JPH04209565A - Optical beam melted recrystallized semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a high performance device without deteriorating characteristics of an element of other region by emitting a laser beam having high power, melting and recrystallizing it. CONSTITUTION:An Si substrate 1 is isolated by an SiO2 film 2, and an integrated region 3 of an FET of a memory driver of an SRAM and a peripheral circuit 4 are formed. An interlayer insulating film 5, thin films of a polysilicon 6, an SiO2 7, an Si3N4 8 are superposed, and a WSi2 reflecting film 9 is deposited. The film 9 is removed by etching only on the region 3. An Ar laser light 10 is emitted, polysilicon of a part having no reflecting film is melted, recrystallized, a MOSFET for a load is formed on the crystallized Si, and electrically connected to complete an SRAM. Since the power of the beam incident to the polysilicon except the region 3 is reduced by reflecting, the temperature of the polysilicon film of the part is lowered than that of the polysilicon film on the region 3 to suppress so-called peeling.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention relates to a light beam melted recrystallized semiconductor device in which a light beam melted recrystallized semiconductor film is formed on a region where bulk transistors are integrated, and elements such as transistors are formed on this film. Regarding the manufacturing method. [0002] Conventionally, a three-dimensional semiconductor device in which a polycrystalline semiconductor thin film transistor is formed on a bulk transistor integration region via an interlayer insulating film has been used as a high capacity, low power consumption SR.
It has been proposed to be used in AM cells, etc. (IEICE Technical Report, SDM90-25, p. 7-13.1990,
(See SDM90-34, p. 75-80.1990)
However, it is desired to further increase the capacity and reduce power consumption of SRAM without reducing data retention ability. [0003] That is, by three-dimensionally forming a load MOS transistor in a CMOS SRAM with high data retention on an integrated region of a driver transistor formed in a single crystal with an insulating film interposed therebetween, memory cells can be It is essential to reduce the leakage current of the load MOS transistor in order to reduce the area and at the same time improve data retention. [0004] As expected to meet this request,
A three-dimensional semiconductor device can be considered in which a load MOS transistor is formed in a semiconductor layer formed by melting and recrystallizing a polycrystalline semiconductor film deposited on a bulk transistor integration region via an interlayer insulating film using a light beam. [0005] FIG. 2 is an explanatory diagram of the configuration of a light beam melted recrystallized semiconductor device. In this figure, 21 is an St single crystal substrate, 22 is a field oxide film, 23 is a bulk transistor integration region, 24 is a peripheral circuit region, 25 is an interlayer insulating film, 26 is a polycrystalline Si film, 27 is a Sin: film, and 28 is Si
3N+ film, 29 is a laser beam. [0006] This semiconductor device has an interlayer insulating film 25 on a Si single crystal substrate 21 consisting of a bulk transistor integration region 23 in which a MOSFET, which is a driver transistor of a 5RANi memory cell, is formed and a peripheral circuit region 24 in which a peripheral circuit is formed. A polycrystalline Si film 26 is formed through the
On top of that is a SiO2 film 27, S! 3 Form an N+ film 28, scan and irradiate the laser beam 29 from above, melt the polycrystalline Si film 26, recrystallize it to crystallize it, and apply a load to this crystallized Si film. Ncho O
It is manufactured by forming transistors 81 to 81 and electrically connecting them as appropriate. [0007] FIG. 3 is a diagram showing the relationship between the power of the laser beam used for melt recrystallization and the leakage current of pMO3 formed in the layer. In this figure, 1 curve A shows pch in the molten recrystallized semiconductor film formed on the SiO2 film with steps.
For reference, curve B shows the leakage current when a MO3FET is formed, and curve B shows the leakage current when a pMOSFET is formed on a molten recrystallized semiconductor film formed on a flat SiO2 film. The device used for the measurements in this figure has a channel length of 1.8 μm, a drain voltage of 13 V for measurement, and the vertical axis indicates the current value per μm of gate width. [0008] As shown in this figure, when a molten recrystallized semiconductor film is formed on a 5iOz film having steps as in the apparatus of the present invention, the molten recrystallized semiconductor film formed on a flat SiO2 film is Although the leakage current is larger than when the three-dimensional semiconductor is formed, the two match when the laser beam power is about 3.8W. The electrical properties of the device improve as the power of the light beam increases. [0009]

[Problems to be Solved by the Invention] In this conventional technique, polycrystalline silicon is
The lower layer of the film is the field oxide film of the bulk transistor (
Since the thickness is approximately 6,000 A), heat escapes to the lower layer in this part is poorer than that above the bulk transistor integration region, and the temperature tends to rise more easily. [00101 Therefore, for the purpose of improving the electrical characteristics of three-dimensional integrated circuits, the power of the laser beam is increased and polycrystalline Si on the bulk transistor integration region is
When the film is adjusted to the proper melting state, the polycrystalline Si film on the field oxide film will be at a higher temperature than that of the polycrystalline Si film.
As the laser beam scans, a phenomenon occurs in which the polycrystalline Si film in that region melts to an extreme extent and scatters to both sides of the scanning path (this phenomenon is called a peeling phenomenon). Once started, as the laser light beam scans, it spreads to the three-dimensional integrated circuit forming area, and the molten Si scattered on both sides of the scanning path solidifies into large lumps, causing a high temperature of about 5000 A. There were two people who solidified into enemies. [00111 When this phenomenon occurs, the surface of the molten recrystallized Si film becomes uneven, making it difficult to set the conditions for etching that is subsequently added for buttering, and creating a problem in which a three-dimensional semiconductor cannot be formed. . In order to prevent this phenomenon, it is conceivable to add a melt recrystallization step after removing the polycrystalline Si film other than on the bulk transistor integrated region by etching or the like. [0012] However, according to this method, only the interlayer insulating film exists on the bulk transistor (24 in FIG. 2) forming the peripheral circuit formed outside the bulk transistor integration area, so the laser beam is There is a possibility that the beam will directly irradiate this bulk transistor and deteriorate its characteristics. Therefore, it is necessary to leave the polycrystalline Si film on areas other than the bulk transistor integration area. An object of the present invention is to provide a high-performance fused-recrystallized semiconductor device by irradiating a high-power laser beam without causing the above-mentioned problems. [0013]

[Means for Solving the Problems] A light beam melted recrystallized semiconductor device according to the present invention includes a semiconductor substrate having a bulk transistor integration region, an interlayer insulating film formed on the semiconductor substrate, and an interlayer insulating film formed on the semiconductor substrate. A semiconductor film melted and recrystallized by irradiating a light beam from above a light beam reflecting film having an opening only in the bulk transistor integration region; A structure including elements such as transistors formed in a semiconductor film was adopted. [0014] Furthermore, the method for manufacturing a light beam melted recrystallized semiconductor device according to the present invention includes a step of forming an interlayer insulating film on a semiconductor substrate having a bulk transistor integration region, and a step of forming a multilayer insulating film on the interlayer insulating film. A process of forming a crystalline semiconductor film, a process of forming a light beam reflection film on the polycrystalline semiconductor film in a portion other than the bulk transistor integration area, and a process of irradiating a light beam from above the light beam reflection film to A process of melting and recrystallizing a polycrystalline semiconductor film and a process of forming elements such as transistors in the melted and recrystallized semiconductor film were adopted. [0015]

[Operation] When a polycrystalline Si film is melted and recrystallized using the means of the present invention, the power of the laser beam incident on the polycrystalline Si film other than on the bulk transistor integration area is reflected and reduced. The temperature of the polycrystalline semiconductor film in this portion is lower than that of the polycrystalline Si film on the bulk transistor integration region, and the above-mentioned so-called peeling phenomenon can be suppressed. [0016]

EXAMPLES The present invention will be explained in detail below. Figure 1 shows
1 is a schematic configuration diagram of a light beam melted recrystallized semiconductor device according to an embodiment of the present invention. In this figure, 1 is a Si single crystal substrate, 2 is a field oxide film, 3 is a bulk transistor integration area, 4 is a peripheral circuit area, 5 is an interlayer insulating film, 6 is a polycrystalline Si film, 7 is a 5in2 film, and 8 is a Si3N+ film, 9 is WS
i2 reflective film, 10 is a laser beam. [0017] In this semiconductor device, a field oxide film 2 for isolating each element is formed on an S1 single crystal substrate 1 using a conventionally known manufacturing process, and the semiconductor device is surrounded by the field oxide film 2. In this figure, a bulk transistor integration region 3, which is a driver transistor of an SRAM memory cell, and a peripheral circuit region 4, which are composed of three ~■○5FETs in this figure, are formed.
: Film/BPSG film/5i02 film (100nm/300n
A polycrystalline Si film 6 is deposited on top of the interlayer insulating film 5, and a 50 nm thick SiO2 film 7 and a 1100 nm thick S! 3 N4 membrane 8
A WSiz reflective film 9 having a thickness of 1100 nm is further deposited thereon, and only the portion of the WSiz reflective film 9 on the bulk transistor integration region 3 is removed by etching. [0018] In this state, a laser beam 10 from an Ar laser is irradiated to melt and recrystallize the polycrystalline Si film 6 in the area where there is no WSiz reflective film, and this crystallized Si film is By forming a MOS transistor for load and electrically connecting it as appropriate, SRAM
Manufacture. The conditions at this time are shown below. 1. Laser power 4W 28 Laser wavelength 488 nm3, Laser device speed 150mm/5ec4, Substrate temperature 500°C [0019] This substrate temperature is because the upper surface of the substrate is heated to about 1415°C by irradiation with laser light. The temperature is raised to alleviate the strain that occurs in the substrate. In addition, a cap layer, Si
Oz /S i:+N4 film (7,8) is composed of molten S
It has the function of maintaining the T shape and suppressing peeling, and the function of improving laser light absorption efficiency and efficiently melting and recrystallizing. [00201 In the above embodiment, a laser beam was used as the light beam and Si was used as the semiconductor material, but it goes without saying that the present invention is not limited to these light sources and materials. Further, the present invention is not limited to SRAM, and can be widely applied to a process of melting and recrystallizing using a light beam. [Effects of the Invention] According to the present invention, polycrystalline St on a bulk transistor integrated region can be melted and recrystallized with high power without peeling off polycrystalline Si.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a light beam melted recrystallized semiconductor device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the configuration of a light beam melted recrystallized semiconductor device.

FIG. 3 is a diagram showing the relationship between the power of the laser beam used for melt recrystallization and the leakage current of 9MO8 formed in the layer.

[Explanation of symbols]

I Si single crystal substrate 2 Field oxide film 3 Bulk transistor integration area 4 Peripheral circuit area 5 Interlayer insulation film 6 Polycrystalline Si film 7SiO2 film 8Si3N2 film 9WSi2 reflective film 10 Laser light beam

Claims (2)

[Claims] 1. A semiconductor substrate having a bulk transistor integration region, an interlayer insulating film formed thereon, and a polycrystalline semiconductor film formed on the interlayer insulating film, with an opening formed only in the bulk transistor integration region. A semiconductor film melted and recrystallized by irradiating a light beam from above a light beam reflecting film having a structure, and an element such as a transistor formed in the melted and recrystallized semiconductor film. A light beam melting recrystallization semiconductor device. 2. A step of forming an interlayer insulating film on a semiconductor substrate having a bulk transistor integration region, a step of forming a polycrystalline semiconductor film on the interlayer insulating film, and a step of forming a polycrystalline semiconductor film on the polycrystalline semiconductor film. A process of forming a light beam reflection film in a portion other than the bulk transistor integration area, a process of irradiating a light beam from above the light beam reflection film to melt and recrystallize the polycrystalline semiconductor film, and a process of recrystallizing the polycrystalline semiconductor film. 1. A method for manufacturing a light beam melted recrystallized semiconductor device, comprising the step of forming elements such as transistors in a semiconductor film.