JP2838907B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device including a thin film transistor and an optical sensor and used as an image reading device or the like, and particularly to a long device having stable performance. The present invention relates to a method for manufacturing a semiconductor device suitable for obtaining an optical sensor array.

[Conventional technology]

2. Description of the Related Art In recent years, image reading apparatuses have been regarded as important as man-machine interfaces for OA equipment such as computers and facsimiles. From such a viewpoint, an image reading device using a long optical sensor array in which a thin film transistor and an optical sensor are formed on a large-area insulating substrate using a thin-film semiconductor, for example, hydrogenated amorphous silicon, polysilicon, or the like, has been proposed. Developed CCD
This eliminates the need for a lens of a reduction optical system, which was required for the image reading device, and contributed to miniaturization. Further, the same thin film semiconductor can be used to form a thin film transistor for driving an optical sensor on the same substrate, and miniaturization and cost reduction are being promoted. In addition, by using a thin film transistor type optical sensor having a gate electrode and a gate insulating film, the optical sensor and the thin film transistor can be obtained in the same process, and a stable photocurrent can be obtained. I know.

FIG. 7 shows an example of the structure of a conventional thin film transistor (hereinafter referred to as "TFT"). A gate insulating film 3 is deposited on the gate electrode 2 and further a thin film semiconductor 4 serving as a channel;
For example, hydrogenated amorphous silicon (hereinafter a-Si: H)
And so on. Further, an n ⁺ layer 5 is provided between the metal electrodes of the source and drain upper electrodes 6 and 7, and by forming a junction having ohmic properties against electrons and blocking properties against holes, n ⁺ It operates as a channel transistor. The TFT of FIG. 7 can also be used as an optical sensor using the gate electrode 2 as an auxiliary electrode. When light enters between the source and drain metal electrodes, it is obtained as a secondary photocurrent. The carrier in the thin film semiconductor 4 is controlled by the gate electrode 2, and a stable photocurrent can be obtained.

FIG. 8 shows a conventional method of manufacturing the thin film transistor and the thin film transistor type optical sensor shown in FIG. 7 (for example, Japanese Patent Application Laid-Open No. 63-9157). In FIG. 8 (a), 1 is a glass substrate, and 2 is a Cr layer serving as a gate electrode. After the gate electrode 2 is selectively formed, for example, the silicon nitride film 3 serving as a gate insulating film is formed at 3000 ° by plasma CVD, the a-Si: H ₄ layer 4 serving as a semiconductor layer is formed at 5000 °, and n of the ohmic contact layer is formed.
⁺ Layer 5 is deposited continuously with a thickness of 1500 °. Further, an aluminum layer 6a to be the source and drain upper electrodes 6, 7 is deposited by a sputtering method or the like. After that, the photosensitive resin 8 is applied to the entire surface, and then exposed and patterned. FIG. 8 (b)
Shows a state after patterning of the aluminum layer which is the source and drain upper electrodes 6 and 7. At this time, there is a photosensitive resin layer 8 on the electrode. Using the photosensitive resin layer 8 as a mask, the n ⁺ layer 5 is etched to a predetermined depth by RIE or the like (FIG. 8C), and then the photosensitive resin layer 8 is peeled off (FIG. 8 ( d)). Further, after patterning the photosensitive resin layer 8 again and performing element isolation by RIE or the like (FIG. 8 (e)), the surface of the element is silicon nitride (Si ₃ N ₄ ) or silicon oxide (SiO _2). 8) (FIG. 8 (f)) to form the thin film transistor and the thin film transistor type optical sensor of FIG.

(Problem to be Solved by the Invention) A thin film transistor and a thin film transistor type optical sensor manufactured by the conventional method are formed on a glass substrate or the like, and when used as a long optical sensor such as an image reading device, the ninth aspect. The optical sensor substrate sliced as shown in the figure is attached to the unit housing. At this time, cracking of the protective film and peeling of the film occur at the slice end face. As the length of the protective film further increases, the film is expected to peel off due to the internal stress of the protective film. The protective film protects thin film transistors and optical sensors,
Since the matrix wiring of signal lines and the like must be protected from metal corrosion, they are formed on almost the entire surface of the optical sensor substrate. Therefore, improving the adhesion between the protective film and the substrate is a major issue for increasing the yield as an optical sensor substrate.

The present invention has been made to solve the above-described problems associated with such a conventional semiconductor device manufacturing method,
It is an object of the present invention to provide a method for manufacturing a semiconductor device in which the adhesion of a protective film to a substrate is remarkably improved and the performance is not deteriorated due to peeling of the protective film.

[Means to solve the problem (and action)]

The method of the present invention comprises the steps of laminating and providing a plurality of layers for forming a plurality of semiconductor elements having electrodes on an insulating substrate, and forming a plurality of layers between the elements to separate each semiconductor element from each other. A method of manufacturing a semiconductor device, comprising: a removing step of removing a part of a layer; and a step of providing an insulating protective layer covering the element region on the insulating substrate. The surface of the insulating substrate is roughened by reactive ion etching or wet etching using a solution containing HF to a sufficient degree to increase the adhesion between the insulating substrate and the insulating protective layer. An insulating protective layer is provided in contact with the planarized surface. The substrate that has undergone this surface roughening step has excellent adhesion to the protective layer formed in the subsequent step, whereby it is possible to obtain an excellent semiconductor device without deterioration in performance due to peeling of the protective film. it can.

The surface roughening step can be performed by using an etching method generally applied to semiconductor processing, and the most preferable means is dry etching, particularly reactive ion etching (RIE). However, it is also possible to apply wet etching performed using a solution of a substance containing H or F atoms.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 (a) to 1 (g) show steps of manufacturing a thin film transistor and a thin film transistor type optical sensor according to the present invention.

FIG. 1A shows that a gate electrode 32 made of Cr is selectively formed in a predetermined region on an insulating substrate 31, and then a gate insulating film 33 is formed.
Hydrogenated amorphous silicone nitride film (hereinafter referred to as “a
−SiNx: H) is 3000 mm, and hydrogenated amorphous silicon (hereinafter referred to as “a-Si: H”) to be the thin film semiconductor 34 is
5000Å, n ⁺ layer 35 with 1500Å thickness, each plasma CV
This shows a state where they are sequentially deposited by the D method.

FIG. 1 (b) shows the source and drain upper electrodes 36, 3 later.
This shows a state in which a photosensitive resist film 38 for patterning the upper electrodes of the source and drain is applied after depositing Al to be 7 by a 1 μm sputtering method.

FIG. 1 (c) shows a state in which after the photosensitive resist is patterned into a desired pattern, Al of the source and drain upper electrodes is formed by wet etching using the photosensitive resist film 38 as a mask.

FIG. 1D shows a state in which the n ⁺ layer 35 is etched to an etching depth by RIE using the source and drain electrodes as a mask.

FIG. 1 (e) shows a state in which element separation has been performed by RIE after patterning into a desired pattern with a photosensitive resist film.

Further, in FIG. 1 (f), RIE using CF ₄ gas, H ₂ gas or the like is continuously performed on the surface of the insulating substrate 31 whose surface is exposed by the element separation, and the exposed surface of the insulating substrate 31 is removed. This shows a state of vandalism.

FIG. 1 (g) shows a state in which a protective layer 0 of a silicon nitride film is formed on the surface of the thin film semiconductor formed in FIG. 1 (d) by a plasma CVD method.

Also, instead of the RIE step of FIG. 1 (f), a solution containing HF, for example, an etching solution consisting of HF: HNO ₃ : CH ₃ COOH = 1: 1: 80 is used, and the substrate is contained in this solution. At room temperature 30
It is also possible to apply a wet etching step performed by dipping for 2 seconds.

FIG. 2 shows a cross-sectional view of the optical sensor array obtained in this manner.

In the above embodiment, the case where hydrogenated amorphous silicon is used has been described.
For example, similar effects could be obtained when applied to polysilicon, CdS, and the like.

FIG. 3 is a sectional view showing a case where the optical sensor obtained according to the method of the present invention is applied to an image reading apparatus such as a facsimile. The incident light from the light source 45 is reflected by the original 43,
Photoelectric conversion is performed by the optical sensor created in the step of FIG.

FIG. 4 shows an example of a circuit of a thin-film transistor type optical sensor and a complete contact type sensor constituted by a thin-film transistor according to the present invention.

In the figure, reference numeral 20 denotes a wiring portion formed in a matrix,
21 is an optical sensor unit using the thin film transistor type optical sensor according to the present invention, 22 is a charge accumulating unit, 23a is a transfer switch using the thin film transistor according to the present invention, and 24b is a thin film transistor according to the present invention for resetting the electric charge of the charge accumulating unit 22 , And 25 is a lead connecting the signal output of the transfer switch to the signal processing IC. In this embodiment, a-Si: H is used as a photoconductive semiconductor layer constituting the light sensor unit 21, the transfer switch 23a, and the discharge switch 23b.
A film is used, and a silicon nitride film formed by plasma CVD is used as an insulating layer.

In FIG. 4, for simplicity, only upper and lower electrode wirings are shown, and the photoconductive semiconductor layer and the insulating layer are not shown. Further, an n ⁺ layer is formed at the interface between the upper electrode wiring and the semiconductor layer, and an ohmic junction is established.

FIG. 5 shows an equivalent circuit of a thin-film transistor type photosensor of the present invention and a circuit of a complete contact type sensor constituted by a thin-film transistor. In the figure, S _i.1 , S _i.2 ,
S _i.3 ,... S _iN are optical sensors constituting the optical sensor section 21 in FIG. 4, where i is the block number and 1 to N are the number of bits in the block. (Hereinafter referred to as S _{i, N.} ) In the same figure, C _iN is a capacitor of the charge storage unit 22,
The respective photocurrents are accumulated corresponding to the photosensors _SiN . Further, correspond similarly transistor ST _iN the transfer switch 23a for transferring the charge in the storage capacitor C _iN to the load capacitor CX _N, also transistor SR _iN the discharge switch 23b for resetting the charge.

The photosensor S _iN , the storage capacitor C _iN , the transfer switch transistor ST _iN , and the discharge switch transistor SR _iN are arranged in an array in a row, and N blocks constitute one block. Is divided into blocks. For example, if the number of sensors is 1728, N = 32 and M = 54. Transfer switches ST _iN provided in an array,
The gate electrode of the discharge switch SR _iN is connected to the gate wiring section. The gate electrode of the transfer switch ST _iN is commonly connected in the first block, and the discharge switch SR _iN
The gate electrode of _iN is connected to the gate electrode of the transfer switch of the block of the next order.

The common lines (gate drive lines G ₁ , G ₂ , G
_3, ... G _M) is driven by the gate driver 246. On the other hand, the signal output is a lead line in a matrix configuration.
230 (signal output lines D ₁ , D ₂ , D ₃ ,..., D _N )
7 (in blocks) connected. In addition, the optical sensor S _iN
Are connected to the drive unit 250, and a negative bias is applied.

In such a configuration, the gate drive lines G ₁ , G ₂ , G ₃ ,.
_{In M} , selection pulses (VG ₁ , VG ₂ , VG
₃ , ... VG _M ) are supplied. First, when G ₁ is selected gate driving line, transfer switches ST _1.1 ~ST _1.N is turned ON, the charges accumulated in the storage capacitor C _1.1 -C _1.N load capacitor CX ₁ ~CX _N Is forwarded to Next, when the gate driving line G ₂ is selected, the transfer switch ST _2.1 ~ST _2.N is ON
_Then , the charge stored in the storage capacitors C _{2.1 to} C _2.N is transferred to the load capacitors CX _{1 to} CX _N , and at the same time, the storage capacitors C _1.1 to C _1.N are discharged from the discharge switches SR _{1.1 to} SR 1.N.
_{1. The N} charge is reset. In the same manner, the gate driving line _{G 3, G 4, G 5} , ... is also selected for G _M, the read operation is performed. These operations are performed for each block, the signal output VX ₁ of the _{blocks, VX 2, VX 3, ...} VX N input D _1, D _2, D ₃ of the signal processing unit 247, is sent to the ... D _N , And is output after being converted into a serial signal.

Further, in this embodiment, as shown in FIG. 6, a wear-resistant layer 42 is formed on the upper part of the optical sensor so that the light source 45
Described a lensless complete contact sensor array that reads an original 43 by illuminating it, but also uses a close-up imaging lens (for example, a product name “Selfoc lens” manufactured by Nippon Sheet Glass Co., Ltd.) It can also be used for a type image reading device.

FIG. 6 is a schematic configuration diagram illustrating an example of a facsimile having a communication function as an image information processing device configured using the optical sensor obtained in the present embodiment.

Here, reference numeral 102 denotes a feeding roller as feeding means for feeding the document 101 toward the reading position, 103 denotes a light source, and 104 denotes a document.
This is a separation piece for reliably separating and feeding 101 sheets one by one. Reference numeral 106 denotes a platen roller which is provided at a reading position with respect to the optical sensor 100, regulates the surface to be read of the original 101, and transports the original 101.

P is a recording medium in the form of a roll paper in the illustrated example, and image information read by the optical sensor 100 or, in the case of a facsimile apparatus or the like, image information transmitted from the outside is reproduced here. Reference numeral 110 denotes a recording head as recording means for performing the image formation, and various types such as a thermal head and an ink jet recording head can be used. The recording head may be of a serial type or a line type. Reference numeral 112 denotes a platen roller as a transport unit that transports the recording medium P to a recording position of the recording head 110 and regulates a recording surface thereof.

Reference numeral 120 denotes an operation panel provided with switches and messages for accepting operation inputs as input / output means, a display unit for notifying the status of the apparatus, and the like. 13
Reference numeral 0 denotes a system control board as control means, and a control unit (controller) for controlling each unit,
A drive circuit (driver) for the photoelectric conversion element, a processing unit (processor) for image information, a transmission / reception unit, and the like are provided. 104
Is the power supply of the device.

Recording means used in the information processing apparatus of the present invention include, for example, U.S. Pat. Nos. 4,723,129 and 4,740,7
It is preferable that the typical structure and principle are disclosed in the specification of No. 96. According to this method, at least one of the electrothermal transducers arranged corresponding to a sheet or a liquid passage holding a liquid (ink) is provided with a rapid temperature rise exceeding film boiling corresponding to recorded information. By applying a drive signal, heat energy is generated in the electrothermal transducer, causing the film to boil on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) corresponding to the drive signal one-to-one. Is effective because By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble,
Form at least one drop.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be reduced by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration that satisfies the condition or a configuration as a single recording head that is integrally formed may be used.

In addition, a replaceable chip-type recording head that can be electrically connected to the device main body or supplied with ink from the device main body by being attached to the device main body, or an ink tank integrated with the recording head itself The present invention is also effective when a cartridge-type recording head provided in a fixed manner is used.

The present invention provides a method of manufacturing a thin film transistor or an optical sensor array using a thin film transistor type optical sensor, wherein after the element isolation of each element, a step of roughening the exposed surface of the insulating substrate is added. Adhesion between the protective film and the protective film improves, and impurities do not penetrate through the gap between the protective film and the substrate, deteriorating device characteristics or corroding wiring. This greatly contributes to improved yield. I do.

[Brief description of the drawings]

1 (a) to 1 (g) are explanatory views showing an example of steps of the method of the present invention, FIG. 2 is a sectional view of an optical sensor array manufactured according to the method of the present invention, and FIG. FIG. 4 is a cross-sectional view of the case where the obtained optical sensor is applied to an image reading apparatus, FIG. 4 is a circuit diagram of a complete contact type sensor constituted by a semiconductor device obtained by the method of the present invention, FIG. FIG. 6 is a schematic configuration diagram showing an example of a facsimile having a communication function to which the optical sensor is applied,
FIG. 7 is a cross-sectional view of a thin film transistor manufactured by a conventional method, FIGS. 8 (a) to (f) are explanatory views showing manufacturing steps of the thin film transistor of FIG. 7, and FIG. 9 is manufactured by a conventional method. FIG. 2 is a cross-sectional view of the optical sensor. 31 is a glass substrate, 32 is a gate electrode, 33 is a gate insulating film,
34 is a photoconductive semiconductor film, 35 is an n ⁺ layer, 36 and 37 are upper electrodes, 3
8 is a resist layer, 40 is a protective layer.

Claims (2)

(57) [Claims] A step of laminating a plurality of layers for forming a plurality of semiconductor elements having electrodes on an insulating substrate; and a step of forming a plurality of layers for separating the semiconductor elements from each other. A method of manufacturing a semiconductor device, comprising: a removing step of removing a part of a layer; and a step of providing an insulating protective layer covering the element region on the insulating substrate. The surface of the insulating substrate is roughened by reactive ion etching or wet etching using a solution containing HF to a sufficient degree to increase the adhesion between the insulating substrate and the insulating protective layer. A method for manufacturing a semiconductor device, comprising: providing an insulating protective layer in contact with a planarized surface. 2. A semiconductor device comprising: an optical sensor including at least a photoconductor layer and a counter electrode; and a thin film transistor including at least a gate electrode, a gate insulating layer, a semiconductor layer, an ohmic contact layer, and source and drain electrodes. 2. The method for manufacturing a semiconductor device according to claim 1, wherein: