JPS60254751A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate surface irregularity after the formation of a pattern and to prevent the breakdown of wire when an aluminum pattern is formed, by manufacturing a semiconductor in consideration of the fact that the thickness of an oxide film becomes twice when polysilicon is oxidized. CONSTITUTION:Poly Si 13 [its thickness is (t)] is formed on the entire surface of a substrate 11. The poly Si 13, which is not coated by resist 14, is etched by about 1/3 the entire thickness. Doping is not performed at a part, which requires the pattern of the poly Si 13. Only the other part is doped. Thus difference in impurity concentration is provided. When the poly Si is oxidized, the thickness of the oxide film becomes twice. The thickness of an oxide film 15 at a part, where the poly Si with a thickness of 2/3t is oxidized, becomes 4/3t. Thus the surface is flattened. Then patterning of an Al wiring 17 is performed. In this way, the breakdown of the wire can be perfectly prevented.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a method for manufacturing a semiconductor device, and is based on the fact that the oxidation rate of polysilicon is affected by the impurity concentration. ! ! The present invention relates to a method of manufacturing a semiconductor device that can eliminate I and can be planarized.

[Conventional technology]

Figure 2 shows conventional polysilicon wiring.
After forming a thin Sin film 2 on a silicon substrate 1, a polysilicon layer 3 which will become a wiring layer is formed, and a photoresist 4 is formed in the area where the polysilicon wiring is to be formed (FIG. (α)).

Next, the polysilicon layer 3 is etched using the photoresist 4 as an intermediate layer (Fig.
An oxide film 5.6 is formed on the surface. At this time, a portion 3' of the polysilicon 3 shown in the figure remains (FIG. (C)). The surface of the substrate obtained in this way has irregularities due to the formation of polysilicon wiring (part 3') (Fig. Cd).
However, there is a drawback that when a wiring 7 made of At or the like is formed, the wire breaks at the stepped portion 8.

[Problem that the invention seeks to solve]

The present invention aims to provide a method for manufacturing a semiconductor device that can eliminate unevenness after polysilicon wiring and can achieve planarization.

[Means for solving problems]

In the present invention (;), a C-nivolisilicon layer is formed on a substrate, a thick part and a thin part are formed in a predetermined pattern on this polysilicon layer, and the thin part is selectively doped with an impurity, The polysilicon layer is then oxidized, and by taking advantage of the fact that the oxidation rate of polysilicon is affected by the impurity concentration, the thinner parts of the film are converted to oxide, while the thicker parts remain as polysilicon. After the oxidation, the surface of the substrate at C2 is flattened.

[Effect]

When polysilicon is partially doped with impurities to create a difference in impurity concentration, the oxidation rate is higher in the areas with higher impurity concentrations. Therefore, even if all parts other than the pattern are oxidized, the polysilicon layer remains in the pattern part. When polysilicon is oxidized, the oxide film thickness doubles, so if this is taken into consideration when designing, the surface of the substrate after oxidation can be flattened.

〔Example〕

FIG. 1 (shows one example) As shown in FIG. is the underlying oxide film. Then, as shown in Figure 2 (A), the poly 5i15. For example, phosphorus) is doped by ion implantation.In this way, the portions of the poly-Si 13 that require a pattern are not doped, but only other portions are doped, creating a difference in impurity concentration.The amount of doping is , so that the concentration of the doped part is about 1Q am at the peak value (
= do. The dose of ion implantation is 10111i~
It will be about 1016CrrL-2.

Next, when oxidation is performed, the oxidation rate is about twice as high in areas with a high impurity concentration, so even if all areas other than the pattern are oxidized, the poly S number layer 16' remains in the pattern area (Fig. d)). The oxidation is, for example, thermal oxidation at about 1000°C. When the silicon substrate 9Si is oxidized, the oxide film thickness doubles, so the oxide film 15 in the area where the 2/3t thick poly 1si1s is oxidized is 4/3t (the oxide film 1 on the base of the polySi).
2 is not considered), on the other hand, at this time, the thickness of the pattern part is 1t.
After that, as shown in the figure (-), a contact hole 18 is formed as in the conventional method, and the At wiring 1 is oxidized.
Perform patterning in step 7. According to this embodiment, disconnection of the At pattern can be completely prevented.

Although one embodiment of the present invention has been described above, the present invention can be widely applied to the manufacture of integrated circuits using polysilicon.

〔Effect of the invention〕

According to the present invention, by utilizing the fact that the oxidation rate of polysilicon increases as the impurity concentration increases, it is possible to eliminate unevenness after forming a polysilicon pattern, and advantageously, it is possible to prevent wire breakage when forming an aluminum pattern. There is.

[Brief explanation of drawings]

FIG. 1 is a process diagram of an embodiment of the semiconductor device manufacturing method of the present invention, and FIG. 2 is a process diagram of a conventional semiconductor device manufacturing method. (Main symbols) 11... Substrate 12... Base oxide film 13... Polysilicon layer 14... Resist 15... Oxide film 17... At wiring 18... Contact hole patent application Person Fujitsu Limited Agent Patent Attorney Gobe Tamamushi (1 other person) Figure 1 Figure 2

Claims (1)

[Claims] On the substrate (form a polysilicon layer, form a thick part and a thin part in a predetermined pattern on the polysilicon layer, selectively dope impurities into the thin part, and then oxidize the polysilicon layer) By taking advantage of the fact that the oxidation rate of polysilicon is affected by the impurity concentration, we change the thin part of the film to oxide (=, the thick part is oxidized so that the polysilicon part remains). and flattening the surface of the substrate after oxidation.