JPS61285715A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To restrain the charge-up phenomenon, by forming previously the metal conductor thin film layer on the photoresist film for forming the source and the drain regions, and implanting ions from above this metal conductor thin film layer. CONSTITUTION:The metal conductor thin film layer 8 of tungsten and aluminum, etc. is formed previously on the photoresist film 4 to be used as the implantation mask. The source region 6 and the drain region 7 are selectively formed by the ion implantation 5 from above this metal conductor thin film layer 8. The electric charges of implanted positive ions are effectively neutralized by the secondary electrons emitted from the metal conductor thin film layer. Therefore, the charge-up of electric charge on the thin oxide film of the gate part of the silicon semiconductor substrate can be restrained, and the electrostatic breakdown, etc. can be satisfactorily prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for manufacturing a semiconductor device, and in particular, a method for manufacturing a semiconductor device that prevents charge-up and electrostatic damage to a substrate that occurs during an ion implantation process. This is related to.

[Conventional technology]

Source in conventional semiconductor device manufacturing methods.

FIG. 2 shows a cross section of the polysilicon gate structure MO3-IC at the time of forming the drain impurity region.

That is, as is clear from this Figure 2, in
Field oxidation M is formed on the main surface of the silicon semiconductor substrate 1.
A gate portion consisting of thin oxide 113a and polysilicon layer 3b is formed between 2 and 2, and photoresist film 4 is patterned on top of these.In the conventional method, photoresist 11!4 is formed in this state. The source region e and the drain region 7 are selectively formed by ion implantation 5 using the mask as a mask.

[Problem that the invention seeks to solve]

However, in the conventional method of manufacturing N0J-IC with a polysilicon gate structure.

During the process of forming source and drain impurity regions, the ion implantation causes the top surface of the substrate to be charged up, causing electrostatic damage to the thin oxide film 3a of the gate formed between the source and drain. There was a problem.

This charge-up phenomenon on the upper surface of the silicon semiconductor substrate is caused by the fact that the ions implanted when forming the source and drain regions are positive ions (for example, 11a'', 75AS).
''), this charge is applied to each insulating thin film formed on the upper surface of the substrate, that is, for example, an oxide film, a polysilicon layer, and a photoresist layer.

Therefore, an object of the present invention is to suppress the charge-up phenomenon on the upper surface of the substrate that accompanies ion implantation during the impurity region forming process, and in particular, in view of the problems with the conventional method. An object of the present invention is to provide a method for manufacturing a semiconductor device that can prevent electrostatic damage to a thin oxide film formed in a gate portion.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes forming a metal conductor thin film layer in advance on a photoresist film serving as an implant mask for forming source and drain regions, and Ions are implanted from above to form source and drain regions.

[For production]

Therefore, in the method of the present invention, in order to perform ion implantation after forming a metal conductor thin film layer in advance on a photoresist film as an implantation mask, secondary electrons from this metal conductor thin film layer are removed during ion implantation. The discharge effectively neutralizes the charge of the implanted positive ions, thereby suppressing the build-up of charges on the upper surface of the substrate.

〔Example〕

Hereinafter, one embodiment of the method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to FIG.

This embodiment method in FIG. 1 is a cross-sectional view of an IOS-IC (with a polysilicon gate structure) during the step of forming source and drain impurity regions, which is shown in correspondence with the conventional method in FIG. 2. In each of these figures, the same reference numerals indicate the same or corresponding parts. In this embodiment method, a metal conductor thin film layer 8 of tungsten, aluminum, etc. is formed, and ion implantation 5 is performed from above this metal conductor thin film layer 8 to selectively form the intended source region 8 and drain region 7.

Therefore, in the case of this embodiment method, when the positive ions implanted for forming the source and drain regions 8 and 7 collide with the metal conductor thin film layer 8, the metal conductor thin film layer 8 emits two ions. The secondary electron is released and the charge of the positive ion is neutralized,
The charge-up on the silicon semiconductor substrate 1 during this ion implantation can be effectively suppressed, and at the same time, by forming the metal conductor thin film layer 8 on the photoresist film 4, the oxide film and the inside of the silicon semiconductor substrate can be suppressed. It is also possible to effectively prevent metal contamination on the device.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, prior to forming the source and drain regions, a metal conductor thin film layer is formed in advance on a photoresist film serving as an implant mask, and a metal conductor thin film layer is formed on the metal conductor thin film layer. Source as if performing ion implantation.

Since a drain region is formed, the charge of implanted positive ions can be effectively neutralized by secondary electron emission from the metal conductor thin film layer, and the charge of positive ions can be effectively neutralized by secondary electron emission from the metal conductor thin film layer. It is possible to suppress charge build-up, effectively prevent electrostatic damage to the gate oxide film that occurs in conventional methods, and it is structurally relatively simple and can be implemented easily. It has the following features.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a polysilicon gate structure MO5-IC during the process of forming source and drain impurity regions, showing an embodiment of the method for manufacturing a semiconductor device according to the present invention, and FIG. Same as above polysilicon gate structure M
It is a sectional view of O9-IC. l...Silicon semiconductor substrate, 3a and 3b...
・Thin oxide film and polysilicon layer (gate part), 4.
... Photoresist film, 8... Source region, 7...
...Drain region, 8...Metal conductor thin film layer.

Claims (1)

[Claims] In manufacturing semiconductor devices with polysilicon gate structure,
A semiconductor device characterized in that a metal conductor thin film layer is formed in advance on a photoresist film serving as an implant mask for forming source and drain regions, and ions are implanted from above the metal conductor thin film layer. Production method.