JPH0528497B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a method of manufacturing a semiconductor integrated circuit using a technique of bombarding a semiconductor substrate with ions, such as ion implantation or dry etching such as reactive ion etching or plasma etching.

[Prior art and its problems]

During the ion implantation or dry etching process, when ions are bombarded with a semiconductor substrate, the ion bombardment causes lattice defects in the semiconductor crystal.
Since the surface condition deteriorates, subsequent microfabrication becomes impossible, and desired characteristics cannot be obtained from the integrated elements.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor integrated circuit in which microfabrication is performed while preventing radiation damage to a semiconductor substrate due to ion collisions by solving the above-mentioned problems.

Summary of the Invention The present invention utilizes the fact that the reverse characteristic of a diode deteriorates when damage caused by ion bombardment occurs to the semiconductor substrate constituting the diode. A monitoring diode is formed in the semiconductor substrate, and the reverse characteristics of the diode are measured. If radiation damage to the semiconductor substrate is detected due to deterioration of the reverse characteristics, damage caused by ion collision can be detected by controlling the conditions of the process using ions. To achieve the above objectives by preventing

[Embodiments of the invention]

FIG. 1 shows a monitoring diode formed in a semiconductor substrate of an integrated circuit in one embodiment of the present invention, in which an N layer 3 is present in a P well 2 provided in an N type silicon substrate 1. FIG. A P ⁺ contact layer 4 is also provided in the P well 2 in a C-shape.
The P-well 2 is, for example, a CMOS structure P-well,
N layer 3 and P ⁺ layer 4 are N channel MOS, P channel
It can be created using the same diffusion process as the source or drain region of a MOS. A cathode electrode 6 and an anode electrode 7 made of Al are in contact with the N layer 3 and the P ⁺ layer 4 at the openings of the oxide film 5, and both electrodes are connected to a cathode terminal 8 and an anode terminal 9, respectively. When manufacturing an integrated circuit, a voltage is applied between the cathode terminal 8 and the anode terminal 9 with the cathode terminal being positive, and the reverse characteristics of the monitor diode are measured. If it is determined that the radiation damage to the silicon substrate exceeds the permissible limit due to deterioration of the reverse characteristics, the integrated circuit in that manufacturing lot can be rejected without performing a functional characteristics test. From the next production lot, it is possible to prevent radiation damage from occurring by controlling the working conditions of ion implantation or dry etching, for example by reducing the ion accelerating voltage.

【Effect of the invention】

The present invention provides a monitor diode on the semiconductor substrate of an integrated circuit, and monitors radiation damage during ion implantation and dry etching processes using the diode's reverse characteristics.There is no need to prepare a separate monitor sample, and radiation damage can be monitored. If it is below the allowable limit, integrated circuits manufactured on the same semiconductor substrate can be used as products as they are, which is advantageous in terms of production control, and has an extremely large effect on the manufacture of highly reliable integrated circuits.

[Brief explanation of the drawing]

FIG. 1 shows a monitor diode in one embodiment of the present invention, in which a is a plan view with the surface oxide film removed, and b is a cross-sectional view. 1: Silicon substrate, 2: P well layer, 5: Oxide film, 6: Cathode electrode, 7: Anode electrode, 8:
Cathode terminal, 9: Anode terminal.

Claims (1)

[Claims] 1. In a method for manufacturing a semiconductor integrated circuit that includes a step of bombarding a semiconductor substrate with ions, a monitoring diode is formed on the semiconductor substrate, and the reverse characteristics of the diode are measured to detect damage to the semiconductor substrate due to ion bombardment. A method for manufacturing a semiconductor integrated circuit, characterized by: