JPH04298046A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor manufacturing method that prevents contamination of a semiconductor device in a lift-off process while reducing the damage to the channel section of the device due to high-energy rays. CONSTITUTION:First and second insulating films 23 and 24 having the same pattern are formed on a semiconductor layer 22. The second insulating film 24 is used for lifting the subsequent film 25 off. The first insulating film 23 serves as a buffer against high-energy rays 26 applied in a later process and serves to protect the interface with the semiconductor layer 22.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The method for manufacturing a semiconductor device of the present invention includes:
This field relates to patterning in thin film transistors and process technology using high energy beams.

0002

2. Description of the Related Art In recent years, thin film transistors have been applied to many products due to improved reliability due to the use of silicon-based materials.

In particular, polycrystalline silicon is widely used as a semiconductor material because it provides high electron mobility, which is important for the performance of thin film transistors. Methods for producing polycrystalline silicon include, in addition to forming it by thermal CVD, a method in which amorphous silicon is polycrystallized by irradiating it with high-energy rays such as a laser beam.

FIG. 7 is a step-by-step device structure diagram for explaining a conventional method for manufacturing a thin film transistor using polycrystalline silicon. In the process shown in FIG.
1) After forming a film of intrinsic amorphous silicon (2) on top, patterning a photoresist (3) made of an organic material,
After that, phosphorus (P)-doped amorphous silicon (4
) to form.

Next, in the step shown in FIG. 3(b), the photoresist (3) is removed.
3) The amorphous silicon (4) above is removed by lift-off and patterned.

In the step shown in FIG. 2(c), a laser (5) is irradiated onto the intrinsic amorphous silicon (2) and the phosphorous-containing amorphous silicon (4) on the substrate (1), thereby Becomes polycrystalline. Intrinsic amorphous silicon (2) on which amorphous silicon (4) is superimposed has amorphous silicon (2) during its polycrystallization.
The phosphorus contained in 4) is intrinsic amorphous silicon (2)
and becomes n-type polycrystalline silicon (6). On the other hand, the portion of the intrinsic amorphous silicon (2) on which the amorphous silicon (4) is not laminated becomes intrinsic polycrystalline silicon (7) because such diffusion does not occur. The n-type polycrystalline silicon (6) becomes an ohmic contact region of the thin film transistor in a later step.

In the step shown in FIG. 2D, a silicon oxide film (8) as a gate insulating film and a passivation film as a thin film transistor, a gate electrode (9), a source electrode (10), and a drain electrode (11) are formed.
) to form.

As described above, according to the conventional manufacturing method, the lift-off and diffusion of impurity elements by laser irradiation form a fine channel length and form ohmic contacts in the source and drain regions. There is.

[0009] Regarding such a conventional example, the Applied Electronic Materials Subcommittee Research Report No. 432. It is described in detail on pages 31 to 36 (Japan Society of Applied Physics, January 12, 1990).

0010

[Problems to be Solved by the Invention] However, the conventional manufacturing method described above has various problems.

First of all, the photoresist (3) made of an organic material is introduced into the forming apparatus during the formation of the amorphous silicon (4), causing contamination within the apparatus. This also contaminates the semiconductor device itself, causing deterioration of its characteristics.

Second, the chemical for removing the photoresist (3) attacks the surface of the amorphous silicon adhered to the photoresist (3) during lift-off, and the interface formed on the surface is This will cause the characteristics to deteriorate.

Thirdly, in the process of polycrystallizing amorphous silicon by laser irradiation, the laser is irradiated almost uniformly to the channel portion, source, and drain portions, so that each portion is It is not possible to perform irradiation with appropriate intensity.

Fourthly, when a semiconductor is irradiated with a high-energy beam such as a laser beam, the surface of the semiconductor becomes rough, and even if a high-quality gate insulating film is formed on the surface, it is difficult to obtain good interface characteristics. I can't.

In view of the above, the purpose of the manufacturing method of the present invention is to prevent contamination of the semiconductor device during the lift-off process and to reduce damage to the channel portion due to irradiation with high-energy rays. An object of the present invention is to provide a method for manufacturing a device.

[0016]

[Means for Solving the Problems] The method for manufacturing a semiconductor device of the present invention is characterized in that a semiconductor layer is formed on a substrate, and a first insulating film having the same pattern shape is formed on the semiconductor layer. , forming a second insulating film having a different composition from the first insulating film in this order; and forming a conductive film on the surface of the semiconductor layer so that the first and second insulating films are included. forming a film containing type-determining impurities;
a step of removing the film deposited on the insulating film by lift-off; and a step of irradiating the first insulating film and the film with high-energy radiation. The method for manufacturing a semiconductor device of the present invention is characterized in that a semiconductor layer is formed on the main surface of a substrate, and a first insulating layer having the same pattern shape is formed on the semiconductor layer. a step of forming, in this order, a laminate consisting of a film, a metal film, and a second insulating film having a composition different from that of the first insulating film; forming a film containing a conductivity type determining impurity, and removing the second insulating film,
The method includes the steps of removing the film deposited on the insulating film by lift-off, and irradiating the metal film and the film with high-energy radiation from the main surface side.

[0017]

[Operation] According to the manufacturing method of the present invention, first and second semiconductor layers having the same pattern shape are formed on a semiconductor layer formed on a substrate.
form an insulating film. As a result, the second insulating film can be used as a lift-off material for a film containing conductivity type determining impurities that will be formed in a later process, and the first insulating film can be For energy rays,
Polycrystalline conditions for the amorphous semiconductor located below the insulating film are moderated.

Furthermore, by disposing a metal film between the first and second insulating films, it is possible to prevent the amorphous semiconductor from being irradiated with high-energy rays.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are element structure diagrams for each manufacturing process of a semiconductor device, which is a first embodiment of the manufacturing method of the present invention.

In the step shown in FIG. 1(a), reduced pressure C is applied onto one main surface of a substrate (21) made of quartz, ceramics, etc.
Semiconductor layer (22) made of amorphous silicon by VD method
1000 Å thick, a first insulating film (23) made of silicon nitride film formed by plasma CVD method.
A second insulating film (24) made of a silicon oxide film having a composition different from that of the first insulating film (23) is formed with a thickness of 200 Å, respectively.
The layers are sequentially formed to a thickness of 1 μm.

In the step shown in FIG. 2(b), amorphous silicon doped with phosphorus, which is a conductivity type determining impurity, is formed to include a first insulating film (23) and a second insulating film (24). A film (25) having a thickness of 300 Å is formed on the semiconductor layer (22) by plasma CVD.

According to this process, since a conventional photoresist made of an organic material is not used as an insulating film, the plasma CVD equipment used to form the film (25) is free from contamination due to the organic material, and at the same time This makes it possible to improve the reliability of the semiconductor device.

Next, in the step shown in FIG. 4C, the second insulating film (24) is removed and the film (25) is patterned by lift-off.

[0024] The silicon oxide film and the silicon nitride film are
Selective etching can be easily performed by wet etching or dry etching, and in particular, this selective etching can be easily performed by making the first insulating film and the second insulating film have different compositions. be able to.

[0025] In this step, the etching solution for the second insulating film (24) used in this lift-off is such that the semiconductor layer (22) is covered with the first insulating film (23). Therefore, it does not come into direct contact with the semiconductor layer (22) and does not damage the semiconductor layer.

In the step shown in FIG. 2(d), a high energy beam (26) such as an excimer laser is emitted from the main surface side.
is irradiated to polycrystallize the film (25) and the semiconductor layer (22), and at the same time, the phosphorus contained in the film (25) is diffused into the semiconductor layer (22).

Through this step, the laminated portion of the semiconductor layer (22) and the film (25) becomes a phosphorous-doped polycrystalline semiconductor (27) (27), and the first insulating film (
The semiconductor layer (22) located below 23) becomes an intrinsic polycrystalline semiconductor (28). Note that in this step, the polycrystalline semiconductor (28), which will become a channel portion in a later step, will be irradiated with the high-energy rays (26) through the first insulating film (23). The irradiation conditions are milder than that of the polycrystalline semiconductor (27).

Furthermore, this means that the insulating film (23)
A good semiconductor-insulator junction can be formed without causing roughness due to the high-energy rays at the interface between the polycrystalline semiconductor (28) and the polycrystalline semiconductor (28).

In the step shown in FIG. 2(e), a gate insulating film (29) is formed on the first insulating film (23) so that the lower part of the first insulating film (23) becomes a channel part.
form. This insulating film (29) can also be used not only as a gate but also as a passivation film (30).

In the step shown in FIG. 3(f), a drain electrode (31) and a source electrode (32) are formed on the polycrystalline semiconductor (27), and a gate electrode (32) is formed on the gate insulating film (29). 33), a metal film made of chromium or aluminum was formed by vapor deposition.

According to such a manufacturing method, the reliability of the device itself can be improved because the semiconductor device is not contaminated by the organic material as described above, and the second semiconductor device used for lift-off can be improved. Since the insulating film and the first insulating film, which functions as a shock absorber during high-energy beam irradiation, have the same pattern shape, it is possible to meet the requirements for microfabrication of the channel portion.

FIGS. 3 and 4 are element structure diagrams for each manufacturing process of a semiconductor device, which is a second embodiment of the manufacturing method of the present invention.

This example differs from the first example only in that a metal film is interposed between the first insulating film and the second insulating film. The process steps are as follows.

In the step shown in FIG. 3(a), a semiconductor layer (42) made of amorphous silicon is formed by low pressure CVD on a substrate (41) made of quartz, and then a semiconductor layer (42) made of a silicon nitride film is formed. A first insulating film (43), a metal film (44) made of chromium, and a second film made of silicon oxide.
A laminate is formed by sequentially depositing insulating films (45).

In this example, the silicon nitride film and silicon oxide film are formed by the plasma CVD method, and their film thicknesses are 200 Å and 1 μm, and the metal film (44) is 200 Å thick.

Next, in the step shown in FIG. 4B, a film (46) made of amorphous silicon doped with phosphorus, which is a conductivity type determining impurity, is formed on the semiconductor layer (42) so as to include this stacked body. ) is formed by plasma CVD method.

In the step shown in FIG. 4C, the second insulating film (45) is removed and the film (46) is patterned by lift-off.

In the step shown in FIG. 4(d), the semiconductor layer (42) and the film (46) are polycrystallized by irradiating the film-forming surface with a high-energy laser beam (47). In this example as well, the laminated portion of the semiconductor layer (42) and the film (46) is
Although the phosphorus-doped polycrystalline semiconductor (48) is the same as the first example, the feature of this example is that the metal film (48) is formed on the first insulating film (43).
4), even if the high energy rays (47) are irradiated, they will not reach the semiconductor layer (42) and will remain in the initial amorphous semiconductor (42a) state. Become.

Finally, in the step shown in FIG. 4(e), after removing the metal film (44), the gate insulating film (49), gate metal film (50), and source film are removed as in the first embodiment. A metal film (51) and a drain metal film (52) are formed.

According to this example, in addition to being able to prevent the occurrence of contamination due to not using an organic material as a lift-off, the first insulating film, the second insulating film, and the metal film have the same shape. Because it is formed with a pattern of have.

In particular, when an amorphous semiconductor is used for the channel portion, the characteristic of high resistance of the amorphous semiconductor can be utilized, and as a result, leakage current when the thin film transistor is turned off can be reduced.

FIGS. 5 and 6 are process-by-step element structure diagrams of a semiconductor device which is a third embodiment of the manufacturing method of the present invention.

In the step shown in FIG. 5(a), a semiconductor layer (62) made of amorphous silicon is formed on one main surface of a transparent insulating substrate (61) by plasma CVD, and then a first After the insulating film (63), the metal film (64), and the second insulating film (65) are sequentially laminated, they are patterned to have the same shape. The semiconductor layer (62) has a thickness of 1000 Å, and the other insulating films (63) (65) and metal film (64) each have a thickness of 500 Å.

In the step shown in FIG. 6(b), a high energy beam (66) from a laser is irradiated from the side where the film is formed, and the semiconductor layer (62) exposed on the surface is transformed into a polycrystalline semiconductor (67).
). In such a process, the first insulating film (
63) and the portion of the semiconductor (62a) covered with the metal film (64) is not irradiated with high energy rays, so polycrystallization does not occur.

Next, in the step shown in FIG. 3(c), a film doped with phosphorus, which is a conductivity type determining impurity, is formed to a thickness of 300 Å.
A film (68) made of amorphous silicon is formed. In this case, by reducing the thickness of this film (68), at the boundary of the pattern formed by the laminate of the first and second insulating films and the metal film, the layer is (68) film breakage occurs.

In particular, in this example, since the metal film (64) is used as the gate metal film of this semiconductor device, the film (64) is used as the gate metal film of this semiconductor device.
It is important to form the first insulating film (63) sufficiently thick so that the metal film (68) and the metal film (64) are not electrically connected.

Then, in the step shown in FIG. 6(d), the second
By removing the insulating film (65), the film (68) deposited on the insulating film is removed by lift-off, and this film (68) is patterned.

Next, in the step shown in the same figure (e), the substrate (
61) A high-energy beam (69) is irradiated from the other main surface to polycrystallize the polycrystalline semiconductor (67), the film (68), and the portion of the semiconductor (62a) that was not polycrystallized in the previous step. I do. In particular, in this step, phosphorus in the film (68) diffuses into the polycrystalline semiconductor (67) at the same time as this polycrystallization, imparting conductivity to the polycrystalline semiconductor (67) laminated with the film (68). I will have to have it. The polycrystalline semiconductor in these parts will be used as a source region (70) and a drain region (70) in a later process.
1) It functions as an ohmic contact part.

Finally, in the step shown in FIG. 6(f), metal electrodes are formed to correspond to the source region (70) and drain region (71), and the source electrode (72) and drain electrode (73) are shall be.

This third embodiment lifts the organic material.
In addition to being able to prevent the above-mentioned contamination by not using it as an off-state, polycrystallization of the semiconductor layer in the channel region is performed by high-energy ray irradiation separately from polycrystallization of the source and drain regions. Therefore, it becomes possible to irradiate the channel portion with an energy intensity suitable for the channel portion.

Furthermore, this example has the feature that the metal film disposed between the first and second insulating films can be used as a gate metal film of a semiconductor device.

However, the effects of the manufacturing method of the present invention are not necessarily achieved only by using this metal film as a gate metal film, and the use of this metal film as a film for blocking irradiation during irradiation with high-energy rays does not necessarily mean that the effect of the manufacturing method of the present invention is exhibited only by using this metal film as a gate metal film. Needless to say, this may be removed afterwards and a new gate metal film may be formed. In this case, the first insulating film does not need to be as thick as in this example, and may be a relatively thin film as in the first embodiment.

In each of the embodiments described above, amorphous silicon was used as the semiconductor layer formed on the substrate, but the present invention is not limited to this, and for example, a polycrystalline semiconductor layer may be used. That is, since the semiconductor layer formed initially will function as the channel part of the semiconductor device, a polycrystalline semiconductor layer optimal for the channel part is formed in advance from the beginning, and even if subsequent steps are performed, good.

In such a case, in the first embodiment, since the first insulating film is deposited on this polycrystalline semiconductor layer, the high-energy rays irradiated during the process may cause damage. In the case of the second embodiment, since the metal film is included in addition to the first insulating film, the influence can be alleviated.
This has no effect on this polycrystalline semiconductor layer. Furthermore, the third
In this embodiment, the high-energy ray irradiation from the film formation side has no effect as in the second embodiment, and the irradiation from the side opposite to the film formation side does not affect the polycrystalline semiconductor layer. There is no need to do this since it is already optimal.

In the embodiment, as the high energy beam, in addition to a laser, an electron beam, an infrared ray, an ion beam, etc. can also be used. Further, in the embodiment, amorphous silicon containing phosphorus was used as the film containing the conductivity type determining impurity, but the present invention is not limited to this, and boron or the like may be used as the impurity. Furthermore, a spin-on source made of silicon glass or polycrystalline silicon containing conductivity type determining impurities may be used.

[0056]

[Effects of the Invention] According to the method of manufacturing a semiconductor device of the present invention,
Since the conventionally used photoresist made of an organic material is not used as a lift-off, no contamination is caused by this.

Furthermore, since the insulating film for lift-off and the insulating film for mitigating the irradiation of high-energy rays have the same pattern shape, miniaturization can be achieved when forming the channel portion.

Furthermore, even if the amorphous semiconductor layer is irradiated with high-energy rays, damage caused by the high-energy rays is reduced because the surface of the amorphous semiconductor layer is protected by the insulating film.

In addition, by interposing a metal film between the first and second insulating films, it is possible to prevent the channel portion from being irradiated with high-energy rays. Therefore, a polycrystalline semiconductor layer or an amorphous semiconductor layer suitable for the channel portion can be used.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an element structure by step for explaining a method of manufacturing a semiconductor device according to the present invention.

FIG. 2 is a cross-sectional view of an element structure in another step for explaining the method for manufacturing the semiconductor device.

FIG. 3 is a cross-sectional view of an element structure by step for explaining a method of manufacturing a semiconductor device according to the present invention.

FIG. 4 is a cross-sectional view of an element structure in another step for explaining the method for manufacturing the semiconductor device.

FIG. 5 is a cross-sectional view of an element structure by step for explaining a method of manufacturing a semiconductor device according to the present invention.

FIG. 6 is a cross-sectional view of an element structure in another step for explaining the method for manufacturing the semiconductor device.

FIG. 7 is a cross-sectional view of an element structure by step for explaining a conventional method of manufacturing a semiconductor device.

[Explanation of symbols]

(21)---Substrate (22) ---Semiconductor layer (23) ---first insulating film (24) ---Second insulating film (25) ---membrane (26)──High energy rays

Claims (2)

[Claims] 1. A semiconductor layer is formed on a substrate, a first insulating film having the same pattern shape on the semiconductor layer,
forming a second insulating film having a different composition from the first insulating film in this order; and forming a conductive layer on the surface of the semiconductor layer so that the first and second insulating films are included a step of forming a film containing a determined impurity; a step of removing the film deposited on the insulating film by removing the second insulating film; and a step of removing the film deposited on the insulating film by lift-off; A method for manufacturing a semiconductor device, comprising the steps of: irradiating an insulating film and the film with high-energy rays. 2. A semiconductor layer is formed on the main surface of a substrate, a first insulating film, a metal film having the same pattern shape on the semiconductor layer, and a second insulating film having a composition different from that of the first insulating film. 2
forming, in this order, a laminate consisting of an insulating film, a step of forming a film containing a conductivity type determining impurity on the surface of the semiconductor layer so as to include the laminate, and the second insulating film. a step of removing the film deposited on the insulating film by lift-off, and a step of irradiating the metal film and the film with high energy rays from the main surface side. A method for manufacturing a semiconductor device, comprising the steps of: