JPS6247135A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent an Si3N4 film from cracking by forming a CVD film, heat-treating before forming the Si3N4 film, and thermally shrinking the CVD film. CONSTITUTION:A CVD SiO2 film 9 is formed on an Si substrate in which elements have been formed, heat treated at 800 deg.C for 10-20min to thermally shrink the film 9. Then, an Si3N4 film 10 is coated by a reduced pressure CVD method, and an AsSG film 11 is superposed as H blocking film and reflowing film at low temperature. Since the film 9 has been already annealed even if heated in case of reflowing, no crack occurs in the film 10. Accordingly, H2 invasion blocking force is enhanced. Then, even if a plasma Si3N4 film 12 which contains the H is coated, the element in the lower portion is stably operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a high quality semiconductor device in which an insulating film such as a silicon nitride film is formed between layers.

[Summary of the invention]

This invention provides a method for manufacturing a semiconductor device in which a silicon nitride film is formed on a CVD film and a film containing hydrogen is further formed on top of the silicon nitride film. By subjecting the CVD film to thermal contraction, cracks are prevented from occurring in the silicon nitride film.

[Conventional technology]

In a method of manufacturing a semiconductor device, a plasma nitride film is used as an overcoat film to improve quality. This plasma nitride film is harder than a silicon oxide film or PSG (phosphorus silicate glass), and is highly effective in blocking the permeation of impurities and moisture.

However, a large amount of hydrogen exists in this plasma nitride film. Therefore, in order to block the influence of this large amount of hydrogen on the semiconductor element, a silicon nitride film is formed between the glue flow film such as PSG and the silicon oxide film formed on the element E.

Here, a conventional method for manufacturing a semiconductor device will be described with reference to FIG.

First, a predetermined element bone M6N region, a source,
After forming drain, gate electrodes, etc., and forming predetermined wiring electrodes, etc., a 5iQ2CVI) film is formed as an interlayer insulating film (SiOzCVI) film formation step Ql). This S
Formation of the iO*CVD film is performed by a normal CVD method.

Subsequently, as described above, a silicon nitride film (Si3N4) is formed to block the influence of hydrogen on the semiconductor element (silicon nitride film forming step Q2). This silicon nitride film is formed by reacting a predetermined gas with, for example, a low pressure CVD method.

Next, a PSG film is deposited as a reflow film (PSG film formation stage Q3). Then, the PSG film is reflowed by heat treatment at a predetermined temperature (reflow step Q4).

Furthermore, as described above, a plasma nitride film is deposited as an overcoat film to prevent the permeation of impurities and moisture (plasma nitride ring forming step Q5).
. In addition, before the plasma nitride ring forming step Q5,
Although there are steps such as forming a wiring layer, their explanation will be omitted.

A semiconductor device is manufactured through the above steps 01 to Q5.

[Problem that the invention seeks to solve]

The silicon nitride film is formed to block the influence of the plasma nitride film containing hydrogen, but it has the problem of microcracks occurring due to heat treatment.

That is, as shown in FIG. 4, a semiconductor device manufactured by the conventional semiconductor device manufacturing method includes, for example, an element formation layer 20, which is a region where elements are formed, in order from the bottom, CV
It has a laminated structure including a 5i02CVD film 21 formed by the D method, a silicon nitride film 22, a PSG film 23 which is a reflow film, and a plasma nitride film 24 which is an overcoat film.

Here, the silicon nitride film 22 is provided to prevent impurities 25 such as hydrogen from entering from the plasma nitride film 24 as described above.

Furthermore, due to the demand for lower process temperatures, an As5G film is sometimes used in the reflow film instead of the PSG film 23, but in this case, negative charges may be generated in the As5G film, and such adverse effects may occur. In order to prevent this, it is necessary to form a silicon nitride film 22 between the 5i02CVD film 21 and the reflow film to stabilize the semiconductor device.

However, when heat treatment such as reflow or sintering is performed, the silicon nitride film 22 has a 5i0
The shrinkage of the volume of the 2CVD film 21 by about 10% causes distortion and cracks. The thermal contraction of the 5iO2CVD film 21, which is the cause of this crack, is 5i02CV
It is thought that this occurs because the D film 21, that is, the silicon oxide film, is formed by the CVD method, and therefore the CVD film itself lacks density.

On the other hand, increasing the thickness of the silicon nitride film 22 does not solve the problem. That is, silicon nitride film 2
If the thickness of the silicon nitride film 22 is increased (for example, if the film is deposited with a thickness of 2000 Å or more), the silicon nitride film 22 to be formed may become distorted due to its own stress and cracks may occur. This is because there is a limit to the thickness.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a method for manufacturing a semiconductor device that can manufacture a semiconductor device that does not generate cracks even when subjected to heat treatment such as reflow or sintering. .

[Means for solving problems]

The present invention includes a step of forming a CVD film on a semiconductor substrate;
The above-mentioned problems can be solved by a semiconductor device manufacturing method comprising the steps of heat-treating the CVD film, forming a silicon nitride film on the CVD film, and forming a film containing hydrogen on top of the silicon nitride film. solve.

[Operation] After the CV D film is formed on the semiconductor substrate, the CV I) film is subjected to heat treatment before the silicon nitride film is deposited. This heat treatment causes the CVD film to shrink, and in the heat treatment that cannot be carried out in a later step, a heat loss of 1M relative to the c v +]If can be obtained by 1r11. Since a silicon nitride film, a hydrogen-containing film, or the like is formed on the CVN film that has been once thermally shrunk in this manner, it is possible to suppress problems such as cracks occurring, especially in the silicon nitride film.

〔Example〕

Preferred embodiments of the present invention will be described with reference to the drawings.

The method of manufacturing a semiconductor device of this embodiment relates to a method of manufacturing a high-quality semiconductor device by preventing the occurrence of cranks in a silicon nitride film through the process order shown in FIG.

First, in the process of manufacturing a semiconductor device, various regions such as an element region, a source region, a train region, a notch oxide film, and a cable are formed in predetermined regions of a semiconductor substrate. As shown in FIG. 1, a 5i02CVD ridge-forming culm P1 is formed by depositing a 3i02CV l) film, which is an interlayer film covering these various regions.

The 5iO2 CVD film is formed by depositing 5i02 from a reaction gas using, for example, the usual CI] method. The film quality is such that it shrinks due to heat treatment.

The next step after the 5i02CVD film forming step PI is the 72-rue step P2.

This annealing step P2 is performed before the deposition of a silicon nitride film used as a blocking film for hydrogen, etc.
The 2CVD film is annealed to cause the 5iO2CVD film to shrink. The annealing conditions are the usual annealing conditions (4 is sufficient, for example, 800°C 1 meter, 10~
It can be done in 20 minutes.

Following such an annealing process 1) 2, hydrogen +111
In the case where an As5G film (deposited in the next step) is used as a reflow film, the silicon nitride film (Si3N4) is formed in step P3 to block the influence of negative charges. The warp:I nitride film is formed by deposition from a reactive gas using, for example, a low pressure CVN method. The underlying 5i02CVD film at this time has been annealed and thermally shrunk in the annealing step P2, so even if the silicon nitride film is subjected to the heat treatment that will be carried out in the subsequent steps, the silicon nitride No harmful effects such as cracks on the film occur.

The next step after the silicon nitride film forming step P3 is the As S G film forming step P4. The As3Q film is formed for reflow, and when As5G is used, PSG
It can be processed at a relatively low temperature compared to the previous method, and it is possible to miniaturize semiconductor devices.

Subsequently, the As5GIQ formed in the As S G film forming step P4 is reflowed to planarize the As S G film. During this reflow king culm P5, C12 is
The entire substrate on which the semiconductor device is formed is heated, and conventionally, as mentioned above, the 5iO2CVD film shrinks and cracks occur in the silicon nitride film, which is a disadvantage. Since the l-3 film is annealed, f'> tsuk occurs in the silicon nitride film.
There's not a single difference.

After this reflow step 1>5, a plasma nitride 1 film is formed as a hydrogen-containing film as an overcoat film (plasma nitride formation step 1).
6). Although this plasma night film contains a large amount of hydrogen, the silicon nitride film is prevented from cracking by the manufacturing method of the semiconductor device of this example, and this crack-free film prevents cracks from occurring in the silicon nitride film. Since the ability to prevent impurities such as hydrogen from entering is increased, the semiconductor element below can operate stably.

The manufacturing method of the semiconductor device of this example can be realized through the steps described in J2 below, and crack generation can be sufficiently prevented by simply adding the annealing step P2 to the conventional process. It is something.

In order to make this embodiment more clear, an example in which this embodiment is used as a semiconductor device 2 for SRAM will be described with reference to FIG.

SRAM suitable for applying this embodiment is, for example, the second
The structure shown in the figure can be adopted. However, as a ``1-dedicated basis'', a material base such as silicon (1y1) is provided with an element r isolation region 4, a source region 2, an in/in region 3, a gate oxide film 6, and a gate electrode. 5 or the like is formed, and is covered with an interlayer insulating film 7.A 4A film such as polysilicon is formed on a predetermined portion on this interlayer insulating film 7.
A high-resistance element 8 formed of is patterned. 8. A 5i(), CVI) film 9 is deposited to cover the second high paper 1iC body 8 and the interlayer insulating film 7, and a silicon nitride film 10 is deposited to cover the 5i02CVI) film. I'm nestling. The silicon nitride film IO is 5i
After the O2CVD film 9 is deposited, it is formed through the annealing step (steps 1 and 2) described above. Therefore, even during reflow coating or non-talling, there is no problem such as crank emission L1, and impurities are effectively removed. It is possible to suppress negative effects.

A part of the silicon nitride film 100)-1 has a rift 11-
An ASSG film 11 that can be reflowed at a low temperature is formed to have a predetermined thickness. Then, A s S (
'; On the entire surface of the membrane II (J, plasma 1
is formed by adhesion.

An SRAM with such a structure uses a silicon nitride film 10
If no annealing treatment is performed before the formation of 5i0
There is a problem that clicks occur due to the absorption of 2CVDl model 9, and moreover, the reflow film is
Since I is used, there is a problem in that negative charges are also generated due to the intrusion of impurities from the plasma nitrite film 12. However, by applying the semiconductor device manufacturing method of this embodiment, s is applied before forming the silicon nitride film IO.
+o2cvnllg9 is annealed to shrink the film volume, and then a silicon nitride film lO is formed.
No cranking occurs during heat treatment such as 'J-', and harmful effects such as the intrusion of impurities such as hydrogen from the plasma nitride film 12 and the generation of negative charges are prevented. Since the intrusion of impurities is effectively suppressed in this way, for example, the parts such as the antibody 8 can operate stably, and the ``I'' and A!j body elements can also be reliable. It becomes a device with high trajectory.

Incidentally, the method for manufacturing a semiconductor device of the present invention is as follows.
The present invention is not limited to RAM, but can be applied to all semiconductor devices that use a hydrogen-containing film as an interlayer or overcoat film, and can provide a semiconductor device that does not generate cracks and has an excellent ability to prevent impurity penetration. can.

Further, the hydrogen-containing film is not limited to plasma nitride, and may be any other hydrogen-containing film. , BSG, 5bSG, PSG, etc. may be used.

Furthermore, the hydrogen-containing film is not limited to that used as an overcoat film, and a hydrogen-containing film may be formed between layers, and in this case as well, annealing treatment is performed before forming the silicon nitride film. The predetermined effects of the present invention can be achieved depending on the conditions.

〔Effect of the invention〕

In the semiconductor device manufacturing method of the present invention, since the CVD film is heat-treated during the formation 111 of the silicon nitride film, it is possible to eliminate problems such as cracks in the silicon nitride film, and to ensure highly reliable and stable operation. It is possible to manufacture a semiconductor device. Further, it is sufficient to add an annealing step, and an excellent semiconductor device can be manufactured using the existing step 1.

[Brief explanation of drawings]

FIG. 1 is a process diagram relating to the method of manufacturing a semiconductor device of the present invention, and FIG. 2 is a schematic cross-sectional view showing an example of a semiconductor device suitable for manufacturing using the method of manufacturing a semiconductor gW of the present invention. , Figure 3 shows the steps of the conventional manufacturing method for semiconductor pictures.
・It is a process diagram showing an example, and No. 41x1 is a schematic diagram showing an example of the structure of a semiconductor device. 1) 2... Annealing process)) 3... Silicon nitride film formation process P6...・Brasmanai I-light formation] Culm 1...Substrate 9...S i 02 CVD film (CVD film) 10.
...Silicon nitride film 11...As5G film 12...Plasma nitride film 12 Applicant: Sony Corporation 11 Agent
Patent attorney Koike Miumi Tamura Sakae - Musashiranq's 117 books in the year≠EδV-'s 11--V
Sankari, OJ Soshi] Figure 1 T Fu # Cane! An example #E2 figure

Claims (1)

[Claims] A step of forming a CVD film on a semiconductor substrate, a step of heat-treating the CVD film, a step of forming a silicon nitride film on the CVD film, and a step of forming a film containing hydrogen on the silicon nitride film. A method for manufacturing a semiconductor device comprising: