JPS59186358A - Semiconductor device with built-in resistor - Google Patents

Abstract

PURPOSE:To prevent P and B impurities from entering into an Si resistor by a method wherein an Si oxide film and a poly Si resistor are isolated by an Si nitride film. CONSTITUTION:A circuit element 12 is formed by selectively performing a double diffusion of a P type base region 13 and an N<+> type emitter region 14 on an Si semiconductor substrate 11. An Si oxide film 15 which will be formed by performing a heat treatment such as a diffusion and the like is covered on the surface of the substrate 11, an Si nitride film is adhered on the film 15 by performing a CVD method, and a poly Si layer is adhered thereon. At this time, said poly Si layer is etched into the desired shape and a resistor 17 is formed. An electrode 18 is formed by vapor-depositing Al, an ohmic contact is obtained through the intermediaries of the contact holes of the base and emitter regions 13 and 14, it is connected to the end part of the resistor by extending it on an Si nitride film 11. As a result, the film 15 and the resistor 17 are isolated by the film 16, thereby enabling to prevent the P and B impurities contained in the film 15 from entering into the resistor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to improvements in semiconductor devices with built-in resistors, particularly semiconductor devices with built-in polysilicon resistors.

(B) Prior art As shown in Figure 1, a conventional semiconductor device with a built-in resistor has an N-type semiconductor substrate (1) and a P-type base region (2) formed by double diffusion on the surface of the substrate (1). and N type emitter region (
3) and a silicon oxide film (4) covering the surface of the substrate (1).
), a resistor (5) consisting of a polysilicon layer deposited on a silicon oxide film (4), and electrodes (of vapor-deposited aluminum) connecting the resistor (5) and the regions (2) and (3).
6).

Such a semiconductor device does not rely on PN junction separation, compared to a structure in which a diffused resistor is formed in the semiconductor substrate (1).

It has the advantage that a stable resistor with few parasitic effects can be formed arbitrarily.

However, the underlying silicon oxide film (4) contains phosphorus and boron due to impurity diffusion, which enters the polysilicon layer during heat treatment during the manufacture of transistors and ICs.
Generates resistance value fluctuations.

(c) Object of the Invention The present invention has been made in view of the above, and an object of the present invention is to provide a semiconductor device with a built-in resistor that eliminates the conventional drawbacks.

B) Structure of the Invention The semiconductor device with a built-in resistor according to the present invention, as shown in FIG.
6), a silicon oxide film 00 covering the surface of the substrate α, and a silicon nitride film θ covering the silicon oxide film (G).
→, a resistor Q7 made of borin silicon provided on a silicon nitride film αQ, and an electrode θ which connects the resistor θ and the circuit element θ■.

Using an N-type silicon semiconductor substrate as (-+→ Example semiconductor substrate OI), a P-type base region 03 is formed on the substrate (11) by selective diffusion.
and N type emitter region 04) are double diffused to form a circuit element (2). Note that the circuit element (6) may be an integrated circuit other than the above-mentioned transistor. The surface (of the substrate) is covered with a silicon oxide film q formed by heat treatment such as diffusion, and this silicon oxide film q contains impurities such as phosphorus and boron. / Silicon oxide film (L) A silicon nitride film OQ with a thickness of about 80 OA is deposited on it by the CVD method, and a silicon nitride film OQ with a thickness of about 400 OA is deposited on it by the CVD method.
Deposit a thick polysilicon layer. The polysilicon layer is doped with impurities, or is doped with impurities by ion implantation later. Specifically, the specific resistance is 200
The doping amount is set to be in the range of ~IKΩ.

The polysilicon layer is etched into a desired resistor shape to form a resistor θη. The electrode (G) is formed by vapor deposition of aluminum, and the base and emitter regions (1■ α4)
The upper contact is connected to the end of the resistor θ'7 by making ohmic contact through the hole and extending over the silicon nitride film a#5.

According to the above structure, the silicon oxide film oO and the polysilicon resistor (17) are separated by the silicon nitride film αG. There is no danger of it entering the body's alpha power.

(f) Effects According to the present invention, the resistance value of the polysilicon resistor α71 can be completely prevented from changing due to impurities, and a stable resistance value can be obtained. This is particularly effective in the case of high resistance because the amount of impurity doped is small.

Furthermore, since the surface of the substrate (b) is coated with the silicon nitride film ◇Q, it is possible to stabilize the circuit element (6) incorporated in the substrate (b).

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a conventional example, and FIG. 2 is a sectional view illustrating the present invention. Explanation of main figure numbers α: semiconductor substrate, (6): circuit element, (IF9: silicon oxide film, αQ: silicon nitride film, α: polysilicon layer resistor, (to): electrode. Figure 1 Figure 2

Claims (1)

[Claims] (]) - A conductive type semiconductor substrate, a circuit element formed on the substrate, a silicon oxide film covering the surface of the substrate, a silicon nitride film provided on the silicon oxide film, and a silicon nitride film provided on the silicon nitride film. 1. A semiconductor device with a built-in resistor, comprising a polysilicon resistor and an electrode connecting the resistor and the circuit element.