JP2741959B2 - Method of manufacturing thin film transistor array substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin film transistor (TFT) array substrate which is one substrate of an active matrix drive type liquid crystal display.

[0002]

2. Description of the Related Art FIG. 2 is a manufacturing process diagram showing a cross section of an example of a conventional method for manufacturing a TFT array substrate.

[0003] As shown in FIG.
First, a gate electrode 32 made of a metal such as Cr (chromium), Ta (tantalum), or Ti (titanium) is formed on a glass substrate 31 (S1). Next, the plasma CV
By using the D method, SiNx33 as a gate insulating film was set to 0.1.
An amorphous silicon (a-Si) film 34 as a semiconductor active layer is formed to a thickness of 1 μm to 0.5 μm.
An amorphous silicon (n ⁺ a-Si) film 35 doped with an impurity, which is an ohmic junction film, is formed to a thickness of 1 μm.
Films are sequentially formed to a thickness of from 02 μm to 0.05 μm, and are etched except for the TFT portion (S2). Next, Al
A metal layer such as (aluminum) and Cr is deposited, and a source electrode 36 and a drain electrode 37 are formed by etching (S3). Next, an n ⁺ a-Si film 35 between the source electrode 36 and the drain electrode 37 is controlled by a reactive ion etching apparatus using a mixed gas of CF ₄ and O ₂ as an etching gas to control the etching time. Was removed by etching (S4). Then, after etching,
When the off-current is large by measuring the characteristics of the FT, n + a
Since the -Si film 35 was considered to remain, the etching was performed again.

[0004]

However, in the above conventional manufacturing method, n ⁺ a-Si
The film 35 remains or a-Si
In some cases, the film 34 was removed to deteriorate the TFT characteristics.

[0005] In addition, plasma emission spectroscopy revealed that n ⁺ a-
Although it is conceivable to determine the end time of the etching by distinguishing the Si film 35 from the a-Si film 34, the n ⁺ a-Si film 35 may be used.
And the difference between the emission intensities of the a-Si film 34 and the
Use was difficult.

Accordingly, the present invention has been made to solve the above-mentioned problems, and has as its object the purpose of n ⁺
The a-Si film can be properly etched, and the T yield is good.
An object of the present invention is to provide a method for manufacturing an FT array substrate.

[0007]

Means for Solving the Problems The T according to the first aspect of the present invention.
The method of manufacturing an FT array substrate is based on the same insulating substrate,
A metal film for the gate electrode, an insulating film, an amorphous silicon film, and an ohmic junction film are formed in the same order in the thin film transistor part and the end point detection part simultaneously and in the same process,
Next, by forming a source electrode and a drain electrode on the ohmic junction film of the thin film transistor portion,
A thin film transistor portion having a metal film for a gate electrode, an insulating film, an amorphous silicon film, an ohmic junction film, a source electrode and a drain electrode; and an end point detecting portion having a metal film for a gate electrode, an insulating film, an amorphous silicon film and an ohmic junction film. Is formed, and then the substrate on which the thin film transistor section and the end point detection section are formed is installed in an etching apparatus including a light source having a spectrum in at least a visible region and a light intensity measuring device, and the etching apparatus uses the thin film transistor. When etching and removing the ohmic junction film located between the source electrode and the drain electrode of the portion, the ohmic junction film of the end point detection unit is also etched in the same step as the above, and at the time of the etching, from the light source Output, and the ohmic junction film and amorphous Light transmitted through the silicon film and the insulating film, reflected on the surface of the metal film for the gate electrode, and transmitted again through the insulating film, the amorphous silicon film, and the ohmic bonding film is received by the light intensity measuring device, and the light The etching is terminated when it is detected that the intensity of the light detected by the intensity measuring device has reached a predetermined value.

[0008]

According to the first aspect of the present invention , a metal film for a gate electrode, an insulating film, a non-doped amorphous silicon film, and an ohmic junction film are sequentially formed on the same insulating substrate on a TFT portion and an end point detecting portion, respectively. At the same time, they are formed in the same process, and after the source electrode and the drain electrode are formed on the ohmic junction film of the TFT part, the light source and the light intensity measuring device are used to transmit the ohmic junction film, the amorphous silicon film, and the insulating film. Then, the ohmic junction film is etched by an etching device while detecting the intensity of light reflected on the surface of the metal film for the gate electrode and transmitted again through each of the films. Then, when the intensity of the transmitted light reaches a predetermined value, the etching is terminated. As described above, in the present invention, the spectroscopy of the reflected and transmitted light in the end point detection unit formed simultaneously with the TFT unit on the same insulating substrate is performed.
Since the end point of the etching of the ohmic junction film located between the source electrode and the drain electrode of the TFT portion is determined while detecting the torque intensity , insufficient etching or etching over is unlikely to occur.

[0009]

FIG. 1 is a sectional view showing one embodiment of a method of manufacturing a TFT array substrate according to the present invention, and FIG. 3 is a structural view showing a plasma etching apparatus used in this embodiment. It is. Furthermore, FIG.
FIG.

Hereinafter, the manufacturing method of this embodiment will be described. As shown in S1 of FIG. 1, first, gate electrodes 2 and 12 made of a metal such as Cr, Ta, and Ti are formed on a transparent insulating substrate 1 such as a glass.

Next, insulating films 3 and 13 made of a SiNx film and a non-doped amorphous silicon (a-Si) film serving as a semiconductor active layer are formed on the insulating substrate 1 having the gate electrodes 2 and 12 by plasma CVD. 4 and 14 and phosphorus-doped amorphous silicon (n ⁺ a-Si) films 5 and 15 serving as ohmic junction films
And on the end point detection unit 20 in this order.

Next, a source electrode 6 and a drain electrode 7 made of a metal film such as Al or Cr are formed on the n ⁺ a-Si film 5 of the insulating substrate 1. Thereby, the TFT unit 10 and the end point detection unit 20 are formed on the same transparent insulating substrate 1.

Next, in order to remove the ohmic junction film located between the source electrode 6 and the drain electrode 7, that is, the n ⁺ a-Si film 5, the TFT section 10 and the plasma etching apparatus shown in FIG. The substrate 1 on which the end point detection unit 20 is formed is set. This plasma etching equipment
In a reaction chamber 21 into which an etching gas can be introduced, a cathode electrode 22 also serving as a mounting table for the insulating substrate 1 on which the TFT unit 10 and the end point detection unit 20 are formed, and a substantially true position of the end point detection unit 20
A light source 23 having a spectrum in the visible light region, such as a halogen lamp, located above , and an anode electrode 24 are provided. A window 25 through which light from the light source 23 passes is provided substantially directly above the end point detection unit 20, and a spectroscope 26 is also provided substantially directly above the window 25. Halogen lamp
Is reflected by the end point detection unit 20, and
26 is incident. The reaction chamber 21
Is connected to an exhaust pump 27, and an RF power supply 29 is connected to the cathode electrode 22 via a matching box 28.

Next, the interior of the reaction chamber 21 is evacuated by an exhaust pump 27, a mixed gas of CF ₄ and O ₂ is introduced as an etching gas, and RF power is supplied from an RF power source 29 to the cathode electrode 22 to generate plasma. Then, the n ⁺ a-Si films 5 and 15 are etched. At this time, the light from the light source 23 and the insulating film 13 of the
Transmitted through the Si film 14 and the n ⁺ a-Si film 15, once gate
Reflected by the gate electrode 12 and again the insulating film 13 and the a-Si film 1.
4 and the spectrum intensity of light transmitted through the n ⁺ a-Si film 15 are measured. And the spec of this reflected and transmitted light
The etching is terminated when it is detected that the torque intensity has reached a predetermined value.

FIG . 5 shows the transmittance of light detected by the spectroscope 26 .
FIG. 4 is a diagram showing a spectrum of FIG. In the figure, A is before etching, and B is in the middle of etching and is still n ⁺ a-.
When etching is insufficient with the Si film remaining, C is n
D indicates the case of proper etching in which the ⁺ a-Si film is completely removed, and D indicates the case of overetching in which the a-Si film as the lower layer of the n ⁺ a-Si film is etched. Therefore, if the etching is continued, the spectrum becomes
A, B, C, D proceed in this order.

In this embodiment, the end point detection unit 20 is turned off.
The edge film 13, the a-Si film 14 and the n ⁺ a-Si film 15 are transparent.
And is reflected once by the gate electrode 12 and again
And light transmitted through the a-Si film 14 and the n ⁺ a-Si film 15
Etching when the spectrum intensity of FIG.
To end. Then, the TFT section 10 of the substrate 1 and the n ⁺ a-Si films 5 and 15 of the end point detecting section 20 are removed as shown in S2 of FIG.

First, the gate electrodes 2 and 12 of the TFT section 10 are formed on the insulating substrate 1 and then the TFT section 10 is formed.
And the insulating films 3 and 13, the amorphous silicon films 4 and 14, and the phosphorus-doped amorphous silicon films 5 and 15 of the end point detection unit 20 are simultaneously formed in the same process, and then the source electrode is formed on the phosphorus-doped amorphous silicon film of the thin film transistor unit. And the drain electrode,
TFT unit 10 and end point detection unit 2 on the same insulating substrate 1
0, and then the reflection and transmission in the end point detection unit 20 are performed.
The phosphorus-doped amorphous silicon films 5 and 15 are etched by a plasma etching apparatus while detecting the passed light . Then, reflection and transmission in the end point detection unit 20
The etching is terminated when the spectral intensity of the light reaches a predetermined value. Thereby, the ohmic junction film (phosphorus-doped amorphous silicon film) located between the source electrode 6 and the drain electrode 7 is completely removed,
The amorphous silicon film 4 having a constant thickness remains. As described above, the end time of the etching is determined while detecting the change in the light transmittance of the insulating film, the amorphous silicon film, and the phosphorus-doped amorphous silicon film formed simultaneously with the TFT unit 20 on the same insulating substrate 1. Therefore, insufficient etching and over etching are eliminated.

[0018]

As described above, according to the present invention,
On the same substrate on which the TFT portion is formed, an end point detecting portion of a laminated structure including at least the same laminated structure as the insulating film, the amorphous silicon film, and the ohmic junction film constituting the TFT portion is formed , and reflection in the end point detecting portion is performed. And transmitted light
Etching the ohmic junction film while detecting
Determines the end point of etching by light emitted and transmitted
Less under-etching and over-etching
The production yield of thin film transistor array substrates.
Can be up.

Also, as in the present invention, the detection of the end point is reflected or detected.
And a conventional etch to do in the way with transmitted light
No need for any major changes in the structure of the
Also, there is an effect that the end point of the present embodiment can be detected.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram showing one embodiment of a method for manufacturing a TFT array substrate according to the present invention.

FIG. 2 is a manufacturing process diagram of a conventional TFT array substrate.

FIG. 3 is a configuration diagram of a plasma etching apparatus used for manufacturing the present embodiment.

FIG. 4 is an enlarged view of a main part of the embodiment.

FIG. 5 shows transmittance of light detected by a spectroscope in the present embodiment .
FIG. 4 is a diagram showing a spectrum of FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 insulating substrate 2 , 12 gate electrode 3, 13 insulating film 4, 14 amorphous silicon film 5, 15 non-doped amorphous silicon film 6 source electrode 7 drain electrode 10 thin film transistor section 20 end point detection section

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 29/786 (72) Inventor Mari Shimizu 1-7-12 Toranomon, Minato-ku, Tokyo Inside Oki Electric Industry Co., Ltd. (56) References JP-A-3-3345 (JP, A) JP-A-62-176132 (JP, A)

Claims (1)

(57) [Claims] A metal film for a gate electrode, an insulating film, an amorphous silicon film, and an ohmic junction film are formed simultaneously and in the same process on a thin film transistor portion and an end point detecting portion on the same insulating substrate. Forming a source electrode and a drain electrode on the ohmic junction film of the thin film transistor section, thereby forming a thin film transistor section having a gate electrode metal film, an insulating film, an amorphous silicon film, an ohmic junction film, a source electrode and a drain electrode. And an end point detection unit having a metal film for a gate electrode, an insulating film, an amorphous silicon film, and an ohmic junction film, and then in an etching apparatus provided with a light source having a spectrum in at least a visible region and a light intensity measuring device. The substrate on which the thin film transistor section and the end point detection section are formed is installed When the etching apparatus removes the ohmic junction film located between the source electrode and the drain electrode of the thin film transistor portion by etching, the ohmic junction film of the end point detection unit is also etched in the same step as the etching process. At this time, the light is output from the light source, passes through the ohmic junction film, the amorphous silicon film, and the insulating film of the end point detection unit, is reflected on the surface of the metal film for the gate electrode, and further is the insulating film, the amorphous silicon film, and the ohmic junction film. And the light transmitted again is received by the light intensity measuring device, and the intensity of the light detected by the light intensity measuring device is
A method for manufacturing a thin film transistor array substrate, comprising: terminating the etching when it is detected that a predetermined value is reached.