JPH0430178B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a lower electrode formed on a substrate, a photoconductive film made of an amorphous material mainly composed of silicon and containing hydrogen, and a transparent electrode formed on the lower electrode. The present invention relates to a method of manufacturing a light-receiving element by sequentially forming a desired pattern.

For example, non-transparent metal electrodes containing at least Cr are arranged one-dimensionally on an insulating substrate, and an amorphous crystal mainly composed of silicon and containing hydrogen is placed in one-to-one correspondence on the metal electrodes. from the substrate side to the n ⁺ type conductive layer, the i or n type conductive layer, and the p
Transparent electrodes are formed in one-to-one correspondence on the semiconductor layer and the photoconductor layer, which are formed in the order of the conductive layer (hereinafter referred to as an amorphous hydrogenated silicon photodiode) or vice versa. In a stacked one-dimensional optical sensor, when reading out one-dimensional image information using a matrix drive method, it is applied to the surface portion of a metal electrode pattern containing at least Cr for two-layer wiring formed in parallel on the substrate. It is useful.

[Prior art]

In the example of the one-dimensional optical sensor mentioned above, a plurality of solid-state elements having a photoelectric conversion function and a signal accumulation function are arranged in a one-dimensional manner, and each solid-state element corresponds to one pixel to form a one-dimensional optical signal reading element array. It is an element that converts one-dimensional image information into an electrical signal externally by sequentially scanning each solid-state element within this element array, and in particular, a transparent electrode is formed to cover a photoconductor layer. .

A one-dimensional optical sensor in which such a transparent electrode is formed to cover a photoconductor layer has the following structure. This technique will be briefly explained below using an example of a one-dimensional sensor whose cross-sectional view and plan view are shown in FIGS. 1a and 1b. As shown in FIG. 1, a non-transparent metal electrode 2 containing at least Cr (a light sensor section 21 and a two-layer wiring section 22) is disposed on an insulating substrate 1.
An amorphous hydrogenated silicon photodiode 3 and an amorphous hydrogenated silicon isolation diode 4 are further formed on the electrode 2. At this time, diodes 3 and 4 are connected from the metal 21 side.
N ⁺ type conductive layers 31 and 41, i or n type conductive layers 32 and 42, and p type conductive layers 33 and 43 are formed in this order. Photodiode 3 and isolation diode 4 are usually formed at the same time. Photodiode 3
is electrically connected to the transparent electrode 7 through a contact hole 62 drilled at a desired position in the insulating layer 5, and the transparent electrode 7 is connected to the second layer wiring part metal electrode 22 through the contact hole 62. contact hole 6
4, the metal wiring 81 is connected to the row driving IC. On the other hand, the separation diode 4 is connected to the photodiode 3 through a common sensor part metal electrode 21, and the other side is connected to the column drive IC from a metal wiring 82 via a contact hole 61. To explain the operating principle based on FIG. 1, the incident light 10
reaches the photodiode 3 through the transparent electrode 7. Here, the light is absorbed to produce electron-hole pairs, and these carriers are accumulated in the metal electrode 21 by the reverse bias voltage V _T applied to the photodiode. At this time, the separation diode is biased in the opposite direction and is in an OFF state with respect to the wiring 82.
The accumulated carriers forward bias the isolation diode 4 provided on the same metal electrode 21.
The carrier stored in the ON state is read out to the outside through the wiring 82. The above storage and readout operations are performed by selecting the wiring 82 using a column drive IC,
One-dimensional image information can be extracted to the outside by sequentially driving each photodiode using a matrix drive method that selects the wiring 81 using a row drive IC. The one-dimensional optical sensor with this structure divides all pixels into a plurality of consecutive groups and scans each group together, so the scanning circuit can be greatly simplified. Furthermore, since the photodiode 3 and the isolation diode 4 can be formed in the same process, the production process is simpler than that of an isolation diode array fabricated using a conventional Si-IC process.

However, it has been found that the above manufacturing process has the following problems. First, a non-transparent metal electrode 2 containing at least Cr is formed in a desired pattern on a substrate 1. The reason for using a metal electrode containing at least Cr is that it has good adhesion when a SiO ₂ -based glass substrate is used as the substrate 1, and it also has good adhesion when an amorphous silicon hydride layer is deposited thereon. Furthermore, a selective photoetching process can be used for the SiO ₂ glass used as the insulating layer of the substrate and the two-layer wiring diagram.
The metal electrode 2 consists of an optical sensor part metal electrode 21 and a two-layer wiring part metal electrode 22. Next, a diode layer of amorphous hydrogenated silicon is deposited on the substrate 1. At this time, metal electrodes 21 and 2
2 is uniformly coated with a layer of amorphous hydrogenated silicon. Next, photoresist patterns corresponding to the photodiodes and isolation diodes, respectively, are formed on the amorphous hydrogenated silicon using a conventional photoresist process. Using this photoresist pattern as a mask, the amorphous hydrogenated silicon in the areas not covered by the photoresist pattern is removed by plasma etching using carbon fluoride gas (here, CF ₄ gas). Sensor part metal electrode 2
A photodiode 3 and a separation diode 4 each made of amorphous hydrogenated silicon are formed on the photodiode 1 in a predetermined shape. On the other hand, the metal electrode 2 of the two-layer wiring part
Since the amorphous silicon hydride layer on the electrode 22 needs to be completely removed, the surface of the electrode 22 is exposed to the CF ₄ plasma for a while even after the amorphous silicon hydride is removed. As a result, an extremely thin and durable insulating film mainly composed of Cr fluoride is formed on the surface of the electrode 22. After removing the photoresist without removing this film, a SiO ₂ -based insulating layer for two-layer wiring is formed, contact holes 61, 62, 63, 64 are made at predetermined positions by photoetching, and ITO (Indium Tin) is formed. Oxide) When the transparent electrode pattern 7 and the Al wiring patterns 81 and 82 are formed, electrical continuity between the two-layer wiring part metal electrode 22 and the ITO transparent electrode 7 and the Al wiring pattern 81 becomes poor. An example of this conduction failure is shown in FIG. 2. Incidentally, the contact area is approximately 4 mm ² , which is two to three orders of magnitude larger than the contact area of the element shown in FIG. Figure 2 compares the voltage-current characteristics of a Cr/ITO contact when the Cr surface is not exposed to CF ₄ gas plasma (line a) and when it is exposed to CF ₄ gas plasma (curve b). It is. As _is clear from Figure 2, Cr/
The ITO contact has a so-called ohmic characteristic in which the current I flows in proportion to the voltage from a region where the voltage V _b is 0.01 (V) or less, and the contact is normal. However, when the Cr surface is exposed to CF ₄ gas plasma, the voltage V _b of the Cr/ITO contact is
Below 0.01 (V), almost no current I flows,
At 0.01 (V) or more, the current I suddenly begins to flow.
It exhibits so-called non-linear characteristics. For example, I=
Comparing the resistance value at 0.1mA (= constant), the resistance value is more than 40 times that of a normal contact (more than 100KΩ when converted to the area of the contact resistance of the element shown in Figure 1). This is thought to be due to the presence of an extremely thin insulating film on the Cr surface at the contact interface between Cr and ITO, which was generated when the Cr surface was exposed to CF ₄ gas plasma.
When this insulating film is formed, a high resistance is connected in series to the photodiode 3 and isolation diode 4 from an equivalent circuit perspective, making it impossible to detect the optical signal received by the photodiode at a high speed. .

In the one-dimensional optical sensor shown in FIG. 1, after the optical signal charge is accumulated in the photodiode 3 for a certain accumulation time (for example, 2 to 5 ms), the separation diode 4 is loaded within an extremely short period of time (for example, 500 ns to 5 μs). A method (referred to as an accumulation operation method) is adopted in which the data is biased in the forward direction, turned on, and read out through the wiring 82. Further, the storage and readout operations described above are sequentially driven for each photodiode using a matrix drive method in which the wiring 82 is selected using a column driving IC and the wiring 81 is selected using a row driving IC. Therefore, if a contact failure occurs due to the formation of the above-mentioned insulating film in the contact holes 63 and 64, 100K is applied in series to the above-mentioned readout circuit system.
Since a high resistance of Ω or more is connected, it becomes impossible to sufficiently read out the accumulated optical signal charge during an extremely short readout time (5 μs or less). Therefore, in order to realize a high-speed facsimile device, the presence of contact failure due to the above-mentioned insulating coating is an extremely serious problem.

The present invention is extremely effective in obtaining a one-dimensional optical sensor that eliminates the above-mentioned drawbacks.

[Purpose of the invention]

As stated above, an object of the present invention is to remove at least Cr when processing an amorphous hydrogenated silicon layer by a plasma etching method using a fluorocarbon-based gas.
An object of the present invention is to provide a method for removing an insulating film generated when the surface of a metal electrode pattern containing .

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention aims at etching the surface of a metal electrode pattern containing at least Cr in the plasma when processing an amorphous hydrogenated silicon layer by a plasma etching method using a fluorocarbon-based gas. The insulating film formed by the exposure to the gas is oxidized by exposing it to oxygen gas plasma, and then immersed in a hydrochloric acid-nitric acid-water based etching solution to remove the insulating film and improve the signal readout speed. The aim is to realize a one-dimensional optical sensor with improved According to the present invention, a high-speed facsimile device can be realized.

The content of the present invention will be explained in detail below.

First, a metal containing at least Cr is deposited on a SiO ₂ -based transparent glass substrate by sputtering, resistance heating vacuum evaporation, or electron beam evaporation. The sputtering method may use either high frequency discharge (13.56 MHz) of Ar gas or direct current discharge. The Ar discharge gas pressure is usually in the range of 3×10 ⁻³ to 3×10 ⁻² Torr.
In the vacuum evaporation method and the electron beam evaporation method, the vacuum level inside the bell gear is set to 5×10 ^-5 Torr or less.
The glass substrate temperature is 150 to 250 for all three deposition methods above.
in the range of ℃. The metal containing at least Cr is usually pure Cr, Cr-Ni metal, Cr-Fe metal, or a mixture thereof. It's okay to stay.

The thus deposited metal containing at least Cr is processed into a desired pattern by a photoetching method using an aqueous solution of ceric ammonium nitrate as an etching solution to form the lower electrode 2.

An amorphous photoconductive film mainly made of silicon containing hydrogen is formed on the substrate on which the desired wiring is formed by glow discharge CVD or reactive sputtering.

The glow discharge CVD (Chemical Vapor
There are two types of deposition methods: RF coil method and bipolar discharge method. Both are used as discharge gas.
Using a mixed gas of a silane gas such as SiH ₄ and a rare gas such as argon or hydrogen gas, glow discharge is performed to generate hydrogen-containing silicon on the one-dimensional optical sensor substrate through a separation reaction of the silane gas. This is a method of depositing a primarily amorphous photoconductive film, and is distinguished from the reactive sputtering method, which uses a reaction of adding hydrogen to silicon. In the rf coil method, the reaction chamber is placed inside the rf coil.
A high frequency of 13.56 MHz was applied to cause a glow discharge of the mixed gas of SiH ₄ and argon introduced into the reaction chamber, and a mixture of silicon containing hydrogen was placed on the one-dimensional optical sensor substrate placed inside the reaction chamber. This method deposits an amorphous photoconductive film. In addition, the bipolar discharge method uses a normal sputtering device and applies a high frequency of 13.556 MHz between opposing electrodes to cause a glow discharge of a mixed gas of SiH ₄ and argon or hydrogen introduced into the reaction chamber. This is a method of depositing an amorphous photoconductive film mainly composed of silicon containing hydrogen on the one-dimensional optical sensor substrate installed. The substrate temperature during film formation is 100 to 3000°C, the pressure of the discharge gas is higher than that of the reactive sputtering method, from 5 × 10 ^-2 Torr to 2 Torr, and the composition of SiH ₄ gas in the discharge gas is 5 to 2 Torr.
It is within the range of 400 mol%.

During the deposition of the photoconductive film, if a trace amount of phosphorus hydride, e.g. phosphine (PH ₃ ), is mixed as a doping gas into the above-mentioned mixed gas of SiH ₄ and argon or hydrogen in an amount of about 0.01 to 5%, an n ⁺ type conductive layer can be obtained. In addition, a trace amount of boron hydride such as diporan (B ₂ H ₆ ) is added as a doping gas to the above-mentioned mixed gas of SiH ₄ and argon or hydrogen.
A p-type conductive layer can be obtained by mixing about 0.01 to 5%. If these doping gases are not added, an n- or i-type conductive layer is generally obtained.
Using the above glow discharge CVD conditions, a photoconductive film is deposited in the order of an n ⁺ type conductive layer, an i or n type conductive layer, and a p type conductive layer to form a conductive film for a photodiode and a separation diode.

Further, as the reactive sputtering method for the photoconductive film, a general sputtering device or a magnetron type high-speed sputtering device can also be used. Polycrystalline silicon is installed as a sputtering target on one cathode (target side electrode) of the opposing electrodes in the sputtering device, and a one-dimensional photosensor substrate with desired wiring is placed on the other anode (substrate side electrode). Install. Spatsuta room 1x
250 to 300℃ while maintaining high vacuum below 10 ^-6 Torr
After heating to and degassing the spatsuta chamber,
A mixture of hydrogen, a rare gas such as argon, and a small amount of doping gas is introduced into the sputtering chamber as a discharge gas, and high-frequency sputtering is performed at 13.56 MHz. A crystalline photoconductive film is deposited. The substrate temperature during film formation is 100 to 300° C., the pressure of the discharge gas is 8×10 ⁻⁴ Torr to 2×10 ⁻² Torr, and the composition of hydrogen gas in the discharge gas is within the range of 10 to 60 mol %. During deposition of the photoconductive film, a trace amount of nitrogen gas (approximately 0.01% to 1%) is mixed as a doping gas into the above-mentioned mixed gas of argon and hydrogen, or a trace amount of phosphorus hydride such as phosphine (PH ₃ ) is mixed.
An n ⁺ type conductive layer can be obtained by mixing about 0.01 to 5%, and a trace amount of boron hydride such as diborane (B ₂ H ₆ ) is added to the above mixed gas of argon and hydrogen at about 0.01 to 5%.
A p-type conductive layer can be obtained by mixing about 55%. If these doping gases are not added, an i- or n-type conductive layer is generally obtained. Using the above sputtering conditions, a photoconductive film is deposited in this order: an n ⁺ type conductive layer, an i or n type conductive layer, and a p type conductive layer, to form a conductive film for a photodiode and a separation diode.

After forming a conductive film made of amorphous hydrogenated silicon on a one-dimensional sensor substrate by the above method, the conductive film is processed into a desired pattern by plasma etching using a fluorocarbon gas. and an element array of isolation diodes is completed. Processing an amorphous silicon hydride film using a plasma etching method using a carbon fluoride gas has the advantage that there is less deterioration in processing accuracy due to resist peeling than with a wet etching method, and there is also a reduction in processing accuracy during the photoetching process. Maximum heat treatment temperature
It has the advantage of being able to be carried out at temperatures below 200°C and not causing any deterioration of the film quality of the amorphous hydrogenated silicon film.
This is a generally widely used method. _CF4 gas is usually used as the carbon fluoride gas, but
_C2F6 , _C3F8 , _CClF3 , _C2ClF5 , _{CBrF3 gases} can also _be used _. When performing plasma etching of the amorphous hydrogenated silicon film using the above gas, it is necessary to perform the plasma etching with a slight overetch in order to completely remove the portions other than the photodiode 3 and isolation diode 4 patterns to be left. At this time, the lower electrode wiring patterns 21 and 22 containing at least Cr are exposed to the plasma of the above gas, and an insulating film is formed on the surface.
This insulating film poses no particular problem in terms of electrical properties on the lower electrode wiring pattern 21 for photo and isolation diodes, but on the lower electrode pattern 22 for two-layer wiring, as described above, Cr/
ITO contact 63 and Cr/Al contact 6
4, a contact failure occurs, which poses a problem in terms of electrical characteristics. The presence of such an insulating film not only indicates poor electrical connections, but also causes problems such as AES analysis (Ausier electron spectroscopy) and IMA analysis (Ion Micro Analizer).
This can be confirmed by As a result of the above analysis, it was found that the insulating film was mainly composed of Cr fluoride. In addition, the presence of some carbon as an impurity has also been confirmed. The thickness of this insulating film is extremely thin, about 5 to 100 Å, and normally it does not completely block the current, but is observed as a conduction failure as shown by curve b in FIG. 2. Therefore, it is necessary to remove the insulating film in a step after the plasma etching step of the amorphous hydrogenated silicon film and before depositing the ITO transparent electrode film.

As a result of examining various methods for removing the above-mentioned insulating film, it was found that the removal method described below is effective. Figure 3 shows an example of the process of removing the insulating film.
FIG. 3 is a diagram showing voltage-current characteristics of a Cr/ITO contact. Straight line a in Figure 3 is straight line a in Figure 2.
This is the same as normal contact characteristics. Similarly to curve b in FIG. 2, curve b in FIG. 3 shows the characteristics of a contact whose Cr surface has deteriorated due to exposure to CF ₄ gas plasma. When the Cr surface is exposed to CF ₄ gas plasma and then immersed in a hydrochloric acid-nitric acid-water etching solution, the contact characteristics are improved and become the characteristics shown in curve c. However, this characteristic cannot be said to be a sufficiently good contact characteristic compared to the straight line a, which is a normal contact characteristic. On the other hand, the Cr surface
Exposure to O ₂ gas plasma instead of CF ₄ gas also causes contact failure as shown in curve d, but this can be changed to straight line e by adding a step of immersion in a hydrochloric acid-nitric acid-water based etching solution. Significant improvements were observed as shown. From this
It can be seen that the insulating film mainly composed of chromium oxide, which is produced by exposing the Cr surface to O ₂ plasma, can be easily removed using a hydrochloric acid-nitric acid-water based etching solution. Therefore, after exposing the Cr surface to CF ₄ gas plasma, it is further exposed to O ₂ gas plasma to replace some of the fluorine in the insulating film, which is mainly composed of chromium fluoride, with oxygen. I tried to remove it by immersing it in a nitric acid-water based etching solution.
As a result, the contact characteristics deteriorate further as shown in curve f by adding O ₂ gas plasma treatment from CF ₄ gas plasma, but by immersion in a hydrochloric acid-nitric acid-water based etching solution,
It has been found that the contact characteristics are greatly improved as shown by the straight line g. The contact characteristics shown by the straight line g are equivalent to the normal contact characteristics shown by the straight line a.

Here, a plasma etching method for an amorphous hydrogenated silicon film will be specifically described. First, place an electrode on the outside of a quartz vacuum chamber, and
By applying a high frequency of 13.56MHz, a discharge is caused in the vacuum chamber. At this time, CF ₄ gas at a pressure of 0.1 to 5 Torr is pumped into the vacuum chamber and exhausted by a rotary pump. The aforementioned one-dimensional photosensor substrate on which a desired photoresist pattern has been formed is placed in this discharge gas plasma and etched. The discharge power is 50 to 200 W, and the etching time is 1 to 5 minutes. In this process, Cr
An insulating film is formed on the surface.

Next, the method of O ₂ plasma treatment will be specifically described. This process uses the same equipment and method as the CF ₄ gas plasma etching method described above. However, at this time, instead of _CF4 gas in the vacuum chamber, 0.5
~7Torr of _O2 gas is pumped in and exhausted by a rotary pump. The substrate that has been subjected to the CF ₄ gas plasma treatment is placed in this O ₂ gas plasma and subjected to plasma treatment. Discharge power is 100~
300W, processing time is 1-5 minutes.

Next, hydrochloric acid-nitric acid-water etching treatment will be specifically described. Commercially available concentrated hydrochloric acid and concentrated nitric acid are used as hydrochloric acid and nitric acid. For example, use hydrochloric acid with a hydrogen chloride content of 36wt% and a specific gravity of 1.18.
Nitric acid with a HNO ₃ content of 65 wt% and a specific gravity of 1.40 is used. The composition of the etching solution is vol% of the above acid.
Expressed as: Hydrochloric acid - nitric acid - within the composition range of concentrated hydrochloric acid composition 20 to 80 vol% and concentrated nitric acid composition 1 to 20 vol%.
It was found that an aqueous etching solution was suitable. Further, it has been found that the temperature of the above-mentioned etching solution is suitably in the range of 35 to 55°C.

The fact that this etching solution exhibits a more effective etching effect on the insulating film mainly composed of Cr oxide than on the above-mentioned insulating film mainly composed of Cr fluoride is shown by the straight line in Figure 3. It is clear from the comparison between c and straight line e. Therefore, the above
It is desirable that the insulating film mainly composed of Cr fluoride is partially replaced by an insulating film mainly composed of Cr oxide by O ₂ plasma treatment, and then subjected to the above etching solution treatment. It is thought that the effect of this etching solution can basically be explained by the well-known reaction mechanism of aqua regia. That is, HNO ₃ +3HGCl→2(Cl)↑+NOCl+2H ₂ O
...(1) Here, (Cl) is nascent chlorine NOCl is called nitrosyl chloride.

(Cl) is highly reactive, so the Cr surface
It acts on Cr fluoride or Cr oxide and elutes as water-soluble Cr chloride.
It is thought that the insulating film can be removed. In particular, the fact that it acts more effectively on Cr oxides than on Cr fluorides also supports the involvement of this mechanism. That is, the insulating film mainly composed of Cr fluoride described here is chemically stable and cannot be easily removed by using water, hot hydrochloric acid, nitric acid, sulfuric acid, or the like alone. This is a chemically stable divalent or trivalent
This is thought to be because Cr fluoride is the main component. Therefore, once the fluoride of Cr is changed to an oxide,
Furthermore, it is effective to remove it in the form of chloride.

The hydrochloric acid-nitric acid-water based etching solution of the present invention is (1)
As the reaction shown in the formula progresses, it gradually loses its effectiveness, so a solution that has been prepared for about 3 to 5 days will become less effective and will need to be remade. However, in the normally used one-dimensional optical sensor manufacturing process, the immersion time is 5 to 15 minutes, so if it is prepared each time it is used, there will be no practical problem.

Further, the method for removing an insulating film of the present invention is applicable not only to the one-dimensional optical sensor using amorphous hydrogenated silicon shown as an example in FIG.
It goes without saying that the present invention can also be applied to other thin film device manufacturing processes that include plasma etching of a two-layer wiring insulating film such as a SiO ₂ or Si ₃ N ₄ film using a fluorocarbon gas.

[Embodiments of the invention]

The present invention will be explained in detail below with reference to Examples.

Example 1 FIGS. 4 to 11 are cross-sectional views of a pixel portion showing a method of manufacturing a one-dimensional optical sensor of the present invention. Metallic chromium is deposited on an insulating glass substrate 1 to a thickness of about 2000 Å by sputtering, and then a desired electrode pattern 2 is formed by a photoetching process using a ceric ammonium nitrate based etching solution (Fig. 4). ). Here, 21 is an electrode for a photodiode and a separation diode, and 22 is a lower electrode for a two-layer wiring. Next, this substrate was placed in a two-electrode glow discharge CVD device, and _H2 gas containing 10% _SiH4 gas was introduced into the reaction chamber as a discharge gas.
1 Torr, PH ₃ gas as a doping gas at a volume ratio (PH ₃ /SiH ₄ ) of 1%, and a high frequency discharge of 13.56 MHz is performed to mainly form amorphous silicon hydride. An n ⁺ type conductive layer is deposited on the substrate to a thickness of 250 Å. Furthermore, the supply of _PH3 gas into the reaction chamber was stopped for 10
High frequency discharge is continued using only a mixed gas of %SiH ₄ +90%H ₂ to deposit an i-type conductive layer mainly composed of amorphous hydrogenated silicon to a thickness of 5500 Å. moreover,
In addition to the above discharge gas, as a doping gas
B ₂ H ₆ gas was introduced at a volume ratio of 1% (B ₂ H ₆ /SiH ₄ ) and high frequency discharge was continued to form a p-type conductive layer mainly made of amorphous silicon with a thickness of 400 Å. Let it accumulate on the surface. When the amorphous hydrogenated silicon film having the n ⁺ -i-p structure thus formed is patterned into a predetermined shape by plasma etching using CF ₄ gas, a photodiode 3 and a separation diode 4 are formed (Fig. 5). ). Here, 31 is an n ⁺ type conductive layer, 32 and 42 are i type conductive layers, 33 and 43 are p type conductive layers, 10 is photoresist, and 11 is CF ₄ plasma. In FIG. 5, the portions not covered with the photoresist 10 are exposed to CF ₄ plasma, and an insulating film mainly composed of Cr fluoride is formed on the surfaces of the metal chromium patterns 21 and 22. In FIG.
The plasma etching conditions at this time are CF ₄ gas pressure.
Etching is performed for 3 minutes at 0.5 Torr, 13.56 MHz high frequency power of 100 W. Next, O ₂ gas was introduced instead of CF ₄ gas, and the O ₂ gas pressure was 2 Torr.
Perform O ₂ gas plasma treatment for 2 minutes at 13.56MHz high frequency power of 200W (Figure 6). Here, 12 is O ₂
It is gas plasma. Through this treatment, a part of the insulating film mainly composed of Cr fluoride is oxidized and transformed into an insulating film soluble in the etching solution described below. This substrate was then heated with HCl: _HNO3 :
Etching solution 1 of H ₂ O = 1:0.08:1 (volume ratio)
3 to remove the insulating film (Fig. 7).
The temperature of the etching solution was 45℃, and the etching time was 5
It's a minute. After the above treatment, the photoresist 10 is removed by a conventional method to obtain a substrate with a clean chromium metal surface as shown in FIG.

Next, SiO ₂ glass was deposited on the above substrate to a thickness of 2 μm by sputtering method, and HF
-HNO ₃ -H ₂ O-based etching solution is used to photo-etch the contact holes 6 at predetermined locations.
When holes 1, 62, 63, and 64 are opened, an insulating film 5 for two-layer wiring is formed (FIG. 9). Then on top of this In ₂ O ₃
−SnO ₂ -based transparent electrode with sputtering method
The film is deposited to a thickness of 1.5 Å. At this time, an In ₂ O ₃ sintered body containing 5 mol % of SnO ₂ is used as a sputtering target by placing it on the cathode. High-frequency sputtering was performed at 13.56MHz at a gas pressure of 1×10 ^-2 Torr using Ar gas as the discharge gas.
After forming the transparent electrode, temperature was increased to 225℃ to improve photoresponse characteristics.
Heat treatment is performed for 60 minutes, and the transparent electrode is patterned into a predetermined shape 7 by photoetching using an etching solution of HCl--HNO ₃ --H ₂ O-based, to obtain an element having a cross-sectional structure as shown in FIG. Next, this patterned ITO film is completely covered with a protective film made of photoresist, and then an Al film is deposited to a thickness of 2 μm on the substrate by vacuum evaporation.
In addition, a photoetching method using an H ₃ PO ₄ −HNO ₃ −H ₂ O-based etching solution was used to form double-layer interconnects.
Al electrode patterns 81 and 82 are formed. At this time,
The ITO film is coated with photoresist, and electrochemical reactions occur when it comes into contact with the Al etching solution.
Prevents elution of ITO membrane. After forming the Al electrode pattern, if the ITO protective film is removed by oxygen plasma ashing, a one-dimensional optical sensor with a high reading speed and no electrical continuity defects at the contact holes 63 and 64 as shown in FIG. 11 can be obtained. . Using this one-dimensional optical sensor, high-speed facsimile can be realized.

〔Effect of the invention〕

By applying the present invention, wiring with low contact resistance can be formed. FIG. 3 shows a comparison of characteristics in various methods.

[Brief explanation of drawings]

Figure 1 is a sectional view a and a plan view b showing the basic structure of the one-dimensional optical sensor of the present invention, and Figure 2 is
Figure 3 is a diagram comparing the normal contact characteristics (a) with the contact characteristics (b) in which amorphous silicon has poor conductivity due to the plasma etching process using CF ₄ gas in terms of Cr/ITO contact characteristics. 1 is a diagram showing the improvement progress of the contact failure improvement method of the present invention, and FIGS. 4 to 11 are sectional views of main parts showing the manufacturing process of the one-dimensional optical sensor of the present invention, respectively. 1...Substrate, 2...Non-transparent metal electrode, 21...
... Metal electrode for photodiode and separation diode, 22 ... Metal electrode for double-layer wiring, 3 ... Photodiode mainly made of amorphous hydrogenated silicon, 4
...Separation diode mainly made of amorphous hydrogenated silicon, 31, 41...n ⁺ type conductive layer mainly made of amorphous hydrogenated silicon, 32, 42... Mainly made of amorphous hydrogenated silicon n-type or i-type conductive layer, 33, 43...p-type conductive layer mainly composed of amorphous hydrogenated silicon, 5... insulating layer, 61, 6
2, 63, 64... Contact hole, 7, 14...
Transparent electrode or translucent metal electrode, 81, 82...
...Metal wiring, 10...Photoresist, 11...
CF ₄ gas plasma, 12... O ₂ gas plasma, 13... HCl-HNO ₃ -H ₂ O-based etching liquid.

Claims (1)

[Claims] 1. A process of forming a metal electrode pattern containing at least Cr on a desired substrate, and forming a material on the metal electrode that can be etched by a plasma etching method using a gas containing at least fluorine. A thin film comprising at least the steps of depositing a film, processing the etchable material film into a desired pattern by plasma etching using a gas containing at least fluorine, and forming an upper wiring pattern. In the manufacturing process of the device, an insulating layer is formed when the plasma of the fluorine-containing gas acts on the surface of the first layer metal electrode containing at least Cr, which was exposed in the plasma etching process of the fluorine-containing gas. A method for manufacturing a thin film element, comprising a step of removing a film. 2. The method of manufacturing a thin film element according to claim 1, wherein the fluorine-containing gas is a fluorocarbon-based gas. 3. The method of manufacturing a thin film element according to claim 1 or 2, wherein the etching material is made of an amorphous material mainly composed of silicon. 4. The method for manufacturing a thin film device according to any one of claims 1 to 3, wherein the etching material is a photoelectric conversion film containing hydrogen. 5. Manufacture of a thin film element according to any one of claims 1 to 4, characterized in that the etchable substance is a two-layer wiring insulating film containing at least SiO ₂ or Si ₃ N ₄ Method. 6 The manufacturing process of the above thin film element contains at least Cr.
A step of forming a metal electrode containing a metal electrode into a predetermined pattern consisting of an optical sensor part and a two-layer wiring part, and uniformly forming a photoelectric conversion film made of an amorphous material mainly composed of silicon and containing hydrogen on the metal electrode. After depositing, there is a step of forming a photoelectric conversion film in a predetermined pattern on the optical sensor portion of the metal electrode by plasma etching using a gas containing fluorine, and after forming an insulating film for two-layer wiring, the metal electrode is deposited. and a light-receiving element manufacturing process comprising the steps of forming a contact hole in a predetermined shape on the photoelectric conversion film, forming an indium oxide-tin oxide transparent electrode in a predetermined pattern, and forming an upper wiring pattern. A thin film device manufacturing method according to any one of claims 1 to 5, characterized in that: 7 The process of removing the above insulating film is performed using hydrochloric acid.
7. The method of manufacturing a thin film element according to claim 1, wherein the step is immersion in a nitric acid-water based etching solution. 8. Claims 1 to 6, characterized in that the step of removing the insulating film is a step of exposing the film to oxygen plasma and then immersing it in a hydrochloric acid-nitric acid-water based etching solution. The method for manufacturing a thin film element according to any one of the above. 9 The step of removing the insulating film described above is carried out using concentrated hydrochloric acid with a HCl content of 36 wt% and a composition of 20 to 80 vol%, and concentrated nitric acid with a _HNO3 content of 64 wt% and a composition within the composition range of 1 to 20 vol%. 9. The thin film device manufacturing method according to claim 1, wherein the step is immersion in an aqueous etching solution. The process of removing the above insulating film is at 35-55℃.
10. The method of manufacturing a thin film element according to claim 1, wherein the step is immersion in a hydrochloric acid-nitric acid-water etching solution having a temperature range of .