JP3237642B2 - Polycrystalline silicon thin film transistor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycrystalline silicon thin film transistor and a method of manufacturing the same, and more particularly, to a polycrystalline silicon thin film transistor capable of reliably performing a hydrogenation process and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional thin film transistor has a base insulating film 22 (film thickness 50) on a glass substrate 21.
0 nm) and the polycrystalline silicon layer 23 (75 nm thick)
Then, a gate insulating film 24 (about 100 nm in thickness) and a gate electrode 25 (about 100 nm in thickness) are formed, and impurities such as phosphorus and boron are implanted using the gate electrode 25 as a mask.
Source and drain regions 23a and 23c are formed.
Then, after annealing for activating the impurities, hydrogenation is performed as shown in FIG. 6 to reduce the defect density of the polysilicon layer 23b. Thereafter, as shown in FIG. 7, an interlayer insulating film 26 (with a thickness of about 400 nm) is deposited on the entire surface, contact holes 27 are opened in the interlayer insulating film 26, and source and drain electrodes 28 are formed.

Since the gate electrode 25 is used as a mask during the hydrogen treatment, it is difficult for hydrogen to reach the region 23b under the gate. Therefore, dangling bonds of the polycrystalline silicon layer under the gate are not sufficiently terminated. In addition, there is a problem that the defect density is increased and the performance of the thin film transistor is limited. In addition, since hydrogen terminating dangling bonds of the polycrystalline silicon gradually diffuses outward, there is a defect that the defect density of the polycrystalline silicon layer 23b gradually increases and reliability is limited.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned disadvantages of the prior art, and in particular, to compensate for the insufficient hydrogenation of a polycrystalline silicon layer which is an active layer of a thin film transistor.
It is another object of the present invention to provide a novel polycrystalline silicon thin film transistor capable of reliably performing hydrogenation treatment by preventing outward diffusion of hydrogen from a polycrystalline silicon layer, and a method of manufacturing the same.

[0005]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object. That is, state-like polycrystalline silicon thin film transistor according to the present invention, the polycrystalline silicon layer is deposited on a glass substrate, and the drain and source regions in which impurities are introduced into the polycrystalline silicon layer,
A polycrystalline silicon thin film transistor including a channel region formed between the drain region and the source region, and a gate electrode provided on the channel region; a hydrogen supply layer under the channel region of the polycrystalline silicon thin film transistor; forming Then co the outward diffusion preventing layer of the formed hydrogen to cover the hydrogen supplying layer
In addition, the hydrogen supply layer and the outward diffusion prevention layer, the glass
Ru der those characterized by being formed in a recess provided on the back surface of the substrate.

Further, the polycrystalline silicon thin film according to the present invention
Manufacturing method of transistorState ofLike polycrystalline on a glass substrate
A silicon layer is formed, and impurities are added to the polycrystalline silicon layer.
A drain region and a source region into which
Channel region formed between In region and Source region
And a gate electrode provided on this channel region
Polycrystalline silicon thin film transistor for hydrogenation
In the method of manufacturing the star,The polycrystalline silicon thin film tiger
At the lower part of the channel region of the transistor and the glass substrate
A first step of forming a recess on the back surface of the plate;SaidIn the recess
First, a hydrogen supply layer is formed.2And the stepIn the recess
DepositedTo cover the hydrogen supply layer,Prevention of outward diffusion of hydrogen
The first to form a layer3Characterized by including the steps of
InYou.

[0007]

DETAILED DESCRIPTION OF THE INVENTION A polycrystalline silicon thin film transistor according to the present invention has a polycrystalline silicon layer formed on a glass substrate, and a drain region and a source region in which impurities are introduced into the polycrystalline silicon layer; A polycrystalline silicon thin film transistor comprising: a channel region formed between the region and the source region; and a gate electrode provided on the channel region. And a hydrogen diffusion preventing layer formed so as to cover the layer.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a polycrystalline silicon thin film transistor according to the present invention and a method of manufacturing the same. 1 to 5 are views showing the structure of a polycrystalline silicon thin film transistor according to the present invention and a specific example of a method of manufacturing the same. In these figures, a polycrystalline silicon layer 4 is formed on a glass substrate 1. A drain region 4a and a source region 4c in which impurities are introduced into the polycrystalline silicon layer 4, a channel region 4b formed between the drain region 4a and the source region 4c, and a gate provided on the channel region 4b. In the polycrystalline silicon thin film transistor including the electrode 6, the polycrystalline silicon thin film transistor has a channel region 4 b below the polycrystalline silicon thin film transistor,
A polycrystalline silicon thin film transistor formed with a hydrogen supply layer 9 and a hydrogen out-diffusion prevention layer 10 formed so as to cover the hydrogen supply layer 9 is shown. The prevention layer 10 is a polycrystalline silicon thin film transistor formed in a recess 8 provided on the back surface of the glass substrate 1.

Hereinafter, the present invention will be described in more detail. The polycrystalline silicon thin film transistor of this specific example has a base insulating film 3 (thickness: 500 n) formed on the surface side of the glass substrate 1.
m), and a polycrystalline silicon layer 4 (thickness: 75 nm) formed on the base insulating film 3. The polycrystalline silicon layer 4 includes regions 4a and 4c into which impurities are introduced, Region 4b is formed in which is not introduced. A gate insulating film 5 (100 nm thick), a gate electrode 6 (100 nm thick) and an interlayer insulating film 7 are formed on the polycrystalline silicon layer 4.
(Thickness: 400 nm), contact holes 12 are formed in the gate insulating film thickness 5 and the interlayer insulating film thickness 7, and the source and drain electrodes 13 are formed in the contact holes 12.
And regions 4a and 4c into which the impurities are introduced, respectively. A back surface hole (recess) 8 is formed on the back surface side of the glass substrate 1, and a hydrogen supply layer 9 is formed in the back surface hole 8.
And a hydrogen out-diffusion preventing layer 10 is formed.

The thin film transistor of the present invention controls the current flowing between the source electrode and the drain electrode by the voltage applied to the gate electrode 6 as in the case of the ordinary thin film transistor. Next, a method for manufacturing the thin film transistor of the present invention will be described. First, as shown in FIG. 2, an amorphous silicon film (having a thickness of about 100 nm) is formed as a back surface hole etching stopper layer 2 on a glass substrate 1. A base insulating film 3, for example, a silicon oxide film (about 500 nm in thickness) and a polycrystalline silicon layer 4 (about 75 nm in thickness) are formed thereon. Next, a gate insulating film 5, for example, a silicon oxide film (about 100 nm in thickness), and a gate electrode 6 (about 100 nm in thickness) are formed on the silicon oxide film. Then, using the gate electrode 6 as a mask, impurities such as phosphorus and boron are implanted to form the source and drain regions 4a and 4c. Next, after annealing is performed to activate the impurities, hydrogenation is performed to reduce the defect density of the polycrystalline silicon layer 4b. Next, an interlayer insulating film 7, for example, a plasma silicon nitride film (thickness: about 400 nm) is formed on the entire surface.
Is deposited.

Next, as shown in FIG. 3, the glass substrate 1 is turned upside down, a resist 15 is applied to the back surface to mask portions other than the back surface holes, and the glass substrate is etched to form the back surface holes 8. For the etching, for example, reactive ion etching excellent in anisotropy and selectivity is used, and etching is performed so as to be stopped by the back hole etching stopper layer 2. Next, the resist 15 is removed, and a hydrogen supply layer 9 containing a large amount of hydrogen, for example, a plasma silicon nitride film is deposited at least 1 μm as shown in FIG. Further, a hydrogen stopper layer 10 for preventing outward diffusion of hydrogen, for example, tungsten silicide, chromium, aluminum or the like (thickness: about 200 nm) is deposited thereon. This hydrogen stopper layer 10 can also serve as a light shielding film. Next, FIG.
An unnecessary portion of the hydrogen stopper layer is removed as described above, and a cover film 11, for example, an organic film such as BCB is deposited.
The glass substrate 1 is heated to about 300 ° C., and annealing is performed to diffuse hydrogen from the hydrogen supply layer 9 into the polycrystalline silicon layer 4b.

Next, the glass substrate 1 is turned over again, and a contact hole 12 is opened on the front surface side as shown in FIG. In the thin film transistor configured as described above, when the glass substrate 1 deposited up to the cover film 11 is annealed, hydrogen diffuses from the hydrogen supply layer 9 shown in FIG.
Terminates dangling bonds that were not terminated due to insufficient hydrogenation of b,
A high-performance thin film transistor with a reduced defect density in the polycrystalline silicon layer 4b can be expected.

Although hydrogen terminating dangling bonds in the polycrystalline silicon gradually diffuses outward, the diffusion of hydrogen from the polycrystalline silicon layer 4 to the glass substrate 1 depends on the supply of hydrogen containing a large amount of hydrogen. Blocked by layers. As described above, since outward diffusion of hydrogen from the polycrystalline silicon layer 4 is prevented, reliability is improved over a long period of time.

[0014]

As described above, the polycrystalline silicon thin film transistor and the method of manufacturing the same according to the present invention compensate for the insufficient hydrogenation of the polycrystalline silicon layer which is the active layer of the thin film transistor. This prevents hydrogen from being diffused outwards, thereby enabling reliable hydrogenation.

In addition, since the configuration is simple, it has excellent features such as easy implementation.

[Brief description of the drawings]

FIG. 1 is a sectional view of a polycrystalline silicon thin film transistor according to the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the polycrystalline silicon thin film transistor of the present invention.

FIG. 3 is a sectional view of a step following that of FIG. 2;

FIG. 4 is a sectional view of a step following that of FIG. 3;

FIG. 5 is a sectional view of a step following that of FIG. 4;

FIG. 6 is a cross-sectional view of a conventional polycrystalline silicon thin film transistor.

FIG. 7 is a sectional view of a step following FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Back hole etching stopper layer 3 Base insulating film 4 Polycrystalline silicon layer 4a Polycrystalline silicon layer (impurity introducing region) 4b Polycrystalline silicon layer 4c Polycrystalline silicon layer (impurity introducing region) 5 Gate insulating film 6 Gate electrode Reference Signs List 7 Interlayer insulating film 8 Backside hole (recess) 9 Hydrogen supply layer 10 Hydrogen stopper layer (outward diffusion prevention layer) 11 Cover film 12 Contact hole 13 Source / drain electrode

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 29/786 H01L 21/336

Claims (2)

(57) [Claims] A drain region and a source region in which a polycrystalline silicon layer is formed on a glass substrate and an impurity is introduced into the polycrystalline silicon layer; and a channel region formed between the drain region and the source region. A polycrystalline silicon thin film transistor including a gate electrode provided on the channel region, wherein a hydrogen supply layer is formed under the channel region of the polycrystalline silicon thin film transistor, and a hydrogen film is formed to cover the hydrogen supply layer. To form a diffusion prevention layer
The hydrogen supply layer and the outward diffusion preventing layer are
A polycrystalline silicon thin film transistor formed in a concave portion provided on a back surface . (2)Polycrystalline silicon layer formed on glass substrate
And a drain in which impurities are introduced into the polycrystalline silicon layer.
In region and source region, and the drain region and source
The channel area formed between the areas and this channel
Consisting of a gate electrode provided on the
Of a polycrystalline silicon thin film transistor
And Channel region of the polycrystalline silicon thin film transistor
Forming a recess at the bottom and on the back surface of the glass substrate
A first step; A second step of forming a hydrogen supply layer in the recess, In order to cover the hydrogen supply layer formed in the recess,
A third step of forming an outward diffusion preventing layer; Polysilicon thin film transistor characterized by containing
Manufacturing method.