JPH01231348A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the flat hole-burying of a surface having small crystal grains by burying a contact hole with tungsten or molybdenum by sputtering. CONSTITUTION:A phospho-silicate glass layer 13 is formed onto an silicon substrate 14, a contact hole 11 is shaped, and tungsten is deposited onto a surface through sputtering in thickness of 0.8mum. Tungsten 12 shaped in this manner is peeled from the phospho-silicate glass layer 13 and space 13 is formed when it receives compressive stress by the return, etc., of the warpage of a wafer. The layer of the peeled tungsten 12 is removed through etching by a solution. A mixture at the rate of H2O2:HNO3:H2O=1:5:5 is employed as an etchant and the layer of the peeled tungsten 12 is etched. Since a section in which peeling is generated partially in this manner is gotten rid of at a rate of approximately quintuple as fast as the contact hole, tungsten in the contact hole is left, only tungsten on the phospho-silicate glass 13 is taken off, and the surface can be flattened.

Description

Detailed Description of the Invention (Summary) Regarding a method for manufacturing a semiconductor device in which contact holes are filled with tungsten or molybdenum, it is possible to fill contact holes with a filling material having as small crystal grains as possible so that the surface becomes flat. The purpose of the present invention is to provide a semiconductor device manufacturing method in which a contact hole is filled with tungsten, a process of forming tungsten on the entire surface by sputtering to a thickness that can fill the contact hole. A method for manufacturing a semiconductor device characterized by including a step of removing tungsten formed outside the hole and partially peeled off from the base by solution etching, and a method for manufacturing a semiconductor device in which contact holes are filled with molybdenum. Manufacture of a semiconductor device characterized by including a step of forming the entire surface of the contact hole to a thickness that can be filled by sputtering, and a step of removing molybdenum formed outside the contact hole and partially peeled off from the base by solution etching. Contains and constitutes a method.

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device in which contact holes are filled with tungsten or molybdenum.

[Prior Art] Each figure in Figure 2 is a perspective view of the surface of tungsten formed by the CVD method, of which (a) is a state diagram of the deposited state, and (b) is a diagram of the state of deposited tungsten.
Figure 3 shows the state after annealing at 0°C. Each figure is a perspective view of the surface of tungsten formed by sputtering.
a) is the deposited phase diagram, and et al. is the phase diagram after annealing at 1100°C. Note that FIGS. 2 and 3 are drawings based on photographs.

Conventionally, when filling contact holes with tungsten, for example, attempts have been made to use selective chemical vapor deposition (selective C-D) or sputtering (PVD).

However, when actually using tungsten to fill holes using the selective CVD method, filling is possible, but the actual measured average of crystal grains is about 500, compared to 26 in the case of the sputtering method.
This is large compared to about 0, and when contact holes become finer as ICs become more integrated, large crystal grains are not suitable as a burying method. It is desirable that the crystal grains of the embedding material be as small as possible.

Furthermore, referring to the drawings based on the photographs shown in FIGS. 2 and 3, in the case of the sputtering method shown in FIG.
Although the surface is relatively flat and there is no problem in forming the upper layer wiring, in the case of the selective CVD method shown in Fig. 2, the
There are about 2,000 people and 10 times as many irregularities as in the sputtering method, which may cause problems when forming elements with fine structures.

Furthermore, in the case of the selective CVD method, there is a problem in that tungsten tends to erode the substrate surface at the bottom of the contact hole, causing bite.

Therefore, when attempting to fill the contact hole using a sputtering method with small crystal grains and a flat surface, it is difficult to fill the contact hole, and a thick film must be formed to completely fill the contact hole. However, when tungsten is formed thickly, it has poor adhesion to the substrate, so when the wafer returns to its original warpage after sputtering, compressive stress is applied to the tungsten layer, causing it to peel off from the substrate, resulting in uneven waves as shown in Figure 1 (a), which will be explained later. It was impossible to form wiring or the like on top of this.

[Problem to be solved by the invention]

In this way, conventional semiconductor device manufacturing methods have various problems such as undesirable large crystal grains and surface irregularities even when attempting to fill contact holes using selective CVD or sputtering methods, and layer peeling. It was problematic and impractical.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device in which contact holes can be filled with a hole-filling material whose crystal grains are as small as possible so that the surface becomes flat.

[Means for solving the problem] The above problem is solved in a method for manufacturing a semiconductor device in which a contact hole is filled with tungsten. A method for manufacturing a semiconductor device is characterized in that it includes a step of removing tungsten formed in a substrate and peeled off from a base by solution etching, and a method for manufacturing a semiconductor device in which a contact hole is filled with molybdenum. The problem is solved by a method for manufacturing a semiconductor device, which includes the steps of forming molybdenum on the entire surface to a thickness that allows embedding, and removing molybdenum formed outside the contact hole and peeled off from the base by solution etching.

[Effect]

The present invention uses a method in which tungsten or molybdenum is grown on the entire surface by sputtering to a thickness that can fill the contact hole, and tungsten or molybdenum formed outside the contact hole and partially peeled off from the base is removed by solution etching. As a result, small crystal grains and surface flatness, which are the advantages of sputtering embedding, can be obtained, and by solution etching, parts that have peeled off from the thick tungsten or molybdenum layer, which was a problem with sputtering, can be removed. It turns out that it can be removed easily. This is because the etching solution enters the space created by peeling off from the base, increasing the etching speed of the peeled part, and conversely, tungsten and molybdenum remain in the contact hole area where it is most difficult for the etching solution to enter. As a result, as shown in FIG. 1(b), the contact hole was filled with tungsten or molybdenum, and a filled state with a flat surface was obtained.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIGS. 1(a) to (C) are process cross-sectional views of this embodiment. In the figures, 11 is a contact hole, 12 is tungsten, 13 is a phosphorus silicate glass layer, 14 is a silicon substrate,
15 is space, 16 is Affi wiring, and 22 is molybdenum.

In the method of manufacturing a semiconductor device of this embodiment, as shown in FIG. 1(a), a phosphorus silicate glass layer 1 is formed on a silicon substrate
3 is formed with a thickness of 1 μm, and contact holes 11 of 1 μm in length and width are formed by CF through an etching mask (not shown).
Reactive ion etching (RIE) is performed in an atmosphere of 351 secM and CF4485 ecs at an output of 1 and a pressure of 0.3 Torr.

Next, add 0.8 tungsten, which is the embedding material.
It is deposited on the surface using a sputtering method to a thickness of μm. If tungsten is deposited to this thickness, the contact hole can be completely filled. The sputtering equipment used is a single-wafer type sputtering device of the same type as the target wafer, with an output of 4 KW, a pressure of 5 mTorr, and an argon (Ar) sputtering system.
) Sputtering was performed using 40 secM for 120 seconds without heat treatment. When the tungsten layer formed in this way is subjected to compressive stress due to unwarping of the wafer, etc.
As shown in Figure 1(a) (underlying phosphorus silicate glass layer 1)
3 to form a space 15.

The peeled off layer of tungsten 12 is removed by solution etching. Etching solution) 1.0. :IIN
(H: Use a mixture of H2O = 1: 5: 5 and boil at 70°C. At this time, the etching rate for areas other than the contact hole was 4970 people/min, and the etching rate for the inside of the contact hole was 4970 people/min. is 1030 people/min.The parts where partial peeling occurs in this way are removed about five times faster than the contact holes, so the first
As shown in Figure (b), it is possible to flatten the surface by removing only the tungsten on the phosphorus silicate glass 13, leaving the tungsten in the contact hole.

Finally, as shown in Fig. 1 (C), even if the wiring 16 is formed on it, the surface of the base is flat, and the inside of the contact hole is filled with tungsten with small crystal grains and little unevenness. Therefore, contact can be made reliably.

Although tungsten was used as the filling material in this embodiment, molybdenum other than tungsten can also be used to suitably fill the contact hole through the same process as described above.

〔Effect of the invention〕

As described above, according to the present invention, contact holes are filled with tungsten or molybdenum using sputtering, so it is possible to fill holes with a flat surface with small crystal grains, and remove excess material that has peeled off from the base other than the contact holes. The surface of tungsten or molybdenum can be flattened by solution etching, making it possible to form suitable upper layer wiring.

[Brief explanation of the drawing]

FIGS. 1(a) to (C) are process cross-sectional views of the embodiment of the present invention, and FIG. 2 is a perspective view of the surface of tungsten formed by the CVD method, in which (a) is a diagram of the deposited state, and (b) is a diagram of the deposited state. 1100°C
Fig. 3 is a perspective view of the surface of tungsten formed by sputtering, in which (a) is a state diagram of the deposited state, and (■) is a state diagram of 11
FIG. 3 is a state diagram after annealing at 00°C. In the figure, 11 is a contact hole, 12 is tungsten, 13 is a phosphorus silicate glass layer, 14 is a silicon substrate, 15 is a space, 16 is a /l wiring, and 22 is molybdenum.

Claims (2)

[Claims] (1) Fill the contact hole (11) with tungsten (12
), a process of forming tungsten (12) on the entire surface by sputtering to a thickness that can fill the inside of the contact hole (11); A method for manufacturing a semiconductor device, comprising a step of removing peeled tungsten (12) by solution etching. (2) Fill the contact hole (11) with molybdenum (22)
In a method of manufacturing a semiconductor device in which holes are filled with molybdenum (22), the step of forming molybdenum (22) on the entire surface by sputtering to a thickness that allows filling the inside of the contact hole (11); A method for manufacturing a semiconductor device, comprising a step of removing peeled molybdenum (22) by solution etching.