JPH03187255A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To enable formation of a poly-Si resistor with high reproducibility by thermally activating the poly-Si resistor in the final heat treatment stage of fabrication process. CONSTITUTION:An oxide film 51 is removed from parts for forming emitter, base and collector, arsenic is implanted with only the base region 6 is masked with resist thus forming emitter and collector electrodes. Platinum is then deposited and heat treatment for silification is carried out, yet reacting platinum is removed and an oxide film 52 is deposited followed by deposition of poly-Si film 81, and then p or n-type ions 12 are implanted onto the entire surface. Thereafter, high temperature, short time annealing is carried out by means of a lamp or a diffusion furnace as the final high temperature heat treatment for activating impurities. By such method, variation or dispersion of the resis tance of poly-Si can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing semiconductors such as bipolar devices and MO8 type devices that utilize polysilicon as a resistor.

[Conventional technology]

In general, in the manufacturing process of semiconductor devices, polysilicon is used not only for the base and emitter extraction electrodes of bipolar transistors or the gate electrodes of MOS transistors, but also as resistive elements in integrated circuits. This will be explained with reference to FIG.

Figures 2 (,) to (d) are process cross-sectional views schematically showing the manufacturing process of this conventional bipolar device. A case is shown in which the same polysilicon used for the electrode is used as a resistor.

In FIG. 2, 1 is a p-type S1 substrate, 2 is an n+ buried diffusion layer, 3 is an n epitaxial layer, 4 is a collector all, and 5°5! and 5! is an oxide film, 6 is a p base region, 7 is an oxide film,
is an n+ emitter region, 8 is polysilicon, 9 is a silicided region, and 10 is an aluminum (At) wiring υ, and the process is roughly l! is described below.

That is, when manufacturing a bipolar device using polysilicon for a pace extraction electrode as a resistor, as shown in FIG. After removing the oxide film, a polysilicon film 8 is formed. After boron is injected into the entire surface, a resist 11 having a predetermined pattern is formed by photolithography. Then,
As shown in FIG. 2(b), the polysilicon film 8 is selectively etched using the resist 11 as a mask, and the polysilicon film 8 for the base extraction electrode is patterned.
1& and polysilicon resistor 8b, a CVD oxide film 5! Deposit. Next, as shown in FIG. 2C, after the emitter 7 is diffused, the oxide film on the contact forming part of the bipolar transistor 21 and the contact part of the polysilicon resistor part 8b is removed, and then platinum is deposited by sputtering. After the platinum is deposited as silicide by heat treatment at 600° C. for 20 minutes in N snow, unreacted platinum is removed by aqua regia. Then, as shown in FIG. 2(d), CV
After depositing the D oxide film 52, a hole is opened at the contact portion with the aluminum wiring 10 and the patterning of the aluminum wiring 10 is completed, thereby producing a bipolar device having the structure shown in FIG. 4(d).

That is, as shown in FIG. 2, the polysilicon film 8 is configured to function as a base lead electrode 8a in the bipolar transistor section 21 and as a polysilicon resistor 8b formed on the thick oxide film 5. In this case, even if the polysilicon resistor 8b is of the same p-type as the base electrode, or even if the polysilicon resistor 8b is of the same p-type but has a different amount of boron injection than the base electrode, it can be distinguished by whether one mask is required or not. . Similarly, even if the polysilicon resistor 8b is an n-type impurity, it is possible to use one mask.

What is characteristic here is that the polysilicon film is formed in the same film as the base extraction electrode. Therefore, in this example, the portion 8b that becomes the polysilicon resistor will be subjected to emitter impurity diffusion and activation heat treatment at least once at 800°C or higher, which will cause crystal grain growth of the polysilicon film. It turns out. Generally, grain growth reduces scattering of electrons at grain boundaries, resulting in lower resistance.

In addition, a transistor with a polysilicon emitter extraction electrode or MO8fi with a polysilicon gate structure)
Similarly to the above, in transistors, when polysilicon forming the emitter lead electrode or gate electrode is also used as a resistor, the same activation heat treatment as above is applied to prevent crystal grain growth and eventually fluctuations in resistance value. happen.

[Problem to be solved by the invention]

In this way, in the conventional method, polysilicon for the base electrode or polysilicon for the emitter electrode is used for bipolar devices, and polysilicon for the gate electrode of the casing is made of the same polysilicon, regardless of whether it is p-type or n-type polysilicon. When resistors made of silicon are subjected to high-temperature activation heat treatment later, crystal grains of polysilicon grow, causing fluctuations in resistance. Therefore, there is a problem in that the manner of change changes in a complicated manner depending on temperature changes, the number of times of heat treatment, etc.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can form a polysilicon resistor with good reproducibility.

[Means to solve the problem]

In the method for manufacturing a semiconductor device according to the present invention, the polysilicon resistor is formed after the formation of the transistor part is completed, and the polysilicon resistor is activated by lamp annealing at high temperature and in a short time, or By diffusion furnace, i5
A final high temperature heat treatment of 900° C. or higher is performed.

[Effect]

In the present invention, by performing the heat treatment for activating impurities in the polysilicon resistance as the final high-temperature heat treatment, changes and variations in the polysilicon resistance can be suppressed.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic process cross-sectional view showing an embodiment of the method for manufacturing a semiconductor device according to the present invention. In this figure, the same or corresponding parts as in FIG. 2 are given the same reference numerals.

First, as shown in FIG. 1 (1), after completing the formation of the collector and base junctions of the bipolar transistor 21 as in the conventional example, after removing the oxide film on the active region,
After depositing a polysilicon film and implanting boron into its entire surface, the polysilicon film 8a is left only in a predetermined region, that is, in the lead-out portion of the base electrode, and then a CVD oxide film 5I is deposited.

Next, as shown in FIG. 1(b), after removing the oxide film on the parts that will become the emitter, base, and collector electrodes, arsenic is implanted while only the base region is covered with resist to form the emitter and collector electrodes. do. Then, platinum is deposited by sputtering, heat treatment is performed for silicidation at 600° C. for 20 minutes in N2, and unreacted platinum is removed by aqua regia, and then a CVD oxide film 52 is deposited. A polysilicon film 81 is deposited, and then KP type or n type ion implantation 12 is performed on the entire surface. Thereafter, final high-temperature heat treatment for impurity activation is performed by lamp annealing, annealing in N2 at 1000° C. for 30 seconds, or annealing at 900° C. for 30 minutes in a diffusion furnace.

Next, as shown in FIG. 2(c), the resist 11 is formed into a predetermined dimension by photolithography! form.

Next, as shown in FIG. 2(d), after etching the polysilicon lN8s using the patterned resist 11t as a mask, a CVD oxide film 53 is deposited, a resist 1h is formed, and the transistor 21 and polysilicon 1N8s are etched. Photolithography is performed on the contact portion of the resistor portion 8b.

Next, as shown in FIG. 2(), after forming the polysilicon film 8a for the base extraction electrode, a new polysilicon resistor is formed to complete the patterning of the aluminum wiring 10 after forming the contact hole. A bipolar device formed with 8b is created.

As described above, according to the method of the above embodiment, after the emitter diffusion, which normally requires heat treatment at 900° C. or higher for about 30 minutes in a diffusion furnace, the polysilicon film 1b serving as a resistor is deposited and the impurities are activated. By patterning, extra heat treatment that causes changes in crystal grains can be avoided as much as possible, so the reproducibility of polysilicon resistance can be dramatically improved.

In the above embodiment, the case of a bipolar transistor was described in which the polysilicon film of the polysilicon resistor 8b was formed after the formation of the polysilicon resistor 8b for the base extraction electrode. The silicon film is the same polysilicon film as the polysilicon film for the emitter electrode, or after the polysilicon film for the emitter electrode is formed.
Even if a newly formed polysilicon film is used, the same effect as in the above embodiment can be obtained. ! (Polysilicon resistor)
Similarly, for MOS) transistors, a new polysilicon film is formed in the process after the source and drain activation heat treatment, unlike the polysilicon for the gate electrode.
Of course, the present invention can also be applied to resistors for the same reason.

〔Effect of the invention〕

As described above, according to the present invention, the activation heat treatment of the polysilicon film for resistor formation is the final heat treatment at 900° C. or higher in the manufacturing process, and the subsequent 800° C.
By minimizing the additional heat treatment by CVD at about 0° C., it is possible to suppress the growth of polysilicon crystal grains. This makes it possible to suppress changes and variations in polysilicon resistance and to create polysilicon resistors with good reproducibility.

[Brief explanation of drawings]

Figures 1 (1) to (,) are cross-sectional views showing the manufacturing process of a bipolar device according to an embodiment of the present invention;
d) is a cross-sectional view showing the manufacturing process of a bipolar device by a conventional method. 1...p-type Si substrate, 2...n buried diffusion layer, 3...n'''' epitaxial layer...collector all, 5, 5+, 5z, 5s...oxidation Film, 6...Base region, 7...Emitter region, 8.8+...Polysilicon film, 8a...
Polysilicon for base extraction electrode 4.8b... Polysilicon resistor, 9... Silicided region, 10...
...Aluminum wiring, 11, 111. I Is...
-Resist, 12...Ion implantation, 21...Bipolar transistor. Figure 1 (a) 1 Figure (d)

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device, the semiconductor device having polysilicon as a resistor, wherein the final heat treatment in the manufacturing process is heat treatment for activating the polysilicon resistor.