JPH0353076A - Mechanism for controlling heating of semiconductor substrate for cvd device - Google Patents

Abstract

PURPOSE:To suppress the growth of hillock in the heating state before film formation by providing means for temporarily parting a semiconductor substrate carried into a reaction chamber from a heating body. CONSTITUTION:An upper electrode 4 and a lowe electrode 5 are disposed on the reaction chamber 2 of the CVD device and a heater 6 is built atop the lower electrode 5. A pair of lifting pins 7, 8 as the parting means are perpendicularly disposed through the heater 6 and the lower electrode 5. The semiconductor substrate 3 carried into the reaction chamber 2 from the aperture thereof is imposed on the lifting pins 7, 8. After the flow rate of the reaction gases and internal pressure in the reaction chamber 2 are stabilized, the lifting pins 7, 8 are lowered to impose the semiconductor substrate 3 onto the upper surface 6a of the heater at the point of the time just before about 10 seconds from the point of the time when the film formation starts. The semiconductor substrate 3 is heated by the heater 6. The substrate is heated up to the target temp. at the point of the time when the film formation starts.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a CVD apparatus that forms various types of films on a semiconductor substrate by the CVD method. Good insulation on metal wiring! Plasma CV capable of forming films, protection 111iA, etc.
This relates to the D device.

[Conventional technology]

As a CVD (vapor phase chemical reaction generation) device, a heating element such as a heater placed in the reaction chamber heats a semiconductor substrate placed in the reaction chamber in the form of a thin film to a temperature at which it can be thermally decomposed. A structure having this structure is known. In such CVD equipment, first of all. The semiconductor substrate carried into the reaction chamber is placed on a stage equipped with a heating element and heated to a certain temperature required for thermal decomposition, e.g. 400°C.
In parallel with this heating operation,
The flow rate of the reaction gas supplied into the reaction chamber is stabilized, the pressure inside the reaction chamber is stabilized at a target level, and then discharge between the electrodes in the reaction chamber is started to form a film on the surface of the semiconductor substrate. That's what I do. In such a film formation start process, the semiconductor substrate is usually quickly heated to the target temperature by a heating element, and the semiconductor substrate waits in this heated state until the flow rate and pressure of the reaction gas in the reaction chamber are stabilized. It turns out. P [Problems to be Solved by the Invention] However, when such a CVD apparatus is used to form an insulating film on, for example, aluminum wiring on a semiconductor substrate, the following problems occur. In other words, if the semiconductor substrate is kept under constant heating as described above until the flow rate and pressure of the reaction gas in the reaction chamber are stabilized, aluminum crystals will grow on the semiconductor substrate during this time to a point that cannot be ignored. There is a risk that it will happen. If such a situation occurs, short circuits will occur between the aluminum wiring lines, and the reliability of the semiconductor substrate after forming the insulating film will be significantly lowered, which is undesirable.

In order to solve this problem, in the past, a bypass circuit was attached to the flow path of the reaction gas to keep the reaction gas flowing at all times, so that the reaction gas could be brought into the reaction chamber within a short time after the semiconductor substrate was carried into the reaction chamber. Proposals have been made to stabilize the gas flow rate of the semiconductor substrate, thereby shortening the time during which the semiconductor substrate is in a heated state. However, this method consumes a huge amount of reaction gas and is not practical.

In view of the above points, it is an object of the present invention to provide a CVD apparatus that can avoid the occurrence of undesirable hillocks when forming a thin film on metal wiring formed on a semiconductor substrate by the CVD method. It is about realization.

[Means to solve the problem]

above! In order to solve problem I, the present invention provides a CVD system in which a heating element for heating a semiconductor substrate is installed in a reaction chamber.
The apparatus is characterized in that it includes a separating means for temporarily separating the semiconductor substrate carried into the reaction chamber for film formation from the heating body.

[Effect]

In the apparatus of the present invention having this structure, film formation may be performed as follows. That is, after the semiconductor substrate is carried into the reaction chamber, it is not immediately exposed to the heating state by the heating element, but is separated by the spacing means to a position where it will not be heated by the heating element. In this state, the semiconductor substrate is placed on standby. Then, once the gas flow rate and pressure in the reaction chamber have stabilized, or slightly earlier than this point,
The separation state of the semiconductor substrate by the separation means is canceled, the semiconductor substrate is placed at a position where it can be heated by the heating body, and the semiconductor substrate is heated to a target temperature. After the gas flow rate and pressure in the reaction chamber are stabilized and the semiconductor substrate is heated to a target temperature, film formation is started.

In this way, by using the spacing means, it is possible to shorten or, in fact, qualitatively eliminate the time required to wait until the start of a certain film while the semiconductor substrate is in a heated state, and in this heated state, hillocks that occur in the metal wiring on the semiconductor substrate can be This makes it possible to suppress the precepts to an acceptable level.

〔Example〕

The internal configuration of a reaction chamber for explaining an embodiment of the present invention with reference to the drawings is shown below, and the apparatus of σ11 is for forming an oxide film on a semiconductor substrate on which aluminum wiring is formed. It is. The reaction chamber 2 of the cD device 1 of this example is as follows:
It has an opening for taking in and taking out the semiconductor substrate 3, and also has a reaction gas inlet/outlet for circulating the reaction gas in the reaction chamber and a vacuum exhaust port for reducing the pressure inside the reaction chamber to a constant pressure level. Since this is a generally known structure, illustration thereof is omitted and detailed explanation thereof will also be omitted here. In the reaction chamber 2, an upper electrode 4 and a lower electrode 5 are arranged vertically with an interval between them. A heater 6, which is a heating element, is built into the upper surface of the lower electrode 5, and the horizontal upper surface 6a of the heater 6 serves as a stage on which the semiconductor substrate 3 is placed.

Here, a pair of push-up pins 7 and 8 as a separating means for separating the semiconductor substrate 3 from the heater 6 are disposed vertically extending vertically through the heater 6 and the lower electrode 5. These pair of push up bottles are OM7
From the retracted position where a and 8a are flush with the heater top surface 6a,
As shown in the figure, it is movable from the heater top surface 6a to a protruding position that protrudes a certain amount upward. As the drive mechanism for moving the bin in this manner can be a generally known mechanism, it is omitted from the drawings and detailed explanation thereof will also be omitted.

In addition, in this example, (Si114
+N20 +8r) gas is introduced,
The reaction chamber is filled with l.o.p. by the vacuum evacuation system. The pressure is reduced to OTorr, and the semiconductor substrate is heated to about 400 Torr by the heater 6 during film formation.
It is heated to ℃. Plasma is generated by applying a high frequency to the upper electrode 4, and an oxide film is formed on a semiconductor substrate having aluminum wiring formed on its surface, for example.

The operation up to the start of membrane formation in a device with this configuration will be described.

First, go to the initial state! Then, the push-up bottles 7 and 8 were set at their protruding positions, and the semiconductor v! was carried into the reaction chamber 2 through the opening. ．． The board 3 is placed on these push-up bins 7 and 8. Thereafter, circulation of the reaction gas is started within the reaction chamber 2, and the pressure inside the reaction chamber is reduced to a target value. In this example, the push-up bottle 7
, 8 are lowered and set at their retracted positions, and the semiconductor substrate 3 is
is placed on the stage (heater top surface 6a).

As a result, the semiconductor substrate 3 is heated by the heater 6, and e. At the start of the film, it will be heated to the target temperature (approximately 400° C.). In this manner, after the conditions for starting film formation are established, a high frequency wave is applied between the electrodes to start forming a certain film.

In this way, according to the apparatus of this example, the waiting time while the semiconductor substrate remains in a heated state is shortened before starting film formation. Therefore, before the hillocks become unacceptably large, film deposition is started and an oxide film is formed on the semiconductor substrate, and the shape of this oxide film suppresses further growth of the hillocks. Incidentally, in the apparatus of this example, if the semiconductor substrate is placed on the stage immediately after being placed in the reaction chamber as in the conventional method, it will take approximately 1 liter to reach a constant flow rate of the reaction gas and the pressure in the reaction chamber. It is necessary to wait in the heated state for about a minute, during which time the aluminum hillocks become unacceptably large.

In the above example, heating is started approximately 10 seconds before the heating start time, but this heating start time has a property that should be specified separately for each device, and in particular, The optimum value should be set based on the relationship between the temperature of the semiconductor substrate at the start of film formation and the length of hillock IIi. Furthermore, it goes without saying that a mechanism other than the pair of push-up bottles described above may be employed as a mechanism for separating the semiconductor substrate carried into the reaction chamber from the heating element.

Further, in the above example, an apparatus for forming an oxide film on a semiconductor substrate by the CVD method was used as an example, but the present invention is applicable to e.g. when forming a thin film by the CVD method. Of course, this method can be applied to cases where it is necessary to suppress heating of the semiconductor substrate before the film.

〔Effect of the invention〕

As explained above, in the present invention, a separating means is provided to temporarily separate the semiconductor substrate carried into the reaction chamber from the heating element disposed therein, so that The time period during which the semiconductor substrate is kept in a heated state at a predetermined temperature can be shortened, and therefore, the length of hillocks in the heated state before a certain film can be suppressed.

Explanation of symbols l-...CVD equipment 21 reaction chamber 3.1 Semiconductor substrate 4, 5 one electrode 6.1.Heater (heating body) 7, 8 One push bottle (Separation means) father-in-law

Claims (1)

[Claims] A CVD apparatus in which a heating element for heating a semiconductor substrate is installed in a reaction chamber, comprising a separating means for temporarily separating the semiconductor substrate carried into the reaction chamber for film formation from the heating element. A semiconductor substrate heating control mechanism for a CVD apparatus, characterized in that: