl ₃ flow rate ratio and an S / N ratio according to Embodiment 1. FIG. FIG. 6 is a configuration diagram of an etching apparatus according to a second embodiment. FIG. 5 is a configuration diagram of an etching apparatus according to a third embodiment. It is a block diagram of the etching apparatus which concerns on Embodiment 4. FIG. FIG. 6 is a cross-sectional view of a semiconductor device according to a fifth embodiment. FIG. 10 is a relationship diagram between an etching angle and an S / N ratio according to the fifth embodiment.

Explanation of symbols

101 vacuum vessel, 102 electrode, 103 workpiece,
104, 105, 106 Gas flow rate control means,
107, 108, 109 valve,
110, 111, 112, 801, 802, 803, 901, 902, 903, 1001, 1002, 1003 Raw material gas holding unit,
113 vacuum evacuation means, 114 gas pressure control means,
115, 117 AC power supply, 116, 118 matcher,
119 loop antenna, 120 dielectric plate, 201 silicon wafer,
202, 1102 solid-state image sensor, 203, 1103 photosensitive portion,
204, 301, 1104 insulating film,
205, 206, 207, 302, 303, 304, 1105 metal film,
208 connections, 209 mask pattern,
305, 1106 etching angle, 1101, semiconductor substrate,
1107 Protective film, 1108 color filter, 1109 flattening film,
1110 On-chip lens

Claims (8)

Etching at least a metal film formed on the insulating film to obtain a metal wiring; and etching a part of the insulating film using the metal wiring as a mask;
Etching of a part of the insulating film is etching by plasma derived from a processing gas containing chlorine gas and chlorine compound gas under supply of high-frequency power and under vacuum,
The method of manufacturing a semiconductor device, wherein the chlorine gas and the chlorine compound gas are used at a ratio of a chlorine gas flow rate to a chlorine compound gas flow rate of 2 to 5 times. The method for manufacturing a semiconductor device according to claim 1, wherein the chlorine compound gas contains any one of BCl ₃ , SiCl ₄ , and CCl ₄ .   The insulating film in which the one part is etched includes an unetched surface under the metal wiring, an etched surface other than under the metal wiring, and a side surface that connects the unetched surface and the etched surface, The method of manufacturing a semiconductor device according to claim 1, wherein the etching surface has a taper angle of 85 to 88 °.   The etching of the metal film is etching by plasma derived from a processing gas containing chlorine gas, chlorine compound gas, and a gas containing at least one hydrogen atom under supply of high-frequency power and under vacuum. 4. A method for manufacturing a semiconductor device according to any one of 3 above. The method for manufacturing a semiconductor device according to claim 4, wherein the gas containing one or more hydrogen atoms includes any one of CHF ₃ , CH ₂ F ₂ , CH ₃ F, CH ₄ , and C ₂ H ₄ .   The method for manufacturing a semiconductor device according to claim 1, wherein the insulating film is a silicon oxide film, and the metal wiring is a film containing aluminum. A solid-state imaging device formed on a semiconductor substrate, an insulating film formed on the semiconductor substrate so as to cover the solid-state imaging device, and a metal wiring formed on the insulating film,
The insulating film includes an etched surface other than under the metal wiring and a side surface connecting the unetched surface and the etched surface, and the side surface has a taper angle of 85 to 88 ° with respect to the etched surface. A semiconductor device.   The semiconductor device according to claim 7, wherein the solid-state imaging element has an S / N ratio of 8.9 to 9.0 dB.