JPH04213818A - Cvd device - Google Patents

Abstract

PURPOSE:To contrive improvement in high accuracy of selective CVD and reproducibility by a method wherein the endpoint judgment in a selective W-CVD method is quantitatively monitored. CONSTITUTION:A susceptor 1 is supported at an inclination angle of (9) as shown in the diagram, and a wafer 3 is retained on the upper surface of the susceptor 1 through a wafer retaining part 2. The change of weight of the wafer 3, in other words, the change in weight of the wafer 3 caused by the selective growth of the tungsten in the aperture such as a contact hole and the like, is detected and the selective CVD endpoint is judged by a signal processing system 7 based on the above-mentioned detected data Da.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CVD apparatus that performs so-called selective W-CVD in which, for example, tungsten is selectively grown to fill minute contact holes and via holes.

0002

2. Description of the Related Art In recent years, as semiconductor integrated circuits have become finer and more highly integrated, the diameters of contact holes and via holes have become smaller, and conventional bias sputtering methods alone can no longer cope with this problem.

[0003]Recently, therefore, so-called PolyP, which selectively fills polycrystalline silicon into the contact holes, etc., has been developed.
Lug technology and the so-called selective W-CVD method for selectively embedding tungsten are attracting attention and are being put into practical use.

In particular, in the selective W-CVD method, a selective growth method (SiH4 reduction method) has been developed that uses a SiH4 reduction reaction that reduces WF6 more easily than the conventional H2 (Si) reduction reaction. The practical application of the W-CVD method is progressing.

However, in order to make the selective W-CVD method a practical technology, various problems remain to be solved, one of which is the end point determination method.

Conventional methods for determining the end point include a method of determining the end point based on the growth time and a method of monitoring the film thickness using a crystal oscillator (Japanese Patent Laid-Open No. 58-217673).
(see publication).

[0007]

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional end point determination method, the method of determining the end point based on the growth time is such that the selective growth time is determined in advance, and when the predetermined time comes, the selective growth by CVD is started. This is a primitive method of stopping, and considering future miniaturization and ultra-high integration of devices, a more quantitative determination method is desired.

On the other hand, the method using a monitor using a crystal oscillator determines the film thickness based on the change in vibration frequency based on the mass of the film attached to the crystal oscillator. The selective W-CVD method described above is suitable for measuring film thickness in the case of vapor deposition, but there are difficulties in its use.

[0009] The present invention has been made in view of the above points, and its object is, for example, to
An object of the present invention is to provide a CVD apparatus that can quantitatively monitor end point determination in a method and perform highly accurate selective growth.

0010

[Means for Solving the Problems] The present invention provides a semiconductor substrate 3
In a CVD apparatus A that selectively grows and embeds a metal layer W in the upper opening 15, a weight detection means 4 detects a change in the weight of the semiconductor substrate 3 based on the growth process of the metal layer W in the opening 15. is installed, and the end point of selective growth is determined based on the detection data Da from the weight detection means 4.

[0011]

[Operation] According to the configuration of the present invention described above, a change in the weight of the semiconductor substrate 3 based on the selective growth of the metal layer W within the opening 15 is detected using the weight detection means 4, and this detected data Da is Since the end point of the selective growth is determined based on this, if the weight data Db of the semiconductor substrate 3 when all the openings 15 are filled with the metal layer W is obtained in advance, the end point can be quantitatively determined. This makes it possible to improve the precision and reproducibility of selective CVD.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a block diagram showing the main parts of a CVD apparatus A according to this embodiment.

This CVD apparatus A is equipped with a susceptor 1 supported at a predetermined inclination angle θ, and a wafer support portion 2 having a U-shape in plan is disposed on the upper surface of the susceptor 1.
is provided.

As shown in FIG. 2, this wafer support section 2 consists of a pair of guide rail sections 2a, 2b and one wafer placement section 2c, and the wafer 3 is placed between the pair of guide rail sections 2a, 2b. After it is inserted by sliding downward,
The wafer placement part 2c prevents the wafer from sliding downward,
The wafer is held by this wafer holding section 2. In this example, wafer 3
The orientation flat surface 3a of the wafer mounting section 2
The wafer 3 is held by the wafer holder 2 so as to be placed on the wafer placement surface 2t of c. Further, the wafer placement section 2c of the wafer holding section 2 has a wafer placement surface 2t.
A piezoelectric element 4 is provided above, and after the weight of the wafer 3 is converted into an electric signal Sa by this piezoelectric element 4,
As shown in FIG. 1, the electric signal Sa is amplified by the amplifier 5, and the digital weight data Sb
After the signal is converted into a signal, it is supplied to a signal processing system 7, which will be described later.

Therefore, the inclination of the susceptor 1, for example, the angle θ between the top surface of the susceptor 1 and the vertical line (indicated by a dashed line)
is made as small as possible so that most of the weight of the wafer 3 becomes a vector component applied to the piezoelectric element 4.

The signal processing system 7 selects C for the wafer 3.
It is for determining the end point of the VD, and includes at least a control section 8, a memory 9, and a calculation section 10.

[0018] This CVD apparatus A is sequence-controlled by a known CVD control system 11.
The VD control system 11 controls starting and stopping of the selected CVD, as well as gas supply timing and the like. Further, a known input means 12 such as a keyboard is connected to the control section 8, and various parameter setting values are input using this input means 12.

Next, the operation of the CVD apparatus A according to this example will be explained with reference to FIG.

First, as shown in the figure, the wafer 3 is placed on the upper surface of the susceptor 1, held by the wafer holding section 2, and the weight of the wafer 3 before selective CVD shown in FIG. 3A is measured. In FIG. 3, 13 indicates, for example, an N-type impurity diffusion region, and 14 indicates an insulating film made of SiO2 or the like.

That is, when the wafer 3 is placed on the wafer placement section 2c, the piezoelectric element 4 outputs an electric signal Sa corresponding to its weight value, and after this electric signal Sa is amplified by the amplifier 5, The A/D converter 6 converts it into digital weight data Sb.

This weight data Sb is stored as current weight data D in the array variable area 9a in the memory 9 via the next control unit 8.
It is stored as initial data of a. At the same time as this initial data is stored in the memory 9, or when the C from the input means 12 is
Based on the VD start command, the control unit 8 outputs a CVD start command signal Sc to the CVD control system 11.

The CVD control system 11 starts selective CVD of tungsten on the wafer 3 based on the input of the CVD start command signal Sc. Conditions for this selective CVD include, for example, WF6/SiH=10/7SCCM, generation pressure 0.2 Torr, and generation temperature 260°C.

Prior to the start of this selective CVD, the weight value when all the tungsten is filled into the openings (contact holes, via holes, etc.) formed on the wafer 3 is determined in advance, and this weight value is input to the input means 12. Enter it using . This weight value is stored in the array variable area 9b in the memory 9 via the control unit 8 as the end point weight data Db.

As described above, while the CVD apparatus A is operating and tungsten W is being selectively grown in the opening 15 as shown in FIG. The weight data Sb is transferred to the array variable area 9a in the memory 9 via the control unit 8, and the current weight data D is stored in the array variable area 9a in the memory 9.
It is stored and updated as a.

The calculation section 10 calculates the difference between the current weight data Da and the end point weight data Db stored in the array variable areas 9a and 9b in the memory 9. When the selective growth progresses and the current weight data Da and the end point weight data Db become the same, that is, when the top surface of the selectively grown tungsten W reaches the top end of the opening 15, as shown in FIG. 3C,
An end point detection signal is output from the calculation unit 10 to the control unit 8. The control unit 8 gives a stop command signal Sd to the CVD control system based on this end point detection signal. The CVD control system 11 controls the CVD apparatus A based on this stop command signal Sd.
The selective CVD of tungsten is completed by performing a series of stopping operations.

Here, the diameter d of the opening 15 is 0.6 μm,
Assuming that the depth h is 0.8 μm and all of these openings 15 are filled with tungsten W, and assuming that the theoretical yield (theoretical yield: chip yield per wafer) is 40 for 4MSRAM, the specific gravity of tungsten W is is about 19.2, so the weight change ΔW≈2.8×10 −3 g. Therefore, it is sufficient for the piezoelectric element 4 to have a sensitivity on the order of mg.

As described above, according to the present example, the susceptor 1 is tilted and supported, and the wafer 3 is held on the upper surface of the susceptor 1 via the wafer holder 2.
The piezoelectric element 4 provided on the wafer placement part 2c detects the weight change of the wafer 3, that is, the weight change of the wafer 3 based on the selective growth of tungsten W in the opening 15, and the signal processing is performed based on this detection data Da. Since the end point of selective growth is determined in system 7, the weight data D of the wafer 3 when all the openings 15 are filled with tungsten W in advance.
By determining b in advance, the end point can be determined quantitatively. This leads to higher precision and improved reproducibility of selective CVD.

In the above embodiment, the piezoelectric element 4 is directly attached to the wafer 3.
The weight change of the wafer 3 was measured by touching the susceptor 1, but in addition, the wafer 3 was suspended along the top surface of the susceptor 1, and the tension of the hanging jig etc. The weight change of the wafer 3 may be measured based on the change. In addition, as a modification of the above embodiment, the upper surface of the susceptor 1 is supported horizontally, and a plurality of piezoelectric elements 4 are mounted on the upper surface.
may be arranged, and the average value obtained by summing up the weight data based on the electrical signals from these piezoelectric elements 4 may be handled as the weight data Da.

[0030]

[Effects of the Invention] According to the CVD apparatus according to the present invention, it is possible to quantitatively monitor the end point determination of selective CVD in, for example, the selective W-CVD method, and to efficiently improve the precision and reproducibility of selective CVD. be able to.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing main parts of a CVD apparatus according to an embodiment.

FIG. 2 is a front view showing main parts of the CVD apparatus according to the present embodiment.

[Fig. 3] Operation of the CVD apparatus according to this embodiment (selective CVD
) is a progress chart showing.

[Explanation of symbols]

A CVD equipment 1 Susceptor 2 Wafer holding part 2a, 2b Guide rail part 2c Wafer placement part 3 Wafer 4 Piezoelectric element 7 Signal processing system 11 CVD control system 15 Opening

Claims (1)

[Claims] 1. In a CVD apparatus for selectively growing and embedding a metal layer in an opening on a semiconductor substrate, a weight for detecting a change in the weight of the semiconductor substrate based on the growth process of the metal layer in the opening. 1. A CVD apparatus comprising a detection means, and determining the end point of selective growth based on detection data from the weight detection means.