Exposure by electron beam

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to the useless method of preventing the fall of charge 9 and the pattern accuracy by the change of the height of a sample especially to an electron optics system to an electron beam exposure method. [Description of the Prior Art] Since the scanning length on a sample when carrying out the predetermined angle deviation of the five electron beams will change and a focus will shift if the height of a sample changes to an electron optics system, the accuracy of the pattern drawn on a sample falls. For this reason, conventionally, aside from the electron optics system for exposure, the optical system which detects the height of a sample using light is established, and there are some which feed back that detection value to an electron optics system, and compensated height change of the sample. However, a method of detecting height using this light, The necessity of providing insulators, such as glass indispensable to the optical system of light, near the electron optics system is charged with dust, this is charged with an electron beam, and since it becomes a cause which produces the position drift or astigmatism of an electron beam and the optical system of light other than an electron optics system is needed, there is a fault to which a device becomes intricately and expensive. detecting the interval of two fixed points still provided on the sample by the electron optics system for exposure without using the optical system of light from the deviation angle of an electron beam -- the height of a sample -- To -- although there are some which were made like, highly precise height measurement is difficult for this, and it has a Really fault. [Objects of the Invention] The present invention measures the height of a sample with high precision using the electron optics system for exposure, without using the optical system of light, and an object of the present invention is for this to press down smaller the fall of the pattern accuracy by height change of a sample, and it is Really. [Elements of the Invention] The useless present invention which achieves this object changes object lens current of an electron optics system for exposure, and scans unevenness on a sample two or more times with an electron beam, Height of a sample is measured from distribution of contrast of a reflective electronic signal waveform then obtained, and it is in an electron beam exposure method which carries out the feed bank of the measurement result to drawing conditions, such as deflecting voltage adjustment, and drew it. [Example] Drawings 1 thru/or 4 explain the example of the present invention below. As shown in Drawing 1, Ridge-like projection (a concave may be sufficient) 2 is provided in the surface of sample 1, and a reflective electronic signal waveform as shows the reflective electron detector which is made to correspond to this projection 2 and is not illustrated by A and B is obtained. Although the difference of each maximum and minimum of these reflective electronic signal waveforms A and H is called contrast Ca and Cb, the value of this contrast shows Ql Larger value by which focal Agreement of the electron beam 3 which passes projection 2 is carried out more correctly. Then, the object lens current of an electron optics system for exposure which is not illustrated is changed, and when it is made to change, it scans each time so that projection 2 may be crossed, and the relation between the value of the contrast at that time and the above-mentioned object lens current is shown, it is every only about the focal length of electron beam 3, The distribution curve of contrast as shown in Drawing 3 with numerals C1 receives one. When the focus of electron beam 3 suits from distribution curve C1 of this contrast most surely to projection 2, object lens current 401 in case contrast shows the maximum is obtained. It is good to decide Threshold"-Level level as shows object lens current 401 in case this contrast shows the maximum in Drawing 3 with numerals S at To, and to obtain object lens current A.I. Artificial Intelligence in the intersection of this and distribution curve C1 of contrast, and 42 from Because and a lower type. 1 Akira Object lens current po1 in case it moves to the right direction in Drawing 3 as sample 1 * takes for approaching an object lens and numerals C2 show to the 3rd dancing, and contrast becomes the maximum as mentioned above (oz corresponds to the height of sample 1.) Then, as shown in Drawing 4, the height of sample 1 at that time can be measured for the relation between object lens current in case Ahead contrast becomes the maximum using a known sample, and the height of the sample at that time from If you do, the above-mentioned object lens current 4o1, or lo2. Since the change rate of the object lens current to change of the height can take greatly enough to the control unit of the current, height measurement of this sample 1 can be performed with high precision. The feed bank of this measurement result is carried out to drawing conditions, such as deflecting voltage adjustment and object lens current, and a gap of the height of sample l is compensated and drawn. [Effect of the Invention] * Without using the optical system of light according to the present invention, as stated above, the height of a sample can be measured with high precision using the electron optics system for exposure, and it does not equip intricately and at an expensive price by the ability to press down smaller the fall of the pattern accuracy by height change of a sample for this reason.

[Brief Description of the Drawings]

Drawing 1 is a partial fracture enlarged drawing showing the relation of a concavo-convex example and the electron beam which are formed in the surface of the sample for carrying out the present invention, The figure showing a reflective electronic signal waveform when Drawing 2 scans a projection with an electron beam, the figure showing distribution of the contrast of a reflective electronic signal waveform accompanying change of object lens current in Drawing 3, and Drawing 4 are figures showing object lens current in case contrast is the maximum, and the relation of sample height. 1 ... A sample, 2 ... A projection, 3 and an electron beam, A, B ... Reflective electronic signal waveform. Ca, Cb ... Contrast, C1, C2 ... The distribution curve of contrast, S and a Threat N Yold level. Applicant Toshiba machine machine incorporated company