JPS6118868B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of controlling a current amplification factor in manufacturing a semiconductor device.

An example of a method for manufacturing a semiconductor device is shown in FIGS. 1 to 7 in order of steps. First, a semiconductor substrate 1 is doped with base region impurities by CVD (Chemical
Vapor Deposition) film 2 is deposited (Fig. 1).
Next, heat treatment is performed to form the base region 21 (FIG. 2). Then, emitter pattern openings 2a are formed in the oxide film on the main surface (FIG. 3), and a type of impurity different from that of the CVD film 2 is formed. Doped CVD film 3
(Figure 4). Next, a heat treatment is performed to form an emitter region 31 (FIG. 5). At this time, the diffusion time is changed to control h _FE to a predetermined value. However, in a semiconductor device with a PNP structure, the base region N-type impurity diffusion and hFE
It can also be controlled. Next, a film 4 for stabilizing the surface of the insulating film is applied (Fig. 6), heat treatment is performed, and holes for leading out each electrode of the base and emitter are formed, and then an electrode material is deposited and the base electrode is formed. 22, an emitter electrode 32 is formed to form a semiconductor device (FIG. 7).

In the manufacture of semiconductor devices such as those described above, although the current amplification factor is kept within a predetermined control range during the formation of the emitter region and the heat treatment conditions after this process are exactly the same, the electrical characteristics are measured before the semiconductor substrate is pelletized. As a result, the current amplification factor _hFE varies greatly. For this reason, a product with the desired h _FE cannot be obtained, resulting in a decrease in yield.

The present invention provides an improved method for manufacturing a semiconductor device in order to eliminate the above-mentioned conventional drawbacks.

The method of manufacturing a semiconductor device of the present invention measures the base sheet resistance value after forming the base region and before forming the emitter region, sets the current amplification factor based on this measured value, and controls the emitter diffusion time to form the emitter region. It is characterized by this.

An embodiment of the present invention will be described in detail below. The outline of the manufacturing process has already been explained with reference to Figures 1 to 7, and as shown in Figure 5, after forming the emitter region, high temperature treatment and electrode metal annealing are performed to stabilize the characteristics. Depending on the process, the h _FE at the time of emitter formation varies. An example of this state is shown in FIG. That is, PNP
Structure of transistors with respective base sheet resistance ρ
205Ω/cm, 230Ω/cm, 270Ω/cm depending on _S distribution
They are divided into three types and are hereinafter referred to as #1, #2, and #3, respectively. When the emitter I _B (assuming I _C = 50 mA) is measured with emitter regions formed in each of the above, no difference is observed between #1, #2, and #3, as shown in Figure 9a. . In other words, it can be said that the values are almost the same. After high temperature treatment for stabilizing the characteristics and annealing treatment of the electrode metal, the emitter I _B (I _C =100 mA) has a distribution as shown in FIG. 9b. The above is basically due to a shift in the base sheet resistance ρ _S and I _B due to the process, and a more precise investigation revealed that the base sheet resistance ρ _S is high between #1, #2, and #3 as shown in Figure 10. It became clear that the larger the process shift, the greater the process shift. If it becomes as shown in Fig. 9b, the required range of h _FE is relative to “θ” shown in the figure.
#1 shows a large difference: 60%, #2 33%, and #3 0%.

From the above, it is concluded that h _FE should be controlled in accordance with the base ρ _S in order to keep the final h _FE constant. This method has the remarkable advantage that a semiconductor device having a desired h _FE can be obtained.

[Brief explanation of the drawing]

Figures 1 to 7 are cross-sectional views showing the manufacturing method of a semiconductor device in the order of steps, Figure 8 is a diagram showing the distribution of the base ρ _S of the wafer, and Figures 9 a and b are diagrams showing the I _B of the semiconductor element. FIG. 10 is a diagram showing the correlation between the base ρ _S and h _FE . Note that the same reference numerals in the figures indicate the same or corresponding parts, respectively. 21...Base region, 22...Base electrode, 3
1... Emitter region, 32... Emitter electrode, ρ
_S ...Base sheet resistance value, _hFE ...Current amplification factor.

Claims (1)

[Claims] 1. In manufacturing semiconductor devices, the base sheet resistance value is measured after the base region is formed and before the emitter region is formed, and the emitter region is formed by setting the current amplification factor based on this measurement value and controlling the emitter diffusion time. A method for manufacturing a featured semiconductor device.