Abstract:
A vapor reaction method including the steps of providing a pair of first and second electrodes within a reaction chamber where the pair of electrodes are arranged substantially parallel with each other. The method further includes the steps of placing a substrate in the reaction chamber where the substrate is held by said first electrode so that a first surface of the substrate faces toward the second electrode. A first film forming gas is introduced into the reaction chamber through the second electrode. The first film forming gas is excited to form a first insulating film by vapor deposition. The first insulating film may be silicon nitride. The method may also include the step of introducing a second film forming gas into the reaction chamber through the second electrode to ultimately form a second film. After removing the substrate from the reaction chamber, a cleaning gas may then be introduced through the second electrode to remove unnecessary layers from the inside of the reaction chamber.

Description:
This application is a DIV of Ser. No. 08/659,636 Jun. 6, 1996 ABN which is a DIV of Ser. No. 08/351,140 Nov. 30, 1994 U.S. Pat. No. 5,650,013 which is a CON of Ser. No. 08/064,212 May 12, 1993 ABN which is a DIV of Ser. No. 07/842,758 Feb. 28, 1992 ABN which is a CON of Ser. No. 07/595,762 Oct. 3, 1990 ABN which is a CON of Ser. No. 07/312,420 Feb. 21, 1989 ABN which is a CON of Ser. No. 07/092,130 Sep. 2, 1987 ABN which is a DIV of Ser. No. 06/801,768 Nov. 26, 1985 ABN. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a layer member forming method which is suitable for use in the fabrication of various electronic devices of the type having an insulating, protecting, conductive, semiconductor or like layer member formed on a substrate member. 
   2. Description of the Prior Art 
   Heretofore there has proposed a method for forming such a layer member on a substrate member through use of a photo CVD or plasma CVD process. 
   According to the method utilizing the photo CVD technique, the substrate is placed in a reaction chamber provided with a light transparent window and a reactive gas mixture, which contains at least a gas of a material for the formation of the layer member desired to obtain, is introduced into the reaction chamber. Then light is introduced into the reaction chamber through the light transparent window thereof by which the reactive gas mixture introduced thereinto is excited for vapor-phase decomposition and the material for the layer is deposited on the substrate member. 
   With the method utilizing the plasma CVD technique, the substrate is placed in a reaction chamber and a reactive gas mixture, which contains a gas of a material for the formation of the layer, is introduced into the reaction chamber. In the reaction chamber the reactive gas mixture is excited into a plasma by grow discharge or electron cyclotron resonance for vapor-phase decomposition by high frequency electric power so that the material for the layer is deposited on the substrate. 
   With the photo CVD process, since the material gas resulting from the vapor-phase decomposition of the photo-excited reactive gas is not accelerated, it is possible to form the layer on the substrate with substantially no damage inflicted on the substrate surface. On this account the layer can easily be formed without containing the material forming the substrate surface or without introducing into the substrate surface the material forming the layer, without developing any undesirable interface level between the layer and the substrate and without applying any internal stress to the layer and the substrate. Furthermore, since the photo-excited material gas has a characteristic to spread on the surface of the substrate member, the layer can be deposited in close contact with the substrate even if the substrate surface is uneven. 
   Accordingly, the use of the photo CVD technique permits easy formation of the layer of desired characteristics, without causing any damages to the substrate surface, even if the substrate has an uneven surface. 
   With the photo CVD process, however, since the photo-excited material gas is not accelerated toward the substrate, the deposition rate of the layer is lower than in the case of employing the plasma CVD technique. Therefore, the photo CVD process takes much time for forming the layer as compared with the plasma CVD process. Furthermore, the material for the layer is deposited as well on the light transparent window during the formation of the layer, causing a decrease in the light transmittivity of the window as the deposition proceeds. Therefore, the layer cannot be formed to a large thickness. For instance, in the case of forming a silicon nitride layer, it is difficult, in practice, to deposit the layer to a thickness greater than 1000 A. Moreover, difficulties are encountered in forming a silicon layer to a thickness greater than 200 A, a silicon oxide (SiO 2 ), or aluminum nitride (AlN) layer to a thickness greater than 3000 A, a silicon carbide (Si xC     1-x   , where 0&lt;x&lt;1) layer to a thickness greater than 500 A and a germanium silicide (Si x Ge 1-x , where 0&lt;x &lt;1) or metal silicide (SiM x , where M is metal such as Mo, W, In, Cr, Sn Ga or the like and 0&lt;X≦4) layer to a thickness greater than 100 to 200 A. 
   with the plasma CVD process, since the material gas resulting from the vapor decomposition of the reactive gas excited by electric power can be accelerated toward the substrate, the deposition rate of the layer is higher than in the case of using the photo CVD process. Therefore, the layer can be formed on the substrate in a shorter time than is needed by the photo CVD technique. Furthermore, even if the material for the layer is deposited on the interior surface of the reaction chamber as well as on the substrate, no limitations are imposed on the excitation of the reactive gas by electric power. Consequently, the layer can easily be formed to a desired thickness on the substrate. 
   With the plasma CVD technique, however, since the material gas excited by electric power is accelerated by an electric field, it is difficult to deposit the layer on the substrate without causing damage to its surface. On account of this, the layer contains the material forming the substrate surface, or the substrate surface contains the material forming the layer. Moreover, an interface level is set up between the layer and the substrate and internal stresses are applied to the layer and the substrate. 
   Besides, in the case of employing the plasma CVD technique, since the excited material gas is accelerated by an electric field and its free running In the reaction chamber is limited, there is the possibility that when the substrate surface is uneven, the layer cannot be formed in close contact therewith, that is, the layer cannot be deposited with desired characteristics. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a novel layer member forming method which is free from the abovesaid defects of the prior art. 
   The layer member forming method of the present invention comprises the steps of depositing a layer of a desired material on a substrate by the photo CVD technique and depositing on the first layer a second layer of a material identical with or different from that of first layer by the plasma CVD technique, thereby forming a layer member composed of at least the first and second layers. 
   According to such a method of the present invention, since the first layer is deposited by the photo CVD technique on the substrate, even if the substrate surface is uneven, the first layer can be deposited in close contact with the substrate surface and with substantially no damage thereon. Accordingly, the first layer does not substantially contain the material forming the substrate surface, or the substrate surface does not substantially contain the material forming the first layer. Further, the deposition of the first layer is not accompanied by provision of an undesirable interface level between the first layer and the substrate and the application of internal stresses to the first layer and the substrate. In addition, since the second layer is deposited by the plasma CVD technique on the first layer, the second layer can easily be formed to a desired thickness in a short time. 
   In accordance with an aspect of the present invention, by forming the first and second layers as insulating, protecting or conductive layers of the same or different types or compositions, the layer member as a insulating, protecting or conductive layer member of desired characteristics can easily be deposited to desired thickness in a short time without inflicting damage on the substrate surface. 
   In accordance with another aspect of the present invention, by forming the first and second layers as semiconductive layers of the same type or composition, the layer member as a semiconductor layer member can easily be deposited to a desired thickness in a short time without inflicting damage to the substrate surface. 
   In accordance with another aspect of the present invention, by forming the first and second layers as semiconductor layers of different types or compositions, the layer member can easily be deposited as a semiconductor layer member composed of a first semiconductor layer which may preferably be relatively thin and a second semiconductor layer which may preferably be relatively thick, in a short time without causing damage to the substrate surface. 
   In accordance with another aspect of the present invention, by forming the first and second layers as an insulating layers and as a conductive or semiconductor layer, respectively, the layer member as a composite layer member can easily be deposited including a conductive or semiconductor layer formed to a desired thickness on the insulating layer of the least possible thickness, in a short time without impairing the substrate surface. 
   In accordance with yet another aspect of the present invention, by forming the first and second layers as a conductive or semiconductor layer and as an insulating or protecting layer, respectively, the layer member as a composite layer member can easily be deposited including an insulating or protecting layer formed to a desired thickness on the conductive or semiconductive layer of the least possible thickness, in a short time without impairing the substrate surface. 
   Other objects, features and advantages of the present invention will become more fully apparent from the following description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The accompanying sheet of a drawing schematically illustrates an example of the layer forming method of the present invention and an example of apparatus used therefor. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description will be given first of an apparatus for the formation of a layer member according to the present invention. 
   The apparatus has a conductive reaction chamber  10 . The reaction chamber  10  is provided with a plurality of conductive nozzles  11  arranged at the lower portion of the chamber  10  and each having upper and lower nozzle parts  12   a  and  12   b . The conductive nozzles  11  are connected to one end of a power supply  15  for gas excitation. 
   A gas introducing pipe  13  is connected to the upper nozzle parts  12   a  of the nozzle  11  and extends out of the reaction chamber  10 . The gas introducing pipe  13  is connected to a gas source  14 A via a valve  15 A and a flowmeter  16 A and to another gas source  14 B via a valve  15 B and a flowmeter  16 B. 
   Another gas introducing pipe  17  is connected to the lower nozzle parts  12   b  of the nozzle  11  and extends out of the reaction chamber  10 . The gas introducing pipe  17  is connected to a gas source  18 A via a valve  18 A and a flowmeter  20 A, to a gas source  18 B via a valve  19 B and a flowmeter  20 B and to a gas source  18 C via a valve  19 C and a flowmeter  20 C. 
   The reaction chamber  10  is provided with an exhaust pipe  21  which extends to the outside through the bottom wall of its extending portion  10 ′ wherein the nozzles  11  are not placed. The exhaust pipe  21  is connected to a vacuum pump system  22  via a control valve  23  and a change-over valve  24 . The vacuum pump system  22  has a tandem structure of a turbo pump  25  and a rotary pump  26 . 
   Provided on the bottom wall of the reaction chamber  10  is a light source chamber  30 , in which is disposed light sources  31  each of which emits light having a wavelength 300 nm or less, such as a low pressure mercury lamp. The light sources  31  are connected to an external power supply (not shown). Provided on the bottom wall of the chamber  30  are cooling pipes  51  which are connected to a cooling tower (not shown). 
   The reaction chamber  10  and the light source chamber  30  optically intercommunicate through a window  33  made in, for instance, a quartz plate disposed therebetween. 
   The light source chamber  30  has a gas introducing pipe  34  which extends to the outside through its one end portion of the bottom wall. The gas introducing pipe  34  is connected to a gas source  35  via a valve  36  and folwmeter  37 . The light source chamber  30  has an exhaust pipe  38  which extends from the other end portion of the bottom wall of the chamber  30  into the extending portion  10 ′ of the reaction chamber  10 . A heater  39  is provided on the exhaust pipe  38 . 
   Disposed on the upper wall of the reaction chamber  10  is a heat source chamber  40 , in which is disposed a heat source  41  formed by, for example, a halogen lamp. The heat source  41  is connected to an external power supply (not shown). Provided on the top wall of the chamber  40  is costing pipes  61  which are connected to the abovesaid costing tower. 
   The reaction chamber  10  and the heat source chamber  40  thermally intercommunicate through a window  43  made in, for example, quartz plate disposed there between. 
   The light source chamber  40  has a gas introducing pipe  44  which extends through its one end portion of the upper wall to the outside and is connected to abovesaid gas source  35  via the valve  36  and the flowmeter  37 . The heat source chamber  40  has an exhaust pipe  48  which extends from its other end portion of the upper wall into the extending portion  10 ′ of the reaction chamber  10 . A heater  49  is provided on the exhaust pipe  48 . 
   The reaction chamber  10  has attached thereto on the side of its extending portion  10 ′ a substrate take-in/take-out chamber  70  with a shutter means  71  interposed therebetween. The shutter means  71  is selectively displaced to permit or inhibit the intercommunication therethrough between the chambers  10  and  70 . 
   The chamber  70  has another shutter means  72  on the opposite side from the shutter means  71 . The chamber  70  has an exhaust pipe  73  which extends from its bottom to the vacuum system  22  via the aforementioned change-over valve  24 . The chamber  70  has another pipe  75  which extends to the outside and terminates into the atmosphere via a valve  76 . 
   The apparatus includes a conductive holder  81  for mounting a plurality of substrate members  90 . The holder  81  is combined with thermally conductive press plates  82  for placing on the substrate members  90  mounted on the holder  81 . 
   According to an example of the present invention, the abovesaid layer member is deposited on the substrate member  90  through use of such an apparatus, as described hereinafter. 
   Embodiment 1 
   A description will given of a first embodiment of the present invention for forming the layer member as a insulating layer member on the substrate member  90 . 
   (1) The shutter means  71  between the reaction chamber  10  and the substrate take-in/take-out chamber  70 , the shutter means  72  of the chamber  70  a valve  76  between the chamber  70  and the outside, the valves  15 A and  15 B between the nozzle parts  12   a  and the gas sources  14 A and  14 B, the valve  19 A,  19 B and  19 C between the nozzle parts  12   b  and the gas sources  18 A,  18 B and  18 C and the valve  36  between the chambers  30  and  40  and the gas source  35  are closed. 
   (2) Next, the valve  23  between the reaction chamber  10  and the vacuum pump system  22  is opened and change-over valve  24  is also opened to the both chambers  10 ,  70 ,  30  and  40  to a pressure of 10 −7  Torr. 
   (3) Next, the turbo pump  25  and the rotary pump  26  of the vacuum pump system  22  are activated, evacuating the chambers  10  and  70 . 
   (4) Next, the valve  23  is closed and the change-over valve  24  is also closed relative to the both chambers  10  and  70 , followed by stopping of the vacuum pump system  22  from operation. 
   (5) Next, the valve  76  is opened, raising the pressure in the chamber  70  up to the atmospheric pressure. 
   (6) Next, the shutter means  72  is opened, through which the substrate  90  mounted on a holder  81  with, its surface for the formation thereon of the layer held down, is placed in the chamber  70  with a press plate  82  mounted on the substrate  90 . 
   (7) Next, the shutter means  72  and the valve  76  are closed. 
   (8) Next, the change-over valve  24  is opened to the chamber  70  alone and the pump system  22  is activated, evacuating the chamber  70  to substantially the same vacuum as that in which the chamber  10  is retained. 
   (9) Next, the change-over valve  24  is closed relative to the both chambers  10  and  70  and then the pump system  22  is stopped from operation. 
   (10) Next, the shutter means  71  is opened, the holder  81  carrying the substrate  90  is moved from the chamber  70  into the chamber  10  and disposed at a predetermined position in the upper part of the chamber  10 . At this time, the holder  81  is connected to the other end of the power source  15 . 
   (11) Next, the shutter means  71  is closed. 
   (12) Next, the heat source  41  in the heat source chamber  40  is turned ON, heating the substrate  90  up to a temperature of 350° C. 
   (13) Next, the light source  31  in the light source chamber  30  is turned ON. 
   (14) Next, the valve  19 A connected to the lower nozzle part  12   b  of the nozzle  11  in the reaction chamber  10  is opened, through which ammonia gas (NH 3 ) is introduced as a first reactive material gas from the gas source  18 A into the chamber  10 . At the same time, the valve  23  is opened and the valve  24  is opened relative to the chamber  10  alone and, further, the pump system  22  is activated, raising the pressure in the chamber  10  to 3 Torr. Then the valve  15 B connected to the upper nozzle parts  12   a  of the nozzle  11  is opened, through which disilane (Si 2 H 6 ) is introduced as a second reactive material ga from the gas source  14 B into the chamber  10  to provide therein a gas mixture of the ammonia gas and the disilane. The pressure in the chamber  10  is held at 3 Torr by regulating the valve  23 . In this instance, exhaust pipes  38  and  48  between the chambers  30  and  40  and the reaction chamber  10  are heated by heaters  39  and  49  mounted thereon, respectively. Even if the gas mixture flows back from the reaction chamber  10  in the pipes  38  and  48  toward the chambers  30  and  40 , it is vapor-decomposed by heat to deposit silicon nitride and silicon on the interior surfaces of the pipes  38  and  48 , preventing the silicon nitride and silicon from deposition on the inside surfaces of the chambers  30  and  40 . Furthermore, in order to prevent such a reverse flowing of the gas mixture, the valve  36  is opened, through which nitrogen or argon gas is introduced from the gas source  35  into the chambers  30  and  40 . 
   In such a condition, the gas mixture is excited by light from the light source  31  desposed in the light source chamber  31 , by which it is excited and vapor-decomposed, depositing a first silicon nitride layer as a first insulating layer on the substrate  90  at a rate of 17 A/min. 
   (15) Next, when the first silicon nitride layer is deposited to a thickness of about 500 A on the substrate  90 , the valve  23  is regulated and when the pressure in the chamber  10  is reduced to 1 Torr, the power source  15  is turned ON and then the light source  31  is turned OFF. 
   In such a condition, the gas mixture of the ammonia gas and the disilane is discharged or excited by electric power from the power source  15  into a plasma, in consequence of which a second silicon nitride layer is deposited as a second insulating layer on the first silicon nitride layer at a rate 2.1 A/sec. 
   (16) Next, when the second silicon nitride layer is deposited to a thickness of about 0.5 μm, the power source  15  is turned OFF and then the valves  15 B  19 A and  36  are closed but the valve  23  is fully opened, evacuating the chambers  10  and  30  to the same degree of vacuum as that under which the chamber  70  is held. 
   (17) Next, the valve  23  is closed and the pump system  22  is stopped and then the shutter means  71  is opened, through which the holder  81  carrying the substrate member  90  with the first and second insulating layers deposited thereon in this order is moved from the chamber  10  to the chamber  70 . 
   (18) Next, the shutter means  71  is closed and then the valve  76  is opened, through which the pressure in the chamber  70  is raised to the atmospheric pressure. 
   (19) Next, the shutter means  72  is opened, through which the holder  81  is taken out to the outside and then the substrate member  90  having formed thereon the first and second insulating layers is removed from the holder  81 . 
   In the manner described above, the insulating layer member as the layer member is formed on the substrate  90 . 
   (20) Next, the holder  81  with no substrate member  90  mounted thereon is placed in the chamber  70 , after which the shutter means  72  and the valve  76  are closed, the valve  24  is opened to the chamber  70  and the vacuum pump system  22  is put in operation, evacuating the chamber  70  to the same degree of vacuum as that under which the chamber  10  is retained. 
   (21) Next, the valve  24  is closed relative to the both chambers  70  and  10 , after which the shutter means  71  is opened, through which the holder  81  is placed in the chamber  10 , and then the shutter means  71  is closed. 
   (22) Next, the valve  19 B connected to the lower nozzle parts  12   b  of the nozzle  11  is opened, through which nitrogen fluoride (NF 3 ) is introduced as a first cleaning gas form the gas source  18 B into the chamber  10 . On the other hand, the valve  23  is opened and the valve  24  is opened to the chamber  10  and then the pump system  22  is put in operation, holding the pressure in the chamber  10  at 0.1 Torr. 
   (23) Next, the power source  15  is turned ON. 
   In such a condition, the first cleaning gas is discharged or excited into a plasma by electric power from the power source  15 , etching away unnecessary layers deposited on the inside surface of the chamber  10 , the inside surfaces of the windows  33  and  34 , the outside surface of the nozzle  11  and the outside surface of the holder  81 . The unnecessary layers are composed of the materials of abovesaid first and second insulating layer. 
   (24) Next, when the unnecessary layers are almost etched away, the power source  15  is turned OFF and the valve  19 B is closed, but the valve  19 C is opened, through which hydrogen as a second cleaning gas, supplied from the gas source  18 C, is introduced into the chamber  10 , maintaining the pressure therein at 0.1 Torr. 
   (25) Next, the power source  15  is turned ON again. The second cleaning gas is discharged or excited into a plasma by electric power from the power source  15 , cleaning the interior of the reaction chamber  10  including the windows  33  and  34 , the nozzles  11  and the holder  81 . 
   (26) Next, the power source  15  is turned OFF, after which the valve  19 C is closed and the valve  23  is fully opened, through which the chamber  10  is evacuated. When the chamber  10  is evacuated to the same degree of vacuum as that under which the chamber  70  is retained, the valve  23  is closed, stopping the pump system  22  from operation. 
   Thus a series of steps for forming an insulating layer member as a layer member on a substrate is completed. 
   Embodiment 2 
   Next, a description will be given of a second embodiment of the present invention for forming a semiconductor layer member as a layer member on a substrate. 
   This embodiment forms an amorphous silicon layer as the semiconductor layer member on the substrate  90  by the same steps as those in Embodiment 1 except the following steps. 
   (12′) In step (12) in Embodiment 1 the heating temperature of the substrate  90  is changed from 350 C to 250 C. 
   (14′) In step (14) of Embodiment 1 only the disilane (Si 2 H 6 ) gas is introduced into the chamber  10  and the pressure in the chamber  10  is changed from 3 Torr to 2.5 Torr. A first amorphous silicon layer is deposited as a first semiconductor layer on the substrate  90 . 
   (15′) In step (15) of Embodiment 1, when the first amorphous silicon layer, instead of the first silicon nitride layer, is deposited about 1000 A thick on the substrate member  90 , the disilane is discharged or excited into a plasma in place of the gas mixture of the ammonia and disilane, by which a second amorphous silicon layer is deposited as a second semiconductor layer on the first amorphous silicon layer. 
   (16′) In step (16) of Embodiment 1, when the second amorphous silicon layer, instead of the silicon nitride layer, is deposited about 1000 A, the power source  15  is turned OFF. 
   Embodiment 3 
   Next, a description will be given of a third embodiment of the present invention which forms an aluminum nitride (AlN) layer member as a insulating layer member on a substrate. 
   Embodiment 3 employs a same steps as those in Embodiment 1 except the following steps. 
   (14′) In step (14) of Embodiment 1 methyl aluminum (Al(CH 3 ) 3 ), instead of the disilane, is introduced from the gas source  14 A into the chamber  10 , whereby a first aluminum nitride (AlN) layer is deposited as a first insulating layer on the substrate  90 . In this case, the deposition rate of the first aluminum nitride layer is 230 A/min. 
   (15′) In step (15) of Embodiment 1 a second aluminum nitride layer, instead of the second silicon nitride layer, is deposited on the first aluminum nitride layer. 
   While in the foregoing the present invention has been described in connection with the cases of forming an insulating layer member having two insulating layers of the same material and a semiconductor layer member having two semiconductor layers of the same material, it is also possible to form an insulating layer member which has two insulating or protecting layers of different materials selected from a group consisting of, for example, Si 3 N 4 , SiO 2 , phosphate glass, borosilicate glass, and aluminum nitride. Also it is possible that an insulating or protecting layer of, for instance, the abovesaid insulating or protecting material and a conductive layer of such a metal as aluminum, iron, nickel or cobalt are formed in this order or in the reverse order to form a composite layer member. Furthermore, a semiconductor layer of a material selected from the group consisting of, for example, Si, Si  x C 1-x  (where 0&lt;x&lt;1), SiM x  (where 0&lt;x&lt;4 and M is such a metal as Mo, W, In, Cr, Sn or Ga) and the abovesaid insulating or protecting or conductive layer can also be formed in this order or in the reverse order to obtain a composite layer member. Moreover, although in the foregoing a low pressure mercury lamp is employed as the light source, an excimer laser (of a wavelength 100 to 400 nm), an argon laser and a nitrogen laser can also be used. 
   It will be apparent that many modifications and variations may be effected with out departing from the scope of the novel concepts of the present invention.