JPS61116833A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a mask just suitable for high concentration ion implantation by laminating metal films having sufficient ion implantation rejecting performance on unexposed positive photo resist. CONSTITUTION:An oxide separation film 102, a gate oxide film 103, an Mo gate electrode 104 are provided on an Si substrate and the surface is then rotatably coated with a positive photoresist 105 and is then baked. Next, Mo 106 is deposited under the condition that the resist 105 is not sensed in such a thickness that implanted ion almost stays within the Mo film. Next, with the positive photo resist 107 used as the mask, Mo is easily etched using reduced H2O2 solution without giving any influence on the base resist 105. Any damage is not given to Mo 104 even after the exposure and development. After forming high concentration ion implantation layer 108, the resist 105 is removed by dissolving it and then Mo is lifted off. The resist 105 is covered with Mo and it does not change in property and can easily be exfoliated with an ordinary organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a high concentration ion implantation mask.

[Conventional technology]

Ion implantation is becoming a mainstream method for introducing impurities in semiconductor device manufacturing processes, replacing the conventional thermal diffusion method. A typical example is when it is used to form a highly concentrated impurity layer such as a source or drain electrode of an MO8 field effect transistor (hereinafter abbreviated as MOSFET), which is a basic element constituting a VLSI. Among them, the range of use has been rapidly expanding recently due to its low power consumption characteristics.

Complementary amount MO8 (hereinafter abbreviated as 0MO8) When using ion implantation to form the source and drain of an FET, two types of impurities with different conductivity types are separately implanted for two types of MOSFETs, N-channel type and P-channel type. The need arises. This means that an implantation mask is required to distinguish between N-channel and P-channel when performing two high-concentration ion implantations.

The simplest way to use a mask for ion implantation is to use a photoresist film with openings formed at the positions where ions are to be implanted. However, for long MOSFET source/drain formation, at least 1015 ions/C
A high dose of approximately m2 or more is usually required, and in such cases, light hydrogen atoms, etc., are ejected from the photoresist surface layer due to excessive ion bombardment, and heavy atoms, such as carbon atoms and implanted atoms, are An altered layer that is thought to remain is formed. Unlike a photoresist film that has undergone a normal exposure and development process, such a photoresist film cannot be removed at all by a method using a common organic solvent. Currently, boiling treatment in a strong acid, long-term oxygen plasma treatment, or a combination thereof is generally used to peel off a photoresist film that has deteriorated in quality. These peeling methods have relatively few problems when conventional polycrystalline silicon is used as dart electrodes (problems to be solved by the invention). If high-melting point metals are introduced as f-) electrode materials in accordance with the trend of That is, when boiling in a strong acid, there is a possibility that the high melting point metal will be deformed, altered, or dissolved. In addition, in the oxygen plasma treatment, there is a possibility that the high melting point metal is oxidized, which may cause damage that affects the MOS ratio.

The purpose of the present invention is to meet the characteristics required for a mask for high-concentration ion implantation, that is, to be easy to form and peel off, not to damage the base film (particularly metal film) during peeling, and to have sufficient implantation blocking ability during implantation. An object of the present invention is to provide a method for manufacturing a high concentration ion implantation mask having the following steps.

[Means for solving problems]

The present invention involves a step of applying a bottom-type photoresist film on the surface of a semiconductor substrate, and a metal film having a thickness that hardly allows ions to penetrate under ion implantation conditions that are performed later on the resist film in an atmosphere where the resist film is not exposed to light. (a step of depositing the metal film, a step of removing an arbitrary region of the metal film by a photoresist step and a metal film etching step, and an exposure/development step using the metal film as a mask) This method of manufacturing a semiconductor device is characterized by performing a step of selectively removing a region below a region removed by etching.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the present invention in the order of steps. In the jg1 diagram (&), silicon substrate 1
After forming a thick silicon oxide film 102 for isolation between elements on 01, a dirt insulating film 103 is deposited, and a high melting point metal film 104 such as molybdenum, which will become a gate electrode, is formed, and then a positive photorenost film 105 is formed. After spin coating and baking to remove the solvent, a metal film 106 of molybdenum, titanium, etc. is deposited under vapor deposition conditions that do not expose the positive photoresist film to light.
The thickness of the metal film varies depending on the acceleration voltage and dose of high-concentration ion implantation, and is selected so that most of the implanted ions remain within the metal film. Further, as for the vapor deposition method, if the positive type photoresist film is not exposed to light, it will not be possible to use any of the vapor deposition methods, such as the starburst method, the electron beam method, and the resistance heating method. Next, in Figure 1 (b), a second photorenost film 107 is applied, and an opening is formed in the region where high concentration ions will be implanted later. etching. Metal etching can be easily carried out using cold hydrogen oxide based etching for molybdenum and dilute hydrofluoric acid for titanium without affecting the underlying positive photoresist at all. Figure 1 (,) shows the metal film 1 after the entire surface was subjected to Fuji development.
This figure shows the state in which the bottom-shaped photoresist film 105 under the opening 06 has been removed. At this time, the second photoresist) M 10
If 7 is selected as the ysy type, the second photorenost film 107 remaining on the metal J[106 is also removed at the same time. This process is a normal exposure and development process and does not cause any damage to the underlying high melting point metal 104. In FIG. 1(d), the highly concentrated impurity layer 108 is removed by ion implantation to form source and drain electrodes. Since the positive type photoresist film is covered with a metal film and is implanted with high concentration ions, it does not change in quality at all and can be easily peeled off with a general organic solvent.

〔Effect of the invention〕

As is clear from the description of the examples above, in the present invention, a metal film having sufficient ion implantation blocking ability is layered on unexposed positive photoresist and this is used as an implantation mask, so it is different from the case of a single layer of photoresist. It is possible to avoid the problem of resist peeling caused by deterioration of the photoresist layer due to ion bombardment during high-concentration ion implantation. In addition, the process of forming a pattern on the injection mask having a two-layer structure can be carried out using normal exposure, development, and rennost peeling processes using an organic solvent, and can be performed without any adverse effect on the properties of the underlying metal film, etc. I can do it.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are cross-sectional views showing the manufacturing process according to the present invention in order of process. 101...Silicon substrate, 102...Silicon oxide film, 103...r-) insulating film, 104...Dart metal, 105...Taposi type photoresist, 106...
...Metal film, 107...Photoresist, 108...
impurity layer. Figure 1

Claims (1)

[Claims] (1) The step of coating a positive photoresist film on the surface of a semiconductor substrate, and the subsequent ion implantation on the resist film in an atmosphere where the resist film is not exposed to light, are coated with a metal film having a thickness that hardly allows ions to penetrate. a step of removing an arbitrary region of the metal film by a photoresist process and a metal film etching process; and a process of etching and removing the metal film of the positive photoresist film by an exposure and development process using the metal film as a mask. 1. A method for manufacturing a semiconductor device, comprising: selectively removing a portion under the removed region.