JPS6377143A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To accurately obtain a high resistor by using a polycrystalline Si film for the resistor when many resistance elements are formed for an IC, implanting one conductivity type impurity ions, then implanting inert gas ions, and then not executing a heat treatment as it is. CONSTITUTION:The surface of an Si substrate 1 is covered with an SiO2 film 4, a recess is formed to match a desired resistor size, and a high purity polycrystalline Si film 3 is grown therein. Then, the film 3 is covered with an Si3N4 film 6, B<+> ions are implanted to the film 3, then heat treated at 1000 deg.C for 30 min to exchange the ions with Si atoms of crystal lattice point to be activated. Thereafter, this sheet resistor is measured, Ar<-> ions are implanted with reference to it. At this time, an accelerating voltage is set to 80% or less at the time of an impurity doping, the state that the crystal lattice remains broken by the Ar<-> ions remains without annealing, and used as a resistor. Thus, the irregularity of the resistance value is reduced to several %.

Description

[Detailed Description of the Invention] [Summary] Impurity ions of one conductivity type are implanted into a polycrystalline silicon film to be used as a resistor, heat treated, and then inert gas ions such as nitrogen (N2) and oxygen (02) are implanted. , argon (Ar)
Injecting inert gas ions such as, etc., and leaving it unheated. This method of forming a resistor allows the resistance value to be formed with higher accuracy.

[Industrial Field of Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to an improvement in a method for forming a resistor.

In semiconductor devices such as XC and LSI, many resistors (resistance elements) are incorporated into many transistor elements to form an integrated circuit. Therefore, in order to improve the quality of semiconductor devices, it is necessary to It is desired to form a resistor having a highly accurate resistance value.

[Prior Art] Conventionally, a method for forming a resistor is known in which a resistor layer is formed at the same time as a base region is formed within a semiconductor substrate, but there are hundreds of methods for forming a resistor within a substrate. Recently, it has become difficult to form a resistor with a high resistance value on the order of Ω, and a manufacturing method based on self-alignment using polycrystalline silicon has come to be adopted. A method is used in which a polycrystalline silicon film is deposited on a substrate with an insulating film interposed therebetween as a resistor layer.

FIG. 3 shows a cross-sectional view of the resistor made of the polycrystalline silicon film, where 1 is a silicon substrate and 2 is a silicon oxide (Si) insulating film interposed between the silicon substrate and the resistor.
02) Membrane, 3 is resistor, 4 is 5i02 surrounding the resistor
5 is an electrode.

Fig. 4f8) to (C1 are process diagrams showing the formation method. First, as shown in Fig. 4(a), the surface of the silicon substrate 1 is thermally oxidized to generate the 5i02 film 2, and then the 5i02 film 2 is formed. A high-purity polycrystalline silicon film 3 (eg, 5,000 to 6,000 thick) is grown thereon by vapor phase epitaxy (CVD).

Next, as shown in the same figure (bl), silicon nitride (Si
2N3) Si3N4 film 6 (film thickness of about 1000 layers) was deposited by CVD method and patterned by photo process to cover only the polycrystalline silicon film portion of the resistor region.
A film 6 is formed, and using this as a mask, the exposed polycrystalline silicon film is thermally oxidized to produce a 5f02 film 4.

Next, as shown in FIG. 4(C), boron or arsenic ions are implanted from above the Si3N4 film 6 mask, and further heat treatment is performed at a high temperature (approximately 1000 DEG C.). This heat treatment is for replacing implanted ions with silicon in the crystal lattice, arranging boron or arsenic at crystal lattice points, and activating it. After that, the Si3N4 film 6 is removed, an electrode is formed, and the third
Complete as shown in the diagram.

[Problems to be Solved by the Invention] By the way, in the above formation process, boron or arsenic ions are implanted to make the high purity polycrystalline silicon film p-type.
Alternatively, the purpose of making it n-type is to adjust the sheet resistance of the polycrystalline silicon film so that the resistor has a desired resistance value. This is because, as is well known, the resistance value of a resistor is determined by its length, cross-sectional area, and sheet resistance.

However, it is extremely difficult to obtain a highly accurate resistance value by implanting impurity ions and adjusting the sheet resistance.
The reproducibility is also not good. In particular, it is difficult to accurately form a high sheet resistance by reducing the amount of impurity implanted. This is because the lower the impurity concentration, the greater the variation.

The present invention proposes a method of forming a resistor having a highly accurate resistance value by alleviating these problems and controlling the sheet resistance with more precision.

[Means for solving the problem] The purpose is to implant impurity ions of one conductivity type into a polycrystalline silicon film provided on an insulating film, heat-treat the film, then implant inert gas ions, and then heat-treat the polycrystalline silicon film provided on the insulating film. This can be achieved by a method of forming the polycrystalline silicon film into a resistor as it is.

[Operation] That is, in the present invention, impurity ions of one conductivity type are first implanted and heat treated, and then nitrogen (N2) is implanted.

Inert gas ions such as oxygen (02) and argon (Ar) are implanted to form a resistor without heat treatment. Then, the second injection is used to adjust the sheet resistance according to the first injection. In this way, the resistance value can be controlled with greater precision.

[Example〕 Hereinafter, embodiments will be described in detail with reference to the drawings.

Figure 1 (al, (bl) shows the process order diagram of the forming method according to the present invention, while the conventional Figure 3 (al, (b)
The steps of growing a high-purity polycrystalline silicon film 3, forming a Si3N4 film 6 mask on it, and then thermally oxidizing it to generate a 5i02 film 4 are the same and are not shown in the figure. . Next, as shown in FIG. 1(a), boron ions (p-type impurity ions) are implanted from above the resistor 3 made of a high-purity polycrystalline silicon film. At that time, the dose is set to 10''7c+J and the acceleration voltage is set to about 100 KeV. Then, next, 1000℃.

Heat treatment is performed for 30 minutes to activate the implanted ions by replacing them with silicon atoms at crystal lattice points. At that time, the sheet resistance (ρS) will be several tens of Ω to several Ω4, and the sheet resistance will be measured.

Next, as shown in Figure 1 (bl), the sheet resistance (ρs
), Ar ions are 10” to 1012/c
It is implanted at a dose of about d. At this time, the acceleration voltage is set so that the Rp of Ar is 80% or less of the Rp of the first impurity. Further, no subsequent heat treatment (annealing) is performed, and the crystal lattice is left destroyed by Ar ions. The sheet resistance of the resistor 3 formed in this way is finely controlled in proportion to the dose, as shown in the relationship chart between the sheet resistance (ρS) and the dose in FIG. ) can be formed.

Note that the reason why no heat treatment is performed after the second ion implantation is to prevent the sheet resistance, which has been carefully controlled with high precision, from changing. Therefore, when the process of forming such a resistor is combined with the process of forming a transistor element, a second ion implantation process is inserted at a process location where no subsequent heat treatment of 1000° C. or higher is performed, for example, after the emitter region formation process. There is a need. On the other hand, the first ion implantation step has no such restrictions and may be inserted as appropriate.

If the above formation method is adopted, high resistance values of several hundred ohms can be formed with high precision, and conventional variations in resistance values can be reduced to ±
What used to be 10% can now be reduced to a few percent variation.

In addition, as the inert gas ion, argon (Ar
), impurity gas ions such as nitrogen (N2) and oxygen (02) can be considered.

[Effects of the Invention] As is clear from the description of the embodiments above, according to the present invention, a high-resistance element can be formed with high precision, which greatly contributes to improving the quality of ICs.

[Brief explanation of the drawing]

1(a) and 1(b) are step-by-step diagrams of the formation method according to the present invention, FIG. 2 is a graph showing the relationship between dose and sheet resistance, and FIG. 3 is a cross-sectional view of a polycrystalline silicon resistor. Figure 4 (5) to (C)
1 is a step-by-step diagram of a conventional forming method. In the figure, (2) is a silicon substrate, 2.4 is a 5i02 film, 3 is a resistor made of a polycrystalline silicon film, and 6 is a Si3N4 film. Ar-Ay- O departure leaf; figure

Claims (1)

[Claims] Impurity ions of one conductivity type are implanted into the polycrystalline silicon film provided on the insulating film and heat treated, and then inert gas ions are implanted and the polycrystalline silicon film is formed into a resistor while left unheated. 1. A method for manufacturing a semiconductor device, comprising the steps of: