JPH05167016A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To equalize the grain size of polycrystal silicon by a method wherein an amorphous silicon film formed to be heat-treated is recrystalized to be turned into a polycrystal silicon. CONSTITUTION:Poly-Si is deposited on a LOCOS oxide film 1 to form a poly-Si film 2. Next, the whole surface is implanted with BF2<+> in concentration corresponding to specified resistivity. Successively, the whole surface is implanted with Si<+> by low temperature ion implanting method. Through these procedures, the poly-Si film 2 is made almost amorphous to form an -Si film 2a. Next, this film 2a is cut out in specific shape to form an alpha-Si film pattern 2b. Later, SiO2 is deposited to form an SiO2 film 5. Successively, the whole body is annealed to recrystallize and crystalize the alpha-Si film pattern 2b for turning into poly-Si 6. Through these recrystallizing method by annealing step, the grain size of poly-Si 6 can be almost equalized thereby enabling the fluctuation in the resistivity to be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to polycrystalline silicon (polysilicon: poly: silicon) having a uniform grain size (grain size) of silicon (Si) to reduce fluctuations in resistivity. The present invention relates to a semiconductor device using Poly-Si) and a manufacturing method thereof.

[0002]

Polysilicon is often used as a gate electrode in MOS devices, but is also used as a resistor. Since this Poly-Si resistor can be selectively deposited and formed on the insulating film by a low pressure CVD method that thermally decomposes silicon, it has advantages such as miniaturization, small parasitic capacitance, and large substrate bias effect resistance. . Therefore, compared with a diffusion resistor formed by utilizing the diffusion of impurities into single crystal silicon (Single Si),
Si resistors are advantageous and widely used.

On the other hand, a poly-Si resistor has a line width, a film thickness, an impurity concentration to be introduced, a grain size (grain size), a grain boundary (grain boundary) and the like resistance value of the formed poly-Si film. Since there are many parameters that determine, it is disadvantageous in terms of resistance accuracy.

Among the parameters that determine the resistance value, the grain size is grown (coarsened) by the heat treatment during the manufacturing process.

The grain growth of Poly-Si depends on the crystallinity before the growth, but it is difficult to control the crystallinity and the resistance value varies.

[0006]

The grain size can be made uniform by recrystallizing amorphous silicon.

Conventionally, there is known a technique of partially implanting an ion into a Si layer such as polysilicon by implanting (II) certain ions into an amorphous layer. However, the amorphous layer thus formed has a structure containing many crystal defects and cannot be said to be a completely amorphous layer. Therefore, conventionally, it has been difficult to improve the accuracy of the resistivity from the viewpoint of controlling the grain size.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor device having a Poly-Si resistor in which the fluctuation of the resistivity is reduced from the viewpoint of controlling the grain size of Poly-Si, and a manufacturing method thereof.

[0009]

According to the present invention, in the semiconductor device having a resistor made of polycrystalline silicon, the grain size of the polycrystalline silicon is made uniform to reduce the variation in resistivity. The problem is solved by a semiconductor device characterized by being hampered.

Further, according to the present invention, in the method for manufacturing a semiconductor device having a resistor made of polycrystalline silicon, a step of forming a polycrystalline silicon film on an insulating substrate; A step of implanting a predetermined amount of impurity ions into the substrate, a step of implanting silicon at a low temperature of −50 ° C. or lower to change the polycrystalline silicon film into an amorphous silicon film, and patterning the amorphous silicon film into a predetermined shape. A method for manufacturing a semiconductor device is characterized by including a step of forming an interlayer insulating film on the entire surface after formation, and a step of recrystallizing the amorphous silicon film by heat treatment to convert it into polycrystalline silicon. It

[0011]

According to the present invention, the polysilicon (Poly-Si) which constitutes the resistor is once exposed to Si ions at a low temperature of -50 or less (about 200 ° C. is most preferable from the viewpoint of amorphization and practical workability). Since (Si ⁺ ) is injected, Poly-Si changes into almost amorphous silicon (a-Si). At a high temperature of −50 ° C. or higher, defects such as generation of voids and polycrystalline silicon not being completely amorphized occur.

Therefore, if a heat treatment for recrystallization is performed thereafter, each crystal growth rate from the amorphous state becomes almost constant, so that Poly-Si obtained after the heat treatment is obtained.
The grain size of is almost uniform. As described above, since Poly-Si having a substantially uniform grain size can be obtained, one of the factors that cause the change in resistivity can be controlled.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows polycrystalline silicon (Po) according to the present invention.
FIG. 4 is a cross-sectional view showing an example of a ly-Si) resistor.

As shown in FIG. 1, the resistor of the present embodiment is
Poly-S is formed on the LOCOS oxide film 1 made of SiO _2.
i6. Electrodes 10a and 10b (contact holes 7a and 7b) are formed at the ends of the Poly-Si 6 in the wiring direction via a SiO ₂ film 5 as an interlayer insulating film.
Are formed.

Poly-Si6 as a resistor will be described in detail later, but has a thickness of 150 nm, and BF ₂ ⁺ is ion-implanted to obtain a predetermined resistance value.

Although not shown, the resistor according to the present embodiment is preferably formed in a MOS Tr or the like.

FIG. 2 is a sectional view of the first half step of the embodiment shown in FIG.

As shown in FIG. 2A, polysilicon (Poly-Si) is deposited to a thickness of 150 nm on the LOCOS oxide film 1 by the CVD (Chemical Vapor Deposition) method along the normal process flow. Then, the Poly-Si film 2 is formed. The Poly-Si2 film is a film for forming a Poly-Si resistor.

After forming the Poly-Si film 2, as shown in FIG.
As shown in (b), boron fluoride ion (BF ₂ ⁺ ) is added by a normal ion implantation (II) technique in a concentration corresponding to a desired resistivity, for example, a dose amount of 1 × 10 ¹⁴ to
Implantation is performed on the entire surface with an implantation energy of 5 × 10 ¹⁶ / cm ^{2 of} 30 KeV. At this time, although not shown, a high concentration is injected into the electrode extraction portion using a resist mask.

Next, as shown in FIG. 2 (c), silicon ions (Si ⁺ ) were added at a dose of 5 × 10 ¹⁴ / cm ² and an implantation energy under the low temperature condition of −200 ° C. by using the low temperature ion implantation method. Implant all over at 70 KeV. By this low-temperature ion implantation, the Poly-Si film 2 becomes almost amorphous and an amorphous silicon (a-Si) film 2a is formed.

Next, the a-Si film 2a is cut into a predetermined pattern by photolithography and RIE etching, and as shown in FIG. 3A, the a-Si film pattern 2 is formed.
b is formed. After that, silicon dioxide (SiO ₂ ) is deposited on the entire surface as an interlayer insulating film by the CVD method in the range of 300 to 400.
The SiO ₂ film 5 is deposited to a thickness of nm, and then another element (for example, a MOS transistor) is formed by a normal process flow although not shown. Then 6
Anneal at a temperature of about 00 ℃ (Furnace Anneal, lamp
Anneal or laser anneal, etc.)
Re-crystallization and crystal growth of the -Si film pattern 2b are caused to change to Poly-Si6 as shown in FIG. 3 (b). This crystal growth remains due to the influence of fluorine (F) in BF ₂ ⁺ of the implanted impurity ions (dopant). In the recrystallization by this annealing treatment, the Poly-Si grain size became almost uniform. this is,
This is because, as a result of Poly-Si being made amorphous by the low temperature II, it is possible to cause crystal growth from a state in which there is no difference in crystallization.

Next, as shown in FIG. 3C, S of the insulating film is
After forming the contact holes 7a and 7b at two places of the iO ₂ film 5, Ti / TiN /
A multi-layer structure metal 10 such as Al-Si or Poly-Si / WSix (tungsten silicide) is formed, and the metal is patterned by a linography technique to form electrodes 10a and 10b as shown in FIG.

In this way, a MOS transistor having a highly accurate Poly-Si resistor having a substantially uniform grain size and a small variation was completed.

On the other hand, also for Poly-Si at the electrode take-out portion, a highly accurate and high-performance Poly-Si device can be realized by using a similar method such as low temperature II and annealing.

[0026]

As described above, according to the present invention, Bi having a polycrystalline silicon (Poly-Si) resistor having a substantially uniform grain size and a small variation in resistivity.
Semiconductor devices such as polar type, MOS type and BiCMOS type LSI can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a Poly-Si resistor according to the present invention.

FIG. 2 is a first half process sectional view of the embodiment shown in FIG.

FIG. 3 is a sectional view of a second half process of the embodiment shown in FIG.

[Explanation of symbols]

1 LOCOS oxide film (SiO _{2) 2} Poly-Si film 2a amorphous silicon (a-Si) film 2b a-Si film pattern 5 SiO ₂ film 6 Poly-Si 7a, 7b contact hole 10 multilayer metal 10a, 10b electrode

Claims (2)

[Claims] 1. A semiconductor device having a resistor made of polycrystalline silicon, wherein the grain size of the polycrystalline silicon is made uniform,
A semiconductor device characterized by reducing fluctuations in resistivity. 2. A method of manufacturing a semiconductor device having a resistor made of polycrystalline silicon, the step of forming a polycrystalline silicon film on an insulating substrate, and the step of implanting a predetermined amount of impurity ions into the polycrystalline silicon film. Next, a step of ion-implanting silicon at a low temperature of −50 ° C. or lower to change the polycrystalline silicon film into an amorphous silicon film, and after patterning the amorphous silicon film into a predetermined shape, an interlayer insulating film is formed on the entire surface. And a step of heat-treating to recrystallize the amorphous silicon film to convert it into polycrystalline silicon.