JPS5866336A - Method of manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To reduce life of carriers at forming emitter region using POCl3, by a method wherein diffusion temperature and gas concentration are raised and crystal distorsion is produced at the emitter region. CONSTITUTION:Si substrate 3 is heated 1 to about 1,100 deg.C and POCl3 together with N2 and O2 (for preventing POCl3 from etching by thermal cracking gas) is flowed and emitter diffusion is performed. Flow rate of POCl3:N2:O2=1:2:1 is supplied and the treating of about 30min is performed, and P having smaller atomic radius than that of Si is forcedly injected at high concentration into the emitter and larger stress is produced and strain is produced in Si substrate and the storage time is decreased and switching property is improved. Strain state can be freely selected by controlling the temperature, gas flow rate and diffusion time. In this constitution, since conventional metal diffusion is not used the limitation for crack by contamination of SiO2 is obviated and switching property can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and particularly to an improvement in a method for manufacturing an NPN transistor which requires good switching characteristics.

Conventionally, diffusion type transistors such as mesa type and Brenna type (NPN) transistors, which require good switching characteristics, have good high frequency characteristics and are very good! Even if the transition frequency is high, the switching speed when used for switching is not necessarily high. In order to reduce the storage time (tsL) of switching characteristics, it is necessary to shorten the lifetime of carriers in semiconductors. , iron, nickel (of the above, gold is most commonly used), so-called lifetime killers, are introduced by diffusion from the collector side of the transistor.

However, with the above method, gold is also diffused into the silicon oxide film deposited on the surface, increasing the leakage current of IC110e CIO, etc., making it impossible to obtain high reliability, and due to variations in gold diffusion. The drawback is that it is difficult to precisely control storage time. In addition to the above, means for thickening one layer of the active region of a semiconductor substrate, base (P layer)
Although there are measures such as increasing the concentration of the material or narrowing the base width (Wi+), these methods are not suitable because they are limited by constraints from other required characteristics.

This invention was made to improve the drawbacks of conventional locks.It improves emitter diffusion in the manufacture of semiconductor devices that require switching characteristics, creates strain in silicon crystals, and measures lifetime values. It is characterized by the following.

The present invention will be described in detail below with respect to one embodiment. Figure 1 shows an impurity diffusion device used in a first embodiment, in which silicon substrates (3), (3'), etc. are charged into a quartz reaction vessel (2) inserted into a heating furnace (1). A reaction gas inlet (4m), (4b), etc. is provided for introducing the reaction gas from one end of the reaction container to create a predetermined atmosphere inside the reaction container, and the other end of the reaction container is It has an open end. The device on the lock heats the silicon substrate to 1050℃~
Heating to 1100°C, phosphorus oxychloride (POCIs) t carrier gas N! for emitter diffusion from the reaction gas inlet! A chlorine-based gas (PCI!i, Cjz), which is a gas produced by decomposition of phosphorus oxychloride, flows in together with a pseudo gas to prevent etching and performs emitter diffusion. At this time, for example, with the ratio of the flow rates to phosphorus oxychloride and N to 1:2:1, for 15 to 30 minutes, the source exceeding the radius of the silicon atom (smaller than the silicon atom) is forced. This causes a large stress (dislocation occurs when ps is less than 15 to 15) and causes distortion in the silicon substrate, resulting in a decrease in τ, a decrease in storage time, and a decrease in switching characteristics. will improve. , the state of strain in the nickel can be determined by controlling the temperature, gas flow rate, and diffusion time as shown in Figures 2 (a) to (d).
You can choose arbitrarily as shown. That is, each of the figures shows the strain in silicon detected by subjecting the emitter section to dilat etching, and the crystal orientation of the silicon is shown. Furthermore, Figures 1 (C) and (d) show cases where the distortion is considerably large, and the diagonal lines indicate that a dent has occurred, which is shown in black in the photograph. the above(
In order to generate the distortions shown in a) to (d), the following steps were carried out.

Figure 2 (&) Heating temperature ('C) 105G Type of atmospheric gas, flow rate (L/min), time (min)
1 -1 -1 03 05-0.5-05 POCIs O- (15-0 Time (minutes) 5-15-5 Figure 2 (B) Heating temperature (°C) 1o5° Type and flow rate of atmospheric gas (L / minute), time (9) bird
To 1 -1 -1 05- O5-05 POCIs O-05-0 Time (minutes) 5-30-5 Figure 82 (e) Heating temperature CC) 1100 Type and flow rate of atmospheric gas (L/min), hour- Between @)Nx
To 1 -1 -1 05-05-05 POCIs O-05-0 Time (min) 5-15-5 Fig. 2 (d) Heating temperature (℃) 1100 Type and flow rate of atmospheric gas (L/min), Time @)Nx
1 -1 -1 020S 05 05 POClm 6 0.5 0 Time (minutes) 5-30-5 According to the present invention, strain is generated in the silicon crystal by the emitter region shape to improve the unfitting characteristics. Since there is no diffusion of metal that shortens the lifetime as in the conventional method, there is no need to limit leakage current caused by contamination of the silicon oxide film, and there is a remarkable effect that it can be controlled arbitrarily.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an apparatus for diffusing impurities into a semiconductor substrate, and FIGS. 2 (1) to (d) are views showing strain in the emitter section. 7.1 Heating furnace 2 Reaction vessel 3.3 ' Silicon substrates 4&, 4b Reactive gas inlet agent Patent attorney Inoue Figure 1 Figure 2 (lλ (b) (C) (d,) Procedural amendment (
Voluntary) 57.1.13 Showa year, month, day, Japan Patent Office Commissioner Shima 1) Haruki Tono1, Indication of the case 1982 Patent - No. 1634222, Title of invention Method for manufacturing semiconductor device 3, Person making amendment case Relationship with Patent Applicant (307) Tokyo Shibaura Electric Co., Ltd. 4, Agent Address: 144 Kurude 4, Ota-ku, Tokyo, Item 41 @ No. 11 - Tsunoda Building Inoue Patent Dispute Office 5, Specification subject to amendment Column 6 of the Detailed Description of the Invention, page 3, line 19 (second line from the end) and line 20 (from the end) of the statement of contents of the amendment will be amended next. 1 A source that causes strain in the silicon lattice (a very highly doped heron; phosphorus atoms have a smaller atomic radius than silicon atoms) is forced to become an emitter.

Claims (1)

[Claims] In a method for manufacturing a semiconductor device including formation of an emitter region using phosphorus oxychloride as a diffusion source and a φ stage for shortening the lifetime, the diffusion temperature is adjusted so as to cause strain in the silicon crystal of the region. A method of manufacturing a semiconductor device, characterized in that formation of an emitter region and shortening of lifetime are eliminated by performing diffusion with a high gas concentration.