JPH0397219A - Manufacture and equipment of semiconductor device - Google Patents

Abstract

PURPOSE:To uniformize crystallizability by a method wherein the intensity of reflected laser light or transmitted laser light is measured, crystallizing process is ended when the above intensity becomes constant, and the condition for crystallization is optimized according to the change of transmitted light intensity. CONSTITUTION:In the case of heat annealing, an SiO2 film in the amorphous state is deposited on a glass substrate by, e.g. normal pressure CVD method. In order to crystallize an Si film deposited on the SiO2 film, the substrate is introduced into an annealing furnace. By adjusting mirrors 23, 24 for incident light and reflected light, laser light is reflected on a specimen 21, and received by a sensor 25. When the detected light intensity becomes lower than or equal to 30% of the incident light intensity, annealing process is ended. In the case of laser annealing, the reflected laser light is made to vertically enter the substrate, the transmitted light is received by a sensor 47, and the intensity is measured by a detector 48. Said light intensity is inputted to a host computer 49, and the laser light intensity is changed with a laser light output adjusting apparatus 50, thereby obtaining uniform crystallizability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for manufacturing a semiconductor device, and particularly to a method of crystallization annealing when manufacturing a thin film transistor using a polycrystalline silicon film.

[Conventional technology]

For example, low pressure chemical vapor deposition (LPGVD) is applied to an amorphous film such as a silicon oxide film (SiOz film) or a glass substrate. The process of depositing a silicon (Si) film by , plasma CVD, sputtering, evaporation, etc. and then crystallizing it using heat, laser, infrared lamp, etc. to improve the crystallinity of the Si film is a process used in semiconductor device manufacturing. It is used a lot. Currently, the conditions for these crystallization processes are set by the processing temperature and processing time in the case of thermal annealing, the wavelength, irradiation intensity and pulse width in the case of laser annealing, and the irradiation intensity and processing time in the case of lamp annealing. ing. The method for setting the conditions is to determine the conditions using the sample for investigation, and then perform the treatment under the same conditions. In addition, in the case of laser annealing, there is a method of changing the intensity of the laser beam using the reflected or transmitted light intensity of the laser beam used for processing, as shown in JP-A-58-112327, and JP-A-61-1999. 287
As shown in No. 234, a method has been adopted in which the location and intensity of laser processing are determined by measuring the intensity of reflected light at the portion to be processed by laser light.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, when the state of the Si film after deposition differs depending on the method and conditions for depositing the Si film, it is necessary to examine the annealing conditions each time. Further, even when deposited under the same conditions, the crystallinity after the same crystallization process may vary due to errors in the substrate temperature during deposition, etc. Furthermore, even though the crystallinity does not improve any further under the same conditions, long-term annealing treatment may increase strain, for example, when the substrate is made of glass. Even in the case of laser annealing, it was not possible to determine the processing conditions in advance because the reflected or transmitted light from the area being crystallized was measured. Furthermore,
In the manufactured semiconductor device, since other films are deposited on top of the semiconductor film, it is not possible to inspect the crystallinity after all the steps are completed in that state.

An object of the present invention is to make the crystallinity within and between substrates uniform by providing a square and a device that terminates the crystallization process when a certain level of crystallinity is obtained depending on the sample. .

[Means to solve the problem]

In the case of thermal and lamp annealing, the above object is achieved by continuously measuring the reflected or transmitted light intensity of the sample undergoing the crystallization process. Additionally, in the case of a process that instantly changes crystallinity, such as laser annealing, it is possible to measure the reflected or transmitted light intensity before the process and set the irradiation light intensity accordingly. .

Furthermore, by detecting the intensity of reflected or transmitted light from the semiconductor thin film after crystallization processing, it is possible to inspect the uniform state of crystallinity within the substrate and between substrates.

Furthermore, after the crystallization process, the semiconductor thin film is patterned,
By forming a pattern in which the intensity of reflected or transmitted light can be measured when forming the element, inspection can be performed even after the process is completed.

[Effect]

The intensity of light reflected and transmitted by a Si film with respect to laser light varies greatly depending on the crystallinity of the film or the deposition conditions. For example, in the case of thermal annealing, the crystallization rate changes depending on the crystallinity and thickness of the semiconductor thin film during deposition. Also. In the case of anil at a low temperature of about 600° C., no improvement in crystallinity occurs in a film in which single-stage crystallization occurs. By continuously measuring the intensity of reflected or transmitted light under these conditions, and increasing the processing temperature or deciding whether to terminate the crystallization process depending on the changes, the optimal crystallization conditions can be determined depending on the semiconductor thin film deposited. Anneal with

In addition, in the case of laser and lamp annealing, the Si
Since the state of reflection and absorption of irradiated light changes depending on the state of the film, the crystallinity after crystallization is not constant under the same conditions. Figure 1 shows an example of LPCVD on a glass substrate.
This figure shows changes in crystallinity, reflectance of ultraviolet light at a wavelength of 308 nm, and intensity of transmitted light of a Si film deposited by changing the substrate temperature using the method.

In samples whose crystallinity is measured during deposition, the reflectance and transmitted light intensity vary greatly. Furthermore, even in an amorphous sample, the intensity of transmitted light changes depending on the deposition conditions. By measuring this amount of change, the intensity of the irradiated laser or light can be set so that the effective energy used for crystallization is constant.

Furthermore, crystallinity can be evaluated by determining these intensities as al'l.

〔Example〕

1. In the case of thermal annealing, an amorphous SiOz film is deposited on a glass substrate by, for example, atmospheric pressure CVD, and on the SiO2 film, for example, L is deposited.
An amorphous Si film is deposited by the PCVD method. In order to crystallize the deposited Si film, the substrate is introduced into an annealing furnace having a structure as shown in Figure P2.The wavelength of the laser beam 29 to be measured is, for example, 308 nm in the ultraviolet light region.
For example, a hole of about 5 m in diameter for turning the N2 gas is opened in the furnace 28 in the incident and reflected light paths, and the laser beam is reflected on the sample 21 by adjusting the mirrors 23 and 24 for the incident light and reflected light. The sensor 25 receives the light.

At this time, the detected light intensity is, for example, 30% of the incident light intensity.
When the following occurs, the detector 26 sends a signal to the furnace control unit to terminate the reannealing process. Further, if the reflectance becomes constant at 30% or more during heat treatment, the crystallinity is improved by increasing the furnace temperature. however,
If the substrate is glass, the temperature is raised in a region below the softening point of the glass. In addition to making a hole in the furnace 28 as a method for entering the laser beam, the furnace itself can be hermetically sealed by using an optical fiber. In addition, the material of the furnace is quartz,
By setting the laser beam in the ultraviolet region that passes through quartz, a part of the furnace is made smooth as shown in FIG. 3, and the laser beam is transmitted through the furnace 38 and the laser beam is measured as it is.

2. In the case of laser annealing, an amorphous SiOz film is deposited on a glass substrate by, for example, atmospheric pressure CVD, and on the SiOz film, for example, L is deposited.
An amorphous Si film is deposited by the PCVD method. In order to crystallize the deposited Si film, the substrate is set in an apparatus having the structure shown in FIG. 4. A laser beam 40 oscillated from a laser device 41 is first separated by a mirror 42 with a reflection of about 10% and irradiated onto a sample position before crystallization. The substrate is glass, and the laser beam used is
iC) If the laser beam is in the ultraviolet region (for example, excimer laser dual wavelength 308 nm using XeCQ as a gas source) that passes through the z film, the reflected laser beam is incident perpendicularly to the substrate, and the intensity of the transmitted light is measured by a sensor. At step 47, the receiver detector 48 measures it. This light intensity is input to the host computer 49,
Depending on the intensity, the intensity of the laser beam irradiated for crystallization is changed by the laser beam output adjuster 50, so that uniform crystallinity can be obtained within the substrate. The laser beam transmitted through the mirror 42 is irradiated onto the sample by the approximately 10% transmission mirror 43 with an energy of approximately 80% of the irradiation intensity, thereby crystallizing the Si film. Further, the laser beam that has passed through the approximately 10% transmission mirror 43 is reflected by the mirror 44 and is incident perpendicularly to the sample surface on which the crystallization process has been completed, and the intensity of the transmitted light is measured by the sensor 47.
The crystallinity is evaluated in detail by measuring with the receiver detector 48.

At this time, if the light intensity at each position is memorized in the host computer 49, an in-plane map of the crystalline state of the sample can be created, which allows areas that require reprocessing to be reannealed to make the crystallinity uniform. let In this method, the substrate is scanned to process the Si film on the entire surface of the sample. Depending on the scanning method, the role of the laser light reflected by the mirrors 42 and 44 (determining the intensity of the irradiated laser light or controlling the crystallinity after crystallization) (detailed price)).

If the substrate is made of Si, for example, which does not transmit ultraviolet light, or if the laser beam is in the visible range, such as a ruby laser (wavelength 697 nm) even though the substrate is glass, the angles of the mirrors 42 and 44 are adjusted as shown in FIG. The reflected light at each position is incident on the sensor 57 and measured by the detector 58. At this time, in order to eliminate the influence of reflection from the sample by the laser beam for crystallization, the detection direction of the sensor 57 is set in a direction in which the reflected light of the laser beam does not enter (the reflected light spreads out from the sample in a hemispherical shape and is perpendicular to its tangent line). (other than direction). Further, by providing a band pass filter 59 that transmits only the wavelength of the laser beam used immediately before the sensor 57, wavelengths other than the irradiated laser beam are cut off.

In this way, the same laser beam device 41 simultaneously performs the setting of the irradiation light intensity, the crystallization process, and the evaluation of the crystallinity after crystallization.

3. In the case of lamp annealing, an amorphous Si○2 film is deposited on a glass substrate by, for example, atmospheric pressure CVD, and on the SiO2 film, for example, L is deposited.
An amorphous Si film is deposited by the PCVD method. In order to crystallize the deposited S1 film, the substrate is set in an apparatus having the structure shown in FIG. At this time, the wavelength for the heating lamp and the wavelength for measurement are selected to have different wavelengths so that they do not affect each other. For example, if infrared rays are used in a heating lamp,
The laser light wavelength for measurement is an Ar laser in the visible region (wavelength:
514 nm). At this time, in order to prevent the lamp light from being reflected from the substrate and entering the detector, there is a bandpass filter 6 just before the sensor 66 that transmits only the wavelength of the laser beam 60.
5 will be provided. If the reflectance received by the sensor 66 is, for example, 5
If it becomes 0% or less, a signal can be sent to the lamp output controller 68 of the infrared lamp 69 to terminate the process. Furthermore, assuming that the wavelength of the laser beam for measurement is in the ultraviolet region, the intensity of the light transmitted through the sample 63 is set as it+1, and if that value exceeds a certain value, the same processing as when measuring the reflected light is performed. terminate. In the case of lamp annealing, as in thermal annealing, when the reflected or transmitted light intensity remains constant and does not reach the target, the lamp irradiation intensity is increased for processing.

4. Crystallinity Evaluation Method and Apparatus A sample that has been crystallized using each method is set on a stage, and the reflected or transmitted light intensity is measured, for example, at several points within the substrate, in a straight line, or while scanning continuously. As a result, a map of the crystal state within the substrate is created. Further, by measuring the light intensity between substrates, variations in crystallinity between substrates and between lots are evaluated. Furthermore, for example, 10 μmφ is applied to each chip within the substrate or to a part of the substrate.
A pattern for evaluating the degree of crystallinity is formed, and the crystallinity of the semiconductor film is evaluated by concentrating laser light and measuring the intensity of reflected or transmitted light even after the final process is completed.

〔Effect of the invention〕

According to the present invention, in the case of heat and lamp annealing, it is possible to evaluate the crystallinity during the crystallization process and perform the optimum crystallization process, so that the crystallinity after the crystallization process due to variations during the deposition of the semiconductor film can be avoided. There is no change in crystallinity between the substrates, and the crystallization process is terminated when optimum crystallinity is obtained, thereby eliminating variations in crystallinity between substrates.

Furthermore, in the case of laser annealing, the absorption state of the laser light is measured before processing, and the laser light intensity is set accordingly. Furthermore, uniform crystallinity can be obtained by evaluating the crystallinity after the crystallization treatment and reprocessing where the crystallization is insufficient.

[Brief explanation of drawings]

Figure 1 is a diagram plotting the crystallinity, reflectance of a laser beam with a wavelength of 308 nm, and transmitted light intensity of a Si film deposited on a glass substrate by the LPCVD method while changing the substrate temperature. FIG. 4 is a diagram showing an embodiment of the thermal annealing method using the invention. FIG. 4 is a diagram showing an embodiment of the laser annealing method when the substrate transmits the laser beam using the invention. FIG. FIG. 6 is a diagram showing an example of a laser annealing method in which no light is transmitted through the lamp, and FIG. 6 is a diagram showing an example of a lamp annealing method using the present invention. 21. ,45,55.63... trial r},22.41・
・Laser device, 23, 24, 44, 54.62... Mira 25, 47, 57.66... Sensor, 26.48,
58.64...Detector, 27...Furnace controller, 2
8.38...Furnace, 29,39,40,51.60...
・Laser beam, 42... Mirror, 43... Approximately 10% transmission mirror, 4.6, 56.64... Sample stage, 49.
...Host computer, 50...Laser light output adjuster, 59.65...Bant pass filter, 68 Fig. 1 Fig. 4

Claims (1)

[Claims] 1. In the process of crystallizing a semiconductor thin film formed on a substrate, simultaneously with the crystallization process, the reflected or transmitted light intensity of a laser beam in a specific wavelength range is measured, and based on that value, the semiconductor thin film is crystallized. Manufacture of a semiconductor device, characterized in that the crystallization process is terminated when the crystallinity of the thin film reaches a constant state, and the crystallization process conditions are optimized according to changes in the reflected or transmitted light intensity. Method. 2. By measuring the intensity of reflected or transmitted light in the crystallized semiconductor thin film in the same manner as described in claim 1,
A detailed evaluation method for semiconductor devices characterized by detailed evaluation of variations in crystallinity between substrates or between substrates. 3. The method for manufacturing a semiconductor device according to claim 1 or 2, characterized in that whether to measure reflected light or transmitted light is selected depending on whether the laser light passes through the substrate. A method for manufacturing a semiconductor device. 4. A semiconductor device characterized in that a pattern for measuring reflected or transmitted laser light is formed in the substrate, making it possible to inspect crystallinity even after the semiconductor device manufacturing process is completed.